TECHNICAL FIELD
The present invention relates to an elongated fluid actuator arrangement according to the
preamble of claim 1.
The present invention concerns the industry using hydraulic and/or pneumatic actuators for
different types of applications and also concerns the manufacture industry producing such
arrangements.
The invention is not limited thereto, but can also be used for replacing electrical actuator
arrangements and can be adapted for application of a wide range of different types
industries.
BACKGROUND ART
There is a desire to provide an elongated fluid actuator arrangement that reliably could
distribute proper control functionality regarding force and motion rate of the piston rod
member.
Current technology as published uses elongated fluid actuator arrangements that are
designed with specific features for achieving desired pressure performance and pressure
distribution for different motion rates and actuating forces. This may imply overweight and
over-dimension materials.
Current technology also often uses a centrally controlled operation for controlling maximum
motion rate and force of the piston rod member by means of regulating the fluid flow and
pressure of the fluid supply device. Such centrally controlled feeding of fluid may make such
arrangement ineffective.
US 4 506 867 discloses a jacking apparatus for effecting motion of loads by means of two
double-acting hydraulic cylinders for providing increased force of a power stroke. Hydraulic
fluid pressure is controlled to a predetermined flow rate to the hydraulic cylinders for
increasing the speed of a repositioning stroke of the apparatus.
US 3220317 discloses a servo system having a hydraulic motor system with two pistons
arranged in tandem for each motor. The system uses two motors connected in parallel so
that their motions are in fixed proportions and their forces are added. The system may also
be arranged with the motors in series so that forces are in fixed proportions and that motion
is added.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an elongated fluid actuator arrangement that
performs a robust and reliable functionality even if there is variation in axial force acting upon
the piston rod member and/or variation in time for engagement and disengagement of the
fluid controlled membrane member.
An object of the present invention is to develop an energy saving elongated fluid actuator
arrangement providing reliable functionality and/or providing actuator arrangements that can
be applied to long distance and extended piston rod members. These are preferably put into
use in e.g. lifts and high bay storage arrangements having extended and relatively long
piston rods.
A further object is to increase energy efficiency of an elongated fluid actuator arrangement
operating under various motion/movement and force performance selected from actual
requirement or condition, without need of additional energy consuming throttling valves.
A yet further object is to provide an elongated fluid actuator arrangement exhibiting a lower
weight compared with prior art fluid actuator arrangements.
An object is to improve current fluid actuator arrangements in mobile and industrial
applications.
An object is to provide elongated fluid actuator arrangements to accomplish work with only
minor amount of input force.
A yet further object is to minimize the environmental impact by lowering noise and reducing
leaks.
One aspect is to provide an elongated fluid actuator arrangement that can be used in
material handling equipment, agricultural equipment, vehicles, excavators, wellhead and
jacking systems, construction equipment, hydraulic presses and others. A further aspect is to
adapt the arrangement to 3 D-printing in plastic, composite and/or metal applications for
aircraft or automotive industry. A yet further aspect is to provide an arrangement that can be
used in automated storage and retrieval systems for car parking and rough-terrain robots, so
called legged robot systems. There is also an object to provide an elongated fluid actuator
arrangement that can be used in military equipment utilizing hydraulic and/or pneumatic
mechanisms. This includes armoured personnel carriers, aircraft material handlers, cranes
and loaders, hook lifts, track adjusters and truck-mounted bridge layers etc.
At least one of said objects has been achieved by an elongated fluid actuator arrangement
comprising: a first and second cylinder housing extending in a longitudinal direction,
respective cylinder housing encompasses a first respective a second piston body; the
respective piston body divides the respective cylinder housing in a first and second cylinder
chamber; the arrangement being adapted for connection to a valve member means of a fluid
supply device; a piston rod member extending through said respective first and second
piston bodies; the first piston body comprises a piston rod engagement and disengagement
means, which is adapted to engage or disengage the first piston body to/from the piston rod
member, wherein an engagement area, defined by an engagement zone between the first
piston body and the piston rod member, is larger than a cross-sectional piston area of the
first piston body.
Preferably, a sensor device is arranged to the elongated fluid actuator arrangement for
determining an actual cylinder-piston feature value, a control unit is associated with the
sensor device and with the valve member means for controlling said engaging and
disengaging of the piston body to/from the piston rod member.
Thereby is achieved that a monitoring and control of the first piston body motion in the first
cylinder housing.
Thereby is achieved that monitoring and control of the second piston body motion in the
second cylinder housing.
The engagement zone is defined as an engagement area corresponding with the contact and
clamping area of the first piston body (or second piston body). I.e. the area of the piston body
which is in engagement with the piston rod when the piston body is engaged. The measure
of the engagement area e.g. has an extension corresponding with the radially inward
projected extension of a cavity of the piston rod engagement and disengagement means.
The cavity is co-axially arranged in the piston body and exhibits the same central axis as the
cylinder housing and the piston rod member in the longitudinal direction. The cavity may be
arranged for fluid communication with the respective first and second cylinder chamber.
Suitably, the piston rod engagement and disengagement means thus provides in
engagement (clamping/gripping) sequence a secure hold of the piston rod by means of the
control unit commanding the valve member to fed fluid with a first fluid pressure according to
a pre-determined data scheme.
Preferably, the piston rod engagement and disengagement means thus provides in d is
engagement (release) sequence a release of the piston rod from the piston body by means
of the control unit commanding the valve member to fed fluid with a second fluid pressure
according to a pre-determined data scheme, wherein the second fluid pressure is low
enough for said release, but high enough for making a retraction stroke.
Preferably, the cavity is arranged for fluid communication with a fluid supply via an exterior
fluid port arranged on a first envelope surface of a first sleeve portion of the first piston body.
The exterior fluid port is arranged on a segment of the first sleeve portion protruding from the
first cylinder housing in the longitudinal direction.
Suitably, the cavity is arranged for fluid communication with a fluid supply via an exterior
central fluid port arranged on the first cylinder housing. The piston rod engagement and
disengagement means is adapted to be activated by said fluid supply device via the exterior
central fluid port arranged on the first cylinder housing coupled to a longitudinal groove
provided in an interface between the piston body and the cylinder housing interior, which
longitudinal groove is in fluid communication with the piston rod engagement and
disengagement means.
In such way is achieved that separate fluid transfer can be provided for a clamping action.
Preferably, the first piston body comprises a first sleeve portion and the first protruding
portion.
Suitably, the first protruding portion protrudes from a first envelope surface of the first sleeve
portion in a direction radially outward.
Thereby is achieved a piston body with a piston force area having an extension
perpendicular to the longitudinal axis.
Preferably, the (respective first, second and/or third etc.) piston body comprises an elongated
sleeve-shaped engagement and disengagement section (means) extending in the
longitudinal direction, the engagement and disengagement section is arranged to engage
and/or disengage with the piston rod member by means of a cavity that can be pressurized.
Suitably, the cavity is arranged within the elongated sleeve-shaped engagement and
disengagement section which is oriented co-axially with the section.
Preferably, the cavity extends more than half the length of the elongated sleeve-shaped
engagement and disengagement section in the longitudinal direction.
Suitably, the cavity extends less than 99% of the length of the elongated sleeve-shaped
engagement and disengagement section in the longitudinal direction.
In such way is provided a reliable engagement of the elongated sleeve-shaped engagement
and disengagement section to the piston rod member.
Preferably, the extension of the cavity in the longitudinal direction is 70-90% of the length of
the sleeve-shaped engagement and disengagement section.
Suitably, the sleeve-shaped engagement and disengagement section exhibits outer envelope
surfaces which are slidingly arranged through end cap bores of a cylinder housing.
Preferably, a protruding portion which protrudes from the outer envelope surfaces and in a
direction radially outward towards and in contact with an inner sliding surface of the cylinder
housing.
Suitably, the protruding portion exhibits opposite piston force areas.
Preferably, the opposite piston force areas exhibit an extension that is transverse to the
longitudinal direction.
Thereby is provided that the first piston body, when pressurizing the first cylinder chamber
with a first pressure, will be engaged and clamped (locked) to the piston rod member by
means of the piston rod engagement and disengagement means being actuated by said first
pressure. Disengagement of the first piston device from the piston rod member will be
provided when the first cylinder chamber is pressurized with a second pressure or not being
pressurized.
Thereby is achieved an arrangement that is robust and that will function in a reliable way.
