Internal combustion engine equipped with improved exhaust gas recirculation system

Claim 2

An internal combustion engine having a combustion chamber therein, comprising: an intake system including an intake passage for passing therethrough at least air to the combustion chamber of the engine; an exhaust system including an exhaust passage for passing therethrough the exhaust gases discharged from the combustion chamber; exhaust gas recirculating means for recirculating a portion of the exhaust gases passing through the exhaust system into the combustion chamber through the intake system, said exhaust gas recirculating means including conduit means connecting the intake system and the exhaust system, and control valve means disposed in said conduit means for controlling the amount of the exhaust gases passing therethrough by varying the opening degree of said control valve means in response to an engine operating parameter; and a constant area venturi portion disposed within a portion of said conduit means and spaced apart from said control valve means of said exhaust gas recirculating means, said venturi portion constituting part of a Laval nozzle which is capable of causing exhaust gases passing therethrough to flow at the velocity of sound when the pressure differential between the upstream and downstream sides thereof is within a predetermined range, said control valve means effective for control of exhaust gas flow when said pressure differential is without said predetermined range.

Claim 3

An internal combustion engine as claimed in claim 1, in which the lower limit of said predetermined range is a pressure of 100 mmHg.

Claim 4

An internal combustion engine as claimed in claim 1, in which said portion is located downstream of said control valve means.

Claim 5

An internal combustion engine as claimed in claim 1, in which said intake system further includes a carburetor connected to said intake passage.

Claim 6

An internal combustion engine as claimed in claim 4, in which said conduit means of said exhaust gas recirculating means connects said exhaust passage of the exhaust system to a portion of the intake system downstream of the throttle valve of said carburetor.

Claim 7

An internal combustion engine as claimed in claim 5, in which said control valve means includes a valve seat disposed inside of the conduit means, a valve head movably disposed within said conduit means and contactable with said valve seat, and a diaphragm actuator for actuating the valve head in response to a vacuum produced at a portion of the engine, including a diaphragm which is normally urged by a spring in the direction to cause said valve head to contact with said valve seat and movable in the direction to separate the valve head from the valve seat in response to the vacuum applied thereto, said valve head being connected to said diaphragm.

Claim 8

An internal combustion engine as claimed in claim 6, in which said valve seat has an opening therethrough, and said valve head is formed into a cone-shape and disposed insertable into the opening of said valve seat to be contactable with said valve seat.

Claim 9

An internal combustion engine as claimed in claim 6, in which said vacuum is an amplified venturi vacuum, the venturi vacuum being produced at the venturi portion of said carburetor.

Claim 10

An internal combustion engine having a combustion chamber therein, comprising: an intake system including an intake passage for passing therethrough at least air to the combustion chamber of the engine; an exhaust system including an exhaust passage for passing therethrough the exhaust gases discharged from the combustion chamber; exhaust gas recirculating means for recirculating a portion of the exhaust gases passing through the exhaust system into the combustion chamber through the intake system, said exhaust gas recirculating means including conduit means connecting the intake system and the exhaust system, and control valve means for controlling the amount of the exhaust gases passing therethrough by varying the opening degree of said control valve means in response to an engine operating parameter, said control valve means including a valve seat disposed inside of said conduit means, a valve head seatable on said valve seat, and a diaphragm actuator for actuating the valve head in response to a vacuum produced at a portion of the engine; and a constant area venturi portion disposed inside of a portion of said conduit means and spaced apart from the valve seat of said control valve means, said venturi portion constituting part of a Laval nozzle which is capable of causing exhaust gases passing therethrough to flow at the velocity of sound when the pressure differential between the upstream and downstream sides thereof is within a predetermined range, said control valve means effective for control of exhaust gas flow when said pressure differential is without said predetermined range.

Claim 11

An internal combustion engine having a combustion chamber therein, comprising: an intake system including an intake passage for passing therethrough at least air to the combustion chamber of the engine; an exhaust system including an exhaust passage for passing therethrough the exhaust gases discharged from the combustion chamber; exhaust gas recirculating means for recirculating a portion of the exhaust gases passing through the exhaust system into the combustion chamber through the intake system, said exhaust gas recirculating means including conduit means connecting the intake system and the exhaust system, and control valve means for controlling the amount of the exhaust gases passing therethrough by varying the opening degree of said control valve means in response to an engine operating parameter, said control valve means including a valve seat disposed inside of said conduit means, a valve head seatable on said valve seat, and a diaphragm actuator for actuating the valve head in response to a vacuum produced at a portion of the engine; and a constant area venturi portion disposed inside of a portion of said conduit means and spaced apart from the valve seat of said control valve means, said venturi portion constituting part of a Laval nozzle which is capable of causing exhaust gases passing therethrough to flow at the velocity of sound when the pressure differential between the upstream and downstream sides thereof is within a predetermined range, said control valve means effective for control of exhaust gas flow when said pressure differential is without said predetermined range.