Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
1998-10-05
2001-08-28
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C701S048000, C180S041000, C280S005500, C280S005514, C280S006157
Reexamination Certificate
active
06282470
ABSTRACT:
INCORPORATION BY REFERENCE
The disclosure of Japanese Patent Application No. HEI 10-4281 filed on Jan. 12, 1998 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a vehicle height adjust control apparatus and method for automatically adjusting a vehicle height to a predetermined target vehicle height.
2. Description of Related Art
A vehicle height adjust control apparatus described in Japanese Patent Application Laid-Open No. Hei 2-246812, for example, includes an actuator provided between a vehicle body and wheels, the actuator being capable of changing a vehicle height by fluid supplied and discharged, a supply-discharge device for supplying fluid into and discharging it from the actuator, and a vehicle height detection device for detecting a vehicle height. The supplying of fluid to and the discharging of it from the actuator performed by the fluid supply-discharge device is controlled on the basis of the detected vehicle height so that the vehicle height detected becomes equal to a target vehicle height.
In this related technology, however, if the vehicle height cannot be increased to a target vehicle height despite a considerably high fluid pressure in the fluid supply-discharge device and the actuator, due to an excessively large superimposed load, the ability of the fluid supply-discharge device and the actuator, an abnormality in the vehicle height detection by the vehicle height detection device, and the like, the fluid pressure in the fluid supply-discharge device and the actuator is further increased, or the fluid supply-discharge device and the actuator continue operating for vehicle height adjustment. Such operating conditions are unfavorable in terms of the durability or service life of the fluid supply-discharge device and the actuator. Furthermore, if the target vehicle height is reached, the pressure in the actuators and the fluid supply-discharge device becomes abnormally high, which is also unfavorable in terms of the durability or service life of the fluid supply-discharge device and the actuator. The aforementioned undesirable conditions are remarkable when the fluid temperature is low, particularly in a case where the fluid is a hydraulic oil whose viscosity greatly varies depending on temperature.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a vehicle height adjust control apparatus and method that increases the durability or service life of a fluid system that includes a fluid supply-discharge device and a fluid actuator.
According to one aspect of the invention, there is provided a vehicle height adjust control apparatus including an actuator capable of changing a height of a vehicle, a fluid supply-discharger that supplies fluid to the actuator and discharges the fluid from the actuator, a vehicle height detector that detects a vehicle height, a vehicle height adjustment controller that controls supply of the fluid to and discharge of the fluid from the actuator by the fluid supply-discharger, on the basis of the vehicle height detected by the vehicle height detector, so that the vehicle height detected by the vehicle height detector becomes substantially equal to a predetermined target vehicle height, and a pressure detector for detecting a pressure of the fluid supplied to the actuator. If it is determined that the pressure detected by the pressure detector is greater than a predetermined pressure, the target vehicle height is changed to a changed target vehicle height equal to the vehicle height detected by the vehicle height detector. The actuator may be provided between a vehicle body and each wheel.
If the vehicle height cannot be increased to the target vehicle height despite a considerably high fluid pressure in the fluid supply-discharger and the actuator, because of an excessively large load superimposed on the vehicle, the ability of the fluid supply-discharger and the actuator, an abnormality in detection of the vehicle height by the vehicle height detector, or other reasons, the target vehicle height is changed to the vehicle height detected by the vehicle height detector, on condition that the pressure detected by the pressure detector is greater than the predetermined pressure. Therefore, it becomes possible for the vehicle height adjustment controller to adjust the vehicle height substantially to the target vehicle height by controlling the supply of the fluid to and the discharge thereof from the actuator by the fluid supply-discharger. In this manner, the vehicle height adjust control apparatus prevents a situation where the fluid pressure in the fluid supply-discharger and the actuator becomes very high and a situation where the fluid supply-discharger and the actuator continue operating for a long time. Consequently, the durability or service life of the fluid supply-discharger and the actuator are increased.
As for the condition for changing the target vehicle height, it may be determined that the pressure detected by the pressure detector is greater than the predetermined pressure if the pressure detected by the pressure detector remains greater than the predetermined pressure for at least a predetermined length of time. Therefore, it becomes possible to prevent a change of the target vehicle height due to a false pressure detection, for example, wherein the detected pressure is instantaneously increased to a very high level by contamination of a pressure detection signal with noise of the like.
The vehicle height adjust control apparatus may further include a temperature detector that detects a temperature of the fluid supplied to the actuator, wherein the predetermined length of time is longer when the temperature of the fluid detected by the temperature detector is relatively low than when the temperature of the fluid detected by the temperature detector is relatively high. Therefore, if the temperature of the fluid, in particular, hydraulic fluid, is low so that the pressure of the fluid supplied to the actuator becomes higher in comparison with a case where the fluid temperature is high, the target vehicle height is not changed until the detected pressure continues to be above the predetermined pressure for a time that is longer than the time used when the fluid temperature is high. Consequently, the vehicle height adjust control apparatus prevents ineffective or unnecessarily frequent changes of the target vehicle height even when the fluid temperature is low.
According to another aspect of the invention, there is provided a vehicle height adjust control apparatus including an actuator capable of changing a height of a vehicle, a fluid supply-discharger that supplies fluid to the actuator and discharges the fluid from the actuator, a vehicle height detector that detects a vehicle height, a vehicle height adjustment controller that controls supply of the fluid to and discharge of the fluid from the actuator by the fluid supply-discharger, on the basis of the vehicle height detected by the vehicle height detector, so that the vehicle height detected by the vehicle height detector becomes substantially equal to a predetermined target vehicle height, a pressure detector that detects a pressure of the fluid supplied to the actuator, and a suspension controller that, if it is determined that the pressure detected by the pressure detector is greater than a predetermined pressure, suspending the supply of the fluid to the actuator for a predetermined length of time and then allowing the supply of the fluid to the actuator. If it is determined that the pressure detected by the pressure detector is greater than the predetermined pressure while the supply of the fluid to the actuator is allowed after suspension of the supply of the fluid by the suspension controller, the target vehicle height is changed to a changed target vehicle height equal to the vehicle height detected by the vehicle height detector.
In this vehicle height adjust control apparatus, th
Sato Atushi
Shono Shoichi
Tabata Masaaki
Beaulieu Yonel
Cuchlinski Jr. William A.
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
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