HYDRAULIC MOTOR INTEGRATED IN A VEHICULAR WHEEL
Application field of the invention
The present invention refers to the field of hydraulic
motors directly integrated in vehicular wheels and more
precisely to a radial piston hydraulic motor.
Description of the prior art
Hydraulic motors are often used on earthworks machines.
Recently, such motors have been used also in commercial
vehicles, for assisting the thermal engine in particular
conditions where a high pickup torque is required.
Radial hydraulic engines are characterized in that they
have a plurality of piston arranged and movable radially on
a circular crown in order to press on a shaped profile
which provokes its rotation. Such profile is made on the
internal surface of a ring, so called shaped ring, which is
integral with the wheel.
Several hydraulic motors directly inserted in the wheel hub
are known in the art. They are subject to several problems.
Firstly, the fixed part of the oil distributor that is
necessary to actuate the radial pistons is usually mounted
overhead of the end of the articulated stub axle, namely in
a coaxial way with respect to the articulated stub axle.
This implies that it projects from the hub profile and thus
it is more subject to hit sidewalks and other objects.
Another problem is to confine the hydraulic oil in another
portion of the hub.
According to the devices known in the art, the most
external bearing, with respect to the free end of the
articulated stub axle, placed between the articulated stub
axle and the hub, is within the area of the hub that
confines the hydraulic oil. Thus, such bearing, instead of
working in lubricating grease or oil, has to work in the
hydraulic oil, whose physical-chemical characteristics are
clearly different from the lubricating grease or oil.
A further problems of the known schemes relates to the fact
that distinct fixing means are provided to connect the hub
to the articulated stub axle and to connect the hydraulic
motor to the articulated stub axle.
Summary of the invention
Therefore the aim of the present invention is to overcome
all the aforementioned drawbacks and to provide a hydraulic
motor integrated in a vehicular wheel.
According to a first aspect of the present invention, the
distributor has an annular form and is splined on the
articulated articulated stub axle so that it is within the
hub. A first advantage consists in that the distributor is
inside the hub, and it does not project from it.
According to a further aspect of the present invention, the
fixed part of the distributor has an external lateral
surface that is tapered towards the free end of the
articulated articulated stub axle and the movable part of
the distributor has also an annular form with an internal
lateral surface complementary to the external lateral
surface of the respective fixed part, so that the movable
part is splined to the fixed part of the distributor and
not to the articulated stub axle. In other words, the
movable part of the distributor is fully supported by the
fixed part of the distributor.
This, advantageously, allows to limit the axial encumbrance
of the distributor. Moreover, it allows to release on the
fixed part of the distributor the axial forces induced on
the mobile part of the distributor, thus avoiding to have
to support the distributor with cup bearings.
According to a further aspect of the present invention, the
fixed part of the distributor splined to the articulated
stub axle defines an annular housing for housing an annular
gasket for confining the hydraulic oil.
According to a further aspect of the present invention, the
connection of both the hub and the hydraulic motor to the
articulated stub axle is made by means of a single shared
connection, namely by means of a threaded ring nut on the
free end of the stub axle.
According to a further aspect of the present invention, the
adjustment of the position of the bearings placed between
the hub and the articulated stub axle is made by a single
connection means and preferably also by means of a beat
interface between the fixed part of the distributor and the
articulated stub axle.
The object of the present invention is a hydraulic motor
integrated in a vehicular wheel, in accordance with claim
1.
A ground vehicle comprising the aforementioned hydraulic
motor integrated in at least a vehicular wheel is also
object of the present invention.
The claims are an integral part of the present description.
Brief description of the Figures
The purposes and advantages of this invention will become
more clear from the following detailed description of an
embodiment thereof (and of its alternative embodiments) and
from the drawings that are attached hereto that are merely
illustrative and not limitative, in which in figure 1 shows
an axial view with respect to the articulated stub axle of
a preferred embodiment of the hydraulic motor according to
the present invention.
Figure 2 shows an enlarged view of figure 1 .
In the figures the same reference numbers and letters
identify the same elements or components.
Detailed description of preferred embodiments of the
invention
Figure 1 shows a view according to an axial section with
respect to the articulated stub axle 100 of the hydraulic
motor 1 according to the present invention. The articulated
stub axle, indeed, defines the development axis X of the
hydraulic motor 1 .
It is evident that most of the components of the motor are
contained in the hub.