Suitably, the first piston body comprises a first protruding portion protruding in a direction
radially outward with a first cross-sectional (transverse to the longitudinal direction) measure
and defining opposite cross-sectional piston areas. The piston body exhibits a first length in
said longitudinal direction. A first sleeve portion exhibits a smaller second measure in crosssection
than the first measure. The first sleeve portion defines an additional measure to the
first length defining a second length in said longitudinal direction. The first sleeve portion
comprises a piston rod engagement and disengagement means adapted to be operated by a
fluid supply device.
According to one aspect of the invention, the arrangement is preferably made as compact as
possible, wherein the piston body exhibits the above-mentioned first length. An engagement
area of a through bore (extending in said longitudinal direction and centrally of the piston
body) of a piston body requires some kind of strengthening of the engagement between the
piston body and the piston rod member. By forming the piston body with a sleeve portion
extending in the longitudinal direction from the protruding portion, the engagement area will
be sufficient large for rigid engagement to the piston rod.
Preferably, the protruding portion comprises an outer sliding surface arranged for sliding in
the cylinder housing for sliding contact with the cylinder housing wall. The protruding portion
is also arranged with the opposite piston areas, which areas extend in transverse direction to
the longitudinal direction.
Suitably, the length of the sleeve portion determines the extension of the engagement area
of the piston engagement and disengagement means (such as a membrane member)
arranged within the sleeve portion and/or piston body. The membrane member is provided
for engagement and disengagement (e.g. by engaging an inner surface of the sleeve portion)
of the piston body to the piston rod member. This can be made by pressurizing the piston rod
engagement and disengagement means (e.g. the membrane member).
Preferably, the engagement area A2 is larger than the cross-sectional (effective) piston area
A 1. By experiments made by the applicant there has been shown that by such relation, the
engagement is optimal between the piston rod and the piston body.
Thus, according to one aspect
A2 > Al
According to another aspect
A2 > 2* A1
According to yet a further aspect
A2 > 10 * Al up to 12 to 15 * Al
According to one aspect
A2 > 15 to 25 * Al or larger
Thereby is achieved a clamping of the piston body to the piston rod member by means of a
fluid pressure in a membrane cavity of the membrane member that is the same pressure that
acts upon the cross-sectional piston area, without any need of additional pressure
strengthening device applied to the membrane member.
Suitably, the piston rod engagement and disengagement means is adapted to be operated
by said fluid supply device via said cylinder chambers.
Alternatively, the operation of the piston rod engagement and disengagement means is
provided by pressurization of the respective cylinder chamber by means of the control unit
controlling the valve member means.
Preferably, the piston rod engagement and disengagement means comprises a cavity in the
first sleeve portion forming a membrane member, which cavity is arranged for fluid
communication with respective cylinder chamber.
Suitably, the membrane member is formed by an inner sleeve surrounded by an outer
housing coaxially arranged around the inner sleeve with a distance forming the cavity.
Preferably , the cavity (or at least two cavities) thus being formed between an outer surface
of the inner sleeve and an inner surface of the surrounding outer housing. The inner sleeve is
made flexible and comprises e.g. bronze-based material or other suitable flexible materials.
The bronze-based material also exhibits low frictional coefficient.
Suitably, the inner sleeve comprises a material that provides both flexibility (for optimal
clamping properties) and low frictional coefficient.
Preferably, the open ends of the outer housing is covered by a respective support ring for
fixation of the inner sleeve within the outer housing. Seals or O-rings are arranged in end
positions of the membrane between the outer surface of the inner sleeve and the inner
surface of the outer housing for providing a seal between the inner sleeve and the outer
housing.
Alternatively, a main fluid passage is arranged for fluid communication with the piston rod
engagement and disengagement means and joins a branch junction diverging into a first and
second passage to the respective cylinder chamber.
Suitably, at least the first fluid passage enters at the cross-sectional piston area of the first
cylinder chamber.
Alternatively, at least the second fluid passage enters at the cross-sectional piston area of
the second cylinder chamber.
Preferably, the protruding body portion and the sleeve portion are made in one piece.
Thereby is achieved reliable operation and cost-effective production of the arrangement.
Suitably, the second piston body comprises a second piston rod engagement and
disengagement means.
Preferably, the second piston body comprises a second protruding body portion having a
third measure and a second sleeve portion having a smaller fourth cross-sectional
(transverse to the longitudinal direction) measure than the third measure.
Suitably, the first measure corresponds with the third measure.
Preferably, the second length is larger than the cylinder housing length in said longitudinal
direction.
In such way a relatively low pressure can be used for operation of the elongated fluid
actuator arrangement by means of providing a relatively large engagement area (in relation
to the cross-sectional piston area) of the membrane member.
Suitably, a third cylinder housing encompassing a third piston body is arranged to said piston
rod member, the third piston body comprises a third piston rod engagement and
disengagement means.
Preferably, a first cross-sectional piston area of the first piston body differs in measure from a
second cross-sectional piston area of the second piston body.
There is thus possible to control the elongated fluid actuator arrangement performance by
altering the arrangement's effective force area (cross-sectional piston area) during operation.
This introduces a new level of energy efficiency to hydraulic and/or pneumatic systems used
in power transmissions.
Suitably, the arrangement comprises a first actuator provided with a first cross-sectional
piston area, a second actuator provided with a second cross-sectional piston area
corresponding with the first cross-sectional piston area, a third actuator provided with a third
cross-sectional piston area, a fourth actuator provided with a fourth cross-sectional piston
area, the third cross-sectional piston area is twice as large as the first cross-sectional piston
area, the fourth cross-sectional piston area is twice as large as the third cross-sectional
piston area.
Preferably, the valve member means of the fluid supply device is associated with a control
unit.
Suitably, the membrane member comprises a plurality of cavities.
Preferably, the membrane member comprises a cavity gap or slot, which extends over nearly
the total second length of the sleeve portion and/or circumferentially (co-axially) adjacent the
inner surface of the sleeve portion. The cavity is connected to a passage arrangement, which
has an entrance opening (fluid port) or several openings arranged in communication with the
cylinder housing interior (first cylinder chamber and second cylinder chamber).
Suitably, the cavity gap or slot (or a plurality of gaps) co-axially follows the circumferential
perimeter of the sleeve portion, seen in cross-sectional view, at a pre-determined distance
from the inner surface (engagement surface) of the sleeve portion.
Preferably, the cavity gap is connected to a fluid passage, which has a fluid port or several
openings being in communication with the interior of the cylinder housing (i.e. with both or
one of the first and second cylinder chamber).
In such way is achieved that the pressure in the pressurized cylinder chamber is the same as
the pressure of the pressurized membrane member.
Suitably, the protruding portion divides the cylinder housing in said first and second cylinder
chamber.
By pressurizing the first chamber, the pressurized fluid will entry the fluid port (e.g. arranged
at the pressure area of the piston body facing the first cylinder chamber or at other surface
portion of the piston body facing the first cylinder chamber) and pressurizing the cavity of the
piston rod engagement and disengagement means (membrane member). The pressurizing
of the membrane member will provide an expansion of the inner surface of the sleeve portion
in a direction radially inward. The piston body will thereby be clamped to the piston rod
member by the engagement of the inner surface to the piston rod member.
Suitably, the sleeve portion exhibits a material thickness defined between the cavity and an
outer perimeter surface of the sleeve portion that is larger than the thickness defined
between the cavity and the inner surface of the sleeve portion. This implies that no
expansion of the outer surface is made during said pressurization of the membrane member.
This embodiment is suitable when the sleeve portion extends from both exterior ends of the
cylinder housing. This provides tight sealing between cylinder housing and the piston body
during operation. The inner surface of the sleeve portion is in engagement with the piston rod
member in the engagement state by means of the pressurized cavity gap of the membrane
member pressing the inner surface towards the piston rod member.
The membrane member cavity is preferably positioned one sixth to one third of the thickness
of sleeve portion material seen in radial direction and in direction from the inner surface.
Suitably, the thickness of material is selected from the expected engagement force thereby
providing strength to the piston body and preventing that said outer surface expansion
occurs and also selected from maximal axial force acting upon the piston body.
Suitably, the sleeve portion is partly exposed outside the cylinder housing.
This implies that efficient detection (by human eye or other by other suitable way to
determine the position of the exposed sleeve portion outside the cylinder housing) of the
position of the piston body relative the cylinder housing will be possible.
