Specification
Title: A filter assembly, a filter element, and a method for replacing a filter element
The present invention relates to a filter assembly used, for example, in a fluid
recirculation system of a hydraulic circuit or the like, in order to catch foreign matter,
contaminants, polyethanes and the like in the fluid. A filter assembly of this type may, for
example, be used to filter oil of a lubrication system or a hydraulic system of a crane. The oil
may be forced through the system by a pump. The pump can be driven by an electrical motor
or a combustion engine such as a diesel engine.
A filter assembly for filtering a fluid is known from a variety of applications including
hydraulic systems, fuel systems and engine lubrication systems. The filter assembly is
provided with a replaceable filter element that can be accommodated in a filter housing. The
filter housing is removably connected to a head, for example by screwing. The head has an
inlet and an outlet. The fluid flows into the inlet of the head into the filter housing, passes
through the filter element and flows out from the outlet of the head, so that any foreign
material and the like within the fluid is caught and removed by the filter element as the fluid
passes through the filter element.
The fluid to be filtered may enter the annular space between the filter element and
the housing via the inlet in the head, after which the fluid is distributed along the outer
circumferential surface of the filter element. The fluid then flows radially inward through the
filter element whereby contaminants in the fluid are captured by the filter element. The
filtered fluid subsequently flows to the outlet of the head. Alternatively, the flow may be
reversed i.e. the contaminated fluid enters the interior of the filter element and is then forced
through the filter element, thereby flowing substantially radially outward
With use, the filter element undergoes gradual degradation of its performance due
to clogging. The filter element may become clogged to the extent that it causes a problem in
the hydraulic system, such as inadequate flow to components downstream of the filter,
excessive pressures upstream of the filter element, and/or damage to the filter element
allowing the accumulated contaminants to flow to components downstream of the filter
element. This can be avoided by periodic replacement of the filter element or after the need
for replacement has been brought to the attention of an operator of the system. Thus, the
filter element of the filter assembly is replaced regularly.
The filter element is locked within the filter housing in operation. When replacing the
filter element by a new filter element, the filter housing is disassembled from the head and
the filter element is removed. This can be relatively difficult and also there are problems that
arise with respect to environmental concerns. Nowadays, according to prior art, the filter
element stays attached to the head when the filter housing is removed from the head. Only
after removing the filter housing, the filter element can be disconnected and removed from
the head. Taking into account the length of the filter element and housing this obviously
requires a large removal height. Under the housing a free space of approximately the axial
length of the filter element is required in order to be able to remove the housing. After
removing the housing, subsequent removal of the filter element from the head is hindered by
the filter element being wet and slippery from oil whilst large forces are required for removing
the (still attached) filter element from the head. Removal or displacement of the filter element
thus is complicated. A further disadvantage of the filter element initially staying attached to
the head is that oil drips from the filter element onto a machine or floor below it.
The object of the invention is to provide a filter assembly which can be replaced in a
simple manner.
Said object is achieved according to the invention by a filter assembly, comprising a
head, a filter housing which can be removably connected to the head, and a filter element
which can be received in the filter housing,
• the filter element comprising:
o a tubular wall provided with a filtration medium;
o a first end part provided at a first axial end of the filter element; and
o a second end part provided at a second axial end (30) of the filter element;
• the filter housing comprising a first axial end and a second axial end, wherein the first
axial end is provided with a first rotational connector part;
• the head comprising a second rotational connector part which can be removably engaged
by the first rotational connector parts,
wherein the housing can be connected to the head by rotating the housing with respect to the
head in a first direction of rotation and wherein the housing can be detached from the head
by rotating the housing with respect to the head in a second direction of rotation, the second
direction of rotation being opposite to the first direction of rotation;
wherein the second end part of the filter element and the second axial end of the filter
housing are provided with a locking assembly comprising:
• an opening provided at one of either the filter element or the filter housing; and
• a protrusion provided at the other one of either the filter element or the filter housing
which is adapted to project in the opening;
wherein the opening comprises a mouth which opens in axial direction, which mouth is,
viewed in tangential direction, wider than, viewed in tangential direction, the protrusion for
allowing the protrusion to enter into the opening when inserting the filter element, with its
second end part directed to the second axial end of the filter housing, axially into the housing
and for allowing the protrusion to be withdrawn from the opening when removing the filter
element axially out of the housing;
wherein the opening comprises a sloping side wall face sloping with respect to the axial
direction, which sloping side wall face, viewed in axial direction from the mouth into the
opening, widens said opening such that, when the protrusion has been received in the
opening and is withdrawn axially from the opening, the sloping side wall face guides the
protrusion in the second direction of rotation out of the mouth.
The opening (further also called 'undercut' opening) is by virtue of the sloping side wall face
'undercut', i.e. the opening has at least one portion which is, viewed parallel to the mouth,
wider than the mouth. The undercut opening provides that engagement between the
housing and filter element is possible and that, after removing the housing and filter element
together from the head, the filter element can easily be removed from the housing by just
exerting an axial pulling force. The sloping side wall face ensures that the protrusion is - if
not already aligned in front of the mouth of the opening - guided to the mouth of the opening
to allow leaving the opening through the mouth.
It is noted that the first rotational connector part and second rotational connector part
may according to the invention comprise mutually mating screw threads. Taking into account
that with screw threads the clockwise direction is in general the fixation direction and the
anti-clockwise direction is in general the loosening direction, the first rotational direction will
in case of screw threads in general be the clockwise direction (viewed from the second axial
end of the filter housing to the first axial end of the filter housing), whilst the second
rotational direction then will be the anti-clockwise direction. With screw thread pitched in
opposite direction, this will however be the other way around.
According to a further embodiment of the invention, the side of the protrusion facing
the sloping side wall face of the opening is provided with a sloping protrusion face having a
slope (a) which corresponds to the slope (a) of the sloping side wall face. This improves on
the one hand guiding of the protrusion to the mouth when removing the filter element from
the housing, whilst on the other hand it improves engagement between the sloping side wall
face and the protrusion.
According to a further embodiment of the invention, the slope of the side wall face -
and if present also the slope of the sloping protrusion face - is in the range of 20° - 40°,
such as about 30°, with respect to the axial direction. This provides both good engagement
and guiding function.
