Auxiliary air control valve for engines

An auxiliary air control valve for engines comprising:

• a valve casing having an air inlet port and an air outlet port, the ports being connected to a bypass passage for a throttle valve in an intake passage to an engine;
• a temperature dependent type actuator which is housed in the valve casing, which cooling water to the engine is partly branched to be introduced to, and which is depending on the temperature of the cooling water;
• a valve seat which is arranged in the valve casing to divide its inside into an air inlet side and an air outlet side, and which has a valve seat port formed therein;
• an operating rod which is supported by the actuator so as to be axially movable, and which can be moved forwardly under temperature dependent operation of the actuator;
• a valve which is supported and can be moved forwardly by the operating rod, and which can have a forward end peripheral portion confronted with the valve port;
• and
• means which is arranged between a rear end of the valve and the valve seat to urge the valve backwardly;
• wherein the valve has an intermediate peripheral portion enlarged to present a small gap to the valve seat port, and the front side of the intermediate peripheral portion and the rear side thereof formed to have slant surfaces so as to be diametrically and gradually reduced so that when the cooling water is at a low temperature, the front slant surface is positioned at the valve seat port, when the cooling water is at an intermediate temperature, the intermediate peripheral portion is positioned at the valve seat port, and when the cooling water is at a high temperature, the rear slant surface is positioned at the valve seat port, thereby being capable of controlling the quantity of intake air through the bypass passage.