By alternate controlling the motion (and engagement/disengagement) of the respective first
and second piston body, the piston rod can be propelled a considerable distance (extremely
long stroke performance) and alternatively with different forces. The alternate controlling of
the motion is performed by proper actuating of the valve member means.
Preferably, the area of the membrane member is 5 to 30, preferably 10 to 20, times larger
than the cross-sectional (effective) piston area.
By using a relatively large engagement and disengagement means (membrane member)
area in relation to the piston area, the engagement of the piston body to the piston rod
member is rigid. The axial pressure/force acting on the piston body (piston area), by means
of the pressurized fluid in the cylinder chamber, provides a certain load to the piston body.
The clamping force (engagement of the piston body to the piston rod member) or engaging
force provides clamping (engagement) of the piston body to the piston rod member. The
engaging force provides sufficient friction fixing the piston body in position to the piston rod,
wherein the engagement force prevails over the axial force.
Such relatively large engagement area of the piston rod engagement and disengagement
means implies that low fluid pressure can be used.
Preferably, the arrangement is used for hydraulic application and the hydraulic pressure used
is between 100 to 300 bar, preferably 200 to 250 bar depending on application.
In such way fatigue failure (fracture) or other damage of the membrane can be avoided.
Suitably, the hydraulic pressure is up to 450 bar.
Hence, service cost and manufacture cost could be reduced as conventional material can be
used to a greater extent.
Thereby is achieved quick engagement and disengagement of the piston body to the piston
rod.
This is made by direct fluid communication between the pressurized cylinder chamber and
the membrane member cavity.
Preferably, the piston body comprises a first passage arrangement adapted for fluid
communication with said cavity gap.
Suitably, a shuttle valve is arranged in said first piston device and is adapted for direct fluid
communication with said first cavity and said first and second cylinder chamber of the first
cylinder. The basic structure of a shuttle valve is like a cavity having e.g. three openings, one
on each end and one in the middle. A ball or other blocking valve element moves freely
within the cavity. When pressure from a fluid is exerted through one end opening it pushes
the ball towards the opposite end. This prevents the fluid from traveling through that opposite
end opening, but allows it to flow through the middle opening. In this way two different
sources can provide fluid pressure to a common membrane member without any back flow
from cylinder chamber to the other.
In such way is achieved that the cylinder chamber having the highest pressure (and thereby
propelling the piston body) will provide the membrane member cavity with the same pressure
as in the pressurized cylinder chamber. The membrane member will thus be pressurized
(expanding the inner surface of the piston body) and provides engagement of the piston body
to the piston rod, wherein the piston body manage propel the piston rod.
Preferably, the shuttle valve is arranged in a passage line arrangement of the protruding
portion.
By means of the passage arrangement providing a direct fluid communication between the
pressurized cylinder chamber and the membrane member a reliable operation of the
elongated fluid actuator arrangement is achieved.
Thereby the risk for fluid leakage, jamming, operational stop etc. is more or less eliminated.
Alternatively, the passage arrangement comprises a main passage in one direction joining
the membrane member cavity and in the other direction joins e.g. a T-junction (including the
shuttle valve) diverging into a first and second fluid line each connected to the respective
cylinder chamber.
Suitably, the first fluid line of the protruding portion comprises an inflow port on the first
cross-sectional piston area and the second fluid line of the protruding portion comprises an
inflow port on the second cross-sectional piston area.
Preferably, a returning arrangement is provided for returning at least one piston body to a
starting point relatively its cylinder housing, in which starting point the piston body is engaged
to the piston rod for propelling the piston rod.
Preferably, the returning is provided by the fluid supply and valve member means controlled
by the control unit.
Suitably, said returning arrangement is coupled to at least two co-acting piston bodies for
mutually returning respective piston body to its starting point after fulfilled piston stroke.
Preferably, a resetting spring (e.g. a compression spring) arrangement is mounted to the
exterior of the cylinder housing and to the piston body, thereby acting as said returning
arrangement.
Suitably, the returning arrangement comprises a chain wheel device including a chain
arrangement mounted in engagement with respective first and second piston body in such
way that when the first piston body is propelled in one direction, the second piston body is
returned to its starting point and when the second piston body is propelled in said one
direction, the first piston body is returned to its starting point.
Preferably, the returning arrangement comprises a reverse motion linkage arrangement
provided for moving the first piston body in one direction when the second piston body is
moved in the opposite direction and vice versa.
Suitably, the reverse motion linkage arrangement comprises a flexible member for
compensating shifting momentum from propelling the first piston body to propelling the
second piston body. The shifting momentum is due when both piston bodies, or more than
two piston bodies, are engaged with the piston rod at the same time and may be provided
during a very short time period, such as 1 -10 milliseconds or more.
In such way is achieved cost-effective service and proper visual status detection of the
resetting springs.
The sleeve portion can be called "block portion", "engaging portion", "extended clamping
portion" of the piston body or other suitable term.
The respective first, second, third and fourth piston body being parts of a first, second, third
and fourth actuator means.
Preferably, the piston rod engagement and disengagement means is adapted to be activated
by said fluid supply device via a fluid connection arranged on a sleeve portion of the
respective piston body outside the cylinder housing.
In such way is achieved that direct fluid transfer for a clamping action is provided.
Suitably, the piston rod engagement and disengagement means is adapted to be activated
by said fluid supply device via a fluid connection arranged on the cylinder housing coupled to
a longitudinal groove in an interface between the piston body and the cylinder housing
interior, which groove is in fluid communication with the piston rod engagement and
disengagement means.
In such way is achieved that separate fluid transfer can be provided for a clamping action.
Preferably, the sensor device is arranged to the elongated fluid actuator arrangement for
determining an actual cylinder-piston feature value, a control unit is associated with the
sensor device and with the valve member means for controlling said engaging and
disengaging of the piston body to/from the piston rod member.
Thereby is achieved that a monitoring and control of the first piston body motion in the first
cylinder housing.
Thereby is achieved that monitoring and control of the second piston body motion in the
second cylinder housing.
Suitably, a sensor device is arranged to the elongated fluid actuator arrangement for
determining a piston rod member position value, a control unit is associated with the sensor
device and with the valve member means for controlling said engaging and disengaging of
the piston body to/from the piston rod member.
In such way is achieved that that the position of the piston rod member can be determined in
an effective way independently from the actual cylinder-piston feature value or in
combination with the actual cylinder-piston feature value.
Preferably, the sensor device comprises a linear potentiometer.
Suitably, the sensor device comprises an optical detector.
Preferably, the sensor device comprises an angular potentiometer.
Suitably, the sensor device comprises a pressure sensor.
Preferably, the control unit is adapted to control the valve member means from a desired
cylinder-piston feature value in regard to said determined actual cylinder-piston feature value
and/or said piston rod member position value, for regulating fluid flow fed from the fluid
supply device to the respective first and second cylinder chamber.
In such way is achieved that efficient control of the arrangement is achieved. Thereby is also
achieved that the control unit can be used to operate the arrangement in many various ways
in regard to actual operation and mode.
This is also solved by a method for controlling the motion of an elongated fluid actuator
arrangement including a first cylinder housing encompassing a first piston body comprising a
first piston rod engagement and disengagement means and dividing the first cylinder housing
in a first and second cylinder chamber coupled to a fluid supply via a valve member means, a
control unit is associated with a sensor device of the arrangement for determining an actual
cylinder-piston feature value and is coupled to said valve member means for regulating fluid
flow to said first cylinder housing, a piston rod extends through the first piston body, the
method comprises the steps of; providing a first actual cylinder-piston feature value to the
control unit; comparing the first actual cylinder-piston feature value with a first desired
cylinder-piston feature value; regulating fluid flow to the respective first and second cylinder
chamber; and repeating the preceding steps until the first actual cylinder-piston feature value
corresponds with the first desired cylinder-piston feature value.
In such way is achieved a precise and smooth motion of the piston rod member and
adaptability of the arrangement to different loads and working conditions.
