Abstract: To avoid placing an unnecessary load on a prime mover, a pump control arrangement monitors automotive vehicle speed and inhibits an increase in pump output above a basic estimate when the vehicle speed is below a predetermined level. If the speed falls below the level while the pump output is above the basic estimate, the present operating mode is maintained for a given period before being reduced to the basic estimate level.

Abstract: In order to reduce the pump load on a prime mover and improve fuel consumption characteristics, the mode in which a variable displacement pump is operated is varied in accordance with a consumption estimate which is modified using engine speed and lateral acceleration data inputs. A basic consumption estimate is derived based on sensor inputs which are indicative of the amount of work a servo is producing and increased by increasing the level based on the lateral acceleration level. The amount by which the basic estimate is boosted is variable with vehicle speed and/or lateral acceleration level.

Abstract: An active suspension system is disclosed in which in order to eliminate the undesired rapid lifting of the vehicle upon starting of the engine, the discharge from a fluid supply pump at such time is controlled to a level lower than that achieved when the system normally operates. In order to improve the fuel consumption of the engine, a measure is further disclosed in which the discharge from the fluid supply pump is controlled to match with that actually needed for the suspension.

Abstract: An active suspension system for an automotive vehicle is provided. This suspension system includes generally a hydraulic circuit which supplies pressurized fluid to hydraulic cylinders for controlling vehicle height and attitude. The hydraulic circuit includes a line pressure holding unit and a line pressure control unit. The line pressure holding unit is operable to hold the line pressure when the line pressure is lowered below a preselected pressure level after stopping supply of the pressurized fluid to the hydraulic cylinders. The line pressure control unit restricts a flow rate of the pressurized fluid to the hydraulic cylinders to build up the line pressure gradually until the line pressure reaches the preselected pressure level after starting the supply of pressurized fluid to the hydraulic cylinders to allow smooth adjustment of vehicle height and attitude.

Abstract: An active suspension control system includes working fluid cylinders which are respectively disposed between a vehicle body and suspension members which support road wheels rotatably. The working fluid cylinder includes a piston slidably arranged therein for adjusting a relative distance between the vehicle body and the suspension member to suppress vehicle attitude change. The system includes a pressure control unit which is responsive to vehicle attitude change to control fluid pressure to be supplied to the working fluid cylinders to cause the piston to slide such that an increase in the fluid pressure is provided which is lower than a decrease in the fluid pressure. This restricts friction, caused by fluid pressure elevation in the working fluid cylinder, created between the piston and a seal ring to allow the piston to move smoothly.

Abstract: An actively controlled suspension system comprises a hydraulic cylinder disposed between a vehicle body and a suspension member rotatably supporting a vehicular wheel, the hydraulic cylinder defining therein a working chamber, a pressure source including a pump associated with an automotive internal combustion engine to be driven by the output of the engine, a pressure control valve having a first port connected to the working chamber, a second port connected to the pressure source via a supply line and a third port connected to the pressure source via a drain line, the pressure control valve being variable of valve position for selectively establishing and blocking fluid communication between the first port and the second port and between the first port and the third port for adjusting fluid pressure in the working chamber for controlling suspension characteristics, a vertical acceleration sensor for monitoring vertical acceleration exerted on the vehicular body to produce a vertical acceleration indicative

Abstract: A fail detecting system for an electromagnetic actuator avoids influence of a dither signal in detection of a failure of the electromagnetic actuator. Avoidance of influence of the dither signal is achieved by performing a comparison of a suspension control command with a driver current applied to the electromagnetic actuator in absence of the dither signal. An error value between the suspension control command and the driver current obtained through the comparison is compared with a predetermined fault detecting criterion for judging a failure of the electromagnetic actuator when the error value is greater than the fault detecting criterion.

Abstract: An actively controlled suspension system employs a pressure control valve which is operable in response to a control signal and controls fluid pressure in the fluid chamber of a hydraulic cylinder as a replacement for the conventional hydraulic shock absorber. The pressure control valve is associated with a controller which detects bounding and rebounding acceleration and stroke speed in bounding and rebounding motion for deriving a control signal to operate the pressure control valve to absorb vibration energy to be transmitted between a vehicle body and a suspension member.

Abstract: A height regulation system for an automotive vehicle to generally adjust a vehicular height level within a predetermined height range includes a variable pressure chamber, in which the fluid pressure is adjusted to adjust the relative distance between the vehicular body and a vehicular wheel. The system includes a control circuit including a sensor for monitoring vehicular height for detecting an actual vehicular height beyond the predetermined height range for triggering height adjustment operation. The control circuit limits the variation range of the fluid pressure within a predetermined range so as to avoid excess adjustment of the pressure at any vehicular condition.

Abstract: An active suspension system derives a target pressure to adjust fluid pressure in a working chamber of an active cylinder on the basis of a difference between an actual height level and a desired or target vehicular height level. Pressure supply for the working chamber is so controlled as to establish the target height. The system detects a vehicular parking state in which the vehicle speed is zero and a road wheel is locked and limits the variation range of the fluid pressure in the working chamber at the target pressure.

