WO2002008001A1

WO2002008001A1 - Device for regulating the movements of the superstructure of a motor vehicle

Info

Publication number: WO2002008001A1
Application number: PCT/EP2001/008495
Authority: WO
Inventors: Peter Rieth; Stefan Drumm; Johann Jungbecker
Original assignee: Continental Teves Ag & Co. Ohg
Priority date: 2000-07-26
Filing date: 2001-07-23
Publication date: 2002-01-31

Abstract

The invention relates to a device for regulating the movements of the superstructure (12) of a motor vehicle, whereby said superstructure (12) is supported directly or indirectly by a serially connected active actuating member (1) and a supporting spring (21) on at least a wheel axle. The actuating member (1) is formed from an electromechanical drive.

Description

Device for regulating movements of the body of motor vehicles

The invention relates to a device for avoiding undesirable movements in the construction of motor vehicles. The standard here are springs arranged between the wheel axle and the body of the motor vehicle, which oppose the movement of the wheels in relation to the body with a growing force. Faster vibrations are eliminated or at least greatly reduced by dampers coupled to the springs.

Systems for changing the height or the distance of the superstructure above the road are also in this context. For this purpose, it is known to generally integrate the level control into the shock absorber in vehicles with steel springs. The shock absorber can also be pumped up automatically and caused by the vertical vehicle movements up to the desired control height in the vehicle body. In vehicles with air springs, the height can also be regulated in that the air springs receive a larger amount of pressure medium when they are loaded via corresponding external sensors. Furthermore, it is also known for vehicles with a hydropneumatic suspension to control the height with the aid of a hydraulic actuator. However, all these known systems serve exclusively to regulate the height of the body, ie the height of the vehicle body above the ground. The distance between the superstructure and the roadway changes with a change in the payload, so that the known systems mentioned are designed to carry out the corresponding control process extremely slowly, with a corresponding control process can last from several seconds to minutes. It is impossible with these known systems to compensate for dynamic load fluctuations, for example as an effect on the current driving state or on fast-moving movements of the bodywork (for example, vibrations that build up).

Even if you wanted to design the known systems for fast control processes, the energy and power required for this would hardly be available. In theory, fully active hydraulic suspension systems enable optimal suspension control with regard to driving comfort and handling of the vehicle. However, they prove to be unrealistic from a cost point of view and even if they are

Performance savings Additional components are provided, very high performance requirements.

From DEAS 2604809 it is known for an adjustable suspension system for vehicles to harden the spring stiffness, which serves to improve the running stability or controllability of the vehicle.

Furthermore, reference should also be made to DEOS 3738284, which describes an active chassis control for motor vehicles, which is based on known level controls, and a first active actuator for which, depending on the relative spring deflection, is applied

Level control system and a second active actuator in the form of an active or a semi-active damper between the wheel suspension and vehicle body. On such a system has a very high energy requirement.

Finally, it has become known from EPPS 444278 to connect a spring element with an actuator in series to regulate the movement of a vehicle body, this series connection also having a supporting spring connected in parallel between the vehicle body and the wheel axle.

The invention is therefore based on a device of the type resulting from the preamble of claim 1. The object of the invention is to provide a simply constructed and effective device by means of which a fast active regulation of the movements of the vehicle body is possible to increase the vehicle stability. The object of the invention is also to provide a shock absorber which is particularly suitable for simple and quick regulation.

The object is achieved on the one hand by the combination of features resulting from the characterizing part of claim 1. In principle, the invention therefore consists in using an electromechanical actuator for active control of the movements of the vehicle body, which can carry out the necessary mechanical adjustment movements very simply and quickly, such an actuator being comparatively inexpensive. A hydraulic actuator with complex lines, accumulators and pumps can thus be dispensed with.