Preferably, the arrangement further comprises a second cylinder housing encompassing a
second piston body comprising a second piston rod engagement and disengagement means
and dividing the second cylinder housing in a first and second cylinder chamber coupled to a
fluid supply via a valve member means, a control unit is associated with a sensor device of
the arrangement for determining an actual cylinder-piston feature value and is coupled to
said valve member means for regulating fluid flow to said second cylinder housing (5), a
piston rod extends through the second piston body, the method comprises the steps of;
pressurizing the first cylinder chamber of the first cylinder housing with a first fluid pressure
feature for engaging the first piston rod engagement and disengagement means to the piston
rod and driving the first piston body with the piston rod from a first start position to a first end
position; pressurizing the second cylinder housing of the second cylinder housing with a
second fluid pressure feature for disengaging the second piston rod engagement and
disengagement means from the piston rod and retracting the second piston body to a second
start position; pressurizing the first cylinder chamber of the second cylinder housing with the
first fluid pressure feature for engaging the second piston rod engagement and
disengagement means to the piston rod and driving the second piston body with the piston
rod from the second start position to a second end position; wherein said valve member
means is controlled to manage the second start position to precede said first end position
with an overlap time interval.
Thereby is achieved that a smooth performance and motion of the piston rod member can be
made.
Preferably, the time for retraction of the second piston body is shorter than the time for the
working stroke of the first piston body from the first start position to the first end position.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will now be described by way of examples with references to the
accompanying schematic drawings, of which:
Fig. 1 illustrates one aspect of the present invention;
Figs. 2a to 2b illustrate the arrangement in Fig. 1 in operation;
Fig. 3 illustrates a further aspect of the invention;
Figs. 4a to 4b illustrate further aspects of the invention;
Figs. 5a to 5d illustrate further aspects of the invention;
Figs. 6a to 6b illustrate a yet further aspects of the present invention;
Figs. 7a to 7b illustrate further aspects of the invention;
Figs. 8a to 8c illustrate an embodiment comprising a membrane cavity;
Fig. 9 illustrates one aspect of the invention;
Figs. 10a to 10d illustrate a method for operating an arrangement according to one aspect of
the present invention;
Figs. 11a to 11e illustrate a further aspect;
Figs. 12a to 12b illustrate yet a further aspect;
Fig. 13 illustrates an arrangement having separate fluid supply systems;
Fig. 14a illustrates an arrangement according to one example;
Figs. 14b-14c illustrate further examples of actuators;
Figs. 15a-15d illustrate a method of operating an arrangement; and
Fig. 16 illustrates schematic actuation of actuators as an example.
DETAILED DESCRIPTION
Hereinafter, embodiments of the present invention will be described in detail with reference
to the accompanying drawings, wherein for the sake of clarity and understanding of the
invention some details of no importance may be deleted from the drawings. The elongated
fluid actuator arrangement 1 is herein also called arrangement.
Fig. 1 schematically shows an elongated fluid actuator arrangement 1 comprising a first and
second cylinder housing 3 , 5 extending in a longitudinal direction X, respective cylinder
housing 3 , 5 encompasses a first 7 respective a second 9 piston body. The respective piston
body 7 , 9 divides the respective cylinder housing 3 , 5 in a first 11 and second 13 cylinder
chamber. The arrangement is adapted for connection to a valve member means 15 of a fluid
supply device 17. A control unit CPU is arranged for controlling the valve member means 15.
A piston rod 19 extends through the respective first 7 and second 9 piston bodies. The first
piston body 7 comprises a first protruding portion 2 1 protruding in a direction radially outward
and transverse to the longitudinal direction X. The first protruding portion 2 1 exhibits a first
diameter D1. Opposite cross-sectional piston areas 23, 25 are formed by plane surfaces of
the first protruding portion 2 1 extending transverse to the longitudinal direction X. The first
protruding portion 2 1 exhibits a first length L 1 in the longitudinal direction. The first piston
body 7 comprises a first sleeve portion 27 having a second diameter D2, which is smaller in
amount than the first diameter D1, seen in cross-section. The first sleeve portion 27 exhibits
a second length L2. The second length L2 comprises the first length L 1 and exhibits an
additional measure L3 (L3/2 + L3/2) according to the formula L2= L1+L3. The first sleeve
portion 27 comprises a piston rod engagement and disengagement means 29 adapted to be
operated by said fluid supply device 17 via said cylinder chambers 11, 13, which are
provided for fluid communication to a membrane cavity (see e.g. ref. 28 in Fig. 5a) formed in
the first sleeve portion 27 and constituting part of the piston rod engagement and
disengagement means 29. A resetting (returning) spring RS (e.g. a compression spring)
arrangement is provided to the exterior of the cylinder housing 3 with one end and to the first
piston body 7 with the other end. The second piston body 9 comprises a second protruding
body portion 22 having a third diameter D3 and a second sleeve portion 27" having a smaller
fourth measure D4. The first diameter D 1 corresponds with the third diameter D3.
Figs. 2a to 2b schematically show an upper 3 1 and lower 33 actuator of an arrangement 1 in
operation. The arrangement 1 comprises a pair of rigidly fixed cylinder housings 3 , 5 of
respective actuator 31, 33. Fig. 2a shows that the first piston body 7 of the upper actuator 3 1
is actuated by pressurizing the second cylinder chamber 13, wherein the piston rod
engagement and disengagement means 29 engages the first piston body 7 to the piston rod
19 for propelling the latter in a direction upward. In Fig. 2b is shown that the second cylinder
chamber 13 of the lower actuator 33 is pressurized propelling the second piston body 9
upwardly. No pressure is applied to the upper actuator 31, wherein the first piston body 7 of
the upper actuator 3 1 being released from the piston rod 19 by the inactive (not pressurized)
piston rod engagement and disengagement means 29 of the first piston body 7 . The piston
rod 19 has been propelled a distance Z in Fig. 2b. The operation proceeds in a smooth and
continuous manner with repeated steps until the arrangement is controlled to stop.
Fig. 3 illustrates a further aspect of the invention. A piston rod engagement and
disengagement means 29 of the arrangement 1 comprises a cavity 28 in the sleeve portion
27 and forming a membrane 30 positioned adjacent an inner surface 32 of the sleeve portion
27. The cavity 28 is arranged for fluid communication with respective cylinder chamber 11,
13 of a first cylinder housing 3 . The arrangement 1 further comprises a second and a third
cylinder housing 5", 5"' and therein arranged second and third piston body 9", 9"'. The third
cylinder housing 5"' thus encompasses the third piston body 9"' being arranged to a common
piston rod member 19. The second piston body 9" comprises a second piston rod
engagement and disengagement means 29" and the third piston body 9"' comprises a third
piston rod engagement and disengagement means 29"'.
A main fluid passage 35 is arranged for fluid communication with the cavity 28 and joins a
branch junction 37 diverging into a first 39 and second 4 1 passage arranged for fluid
communication with the respective cylinder chamber 11, 13. The respective first and second
passage 39, 4 1 ends at respective piston area 23, 25 at fluid ports facing the cylinder
chambers 11, 13. The first fluid passage 39 thus enters at the cross-sectional piston area 23
of the first cylinder chamber 11. By pressurizing the cavity 28 of the engagement and
disengagement means (comprising the membrane member 30) the latter will provide an
expansion of the inner surface 32 of the sleeve portion 27 in a direction radially inward. The
piston body 7 will thereby be clamped to the piston rod 19. The thickness T of the piston
material, which thickness is defined between the cavity 28 and an outer surface 34 of the
sleeve portion 27 exhibits such measure that no expansion of the outer surface 34 is
performed during said pressurization of the membrane member 30. At the same time, by said
pressurizing, the piston body is forced to move in direction Y . By said engagement of the
piston body 7 to the piston rod 17, the latter will be propelled in direction Z .
Figs. 4a to 4b illustrate further aspects of the invention. Fig. 4a illustrates a sleeve portion 27
having an inner surface 32 comprising grooves in a gridiron pattern 43 for enhanced
engagement performance. End stroke position is marked with E. Fig. 4b illustrates a sleeve
portion 27 having an inner surface 32 comprising grooves in helical pattern 42 for enhanced
engagement performance. The protruding body portion 2 1 and the sleeve portion 27 are
made in one piece. The second length L2 is larger than the cylinder housing 3 length HL in
said longitudinal direction X.
Figs. 5a to 5d illustrate further aspects of the invention. Fig. 5a illustrates a cross section of a
sleeve portion 27 in longitudinal direction. The inner surface 32 of the sleeve portion 27 is
provided with transversal grooves 44. Passages 39, 4 1 provide fluid communication between
the cylinder chambers (not shown) and a membrane cavity 28 via a shuttle valve 45, which
shuttle valve 45 is shown in an enlarged view in Fig. 5b.
