| 摘要 |
PROBLEM TO BE SOLVED: To provide a drive unit of a hybrid-type construction machinery which can reduce as much as possible a rise in pressure of a hydraulic motor and a communication valve circulation passage during regeneration/braking. SOLUTION: The spool spr of a communication valve 28 is energized by a spring 28b in the right directions, and the small diameter part 28c of the spool borders a chamber 28g which is connected to the opening 28(B) on the port B side through the medium of a passage fB. The large diameter part on the right side of the small diameter part of the spool receives signal pressure sg1, and a drain passage 28a which is a small-diameter hole is provided from the large diameter part on the left side of the spool to the small diameter part. Then a horizontal hole 28d and a horizontal hole 28e are provided. The horizontal hole 28d connects the passage 28a to the chamber 28g, and the horizontal hole 28e guides the passage 28a to an intermediate chamber 28h. When the signal pressure sg1 is applied, the openings 28(B) and 28(A) are connected to each other. At this time, the horizontal hole bordering the chamber 28g and the horizontal hole bordering the intermediate chamber 28h, namely the tank side are connected to each other. Because of this, a rise in pressure based on a confinement phenomenon of the hydraulic motor and the circulation passage of the communication valve 28 is controlled. COPYRIGHT: (C)2010,JPO&INPIT |
