AUTOMOTIVE VEHICLE SUSPENSION SYSTEM WITH ENERGY RECOVERY DEVICE

Abstract

A motor vehicle suspension system comprising an energy recovery device including a fixed part (30) connected to the vehicle chassis and a moving part (32) connected to a suspension element of a vehicle wheel, which generates an electric current during the movements between these two parts. This energy recovery device forms an independent subassembly (20) comprising a cylinder with a piston displaced by the movements between the two parts (30, 32), separating two chambers, a turbine powered by the air compressed by the piston, and an electric generator driven by this turbine. Figure 1

Description

Title of the invention: AUTOMOBILE SUSPENSION SYSTEM WITH ENERGY RECOVERY DEVICE

[0001] The present invention relates to a motor vehicle suspension system with an energy recovery device, as well as a motor vehicle equipped with such a suspension system.

[0002] The wheels of motor vehicles include a suspension generally comprising a hydraulic shock absorber arranged in parallel with a spring, which dampens the travel movements of this spring to ensure comfort and road holding, with energy dissipation through calibrated drilling of the fluid passage generating heat which is lost.

[0003] A type of motor vehicle suspension system known, notably presented in document US-A1-20120313775, includes a cylinder arranged in parallel with a shock absorber which, during suspension travel, compresses a hydraulic fluid to send it to a remote pressure accumulator constituting an energy reserve.

[0004] The pressurized fluid is then used to turn an alternator generating electricity, in order to transform the mechanical energy of the suspension movements into electrical energy used to recharge the vehicle's battery, thus limiting the power taken from the vehicle's internal combustion engine to charge it, which saves energy.

[0005] Another known type of suspension system, described in particular by document WO-A1-2023136543, comprises a rocker arm connected on one side to a suspension element and on the other side to a linear electric generator that converts the suspension travel movement into electricity stored in a separately located capacitor. The electrical energy from the capacitor is then adapted to be sent to the vehicle's battery for recharging.

[0006] In both cases, the energy recovery system requires elements that are located away from the suspension, including for the first type of suspension system presented a tank connected by fluid pipes, and for the second type of system an electric generator connected by the lever, which poses space problems under the vehicle.

[0007] Moreover, for the rocker arm of the second type of suspension system, its geometry requires a particular positioning on the running gear which is difficult to predict in most vehicles.

[0008] In all cases, systems are obtained comprising complex links between the elements, which require assembly times and result in higher costs.

[0009] The present invention is specifically intended to avoid these problems of the prior art.

[0010] To this end, it proposes a motor vehicle suspension system comprising an energy recovery device comprising a fixed part linked to the vehicle chassis and a moving part linked to a suspension element of a wheel of the vehicle, which generates an electric current during the movements between these two parts, this system being remarkable in that the energy recovery device forms an independent subassembly comprising a cylinder with a piston moved by the movements between the two parts, separating two chambers, a turbine powered by the air compressed by the piston, and an electric generator driven by this turbine.

[0011] One advantage of this suspension system is that by carrying out in an integrated manner in the same sub-assembly both the transformation of the mechanical suspension movement into compressed air, and then the recovery of the energy of this air into an electric current delivered by the generator driven by the turbine, it is then sufficient to have an electric cable which can easily find a passage in the vehicle to transmit this energy to a storage device such as a battery.

[0012] The sub-assembly can thus be fixed as close as possible to the vehicle's suspension, for example on the two sliding tubes of a shock absorber of this suspension, and then with a simple electrical cable connect the sub-assemblies of each wheel to the energy storage device, which represents a compact and simple connection to install.

[0013] The suspension system according to the invention may further comprise one or more of the following features, which may be combined with each other.

[0014] Advantageously, the suspension system includes a first check valve which supplies the turbine from a second chamber of the cylinder.

[0015] In this case, advantageously the suspension system includes a return pipe which connects the turbine outlet to a first chamber of the cylinder opposite the second chamber, and includes a second check valve which allows passage from the first chamber to the second chamber.

[0016] Alternatively, the suspension system may include a set of check valves straightening the airflow to supply the turbine from the two chambers for suspension movements in both directions.

[0017] Advantageously, the turbine and the electric generator are mounted on the same rotating shaft.

[0018] Advantageously, the two parts of the energy recovery device are connected to the two moving elements of a hydraulic damper.

[0019] In this case, the energy recovery device can form a cylindrical pot which is fixed parallel to the shock absorber by two arms each connected to one side of this shock absorber.

[0020] The invention also relates to a motor vehicle comprising wheel suspensions, with a suspension system comprising any one of the preceding characteristics which is disposed on each wheel of a wheel assembly.

[0021] Advantageously, the vehicle includes energy recovery devices that recharge the on-board network battery.

[0022] Advantageously, the energy recovery devices are fixed on the two shock absorbers of the same wheel assembly.

[0023] 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:

[0024] [Fig-1] is a view of a suspension system according to the invention comprising the sub- assembly fixed to the side of a telescopic shock absorber presented in two positions: relaxed and then compressed;

[0025] [Fig.2] is an axial cross-sectional view of this suspension system in its compressed position;

[0026] [Fig.3] is an exploded view of the subassembly; and

[0027] [Fig.4] is a diagram of an example circuit of this system.

[0028] Throughout this document, the upper or top direction refers to a vehicle resting on a horizontal surface. The shock absorber and energy recovery device may be mounted in the vehicle in any orientation other than that shown in the figures.

