Exhaust gas cleaning system for internal combustion engines

Claim 2

In an automobile engine having an air intake system including an intake manifold, a catalytic converter, an exhaust system including an exhaust manifold and conduit means connecting said exhaust manifold to said converter, the improvement which comprises: an air pump; a change-over valve means, activated by a vacuum from said air intake system, having an inlet port communicating with said air pump, a first outlet port communicating with said exhaust system of the engine upstream of said catalytic converter, and a second outlet port communicating with said exhaust system of the engine upstream of said catalytic converter and communicating with said intake system of the engine via a first conduit, wherein said first conduit is branched with a second conduit extending to said exhaust system upstream of said converter, said second conduit being a means for communicating said second outlet port with said exhaust system; and switching means, coactive with said change-over valve means, for providing selective communication between said inlet port of said change-over valve means and said first and second outlet ports in accordance with the temperature of said catalytic converter, said change-over valve means diverting air from said first outlet port to said second outlet port.

Claim 3

The improvement according to claim 1 wherein said first conduit includes a flow control valve means which permits a part of the exhaust gas in said exhaust system to recirculate to said intake system when said second outlet port is closed.

Claim 4

The improvement according to claim 1 further including a fan driven by the engine and in which a portion of said first conduit is in heat exchange relationship with the air flow of said fan.

Claim 5

In an automobile engine having an air intake system including an intake manifold, a catalytic converter, an exhaust system including an exhaust manifold and conduit means connecting said exhaust manifold to said converter, the improvement which comprises: a source of air under pressure; a change-over valve means having an inlet port communicating with said source, a first outlet port, a second outlet port, a valve seat at said first outlet port and having passages of large and small total cross section, and a valve member movable to close said large passages and maintain said small passages open, said change-over valve means selectively connecting said air source through said inlet port to said large passages or said second outlet port and said small passages; a first conduit connecting said first outlet port to said exhaust system upstream of said converter; a second conduit connecting said second outlet port to said intake system; means for controlling said change-over valve means to selectively connect said air source to said first outlet port and said second outlet port, said control means including a third conduit receiving atmospheric air, a fourth conduit connected to said intake system, a fifth conduit connected to said change-over valve means, and means connnecting said fifth conduit to said fourth conduit to control said change-over valve means with vacuum or to said third conduit to control said change-over valve means with atmospheric air; and means, responsive to an abnormality of an operating parameter of said converter and connected to said control means, to cause said control means to activate said change-over valve means to close said large passages and open said second outlet port and said small passages to said air source.

Claim 6

In an automobile engine having an air intake system including an intake manifold, a catalytic converter, an exhaust system including an exhaust manifold and conduit means connecting said exhaust manifold to said converter, the improvement which comprises: a source of air under pressure; a change-over valve means having an inlet port communicating with said source, a first outlet port, a second outlet port, a valve seat at said first outlet port and having passages of large and small total cross section, and a valve member movable to close said large passages and maintain said small passages open, said change-over valve means selectively connecting said air source through said inlet port to said large passages or said second outlet port and said small passages; a first conduit connecting said first outlet port to said exhaust system upstream of said converter; a second conduit connecting said second outlet port to said intake system; means for controlling said change-over valve means to selectively connect said air source to said first outlet port and said second outlet port, said control means including a third conduit receiving atmospheric air, a fourth conduit connected to said intake system, a fifth conduit connected to said change-over valve means, and means connnecting said fifth conduit to said fourth conduit to control said change-over valve means with vacuum or to said third conduit to control said change-over valve means with atmospheric air; and means, responsive to an abnormality of an operating parameter of said converter and connected to said control means, to cause said control means to activate said change-over valve means to close said large passages and open said second outlet port and said small passages to said air source.