Abstract: An active suspension system includes a pressure holding mechanism with a pressure holding valve means which is maintained in conductive state for a given period in which the fluid pressure in a working chamber is gradually adjusted toward a predetermined neutral pressure level after turning OFF of a power switch. The pressure holding valve is, on the other hand, maintained in non-conductive state for a given period until the fluid pressure is adjusted to the neutral pressure after turning ON of the power switch. A control means is provided for performing suspension control operation in response to various suspension control parameters for adjusting fluid pressure in a working chamber of a cylinder for regulating vehicular height and vehicular attitude.

Abstract: An active suspension system includes a pressure holding mechanism with a pressure holding valve means which is maintained in conductive state for a given period in which the fluid pressure in a working chamber is gradually adjusted toward a predetermined neutral pressure level after turning OFF of a power switch. The pressure holding valve is, on the other hand, maintained in non-conductive state for a given period until the fluid pressure is adjusted to the neutral pressure after turning ON of the power switch. The system further includes a detector for detecting resumption of power supply after a short period of turning OFF of the power supply.

Abstract: An active suspension system is provided with a fail detector for detecting failure of control system which includes sensors, control unit, control valves and so forth. Fail-safe operation is taken place by closing a fluid circuit across a working chamber in a suspension system disposed between a vehicular body and a road wheel and a pressure control valve for adjusting the fluid pressure in the working chamber, and by adjusting the fluid pressure in the closed circuit substantially at a predetermined neutral pressure. The system further includes a vehicular driving condition monitor for monitoring vehicular driving condition. When faulty condition of the control system is cured or terminated, active suspension control is resumed at a timing when the vehicular driving condition monitor detects a predetermined vehicular driving condition stable enough for permitting resumption of active suspension control.

Abstract: An actively controlled suspension system includes a fail-safe control system which detects abnormality of the output of a sensor to instantly perform fail-safe operation for ordering a neutral suspension mode with disabling the suspension control. The fail-safe system maintains the suspension system in the neutral mode for a predetermined period of time and performs checking of the output of the sensor after expiration of the predetermined period. The fail-safe system resumes suspension control when the sensor output as checked after expiration of the predetermined period is within a predetermined value range which is set about a known neutral position.

Abstract: An actively controlled suspension system monitors acceleration exerted on a vehicular body for producing a vehicular attitude change indicative suspension control parameter. Acceleration dependent suspension control is performed based on the vehicular attitude change indicative suspension control parameter for suppressing vehicular body attitude change. The suspension control system further monitors engine driving condition to detect unstable engine driving condition. The engine driving condition detector disables the acceleration dependent suspension control when the unstable condition of the engine is detected. Disabling of the acceleration dependent suspension control while the unstable engine driving condition is maintained, avoids influence of the vehicular body vibration caused by engine vibration which is caused by fluctuation of engine outputs in unstable condition.

Abstract: An actively controlled suspension system which successfully prevents a vehicular height from abruptly changing even when failure of a vertical acceleration occurs. The actively controlled suspension system introduces a technology in performing suspension control, such as bouncing control, to shape a vehicular attitude indicative sensor signal, such as vertical acceleration indicative signal by slicing the sensor signal level at a predetermined slice level. In view of suppression of abrupt change of vehicular height at any vehicular driving condition, the slice level introduced in the present invention, is variable depending upon a vehicle speed.

Abstract: A suspension control system employs a road sensor monitoring road roughness or smoothness and producing a road condition indicative signal. The control system also employs other sensor or sensors for monitoring at least one preselected suspension control parameter, such as vehicle speed, steering angular variation and so forth, other than road roughness. The suspension switches between relatively hard and relatively soft characteristics based on the preselected suspension control prameters. In order to make suspension control more precisely suited to the vehicle driving conditions, the control characateristics of the suspension system are adjusted depending upon the road condition.

Abstract: A vehicle height control system controls suspension assemblies to adjust the vehicle height within a predetermined height range. The vehicle height control system is further active to reduce differences in height at respective positions of the vehicle body so as to be within a predetermined acceptable height difference range.

Abstract: An automotive height control system for an automotive vehicle includes an actuator disposed within a vehicle suspension system for adjusting the vertical dimension between a vehicle body and a wheel axle. The actuator is connected to a controller to receive a control signal which orders adjustment of the vehicle height. The height control system further includes a damping characteristics controller cooperative with the actuator for adjusting damping characteristics of the suspension system according to the vehicle height. In addition, the system is provided with a vehicle height sensor which monitors the height of the vehicle from the road surface and provides a vehicle height indicative signal. A fail-safe system detects abnormal height conditions as indicated by the vehicle height indicative signal to produce a fail-safe signal. The actuator and the damping characteristics controller respond to the fail-safe signal by equalizing their internal pressures.