Hitachi, Ltd.

Tomo Ito

Torazo Nishimiya

Chiaki Niida

Masamitsu Okumura

Seisaku Numakura

Masamitsu Asakura

A suction pipe is provided to suck and introduce air from its one end and is connected at its other end to an internal combustion engine. The suction pipe is provided at its one end with a venturi portion and a throttle valve. A first negative pressure detector is provided to detect the negative pressure at the portion of the suction pipe remote from the internal combustion engine, so as to sense a comparatively gentle pressure rise in the suction pipe. A control valve is provided to be opened and closed in accordance with the output from the first negative pressure detector, thereby to control the flow rate of air supplied into the suction pipe. A second negative pressure detector is provided to detect the negative pressure at a portion of the suction pipe remote from the internal combustion engine, so as to sense an abrupt increase of the negative pressure in the suction pipe. This second negative pressure detector is disposed between the first valve and the first negative pressure detector and adapted to produce an output in accordance with which the first valve is controlled.

Device for controlling negative pressure in suction pipe of internal

An exhaust gas recirculation control system for controlling the amount of exhaust gas subjected to recirculation to the air inlet depending on the amount of inlet air of an internal combustion engine. This system comprises a control valve disposed in an exhaust gas recirculation passage, for controlling the amount of exhaust gas recirculation, an orifice disposed in the recirculation passage, for creating a negative pressure upstream of the control valve, and a solenoid valve for generating a pressure which controls the control valve. The solenoid valve comprises a core formed therein with a hollow passage opened at one end to a valve portion, a plunger made of a magnetic material and having a valve seat opposing the open end to define the valve portion, a spring biasing the plunger in the opening direction of the valve portion, a first exciting coil generating, when passing therethrough a current proportional to the amount of inlet air, a force acting on the plunger to close the valve portion, and a second exciting coil generating, when passing therethrough a current in inverse proportion to the pressure downstream of the orifice, a force opposite to the force on the plunger due to the first exciting coil.

Exhaust gas recirculation control system for internal combustion engine

A vacuum operated servo comprises a vacuum chamber defined by a flexible diaphragm and a cover, a valve seat secured to the cover so as to project into the vacuum chamber, a valve body yieldably mounted on the flexible diaphragm, a first vacuum conduit with a first valve for inducing vacuum from a vacuum source into the vacuum chamber through the valve seat, a second vacuum conduit with a second valve for inducing vacuum from the vacuum source into the vacuum chamber, and a leak orifice for leaking the vacuum in the vacuum chamber. When the first valve is opened to induce vacuum of the vacuum source into the vacuum chamber, by the vacuum, the diaphragm is moved so that the valve body contacts with the valve seat. Upon the contact, the induction of the vacuum is interrupted to stop the movement of the diaphragm, with the vacuum being introduced and leaked out of the vacuum chamber. When the second valve is opened to induce the vacuum of the vacuum source into the vacuum chamber, the vacuum moves the diaphragm to contact a stopper provided on the diaphragm with the cover irrespective of operation of the first valve. Therefore the vacuum operated servo provides a plurality of positions.

Vacuum operated servo

A dashpot with a fast idle device for carburetor throttles comprises a dashpot for damping a rapid closing movement of the throttle and a fast idle device for causing an automobile to run at fast idle. The fast idle device has a vacuum chamber separated from an air chamber of the dashpot by a partition, and a rod passing through a hole made in the partition, which rod is secured to a diaphragm defining a part of the vacuum chamber and axially moved with vacuum induced into the vacuum chamber. For sealing a gap defined between the rod and the partition, there is provided with a resilent seal member which is disposed in the air chamber of the dashpot and comprises a first portion engaged with an annular groove made in the rod so that the first portion will move in conformity with the axial movement of the rod, a second portion disposed around the gap and airtightly contacting with the partition, and a third portion extending from the first portion to the second portion and having a shape such that the second portion is pressed on the partition more tightly with the vacuum increasing. The seal member is shaped for example like a cup.

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Katsuta, Japan

Tomo Ito