According to the invention it is either - first configuration - possible to provide the filter
element with the protrusion and the housing with the opening, or - second configuration - to
provide the housing with the opening an over the first configuration in that a slimmer design
with less use of material becomes possible. In a further embodiment of this first
configuration, the sloping side wall face of the opening is, viewed in axial direction from the
second end part of the filter element to the first end part of the filter element, arranged at that
side of the opening which faces, with respect to the longitudinal axis of the filter element, in
said second direction of rotation. Claim 4 claims this same further embodiment worded in
different manner. In a further embodiment of the second configuration, the sloping side wall
face of the opening is, viewed in axial direction from the second end part of the filter element
to the first end part of the filter element, arranged at that side of the opening which faces,
with respect to the longitudinal axis of the filter element, in said first direction of rotation.
Claim 5 claims this same further embodiment worded in different manner. Both the further
embodiment of the first configuration and the further embodiment of the second
configuration, provide that when removing the filter housing from the head by rotating the
housing with respect to the head in the second direction of rotation, the filter element is
drawn tight towards the second axial end of the filter housing by tangential engagement of
the sloping side wall face of the opening with the protrusion. Thus, the filter housing is
removed from the head easily together with the filter element, which stays accommodated in
the filter housing. The required removal height for removing the housing is hereby
considerably reduced. This removal height can even be. reduced up to the axial extension
height of the screw thread. Further dripping problems are avoided as dripping from the filter
element is collected in the housing. Further removal of the filter element from the housing is
easy and requires only low axial forces, as explained earlier.
When a fijter element is to be replaced in the filter assembly according to the
invention, the following procedure can be carried out.
In an operating condition, the filter housing is connected to the head and the filter
element has been received in the filter housing with the protrusion projecting in the opening.
The filter housing comprises a cylindrical body which is adapted to receive the hollow interior
of the filter element. When the housing is not attached to the head, the filter element can be
rotated with respect to the cylindrical body of the filter housing in order to align the protrusion
with the mouth of the opening for allowing the protrusion to be received in the opening. The
protrusion and undercut opening are configured to allow tangential movement of the
protrusion with respect to the opening such that, when the protrusion has been received in
the opening, the protrusion is movable between a position in which the protrusion is aligned
with the mouth of the opening and a position in which the protrusion, viewed in axial
direction, overlaps at least partially with the sloping side wall face.
For replacing the filter element, the filter housing is removed from the head by rotating
the housing with respect to the head in the second direction of rotation, in which the filter
element is drawn tight towards the second axial end of the filter housing by tangential
engagement of the sloping side wall face of the opening with the protrusion. Thus, the filter
housing is removed from the head easily together with the filter element accommodated in
the filter housing.
Then, the filter element is removed from the housing in axial direction by pulling the
filter element in axial direction away from the second axial end of the housing so that the
protrusion is withdrawn axially from the opening through the mouth. The opening is undercut,
i.e. the opening extending from the mouth has at least one portion which is wider than the
mouth. When withdrawing the protrusion axially from the opening, the protrusion will be
guided to the mouth as a result of the sloping side wall face. The sloping side wall face forces
the protrusion and opening to rotate slightly with respect to each other when withdrawing the
protrusion axially from the opening. Thus, when exerting a pulling force in axial direction only,
the sloping side wall face will guarantee that the protrusion is guided to the mouth of the
opening. The filter element can be removed from the filter housing in a simple and reliable
manner. There is no need for heavy turning and puling as required by prior art constructions
or in case of a regular bajonet closure between filter element and housing.
Next, a new filter element can be inserted axially into the housing and the filter
housing with the accommodated new filter element is connected to the head by rotating the
housing with respect to the head in the first direction of rotation. In case the protrusion is not
already received in the opening, rotating the housing with respect to the head in the first
direction will - due to friction between the filter element and the head - align the protrusion
axially with the mouth and the protrusion axially enters into the opening through the mouth.
After the protrusion entering the opening, the new filter element is in rotational direction
locked with respect to the filter housing.
In an embodiment the side of the protrusion facing the sloping side wall face of the
opening is provided with a sloping protrusion face having a slope which corresponds to the
slope of the sloping side wall face. In this case, the sloping side wall face of the opening and
the corresponding sloping protrusion face provide a reliable locking assembly which allows
smooth removal of the filter element from the filter housing at the same time.
It is possible that the slope of the side wall face is in the range of 20° - 40°, like about
30°, with respect to the axial direction. However, the slope of the side wall face can be
designed in a different manner.
In an embodiment the filter element is provided with the protrusion, wherein the filter
housing is provided with the opening, wherein the mouth opens into the direction of the first
axial end of the filter housing, and wherein the sloping side wall face, viewed from the
second axial end to the first axial end, slopes in the second direction of rotation such that,
when the filter housing is being removed from the head by rotating the housing with respect
to the head in the second direction of rotation, the filter element is drawn tight towards the
second axial end of the filter housing by engagement of the sloping side wall face of the
opening with the protrusion.
Alternatively, the filter element is provided with the opening, wherein the filter housing
is provided with the protrusion, and wherein the mouth opens into the direction of the second
axial end of the filter housing, and wherein the sloping side wall face, viewed from the first
axial end to the second axial end, slopes in the first direction of rotation such that, when the
filter housing is being removed from the head by rotating the housing with respect to the
head in the second direction (B) of rotation, the filter element is drawn tight towards the
second axial end (18) of the filter housing (15) by engagement of the sloping side wall face
(24) of the opening (21) with the protrusion (22).
In an embodiment the opening is provided in a ring shaped wall, wherein, viewed in
tangential direction, the mouth has a first side where the sloping side wall face is provided
and an opposing second side; and wherein the ring shaped wall is provided with an axial
projection, the axial projection being arranged adjacent the mouth at the second side of the
mouth. The second side of the opening might extend essentially in axial direction. As a result,
when the filter element is rotated with respect to the filter housing, the axial projection forms
a stop for aligning the protrusion and the opening with respect to each other. Thus, when
inserting a filter element in the filter housing, it can be detected that the protrusion and the
opening are aligned in the right manner without the protrusion and opening being visible.
In that case, it is possible that the ring shaped wall has an axially facing front face,
which is shaped with a pitch angle, the pitch angle being preferably at most 10°. The axially
facing front face thus extends like about one revolution of a screw thread. The pitch angle
virtually increases the height of the axial projection, so that the axial projection can remain
relatively small while still being able to stop the protrusion when rotating the filter element
with respect to the housing.
