The present application claims priority to European Patent Application No. 20179191.0, filed on Jun. 10, 2020, and entitled “AN ADJUSTABLE ANTI-ROLL BAR ARRANGEMENT,” which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The invention relates to an adjustable anti-roll bar arrangement for a vehicle. The invention also relates to a vehicle comprising such an anti-roll bar arrangement.

The invention can be applied in heavy-duty vehicles, such as trucks, buses, and construction equipment. Although the invention will be described with respect to a heavy-duty vehicle such as a truck, the invention is not restricted to this particular vehicle but may also be used in other vehicles such as passenger cars.

BACKGROUND

An anti-roll bar may form part of the suspension system of a vehicle. Its purpose is to reduce the roll of the vehicle, for example during fast cornering or when the vehicle runs on a rough road with irregularities in the road surface.

For a truck, the roll stiffness in today's anti-roll bars is normally selected upon order and it stays the same for the entire life cycle of the truck. However, under certain conditions it may sometimes be desirable to have higher roll stiffness than the pre-selected one, while in other cases it may be desirable to have lower roll stiffness than the pre-selected one. For instance, a driver may wish to lower the truck to reduce drag, and in such case it would be desirable to increase the roll stiffness. On the other hand, when a truck is driving on a bumpy road, it would be desirable to decrease the roll stiffness.

U.S. Pat. No. 8,608,186 B2 discloses an active roll control system that may be adapted to actively control roll stiffness of a vehicle by adjusting a mounting position of a stabilizer link connecting a stabilizer arm with a stabilizer bar of the vehicle on the suspension arm.

However, while this system may work on a small passenger car, it is inadequate for the high loads of a truck.

SUMMARY

An object of the invention is to provide an adjustable anti-roll bar arrangement which at least partly alleviates the drawbacks of the prior art. In particular, it should be suitable for implementation on a heavy duty vehicle, such as a truck. The object is achieved by an adjustable anti-roll bar arrangement according to claim1.

The present invention is not only based on the possibility to change the position of a stabilizer stay to change the roll stiffness, but is in particular based on the realization that by separating a linear displacement of the stabilizer stay from a linear drive axis, the arrangement may take higher loads than if the displacement of the stabilizer stay and the linear drive axis is the same. Thus, the inventors have realized that carrying loads of the anti-roll bar and the stabilizer stay may be achieved by one component (such as a supporting shaft), while the energy supply (such as a linear actuator) for achieving the movement of the stabilizer stay may be provided on another component. Put differently, the adjustable anti-roll bar arrangement may have a translation mechanism which is arranged separately from a supporting structure of the arrangement.

According to a first aspect of the invention, there is provided an adjustable anti-roll bar arrangement for a vehicle, comprisinga bracket configured to be mounted in a fixed relationship to a chassis or a an axle of the vehicle,a linear actuator connected to the bracket,a guided element, wherein the linear actuator is configured to drive the guided element along a first geometrical axis,a supporting shaft mounted to the bracket and defining a second geometrical axis, the second geometrical axis having a different extension compared to the first geometrical axis,an anti-roll bar, anda stabilizer stay having a first end connected to the anti-roll bar, and a second end movably connected to and supported by the supporting shaft,wherein the second end of the stabilizer stay is also connected to the guided element such that when the linear actuator drives the guided element along the first geometrical axis, the second end of the stabilizer stay follows the motion along said second geometrical axis.

By having the linear actuator drive the guided element along a first geometrical axis and having the load-carrying supporting shaft on a second geometrical axis which is different from the first geometrical axis, the risk of braking the arrangement is greatly reduced.

By changing the position of the second end of the stabilizer stay, the lever action provided by the arrangement is changed, and thereby the roll stiffness of the vehicle can be changed. Moving the second end of the stabilizer stay in an inboard direction, i.e. closer towards the centre of the vehicle, results in lowered roll stiffness. Conversely, moving the second end of the stabilizer stay in an outboard direction, i.e. laterally away from the centre of the vehicle, results in an increased roll stiffness.

