AUTOMOBILE SUSPENSION SYSTEM WITH VARIABLE VEHICLE BODY RIDE

Abstract

A motor vehicle wheel suspension system comprising, on each side of a vehicle chassis (2), a suspension arm (8) arranged substantially along the longitudinal direction of the vehicle, comprising at one end a pivot (6) connected to the chassis having a transverse axis, at the other end (10) a suspension spring (12) connected to this chassis, and comprising between the two ends a wheel hub support (28) equipped with a brake (34), the suspension arm (8) comprising two parts (20, 22) connected to each other by a joint (24) having a transverse axis, and a locking mechanism (26) for this joint (24) in several angular positions, the wheel hub (28) being on the part of the arm (22) which, during braking of the wheel (30), applies a reaction torque to it which tends to lower the joint (24). Figure 1

Description

Title of the invention: AUTOMOBILE SUSPENSION SYSTEM WITH VARIABLE VEHICLE BODY REACH

[0001] The present invention relates to a motor vehicle suspension system comprising a vehicle body ride height which is variable, as well as a motor vehicle equipped with such a suspension system and a method for controlling the suspension of this vehicle.

[0002] A known type of vehicle suspension, presented in particular by document US-A-5332258, includes a rigid rear axle connected on each side to the chassis by an air suspension spring arranged in series with a pneumatic chassis height control element.

[0003] Each side of the vehicle comprises an arm arranged substantially longitudinally under the chassis, having at one front end a transverse pivot fixed to this chassis. A pneumatic vehicle trim control element, comprising a variable length, bears against the underside of the chassis to press above the rear end of the arm in order to change its distance from the chassis.

[0004] A leaf suspension spring disposed under the arm, supporting in a central part the axis of the rear axle, has a front end connected to the chassis by the same transverse pivot, the other end receiving the air suspension spring which bears support under the rear end of this arm.

[0005] A telescopic shock absorber connects the rigid rear axle to the arm in order to dampen the movements of the suspension between these two elements to ensure comfort and road holding.

[0006] A suspension movement is obtained with the leaf spring oscillating around its front pivot, by compressing the suspension spring which bears support under the rear end of the longitudinal arm.

[0007] Furthermore, by adjusting the length of the pneumatic control element, a shorter length brings the chassis closer to the rear end of the arm that forms the fulcrum of the suspension spring, lowering the chassis and giving the vehicle a lower seating position. Conversely, a longer length moves the chassis further away from the rear end of the arm, raising the chassis and giving the vehicle a higher seating position.

[0008] However, this type of suspension, which allows for a variable vehicle seating position, uses a height control element powered by an energy source that must allow lifting the mass of the vehicle, in particular by delivering significant power if we want to obtain a rapid action of this function.

[0009] In particular, some vehicles can lower their pitch to improve aerodynamics at higher speeds, or all-terrain vehicles can raise their pitch to increase ground clearance depending on the terrain.

[0010] It is then necessary to provide on each side of the vehicle a sufficiently powerful height control element which poses problems of energy consumption, size and mass, and of costs of supplying components and assembly labor.

[0011] The present invention is specifically intended to avoid these problems of the prior art.

[0012] To this end, it proposes a motor vehicle wheel suspension system comprising on each side of a vehicle chassis a suspension arm arranged substantially along the longitudinal direction of the vehicle, comprising at one end a pivot for connecting to the chassis having a transverse axis, at the second end a suspension spring connected to this chassis, and comprising between the two ends a wheel hub support equipped with a brake, this suspension system being remarkable in that the suspension arm comprises two parts connected to each other by a joint having a transverse axis, and a locking mechanism for this joint in several angular positions, the wheel hub being on the part of the arm which, when the wheel is braked, applies a reaction torque which tends to lower the joint.

[0013] An advantage of this suspension system is that when braking the vehicle, the effect of the braking torque on the wheel produces a reaction torque which the brake applies to the suspension arm, which, by lowering the intermediate joint, tends to raise the ends of the arm connected to the chassis.

[0014] It is then possible, with a control of the locking mechanism taking into account both the request for variation of attitude and the reaction torque on the arm during braking of the vehicle, to unlock the joint to take advantage of this reaction torque in order to obtain the lifting of the body, and then to lock it again when the required height is obtained.

[0015] A suspension system is developed that allows for variation in vehicle pitch, in particular raising the vehicle body, which utilizes the energy of the powertrain and brakes without requiring the installation of an additional power-delivering and energy-consuming system. The variable pitch suspension system is simple, compact, and economical.

