WO2001000468A1

WO2001000468A1 - Integrated braking and suspension control systems for a vehicle

Info

Publication number: WO2001000468A1
Application number: PCT/US2000/017848
Authority: WO
Inventors: Richard Barron; Dinghai Pan
Original assignee: Kelsey-Hayes Company
Priority date: 1999-06-30
Filing date: 2000-06-28
Publication date: 2001-01-04
Also published as: AU5776300A

Abstract

A control system for controlling braking and suspension functions of a vehicle includes a braking algorithm (106). A first signal processor (104) receives input signals from at least one sensor (108, 112, 115, 117, 120) and transmits transfer signals to the braking algorithm. The control system also includes a suspension algorithm (134). A second signal processor (132) receives input signals from at least one sensor (135, 137, 139, 141, 143) and transmits transfer signals to the suspension algorithm (152). Transfer signals are generated by the braking algorithm and transmitted to the suspension algorithm. Transfer signals are generated by the braking algorithm and transmitted to the suspension algorithm. Transfer signals are generated by the suspension algorithm and transmitted to the braking algorithm. Output signals (126) are generated by the braking algorithm and transmitted to a hydraulic control unit (128) to control vehicular braking. Output signals (148) are generated by the suspension algorithm and transmitted to a suspension actuator (150) to control vehicular damping.

Description

TITLE INTEGRATED BRAKING AND SUSPENSION CONTROL SYSTEMS

FOR A VEHICLE

CROSS REFERENCE TO RELATED APPLICATION

This invention claims the benefit of U.S. patent application identified as Application Number 09/345,206, filed June 30, 1999.

BACKGROUND OF THE INVENTION This invention relates in general to electronically-controlled vehicular braking and suspension systems. In particular, this invention is concerned with vehicular control systems that integrate braking and suspension functions.

Electronically-controlled vehicular braking systems can include anti-lock braking (ABS), traction control (TC), and vehicle stability control (VSC) functions. In such braking systems, sensors deliver input signals to an electronic control unit (ECU). The ECU sends output signals to electrically activated devices to apply, hold, and dump (relieve) pressure at wheel brakes of a vehicle. Oftentimes, electrically activated valves and pumps are used to control fluid pressure at the wheel brakes. Such valves and pumps can be mounted in a hydraulic control unit (HCU). The valves can include two-state (on/off or off/on) solenoid valves and proportional valves

Electronically-controlled suspension systems can include semi-active suspension systems and active suspension systems to provide active damping for a vehicle. In such suspension systems, sensors deliver input signals to an electronic control unit (ECU). The ECU sends output signals to electrically activated devices to control the damping rate of the vehicle. Such devices include actuators to control fluid flow and pressure. Oftentimes, the actuators include electrically activated valves such as two-state solenoid valves and proportional valves.

SUMMARY OF THE INVENTION

This invention relates to electronically-controlled vehicular systems that integrate braking and suspension functions. Braking functions can include anti-lock braking, traction control, and vehicle stability control. Suspension functions can include active damping. An integrated control system according to this invention receives input signals, calculates a desired response with braking and suspension algorithms, and directs devices to perform the desired functions.

In a preferred embodiment, a control system for controlling braking and suspension functions of a vehicle includes a braking algorithm. A first signal processor receives input signals from at least one sensor and transmits transfer signals to the braking algorithm. The control system also includes a suspension algorithm. A second signal processor receives input signals from at least one sensor and transmits transfer signals to the suspension algorithm. Transfer signals are generated by the braking algorithm and transmitted to the suspension algorithm. Transfer signals are generated by the suspension algorithm and transmitted to the braking algorithm. Output signals are generated by the braking algorithm and transmitted to a hydraulic control unit to control vehicular braking. Output signals are generated by the suspension algorithm and transmitted to a suspension actuator to control vehicular damping. In other embodiments of an integrated control system, only the braking algorithm transfers signals to the suspension algorithm. In yet other embodiments, only the suspension algorithm transfers signals to the braking algorithm.

Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram of a first embodiment of an integrated vehicular control system according to the present invention illustrating input signals delivered to electronic control units, transfer of signals between the electronic control units, and output signals delivered from the electronic control units to electrically activated braking and suspension devices.

Fig. 2 is a schematic diagram of a second embodiment of an integrated vehicular control system according to the present invention for controlling braking and suspension devices wherein an anti-lock braking/traction control algorithm and a vehicular stability control algorithm are provided.

Fig. 3 is a schematic diagram of a third embodiment of an integrated vehicular control system according to the present invention for controlling braking and suspension devices wherein a single electronic control unit is utilized. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a vehicular control system according to the present invention is indicated generally at 100 in Fig. 1. The control system 100 is particularly adapted to control fluid pressure in an electronically-controlled vehicular braking system and an electronically-controlled vehicular suspension system. The braking system can include anti-lock braking, traction control, and vehicle stability control functions. The suspension system can include active damping functions.

The control system 100 includes a first electronic control unit (ECU) 102. The first ECU 102 includes a signal processor 104 and a braking algorithm 106.

Various sensors 108 strategically placed in a vehicle deliver input signals 110 to the signal processor 104. Specifically, a lateral acceleration sensor 112 delivers an input signal 114 to the signal processor 104. A longitudinal acceleration sensor 115 delivers an input signal 116 to the signal processor 104. A steering wheel sensor 117 delivers an input signal 118 to the signal processor 104. A yaw rate sensor 120 delivers an input signal 122 to the signal processor 104. Depending upon the braking functions of the braking system, some of the above-listed sensors and their associated input signals may be deleted and others may be added. For example, a braking system that provides only ABS and TC functions may not require some of the above-listed sensors.

The signal processor 104 delivers transfer signals 124 to the braking algorithm 106. The braking algorithm 106 delivers output signals 126 to a hydraulic control unit (HCU) 128. The HCU 128 can include electromechanical components such as solenoid and/or proportional valves and pumps (not illustrated). The HCU 128 is hydraulically connected to wheel brakes and a source of brake fluid, neither of which is illustrated.

The control system 100 also includes a second ECU 130. The second ECU 130 includes a signal processor 132 and a suspension algorithm 134. Various sensors 135 strategically placed in a vehicle deliver input signals 136 to the signal processor 132. Specifically, a suspension state sensor 137 delivers an input signal 138 to the signal processor 132. A suspension displacement sensor 139 delivers an input signal 140 to the signal processor 132. A relative velocity sensor 141 delivers an input signal 142 to the signal processor 132. An upsprung mass acceleration sensor 143 delivers an input signal 144 to the signal processor 132. Depending upon the performance requirements of suspension system, some of the above-listed sensors may be deleted and others may be included.

The second signal processor 132 delivers transfer signals 145 to the suspension algorithm 134. The first signal processor 104 delivers transfer signals 146 to the suspension algorithm 134. The suspension algorithm 134 delivers output signals 148 to suspension actuators 150, only one of which is illustrated. The actuators 150 are electrically controlled devices such as dampers that vary and control a damping rate of a vehicle. An actuator 150 can include electromechanical components such as solenoid and proportional valves. Information from the vehicular braking system can be shared with the vehicular suspension system. For example, ECU 102 can direct information to ECU 130. One example of transferred information from the braking system to the suspension system is the transfer signal 146 from signal processor 104 to suspension algorithm 134. A second example of transferred information from the braking system to the suspension system is indicated by transfer signal 152, wherein information from the braking algorithm 106 is directed to the suspension algorithm 134.

Information from the suspension system can also be shared with the braking system. For example, ECU 130 can direct information to ECU 102. One example of transferred information from the suspension system to the braking system is a transfer signal 154 to a load and load transfer detector 155. Another example is a transfer signal 156 to a turning detector 157. Yet another example is a transfer signal 158 for surface and mismatch tire detector 159.