In an embodiment the projection has a guide surface for guiding the protrusion over
the projection when the protrusion moves over the projection from its side opposing the side
adjacent the mouth towards the mouth. When rotating the filter element with respect to the
housing in the first direction of rotation, the protrusion follows the front face of the ring
shaped wall and runs up along the guide surface of the projection. The protrusion moves
axially into the opening immediately behind the projection.
In an embodiment the second end part of the filter element is provided with a sealing
ring, such as an O-ring, having a ring axis perpendicular to a sealing ring plane defined by
the sealing ring, wherein the ring axis and the longitudinal axis of the filter element extend at
an acute angle with respect to each other, preferably in the range of 4-15°, and wherein the
filter housing is provided at its second axial end with a sealing seat which is adapted to the
sealing ring for sealing the interior of the filter element with respect to the second axial end of
the filter housing. This embodiment with inclined sealing ring reduces friction when removing
a filter element from the housing and placing the filter element into the housing. Further, it
appears that, an inclined sealing ring of this type has improved sealing properties in
comparison to a sealing ring having a ring axis coinciding with the longitudinal axis of the
filter element.
In an embodiment the sealing seat faces radially; wherein a ring front face facing
axially towards the first axial end adjoins the sealing seat; wherein the ring front face defines
a ring front face plane; and wherein, when the protrusion has been received in the opening,
the ring front face plane is parallel to the sealing ring plane. The sealing ring seals off the
interior of the filter element with respect to the second axial end of the filter housing when the
protrusion has been accommodated in the opening. When the filter element is rotated from
this angular position with respect to the filter housing, the sealing of the sealing is broken.
When the protrusion is not aligned with the mouth of the opening, the sealing ring will only
partly engage the sealing seat - if contacting it at all -. Consequently the sealing ring will not
be stretched but still be in a relaxed state, which in turn means that wear of the sealing ring
due to rotation of the sealing ring with respect to the sealing seat is reduced.
In an embodiment, the sealing ring is at a distance from the sealing seat when the
protrusion has been axially aligned with the mouth and positioned outside the opening
directly adjacent the mouth. The sealing ring seals off only after the protrusion has been
accommodated in the mouth.
The invention also relates to a filter element comprising:
o a tubular wall provided with a filtration medium;
o a first end part provided at a first axial end of the filter element; and
o a second end part provided at a second axial end of the filter element;
wherein the second end part of the filter element is provided with a protrusion, and wherein a
side of the protrusion is provided with a sloping protrusion face which slopes at a slope with
respect to the axial direction of the filter element. According to a further embodiment of this
filter element according to the invention the sloping protrusion face is, viewed in axial
direction from the second end part of the filter element to the first end part of the filter
element, arranged at that side of the protrusion which faces, tangentially with respect to the
longitudinal axis of the filter element, in clock-wise direction.
Furthermore, the invention relates to a filter element comprising:
o a tubular wall provided with a filtration medium;
o a first end part provided at a first axial end of the filter element; and
o a second end part provided at a second axial end of the filter element;
wherein the second end part of the filter element is provided with an opening which
comprises a mouth which opens in axial direction, and wherein the opening is, viewed from
the mouth, undercut, and wherein the opening comprises a sloping side wall face which
slopes at a slope with respect to the axial direction of the filter element, and wherein the
sloping side wall face, viewed in axial direction from the mouth into the opening, widens said
opening. According to a further embodiment of this filter element according to the invention
the sloping side wall face is, viewed in axial direction from the second end part of the filter
element to the first end part of the filter element, arranged at that side of the opening which
faces, tangentially with respect to the longitudinal axis of the filter element, in clock-wise
direction.
These filter elements can be adapted for insertion into a filter housing of a filter
assembly as described above. The filter housing comprises a first axial end and a second
axial end. The first axial end is provided with a first rotational connector part which can be
removably engaged with a second rotational connector part of a head for attaching the filter
housing to the head by rotating the filter housing with respect to the head in a first direction of
rotation and for detaching the housing from the head by rotating the filter housing with
respect to the head in a second direction of rotation. The second direction of rotation is
opposite to the first direction of rotation.
The second end part of the filter element comprises either an opening or a protrusion.,
In addition, the second end part of the filter housing is provided with a protrusion or an
opening which is adapted to engage with the opening or the protrusion of the filter element,
respectively, for locking the filter element and the filter housing with respect to each other.
In an embodiment, the filter element is provided with the protrusion and the filter
housing comprises the opening. The side of the protrusion facing the sloping side wall face of
the opening is provided with a sloping protrusion face having a slope which corresponds to
the slope of the sloping side wall face.
Alternatively, the filter element can be provided with the opening, in which case the
filter housing comprises the protrusion. The opening has a mouth which opens in axial
direction towards the second axial end of the filter element. The mouth is, viewed in
tangential direction, wider than, viewed in tangential direction, the protrusion of the filter
housing for allowing the protrusion to enter into the opening when inserting the filter element,
with its second end part directed to the second axial end of the filter housing, axially into the
housing and for allowing the protrusion to be withdrawn from the opening when removing the
filter element axially out of the housing.
The opening of the filter element is, viewed from the mouth, undercut. The opening
has a sloping side wall face which slopes with respect to the axial direction. The slope of the
sloping side wall face of the opening in the filter element is such that, when the protrusion of
the filter housing has been received in the opening and is withdrawn axially from the opening,
the sloping side wall face guides the protrusion out of the mouth. When the protrusion is
withdrawn axially and is engaged by the sloping side wall face, the protrusion and opening
will slightly rotate with respect to each other.
In an embodiment of the filter element provided with the opening, the slope of the
sloping side wall face is in the range of 20° - 40° with respect to the axial direction of the
filter element.
In an embodiment of the filter element provided with the opening, the mouth is
provided in a ring shaped wall, wherein, viewed in tangential direction, the mouth has a first
side where the sloping side wall face is provided and an opposing second side; and wherein
the ring shaped wall is provided with an axial projection, the axial projection being arranged
adjacent the mouth at the second side of the entry mouth.
For example, the ring shaped wall has an axially facing front face, which is shaped
with a pitch angle, the pitch angle being preferably at most 10°.
In an embodiment of the filter element provided with the opening, the projection has a
guide surface for guiding the protrusion over the projection when the protrusion runs over
the projection from its side opposing the side adjacent the mouth towards the mouth .
