| 摘要 |
<p>PURPOSE:To prolong the use life of a seal for a check valve element by receiving a pressing force of a return control means with a shortage preventing valve seat so that the force dees not act upon a resilient seal between the check valve body and feed pressure valve seat in a pressure discharge condition so as to sustain the resilient condition of the resilient seal for a long time. CONSTITUTION:In a pressure discharge condition, a pressing force of a return control means 37 is received by a shortage preventing valve element 17 by way of a shortage preventing valve element 23, and accordingly, it dose not act upon a resilient seal member 21 between a check-valve element 19 and a feed pressure valve seat 15. Irrespective of accumulation of operating cycles of the return control means 37, the resilient condition of the resilient seal member 21 is satisfactorily maintained for a long time, and the resilient force of a check valve element closing spring 20 can be so weak that it only elastically deform the resilient seal member 21 made of rubber or the like in a pressure holding condition. Further, in a pressure feed condition, the check valve element 19 has a low cracking pressure while having a large valve opening lift, thereby it is possible to reduce the loss of pressure.</p> |
