FORM 2
THE PATENT ACT 1970 (39 of 1970)
&
The Patents Rules, 2003 COMPLETE SPECIFICATION (See Section 10, and rule 13)
1. TITLE OF INVENTION STABILIZER FOR A UTILITY VEHICLE
2. APPLICANT(S)

a) Name : ZF FRIEDRICHSHAFEN AG
b) Nationality : GERMAN Company
c) Address : 88038 FRIEDRICHSHAFEN
GERMANY
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed : -

The invention relates to a stabiliser for a utility vehicle, comprising an elongate torsion spring and two link arms fixedly connected to the torsion spring and extending away from said torsion spring, between which the torsion spring extends.
US 4 648 620 discloses a stabiliser for a vehicle which comprises a torsion spring bar, at the ends thereof a bent-back arm being respectively arranged. In this case, the arms are connected via joints to a vehicle axle. The torsion spring bar extends through a torsion spring tube which is divided into two, the outer ends thereof being welded to the torsion spring bar. The two parts of the torsion spring tube may be releasably connected to one another by means of a coupling which may be actuated.
In many utility vehicles, for anti-roll stabilization, the driver's cab is connected in the front region to the vehicle chassis by a stabiliser. Said stabiliser consists of two connecting rods and/or levers and a torsion bar which is configured to be either round, tubular or as a profile, which connects the two connecting rods to one another fixedly in terms of rotation. The drawback with this system, however, is that the driving comfort is substantially impaired, in particular when driving on poor, uneven and windy stretches of road, caused by considerable rolling of the driver's cab in spite of the anti-roll stabilization. In order to improve the driving comfort, a development exists to prevent or minimise the rolling of the driver's cab, even in these situations, by installing an additional active component (actuator) in the stabiliser. The cab then remains in one plane relative to the road. Nevertheless, high bending moments and lateral forces which occur during the driving of the vehicle may lead to wear and thus to a significant reduction in the life of the actuator and/or to damage or destruction of the actuator, in particular if said actuator comprises a hydraulic oscillating motor.
Proceeding therefrom, the object of the invention is to develop a stabiliser of the aforementioned type such that the actuator is protected from damage as a result of bending moments. Preferably, the actuator is also intended to be protected from damage as a result of lateral forces.

This object is achieved according to the invention by a stabiliser according to Claim 1. Preferred developments of the invention are set forth in the sub-claims.
The stabiliser according to the invention for a utility vehicle, in particular a commercial vehicle, comprises an elongate torsion spring, two link arms fixedly connected to the torsion spring and extending away from said torsion spring, between which the torsion spring extends, and an actuator which is arranged in parallel with the torsion spring and which is connected to the torsion spring or the link arms by the interposition of hinge joints or leaf springs.
By the use of hinge joints or leaf springs, it is not possible for any bending moments or only very small bending moments which, for example, result from lateral forces occurring during cornering, to be transmitted to the actuator. On the other hand, rotational movements of the actuator may be transmitted by means of the hinge joints or leaf springs.
The use of leaf springs is suitable, in particular, in the case of relatively small pivot angles, so that the leaf springs may also be considered as a simplified and cost-effective design of joint.
The actuator is preferably connected on both sides to the torsion spring or the link arms by the interposition of the hinge joints or leaf springs. In particular, the actuator is connected to the link arms or the ends of the torsion spring by the interposition of the hinge joints or leaf springs.
The actuator forms, in particular, a rotary actuator or rotational actuator. Preferably, the actuator comprises two machine parts which may be rotated relative to one another, and which are connected to the hinge joints or leaf springs. The two machine parts are preferably rotated relative to one another about a rotational axis, preferably by actuating the actuator. In particular, the machine parts of the actuator

are connected to the torsion spring or the link arms by the interposition of the hinge joints or leaf springs. The actuator preferably has a motor or oscillating motor which, in particular, is a hydraulic oscillating motor. A hydraulic oscillating motor may relatively rapidly produce high torques with a comparatively small overall size. The machine parts may be connected to the oscillating motor or be part of the oscillating motor. For example, a first of the machine parts forms a rotor and a second of the machine parts forms a stator of the oscillating motor. Moreover, it is possible that at least one of the machine parts is connected to the oscillating motor by the interposition of a gear mechanism.
The link arms are preferably bent back by the torsion spring. In particular, the link arms are oriented obliquely, perpendicular or substantially perpendicular to the longitudinal axis of the torsion spring. The link arms preferably form a U-shaped profile together with the torsion spring. In particular, each of the link arms is connected fixedly in terms of rotation to the torsion spring.
The hinge axes of the hinge joints are preferably oriented perpendicular or substantially perpendicular to the longitudinal axis of the torsion spring and/or to the rotational axis of the actuator. Moreover, the planes of the leaves of the leaf springs are preferably oriented perpendicular or substantially perpendicular to the longitudinal axis of the torsion spring and/or to the rotational axis of the actuator.
The actuator is preferably connected to the hinge joints or leaf springs by the interposition of at least one elongate actuating member. In particular, the at least one actuating member is formed by a tube or bar, and preferably has a round cross section. Moreover, the at least one actuating member may be configured as a torsion spring. According to a development, the actuator is located between two actuating members and is connected thereby to the hinge joints or leaf springs.

