Exhaust gas recirculation apparatus for an internal combustion engine

Claim 2

An exhaust gas recirculation apparatus comprising conduit means connecting the exhaust system of an engine to the intake system thereof at a first location downstream of the throttle valve of the engine and a second location upstream of said throttle valve, normally closed valve means in said conduit means to control flow from said exhaust system to said first and second locations, at least one of said valve means having a closed chamber with a diaphragm therein normally resiliently biasing a valve part to closed position and means to connect said closed chamber to a port located slightly above the fully closed position of said throttle valve whereby vacuum from said port may cause said diaphragm to move said valve part to opening position against said resilient bias and means to cause an effect of said vacuum to open the other of said valve means.

Claim 3

An exhaust gas recirculation apparatus for an internal combustion engine, comprising: a first conduit for recirculating the exhaust gas from the exhaust system of the engine to the intake system of the engine in a first location downstream of a throttle valve of the engine, a first valve in said first conduit, said valve having a spring biased vacuum responsive diaphragm to control it, means connecting said diaphragm to a vacuum port located slightly above the fully closed position of said throttle valve, and; a second conduit for recirculating the exhaust gas from said exhaust system to said intake system to a second location upstream of said throttle valve, a second valve in said second conduit, said second valve having a spring biased vacuum responsive diaphragm to control it, means connecting said diaphragm of said second valve to said vacuum port whereby exhaust gas of a sufficient amount can be recirculated during a light and a medium load operation of the engine to reduce the amount of NO x emission from the engine, whereas exhaust gas of a minimum amount can be recirculated during a heavy load operation to prevent adverse effects to said heavy load operation.

Claim 4

An exhaust gas recirculation apparatus for an internal combustion engine, comprising: a first conduit for recirculating the exhaust gas from the exhaust system of the engine to the intake system of the engine in a first location downstream of a throttle valve of the engine, a first valve in said first conduit, said valve having a spring biased vacuum responsive diaphragm to control it, means connecting said diaphragm to a vacuum port located slightly above the fully closed position of said throttle valve, and; a second conduit for recirculating the exhaust gas from said exhaust system to said intake system to a second location upstream of said throttle valve, a second valve in said second conduit, said second valve having a spring biased vacuum responsive diaphragm to control it, means connecting said diaphragm of said second valve to said vacuum port whereby exhaust gas of a sufficient amount can be recirculated during a light and a medium load operation of the engine to reduce the amount of NO x emission from the engine, whereas exhaust gas of a minimum amount can be recirculated during a heavy load operation to prevent adverse effects to said heavy load operation.

Claim 5

An exhaust gas recirculation apparatus according to claim 2, further comprising: a first flow control orifice arranged in said first conduit located downstream of the first diaphragm control valve, and; a second flow control orifice arranged in said second conduit located downstream of the second diaphragm control valve, whereby a predetermined shape of a characteristic curve showing the proportion of recirculated gas versus the degree of throttle opening is possible by adjusting the dimensions of said first and second orifices.

Claim 6

An exhaust gas recirculation apparatus for an internal combustion engine, comprising: a first conduit for recirculating the exhaust gas from the exhaust system of the engine to the intake system of the engine in a first location downstream of a throttle valve of the engine, a diaphragm control valve in said first conduit, means connecting said valve to a vacuum port located slightly above the fully closed position of said throttle valve, and; a second conduit downstream of said diaphragm control valve for recirculating exhaust gas from said exhaust system to a second position of said intake system upstream of said throttle valve, a check valve located in said second conduit which is opened by the recirculating exhaust gas when said diaphragm valve is open.

Claim 7

An exhaust gas recirculation apparatus for an internal combustion engine, comprising: a first conduit for recirculating the exhaust gas from the exhaust system of the engine to the intake system of the engine in a first location downstream of a throttle valve of the engine, a diaphragm control valve in said first conduit, means connecting said valve to a vacuum port located slightly above the fully closed position of said throttle valve, and; a second conduit downstream of said diaphragm control valve for recirculating exhaust gas from said exhaust system to a second position of said intake system upstream of said throttle valve, a check valve located in said second conduit which is opened by the recirculating exhaust gas when said diaphragm valve is open.

Claim 8

An exhaust gas recirculation apparatus according to claim 4, further comprising: a first flow control orifice arranged in said first conduit located downstream of the first diaphragm control valve, and; a second flow control orifice arranged in said second conduit located downstream of said check valve whereby a predetermined shape of a characteristic curve showing the proportion of recirculated gas versus the degree of throttle opening is obtained by adjusting the dimensions of said first and second orifices.