Toyota Jidosha Kabushiki Kaisha

Aisin Seiki Kabushiki Kaisha

Kabushiki Kaisha Toyota Chuo Kenkyusho

Kabushiki Kaisha Toyota Toyota Jidosha Kabushiki Kaisha

Toshio Aburaya

Shuuichi Buma

Takashi Yonekawa

Osamu Takeda

Kunihito Sato

Masaki Kawanishi

Toshio Onuma

Toshiaki Hamada

Hiroyuki Ikemoto

Nobutaka Ohwa

Kouichi Kokubo

Kaoru Ohashi

Shinichi Tagawa

Shunichi Doi

Tsukasa Watanabe

Shingo Urababa

Yutaka Iguchi

Takami Sugiyama

Nobuyasu Suzumura

Toshio Oonuma

Kinihito Sato

Satoshi Naganawa

In a hydraulic active suspension system, a plurality of actuators having working fluid chambers are provided corresponding to the vehicle wheels. Each actuator is adapted to increase and decrease vehicle height in response to the pressure within its working chamber, which is controlled by a pressure control device. Vehicle speed and vehicle heights at the locations corresponding to the vehicle wheels are detected by corresponding sensors. A control device is further provided for controlling the pressure control device so that the pressures within the working fluid chambers are driven to substantially the desired pressures, the desired pressures determined by, at least, the sum of the first control parameters corresponding to the differences between the actual vehicle heights detected and the associated desired vehicle heights and the second control parameters corresponding to the changing amounts of the vehicle height differences. The second control parameters are so set that the higher the vehicle speed is, the higher the second quantities are in magnitude, enhancing the controllability and stability of the vehicle under higher vehicle speed conditions and ensuring a greater comfortability level of the vehicle under lower vehicle speed conditions.

Hydraulic active suspension system for a vehicle performing vehicle

An electronic fluid suspension system having longitudinal acceleration sensor, acceleration difference calculation means and vehicle attitude control means in addition to other fluid flow control components known in the conventional suspension system. In this system, the vehicle attitude is controlled responsive to the difference between a maximum acceleration and a minimum acceleration detected within a predetermined time interval. When dive or squat of the vehicle body is anticipated by the difference, vehicle attitude control is performed, without inappropriately responding to a momentary change in the acceleration. After the vehicle attitude control, a return control is performed to restore the original attitude and, further, a vehicle attitude correction control is performed responsive to a difference in actual front/rear heights and corresponding original heights.

Electronic controlled fluid suspension system

A suspension pressure control system applies a pressure which is proportional to a current level supplied to a solenoid of a pressure control valve to a shock absorber associated with a suspension from the valve. A height and a lateral acceleration of a car body as well as a steering angular velocity are detected. A deviation of the height from a target height is calculated. The suspension pressure is adjusted responding to the deviation and a change rate thereof. Also a correction value is calculated on the basis of the lateral acceleration for adjusting the suspension pressure responding to the correction value and a change rate thereof. Proportional coefficients for converting the change rate of the deviation and the change rate of the correction value to pressures to be corrected are corresponding to the steering angular velocity.

Pressure control system for suspension

In a hydraulic active suspension system, a plurality of actuators having working fluid chambers are provided corresponding to vehicle wheels. Each actuator is adapted to increase or decrease vehicle height in response to the hydraulic pressure within its working fluid chamber. The hydraulic pressures within the working fluid chambers are controlled to their desired pressure by associated pressure control devices. A desired pressure computing device is further provided. The computing device calculates the actual values of roll, pitch, heave and warp of a vehicle body from the vehicle heights detected by detecting devices and calculates the differences between the actual values and the associated values of roll, pitch, heave and warp determined by a desired attitude of the vehicle body to compute the desired pressures for the actuators. The degrees of the roll and/or pitch differences are set to be higher than that of the warp difference in contributing to the determination of the desired pressures.

Hydraulic active suspension system for a vehicle capable of enhancing

In a hydraulic active suspension system, a plurality of actuators having working fluid chambers are provided corresponding to vehicle wheels. Each actuator is adapted to increase and decrease vehicle height in response to the pressure within its working chamber, which is controlled by a pressure control device. Vehicle speed and lateral acceleration are detected by corresponding sensors. A control device is further provided for controlling the pressure control device by compensating values determined base upon the lateral acceleration detected. The control device is adapted to reduce the compensating values in magnitude when the vehicle speed is lower than a predetermined value under which the lateral acceleration sensor sometimes detects a false lateral acceleration, thereby reducing the possibility that the vehicle body may generate an unpleasant roll due to the erroneous control on the pressures within the working fluid chambers based upon a false lateral acceleration.

