US 5,507,262 AGranted

Control apparatus for internal combustion engine with exhaust gas recirculaton

AssigneeNippondenso Co., Ltd.

InventorsDaiji Isobe, Kiyoji Tara

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Abstract

In a mechanical type EGR apparatus, an EGR valve receives a negative pressure near a throttle valve and opens/closes an EGR path in response to the negative pressure. An EGR-VM is operated in response to an exhaust gas pressure to control a diaphragm back pressure to be introduced into the EGR valve. A CPU calculates a control amount of an ISC valve in order to obtain an optimum EGR ratio characteristic, depending upon engine operation conditions, and drives the ISC valve based on this control amount. The negative pressure at the negative pressure around the throttle valve is changed when the ISC valve is opened/closed and thus a portion of air into the engine flows through a bypass path, so that the diaphragm back pressure into the EGR valve is controlled to a desired value.

Claims7

Dependent claims

A control apparatus for an internal combustion engine with an exhaust gas recirculation, said apparatus comprising:

a recirculation path for recirculating a portion of an exhaust gas of an exhaust path of an internal combustion engine into an air intake path of the internal combustion engine;
an exhaust gas recirculation control valve for receiving a negative pressure from a negative pressure conducting port provided in the air intake path near a throttle valve, and for opening and closing the recirculation path in response to the negative pressure;
a negative pressure control valve for controlling the negative pressure from the negative pressure conducting port to the exhaust gas recirculation control valve in response to a pressure of the exhaust gas from the exhaust gas path;
a bypass path formed in the air intake path for bypassing the throttle valve and the negative pressure conducing port;
an idle revolution speed control valve formed in the bypass path for controlling an amount of auxiliary air to the internal combustion engine during an idle operation of the internal combustion engine;
a three-way valve for releasing and communicating a negative pressure path between the negative pressure conducting port and the exhaust gas recirculation control valve;
first control means for releasing the negative pressure path by using the three-way valve into the air and for driving the idle revolution speed control valve in order to control the idle revolution speed to a desired value during the idle operation of the internal combustion engine;
and
second control means for communicating the negative pressure path by the three-way valve and for driving the idle revolution speed control valve in order to control the negative pressure at the negative pressure conducting port during an exhaust gas recirculation operation different from the idle operation.

6 more elements

A control apparatus for an engine having an exhaust path and an intake path with a throttle valve, said apparatus comprising:

a recirculation path connecting the exhaust path and the intake path for recirculating an exhaust gas from the exhaust path to the intake path;
a recirculation control valve disposed in the recirculation path and controlling flow of the exhaust gas therethrough in response to a negative pressure at around the throttle valve in the intake path;
a bypass path connecting an upstream and a downstream of the throttle valve in the intake path bypassing the throttle valve;
an idle control valve disposed in the bypass path and controlling flow of a bypass air in the bypass path;
first control means controlling, in closed-loop manner, the idle control valve in response to a deviation of an actual engine speed from a target engine speed when the engine is in an idling condition;
and
second control means controlling the idle control valve in response to engine operating conditions irrespectively of the target engine speed when the engine is in an exhaust gas recirculation condition different from the engine idle condition.

4 more elements

Dependencies are inferred from the claim text.