The control system 100 can be configured in various manners to share information from ECU 102 to ECU 130, and vice versa. In one example, an ECU 102 for the braking system that receives inputs signals 114, 116, 1 18 and 122, for lateral acceleration, longitudinal acceleration, steering wheel angle, and yaw rate, respectively, can transfer these input signals to ECU 130 for the suspension system. The signal processor 104 of ECU 102 can send transfer signal 146 to the suspension algorithm 134.

In another example, if lateral acceleration and steering wheel angle signals 114 and 122 are not available to the braking system, a turning detector signal can be generated by ECU 130 and transmitted to ECU 102 to improve braking performance. If an electronically controlled suspension system is integrated with an electronically controlled ABS/TC braking system, turning of the vehicle can be detected by the suspension system, thereby generating a turning detector signal that is transmitted to a braking system that does not receive signals from lateral acceleration and steering wheel angle sensors. A turn detection signal to the braking system via ECU 102 can enhance braking performance, particularly during braking- in-turn and accelerating-in-turn. A second embodiment of a control system for controlling vehicular braking and suspension functions is indicated generally at 200 in Fig. 2. Elements of control system 200 that are similar to elements of control system 100 are labeled with like reference numerals in the 200 series. Control system 200 also includes an ABS/TC algorithm 206A and a VSC algorithm 206B in place of the braking algorithm 106 of control system 100. Signal processors 204 and 232 may be placed separately from their respective algorithms 206A, 206B, and 230, or they may be located in common ECU's (not illustrated in Fig. 2). Transfer signal 270 between ABS/TC algorithm 206A and VSC algorithm 206B is provided. Transfer signal 272 for load and load transfer is provided to the VSC algorithm 206B. Transfer signal 273 from the signal processor 204 is provided to the VSC algorithm 206B. Transfer signal 274 for the surface and mismatch tire detector is provided to the VSC algorithm 206B. Transfer signal 275 is provided from the VSC algorithm 206B to the suspension algorithm 234. Output signal 276 is sent from the VSC algorithm 206B to the HCU 228.

Various calculations can be made for the suspension system. For example, relative velocity can be calculated from suspension displacement if it is not directly measured. A vehicle load and load transfer signal 154, 254 can also be calculated or enhanced from a lateral acceleration signal 114, a longitudinal acceleration signal 118, and a steering wheel angle signal 122 when these are available.

A load and load transfer signal 154, 254 is used by the braking algorithms to enhance braking torque proportioning and apply and dump pulse calculations.

A turning detector signal 156, 256 (roll moment distribution) can be used to optimize vehicle handling before VSC activation and enhance brake torque distribution calculation during VSC activation. A road surface roughness and tire mismatching signal 158, 258 can be detected from suspension states and used by ABS/TC and VSC systems.

Braking/traction status information from the wheels can also be used to enhance braking algorithms by predicting pitch and roll motion in advance. Suspension algorithms and braking algorithms can be embodied in separate

ECU's 102 and 130 as illustrated in Fig. 1. In other embodiments, the suspension and braking algorithms can be integrated into a single electronic control unit.

If steering wheel angle signal 122, 222 and/or a lateral acceleration signal 114, 214 are available, then split mu detection in ABS and TC algorithms (for stand alone ABS and TC systems) can be improved.

In other examples, ECU 102 can only receive information from ECU 130. Thus, various input signals from the suspension system can be transferred to the braking system, but no signals are transferred from the braking system to the suspension system. In yet other examples, ECU 130 can only receive information from ECU 102.

Thus, various input signals from the braking system can be transferred to the suspension system, but no signals are transferced from the suspension system to the braking system.

A third embodiment of a control system for controlling vehicular braking and suspension functions is indicated generally at 300 in Fig 3. In control system 300, a single ECU 302 receives inputs signals 304 from various sensors 306 strategically placed in a vehicle. A signal processor 308 may be incorporated in the ECU 302 that delivers transfer signals 310 to an algorithm 312. The algorithm 312 delivers output signals 314 to a HCU 328 to provide a desired brake response. The algorithm 312 also delivers output signals 316 to actuators 350 to provide a desired suspension response. Control system 300 may be referred to as a totally integrated system for controlling vehicular braking and suspension.