[0029] Figures 1, 2 and 3 show a suspension assembly comprising a helical spring 2 surrounding a vertically arranged hydraulic telescopic shock absorber 4, having in its lower part a tubular body 6 ending in a lower ring 8 fixed on a movable element of the suspension of a wheel of the vehicle, and in its upper part a rod 10 ending in an upper ring 12 for fixing to the body of the vehicle.

[0030] The body 6 and the rod 10 each have a cup 14 which compresses the spring 2 against each other when the wheel mounts over a bump in the road, and which then extends. There is generally slight or no braking of the shock absorber 4 during the compression movement, and significant braking during the extension to ensure road holding.

[0031] An energy recovery subassembly comprises a cylindrical pot 20 having two superimposed parts 30, 32, arranged parallel to the axis of the shock absorber 4 near the spring 2, axially comprising on each side an arm of fixing 22, 26 having an axial part starting from this pot, then after a right-angle bend a transverse part ending with a clamping ring 24 fixed for the upper arm 22 on the shock absorber rod 10 and for the lower arm 26 on the shock absorber body 6.

[0032] An electrical cable 28 is inserted into the vertical part of the lower fixing arm 26 to run from the pot 20 to an energy storage device in the vehicle, comprising a means for regulating the received current.

[0033] The movements of the suspension during the rolling of the vehicle are transmitted via the shock absorber 4 and the fixing arms 22, 26 to the two parts 30, 32 of the cylindrical pot 20 which slide between them with an internal guide along the axis of this pot.

[0034] The upper part of the pot 30 includes a cylinder comprising an axially sliding piston, actuated by the relative movements of the two parts 30, 32. The lower part of the pot 32 includes a turbine receiving the air flow from the piston, which drives an integrated electric generator delivering, via the cable 28, a current to an energy storage device.

[0035] In particular the energy storage device can be the low voltage battery of the on-board network, which allows it to be recharged without taking energy from the vehicle's engine.

[0036] Figure 4 shows, in the upper part of the body 30, the piston 52 connected to the lower part of the pot 32 by an axial rod 54, separating a first upper chamber 50 from a second lower chamber 40, comprising an inlet non-return valve 42 allowing free passage from this upper chamber to this lower chamber. The lower chamber 40 has an outlet orifice equipped with an outlet non-return valve 44, delivering air to a turbine 48 disposed in the lower part of the pot 32. After the turbine 48, a return pipe 62 directs the air to the upper chamber 50.

[0037] An electric generator 60 has a common rotation shaft 46 with the turbine 48, to receive the mechanical power of this turbine transformed into an electric current sent on the cable 28.

[0038] During a compression of the suspension, the upper chamber 50 empties, freely transmitting air to the lower chamber 40 through the inlet check valve 42 of the piston 52. This compression is not braked, which is also generally the case with the hydraulic shock absorber 4.

[0039] During suspension expansion, the lower chamber 40 empties, compressing the air that feeds the turbine 48, driving the generator 60 via the outlet check valve 44, and then, after expansion, returns with low pressure to the chamber superior 50 by the return pipe 62. This slows the rebound movement of the suspension by adding a braking force to that of the shock absorber 4.

[0040] Alternatively, a bridge of non-return valves can be provided to straighten the airflow for suspension movement in both directions, allowing the turbine 48 to be supplied with both expansion and compression movements. In particular, air passages can be calibrated to obtain differentiated braking for movements in the two directions.

[0041] On some vehicles, the hydraulic shock absorber 4 can also be removed to obtain damping of movements solely with the recovery device, which then delivers the maximum energy.

Claims

Demands

1. Motor vehicle suspension system comprising an energy recovery device including a fixed part (30) linked to the chassis of the vehicle and a moving part (32) linked to a suspension element of a wheel of the vehicle, which generates an electric current during the movements between these two parts (30, 32), characterized in that the energy recovery device forms an independent subassembly (20) comprising a cylinder with a piston (52) displaced by the movements between the two parts (30, 32), separating two chambers (40, 50), a turbine (48) supplied by the air compressed by the piston (52), and an electric generator (60) driven by this turbine (48).

2. Suspension system according to claim 1, characterized in that it comprises a first check valve (44) which supplies the turbine (48) from a second chamber of the cylinder (40).

3. Suspension system according to claim 2, characterized in that it comprises a return pipe (62) which connects the outlet of the turbine (48) to a first chamber of the cylinder (50) opposite the second chamber (40), and comprises a second check valve (42) which allows passage from the first chamber (50) to the second chamber (40).

4. Suspension system according to any one of the preceding claims, characterized in that it comprises a set of check valves straightening the airflow to supply the turbine (48) from the two chambers (40, 50) for suspension movements in both directions.

5. Suspension system according to any one of the preceding claims, characterized in that the turbine (48) and the electric generator (60) are mounted on the same rotating shaft (46).

6. Suspension system according to any one of the preceding claims, characterized in that the two parts (30, 32) of the energy recovery device are connected to the two moving elements of a hydraulic damper (4).

7. Suspension system according to claim 6, characterized in that the energy recovery device forms a cylindrical pot (20) which is fixed parallel to the shock absorber (4) by two arms (22, 26) each connected to one side of this shock absorber (4).

8. Motor vehicle comprising wheel suspensions, characterized in that it comprises a suspension system according to any one of the preceding claims, which is disposed on each wheel of a wheel assembly.

9. Motor vehicle according to claim 8, characterized in that it comprises energy recovery devices which recharge the battery of the on-board network.

10. Motor vehicle according to claim 9, characterized in that the energy recovery devices are fixed on the two shock absorbers (4) of the same wheel assembly.

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