In an embodiment of the filter element, the second end part of the filter element is
provided with a sealing ring, such as an O-ring, having a ring axis perpendicular to a sealing
ring plane defined by the sealing ring, wherein the ring axis and the longitudinal axis of the
filter element extend at an acute angle with respect to each other, preferably in the range of
4-15°.
The invention further relates to a method of removing a filter element from a filter
assembly comprising a head, a filter housing which can be removably connected to the head,
and a filter element received in the filter housing;
wherein the filter housing comprises a first axial end and a second axial end, wherein the first
axial end is provided with a first rotational connector part;
wherein the head comprises a second rotational connector part which can be removably
engaged by the first rotational connector parts; wherein the housing can be connected to and
detached from the head by mutual rotation in a first direction of rotation respectively a second
direction of rotation opposite to the first direction of rotation;
wherein the filter element comprises:
o a tubular wall provided with a filtration medium;
o a first end part provided at a first axial end of the filter element; and
o a second end part provided at a second axial end of the filter element;
wherein the second end part of the filter element and the second axial end of the tubular
housing are provided with a locking assembly; comprising:
o an opening provided at one of either the filter element or the tubular housing ; and
o a protrusion provided at the other one of either the filter element or the filter
housing which is adapted to project in the opening;
wherein the opening comprises a mouth which opens in axial direction, which mouth is,
viewed in tangential direction, wider than, viewed in tangential direction, the protrusion;
wherein the opening comprises a sloping side wall face which slopes with respect to the axial
direction, which sloping side wall face, viewed in axial direction from the mouth into the
opening, widens said opening;
wherein the method starts from a condition in which:
o the filter housing is connected to head and
o the filter element has been received in the tubular housing with the protrusion
projecting in the opening;
wherein the method comprises:
• detaching the filter housing from the head by rotating the housing with respect to the
head in the second direction of rotation, in which the filter element is drawn tight
towards the second axial end of the filter housing by engagement of the sloping side
wall face of the opening, on the one hand, with the protrusion, on the other hand;
• removing the filter housing together with the filter element received in the filter
housing from the head;
removing the filter element from the housing in axial direction, which removing comprises
withdrawing the protrusion axially from the opening through the mouth wherein the sloping
side wall face guides the protrusion in the second direction of rotation out of the mouth.
The invention further relates also to a method of replacing, in a filter assembly
comprising a head, a filter housing which can be removably connected to the head, and a
filter element which has been received in the filter housing, the filter element by a further
filter element,
• the filter housing comprising a first axial end and a second axial end, wherein the first
axial end is provided with a first rotational connector part;
• the head comprising a second rotational connector part which can be removably
engaged by the first rotational connector parts; wherein the housing can be connected
to and detached from the head by mutual rotation in a first direction of rotation
respectively a second direction of rotation opposite to the first direction of rotation;
• the filter elements each comprising:
o a tubular wall provided with a filtration medium;
o a first end part provided at a first axial end of the filter element; and
o a second end part provided at a second axial end of the filter element;
wherein the second end part of each filter element and the second axial end of the tubular
housing are provided with a locking assembly; comprising:
• an opening provided at one of either the filter element or the tubular housing; and
• a protrusion provided at the other one of either the filter element or the filter housing
which is adapted to project in the opening;
wherein the opening comprises a mouth which opens in axial direction, which mouth is,
viewed in tangential direction, wider than, viewed in tangential direction, the protrusion;
wherein the opening comprises a sloping side wall face which slopes with respect to the axial
direction, which sloping side wall face, viewed in axial direction from the mouth into the
opening, widens said opening;
wherein the method starts from a condition in which:
• the filter housing is connected to head and
• the filter element has been received in the tubular housing with the protrusion
projecting in the opening;
wherein the method comprises:
• detaching the filter housing from the head by rotating the housing with respect to the
head in the second direction of rotation, in which the filter element is drawn tight
towards the second axial end of the filter housing by tangential engagement of the
sloping side wall face of the opening, on the one hand, with the protrusion, on the
other hand;
• removing the filter housing together with the filter element received in the filter
housing from the head;
• removing the filter element from the housing in axial direction, which removing
comprises withdrawing the protrusion axially from the opening through the mouth
wherein the sloping side wall face guides the protrusion to the mouth in the second
direction of rotation;
• inserting the further filter element axially into the housing and connecting the filter
housing with inserted further filter element to the head by rotating the housing with
respect to the head in the first direction of rotation,
• axially aligning the protrusion with the mouth followed by axially entering the
protrusion into the opening through the mouth.
When withdrawing the protrusion axially from the opening, the protrusion can be
guided to the mouth by the sloping side wall face of the opening.
It is possible that the protrusion is axially aligning with the mouth by rotating the
further filter element with respect to the filter housing in the first or second direction of
rotation. When the filter housing with accommodated further filter element is attached to the
head, the protrusion can be axially aligned with the mouth and axially entered into the
opening through the mouth. The filter element is positioned and locked with respect to the
filter housing automatically when installing the filter housing to the head.
The invention will now be described, by way of example only, with reference to the
figures.
Figure 1 is a cross section illustrating a first embodiment of a filter assembly
according to the invention.
Figure 2 is an exploded view of a lower axial end of the filter assembly shown in figure
1.
Figure 3 is a schematic view illustrating the inclination of the sealing ring.
Figure 4 is a perspective view illustrating a second embodiment of a filter assembly
according to the invention.
Figure 5 is a view showing as a detail view the housing part and filter element part of
the locking assembly of the embodiment of figure 4 in disconnected state. Fig 5a is a
perspective downward view and figure 5b is a perspective upward view.
Figure 6 shows, in side view, the same as figure 5, however now in connected state.
The filter assembly shown in figure 1 comprises a head 19, a filter housing 15 which
can be removably connected to the head 19, and a filter element 11 which can be received in
the filter housing 15.
The filter element 11 comprises a tubular wall 12 which is made of a filtration medium.
For example, the fitter medium is corrugated filter paper, nonwoven cloth or the like formed
into a cylinder, pleated filter paper, non-woven glass fibre or stainless steel wiremesh. The
filter element 11 has a first end part or upper end part 13 provided at a first axial end or upper
axial end of the filter element 11 and a second end part or lower end part 14 provided at a
second axial end or lower axial end 30 of the filter element 11. The filter element 11 has a
longitudinal axis 34 which extends in an axial direction of the filter element 11.