[0016] The suspension system according to the invention may further comprise one or more of the following features, which may be combined with each other.

[0017] Advantageously, the joint includes a system for damping its movement.

[0018] In this case, advantageously the travel damping system includes a brake with variable clamping, which can block the joint by constituting the locking mechanism.

[0019] Alternatively, the locking mechanism may include positive locking positions that are spaced apart.

[0020] Advantageously, the suspension system includes a sensor for the angular position of the joint.

[0021] Advantageously, the joint has end stops on each side of its stroke.

[0022] In particular, the first end pivot can be turned towards the front of the vehicle.

[0023] The invention also relates to a motor vehicle, remarkable in that it includes a suspension system comprising any one of the preceding characteristics.

[0024] The invention further relates to a method of controlling the suspension of a motor vehicle comprising a suspension system including any of the preceding characteristics, remarkable in that for an increase in the vehicle's ride height, during wheel braking it successively applies an unlocking and then a locking of the locking mechanism.

[0025] Furthermore, for a reduction in the vehicle's ride height, the method can successively apply an unlocking and then a locking of the locking mechanism, allowing the mass of the vehicle to apply a force that causes the joint to bend.

[0026] The invention will be better understood and other features and advantages will become more apparent upon reading the following description given by way of example, with reference to the accompanying drawings in which:

[0027] [Fig.l] is a side view diagram of a suspension system according to the invention arranged in a median position;

[0028] [Fig.2] presents this suspension system which raises the vehicle chassis seat during braking;

[0029] [Fig.3] presents this suspension system with a high seat;

[0030] [Fig.4] presents this suspension system which lowers the seat; and

[0031] [Fig.5] presents this suspension system with a low seat.

[0032] Throughout the document, the upper or top direction is relative to a vehicle placed on a horizontal ground, the transverse direction is perpendicular to the longitudinal axis of the vehicle, the forward direction (AV) is the direction of travel of the vehicle.

[0033] Fig. 1 shows the suspension of a rear axle comprising a vertical support 4 fixed under a chassis longitudinal member 2 ending in a front pivot 6 having a transverse axis receiving the front end of a suspension arm 8 arranged substantially longitudinally.

[0034] The rear end of the suspension arm 8 has a rear pivot 10 having a transverse axis, which connects it to the base of a suspension unit 12 having a spring surrounding a telescopic shock absorber fixed by an upper pivot 14 under the chassis rail 2.

[0035] The suspension arm 8 comprises two elongated parts 20, 22 connected to each other by a joint 24 having a transverse articulation axis, having a locking mechanism 26 which allows these two parts to be locked together in several angular positions.

[0036] The front part of the arm 20, representing approximately one-third of the length of the complete arm 8, connects the front pivot 6 to the joint 24. The rear part of the arm 22, connecting the joint 24 to the rear pivot 10, has in a central position the hub 28 of a wheel 30 comprising a brake disc 32 clamped by a brake caliper 34 fixed to this rear part of the arm.

[0037] With the joint 24 blocked by the locking mechanism 26 in any of its possible angular positions, during the rolling of the vehicle, a movement of the entire arm 8 around its front pivot 6 is obtained by compressing the spring of the suspension unit 12 which provides the suspension function.

[0038] With two arm sections 20, 22 aligned, the wheel hub 28 is aligned between the front pivot 6 and the rear pivot 10, resulting in a mid-position for the chassis height 2. Lowering the joint 24, which positions these pairs of arms 20, 22 at an upward angle, raises the rear pivot 10 and the chassis 2, increasing the vehicle's ride height. Raising the joint 24, which positions the arm sections at a downward angle, lowers the rear pivot 10, decreasing the ride height.

[0039] The joint 24 has end stops limiting in both directions the angular movement of the two arm parts 20, 22 between them, so as to avoid in all operating cases of the locking mechanism 26 an extreme position which could damage elements.

[0040] A vehicle control computer takes into account the request to modify the vehicle's attitude, which can be manual with a request from the driver, or automatic depending on various operating parameters of this vehicle, in particular to respond to a change in its load requiring lifting. of the vehicle in order to compensate for compression of the suspension units 12, to an increase in ground clearance in the case of a road in poor condition, or to an improvement in its aerodynamics at high speeds by reducing the vehicle's attitude.

[0041] The suspension includes a sensor for the angular position of the joint 24, delivering a signal to the control computer so that it can follow the value of this angular position and its evolution.

