Nissan Motor Company Limited

Syunichi Aoyama

Yasuo Nakajima

Yoshimasa Hayashi

Yasuo Takagi

Kunihiko Sugihara

Kazuo Hioki

A valve lift control apparatus for an internal combustion engine, characterized by a hydraulic valve lifter constructed and arranged so that the motion of the cam for driving the intake or exhaust valve in each power cylinder is transmitted through the valve lifter to the valve without intervention of any axially abutting engagement between the movable members of the valve lifter by the fluid pressures intervening between the individual movable members. The valve lift control apparatus may further comprise a fluid pressure control device for varying the fluid pressure to be supplied to a hydraulic valve lifter in relation to certain operational conditions of the engine.

Hydraulic valve lifter and fluid pressure control device therefor

A hydraulic valve lifter useful for but not limited to an automotive internal combustion engine of the overhead camshaft type, comprising two rockable members one of which is in engagement with the cam on the engine camshaft and the other of which is in engagement with the intake or exhaust valve of a power cylinder of the engine, wherein the two rockable members are pivotable about a common axis either as a single unit or independently of each other for taking up the clearance in the valve train to a degree which is continuously variable with prescribed operational conditions of the engine.

Hydraulic valve lifter

A hollow cylinder is slidably received in a bore formed through an engine block with its closed end in contact with a lobed cam mounted on a camshaft, and a piston connected to a push rod is received in an end portion of the bore. A plunger disposed in the bore partly intrudes into the cylinder so as to define a first oil pressure chamber in the cylinder and a second oil pressure chamber between the plunger and the piston. When oil pressure applied to the first chamber is decreased as the engine speed lowers, the plunger moves toward the first chamber to allow the second chamber to communicate with an oil-reserving chamber through a hole. The amount of valve lift in a medium oil pressure range depends on the degree of closing of this hole by the plunger which is moved together with the cylinder by the rotating cam.

Hydraulic valve lifter mechanism for internal combustion engine

An engine is equipped with an EGR system in which the amount of recirculated exhaust gases is controlled in response to an intake vacuum in an intake passage. The spark timing of the engine is controlled to advance in accordance with the increase of the amount of the recirculated exhaust gases so as to maintain stable engine running even under a considerably high EGR rate.

Spark advance control device for engine equipped with EGR system

A restriction is formed in a branch passage of the exhaust gas passageway of an engine having a plurality of combustion chambers, which passage communicates at its upstream end with only a part of the combustion chambers of the engine, to divide the branch passage into upstream and downstream sections, and the EGR passageway connects the upstream section and the induction passageway of the engine, and the EGR rate is controlled by controlling a vacuum for operating the EGR control valve in accordance with the pressure differential between the upstream and downstream sections and/or a venturi vacuum to control the degree of opening of the EGR control valve and therefore the pressure differential between the sections and therefore the flow rate of exhaust gases passing through the restriction.

Engine exhaust gas recirculation control system

An exhaust gas recirculation system comprises a valve assembly for controlling the recirculation of exhaust gases in such a manner as to maintain a difference between a first and second pressure at a predetermined value. The first pressure is a pressure in a zone in an air induction passage between a throttle valve therein and a flow restrictor disposed therein downstream of the throttle valve, while the second pressure is a pressure in a zone in an exhaust gas recirculation passage between an exhaust gas recirculation flow control valve member and a second flow restrictor disposed therein downstream of the valve member.

Exhaust gas recirculation system

An EGR control system consists of a pressure regulating valve assembly which functions to prepare a control vacuum for an EGR control valve in accordance with the relationship between venturi vacuum and the pressure in a particular part of an EGR passageway connecting an exhaust gas passageway to an intake passageway. A connecting passage connecting the particular part of the EGR passageway to the pressure regulating valve assembly is provided with a flow restricting orifice therein. The connecting passage is further provided with a check valve to induct atmospheric air into the connecting passage to clean up the flow restricting orifice.

EGR Control system

An altitude correction device is provided which adjusts a working vacuum, in the diaphragm unit for operating the EGR control valve, in accordance with the atmospheric pressure so as to reduce the flow of recirculated engine exhaust gases in accordance with decrease in the atmospheric pressure to maintain the EGR amount at a proper value independent of the altitude.