The filter housing 15 also comprises a first axial end or upper axial end 16 and a
second axial end or lower axial end 18. The upper axial end 16 is provided with a first
rotational connector part 17. The head 19 comprises a second rotational connector part 20
which can be removably engaged by the first rotational connector part 17. In this exemplary
embodiment, the rotational connector parts 17,20 are designed as threads. The housing 15
can be connected to the head 19 by rotating the housing 15 with respect to the head 19 in a
first direction (A) of rotation until the threads 17,20 are screwed home. The housing 15 can
be detached from the head 19 by rotating the housing 15 with respect to the head 19 in a
second, opposite direction (B) of rotation.
The filter housing 15 further comprises a core element 32, which is preferably
attached to the filter housing 15 at its lower axial end 18, so that the core element 32 is
removed from the head 19 together with the housing 15. As the core element 32 is attached
to the housing 15, it is further prevented that the core element might stay inside the filter
element and erroneously be disposed of together with the filter element. The core element
serves to protect the filter element against radial inward compression as a result from
external pressure exerted by the fluid to be filtered. In order to allow fluid to pass through the
wall of the core element, the core element is in general perforated all over its wall. The core
element can be attached to the housing in many different manners. For example the core
element 32 could be welded directly to the bottom of the housing 15 at the lower end 18.
Another way of attaching the core element to the housing at the lower end 18 is by use of a
leaf spring 53 as is explained detailed in PCT /NL2009/000137 of 22 June 2009 in the name
of the same applicant.
The filter element 11 can be accommodated axially into the filter housing 15 with its
lower end part 14 into the lower axial end 18 of the filter housing 15. The lower end part 14 of
the filter element 11 and the lower axial end 18 of the filter housing 15 are provided with a
locking assembly 50, 51. In this exemplary embodiment, the housing part 51 of the locking
assembly includes a ring shaped wall 26 which is attached to the filter housing 15, and an
opening 21 which is provided in the ring shaped wall 26. The ring shaped wall 26 has a front
face 40 facing axially., The filter element part 50 of the locking assembly carries a protrusion
22 which is arranged at the filter element 11 (see figure 2).
The opening 21 comprises a mouth 23 which opens in axial direction, upwards in the
embodiment shown in figures 1 and 2. The mouth 23 is, viewed in tangential direction, wider
than, viewed in tangential direction, the protrusion 22 for allowing the protrusion 22 to enter
into and out of the opening 21. The opening 21 is undercut viewed from the mouth 23 into
the opening 21. Viewed in tangential direction, the opening 21 has a first side 27 and an
opposing second side 28. The second side of the opening 28 extends essentially in axial
direction.
A sloping side wall face 24 is provided at the first side 27. The sloping side wall face
24 slopes with respect to the axial direction. In this exemplary embodiment, the slope a is in
the range of 20° -40° - in the shown embodiments about 30° - with respect to the axial
direction. Viewed from the lower axial end 18 to the upper axial end 16 of the filter housing,
the sloping side wall face 24 slopes in the second direction (B) of rotation.
The side of the protrusion 22 facing the sloping side wall face 24 of the opening 21 is
provided with a sloping protrusion face 25 having a slope a which corresponds to the slope a
of the sloping side wall face 24. When the protrusion 22 has been received in the opening 21
and the protrusion 22 is withdrawn axially from the opening 21, the sloping side wall face 24
guides the protrusion 22 to the mouth 23 while the protrusion 22 slightly rotates in the
second direction (B) of rotation.
The ring shaped wall 26 has an axially facing front face, which is shaped with a pitch
angle. For example, the pitch angle is approximately 10°. In addition, the ring shaped wall 26
is provided with an axial projection 29 which is arranged adjacent to the mouth 23 at the
second side 28 of the mouth 23. The projection 29 has a guide surface 31 for guiding the
protrusion 22 over the projection 29 when the protrusion 22 is moved over the projection 29
in the first direction (A) of rotation, i.e. towards the mouth 23.
The lower end part 14 of the filter element 11 is provided with a sealing ring 33, such
as an O-ring. The sealing ring has a ring axis 35 which runs perpendicular to a sealing ring
plane defined by the sealing ring 33. The ring axis 35 and the longitudinal axis 34 of the filter
element 11 extend at an acute angle (B) with respect to each other. For example, the acute
angle is in the range of 4-15° (see figure 3). The filter housing 15 is provided at its lower axial
end 18 with a sealing seat 36 which is adapted to the sealing ring 33 for sealing the interior
37 of the filter element 11 with respect to the lower axial end 18 of the filter housing 15.
When the protrusion 22 has been axially aligned with the mouth 23 and positioned
outside the opening 21 directly adjacent the mouth 23, the sealing ring 33 is at a distance
from the sealing seat 36. The sealing seat 36 faces radially and adjoins a ring shaped front
face 39 facing axially towards the upper axial end 16 of the housing 15. The front face 39
defines a front face plane. When the protrusion 22 has been received in the opening 21, the
front face plane is parallel to the sealing ring plane and the sealing ring 33 seals against the
sealing seat 36 such that a circumferential seal is provided which seals along the entire
sealing ring 33.
Figure 4 shows a second embodiment of the filter assembly according to the
invention. This second embodiment substantially corresponds to the first embodiment
described with reference to figures 1-3. Therefore, the same or similar components are
designated by the same reference numerals.
The embodiment shown in figure 4 differs from the embodiment shown in figures 1-3
by the fact that the filter element 11 is provided with the opening 21 and the filter housing 15
is provided with the protrusion 22. As a result, the mouth 23 opens into the direction of the
lower axial end 18 of the filter housing 15, and the sloping side wall face 24, viewed from the
first axial end 16 to the second axial end 18, slopes in the first direction (A) of rotation.
Leaf springs, like 53 in figure 2, extending through apertures 53 41 serve to attach
the housing part 51 to the filter housing 15. In the embodiment according to figures 1-3, the
housing part 51 is provided with the opening 21 and in the embodiment according to figures
4-5 the housing part 51 is provided with the protrusion 22. As will be clear, the housing part
51 can according to the invention be attached to the filter housing 15 in many different
manners, like gluing, welding. It is according to the invention also conceivable that the
housing part 51 is an integral part of the filter housing 15 or that the opening 21 or protrusion
20 is formed directly in or with the housing.