The linear actuator may either be directly connected to the bracket or indirectly connected to the bracket. For instance, in the second case, the linear actuator may be connected to another bracket unit or to a cover or the like, which in turn is mounted to the bracket. In other exemplary embodiments, the linear drive may be mounted on a cradle, which in turn may be pivotally attached to the bracket.

The linear actuator may be any suitably type of actuator which conveys a linear motion. It may for instance include electrically, hydraulically, pneumatically, or otherwise generated driving power to the guided element. The guided element may be guided along a physical linear axle or shaft or the like, or may be guided along just a geometrical axis. For instance, the guided element may be provided at the end of a hydraulic or pneumatic piston rod, or may form part of such a piston rod.

The supporting shaft may be any suitable shaft for carry the displaceable stabilizer stay and the anti-roll bar. If the stabilizer stay and the supporting shaft is for example configured to be arranged on the left side of the vehicle, then it should be understood that the anti-roll bar may, of course, have another stabilizer stay at its other end to be carried by another support structure at the right side of the vehicle. In some exemplary embodiments both the left and the right stabilizer stays may be movably connected in accordance with the herein described mechanisms of the invention, while in other exemplary embodiments, only one of the left and right stabilizer stays is movably connected and supported, while the other one is fixedly connected and supported.

The supporting shaft may also be mounted to the bracket directly or indirectly. For instance, in the latter case, the supporting shaft may be mounted to a cradle which may be pivotally attached to the bracket. The supporting shaft may suitable have two ends, each end being fixed to a respective structure. Thus, one end may be fixed to the bracket or to another component (such as a cradle) attached to the bracket, while the other end may be fixed to another bracket unit (such as one that forms a cover, casing or housing).

According to at least one exemplary embodiment, said second geometrical axis is parallel to said first geometrical axis, wherein when the linear actuator drives the guided element along said first geometrical axis, the second end of the stabilizer stay follows the motion in parallel along said second geometrical axis. By having the first and the second geometrical axis in parallel with each other the driving force acting on the guided element may be transmitted to in a simple manner to the second end of the stabilizer stay. Thus, the guided element does not need any complex linkage but may, for instance, be in the form of a rigid body. However, it should be understood, that in other exemplary embodiments the first and the second geometrical axes are not parallel with each other, they may thus be inclined relative to each other. In such, case the linear motion of the guided element along the first geometrical axis may suitable be transferred to the second end of the stabilizer stay via suitable linkage, joints, or the like.

According to at least one exemplary embodiment, the bracket comprises a first side and a second side, wherein the first side faces the second end of the stabilizer stay, wherein the roll stiffness is increased when the second end of the stabilizer stay is moved in a direction towards the bracket, and decreased when the second end of the stabilizer stay is moved in a direction away from the bracket. However, depending on how and where the bracket is mounted relative to the vehicle, such as relative to the chassis of the vehicle, in other exemplary embodiments, the roll stiffness may decrease when the second end of the stabilizer stay is moved towards the bracket, and increase when it is moved away from the bracket.

According to at least one exemplary embodiment the bracket comprises an inboard side and an outboard side, the inboard side being intended to face the centre of the vehicle. In at least some exemplary embodiments (for instance when the bracket is configured to be mounted inboardly of the chassis) the inboard side faces the second end of the stabilizer stay, wherein the roll stiffness is increased when the second end of the stabilizer stay is moved in a direction towards the bracket and decreased when the second end of the stabilizer stay is moved in a direction away from the bracket. In other exemplary embodiments (for instance when the bracket is configured to be mounted outboardly of the chassis), the outboard side faces the second end of the stabilizer stay, wherein the roll stiffness is decreased when the second end of the stabilizer stay is moved towards the bracket and increased when the second end of the stabilizer stay is moved away from the bracket.