Fig. 5c illustrates a flap valve 60 arranged for proper distribution of pressurized fluid from the
respective cylinder chamber to the cavity 28 depending upon which cylinder chamber being
pressurized. Fig. 5d illustrates an enlarged view of the flap valve 60 in Fig. 5c.
Fig. 6a illustrates a yet further aspect of the present invention. The arrangement 1 comprises
a first actuator 7 1 provided with a first cross-sectional piston area Ar1 , a second actuator 72
provided with a second cross-sectional piston area Ar2 corresponding with the first crosssectional
piston area Ar1 . It further comprises a third actuator 73 provided with a third crosssectional
piston area Ar3 and a fourth actuator 74 provided with a fourth cross-sectional
piston area Ar4. The third cross-sectional piston area Ar3 is twice as large as the first crosssectional
piston area Ar1 and the fourth cross-sectional piston area Ar4 is twice as large as
the third cross-sectional piston area Ar3. The effective force area of the arrangement 1 can
thus be changed in an optimal way by selected pressurization of suitable cylinder chambers
depending upon operational requirements. For e.g. providing fast piston motion and minor
force, the first cross-sectional piston area Ar1 (e.g. 1 area unit) is actuated. For achieving
slow piston motion with high force, all actuators 71, 72, 73, 74 are actuated. All four crosssectional
piston areas Ar1 , Ar2, Ar3 and Ar4 are used in such mode. This means that eight
area units are used, i.e. the force areas of the first, second, third, fourth actuators 71, 72, 73,
74 are all used together. This implies the provision of an optimal combination of eight
different force area units, which can be selected from required piston motion rate and force of
the arrangement 1.
Fig. 6b illustrates a complement functionality using a membrane 30 of a sleeve block BB
attached to a fundament or cylinder housing. The membrane 30 is autonomously pressurized
by a separate fluid pressure supply (not shown) in case of malfunction of the arrangement,
whereby a brake action is provided for stopping the piston rod 19 movement.
Figs. 7a to 7b illustrate further aspects of the invention. Fig. 7a illustrates an arrangement 1
comprising one piston body 7 comprising the piston rod engagement and disengagement
means 29. The sleeve portion 27 extends from one side of the piston body 7 , wherein the
opposite side is flat. The other piston of the arrangement 1 is rigidly fixed to the piston rod
19. By controlling the piston rod engagement and disengagement means 29 of the piston
body 7 , the arrangement 1 will have the capacity to add force or reduce force and thus exert
high force for specific operation. Fig. 7b illustrates an arrangement 1 comprising a first and
second piston body 7', 7" having plane sides (piston areas) facing each other and a cylinder
wall there between. The sleeve portions 27 comprising the respective piston rod engagement
and disengagement means 29 are extended in a direction away from each other. Such
arrangement 1 can be made less bulky at the same time as a relatively large engagement
area (achieving high friction between piston rod and piston body) will provide proper
engagement. The relatively large engagement area also implies that the fluid pressure can
be reduced within the piston rod engagement and disengagement means 29, which
decreases wear and tear of the arrangement 1, still reaching sufficient engaging force.
Figs. 8a to 8b schematically illustrate a piston rod engagement and disengagement means
29 in a view transverse to the longitudinal direction. Fig. 8a shows a first piston body 7 . A
bore 80 (exhibiting an inner wall section 81) is provided centrally in the piston body 7 for
encompassing a piston rod 19. An interior channel 82 is arranged in the piston body 7 , which
channel 82 is provided with six tangent section portions. The interior channel 82 is adapted
for fluid communication with a fluid pressurized cylinder chamber (not shown). Pressurized
fluid is fed into the interior channel 82 (membrane 30 cavity) from said cylinder chamber,
wherein the inner wall section 8 1 expands in a radial direction inwardly according to arrows
AR in Fig. 8b. In such way the piston body 7 will engage the piston rod 19. Fig. 8c shows a
longitudinal cross-section of a piston body 7 . Passages 39, 4 1 are in fluid communication
with a membrane cavity 28 via a shuttle valve 45. The piston body 7 is slidingly mounted in a
cylinder housing 3 . End stroke position is marked with E. The piston body 7 comprises an
inner casing 104 and outer housing 105. The inner casing 104 is releasable inserted into the
outer housing 105. The inner casing 104 is made of a bronze material constituting base
material. O-rings 103 are arranged at each side of the membrane cavity 28 formed by the
mutually facing areas of the inner casing 104 and outer housing 105. The inner surface of the
inner casing 104 surface facing the piston rod 19 exhibits a helical groove (not shown) for
achieving even friction and guaranteed engagement between the inner surface and the
piston rod 19. An end block 101 covers the membrane cavity 28 and is secured by bolts 102.
The helical groove also provides for removal of excessive lubricating oil. When the
membrane cavity 28 is pressurized, the inner casing 104 expands uniformly in radial
direction towards the piston rod 19 and provides rigid engagement with the piston rod 19.
When the pressure is released, the inner casing 104 reverts to its original measure. The
piston body 7 involves the requirement of a low hydraulic pressure for engagement and
securing the piston rod 19, frequently pressurizing, long distance movement along the piston
rod 19, rust resistant, no axial displacement of the piston body 7 when the membrane cavity
28 is pressurized. The working temperature of the piston body 7 in this embodiment is
between -30 up to + 110 degrees Celsius.
Fig. 9 shows one aspect of the present invention. The arrangement 1 comprises three piston
bodies 91', 91", 91"', each provided for engagement and disengagement from a piston rod
19 in a way similar to that has been described for previous embodiments. The arrangement 1
further comprises a first, second and third cylinder housing 3', 3", 3"' extending in a
longitudinal direction X. Each cylinder housing 3', 3", 3"' encompasses the respective piston
body 91', 91", 91"'. The respective piston body divides the respective cylinder housing 3', 3",
3"' in a first 11 and second 13 cylinder chamber. The arrangement 1 is adapted for
connection to a valve member means (not shown) of a fluid supply device (not shown). The
piston rod 19 extends through the piston bodies 91', 91", 91"'. The first piston body 91'
comprises a piston rod engagement and disengagement means 29, which is adapted to
engage or disengage the first piston body 91' to/from the piston rod 19, wherein an
engagement area A2 defined by the engagement between the first piston body 91' and the
piston rod 19 is larger than a cross-sectional piston area A 1 of the piston body 91'. The
cross-sectional piston area A 1 is defined as the area of the piston, which (effective area)
extends in a transverse direction to the longitudinal direction X. The amount of the force
generated by each cylinder depends upon the effective area of the piston body 91', 91", 91"'
and the fluid pressure in the utilized cylinder chamber ( 1 1 or 13). The engagement area A2 is
defined as an effective area determined by the engagement between the piston rod
engagement and disengagement means 29 comprising a central bore 80 (guiding or fixing
the piston rod 19) of the piston body 91', 91", 91"', which bore 80 extends transverse to the
extension of the cross-sectional piston area A 1 of each piston body 91', 91", 91"' and along
the longitudinal direction X. The cross-sectional piston area A 1 of the piston body respective
the engagement area A2 can be determined by the formulas:
Al = p * (ry 2 - r i 2 )
A2 = 2 * * r i * L
Where ry (see Fig. 9) is the outer radius of the piston body and ri (see Fig. 8a for example
illustration) is the radius of the central bore 80, L is the length of the central bore or piston rod
engagement and disengagement means seen in a direction along the longitudinal direction
X.
The piston body 91' exhibits an engagement area A2 being larger than the cross-sectional
area A1:
A2 > Al
It has surprisingly been shown by experiments of the applicant that the engagement of the
piston body to the piston rod in such way is enhanced for an arrangement using the same
fluid pressure for the piston rod engagement and disengagement means (e.g. membrane
member 30) as for the cylinder chamber comprising the effective piston area.