Further referring to the embodiment of figures 4-6, the undercut opening 21 is in fact
formed in a flange 54, which is on its upper side provided with a rib 55 defining the sloping
side wall face 24 and the first side 27 of the opening 21 as well as with a rib 56 defining the
second side 28 of the opening with an essentially axial face. The opening 21 has a mouth 23
at the lower side of the opening. Further the undercut opening 21 is in this embodiment also
open at the upper side opposite the mouth 23.
Further, in figure 5b one can see the sealing 33 having a ring axis 35 which extends -
see figure 3 - at an acute angle β with respect to the longitudinal axis 34 of the filter element
12 (so called slanting arrangement); and in figure 5a one can see the sealing seat 36 with
ring face 39, wherein the ring face 39 defines a plane having a perpendicular axis extending
at an acute angle β with respect to the longitudinal axis 34 of the filter element. In the
embodiment of figure 5b the sealing ring 33 is ribbon shaped with - in axial direction - a
width of about 3-5 mm. It is note that in figure 5b the indication lines of reference number 33
end at the lower edge of the ribbon shaped sealing ring 33, and that due to the slanting
arrangement of the sealing ring the upper edge of the ribbon shaped sealing ring is visible on
the right side of figure 5b but not visible on the left side of figure 5b.
The invention is not limited to the embodiments shown in the figures. The skilled
person can make various modifications without leaving the scope of the invention.
It should be noted that the inclined sealing ring has independent significance and
could be the subject of a divisional application. This aspect can be described as follows:
A filter assembly, comprising a head, a filter housing which can be removably
connected to the head, and a filter element which can be received in the filter housing, the
filter element comprising a tubular wall provided with a filtration medium, a longitudinal axis, a
first end part provided at a first axial end of the filter element, and a second end part provided
at a second axial end of the filter element, the filter housing comprising a first axial end and a
second axial end, the second end part of the filter element being provided with a sealing ring,
such as an O-ring, having a ring axis perpendicular to a sealing ring plane defined by the
sealing ring, wherein the ring axis and the longitudinal axis of the filter element extend at an
acute angle with respect to each other, preferably in the range of 4-15°, and wherein the filter
housing is provided at its second axial end with a sealing seat which is adapted to the sealing
ring of the filter element. Thus, the interior of the filter element can be sealed with respect to
the second axial end of the filter housing. A filter assembly of this type can be provided with
one or more of the features of the dependent claims.
In addition, the aspect of the inclined sealing ring relates to the following:
A filter element comprising a tubular wall provided with a filtration medium, a longitudinal axis,
a first end part provided at a first axial end of the filter element; and a second end part
provided at a second axial end of the filter element, the second end part of the filter element
being provided with a sealing ring, such as an O-ring, having a ring axis perpendicular to a
sealing ring plane defined by the sealing ring, wherein the ring axis and the longitudinal axis
of the filter element extend at an acute angle β with respect to each other, preferably in the
range of 4-15°. A filter element of this type can be provided with one or more of the features
of the dependent claims.
Claims
1] A filter assembly (10), comprising a head (19), a filter housing (15) which can be
removably connected to the head (19), and a filter element (11) which can be received in the
filter housing (15),
• the filter element (11) comprising:
o a tubular wall (12) provided with a filtration medium;
o a first end part (13) provided at a first axial end of the filter element (11); and
o a second end part (14) provided at a second axial end (30) of the filter element
(11);
• the filter housing (15) comprising a first axial end (16) and a second axial end (18),
wherein the first axial end (16) is provided with a first rotational connector part (17);
• the head (19) comprising a second rotational connector part (20) which can be removably
engaged by the first rotational connector part (17),
wherein the housing (15) can be connected to the head (19) by rotating the housing (15) with
respect to the head (19) in a first direction (A) of rotation and wherein the housing (15) can
be detached from the head (19) by rotating the housing (15) with respect to the head (19) in
a second direction (B) of rotation, the second direction (B) of rotation being opposite to the
first direction (A) of rotation;
wherein the second end part (14) of the filter element (11) and the second axial end (18) of
the filter housing (15) are provided with a locking assembly comprising:
• an opening (21) provided at one of either the filter element (11) or the filter housing
(15); and
• a protrusion (22) provided at the other one of either the filter element (11) or the filter
housing (15) which is adapted to project in the opening (21);
wherein the opening (21) comprises a mouth (23) which opens in axial direction, which
mouth (23) is, viewed in tangential direction, wider than, viewed in tangential direction, the
protrusion (22) for allowing the protrusion (22) to enter into the opening (21) when inserting
the filter element (11), with its second end part (14) directed to the second axial end (18) of
the filter housing (15), axially into the housing (15) and for allowing the protrusion (22) to be
withdrawn from the opening (21) when removing the filter element (11) axially out of the
housing (15);
wherein the opening (21) comprises a sloping side wall face (24) sloping with respect to the
axial direction, which sloping side wall face (24), viewed in axial direction from the mouth
(23) into the opening (21), widens said opening (21) such that, when the protrusion (22) has
been received in the opening (21) and is withdrawn axially from the opening (21), the sloping
side wall face (24) guides the protrusion (22) in the second direction (B) of rotation out of the
mouth (23).
2] Filter assembly (10) according to claim 1, wherein the side of the protrusion (22)
facing the sloping side wall face (24) of the opening (21) is provided with a sloping protrusion
face (25) having a slope (a) which corresponds to the slope (a) of the sloping side wall face
(24).
3] Filter assembly (10) according to one of the preceding claims, wherein the slope (a) of
the side wall face (24) is in the range of 20° - 40° with respect to the axial direction.
4] Filter assembly (10) according to one of claims 1-3, wherein the filter element (11) is
provided with the protrusion (22) and wherein the filter housing (15) is provided with the
opening (21), wherein the mouth (23) opens into the direction of the first axial end (16) of the
filter housing (15), and wherein the sloping side wall face (24), viewed from the second axial
end (18) to the first axial end (16), slopes in the second direction (B) of rotation such that,
when the filter housing is being removed from the head by rotating the housing.with respect
to the head in the second direction (B) of rotation, the filter element is drawn tight towards
the second axial end (18) of the filter housing (15) by engagement of the sloping side wall
face (24) of the opening (21) with the protrusion (22).