The leaf springs may be connected without play to the actuator. The leaf springs may also be connected to the link arms without play. For example, bolt connections, screw connections or clamped connections may be used for forming the connections without play. For example, the leaf springs are connected to the actuator and/or to the link arms by connections with additional screw locking, producing a positive connection, or by clamped connections by means of screws, producing a frictional and/or non-positive connection. Also possible are connections by means of conical or spherical collar screws, producing positive or non-positive connections, as in a wheel fastening. Preferably, the leaf springs are connected both to the actuator and to the link arms by screw connections. In particular, each of the screw connections comprises at least two, preferably three screws.
The torsion spring is preferably formed by a tube, in particular by a tube with at least one longitudinal groove. As a result, very low torsional rigidity or residual rigidity may be achieved which, for example, also permits an operation of the stabiliser in the event of failure of the actuator or oscillating motor (fail-safe behaviour of the stabiliser). Alternatively, low torsional rigidity may also be achieved by an open profile. The cross section of the torsion spring is preferably round. According to a first variant of the invention, the actuator is arranged outside the torsion spring and at a distance therefrom. In this case, the rotational axis of the actuator or oscillating motor is preferably aligned in parallel with the longitudinal axis of the torsion spring. According to a second variant, the actuator is located in an interior of the torsion spring. In this case, the rotational axis of the actuator or oscillating motor preferably coincides with the longitudinal axis or longitudinal centre axis of the torsion spring.
The torsion spring is preferably mounted on a driver's cab of the utility vehicle, the link arms being connected to a vehicle chassis of the utility vehicle. In particular, the torsion spring is rotatably mounted on the driver's cab, preferably about the longitudinal axis or longitudinal centre axis of the torsion spring. The mounting of

the torsion spring on the driver's cab takes place, for example, via rotary bearings which are preferably provided with a sliding layer consisting of a sliding material for absorbing a pivoting movement and with a rubber layer for damping. In particular, the torsion spring is mounted on the driver's cab via rotary joints or rubber slide bearings. The link arms are connected to the vehicle chassis, for example, via rubber bearings. As a result, damping and uncoupling of vibrations may be achieved.
According to an alternative, the torsion spring is mounted on the vehicle chassis of the utility vehicle, the link arms being connected to the driver's cab of the utility vehicle. In particular, the torsion spring is rotatably mounted on the vehicle chassis, preferably about the longitudinal axis or longitudinal centre axis of the torsion spring. The torsion spring is mounted on the vehicle chassis, for example, via rotary bearings which are preferably provided with a sliding layer consisting of a sliding material for absorbing a pivoting movement and with a rubber layer for damping. In particular, the torsion spring is mounted on the driver's cab via rotary joints or rubber slide bearings. The link arms are connected to the driver's cab, for example via rubber bearings.
According to one embodiment, the stabiliser according to the invention consists of two lever arms and a connecting tube provided with at least one longitudinal groove. By means of said groove(s), the stabiliser obtains a very small amount of torsional rigidity (residual rigidity) but-remains resistant to bending. This may alternatively also be achieved by using an open profile. Parallel to the stabiliser tube an actuator is arranged which is connected on both sides to the stabiliser. As the hydraulic oscillating motor arranged in the actuator, however, only tolerates very small bending moments, a connecting solution is used in which no bending moments or only very small bending moments, produced by the rotation of the stabiliser and by lateral forces, act on the oscillating motor (during cornering). This is

