Abstract: Disclosed is an exhaust gas cleaning apparatus of an internal combustion engine, provided with a three-way catalytic converter and a vacuum-operated flow control valve. The flow control valve has a diaphragm for controlling the amount of secondary air directed into an exhaust manifold of the engine for the effective operation of the three-way catalytic converter. In order to move the diaphragm to increase or decrease the amount of secondary air, a vacuum chamber is formed on one side of the diaphragm. This vacuum chamber is opened to a vacuum port formed in the intake system of the engine for transmitting the vacuum signal from the port to the vacuum chamber. Further, in order to maintain a constant rate of movement of the diaphragm irrespective of the vacuum level at the port, means are provided for transmitting a vacuum signal from the port to another vacuum chamber formed on the other side of the diaphragm.

Abstract: A system for returning part of exhaust gases from an internal combustion engine through a return passage into an intake passage. Provided in the return passage are a fixed orifice, a pressure chamber downstream thereof, and a regulating valve downstream of the chamber. The regulating valve controls the pressure in the pressure chamber for a proper flow rate of exhaust gases being returned or recirculated. An opening of the regulating valve is so designed as to respond to the movement of a pilot valve provided separately.

Abstract: Disclosed is a variable venturi type carburetor comprising a movable suction piston. The suction piston has a needle entering into a stationary jet. The needle and the jet defines an annular opening through which the fuel is injected into the intake passage formed in the carburetor. The jet is connected to a fuel reservoir via a fuel supply passage. The fuel reservoir is connected to the intake passage located downstream of the needle.