| 摘要 |
PURPOSE:To maintain pressure in an accumulator within a predetermined range in a device for intermittently supplying the pressure in the accumulator by means of a valve, by operating a pump during only a predetermined period of time every time an opening and closing operation of the valve reaches a predetermined frequency. CONSTITUTION:When hydraulic pressure in an accumulator 28 is utilized by a transmission mechanism 22 to be reduced, an opening frequency of solenoid valves 24 and 25 operated by a control unit 26 is counted by a counter 41, and when the opening frequency reaches a predetermined value, an output pulse P0 is outputted from the counter 41, and simultaneously content of the counter 41 is reset. A first timer 42 responds to the output pulse P0, and raises its output voltage V01 to a high level during only a predetermined period of time to close a switch 43. As a result, a motor 34 is driven to operate a hydraulic pump 29, and thereby the increase the pressure in the accumulator 28. Since decrease in pressure created by one time of operation of the solenoid valves 24 and 25 is substantially constant, it is possible to attain accumulation corresponding to the count number, and the pressure in the accumulator does not exceed a preset pressure by the provision of a relief valve 36. |