Figs. 10a to 10d schematically illustrate a method for operating the motion of a piston rod 19
of an arrangement 1 according to one aspect of the present invention. The arrangement 1
comprises a supply device 18 provided for controlled feeding of hydraulic fluid for
pressurizing the arrangement 1. The arrangement 1 comprises a first cylinder 3 and a
second cylinder 5 . A first piston body 7 is arranged in the first cylinder 3 and a second piston
body 9 is arranged in the second cylinder 5 . A spring mechanism (not shown) is arranged in
respective cylinder 3 , 5 for positioning respective piston body 7 , 9 symmetrically (seen in a
longitudinally direction between end walls of the cylinder) in the cylinder 3 , 5 , when
respective cylinder chamber 11, 13 not being pressurized. Each piston body 7 , 9 is provided
with a piston rod engagement and disengagement means (not shown) adapted to engage
(couple) or disengage (release) the piston bodies 7 , 9 to/from a common piston rod 19. A
pump PM is connected to a control valve 16, which in turn is connected to respective cylinder
chamber 11, 13 of the arrangement 1 via first and second logic valves 14', 14". The first
cylinder 3 is connected to the control valve 16 via the first logic valve 14' adapted for
directing the hydraulic flow to the respective cylinder chamber 11, 13 of the first cylinder 3 .
The second cylinder 5 is connected to the control valve 16 via the second logic valve 14"
adapted for directing the hydraulic flow to the respective cylinder chamber 11, 13 of the
second cylinder 5 . In Fig. 10b is shown that the first piston body 7 is actuated by pressurizing
the first cylinder chamber 11 of the first cylinder 3 (with a force FX1). This is made by
opening the control valve 16 and the first logic valve 14'. The direction of motion is operated
by controlling the control valve 16 and the actuating of the first piston body 7 is thus made by
operating the first logic valve 14'. By pressurizing the first cylinder chamber 11 of the first
cylinder 3 , the first piston body 7 engages the common piston rod 19 and propels the latter
by means of the piston rod engagement and disengagement means 29'. A membrane
member (not shown) of the piston rod engagement and disengagement means 29' is
pressurized for achieving said engagement. The piston rod 19 is moved a distance a 1 from
the starting reference point PX shown in Fig. 10a. In Fig. 10c is shown that the second piston
body 9 is actuated by pressurizing the first cylinder chamber 11 of the second cylinder 5 (with
a force FX2). The direction of motion is operated by controlling the control valve 16 and the
actuating of the second piston body 9 is made by operating the second logic valve 14". By
pressurizing the first cylinder chamber 11 of the second cylinder 5 , the second piston body 9
engages the common piston rod 19 by means of the piston rod engagement and
disengagement means 29". The piston rod 19 has in total made a distance a2 from the
starting reference point PX. The motion is performed continuously with a predetermined
velocity v and the first and second logic valves 14', 14" are adapted to regulate the fluid flow
to the respective first and second cylinders 3 , 5 in such way that a smooth motion of the
piston rod 19 is performed by alternately using the first and second logic valves 14', 14" and
providing said velocity. Both first cylinder chambers 11 of the respective first and second
cylinder 3 , 5 may simultaneously be pressurized (not shown) for achieving a larger force.
Fig. 10d shows that both first and second logic valves 14', 14" are turned off, wherein none
of the cylinder chambers 11, 13 being pressurized. The arrangement 1 is thus adapted for
disengaging both piston bodies 7 , 9 from the piston rod 19 for propelling the latter using the
kinetic energy of the mass (in a way reminding of a freewheel clutch) performing said
velocity.
Figs. 11a to 11e show one aspect using a linkage arrangement 120 of a returning
arrangement 121. The returning arrangement 121 is provided for returning first piston body 7'
to a starting point SP relatively its cylinder housing 3 , in which starting point SP the first
piston body 7' is engaged to the piston rod 19 for propelling the piston rod 19. The linkage
arrangement 120 is designed as a reverse motion linkage arrangement which is provided for
moving the first piston body 7' in one direction when the second piston body 7" is moved in
the opposite direction and vice versa. The linkage arrangement 120 comprises a flexible
member (not shown) for compensating instantaneously shifting momentum from propelling
the first piston body 7' to propelling the second piston body 7". The linkage arrangement 120
is coupled to the respective first and second piston bodies 7 . 7" for mutually returning
respective piston body 7',7" to its starting point after fulfilled piston stroke. Fig. 11a shows
that the second piston body 7" is actuated by the pressurized cylinder chamber 5 . The end of
the second piston body 7" facing the first piston body 7' is pivotally mounted to a first linkage
arm 125 which in turn is pivotally coupled to a pivoting central arm 126. The end of the first
piston body 7' facing the second piston body 7" is pivotally mounted to a second linkage arm
127, which in turn is pivotally coupled to the central arm 126. Fig. 11b shows that the first
piston body 7' is propelled by pressurized fluid, wherein the linkage arrangement 120
provides a movement of the second piston body 7" towards its starting point SP. In Fig. 11c
the second piston body 7" has reached the starting point by means of the action of the
linkage arrangement 120. During the shift of actuated piston body, both pistons being
actuated by pressurized fluid in respective fluid chamber in shifting (See Fig.1 1d) momentum
from propelling the first piston body 7' to propelling the second piston body 7". Fig. 11e
shows that the shifting is completed and that the second piston body 7" again is propelled
towards the first piston body T and the latter being moved towards the second piston body T
in a returning motion by means of the linkage arrangement 120.
Figs. 12a to 12b shows a returning arrangement comprising a chain wheel device 130
including a chain arrangement 131 mounted in engagement with respective first 7' and
second 7" piston body in such way that when the first piston body 7' is propelled in one
direction OD, the second piston body 7" is returned to its starting point SP and when the
second piston body 7" is propelled in said one direction OD, the first piston body 7' is
returned to its starting point SP. In Fig. 12a is shown that pressure PEE1 propels the first
piston body T and in Fig. 12b is shown that pressure PEE2 propels the second piston body
7" and mutually propels the piston rod 19 in one direction OD.
Fig. 13 illustrates an arrangement having separate fluid supply systems. A first fluid supply
and control system 140 is coupled to the respective membrane member (not shown) of the
piston bodies 7 . The membrane member is thus arranged in direct fluid communication with
the fluid supply, i.e. the pressurized fluid is fed directly into the respective protruding part
PPT (protruding from the cylinder housing 3) of the piston body 7 and membrane cavity for
pressurizing the membrane member and thereby provide engagement between the
respective piston body 7 and the piston rod 19. That is, the first fluid supply and control
supply system 140 used for the membrane member is separate from a second fluid supply
and control system 141 used for the actuating of the piston bodies 7 in the cylinder housings
via lines 149 for propelling the piston bodies 7 . A yet further separate fluid supply system 142
is provided for autonomous controlling braking action of the piston rod 19 by pressurizing a
separate membrane engaging a braking block DP3. The systems are in turn controlled and
monitored by a control processor unit CPU.
Fig. 14a illustrates an arrangement according to one example. The arrangement 1 comprises
two actuators 31', 31". A sensor device 201 is arranged to the elongated fluid actuator
arrangement 1 for determining an actual cylinder-piston feature value, a control unit CPU is
associated with the sensor device 201 and with the valve member means 15 for controlling
said engaging and disengaging of the respective piston body 7 , 9 to/from the piston rod
member 19 by means of an engagement and disengagement means 29. Thereby is
achieved that a monitoring and control of the first piston body motion in the first cylinder
housing and also monitoring and control of the second piston body motion in the second
cylinder housing. An engagement zone is defined as an engagement area corresponding
with the contact and clamping area of the first piston body 7 (or second piston body 9). I.e.
the area of the piston body which is in engagement with the piston rod 19 when the
respective piston body 7 , 9 is engaged. The measure of the engagement area e.g. has an
extension corresponding with the radially inward projected extension of a cavity of the piston
rod engagement and disengagement means 29. The cavity is co-axially arranged in the
piston body 7 , 9 and exhibits the same central axis as the cylinder housing 3 , 5 and the
piston rod 19 in the longitudinal direction. The cavity may be arranged for fluid
communication with the respective first and second cylinder chamber 11, 13 (alternately or
simultaneously). Optionally, a piston position sensor device 202 is arranged to the elongated
fluid actuator arrangement 1 for determining a piston rod member position value, a control
unit CPU is associated with the sensor device 202 and with the valve member means 15 for
controlling said engaging and disengaging of the piston body 7 to/from the piston rod
member 19. The control unit CPU is adapted to control the valve member means 15 from a
desired cylinder-piston feature value in regard to said determined actual cylinder-piston
feature value and/or said piston rod member position value, for regulating fluid flow fed from
the fluid supply device 17 to the respective first and second cylinder chamber 11, 13.
