Patent ID: 8209086

Claim:
A vehicle height adjustment device comprising: a vehicle height adjustment unit, disposed between an axle for supporting respective wheels of a vehicle and a vehicle body, that changes a vehicle height at each wheel of the vehicle through controlling supply and discharge of a fluid; a vehicle height sensor that detects the vehicle height at each wheel; a vehicle height control unit that executes a vehicle height control, which includes a standard vehicle height control for making the vehicle height at each wheel equal to a predetermined standard vehicle height by controlling the vehicle height adjustment unit; a pressure sensor that detects a fluid pressure within the vehicle height adjustment unit; a control stop unit that temporarily suspends the execution of the vehicle height control by the vehicle height control unit if the detected fluid pressure exceeds a threshold pressure; a road surface estimation unit that estimates a condition of a road surface over which the vehicle travels; and a control recovery unit that cancels the temporary suspension of the vehicle height control by the control stop unit and allows the vehicle height adjustment unit to change the vehicle height, while the control stop unit temporarily suspends the vehicle height control unit from performing the control, if the road surface estimation unit estimates that the road surface over which the vehicle is traveling satisfies a predetermined condition, wherein the vehicle includes a vehicle height calculation unit that calculates a first sum of vehicle heights at two of the wheels arranged on one diagonal line of the vehicle and a second sum of vehicle heights at two other wheels arranged on another line of the vehicle; and the road surface condition is estimated based on a comparison between the first sum and the second sum.