In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been explained and illustrated in its prefened embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.

Claims

CLAIMSWhat is claimed is:

1. A control system for controlling braking and suspension functions of a vehicle, the control system comprising: a braking algorithm; a first signal processor receiving input signals from at least one sensor and transmitting transfer signals to the braking algorithm; a suspension algorithm; a second signal processor receiving input signals from at least one sensor and transmitting transfer signals to the suspension algorithm; transfer signals generated by the braking algorithm and transmitted to the suspension algorithm; transfer signals generated by the suspension algorithm and transmitted to the braking algorithm; output signals generated by the braking algorithm and transmitted to a hydraulic control unit to control vehicular braking; and output signals generated by the suspension algorithm and transmitted to a suspension actuator to control vehicular damping.

2. The control system defined in claim 1 wherein input signals to the first signal processor include a signal from a lateral acceleration sensor.

3. The control system defined in claim 1 wherein input signals to the first signal processor include a signal from a longitudinal acceleration sensor.

4. The control system defined in claim 1 wherein input signals to the first signal processor include a signal from a steering wheel angle sensor.

5. The control system defined in claim 1 wherein input signals to the first signal processor include a signal from a yaw rate sensor.

6. The control system defined in claim 1 wherein input signals to the second signal processor include a signal from a suspension state sensor.

7. The control system defined in claim 1 wherein a first electronic control unit includes the braking algorithm and the first signal processor.

8. The control system defined in claim 1 wherein a second electronic control unit includes the suspension algorithm and the second signal processor.

9. The control system defined in claim 1 wherein transfer signals from the suspension algorithm to the braking algorithm include a load and load transfer signal.

10. The control system defined in claim 1 wherein transfer signals from the suspension algorithm to the braking algorithm include a turning detector signal.

1 1. The control system defined in claim 1 wherein transfer signals from the suspension algorithm to the braking algorithm include a surface and mismatch tire detector signal.

12. The control system defined in claim 1 wherein the braking algorithm includes an anti-lock traction control algorithm and a vehicle stability control algorithm.

13. A vehicular control system comprising: a braking algorithm; a first signal processor receiving input signals from at least one sensor and transmitting transfer signals to the braking algorithm; a suspension algorithm; a second signal processor receiving input signals from at least one sensor and transmitting transfer signals to the suspension algorithm; transfer signals generated by the braking algorithm and transmitted to the suspension algorithm; output signals generated by the braking algorithm and transmitted to a hydraulic control unit to control vehicular braking; and output signals generated by the suspension algorithm and transmitted to a suspension actuator to control vehicular suspension.

14. The control system defined in claim 13 wherein the braking algorithm includes an anti-lock braking/traction control algorithm.

15. The control system defined in claim 13 wherein the braking algorithm includes a vehicle stability control algorithm.

16. A vehicular control system comprising: a braking algorithm; a first signal processor receiving input signals from at least one sensor and transmitting transfer signals to the braking algorithm; a suspension algorithm; a second signal processor receiving input signals from at least one sensor and transmitting transfer signals to the suspension algorithm; transfer signals generated by the suspension algorithm and transmitted to the braking algorithm; output signals generated by the braking algorithm and transmitted to a hydraulic control unit to control vehicular braking; and output signals generated by the suspension algorithm and transmitted to a suspension actuator to control vehicular damping.

17. The control system defined in claim 16 wherein the braking algorithm includes an anti-lock braking/traction control algorithm.

18. The control system defined in claim 16 wherein the braking algorithm includes a vehicle stability control algorithm.

19. A vehicular control system comprising: a braking and suspension algorithm; a signal processor receiving input signals from at least one sensor and transmitting transfer signals to the braking and suspension algorithm; > output signals generated by the braking and suspension algorithm and transmitted to a hydraulic control unit to control vehicular braking; and output signals generated by the braking and suspension algorithm and transmitted to an actuator to control vehicular damping.