Figs. 14b-14c illustrate further examples of actuators 31. The piston rod engagement and
disengagement means 29 in Fig. 14b is adapted to be activated by said fluid supply device
(not shown) via a fluid connection 203 arranged on a sleeve portion 27 of the respective
piston body outside the cylinder housing 3 . In such way is achieved that direct fluid transfer
for a clamping action is provided. A micro-switch sensor 201' is arranged at the piston body
outer end and the cylinder housing cap end. The piston rod engagement and disengagement
means in Fig. 14c is adapted to be activated by said fluid supply device via a fluid connection
205 arranged on the cylinder housing and coupled to a longitudinal groove 207 in an
interface between the piston body and the cylinder housing interior, which groove 207 is in
fluid communication with the piston rod engagement and disengagement means. The
arrangement is provided with a pressure sensor PS for measuring the pressure difference
between the first and second cylinder chamber.
Figs. 15a-15d illustrate an example of a method of operating an arrangement 1. The method
is provided for controlling the motion of the elongated fluid actuator arrangement 1 including
a first cylinder housing 3 encompassing a first piston body 7 comprising a first piston rod
engagement and disengagement means 29' and dividing the first cylinder housing 3 in a first
and second cylinder chamber 11, 13 coupled to a fluid supply 17 via a valve member means
15, a control unit CPU is associated with a sensor device 201 of the arrangement 1 for
determining an actual cylinder-piston feature value and is coupled to said valve member
means 15 for regulating fluid flow to said first cylinder housing 3 . A piston rod 19 extends
through the first piston body 7 . The method includes the steps of providing a first actual
cylinder-piston feature value to the control unit CPU and furthermore comparing the first
actual cylinder-piston feature value with a first desired cylinder-piston feature value. It
comprises also the steps of regulating fluid flow to the respective first and second cylinder
chamber 11, 13 and repeating the preceding steps until the first actual cylinder-piston feature
value corresponds with the first desired cylinder-piston feature value. The arrangement 1
further comprises a second cylinder housing 5 encompassing a second piston body 9
comprising a second piston rod engagement and disengagement means 29" and dividing the
second cylinder housing 5 in a first and second cylinder chamber 11, 13 coupled to said fluid
supply 17 via the valve member means 15. The control unit CPU is associated with a further
sensor device 201 (linear potentiometer attached to the second cylinder housing 5) for
determining an actual cylinder-piston feature value and is coupled to said valve member
means 15 for regulating fluid flow to said second cylinder housing 5 . The method includes
pressurizing the first cylinder chamber 11 of the first cylinder housing 3 with a first fluid
pressure feature for engaging the first piston rod engagement and disengagement means 29'
to the piston rod 19 and driving the first piston body 7 with the piston rod 19 from a first start
position (S1 , see Fig. 16) to a first end position E 1 (See Fig. 16). The method further
comprises the steps of pressurizing the second cylinder chamber 13 of the second cylinder
housing 5 with a second fluid pressure feature for disengaging the second piston rod
engagement and disengagement means 29" from the piston rod 19 and retracting the
second piston body 9 to a second start position S2 (see Fig. 16) and pressurizing the first
cylinder chamber 11 of the second cylinder housing 5 with the first fluid pressure feature for
engaging the second piston rod engagement and disengagement means 29" to the piston
rod 19 and driving the second piston body 9 with the piston rod 19 from the second start
position S2 to a second end position E2 (see Fig. 16). The valve member means 15 is
controlled to manage the second start position S2 to precede said first end position E 1 with
an overlap time interval. In Fig. 15a the first piston body 7 propels the piston rod 19 at the
same time as the second piston body 9 is retracted. The motion and rates of the respective
piston body being controlled by the control unit CPU. In Fig. 16b the first piston body 7
reaches the first end position and the second piston body 9 reaches the second start
position. In Fig. 16c is shown the position wherein the piston bodies 7 , 9 drive the piston rod
in said overlap time interval for achieving smooth performance of the arrangement 1. In Fig.
15d is shown that the second piston body 9 propels the piston rod 19 at the same time as the
first piston body 7 is retracted. The motion and rates of the respective piston body being
controlled by the control unit CPU.
Fig. 16 illustrates schematic actuation scheme of actuators as an example. P marks fluid
pressure applied to the first C1-1 and the second C1-2 cylinder chamber of the first cylinder
housing and also the pressure applied to the engagement and disengagement means of the
first piston body of the first cylinder housing by controlling the valve member means (e.g.
reference 15) by means of commands from the control unit CPU in regards from signals fed
from sensors mounted to the cylinder housings. The levels of the pressure may fluctuate due
to various loads on the piston rod etc. T marks time. The first cylinder chamber C1-1 of the
first cylinder housing is pressurized as well as the engagement and disengagement means of
the first piston body for clamping action and driving of the first piston body (with the piston
rod) from a first start position S 1 to a first end position E1. Thereafter, the second cylinder
chamber C1-2 of the first cylinder housing is pressurized with a lower pressure LP for
retraction of the piston body back to the first start position S1, wherein the engagement and
disengagement means being controlled during said retraction to disengage the first piston
body from the piston rod. During propulsion of the first piston body from the first start position
S 1 to the first end position E1, the second piston body of the second cylinder housing is
retracted R. The time for retraction of the second piston body is shorter than the time for the
working stroke of the first piston body from the first start position S 1 to the first end position
E 1. The second start position S2 of the second piston body precedes the first end position of
the working stroke of the first piston body. The working stroke of the second piston body
prevails from the second starting position S2 to the second end position E2. In the same
way, subsequently, the first start position S 1 of first piston body precedes the second end
position E2 of the working stroke of the second piston body for providing an overlap time
interval. The time for retraction of the first piston body is shorter than the time for the working
stroke of the second piston body from the second start position S2 to the second end
position E2.
The present invention is of course not in any way restricted to the preferred embodiments
described above, but many possibilities to modifications, or combinations of the described
embodiments, thereof should be apparent to a person with ordinary skill in the art without
departing from the basic idea of the invention as defined in the appended claims. The valve
member means may comprise a logic valve of suitable type. The valve member may
comprise a 5 ports/2 valve positions unit, so called 5/2 valve or others. The valve member
may comprise a two-way valve of any type suitable for the arrangement. The shuttle valve
may be replaced by any other suitable type of valves for fulfilling the functionality of
pressurizing the piston rod engagement and disengagement means in view of pressurizing
one cylinder chamber at the time. The manoeuvring of the valve member may be performed
by means of a solenoid connected to a control unit adapted for controlling the valve member
and thereby the arrangement. The arrangement may be adapted for fast and high clamp
force engagement of the piston device for propelling the latter accurate also for acceleration
of heavy loads. The selection of material is possible in many ways. For example, aluminium
bronze or other compositions are possible. A variety of alloying agents such as iron, nickel,
manganese can be added to the aluminium bronze. Stainless steel, chrome steel or similar
material is also possible as material for the piston body and cylinder housing and piston rod.
By manoeuvring the valve member, such as a logical valve, the same arrangement can
perform also lower force and slow motion rate of the piston rod arrangement. A logical valve
can be manoeuvred by the control unit to shut down the fluid flow to excluded
cylinder/cylinders and only direct fluid flow to only one cylinder. There are different types of
valves that can be used for providing the above-mentioned aspects and other aspects.
Electro-hydraulic controlled valves or other types of directly controlled electro-hydraulic
logical valves, etc. can be used. The arrangement can be put into use in civil and military,
manned and unmanned aircraft: Leading/Trailing Edge Flap Actuators; Landing Gear
Actuators; Air Brakes; Primary Servo Actuators (PSA); Electro- Hydrical Actuator (EHA)
applications etc. The fluid can be hydraulic oil, gas or other. The invention may belong to any
of the segments; construction industry, jacking systems for oil well drilling and service
platforms, agricultural equipment industry, marine industry, crane manufacture industry.

CLAIMS
An elongated fluid actuator arrangement comprising:
-a first and second cylinder housing (3, 5) extending in a longitudinal direction (X),
respective cylinder housing (3, 5) encompasses a first respective a second piston
body (7, 9);
-the respective piston body (7, 9) divides the respective cylinder housing (3, 5) in a
first and second cylinder chamber ( 1 1, 13);
-the arrangement (1) being adapted for connection to a valve member means (15) of
a fluid supply device (17);
-a piston rod member (19) extending through said respective first and second piston
bodies (7, 9);
characterized by that
the first piston body (7) comprises a piston rod engagement and disengagement
means (29), which is adapted to engage or disengage the first piston body (7) to/from
the piston rod member (19), wherein an engagement area (A2), defined by an
engagement zone between the first piston body (7) and the piston rod member (19),
is larger than a cross-sectional piston area (A1) of the first piston body (7).
