| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic driving device for saving the energy by reducing pressure losses of a discharge line of a fixed pump while maintaining the function of changing the target differential pressure according to the engine speed. SOLUTION: The hydraulic driving device 10 has a revolving number detection valve 46 which leads the pressure Pp1 of the throttle upstream pressure 18 and the pressure Pp2 of the throttle downstream pressure 19 to detect the differential pressure thereof. In the revolving number detection valve 46, a piston 56 is slidably inserted on the large diameter part side of a spool 53 which is slidably inserted in a body 47. A spring 45 is internally fitted to the small diameter part side of the spool 53, and a fixed throttle 41 is provided in an inner hole of the spool 53 and communicated with the throttle upstream pressure 18 and the throttle downstream pressure 19. The diameter of the spool 53 is selected so that the pressure-receiving area A1 on the small diameter part side of the spool 53, the pressure-receiving area A2 of the piston, and the pressure-receiving area A3 of the differential diameter between the large diameter part of the spool and the piston 56 are same. COPYRIGHT: (C)2009,JPO&INPIT
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