achieved by the use of hinge joints and/ or leaf springs attached on both sides of the actuator.
By the use of hinge joints or leaf springs it is possible to transmit a torque of the oscillating motor to the stabiliser. Advantageously, in the case of joints, no bending moments are transmitted to the oscillating motor and/or, in the case of leaf springs, only very small bending moments resulting from the rotation and lateral forces are transmitted to the oscillating motor (during cornering). An additional advantage of the leaf springs is that the fastening thereof may be designed to be entirely without play. In this case, types of fastening are provided such as, for example, bolt connections (positive connection by a press fit) with additional screw locking, screw connections with spherical or conical collar screws (positive and frictional connection) or purely clamped/screw connections (frictional connection). Moreover, the use of leaf springs permits easy replacement of the actuator.
The invention further relates to the use of a stabiliser according to the invention for anti-roll stabilization of a driver's cab of a utility vehicle. Preferably, in this case, the driver's cab is connected to a vehicle chassis of the utility vehicle by means of the stabiliser. The anti-roll stabilization of the driver's cab is carried out, in particular, relative to the vehicle chassis.
The invention further relates to a utility vehicle, in particular a commercial vehicle, comprising a vehicle chassis and a driver's cab which is connected to the vehicle chassis by means of a stabiliser according to the invention.
The invention is disclosed hereinafter with reference to preferred embodiments, by referring to the drawings, in which:
Fig. 1 shows a partially perspective view of a utility vehicle comprising a
stabiliser according to a first embodiment of the invention,

Fig. 2 shows a perspective view of the stabiliser according to the first
embodiment,
Fig. 3 shows a perspective view of a stabiliser according to a second
embodiment of the invention and
Fig. 4 shows a perspective view of a stabiliser according to a third
embodiment of the invention.
In Fig. 1, a partially perspective view may be seen of a utility vehicle 1 comprising a driver's cab 2, on which a stabiliser 3 is rotatably mounted about an axis 4 according to a first embodiment of the invention. The stabiliser 3 has an elongate torsion spring 5, the longitudinal axis thereof coinciding with the axis 4. Link arms 6 and 7 (see Fig. 2) are connected fixedly in terms of rotation to the ends of the torsion spring 5, and which are connected to a vehicle chassis 9 of the utility vehicle 1 at a distance from the torsion spring 5 by the interposition of rubber bearings 8.
In Fig. 2, a perspective view of the stabiliser 3 according to the first embodiment may be seen, bearing receivers 10 and 11 being formed at the ends of the link arms 6 and 7 remote from the torsion spring 5 for receiving the rubber bearings 8. The stabiliser 3 has an actuator 12 formed as a hydraulic oscillating motor, by means of which two machine parts 13 and 14 may be rotated relative to one another about an axis 15, which is oriented parallel to the axis 4. The machine part 13 is connected fixedly in terms of rotation to one end of a connecting tube 16, the other end thereof being connected fixedly in terms of rotation to a leaf spring 17. Moreover, the machine part 14 is connected fixedly in terms of rotation to one end of a connecting tube 18, the other end thereof being connected fixedly in terms of rotation to a leaf spring 19. The connecting tube 16 is connected fixedly in terms of rotation to the leaf spring 17 by

screw connections 20. In a corresponding jnanner, the connecting tube 18 is screwed to the leaf spring 19.
The planes of the leaves of the leaf springs 17 and 19 run parallel to one another and are oriented perpendicular to the axes 4 and/or 15. Moreover, the leaf springs 17 and 19 are configured to be bent-back and/or the leaf springs 17 and 19 approximately follow the path of a quadrant. The end of the leaf spring 19 remote from the connecting tube 18 is connected to the link arm 7 by screw connections 21. In a corresponding manner, the end of the leaf spring 17 remote from the connecting tube 16 is screwed to the link arm 6. The torsion spring 5 has a longitudinal groove 22 so that the torsion spring 5 has low torsional stiffness with high bending stiffness at the same time.
In Fig. 3, a perspective view of a stabiliser 3 according to a second embodiment of the invention may be seen, similar or identical features to the first embodiment being denoted by the same reference numerals as in the first embodiment. The end of the connecting tube 16 remote from the machine part 13 is connected via a hinge joint 23 to one end of the torsion spring 5, the hinge joint 23 comprising a hinge axis 24 which is oriented perpendicular to the rotational axis 15 of the actuator. Moreover, the end of the connecting tube 18 remote from the machine part 14 is connected via a hinge joint 25 to the other end of the torsion spring 5, the hinge joint 25 having a hinge axis 26 which is oriented perpendicular to the rotational axis 15 of the actuator. Thus, in this case the leaf springs according to the first embodiment are replaced by the hinge joints. For the further description of the second embodiment, reference is made to the description of the first embodiment.
In Fig. 4, a perspective view of a stabiliser 3 according to a third embodiment of the invention may be seen, similar or identical features to the first embodiment being denoted by the same reference numerals as in the first embodiment. The torsion spring 5 is configured as an open hollow profile, the actuator 12 extending with the

