GB2273473A - System for vehicle suspension control and/or regulation - Google Patents

System for vehicle suspension control and/or regulation Download PDF

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Publication number
GB2273473A
GB2273473A GB9324291A GB9324291A GB2273473A GB 2273473 A GB2273473 A GB 2273473A GB 9324291 A GB9324291 A GB 9324291A GB 9324291 A GB9324291 A GB 9324291A GB 2273473 A GB2273473 A GB 2273473A
Authority
GB
United Kingdom
Prior art keywords
vehicle
changes
limiting means
travel
threshold value
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB9324291A
Other versions
GB9324291D0 (en
Inventor
Andrew-William Kingston
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of GB9324291D0 publication Critical patent/GB9324291D0/en
Publication of GB2273473A publication Critical patent/GB2273473A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60GVEHICLE SUSPENSION ARRANGEMENTS
    • B60G17/00Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load
    • B60G17/015Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load the regulating means comprising electric or electronic elements
    • B60G17/018Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load the regulating means comprising electric or electronic elements characterised by the use of a specific signal treatment or control method
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60GVEHICLE SUSPENSION ARRANGEMENTS
    • B60G2400/00Indexing codes relating to detected, measured or calculated conditions or factors
    • B60G2400/10Acceleration; Deceleration
    • B60G2400/102Acceleration; Deceleration vertical
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60GVEHICLE SUSPENSION ARRANGEMENTS
    • B60G2400/00Indexing codes relating to detected, measured or calculated conditions or factors
    • B60G2400/20Speed
    • B60G2400/204Vehicle speed
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60GVEHICLE SUSPENSION ARRANGEMENTS
    • B60G2400/00Indexing codes relating to detected, measured or calculated conditions or factors
    • B60G2400/20Speed
    • B60G2400/206Body oscillation speed; Body vibration frequency
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60GVEHICLE SUSPENSION ARRANGEMENTS
    • B60G2400/00Indexing codes relating to detected, measured or calculated conditions or factors
    • B60G2400/20Speed
    • B60G2400/208Speed of wheel rotation
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60GVEHICLE SUSPENSION ARRANGEMENTS
    • B60G2400/00Indexing codes relating to detected, measured or calculated conditions or factors
    • B60G2400/25Stroke; Height; Displacement
    • B60G2400/252Stroke; Height; Displacement vertical
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60GVEHICLE SUSPENSION ARRANGEMENTS
    • B60G2400/00Indexing codes relating to detected, measured or calculated conditions or factors
    • B60G2400/40Steering conditions
    • B60G2400/41Steering angle
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60GVEHICLE SUSPENSION ARRANGEMENTS
    • B60G2400/00Indexing codes relating to detected, measured or calculated conditions or factors
    • B60G2400/60Load
    • B60G2400/61Load distribution
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60GVEHICLE SUSPENSION ARRANGEMENTS
    • B60G2400/00Indexing codes relating to detected, measured or calculated conditions or factors
    • B60G2400/90Other conditions or factors
    • B60G2400/91Frequency
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60GVEHICLE SUSPENSION ARRANGEMENTS
    • B60G2500/00Indexing codes relating to the regulated action or device
    • B60G2500/10Damping action or damper
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60GVEHICLE SUSPENSION ARRANGEMENTS
    • B60G2600/00Indexing codes relating to particular elements, systems or processes used on suspension systems or suspension control systems
    • B60G2600/02Retarders, delaying means, dead zones, threshold values, cut-off frequency, timer interruption

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Vehicle Body Suspensions (AREA)

