Patent ID: 8863642

Claim:
A device for controlling the stroke of a clutch actuator driven by a working fluid, said clutch actuator operating a clutch installed between an engine and a transmission in a power transmission device for a vehicle, wherein: said clutch actuator is provided with a mechanical stopper which limits the stroke of said clutch actuator so that there exists a maximum value of the stroke of said clutch actuator, said device for controlling the stroke of a clutch actuator comprises a flow rate control valve for controlling the amount of the working fluid in said clutch actuator, a valve actuator for operating a valve body of said flow rate control valve, a stroke sensor for detecting a real stroke of said clutch actuator, a target stroke-setting means for setting a target stroke of said clutch actuator, and a flow rate control valve control device for controlling said valve actuator depending upon a feedback operation amount which is operated based on a deviation between the real stroke of said clutch actuator and the target stroke; wherein, said flow rate control valve is connected to a communication passage communicated with said clutch actuator, to a pressure source passage communicated with a working fluid pressure source, and to a discharge passage for discharging the working fluid from said clutch actuator, and is so constituted that, at the neutral position of said valve body, said communication passage is cut off from said pressure source passage and said discharge passage, and said flow rate control valve control device is provided with a neutral position learning device for learning the neutral position of said valve body; wherein, said neutral position learning device executes the learning if the stroke of said clutch actuator is greater than a predetermined stroke but is smaller than said maximum value of the stroke, and said neutral position learning device learns, as a neutral position operation amount, an operation amount of said valve actuator at a moment when a rate of change in the detection signal of said stroke sensor becomes smaller than a predetermined value, and said flow rate control valve control device controls said valve actuator by correcting said feedback operation amount by the natural position operation amount.