5] Filter assembly (10) according to one of claims 1-3, wherein the filter element (11) is
provided with the opening (21) and wherein the filter housing (15) is provided with the
protrusion (22), and wherein the mouth (23) opens into the direction of the second axial end
(18) of the filter housing (15), and wherein the sloping side wall face (24), viewed from the
first axial end (16) to the second axial end (18), slopes in the first direction (A) of rotation
such that, when the filter housing is being removed from the head by rotating the housing
with respect to the head in the second direction (B) of rotation, the filter element is drawn
tight towards the second axial end (18) of the filter housing (15) by engagement of the
sloping side wall face (24) of the opening (21) with the protrusion (22).
6] Filter assembly (1.0) according to one of claims 1-5,
wherein the opening (21) is provided in a ring shaped wall (26);
wherein, viewed in tangential direction, the mouth (23) has a first side (27) where the sloping
. side wall face (24) is provided and an opposing second side (28); and
wherein the ring shaped wall (26) is provided with an axial projection (29), the axial projection
(29) being arranged adjacent the mouth (23) at the second side (28) of the mouth (23).
7] Filter assembly (10) according to claim 6, wherein the ring shaped wall (26) has an
axially facing front face (40), which is shaped with a pitch angle, the pitch angle being
preferably at most 10°.
8] Filter assembly (10) according to claim 6 or 7, wherein the projection (29) has a guide
surface (31) for guiding the protrusion (22) over the projection (29) when the protrusion (22)
runs over the projection (29) from its side opposing the side adjacent the mouth (23) towards
the mouth (23).
9] Filter assembly according to one of the preceding claims, wherein the second end
part (14) of the filter element (11) is provided with a sealing ring (33), such as an O-ring,
having a ring axis (35) perpendicular to a sealing ring plane defined by the sealing ring (33),
wherein the ring axis (35) and the longitudinal axis (34) of the filter element (11) extend at an
acute angle (β) with respect to each other, preferably in the range of 4-15°, and wherein the
filter housing (15) is provided at its second axial end (18) with a sealing seat (36) which is
adapted to the sealing ring (33) for sealing the interior (37) of the filter element (11) with
respect to the second axial end (18) of the filter housing (15).
10] Filter assembly according to claim 9, wherein the sealing seat (36) faces radially;
wherein a ring face (39) facing axially towards the first axial end (16) adjoins the sealing seat
(39); wherein the ring face (39) defines a ring face plane; and wherein, when the protrusion
(22) has been received in the opening (21), the ring face plane is parallel to the sealing ring
plane.
11] Filter assembly according to claim 10, wherein, when the protrusion (22) has been
axially aligned with the mouth (23) and positioned outside the opening (21) directly adjacent
the mouth (23), the sealing ring (33) is at a distance from the sealing seat (36).
12] Filter assembly according to one of the preceding claims, wherein, when the
protrusion has been received in the opening, the protrusion is movable between a position in
which the protrusion is aligned with the mouth of the opening and a position in which the
protrusion, viewed in axial direction, overlaps at least partially with the sloping side wall face.
13] A filter element (11) comprising:
o a tubular wall (12) provided with a filtration medium;
o a first end part (13) provided at a first axial end of the filter element (11); and
o a second end part (14) provided at a second axial end (30) of the filter element (11);
wherein the second end part (14) of the filter element (11) is provided with a protrusion (22),
and wherein a side of the protrusion (22) is provided with a sloping protrusion face (25) which
slopes at a slope (a) with respect to the axial direction of the filter element.
14] Filter element (11) according to claim 12, wherein, viewed in axial direction from the
second end part (14) of the filter element (11) to the first end part (13) of the filter element
(11), the sloping protrusion face (25) is arranged at that side of the protrusion (22) which
faces, with respect to the longitudinal axis (34) of the filter element (11), in clock-wise
direction (A).
15] A filter element (11) comprising:
o a tubular wall (12) provided with a filtration medium;
o a first end part (13) provided at a first axial end of the filter element (11); and
o a second end part (14) provided at a second axial end (30) of the filter element (11);
wherein the second end part (14) of the filter element (11) is provided with an opening (21)
which comprises a mouth (23) which opens in axial direction, and wherein the opening (21)
comprises a sloping side wall face (24) which slopes at a slope (a) with respect to the axial
direction of the filter element, and wherein the sloping side wall face (24), viewed in axial.
direction from the mouth (23) into the opening (21), widens said opening (24).
16] Filter element (11) according to claim 15, wherein, viewed in axial direction from the
second end part (14) of the filter element (11) to the first end part (13) of the filter element
(11), the sloping side wall face (24) is arranged at that side of the opening (21) which faces,
with respect to the longitudinal axis (34) of the filter element (11), in clock-wise direction (A).
17] Filter element (11) according to one of claims 13-16, wherein the filter element (11)
is adapted to be received in a filter housing (15) of a filter assembly according to one of
claims 1-12.
18] Filter element (11) according to one of claims 13-17, wherein the said slope (a) is in
the range of 20° - 40° with respect to the axial direction of the filter element (11).
19] Filter element (11) according to one of claims 13-18,
wherein the opening (21) is provided in a ring shaped wall (26);
wherein, viewed in tangential direction, the mouth (23) has a first side (27) where the sloping
side wall face (24) is provided and an opposing second side (28); and
wherein the ring shaped wall (26) is provided with an axial projection (29), the axial projection
(29) being arranged adjacent the mouth (23) at the second side (28) of the entry mouth (23).
20] Filter element (11) according to claim 19, wherein the ring shaped wall (26) has an
axially facing front face (40), which is shaped with a pitch angle, the pitch angle being
preferably at most 10°.
21 ] Filter element (11) according to claim 19 or 20, wherein the projection (29) has a
guide surface (31) for guiding the protrusion (22) over the projection (29) when the protrusion
(22) runs over the projection (29) from its side opposing the side adjacent the mouth (23)
towards the mouth (23).
22] Filter element (11) according to one of the claims 13-21, wherein the second end part
(14) of the filter element (11) is provided with a sealing ring (33), such as an O-ring, having a
ring axis (35) perpendicular to a sealing ring plane defined by the sealing ring (33), wherein
the ring axis (35) and the longitudinal axis (34) of the filter element (11) extend at an acute
angle (β) with respect to each other, preferably in the range of 4-15°.