Hydraulic active suspension system for a vehicle for controlling the

A suspension pressure control system on a vehicle applies a pressure which is proportional to a current level supplied to a solenoid of a pressure control valve to a shock absorber associated with respective one of suspensions from the valve. An electronic controller controls the current level to maintain an attitude of a vehicle substantially constant in spite of any change of longitudinal and lateral acceleration, which are detected by acceleration sensors. If a driver on the vehicle closes test indication switches TSW1 and TSW2, indicates 'high' by a height indication switch HSW and rotates a steering wheel on the vehicle by B toward right, the vehicle laterally inclines such that a height of the left side of the vehicle rises up and a right side falls down responding to the rotation of the steering wheel. The inclination increases as the rotation of the steering wheel increases. The inclination decreases when the steering wheel rotates inverse direction toward the neutral position. When the steering wheel rotates beyond the neutral position toward left, the vehicle laterally inclines such that the height of the left side of the vehicle calls down and the right side rises up responding to the rotation of the steering wheel.

In a fluid pressure type active suspension in a vehicle such as an automobile in which a fluid pressure type actuator supporting a vehicle body from a wheel so as to be able to vary a vehicle height of the vehicle body relative to the wheel in accordance with a fluid pressure supplied in its fluid chamber is operated by a pressure control means which controls the fluid pressure supplied in the fluid chamber of the actuator according to certain control parameters including at least a rate of change of the vehicle height or an acceleration of the vehicle body, the control means is adapted to modify an actual value of the rate of change of the vehicle height or the acceleration of the vehicle body for use in the control of the fluid pressure to be less than the actual value thereof when the rate of change of the vehicle height or the acceleration of the vehicle body is greater than a threshold value therefor.

Fluid pressure type active suspension responsive to change of rate of

A fluid pressure type active suspension in a vehicle such as an automobile having a four wheel steering means, including a fluid pressure type actuator provided between the vehicle body and each wheel, working fluid supply and exhaust means for supplying and exhausting a working fluid to and from each actuator, vehicle height detection means for detecting vehicle height of a portion of the vehicle body corresponding to each wheel relative to the wheel, and a control means for controlling the working fluid supply and exhaust means according to control parameters including a vehicle height detected by the vehicle height detection means, wherein the control means is adapted to modify the control of the working fluid supply and exhaust means in accordance with whether a front to rear wheel steering angle ratio of the four wheel steering means is in a same phase region or an opposite phase region so that the vehicle height is controlled to be higher or lower or the rolling control is suppressed less or more according to whether the front to rear wheel steering angle ratio is in the opposite phase region or in the same phase region, respectively.

Fluid pressure type active suspension having variable performance

A suspension pressure control system applies a pressure which is proportional to a current level supplied to a solenoid of a pressure control valve to a shock absorber associated with a suspension from the valve through a cut valve, which cuts off a fluid path from the pressure control valve to the shock absorber when a line pressure is below a predetermined value and communicates the fluid path when the line pressure exceeds the predetermined value. An electronic controller controls the current level to maintain an attitude of a vehicle substantially constant in spite of any change of longitudinal and lateral acceleration, which are detected by acceleration sensors. In order to prevent an abrupt or abnormal change of the pressure of the shock absorber at an initiation of the pressure control of the controller when the vehicle is parking on a slope, the controller initiates the pressure control before the cut valve communicates the fluid path.

In a fluid pressure type active suspension in a vehicle such as an automobile, having a fluid pressure type actuator supporting a vehicle body from a wheel so as to be able to vary a height of the vehicle body relative to the wheel in accordance with a fluid pressure supplied to its fluid chamber, a fluid supply passage for supplying a working fluid to the fluid chamber of the actuator, a fluid exhaust passage for exhausting the working fluid from the fluid chamber of the actuator, and a pressure control circuit including a switching-over valve traversing the fluid supply passage and the fluid exhaust passage so as to be operated by a pilot pressure to selectively connect the fluid chamber of the actuator with either the fluid supply passage or the fluid exhaust passage for controlling the fluid pressure supplied to the fluid chamber of the actuator, a variable throttle valve for generating the pilot pressure for operating the switching-over valve from the pressure of the working fluid in the fluid supply passage by releasing a part of the working fluid therefrom, and a throttle control device for controlling the variable throttle valve so as to control the pilot pressure to a target value, the pressure control circuit comprises a means for modifying the target value to be lowered when the difference between the pressure of fluid in the fluid supply passage means at an upstream side of the pressure control circuit and the target value is smaller than a certain threshold value.