[0042] The control computer also takes into account vehicle driving parameters such as its acceleration or braking, to control the modification of the ride height.

[0043] Fig. 2 shows, from a median height H of the chassis 2, for a request to increase the ride height, during the next braking of the vehicle, the brake caliper 34 fixed to the rear part of the arm 22 which applies the reaction torque CR coming from the wheel 30 on this rear part of the arm, tending to rotate it in the clockwise direction.

[0044] In this case, the locking mechanism 26 is opened, and the reaction torque CR is allowed to rotate the rear part of the arm 22 clockwise, lowering the joint 24, which at the same time raises the suspension assembly 12 and the height of the chassis 2.

[0045] In addition, for a rear suspension, the vehicle's braking gives a dynamic reaction torque on the body tending to lift its rear by unloading it, which can be taken into account by the computer to increase the speed of movement of the joint 24.

[0046] Fig. 3 shows the chassis 2 at the desired high height Hl, the control computer which blocks the locking mechanism 26 in order to permanently maintain the higher vehicle position requested.

[0047] The [Fig.4] shows, from the high height Hl, for a request to reduce the ride height, an opening of the locking mechanism 26 which allows, by the weight of the vehicle applying a force F on the suspension assembly 12, a descent of the rear pivot 10, and at the same time a folding of the joint 24 which rises.

[0048] Fig. 5 shows the chassis 2 at the desired low height H2, the control computer which blocks the locking mechanism 26 in order to permanently maintain the lower vehicle position requested.

[0049] Preferably, the joint 24 includes a system for damping its movement, for example a braked sliding system, so as to obtain smooth and not too rapid movements of the folding in either direction of this joint, allowing the locking mechanism to lock the joint at the required moment during its raising or lowering. In particular, a locking mechanism 26 may be provided, comprising a brake that provides a slight clamping action. A predetermined friction torque is applied during the movements of joint 24 to control them, and is then tightly clamped in the expected position to lock the joint. In this case, there is a continuous range for the locking capability of joint 24.

[0050] In addition, the locking mechanism 26 may include spaced positive locking positions, such as engaged notches, which fix a number of predefined positions.

[0051] In the example presented, the suspension unit 12 being located behind the wheel 30, the geometry of the suspension arm 8 gives an amplification of the travel of the wheel 30 applied to this unit.

[0052] In all cases, we obtain a vehicle leveling system that does not use clean energy, making it a relatively simple and economical system.

Claims

Demands

1. A motor vehicle wheel suspension system comprising on each side of a vehicle chassis (2) a suspension arm (8) disposed substantially along the longitudinal direction of the vehicle, comprising at a first end a pivot (6) for connection to the chassis (2) having a transverse axis, at the second end (10) a suspension spring (12) connected to this chassis (2), and comprising between the two ends a wheel hub support (28) equipped with a brake (34), characterized in that the suspension arm (8) comprises two parts (20, 22) connected to each other by a joint (24) having a transverse axis, and a locking mechanism (26) for this joint (24) in several angular positions, the wheel hub (28) being on the part of the arm (22) which, during braking of the wheel (30), applies a reaction torque (CR) which tends to lower the joint (24).

2. Suspension system according to claim 1, characterized in that the joint (24) includes a system for damping its movement.

3. Suspension system according to claim 2, characterized in that the travel damping system includes a brake having variable clamping, which can block the joint (24) by constituting the locking mechanism (26).

4. Suspension system according to claim 1 or 2, characterized in that the locking mechanism (26) has positive locking positions which are spaced apart.

5. Suspension system according to any one of the preceding claims, characterized in that it comprises a sensor for the angular position of the joint (24).

6. Suspension system according to any one of the preceding claims, characterized in that the joint (24) has end stops on each side of its stroke.

7. Suspension system according to any one of the preceding claims, characterized in that the first end pivot (6) is turned towards the front of the vehicle.

8. Motor vehicle, characterized in that it comprises a suspension system according to any one of the preceding claims.

9. A method for controlling the suspension of a motor vehicle according to claim 8, characterized in that for an increase in the vehicle's ride height, during braking of the wheel (30) it successively applies an unlocking and then a locking of the locking mechanism (26).

10. Suspension control method according to claim 9, characterized in that for a decrease in the vehicle's ride height it successively applies an unlocking and then a locking of the locking mechanism (26) by allowing the mass of the vehicle to apply a force (F) which causes the joint (24) to bend.