Toyota Jidosha Kabushiki Kaisha

Atushi Sato

Shoichi Shono

Masaaki Tabata

Yoshiyuki Hashimoto

Kenji Harada

Masaki Kanatani

In a vehicle height adjust control apparatus and method for changing the vehicle height using actuators, the incidence of noises produced during the switching of actuators is reduced and good durability or long service life of the actuators is achieved. Based on a vehicle speed detected by a vehicle speed sensor, a microcomputer calculates a forward-backward acceleration. If the forward-backward acceleration is equal to or less than a first predetermined value, a vehicle height deviating from a target vehicle height is adjusted by a normal operation. If the forward-backward acceleration is greater than the first predetermined value but not greater than a second predetermined value, the determination for starting vehicle height adjustment is prevented. If the forward-backward acceleration is greater than the second predetermined value, the vehicle height adjustment is suspended. Therefore, the apparatus allows the second predetermined value to be set to a large value so as to reduce the frequency of the suspension and restart of vehicle height adjustment while reliably preventing the start of vehicle height adjustment when necessary, thereby reducing the frequency of actuator switching operations.

Vehicle height adjust control apparatus and method

A vehicle height adjust control apparatus that increases the durability or service life of a fluid system, including a fluid supply-discharge device and a fluid actuator, can have a pressure sensor and vehicle height sensors. If a microcomputer determines that the pressure detected by the pressure sensor is greater than a predetermined pressure, the microcomputer changes a target vehicle height to a vehicle height presently detected by the vehicle height sensors. In a preferred construction, the target vehicle height is changed to the vehicle height presently detected, if it is determined that the detected pressure remains greater than the predetermined pressure for at least a predetermined length of time. The predetermined length of time is changed to a longer time when the fluid temperature is relatively low. These additional determination conditions prevent unnecessary or ineffective changes of the target vehicle height due to by a sensor abnormality or a fluid temperature change.

A vehicle height adjust control apparatus and method prevents interference between a vehicle and a road surface due to a vehicle height reduction caused by an occupant or load added during a stop of the vehicle and minimizes unnecessary or ineffective operation of actuators while the vehicle is stopped with a brake pedal depressed. The apparatus has a vehicle sensor for detecting a vehicle speed, and a brake switch for detecting a brake pedal depressing operation. When the vehicle is stopped and the brake pedal is depressed, a microcomputer maintains a normal determination condition for starting a vehicle height adjustment to raise the vehicle body, but prevents a vehicle height reducing adjustment from lowering the vehicle body or uses a severe determination condition for starting a vehicle height reducing adjustment, thereby restricting the vehicle height adjustment only in the reducing direction. The microcomputer also limits the operating duration of the actuators and the magnitude of change in the vehicle height during performance of a vehicle height adjustment.

A vehicle height adjust control apparatus and method adjusts an actual vehicle height to a target vehicle height using a microcomputer that controls an electric motor, leveling valves and an accumulator valve on the basis of the actual vehicle height detected by vehicle height sensors, so as to eliminate any deviation of the actual vehicle height from the target vehicle height. If a hydraulic fluid temperature detected by a fluid temperature sensor is very low or very high, the microcomputer suspends the vehicle height adjusting control and the supply of hydraulic fluid to an accumulator by stopping the operation of the electric motor and a hydraulic pump and/or switching the valves to a closed state. The suspending control thereby prevents very high and low viscosities of the hydraulic fluid, or very low and high fluidities thereof, which prevent an undesirable increase of the load on the hydraulic pump and an undesirable decrease of the ejecting performance thereof.

A vehicle height adjust control apparatus and method precisely performs vehicle height adjustment while preventing unnecessary vehicle height adjustment. In the apparatus, a microcomputer compares the amount of shift of a vehicle height detected by a vehicle height sensor with a first predetermined value. If the amount of shift is greater than the first predetermined value, the microcomputer integrates the amount of shift. The integral of the amount of shift is compared with a second predetermined value. If the integral is greater than the second predetermined value, the microcomputer determines that vehicle height adjustment should be started. The first and/or second predetermined values used in an initial period immediately after an engine is started are smaller than the first and/or second predetermined values used after the initial period. The sensitivity to vehicle height shift in determining whether to start vehicle height adjustment is thus enhanced during the initial period immediately after the engine is started, so that vehicle height adjustment is promptly performed during the initial period, during which there is a high likelihood that a vehicle height change occurred during the stop of the vehicle.

The method of controlling a vehicle height adjust apparatus for a vehicle that includes an actuator capable of changing a vehicle height, a height detector that detects the vehicle height and a controller linked to the actuator that receives parameters indicating a state of the vehicle includes the steps of detecting the vehicle height and at least one of a steering angle of a steering wheel of the vehicle and a differential-limited state of wheels of the vehicle, and controlling the actuator with the controller to adjust the vehicle height to approach the target vehicle height if the steering angle is not greater than a predetermined steering angle and/or the wheels are not in a differential-limited state.

A vehicle height adjust control apparatus includes a plurality of actuators provided between a vehicle body and a plurality of wheels that are capable of changing a vehicle height at a wheel position corresponding to each of a plurality of wheels of the vehicle, a vehicle height detector that detects an actual vehicle height at different positions, a controller for controlling the actuators to eliminate deviations of each of the actual vehicle heights detected by the vehicle height detector from corresponding predetermined target vehicle heights and a simultaneous controller linked with the controller that simultaneously changes the actual vehicle height at individual wheel positions by controlling the actuators if the actual vehicle heights detected by the vehicle height detector are deviated from the corresponding target vehicle heights by at least a predetermined value toward the same side.

A vehicle height adjust control apparatus, incorporating a slope determination apparatus, has a vehicle speed sensor, a vehicle height detector that detects a rear vehicle height of a rear portion of a vehicle body and front vehicle heights at the right and left front wheel positions, and actuators for changing the front and rear vehicle heights. In a case where the detected vehicle speed or an acceleration calculated from the detected vehicle speed is small and where the difference between the detected front vehicle heights at the right and left wheel positions is small and the averaged front vehicle height considerably deviates from a target vehicle height, a microcomputer determines that the vehicle is on a steep slope. When it is determined so, the microcomputer inhibits automatic vehicle height adjust control including the control of the actuators, thereby preventing undesired events that immediately after the vehicle moves from the steep slope onto a horizontal road, the vehicle has an awkwardly tilted appearance or the vehicle body interferes with a road surface.

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Susono, Japan

Atushi Sato