The invention creates a dynamically active chassis control in a surprisingly simple manner, which without hydraulic pressure supply needs. Based on the invention can also be achieved that the energy consumption is minimized and comfort is increased. In the system according to the invention, an electromechanical drive forms an active spring damper system, which is with its drive and, as additional units to be accommodated in the vehicle, only requires an electrical power supply and an electrical control. The hydraulically independent damper can be retained.

A particularly simple structure for the actuator results from the combination of features listed in claim 2. A comparatively inexpensive electric motor is inserted into the area of the body, which is supported on a wheel axle by the device according to the invention. This electric motor drives a threaded spindle, on the thread of which a non-rotatably arranged and axially movable threaded screw is seated. If the spindle rotates, the screw moves up and down, changing the height of the body. The motor and the spindle driven by it react very quickly to corresponding actuation signals, so that the arrangement described is very well suited for dynamic control of the movements of the vehicle body. However, if the vehicle has a hydraulic unit, for example for power steering, it may be advisable to choose a hydraulic drive to drive the actuator.

In order to save energy in the movement of the body by the electric motor, the combination of features according to claim 3 is recommended in a further development of the invention Relief spring, which is preferably set such that it keeps the thread largely free of contact forces due to the structure of the vehicle with its windings not standing on the block, it is possible that only the dynamic movements of the structure need be effected by the actuator. The thread is largely spared from the support forces of the structure. However, it is necessary that the actuator must work against the force of the relief spring in the case of downward movements of the body. The spring should be set so that the force to be exerted by the motor is the same in both directions.

Active chassis control systems are intended to reduce or completely compensate pitch and roll movements of the vehicle body by means of control interventions. To do this, each of the four actuators must be able to raise its vehicle corner. The lifting work required for this is the integral of (adjustment force x adjustment path). If the actuator is relieved of the purely static force component, only a fraction of the energy has to be used during control interventions. Therefore, as shown in Figure 2, it is proposed according to claim 3 to use parallel to the actuators relief springs (6) which are statically matched so that the actuators (1) are relieved when the vehicle is at rest.

A further improvement can thus be achieved by using the features according to claim 4, where the use of gas springs for the suspension spring or the relief spring is proposed. Gas springs offer compared to steel springs a higher suspension comfort. In addition, static deflection, for example caused by an increase in weight as a result of the load, can be compensated for by supplying air. The special advantage of gas springs steel springs is that the own frequency of the FederMasseSyste s is almost independent of the payload.

The system shown in FIG. 3 thus has gas springs (7) which offer greater suspension comfort than steel springs. In addition, a static deflection, for example caused by an increase in weight as a result of an additional load, can be compensated for by the supply of air (level control). The special advantage of gas springs over steel springs is that the natural frequency of the spring-mass system is almost independent of the payload.

When representing a regulation of the vertical dynamics using air springs, there is the possibility of regulating the heights of the air columns of an air spring system not only quasi-statically in the sense of level regulation, but also dynamically. However, such a procedure has hitherto proven to be of little practicality since the speed of sound in air forms a physical limit for the flow speed in the pneumatic feed lines that is required for fast control processes with a high amplitude. In order not to come close to this limit, unacceptably large supply cross-sections would have to be chosen.

It is therefore proposed that the upper end of the gas springs (7) For example, as a plate (9) designed to be adjustable by an actuator (1), as shown in FIG. 4. It is advantageous to use an electromechanical drive (1), but if a hydraulic unit, for example for a power steering, is already present in the vehicle, the hydraulic drive may also be an inexpensive variant. In any case, it is advantageous to use the actuator relief spring (6 or 8) to reduce energy consumption. All advantages are combined in a system that uses both gas suspension springs (7) and gas actuator relief springs (8) (FIG. 4), with both gas springs either being able to supply or discharge air independently of one another or one of these springs, the other gas spring can be connected to this via an electrically controllable pneumatic valve. The electromechanical drive (1) can preferably be accommodated within the actuator relief gas spring 8.