machine parts 13 and 14 and with the connecting tubes 16 and 18 in the interior thereof. The rotational axis 15 of the actuator 12 coincides in this case with the longitudinal axis 4 of the torsion spring 5. The end of the connecting tube 16 remote from the machine part 13 is connected fixedly in terms of rotation to the leaf spring 17 by means of teeth 27 on the front face, in particular Hirth teeth. In a corresponding manner, the end of the connecting tube 18 remote from the machine part 14 is connected fixedly in terms of rotation to the leaf spring 19. The leaf springs 17 and 19 are, as in the first embodiment, connected by means of screw connections 21 to the link arms 6 and/or 7. For the further description of the third embodiment, reference is made to the description of the first embodiment.
More specifically, the actuator in the embodiments shown is arranged centrally between the leaf springs or hinge joints, but alternatively the actuator may also be arranged eccentrically or to the side. In this case, one of the connecting tubes may even be dispensed with if the actuator is directly fastened to one of the leaf springs or to one of the hinge joints.

List of reference numerals
1 Utility vehicle
2 Driver's cab
3 Stabiliser
4 Longitudinal axis of the torsion spring
5 Torsion spring
6 Link arm
7 Link arm
8 Rubber bearing
9 Vehicle chassis
10 Bearing receiver
11 Bearing receiver
12 Actuator
13 Machine part
14 Machine part
15 Rotational axis of the actuator
16 Connecting tube
17 Leaf spring
18 Connecting tube
19 Leaf spring
20 Screw connection
21 Screw connection
22 Longitudinal groove
23 Hinge joint
24 Hinge axis
25 Hinge joint
26 Hinge axis
27 Teeth

WE CLAIM:
1. Stabiliser for a utility vehicle, comprising an elongate torsion spring (5), two link arms (6, 7) fixedly connected to the torsion spring (5) and extending away from said torsion spring, between which the torsion spring (5) extends, characterised by an actuator (12) arranged in parallel with the torsion spring (5) and which is connected to the torsion spring (5) or to the link arms (6, 7) by the interposition of hinge joints (23,25) or leaf springs (17,19).
2. Stabiliser according to Claim 1, characterised in that the link arms (6, 7) are oriented perpendicular or substantially perpendicular to the longitudinal axis
(4) of the torsion spring (5).
3. Stabiliser according to Claim 1 or 2, characterised in that the hinge axes (24, 26) of the hinge joints (23, 25) are oriented perpendicular or substantially perpendicular to the longitudinal axis (4) of the torsion spring (5) and/or to a rotational axis (15) of the actuator (12).
4. Stabiliser according to one of the preceding claims, characterised in that the planes of the leaves of the leaf springs (17,19) are oriented perpendicular or substantially perpendicular to the longitudinal axis (4) of the torsion spring
(5) and/or to a rotational axis (15) of the actuator (12).
5. Stabiliser according to one of the preceding claims, characterised in that the actuator (12) comprises two machine parts (13, 14) which may be rotated relative to one another, and which are connected to the hinge joints (23, 25) or leaf springs (17, 19) and are rotated or may be rotated (12) relative to one another about a rotational axis (15) by actuating the actuator.
6. Stabiliser according to one of the preceding claims, characterised in that the actuator (12) comprises a hydraulic oscillating motor.

7. Stabiliser according to one of the preceding claims, characterised in that the actuator (12) is connected to the hinge joints (23, 25) or leaf springs (17,19) by the interposition of at least one elongate actuating member (16,18).
8. Stabiliser according to Claim 7, characterised in that the at least one actuating member (16,18) is formed by a round tube or bar.
9. Stabiliser according to one of the preceding claims, characterised in that the leaf springs (17, 19) are connected both to the actuator (12) and to the link arms (6, 7) by screw connections (20,21).
10. Stabiliser according to one of the preceding claims, characterised in that the torsion spring (5) is formed by a tube with at least one longitudinal groove (22).
11. Stabiliser according to one of the preceding claims, characterised in that the torsion spring (5) has an open profile.
12. Stabiliser according to one of the preceding claims, characterised in that the actuator (12) is arranged outside the torsion spring (5) and comprises a rotational axis (15) extending in parallel with the torsion spring (4).
13. Stabiliser according to one of Claims 1 to 11, characterised in that the actuator (12) is located in an interior of the torsion spring (5).
14. Stabiliser according to one of the preceding claims, characterised in that the torsion spring (5) is rotatably mounted on a driver's cab (2) of the utility vehicle (1), the link arms (6, 7) being connected to a vehicle chassis (9) of the utility vehicle (1).

15. Stabiliser according to one of the preceding claims, characterised in that the actuator (12) is connected on both sides to the link arms (6, 7) or the ends of the torsion spring (5) by the interposition of the hinge joints (23, 25) or leaf springs (17,19).