As mentioned previously, an anti-roll bar is normally connected via two stabilizer stays, one at each respective end of the anti-roll bar. As also mentioned previously, in some exemplary embodiments both such stabilizer stays may be movable for adjusting the roll stiffness of the vehicle, while in some exemplary embodiments, only one of the stabilizer stays is movable for adjusting the roll stiffness.

Having both stabilizer stays movable is reflected in at least one exemplary embodiment, according to which said anti-roll bar has a left side and a right side, wherein said bracket, said linear actuator, said guided element, said supporting shaft and said stabilizing stay form a set provided on one of the left side and right side of the anti-roll bar, wherein a corresponding set is provided mirror-symmetrically on the other one of the left side and right side of the anti-roll bar.

The direction of movement of the stabilizer stay when changing the roll stiffness may suitably be a direction closer to or further away from the other stabilizer stay. This is reflected in the below exemplified embodiments.

Thus, according to at least one exemplary embodiment, said stabilizer stay is a first stabilizer stay located at one end of the anti-roll bar, wherein the adjustable anti-roll bar arrangement further comprises another stabilizer stay located at the other end of the anti-roll bar, wherein when the second end of the first stabilizer stay moves towards said another stabilizer stay the roll stiffness is decreased, and when the second end of the first stabilizer stay moves in a direction away from said another stabilizer stay the roll stiffness is increased.

The first end of the stabilizer stay is suitably substantially stationary relative to the anti-roll. Since the second end is movable, the movement results in a change of inclination relative to the anti-roll bar. Thus, the movement of the anti-roll bar may also be expressed as an angular change. For instance, according to at least one exemplary embodiment, the stabilizer stay form an angle relative to the anti-roll bar, wherein when said angle is increased then the roll stiffness is increased, and when said angle is decreased then the roll stiffness is decreased.

As mentioned previously, various types of linear actuators may be implemented in the adjustable anti-roll bar arrangement. According to at least one exemplary embodiment, the linear actuator comprises an electric motor and a guide shaft defining the first geometrical axis, wherein the electric motor is configured to drive the guided element along said guide shaft. In some exemplary embodiments, the linear actuator may also comprise a set of gears for converting the rotational motion of the electric motor to a linear motion of a spindle or other component. In some exemplary embodiments, the rotational motion of the motor can be transmitted to rotation of the guide shaft, which may suitably function as a lead screw. This is reflected in the following exemplary embodiment.

According to at least one exemplary embodiment, said guide shaft is a lead screw provided with male threads, wherein the guided element is provided with female threads engaging the male threads, wherein the electric motor is configured to rotate the lead screw, wherein the guided element moves along the lead screw when the lead screw is rotated. Thus, the guide shaft in the form of a lead screw defines the first geometrical axis.

According to at least one exemplary embodiment, the adjustable anti-roll bar arrangement comprises a pivotable element which is pivotally mounted to the bracket via a pivot axle, wherein the supporting shaft is connected to the pivotable element such that when the pivotable element pivots about the pivot axle, the supporting shaft, the linear actuator and the guided element follows the pivoting motion of the pivotable element. Thus, the pivotable element may function as a cradle which compensates for unevenness of the road surface.

According to at least one exemplary embodiment,

said supporting shaft is a first supporting shaft,

said anti-roll bar is a first anti-roll bar, and

said stabilizer stay is a first stabilizer stay,

wherein the adjustable anti-roll bar arrangement is configured for a double-axle installation (double-axle aggregate) by further comprising:

a second anti-roll bar, and

a second stabilizer stay, and

optionally, a second supporting shaft mounted to the bracket and defining a third geometrical axis,

wherein the second stabilizer stay has a first end connected to the second anti-roll bar, and a second end movably connected to and supported by the first supporting shaft or by said optional second supporting shaft,

wherein the second end of the second stabilizer stay is also connected to the guided element such that when the linear actuator drives the guided element along the first geometrical axis, the second end of the second stabilizer stay follows the motion along said second or third geometrical axis.

