Control valve of exhaust recirculation apparatus

Abstract

A control valve of an exhaust recirculation apparatus comprises an expansible vacuum chamber communicating with a venturi portion and having a first diaphragm and a spring urging the diaphragm to expand the chamber, an expansible exhaust pressure chamber having a second diaphragm disposed to oppose the first diaphragm at a distance and communicating with an exhaust inflow chamber, a control chamber disposed between the above chambers and defined by the first and second diaphragms and a frame mounting the first and second diaphragms thereon. The first and second diaphragms are connected by a bracket to which a seal member is secured through a block. In the control chamber is disposed a conduit one end of which has an opening facing the seal member with a gap therebetween, the other end communicates with a throttle portion and an exhaust gas recirculation valve provided in an exhaust recirculation passage. Upon increase of vacuum at the venturi portion, the diaphragms are moved to cause the seal member to approach and seal the opening in the conduit, whereby vacuum in the conduit is increased to open the exhaust recirculation of the exhaust gas, exhaust pressure in the exhaust inflow chamber is decreased to move the diaphragms so as to separate the seal member from the opening, so that the vacuum in the conduit will be decreased a little for the exhaust recirculation valve to be held at a suitable opening.