Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
1998-10-05
2001-03-13
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C180S041000, C280S005500, C280S006157, C280S005514, C280S124157
Reexamination Certificate
active
06202010
ABSTRACT:
INCORPORATION BY REFERENCE
The disclosure of Japanese Patent Application No. HEI 10-5167 filed on Jan. 13, 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 adjusting an actual vehicle height to a predetermined target vehicle height.
2. Description of Related Art
A vehicle height adjust control apparatus as described in, for example, Japanese Patent Application Laid-Open No. HEI 2-3515, includes actuators capable of changing a vehicle height, and a vehicle height detection device for detecting the vehicle height. The apparatus performs vehicle height adjust control by integrating the amount of shift of the detected vehicle height from a predetermined target vehicle height and, when the integral of the amount of shift exceeds a predetermined value, controls the actuators so that the detected vehicle height becomes equal to the target vehicle height. This manner of control avoids starting a vehicle height adjusting operation in response to a temporary vehicle height change, thereby preventing unnecessary vehicle height adjustment.
Japanese Patent Application Laid-Open No. SHO 62-0241716 describes a technology wherein the detected vehicle height sampling time is reduced when a detected vehicle height is out of an allowable range around a target vehicle height, in comparison with a case where the detected vehicle height is within the allowable range. This prevents overshoot of the vehicle height resulting from a delay of the vehicle height detection during vehicle height adjustment and also prevents unnecessary performing of vehicle height adjusting operations due to an excessively high sensitivity in the vehicle height detection.
However, these conventional apparatus do not consider either the vehicle height changes while the vehicle is stopped or the difference between the vehicle height changing rate during the vehicle body raising control and the vehicle height changing rate during the vehicle body lowering control, and therefore suffer from several problems. That is, if the vehicle is stopped with the engine turned off, there is a high possibility of a vehicle height change due to a change in the baggage weight on the vehicle, or a high possibility of a vehicle height reduction due to a temperature reduction of fluid in an apparatus wherein hydraulic actuators and the like are used. Considering such circumstances, it is desirable to adjust the vehicle height to a target vehicle height more quickly at the time of starting the engine than during the running of the vehicle, If it is determined whether to start vehicle height adjustment on the basis of the integral of the amount of shift of the vehicle height as in the aforementioned conventional apparatus, it requires an undesirably long time to start the vehicle height adjustment during an initial period following starting of the engine.
Additionally, the vehicle body is raised against the vehicle's own weight by operating the actuators, whereas the vehicle body can be lowered by using the vehicle's own weight. Therefore, the vehicle height changing rate becomes greater when the vehicle height is being reduced than when the vehicle height is being increased. Consequently, vehicle height adjust control apparatus that do not consider the vehicle height changing rate as in the aforementioned apparatus have a problem as there is a high possibility of downward overshoot of the vehicle body during the lowering control of the vehicle body.
SUMMARY OF THE INVENTION
The invention has been achieved by taking into account the vehicle height changes while the vehicle is stopped and the difference between the vehicle height changing rate during the raising control and the vehicle height changing rate during the lowering control.
It is an object of the present invention to provide a vehicle height adjust control apparatus capable of performing precise vehicle height adjustment when a vehicle height change is likely to exist and when the existence of a vehicle height change is less likely.
It is another object of the invention to provide a vehicle height adjust control apparatus that substantially prevents vehicle height overshoot resulting from the difference between the vehicle height changing rate during the raising control and the vehicle height changing rate during the lowering control.
According to one aspect of the invention, there is provided a vehicle height adjust control apparatus including an actuator capable of changing a vehicle height, a vehicle height detection device for detecting the vehicle height, a start determining device for determining whether to start vehicle height adjustment by comparing the vehicle height detected by the vehicle height detection device with a predetermined target vehicle height, and a vehicle height adjust control device for adjusting the vehicle height. If it is determined that vehicle height adjustment is to be started, the vehicle height adjust control device controls the actuator so that the vehicle height detected by the vehicle height detection device becomes substantially equal to the target vehicle height. During an early period immediately after an engine is started, the start determining device uses a threshold that is different from a threshold used after the early period to make determinations regarding the start of the vehicle height adjustment.
In the vehicle height adjust control apparatus, during an early period immediately after the start of the engine, the start determining device determines that vehicle height adjustment is to be started, even if the vehicle height is only slightly shifted from the target vehicle height. After the early period, on the other hand, the start determining device makes the vehicle height adjustment starting determination only if the vehicle height is considerably shifted from the target vehicle height. That is, the sensitivity to vehicle height shift in determining whether to start vehicle height adjustment is relatively high during the early period, and the sensitivity is relatively low after the early period. Therefore, the vehicle height adjust control apparatus of the invention prevents unnecessary vehicle height adjustment in response to a temporary vehicle height change in a normal occasion, and quickly performs vehicle height adjustment during the early period immediately after the engine is started, during which there is a high probability of a vehicle height change occurring during the stop of the vehicle. Consequently, vehicle height adjustment is precisely performed when it is necessary.
The vehicle height adjust control apparatus according to the first aspect of the invention may further have the following features. That is, the start determining device may compare an integral of the amount of shift of the vehicle height detected by the vehicle height detection device from the target vehicle height, which amount of shift is greater than a first predetermined value, with a second predetermined value. If the integral of the amount of shift is greater than the second predetermined value, the start determining device determines that the vehicle height adjustment is to be started. The first predetermined value used during the early period is smaller than the first predetermined value used after the early period. Therefore, during the early period immediately after the start of the engine, the start determining device integrates the amount of shift of the detected vehicle height from the target vehicle height if the amount of shift is greater than a relatively small value. After the early period, the start determining device integrates the amount of shift if the amount of shift becomes greater than the value that is greater than the small value used during the early period. Consequently, during the early period, the start determining device makes the vehicle height adjustment starting determination even for a relatively small shift of the
Hashimoto Yoshiyuki
Sato Atushi
Shono Shoichi
Beaulieu Yonel
Cuchlinski Jr. William A.
Oliff & Berridge PLC.
Toyota Jidosha & Kabushiki Kaisha
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