To regulate a chassis equipped with the struts according to the invention, at least the sensor information about the spring deflection is necessary. For this purpose, the struts according to the invention are equipped with displacement sensors (10). Furthermore, sensors can also be provided for the actuator paths. Both sensor systems can be combined in the spring strut to form a sensor unit. In addition, the pneumatic pressures in the gas springs can also be sensed to determine the exact system status. In an advantageous development of the invention, the use of the features listed in claims 9 and 10 is therefore recommended The system presented here combines the advantages of the sophisticated pneumatic system for active chassis level control and the electromechanical actuators optimized in terms of efficiency, design and power density to form a fully active chassis control system with minimal energy consumption. Electrical energy is only used in a medium dynamic range. Very fast compression movements are absorbed by the conventional hydraulic damper, slow movements by a pneumatic level control system. The middle area, which is covered by the electromechanical actuators, primarily concerns the control of roll, pitch and lifting movements of the vehicle, such as occur when cornering, accelerating and braking and when driving over bumps.

Previous approaches to active chassis control have regularly failed due to the excessive energy consumption, since attempts have often been made to cover an excessively large dynamic range with energy-consuming actuators. The proposed system, on the other hand, leaves the area of high dynamics, in which any active system would be energetically overwhelmed, to a passive damper and the area of low dynamics of the level control, which, once set, does not require any further energy supply. The energy requirement in the medium dynamic range, in which active regulation is carried out, is minimized by using the (preferably pneumatically adjustable) actuator relief springs. The optimal suspension comfort known from dynamic passive gas spring systems is fully retained even with active chassis control. To display an active chassis control with minimal energy consumption, starting from a vehicle with a pneumatically level-adjustable chassis, only the spring struts have to be exchanged for the additionally electrically adjustable ones presented here, sensors and control electronics have to be added. No other units are to be accommodated in the vehicle chassis. The system can therefore be retrofitted into a vehicle without major problems.

The solution to the problem of the shock absorber according to the invention is the combination of features set out in claim 11. Advantageous further developments in the invention result from subclaims 11 to 27.

Embodiments of the invention are explained below with reference to the drawing. It shows:

Fig. 1 a device provided with a steel spring supporting spring device or the strut belonging to this device

Fig. 2 shows the device or strut of FIG. 1, in which a relief spring was also inserted

Fig. 3 shows a device or strut corresponding to Fig. 1, in which the steel spring has been replaced by a gas spring and

Fig. 4 shows the embodiment of FIG. 2, in which both the suspension spring and the relief spring are formed by gas springs.

Fig. 1 shows a support 12 on which the structure of the vehicle in Fig. 1 can be directed downward. The Pad 12 sits on rubber buffer 13 on a motor housing 14 which receives an electric motor 15 as electromechanical drive 1. The motor is anchored with its poles 16 in the motor housing 14. The rotor of the motor is optionally connected in one piece to a threaded spindle 17, on the ball thread 18 of which a threaded screw 19 is non-rotatably but axially movable. If the threaded spindle 17 is rotated in one of two directions by the electric motor, the threaded screw 19 moves up or down. Balls are inserted between the thread of the threaded screw and the threaded spindle, which together produce a ball gear. If, for example, the threaded spindle 17 is rotated in a first direction of rotation, the threaded screw 19 moves upward and thus raises the support 12. When the direction of rotation of the threaded spindle 17 is reversed, the support is lowered. The threaded screw 19 is held in a connecting sleeve 20, the upper edge of which forms a plate 9 on which a suspension spring 21 is supported with its upper end in FIG. 1. The electromechanical drive 1 and the suspension spring 21 are thus connected in series. With its lower end, the suspension spring 21 is seated on a housing 22 of a damper 23, wherein the housing 22 of the damper can consist of several parts. The lower end 24 of the damper 23 is at least indirectly connected to a wheel axle, which is not shown in FIG. 1. The damper 23 has, as usual, a piston 25 which is guided sealingly on the inner surface of the housing 22. As usual, the damper has the task of compensating for rapid vibrations of the wheel compared to the structure of the vehicle. The piston rod 26 of the damper 23 is connected to the connecting sleeve 20 so that the vibrations of the suspension spring 21 against the connecting sleeve 20 are damped by the damper 23. The motor housing 14 and the housing 22 of the damper 23 are provided with a first diaphragm 27 and a second diaphragm 28 which interlock in a telescopic manner.

