| 摘要 |
PROBLEM TO BE SOLVED: To provide an engine rotating speed detection valve that saves energy by reducing pressure loss of a discharge line of a fixed pump while maintaining a function of varying target differential pressure according to the rotating speed of an engine.SOLUTION: An engine rotating speed detection valve 110 is installed which guides throttle upstream pressure 18 and throttle downstream pressure 19 to a main body 47 so as to detect differential pressure thereof. The engine rotating speed detection valve 110 has a piston 56 fitted slidably in a large-diameter part 51 of a spool 53 fitted slidably in the main body 47. A small-diameter part 52 of the spool 53 is provided with a communication path 60 which is formed in an axial direction. A poppet 111 is provided with a fixed throttle 112 which communicates with the throttle upstream pressure 18 and throttle downstream pressure 19 of a flow passage 68. The diameter of the spool 53 is so selected that pressure reception area A1 of the small-diameter part 52 of the spool 53, pressure reception area A2 of the piston 56, and pressure reception area A3 at a diameter difference between the large-diameter part of the spool 53 and the piston 56 are equal. |