Fluid pressure type active suspension with bypass control for working

In a hydraulic active suspension system, a plurality of actuators having working fluid chambers are provided corresponding to vehicle wheels. Each actuator is adapted to increase and decrease vehicle height as the results of the supply and the discharge of working fluid to and from its working fluid chamber, respectively. Supplying and discharging devices supply working fluid to and discharge from the working fluid chamber. Vehicle height sensors detect the vehicle heights at the locations corresponding to the vehicle wheels. A control device is further provided. The control device controls the supplying and discharging devices so that the pressure within the working fluid chamber in each actuator may be a value corresponding to the sum of a basic pressure determined according to the running conditions of the vehicle and a compensating pressure determined based upon the integral value of the difference between a standard vehicle height and an actual vehicle height. When the integral value of the difference is larger in magnitude than a predeterminate value, it is reduced in magnitude by the control device so as to prevent the control with the compensating pressure from overriding the control with the basic pressure.

Hydraulic active suspension system for a vehicle capable of positively

A suspension pressure control system applies a pressure which is proportional to a current level supplied to a solenoid of a pressure control valve to a shock absorber associated with a suspension from the valve. When a pressure in a high pressure line which feeds a high pressure to the pressure control valve falls (rises), the pressure applied to the suspension is decreased (increased). Accordingly, the pressure in the high pressure line is detected by a sensor, and if it is low (high), the current level of the pressure control valve is corrected to a high value (low value). In order to prevent an abnormal pressure rise in the suspension which may be caused by an excessive pressure rise in the high pressure line during an idling operation of an engine, a correction which responds to the pressure of the high pressure line is chosen large when a vehicle speed is equal to zero or very low. In order to prevent an abnormality from occurring in the correction of the pressure which is attributable to an errorneous detected value during a failure of operation of sensor, such detected value is determined to be faulty, and in the event a fault occurred, the correction is modified to a given volume (0) which is allocated to a standard pressure in the high pressure line.

In a system for controlling the US-OS characteristic of a vehicle having front and rear suspensions, a device for changing the US-OS characteristic is provided which is adapted to alter the roll stiffness distribution between the front and the rear suspensions. A turning state quantity is detected and the changing rate of a turning state quantity is determined. A control device is further provided which is adapted to respond to the turning state quantity and the changing rate of the turning state quantity, and to control the US-OS characteristic changing device so that the higher the changing rate of the turning state quantity is, the more the US-OS characteristic may be shifted toward higher over-steer, and for the same changing rate the higher the turning state quantity is, the more the US-OS characteristic may be shifted toward higher under-steer.

US-OS characteristic control system for a vehicle responding to turning

In a hydraulic suspension system, a plurality of actuators having working fluid chambers are provided. Each actuator is adapted to increase and decrease vehicle height as the results of the supply and the discharge of working fluid to and from its working fluid chamber, respectively. Working fluid supply passages supply working fluid at supply pressure to the working fluid chambers and working fluid discharge passages discharge working fluid from the working fluid chambers. Cut-off valves and pressure control devices are provided in the supply passages and the discharge passages. Each cut-off valve is adapted to remain in its closed position whenever the supply pressure is not more than a predetermined value. Each pressure control device is adapted to control the supply of the working fluid to and the discharge from the associated working fluid chamber to adjust the pressure within the chamber. The system further comprises devices for detecting the pressures within the working fluid chambers and a device for determining the supply pressure. The pressure control devices are controlled so that their controlling pressures may substantially be equal to the pressures within the associated working fluid chambers determined by the pressure determining devices at least until the cut-off valves are opened.

Hydraulic suspension system for a vehicle with less abrupt change in

An electronic controlled fluid suspension system in which a change in a vehicle attitude is expected in advance by an advance control means responsive to a driving state detected by a driving state detection means, and the current vehicle attitude is feedback-controlled by a feedback control means. The shares of the advance control amount and the feedback control amount are calculated by a share determination means so that final control amount is determined based on the shares. Fluid flow to and from the fluid suspension is controlled by a fluid flow control means in response to the final control amount. In such control system, the advance control and the feedback control are smoothly switched, which results in improved maneuverability and stability of the vehicle.

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Toyota, Japan

Toshio Aburaya