Nippondenso Co., Ltd.

Toyota Jidosha Kogyo Kabushiki Kaisha

Motohisa Miura

Mikiji Ito

Hidetaka Nohira

Masaaki Tanaka

Shojiro Nagano

Noboru Matsumoto

Naohiro Naganuma

Yukihiko Muramatsu

Zyunziro Yoshimura

A control valve is mounted on an air relief line branched off from a secondary air supply line extending from an air pump to an exhaust pipe for controlling the pressure of air in the secondary air supply line. The control valve so controls the pressure of the air in the air supply line as to increase it when acceleration of an engine starts or to decrease it when deceleration of the engine starts, whereby the amount of the secondary air supplied to the exhaust pipe is controlled in response to the acceleration and deceleration of the engine.

Secondary air supply system for internal combustion engines

An engine exhaust gas purification system includes an EGR line for the recirculation of exhaust gases from an engine exhaust system back into an intake system thereof. An EGR valve is provided in the EGR line to control the rate of EGR. The EGR valve is actuated by an actuator which is operated by pressurized air supplied by a diaphragm pump driven by the engine in proportion to the engine speed. The pressure of the pressurized air is substantially proportional to the engine speed, whereby the EGR rate is controlled so as to be substantially proportional to the engine speed.

Exhaust gas purification system for an internal combustion engine

A secondary air supply control apparatus for an internal combustion engine comprises an air pump for producing the secondary air flow, a secondary air supply passage leading to an exhaust system of the engine, a bypass passage leading to the atmosphere, and a valve element connected to a diaphragm. The diaphragm constitutes one wall of a pressure chamber which is supplied with a negative intake pressure prevailing in an intake system of the engine, so as to move the valve element to a position at which the secondary air flow is directed to the secondary air supply passage when the negative intake pressure is higher than a predetermined level. There is provided a control unit operable in response to the pressure of the secondary air flow supplied to the exhaust system to apply the atmospheric pressure to the pressure chamber, thereby moving the valve element to another position at which the secondary air flow is directed to the bypass passage when the pressure of the secondary air flow supplied to the exhaust system is increased beyond a level which imposes overload on the air pump.

Secondary air supply control apparatus for internal combustion engine

An air switching valve for controlling supply of secondary air to an exhaust system of an engine closes an air release port thereof to increase an amount of secondary air to be supplied at least at an initial stage of an engine acceleration operation. The air switching valve closes a secondary air supply line to stop the supply of the secondary when the engine acceleration operation continues for more than a predetermined time period, thus to prevent an exhaust gas purifier disposed in the exhaust system from over-heat.

Secondary air supply system for an internal combustion engine

A system for controlling secondary air supply from an engine-driven air pump through a supply line into the engine exhaust manifold has a control valve with air inlet and outlet ports and a slidable, spring-biased valve seat member defining main and auxiliary air release openings. A first valve member is movable by a valve actuator to control the communication between the air inlet and outlet ports and the main air release opening. A second valve member is resiliently urged by a second spring against the valve seat member to control the communication between the auxiliary air release apertures in the valve seat member and the air release port. The valve actuator has first and second air pressure chambers connected to the secondary air supply line upstream of the secondary air control valve. The first control chamber is connected to the engine intake system. Control valves are provided to control the supply of air pressure into the first and second chambers such that, at least at the initial stage of an engine acceleration, the air release pressure at which the second valve member is moved away from the valve seat member to permit release of the secondary air is increased with resultant increase in the secondary air supply to the engine exhaust system. Pressure delay valves are provided for the control valves whereby the secondary air supply is interrupted when acceleration has lasted for more than a predetermined time.

A relief pressure control valve for controlling the pressure in a secondary air supply line has first and second pressure chambers divided by a diaphragm, a spring for biasing the diaphragm towards the second pressure chamber, a relief port connected to the secondary air supply line, a valve head connected to the diaphragm and being biased to close the relief port. The air pumped out from an air pump is supplied to the first pressure chamber and the first pressure chamber is communicated with the second pressure chamber through an orifice. Accordingly, during stable running operations of the engine, the pressures in the first and second pressure chambers are made equal by means of the orifice, while during the accelerations pressure difference is produced between the chambers for a certain time period. The pressure difference urges the diaphragm in the same direction as that of the urging force of the spring, whereby the pressure in the secondary air supply line controlled by the relief pressure control valve is increased during the accelerations so as to supply the increased amount of the secondary air to the exhaust pipe of the engine.

An exhaust gas control valve comprising a diaphragm interposed between an outer upper casing and an outer lower casing of the diaphragm housing, the diaphragm and the upper outer casing defining a first pressure chamber, an inner upper casing attached to the upper surface of the diaphragm within the first pressure chamber, an inner lower casing attached to the undersurface of the diaphragm within the outer lower casing, the inner lower casing and the diaphragm defining a second pressure chamber, a valve housing attached to the bottom of the diaphragm housing and provided with an exhaust gas intake port, an exhaust gas discharge port and a valve seat member disposed in a passage between the exhaust gas intake and discharge ports, a valve head with a stem whose upper end is attached to the center of the diaphragm so that the valve head may be moved toward and away from the valve seat member depending upon the deflection of the diaphragm, the space or chamber defined by the diaphragm and the inner upper casing and the space or chamber defined by the diaphragm and the outer lower casing being communicated with the surrounding atmosphere, and the different negative pressures being transmitted to the first and second pressure chambers, respectively, whereby the quantity of exhaust gases to be recirculated may be controlled depending upon the operating conditions of the engine to minimize the nitrogen oxide (NOx) emission.

Exhaust gas control valve

An exhaust gas control valve adapted for controlling exhaust gas flow returning to the upstream side of a carburetor from an exhaust line of a vehicle engine. The control valve comprises a means for reducing or stopping the returning exhaust gas when ambient temperature is very low, whereby so called carburetor icing is avoided.

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Toyota, Japan

Motohisa Miura