23] Method of removing a filter element (11) from a filter assembly comprising a head
(19), a filter housing (15) which can be removably connected to the head (19), and a filter
element (11) received in the filter housing (15);
wherein the filter housing (15) comprises a first axial end (16) and a second axial end (18),
wherein the first axial end (16) is provided with a first rotational connector part (17);
wherein the head (19) comprises a second rotational connector part (20) which can be
removably engaged by the first rotational connector parts (17, 20); wherein the housing (15)
can be connected to and detached from the head (19) by mutual rotation in a first direction
(A) of rotation respectively a second direction (B) of rotation opposite to the first direction (A)
of rotation;
wherein the filter element comprises:
o a tubular wall (12) provided with a filtration medium;
o a first end part (13) provided at a first axial end of the filter element (11); and
o a second end part (14) provided at a second axialend (30) of the filter element
(11);
wherein the second end part (14) of the filter element (11) and the second axial end (18) of
the tubular housing (15) are provided with a locking assembly; comprising:
o an opening (21) provided at one of either the filter element (11) or the tubular
housing (15); and
o a protrusion (22) provided at the other one of either the filter element (11) or the
filter housing (15) which is adapted to project in the opening (21);
wherein the opening (21) comprises a mouth (23) which opens in axial direction, which mouth
(23) is, viewed in tangential direction, wider than, viewed in tangential direction, the
protrusion (22);
wherein the opening (21) comprises a sloping side wall face (24) which slopes with respect to
the axial direction, which sloping side wall face (24), viewed in axial direction from the mouth
(23) into the opening (21), widens said opening (21);
wherein the method starts from a condition in which:
o the filter housing is connected to head (19) and
o the filter element (11) has been received in the tubular housing (15) with the
protrusion (22) projecting in the opening (21);
wherein the method comprises:
• detaching the filter housing (15) from the head (19) by rotating the housing (15) with
respect to the head (19) in the second direction (B) of rotation, in which the filter
element (11) is drawn tight towards the second axial end (18) of the filter housing (10)
by engagement of the sloping side wall face (24) of the opening (21), on the one
hand, with the protrusion (22), on the other hand;
• removing the filter housing (15) together with the filter element (11) received in the
filter housing (15) from the head (19);
• removing the filter element (11) from the housing (15) in axial direction, which
removing comprises withdrawing the protrusion (22) axially from the opening (21)
through the mouth (23) wherein the sloping side wall face (24) guides the protrusion
(22) in the second direction (B) of rotation out of the mouth (23).
24] Method of replacing, in a filter assembly comprising a head (19), a filter housing (15)
which can be removably connected to the head (19), and a filter element (11) received in the
filter housing (15), the filter element (11) by a further filter element (11),
wherein the filter housing (15) comprises a first axial end (16) and a second axial end (18),
wherein the first axial end (16) is provided with a first rotational connector part (17);
wherein the head (19) comprises a second rotational connector part (20) which can be
removably engaged by the first rotational connector parts (17, 20); wherein the housing (15)
can be connected to and detached from the head (19) by mutual rotation in a first direction
(A) of rotation respectively a second direction (B) of rotation opposite to the first direction (A)
of rotation;
wherein the filter elements each comprise:
o a tubular wall (12) provided with a filtration medium;
o a first end part (13) provided at a first axial end of the filter element (11); and
o a second end part (14) provided at a second axial end (30) of the filter element
(11);
wherein the second end part (14) of each filter element (11) and the second axial end (18) of
the tubular housing (15) are provided with a locking assembly; comprising:
o an opening (21) provided at one of either the filter element (11) or the tubular
housing (15); and
o a protrusion (22) provided at the other one of either the filter element (11) or the
filter housing (15) which is adapted to project in the opening (21);
wherein the opening (21) comprises a mouth (23) which opens in axial direction, which mouth
(23) is, viewed in tangential direction, wider than, viewed in tangential direction, the
protrusion (22);
wherein the opening (21) comprises a sloping side wall face (24) which slopes with respect to
the axial direction, which sloping side wall face (24), viewed in axial direction from the mouth
(23) into the opening (21), widens said opening (21);
wherein the method starts from a condition in which:
o the filter housing is connected to head (19) and
o the filter element (11) has been received in the tubular housing (15) with the
protrusion (22) projecting in the opening (21);
wherein the method comprises:
• detaching the filter housing (15) from the head (19) by rotating the housing (15) with
respect to the head (19) in the second direction (B) of rotation, in which the filter
element (11) is drawn tight towards the second axial end (18) of the filter housing (10)
by engagement of the sloping side wall face (24) of the opening (21), on the one
hand, with the protrusion (22), on the other hand;
• removing the filter housing (15) together with the filter element (11) received in the
filter housing (15) from the head (19);
• removing the filter element (11) from the housing (15) in axial direction, which
removing comprises withdrawing the protrusion (22) axially from the opening (21)
through the mouth (23) wherein the sloping side wall face (24) guides the protrusion
(22) in the second direction (B) of rotation out of the mouth (23);
• inserting the further filter element (11) axially into the housing (15) and connecting the
filter housing (15) with inserted further filter element (11) to the head (19) by rotating
the housing (15) with respect to the head (19) in the first direction (A) of rotation,
• axially aligning the protrusion (22) with the mouth (23) followed by axially entering the
protrusion (22) into the opening (21) through the mouth (23).
25] Method according to claim 24, wherein axially aligning the protrusion (22) with the
mouth (23) comprises rotating the further filter element (11) with respect to the filter housing
(15)'.
26] Method according to claim 25, wherein axially aligning the protrusion (22) with the
mouth (23) and axially entering the protrusion (22) into the opening (21) through the entry
mouth (23) take place during attaching the tubular housing (15) with inserted second filter
element to the head (19).
The invention relates to a filter assembly,
comprising a head, a filter housing which can be connected
to the head, and a filter element which can be received in
the filter housing. The invention further relates to a filter
element and a method of replacing a filter element. The filter element
comprises a tabular wall provided with a filtration
medium; a first end part provided at a first axial end of
the filter element; and a second end part provided at a second
axial end of the filter element, The second end part of
the filter element is provided with a either a protrusion or
an undercut opening, on tie one hand, and the second end
of the housing is provided with either an undercut opening
or a protrusion, on the other hand. A side of the protrusion
or opening is provided with a sloping face which slopes at
a slope with respect to the axial direction of the filter element.