Description

2273473 SYSTEM FOR VEHICLE SUSPENSION CONTROL AND/OR REGULATION The
present invention relates to a system for at least one of control and regulation of a vehicle suspension.
An efficient suspension system between the wheel units and the vehicle structure is essential for refinement of the chassis of a motor vehicle In conventional suspension systems designed to be passive, the springing and/or damping characteristics are fixedly set as a compromise between travel comfort and travel safety.
Thereagainst, in a fully active system desired forces can be exerted between the wheels and the vehicle structure. In the case of a semi-active system, the suspension system in general consists of a spring arrangement which has a fixed spring characteristic and is connected in parallel with damping equipment with an adjustable damping characteristic. Such a shock absorber with an adjustable damping characteristic can be realised, for example, in such a manner that the shock absorber piston is equipped with a throttle valve having a variable throughflow cross-section.
An efficient method for the control or regulation of an adjustable suspension system is of great significance. For such control or regulation, switching signals for the adjustable suspension systems are generally supplied on the basis of sensor signal data giving information about the state of travel of the vehicle.
2 Such a chassis-regulating system is described in the SAE Article "Modular concept for suspension controP' by Decker, Schramm and Kallenbach, SAE 905124.
There remains scope, however, for further improvement in the operation of adjustable suspension systems.
According to the present invention there is provided a system for at least one of control and regulation of a vehicle suspension, comprising force-exerting actuators positionable between the vehicle structure and vehicle wheels and responsive to signals to cause the vehicle suspension to be influenced in dependence on the state of travel of the vehicle and limiting means to limit temporal changes in the signals.
Such a system serves for the regulation and/or control of a regulable and/or controllable suspension of a motor vehicle, by way of actuators which are arranged between the vehicle structure and the wheels and which are acted on by signals for the exertion of forces between the vehicle structure and the wheels in dependence on the state of travel. The limiting means limits the temporal changes of these signals, whereby the temporal changes of the forces to 'be exerted between the vehicle structure and the wheels are limited.
Advantageously, high-frequency peaks in the changes in force are inhibited. This improves travel comfort, reduces shocks and jolts perceivable in the vehicle and, on the case of use of adjustable shock absorbers, reduces switching noises without impairing the vehicle behaviour or travel comfort. Moreover, a reduction in costs may be possible in the design of the system components, since lower ds are placed on dynamic behaviour of the components (shock absorbers, sensors, electronic control device) in the system.
In an advantageous refinement of the system the limitations are carried out differently by the limiting means in accordance with the sign of the temporal changes of the signals or the forces to be exerted. The switchings of the actuators, thus the changes in force, which adjust the suspension system in the direction "hard" in that case are advantageously limited less than the changes in force which adjust the suspension system in the direction "sofC. It can thus be provided that changes in force which are effected in the direction of travel safety are limited less than those in the direction of travel comfort. This has the advantage that the system operates with a bias towards safety of travel.
In a further advantageous refinement, the limitations are carried out in dependence on the detected state of the travel.
Thus, the safety-oriented temporal force changes can be limited far less in the case of travel states critical for travel safety (for example, high longitudinal and/or transverse accelerations of the vehicle, violent steering movements) than the temporal changes oriented towards travel comfort. For this purpose, comparison means, by which the temporal changes of the force to be exerted are compared with at least one threshold value, can be provided for the limitation.
In a preferred embodiment it is provided that the temporal changes are camared with a first threshold in the presence of a positive force gradient and the temporal changes are compared with a second threshold in the presence of a negative force gradient, wherein the first threshold is chosen to be greater than the second 4 threshold. The temporal changes in the forces to be exerted are then limited if one of the two thresholds is exceeded. The threshold values can be fixed values, and/or can be dependent on magnitudes influencing the state of travel, such as longitudinal speed of the vehicle and/or longitudinal andlor transverse acceleration of the vehicle and/or steering angle and/or wheel speed and/or magnitudes derived therefrom. Thus, the temporal changes in the signals or the forces to be exerted can be limited less in situations critical for the travel safety than in situations not critical for the travel safety. If so desired no limitation.at all can take place in situations critical for travel safety.
In the case of semi-active suspension, the actuators can be shock absorbers which are adjustable in their damping behaviour for the exertion of controllable forces between the vehicle structure and the wheels. In the case of shock absorbers, noticeable switching noises can arise in the case of large changes in force.
From the aspect of travel safety, the changes in force for which the damping characteristics of the shock absorbers are set to be harder can be limited less than the changes in force for which the damping characteristics of the shock absorbers are set to be softer.