Exhaust gas recirculation control system

An EGR control valve is closably disposed in an EGR passageway connecting an intake passageway and an exhaust gas passageway which leads to an internal combustion engine. The EGR control valve is operated to control recirculated exhaust gas flow by varying the exhaust gas pressure in a chamber between a restriction disposed in the EGR passageway and the EGR valve, in accordance with variations in a venturi vacuum in the intake passageway to prevent the recirculated exhaust gas flow from being affected by the exhaust gas pressure in the EGR passageway upstream of the chamber. Furthermore, the EGR control valve is arranged to be controlled so that the amount of the recirculated exhaust gas flow is reduced during high engine speed and low load engine operation.

An EGR (Exhaust Gas Recirculation) control system comprises EGR control valve means including a first fluid chamber the vacuum in which increases and decreases in accordance with operating conditions of the engine whereby EGR control valve means control the recirculated amount of exhaust gases back to the engine and a second fluid chamber receiving therein a suction vacuum to thereby cause multiplication of the vacuum in the first chamber without altering the correspondency between the operating condition of the engine and the degree of opening of the EGR control valve means whereby the variable range of the vacuum in the first fluid chamber is optimally enlarged. An EGR control system further comprises relief valve means for reducing the EGR ratio below a predetermined constant level upon high speed low load operating condition of the engine and which includes a fluid chamber directly communicating with the first fluid chamber of the EGR control valve means whereby the relief valve means is operated by the vacuum substantially equal to the vacuum in the first fluid chamber of the EGR control valve means.

A multiple spark plug ignition internal combustion engine is equipped with an EGR control system which consists of an EGR control valve disposed in an EGR passageway connecting an exhaust gas passageway and an intake passageway. The EGR control system is arranged to control EGR rate in accordance with venturi vacuum and in accordance with the exhaust gas pressure in the EGR passageway upstream of the EGR control valve. The EGR control system comprises a device for decreasing the EGR rate under a suburban area cruising condition of a motor vehicle on which the engine is mounted.

Secondary air fed to the exhaust system of an engine is controlled by controllably venting the secondary air passing through a secondary air supply conduit leading to the exhaust system using a diaphragm unit operated valve. Vacuum applied to the diaphragm unit is controlled by cooperation of the venturi vacuum and the pressure differential between two interior portions of the secondary air supply conduit to supply the exhaust system with an appropriate amount of secondary air to the exhaust gas amount.

Secondary air supply device for engine exhaust system

An engine equipped with an electronically controlled fuel injection system is provided with an EGR control system which accurately regulates the EGR rate in accordance with a vacuum signal produced at a venturi formed in the intake passageway of the engine, under low and medium load engine operating conditions. However, under high speed and high load engine operating conditions, a part of intake air is bypassed through a bypass passage connecting the upstream and downstream sides of the venturi in order to prevent increase of the flow resistance of the intake air.

EGR Control system for internal combustion engines

Two diaphragms divide a vacuum motor which controls the flow of exhaust gases from the exhaust passage to the induction system into three chambers, the first is fed a modulated vacuum signal from the induction passage, the second either an uncontrolled signal from substantially the aforementioned part of the induction passage or a VC vacuum created immediately upstream of the position assumed by the throttle valve in a fully closed position and the third exposed to atmospheric pressure. A relief valve disposed in the conduit through which the modulated vacuum is fed opens upon the pressure therein falling to a predetermined level to further modulate the vacuum in the first chamber. The vacuum regulating device which modulates the vacuum from the induction passage is responsive to atmospheric pressure, a signal which originates immediately downstream of a restriction in the EGR passage which may be either greater or less than atmospheric pressure depending on the design of the restriction and a venturi vacuum signal or the equivalent. To modulate the vacuum in the first chamber the relief valve can feed the vacuum which opens it to a normally atmospheric chamber of the vacuum regulating device.

Control system for an exhaust gas recirculation system

An EGR control valve operating diaphragm unit operated by the difference between an exhaust gas pressure in a chamber interposed between the EGR control valve and a restriction provided in the EGR passageway upstream of the EGR control valve and a venturi vacuum in the engine intake passageway or a combination of an EGR control valve operating diaphragm unit operated by the difference between the atmospheric pressure and an engine suction vacuum and a pressure regulating valve controlling the flow of atmospheric air admitted for diluting the suction vacuum which diaphragm unit or combination operates the EGR control valve to reduce and increase the exhaust gas pressure in the chamber in the EGR passageway in accordance with increases and decreases in the venturi vacuum, respectively.

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Yokohama, Japan

Syunichi Aoyama