PURPOSE: To aim at preventing a driving feeling from worsening, by installing a capacity selector mechanism for opening of closing a first bypass passage and a control valve, gradually closing all passages by means of dynamic pressure of reflux gas inside a second bypass passage with closure of this passage both inside a discharge chamber.
CONSTITUTION: Compressed high temperature discharge gas is fed, with pressure, to a back pressure chamber 57 via a high pressure pipe 60, while a spool 47 is moved to a regular closing position together with a discharge valve 44 and a valve guard 46, closing a first bypass passage 56. Therefore, the whole quantity of gas discharged to the discharge chamber 22 passes through a second passage 65 alone and is made to flow back to a swash plate chamber 8 whereby a control valve 67 tries to be moved in a direction to close the passage 65 by dint of dynamic pressure of reflux gas, but since the intake of pressure compensating for negative pressure in a back pressure chamber 69 is throttled by a pressure intake hole 70, its motion is regulated so as to come sluggish, and a gas quantity is gradually increased till the control valve 67 comes to 100% operation having closed the passage 65 completely so that with this increase, engine load also slowly goes up, therefore a shock is effectively relievable.
KAWAI KATSUNORI
DEGUCHI HIROYUKI