An embodiment of the present invention will now be more particularly described with reference to the accompanying drawings, in which:
Fig. 1 is a block schematic diagram of a system embodying the invention; Figs. 2a and 2b are parts of a flow chart illustrating stages of operation of limiting means in the system of Fig. 1; and Fig. 3 is a diagram showing the temporal courses 5 of signals for the switching of a shock absorber by way of a system embodying the invention and a prior art system.
Referring now to the drawings there is shown in Fig. 1 a system for controlling or regulating a motor vehicle suspension, the system comprising sensors S101, S102, etc., which supply input signals for processing means 11 which processes these input signals into shock absorber force target signals Fdij.' The index i denotes whether the suspension unit is at the front (i = v) or rear (i = h) of the vehicle and the index j whether the suspension unit is at the righthand 0 = r) or lefthand (j = 1) side of the vehicle. The designation F thus signifies the shock absorber target force for the front righthand suspension unit. The target forces Fdij are fed to means 12 for limitation of the temporal changes in such forces.
Switching signals Fij for actuators 13ij, in particular the shock absorbers are present at the output of the means 12. In addition, a signal S dependent on the state of travel can be fed to the means 12 for limitation of the temporal changes in force.
The control target forces for the actuators are computed in the means 11 in dependence on the state of travel ascertained by the sensors. For this purpose, the relative movements between the vehicle structure and the wheels, and/or movements of the structure in the form of structure acceleration and/or the instantaneous steering angle and/or the instantaneous wheel speeds are detected by, for example, sensors. From these data, switching signals for the actuators can now be computed in the means 11 in a manner known from the state of the art, for example, by the so-called sky-hook regulating principle in which forces proportional to the sensed absolute structure speed are exerted by the suspension systems.
There is thus obtained inertia] damping of the structure movements.
In addition, it is knom to damp the wheel movements in order to counteract the dynamic wheel load fluctuations. Whilst the quietening of the vehicle structure has primarily the consequence of advantages in travel comfort, an increase in the travel safety Js also achieved by a minimisation of the dynamic wheel load f 1 uctuati ons.
In this embodiment, the actuators are constructed as shock absorbers which are adjustable in their damping behaviour.
The detailed function of the means 12 for limitation of the temporal changes in force is described in the following with reference to the flow diagram of the Figs.'2a, and 2b.
In the Fig. 2a, the actual value of the force Fdijnew (shock absorber target force) to be exerted and the previously ascertained value Hijold for the shock absorber force are read in in a step 202 after a start step 201. In a step 203, the new value Fdijnew is compared with the previously ascertained value Hijold. If the new value to be exerted is higher than the previously ascertained value, a positive force gradient thus being present, the magnitude of the change of the target forces is compared with a threshold value LIMIT 1 in a step 204 as shown in Fig. 2b. In the case of a negative force gradient, thus when the actual new value Fdijnew is lower than the previously ascertained value Hijold, the magnitude of the difference is compared with a second threshold value LIMIT 2 in a step 205.
If it is established on the steps 204 and 205 that the shock absorber force changes in the means 11 are smaller than the respective threshold values LIMIT 1 and LIMIT 2, then the new value Fd ijnew is passed on in the step 206 to the respective shock absorber 13ij and a corresponding force is exerted between the respective wheel and the vehicle structure. If it is ascertained-in the steps 204 or 205 that the temporal changes in force are greater than the respective threshold values, then the shock absorber target force Fij = Hijold + LIMIT 1 is set in the case of a positive force gradient in a step 207 and the shock absorber target force Fij Hijold - LIMIT 2 is set in the case of a negative force gradient in a step 208. The force value Fdijnew ascertained as actual in step 202 is then set as previously ascertained Hijold in the step 209 in order, after an end step 210, to be entered as previously ascertained value in step 202 of the subsequent program run.
The threshold values LIMIT 1 and LIMIT 2 can either assume fixed values or be chosen in dependence on the detected state of travel. For this purpose, it is indicated in the Fig. 1 that the travel state signal S is to be fed to the means 12. With advantage, the threshold values LIMIT 1 and LIMIT 2 are respectively dependent on magnitudes which influence the state of travel. Such magnitudes are, for example, the longitudinal speed of the vheicle, the steering angle, the rotational wheel speeds or magnitudes derived therefrom. For preference, the first threshold LIMIT 1 is chosen to be greater than the second threshold LIMIT 2. This has the consequence that the positive changes in force, which generally signify adjustments oriented towards travel safety, are limited less than negative changes in force, in which the suspension systems are adjusted to be "softer".
The effect of the limitation in change of force is to be seen in Fig. 3. For this purpose, the unlimited shock absorber target force Fdii (thinly drawn line 1) and the limited shock absorber target force Fij (thickly drawn line 2) are entered as a function of time t. It can be clearly seen that far greater jumps in force arise without the force change limitation (line 1) than with the force change limitation (line 2).
t.