Although the free end 101 of the articulated stub axle 100
represents the most external part of the hydraulic motor 1 ,
it is completely contained within the wheel, considering
the stop surface 201 of the hub 200, to which the tire rim,
not shown, is connected.
The hub's shape has a cylindrical symmetry. Preferably it
has a cylindrical shape in the proximity of the
articulation 102 of the articulated stub axle 100 and it
tends to widen like a bell towards the free end 101, namely
rightwards, looking at figure 1 .
The motor body 12 is a torus integrating a plurality of
radial pistons, not shown, acting on the shaped ring 13.
While the motor body is rotatably integral with the
articulated stub axle 100, the shaped ring 13 is integral
with the hub 200.
The hydraulic oil distributor comprises a rotatably fixed
part 16 and a rotating part 15 with respect to the
articulated stub axle. For more convenience, in the
following they will be indicated as fixed part and movable
part, respectively.
Both the fixed and the movable part can move axially.
The fixed part 16 has an annular shape with an external
surface tapered towards the free end 101 of the articulated
stub axle and is splined to the articulated stub axle. The
movable part 15 of the distributor has an annular shape as
well with a preferably cylindrical external surface and an
internal surface complementary to the external surface of
the fixed part. Thus the movable part 15 of the distributor
fits on the fixed part 16 being annular with respect to it.
This is enough to determine, due to the passage of the
hydraulic oil in the interface between the two parts, an
axial thrust that spread the two parts apart.
According to a further alternative embodiment of the
present invention, the axial forces acting on the movable
part of the distributor are balanced, since, during the
passage of the hydraulic oil, reaction forces develop which
tend to move the movable part away from the motor body 12.
Opposite forces having equal or higher intensity are
generated by the oil at the interface between the fixed and
the movable part of the distributor, as shown above. Thus a
sort of hydraulic bearing is generated between the fixed
and movable part of the distributor. The fixed part of the
distributor is splined to the slab axle, so that it can
axially slide, thus it compresses the whole bearing pack
(18,19 and 20) . This solution allows to avoid providing a
bearing suitable to support a rotating element, since the
movable part 15 releases axial reaction forces on the fixed
part 16 of the distributor, which is rotatably fixed.
According to a preferred embodiment of the invention, in
order to increase the axial thrust spreading apart the
fixed part 16 and the rotating part 15 of the distributor,
chambers 1516 are provided on the interface between the two
parts. In particular, such chambers having a preferably
rectangular axial section, always ensure the oil passage in
the pipes 15.1 and 16.1.
The surface of the chambers 1516 may be appropriately
dimensioned in order to vary the aforementioned axial
thrust .
The pipes 16.1 of the fixed part may be radial with respect
to the axial symmetry of the motor. The pipes 15.1 made in
the movable part of the distributor, collect oil from the
pipes of the fixed part, to convey it, towards the right of
the figure, to the motor body 12. Thus they have a first
portion that is more markedly radial and a second portion
that is more markedly axial.
The movable part 15 of the distributor is made rotatably
integral with the shaped ring 13 and with the hub 200 by
means of a spline or of a key between the body 15 and the
hub .
The annular portion of the fixed part 16 of the distributor
comprises a seat for housing an annular gasket fitted
internally on the fixed part of the distributor and
externally on the hub 200. Having the gasket in such
position allows to confine the portion of hub reached by
the hydraulic oil, which, as it is known, is highly
corrosive .
Moving towards the left of the drawing, between the hub 200
and the stub axle 100, a first bearing 18 - also called
external bearing - and a second bearing 20 - also called
internal bearing - and a further annular gasket 21 are
housed in a sequence. All these elements fit internally on
the articulated stub axle and externally on the hub.
The reciprocal position between the bearings is defined by
a spacer 19, fitted on the articulated stub axle 100, and
possibly by the stop teeth 202 and 203 made in the internal
surface of the hub. Such stop teeth define the spacers
between the bearings. This means that an axial inwards
displacement, towards the left of the figure, of the
external bearing 18 induces the same translation of the
internal bearing 19 due to the reciprocal interference of
the hub 200 and of the spacer 19 obtaining the desired pre
load .
The fixed part 16 of the distributor is directly in contact
with the first bearing 18, thus the aforementioned axial
displacement of the first bearing can be determined by the
interaction with the fixed part 16 of the distributor.