The arrangement according to claim 1, wherein the first piston body (7) comprises:
-a first protruding portion (21) protruding in a direction radially outward with a first
measure (D1) and defining opposite cross-sectional piston areas (23, 25); and
exhibiting a first length (L1) in said longitudinal direction (X),
-a first sleeve portion (27) having in cross-section a smaller second measure (D2)
than the first measure (D1); and with an additional measure (L3) to the first length
(L1) defining a second length (L2);
-said first sleeve portion (27) comprises the piston rod engagement and
disengagement means (29) adapted to be operated by said fluid supply device (17).
The arrangement according to claim 1 or 2 , wherein the piston rod engagement and
disengagement means (29) is adapted to be operated by said fluid supply device (17)
via said cylinder chambers ( 1 1, 13).
4 . The arrangement according to any of claim 1 to 3 , wherein the piston rod
engagement and disengagement means (29) comprises a cavity (28) in a first sleeve
portion (27) and forming a membrane member (30), which cavity (28) is arranged for
fluid communication with respective cylinder chamber ( 1 1, 13).
5 . The arrangement according to any of the preceding claims, wherein a main fluid
passage (35) is arranged for fluid communication with the piston rod engagement and
disengagement means (29) and joins a branch junction (37, 45, 60) diverging into a
first and second fluid passage (39, 41) arranged for fluid communication with the
respective cylinder chamber ( 1 1, 13).
6 . The arrangement according to claim 5 , wherein at least the first fluid passage (39)
enters at the cross-sectional piston area (23) of the first cylinder chamber ( 1 1).
7 . The arrangement according to any of the preceding claims, wherein the protruding
portion (21) and the sleeve portion (27) are made in one piece.
8 . The arrangement according to any of the preceding claims, wherein the second
piston body (9) comprises a second piston rod engagement and disengagement
means (29").
9 . The arrangement according to claim 8 , wherein the second piston body (9)
comprises a second protruding portion (22) having a third measure (D3) and a
second sleeve portion (27") having a smaller fourth measure (D4).
10. The arrangement according to claim 9 , wherein the first (D1) measure corresponds
with the third (D3) measure.
11. The arrangement according to any of the preceding claims, wherein the first piston
body (7) exhibits a second length (L2) that is larger than a cylinder housing length
(HL) of the first cylinder housing in said longitudinal direction (X).
12. The arrangement according to any of the preceding claims, wherein a third cylinder
housing (3"') encompassing a third piston body (91"') is arranged to said piston rod
member (19), the third piston body (91"') comprises a third piston rod engagement
and disengagement means (29"').
13. The arrangement according to any of the preceding claims, wherein a first crosssectional
piston area (Ar1) of the first piston body (72) differs in measure from a
second cross-sectional piston area (Ar3) of the second piston body (73).
14. The arrangement according to any of the preceding claims, wherein the
arrangement comprises a first piston body (72) provided with a first cross-sectional
piston area (Ar1), a second piston body (73) provided with a second cross-sectional
piston area (Ar2) corresponding with the first cross-sectional piston area (Ar1), a third
piston body (73) provided with a third cross-sectional piston area (Ar3), a fourth
piston body (74) provided with a fourth cross-sectional piston area (Ar4), the third
cross-sectional piston area (Ar3) is twice as large as the first cross-sectional piston
area (Ar1), the fourth cross-sectional piston area (Ar4) is twice as large as the third
cross-sectional piston area (Ar3).
15. The arrangement according to any of the preceding claims, wherein the
arrangement (1) is provided with a returning arrangement (RS, 121, 130) provided for
returning at least one piston body (7) to a starting point (SP) relatively its cylinder
housing (3), in which starting point (SP) the piston body (7) being arranged for
engagement with the piston rod (19) for propelling the piston rod (19).
16. The arrangement according to any of the preceding claims, wherein the
arrangement (1) is adapted to a lift system or a high bay storage system.
17. The arrangement according to any of the preceding claims, wherein the piston rod
engagement and disengagement means (29) is adapted to be activated by said fluid
supply device (17) via a fluid connection arranged on a sleeve portion (27) of the
respective piston body (7, 9) outside the cylinder housing (3, 5).
18. The arrangement according to any of the preceding claims, wherein the piston rod
engagement and disengagement means (29) is adapted to be activated by said fluid
supply device (17) via a fluid connection arranged on the cylinder housing (3) coupled
to a longitudinal groove in an interface between the piston body and the cylinder
housing interior, which groove is in fluid communication with the piston rod
engagement and disengagement means (29).
19. The arrangement according to any of the preceding claims, wherein a sensor device
is arranged to the elongated fluid actuator arrangement (1) for determining an actual
cylinder-piston feature value, a control unit (CPU) is associated with the sensor
device and with the valve member means (15) for controlling said engaging and
disengaging of the piston body (7) to/from the piston rod member (19).
20. The arrangement according to any of the preceding claims, wherein a sensor device
is arranged to the elongated fluid actuator arrangement (1) for determining a piston
rod member position value, a control unit (CPU) is associated with the sensor device
and with the valve member means (15) for controlling said engaging and disengaging
of the piston body (7) to/from the piston rod member (19).
2 1. The arrangement according to claim 19 or 20, wherein the control unit (CPU) is
adapted to control the valve member means (15) from a desired cylinder-piston
feature value in regard to said determined actual cylinder-piston feature value and/or
said piston rod member position value, for regulating fluid flow fed from the fluid
supply device (17) to the respective first and second cylinder chamber ( 1 1, 13).
22. A method for controlling the motion of an elongated fluid actuator arrangement (1)
including a first cylinder housing (3) encompassing a first piston body (7) comprising
a first piston rod engagement and disengagement means (29') and dividing the first
cylinder housing (3) in a first and second cylinder chamber ( 1 1, 13) coupled to a fluid
supply (17) via a valve member means (15), a control unit (CPU) is associated with a
sensor device (201) of the arrangement (1) for determining an actual cylinder-piston
feature value and is coupled to said valve member means (15) for regulating fluid flow
to said first cylinder housing (3), a piston rod (19) extends through the first piston
body(7), the method comprises the steps of:
-providing a first actual cylinder-piston feature value to the control unit (CPU);
-comparing the first actual cylinder-piston feature value with a first desired cylinderpiston
feature value;
-regulating fluid flow to the respective first and second cylinder chamber ( 1 1, 13); and
-repeating the preceding steps until the first actual cylinder-piston feature value
corresponds with the first desired cylinder-piston feature value.
23. The method according to claim 22, wherein the arrangement (1) further comprises a
second cylinder housing (5) encompassing a second piston body (9) comprising a
second piston rod engagement and disengagement means (29") and dividing the
second cylinder housing (5) in a first and second cylinder chamber ( 11, 13) coupled
to a fluid supply (17) via a valve member means (15), a control unit (CPU) is
associated with a sensor device (201) of the arrangement (1) for determining an
actual cylinder-piston feature value and is coupled to said valve member means (15)
for regulating fluid flow to said second cylinder housing (5), a piston rod (19) extends
through the second piston body (9), the method comprises the steps of:
-pressurizing the first cylinder chamber ( 1 1) of the first cylinder housing (3) with a first
fluid pressure feature for engaging the first piston rod engagement and
disengagement means (29') to the piston rod (19) and driving the first piston body (7)
with the piston rod (19) from a first start position (S1) to a first end position (E1);
-pressurizing the second cylinder housing (5) of the second cylinder housing (5) with
a second fluid pressure feature for disengaging the second piston rod engagement
and disengagement means (29") from the piston rod (19) and retracting the second
piston body (9) to a second start position (S2);
-pressurizing the first cylinder chamber ( 1 1) of the second cylinder housing (5) with
the first fluid pressure feature for engaging the second piston rod engagement and
disengagement means (29") to the piston rod (19) and driving the second piston body
(9) with the piston rod (19) from the second start position (S2) to a second end
position (E2); wherein said valve member means (15) is controlled to manage the
second start position (S2) to precede said first end position (E1) with an overlap time
interval.