Abstract: A diaphragm pump including an eccentric circular cam or crank shaft, a connecting rod rotatably connected at one end to the eccentric circular cam or crank shaft, a pair of diaphragms each having one surface serving as pressure receiving surface, center disks mounting the central portions of the pair of diaphragms on the opposite sides thereof, a first housing cooperating with one of the diaphragms and the center disks to define a first discharge chamber, a second housing cooperating with the other of the diaphragms and the center disks to define a second discharge chamber, a third housing cooperating with the pair of diaphragms and the center disks to define a suction chamber, a connecting member connecting the other end of the connecting rod to the center disks in the radial center and in the middle of the thickness thereof in order to minimize any swinging movement of the center disks which would otherwise be caused by reciprocatory swinging movement of the connecting rod, and guide means for guiding the c

Abstract: 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.

Abstract: 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.

Abstract: A diaphragm is interposed between first and second housings to form first and second diaphragm chambers at both sides thereof for pumping out air in accordance with expansion and contraction of the chambers. A shaft for reciprocally moving the diaphragm is connected thereto at one end and extends through a hole formed in a bushing which is fixed to the second housing. A lever is pivotally secured to the housing to perform a pivotal movement and operatively connected at its inner end to the other end of the shaft in a lever compartment of the housing and at its outer end to an eccentric cam formed on an engine crankshaft, so that the motion of the cam is transmitted to the shaft as the reciprocal movement through the pivotal movement of the lever. A bellows is disposed in the second diaphragm chamber surrounding a portion of the shaft, wherein the upper and lower ends are respectively and air-tightly connected to the diaphragm and the bushing to form a bellows chamber.

Abstract: In a system comprising a diaphragm type control valve with a diaphragm and a pair of chambers divided by the diaphragm, a plurality of orifices connecting the chambers and a thermo sensitive valve, the valve opening or closing period of the diaphragm type control valve is changed longer or shorter by opening and closing a bypass passage around one of the orifices by the thermo sensitive valve in response to temperature relative to the engine operating condition, whereby exhaust gas purification is attained with complete prevention of afterburn.

Abstract: A check valve has a valve member seated on a separating wall member in a housing to interrupt the flow of fluid. The valve member is formed to be unseated from the separating wall member in its free state so that the fluid may flow through a clearance between the valve member and the separating wall member when the pressure difference between one side of the separating wall member and the other is small, while it is formed to be seated on the separating wall member when the pressure difference has become larger. Therefore, the fluid can pass in the both directions crossing the separating wall member when the pressure difference is small, while it is interrupted when the pressure difference has increased.