In order to be able to regulate the movements of the structure and thus the support 12, a sensor must be inserted which can measure such movements. A first sensor 30 is therefore inserted at the bottom of the connecting sleeve 20 and is able to measure the movement of the connecting sleeve 20 and thus of the threaded screw 19 relative to the support 12. For this purpose, a pin 29 anchored relative to the support 12, which transmits the movement of the support 12 relative to the connecting sleeve 20. This movement can be measured by the first sensor 30. Of course, within the scope of the invention, the first sensor or further sensors can be attached to other suitable locations on the device.

In the embodiment of Fig. 1, it is disadvantageous that the entire load of the body of the motor vehicle must be absorbed by the ball gear with the threaded screw 19 and the threaded spindle 17. The loads on the transmission are therefore considerable and the resulting friction must be overcome by a corresponding expenditure of energy. In addition, the control works asymmetrically, since gravity acts as a support and counteracts the drive in the opposite direction. In Fig. 2, therefore, a relief spring 6 is inserted, which frees the ball gear from the load of gravity, so that only the acceleration of the body has to be transmitted in both directions via this gear. This gives considerable savings in energy, since the relief spring 6 is connected in parallel with the transmission and is otherwise in series with the suspension spring 21

The embodiment according to FIG. 3 is largely the same as that of FIG. 1, only that the suspension spring 21 has been replaced by a gas spring 7, which can also be used to regulate the level, that is to say the control of the height of the support 12 relative to the road. The advantages that can be achieved by using a gas spring have already been described in detail above.

In Fig. 4, both the suspension spring 21 and the relief spring 6 have been replaced by a gas spring 7 and 21, respectively. The two gas springs can be controlled and fed by a common source so that the suspension spring can be adjusted to a certain extent. The suspension spring 7 can also remain reversed by being filled up once and remaining in this state later. The gas spring 7 may further serve to change the height of the support 12 in greater extent to ^', to thereby control the level that is the distance between the support 12 and the road surface is obtained. The smaller vibrations of the support 12 can at least be compensated for by the second gas spring 8. If both springs are not activated, the gas springs can be made in one piece via a split bellows. However, it is also possible to fill the upper bellows belonging to the relief spring 6 once with gas and to actuate the gas spring 7 by means of a corresponding gas source for regulating the level.

Claims

claims

1. Device for controlling movements of the body (12) of motor vehicles, the body (12) being supported indirectly or directly on at least one wheel axle via a series circuit comprising an actuator (1) and a suspension spring (21), characterized in that the actuator (1) is an electromechanical drive.

2. Device according to claim 1, characterized in that the actuator (1) is provided with an electric motor (15), the pole windings of which are fixed relative to the structure (12) and the rotor of which drives a threaded spindle (17), by means of which the rotation of the The distance between a threaded screw (19) and the body (12) can be changed and the support spring (21) is supported at least indirectly on the threaded screw (19) with its end facing away from the wheel axle.

3. Apparatus according to claim 1 or 2, characterized in that the actuator (1), a relief spring (6) is connected in parallel, with one end at least indirectly on the structure

(12) facing end of the day spring (6) and with its other end at least indirectly supported on the structure (12).

4. Device according to one of the preceding claims, characterized in that the suspension spring (21) and / or the relief spring (6) is formed by a gas spring.

5. Device according to one of the preceding claims, characterized in that the gear screw (19) in connection with the spindle (17) forms a ball gear.

6. Device according to one of the preceding claims, characterized in that the relief spring (6) is selected in its rigidity such that it can bear the load exerted on it by the structure (12) without standing on the block.