Claims (14)

- 9 CLAIMS
1 A system for at least one of control and regulation of a vehicle suspension, comprising force-exerting actuators positionable between the vehicle structure and vehicle wheels and responsive to signals to cause the vehicle suspension to be influenced in dependence on the state of travel of the vehicle and limiting means to limit temporal changes in the signals.
2. A system as claimed in claim 1, the limiting means being arranged to vary the limitation of such changes in dependence on whether the changes are positive or negative.
3. A system as claimed in claim 1 or claim 2, the limiting means being arranged to effect limitation of such changes in dependence on the instantaneous state of travel of the vehicle.
4. A system as claimed in any one of the preceding claims, the limiting means being arranged to compare such changes with at least one threshold value and to carry out limitation of the changes in dependence on the comparison result.
5. A system as claimed in any one of the preceding claims, the limiting means being arranged to impose a lesser limitation on temporal changes in signals which cause the actuators to exert greater forces representing a positive force gradient than on temporal changes in signals which cause the actuators to exert smaller forces representing a negative force gradient.
-
6. A system as claimed in claim 5, the limiting means being arranged to compare such changes with a first threshold value in the presence of a positive force gradient and with a second threshold value lower than the first threshold value in the presence of a negative force gradient and to carry out limitation of the changes if either threshold value is exceeded.
7. A system as claimed in claim 4 or claim 6, wherein the or each threshold value is a fixed value.
8. A system as claimed in claim 4 or claim 6, wherein the or each threshold value is dependent on at least one- magnitude related to the state of travel of the vehicle.
9. A system as claimed in claim 8, wherein the magnitude or magnitudes is or are selected from the group consisting of longitudinal speed of the vehicle, longitudinal acceleration of the vehicle, transverse acceleration of the vehicle, angle of the vehicle steering, rotational speed of the vehicle wheels and magnitudes derived therefrom.
10. A system as claimed in any one of the preceding claims, the limiting means being arranged to limit such changes less in circumstances predetermined to be critical for the travel safety of the vehicle than in circumstances predetermined not to be critical for the travel safety of the vehicle.
11. A system as claimed in any one of the foregoing claims, wherein the actuators comprise shock absorbers with adjustable damping characteristics.
12. A system as claimed in claim 11, the limiting means being arranged to so limit such changes that a lesser limitation is effected in the case of resetting the damping characteristics to harder than in the case of resetting the damping characteristics to softer.
13. A system substantially as hereinbefore described with reference to the accompanying drawings.
14. A road vehicle provided with a system as claimed in anythe of the preceding claims.
GB9324291A 1992-12-03 1993-11-25 System for vehicle suspension control and/or regulation Withdrawn GB2273473A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19924240614 DE4240614A1 (en) 1992-12-03 1992-12-03 System for regulating and / or controlling an adjustable and / or controllable undercarriage

Publications (2)

Publication Number Publication Date
GB9324291D0 GB9324291D0 (en) 1994-01-12
GB2273473A true GB2273473A (en) 1994-06-22

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GB9324291A Withdrawn GB2273473A (en) 1992-12-03 1993-11-25 System for vehicle suspension control and/or regulation

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JP (1) JPH06206417A (en)
DE (1) DE4240614A1 (en)
GB (1) GB2273473A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1256467A3 (en) * 2001-05-09 2004-12-15 Continental Aktiengesellschaft Method for controlling the flow of electrically controlled dampers
US6871731B2 (en) * 2002-01-29 2005-03-29 Continental Aktiengesellschaft Adjustable shock absorber for a motor vehicle

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10112159A1 (en) * 2001-03-14 2002-09-19 Wabco Gmbh & Co Ohg Method and device for determining the driving condition of vehicles in the event of failure or lack of a speed sensor

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0221486A2 (en) * 1985-10-26 1987-05-13 Toyota Jidosha Kabushiki Kaisha Shock absorber controller
EP0246772A1 (en) * 1986-05-02 1987-11-25 Rover Group Limited A suspension system for a motor vehicle
GB2214473A (en) * 1987-09-04 1989-09-06 Mitsubishi Motors Corp Active vehicle suspension apparatus
GB2220176A (en) * 1988-06-16 1990-01-04 Fuji Heavy Ind Ltd Control device for a motor vehicle active fluid suspension system
GB2220624A (en) * 1988-05-31 1990-01-17 Atsugi Motor Parts Co Ltd Control of the damping in a hydraulic shock absorber
GB2255752A (en) * 1991-05-11 1992-11-18 Bosch Gmbh Robert System for controlling or regulating vehicle suspension.

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0221486A2 (en) * 1985-10-26 1987-05-13 Toyota Jidosha Kabushiki Kaisha Shock absorber controller
EP0246772A1 (en) * 1986-05-02 1987-11-25 Rover Group Limited A suspension system for a motor vehicle
GB2214473A (en) * 1987-09-04 1989-09-06 Mitsubishi Motors Corp Active vehicle suspension apparatus
GB2220624A (en) * 1988-05-31 1990-01-17 Atsugi Motor Parts Co Ltd Control of the damping in a hydraulic shock absorber
GB2220176A (en) * 1988-06-16 1990-01-04 Fuji Heavy Ind Ltd Control device for a motor vehicle active fluid suspension system
GB2255752A (en) * 1991-05-11 1992-11-18 Bosch Gmbh Robert System for controlling or regulating vehicle suspension.

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1256467A3 (en) * 2001-05-09 2004-12-15 Continental Aktiengesellschaft Method for controlling the flow of electrically controlled dampers
US6871731B2 (en) * 2002-01-29 2005-03-29 Continental Aktiengesellschaft Adjustable shock absorber for a motor vehicle

Also Published As

Publication number Publication date
GB9324291D0 (en) 1994-01-12
DE4240614A1 (en) 1994-06-09
JPH06206417A (en) 1994-07-26

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)