Thus, at least some exemplary embodiments may suitably be implemented for a double-axle aggregate, typically at rear wheels. The each wheel axle is paired with a respective one of the anti-roll bars. Each anti-roll bar may have at least one movable stabilizer stay. The movable stabilizer stays on the same side of the anti-roll bar, for example both left side stabilizer stays, extend from their respective anti-roll bar and may suitable be connected to the same supporting shaft, i.e. the first supporting shaft. In other exemplary embodiments, the second end of the respective stabilizer stay may be connected to a respective supporting shaft. In case of a common supporting shaft, first geometrical axis may suitably be located in the same vertical plane as the second geometrical axis, i.e. one above the other. In case of separate supporting shafts, the second and third geometrical axes may suitably be located on either side of the first geometrical axis. This is reflected in the following exemplary embodiment.

According to at least one exemplary embodiment, the first, second and third geometrical axes are located in a first, second and third geometric plane, respectively, wherein said first, second and third geometric planes extend in parallel with each other, and wherein the first geometric plane is located in between the second and third geometric planes. It should be understood that the first, second and third geometrical axes do not necessarily have to be located in the same horizontal plane but can be vertically displaced relative to each other. For instance, the second and third geometrical axes may be located in a common horizontal plane while the first geometrical axis is located in a different horizontal plane. Furthermore, it should be understood that it is not necessary for the first, second and third geometrical axes to be located in horizontal planes, they could be located in inclined planes.

According to at least one exemplary embodiment, the adjustable anti-roll bar arrangement comprises a controller configured to receive an input signal and based on the input signal send a control signal to the linear actuator to activate the linear actuator to move the guided element. This is beneficial as it provides an efficient adjustability of the roll stiffness of the vehicle. The adjustability may either be manual, for instance via a user interface, such as in a vehicle cabin, or the adjustability may be automatic, such as sensor-based.

Thus, according to at least one exemplary embodiment, the input signal is one of:

a driver command signal representative of a driver request for change of roll stiffness of the vehicle, and

a sensor signal received from a sensor configured to detect vehicle operating parameters and/or road surface roughness variations.

Some examples of conceivable sensors for providing the sensor signal are level sensors, steering angle sensor, lateral acceleration sensors, load sensors and speed sensors. Furthermore, the controller may suitably receive more than one sensor signals, and act accordingly. For instance, the steering angle sensor, may provide indications of the bumpiness of the road, and the roll stiffness may suitably be adjusted differently depending on the speed of the vehicle on the bumpy road.

According to a second aspect of the invention, there is provided a vehicle comprising an adjustable anti-roll bar arrangement according to the first aspect of the invention, including any embodiment thereof.

A vehicle is normally defined by a geometrical roll axis, which extends in the longitudinal direction of the vehicle, i.e. the normal driving direction. A vehicle is also defined by a geometrical pitch axis extending in the lateral or transverse direction of the vehicle, i.e. from left to right or vice versa. Furthermore, a vehicle is defined by a yaw axis extending in the vertical direction, i.e. from the ground and up through the vehicle. Together, the roll axis, the pitch axis and the yaw axis for orthogonal coordinate axes.

According to at least one exemplary embodiment, said first geometrical axis extends in parallel to the pitch axis. Thus, the linear movement of the guided element is towards the centre of the vehicle or laterally away (such as to the left or right side) of the vehicle.

According to at least one exemplary embodiment, the movement of the second end of the stabilizer stay towards the centre of the vehicle decreases the roll stiffness of the vehicle, and movement of the second end of the stabilizer stay away from the centre of the vehicle increases the roll stiffness of the vehicle. This movement may, for instance, be in parallel with the pitch axis. By changing the lateral or transverse position of the second end of the stabilizer stay, the lever effect around the roll axis of the vehicle is changed, thus affecting the roll stiffness of the vehicle.

Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims.