7. Device according to one of the preceding claims, characterized in that a connecting sleeve (20) is provided on which both the support spring (21) and the relief spring (6) is supported and which also from the spindle (17) - on the threaded screw (19) absorbs the force exerted and transmits it to the suspension spring (21).

8. The device according to claim 7, characterized in that an extension of the connecting sleeve (20) is connected to a piston (25) which projects into a cylinder which is at least indirectly connected to the wheel axle and forms a damper (23) with the latter and at which the The support spring (21) is supported on the cylinder end facing away from the wheel axis.

9. Device according to one of the preceding claims, characterized in that a with the structure (12) facing the end of the suspension spring (21) connected to the first sensor (30) is provided which detects the movement of the Structure (12) facing the end of the suspension spring (21) with respect to the vehicle axle, the sensor (30) preferably being attached to the extension of the connecting sleeve (19).

10. Device according to one of the preceding claims, characterized in that a second sensor (31) is provided which receives the movement of the body relative to the vehicle axis, the sensor

(Clearly) is preferably attached to a rod (29), which has its first end connected to the structure (12) and projects into the cylinder and carries the sensor (31) there.

11. Suspension strut for motor vehicles, the suspension strut having a suspension spring, a damper and an actuator (1) with which the length of the suspension strut can be changed, characterized in that the actuator (1) has an electromechanical drive.

12. Strut for motor vehicles according to claim 11, characterized in that the electric drive motor of the electromechanical drive is attached directly to the strut.

13. Strut for motor vehicles according to claim 12, characterized in that the electric drive motor of the electromechanical drive is structurally integrated in the strut.

14. Strut for motor vehicles according to claim 11, 13 characterized in that the actuator (1) is arranged in series with the suspension spring.

15. A strut for motor vehicles according to claim 14, characterized in that the actuator (1) is connected to the upper, body-side end of the strut and the suspension spring to the lower, wheel-side end of the strut.

16. Shock absorber for motor vehicles according to claim 15, characterized in that the suspension spring is supported on the actuator (1) via a spring plate (20), the distance of the spring plate from the upper end of the spring strut being variable with the aid of the actuator.

17. Strut for motor vehicles according to one of claims to 16, characterized in that the damper is arranged parallel to the series connection of the suspension spring and actuator (1) between the upper and lower ends of the strut.

18. Strut for motor vehicles according to claim 17, characterized in that the axes of symmetry of the actuator (1) and damper coincide.

19. Strut for motor vehicles according to one of claims 11 to 18, characterized in that the actuator (1) is assigned a parallel relief spring (6).

20. Strut for motor vehicles according to claim 19, characterized characterized in that the relief spring (6) is designed such that it largely keeps the static portion of the strut load from the actuator (1).

21. Strut for motor vehicles according to one of claims 11 to 20, characterized in that the day spring (21) or the relief spring (6) or both springs are each formed by a gas spring, the gas quantities in the gas springs of the individual struts via corresponding connections and valves can also be changed while driving.

22. Strut for motor vehicles according to one of claims 11 to 21, characterized in that the actuator contains a ball screw.

23. Strut for motor vehicles according to claim 22, characterized in that the threaded spindle of the ball screw drive is rotated by the electric drive motor and the spindle nut is fastened to the spring plate (20).

24. Strut for motor vehicles according to one of claims 11 to 23, characterized in that a first sensor

(31) is provided, which detects the current length of the shock absorber or its spring deflection.

25. Strut for motor vehicles according to one of claims 11 to 24, characterized in that a second sensor

(30) is provided, which detects the travel of the actuator (1).

26. Strut for motor vehicles according to claim 25, characterized in that the second sensor (30) is formed by means which detect the rotation of the drive motor.

27. Strut for motor vehicles according to claim 24, 25 or 26, characterized in that at least one of the sensors (30, 31) is formed by a sensor element which is received by the hollow damper shaft and determines its path signal based on the position of a permanent magnet, the Magnetic field protrudes through the wall of the damper shaft into its hollow center,