Analogously, being the distributor 15-16 directly in
contact with the motor body 12, an axial displacement of
the distributor can be determined by the interaction with
the motor body 12. A single ring nut 11, threading on the
free end 101 of the articulated stub axle acting on the
motor body 12, thus acts on the distributor 15-16, on the
bearing 18, on the spacer 19 and hub 200, on the bearing
20 .
It is evident that by virtue of the solution shown herein,
a single connection element allows not only to assembly the
engine, but also to adjust the position of the bearings 18
and 20.
It is worth noting that the radial encumbrance is limited,
since no further connection element is provided except the
single ring nut 11.
It is also possible to notice that the fixed part 16 of the
distributor can axially slide on the articulated stub axle.
This means that it does not perform any stop function for
the components at its left, namely the bearings and the
respective spacer. Only the ring 11 performs this function.
The parts that are rotatably fixed with respect to the
articulated stub axle, such as for example, the motor body
12, or the fixed part 16 of the distributor, can be
equipped with a splined profile or with other means
blocking its rotation.
From the description set forth above it will be possible
for the person skilled in the art to embody the invention
with no need of describing further construction details.
The elements and the characteristics described in the
different preferred embodiments may be combined without
departing from the scope of the present application.

CLAIMS
1 . Hydraulic motor (1) integrated in a vehicular wheel
comprising
- a hub (200) having a cylindrical symmetry supported by an
articulated stub axle (100) and defining a development axis
(X) of the hub and of the hydraulic motor,
a motor body (12), rotatably integral with the
articulated stub axle (100), having an annular shape and
being equipped with radial pistons,
- a shaped ring (13) integral with a hub (200) and on which
radial pistons act,
- a hydraulic oil distributor (15-16),
wherein the hydraulic oil distributor (15-16) is housed in
the hub (100) .
2 . Motor according to claim 1 , wherein said oil distributor
has an overall annular shape and is suitable to be splined
to the articulated stub axle (100) .
3 . Motor according to claim 1 , wherein said distributor
comprises a first part (16), rotatably fixed, and a second
part (15), rotatably movable with respect to the
articulated stub axle (100), wherein said first part (16)
has an annular shape with an external surface tapered
towards a free end (101) of the articulated stub axle
(100) .
4 . Motor according to claim 3 , wherein said second part
(15) has an annular shape with an internal surface
complementary to the external surface of said first part,
so that it is splined to said first part (16) .
5 . Motor according to claim 4 , wherein first hydraulic oil
pipes (16.1) have a radial development and are made in the
first part of the distributor (16) and wherein second
hydraulic oil pipes (15.1) are made in the second part of
the distributor (15) with at least a portion having an
axial development.
6 . Motor according to claim 5 , wherein thrust chambers
(1516) are defined in correspondence of the complementary
surfaces of the two parts (15, 16) of the hydraulic oil
distributor (15 - 16) .
7 . Motor according to one of the previous claims, further
comprising a first (18) and a second bearing (20) placed
between the articulated stub axle (100) and the hub (200),
the bearings being spaced between each other by means of
spacers means (19, 202,203), wherein said first bearing
(18) is directly in contact with said hydraulic oil
distributor (15-16), so that an axial displacement of the
distributor causes an axial displacement of the bearings
(18, 20) .
8 . Motor according to claim 7 , wherein said first bearing
(18) is directly in contact with only said first part (15,
16) of the hydraulic oil distributor (15 - 16) .
9 . Motor according to one of the claims 7 or 8 , further
comprising a single ring nut (11) threading on the free end
(101) of the articulated stub axle (100) blocking in a
sequence: motor body (12), distributor (15-16), first
bearing (18), spacer (19), second bearing (20), so that
said single ring nut allows both to assemble the engine and
to adjust the position of said blocked components.
10. Motor according to one of the previous claims, wherein
said distributor (15-16) defines a seat for an annular
gasket (17) confining the hydraulic oil.
11. Motor according to claim 10, wherein said seat is
defined by the first part (16) of the distributor,
rotatably fixed with respect to the articulated stub axle
(100) .
12. Motor according to one of the previous claims from 6 to
9 , wherein said articulated stub axle comprises at least a
stop surface (103) for limiting the axial sliding of one of
the components (11, 12, 15-16) splined to it.
13. Ground vehicle a wheel wherein an hydraulic motor
according to any of the preceding claims is housed.