EXHAUST GAS RECIRCULATION VALVE

摘要

An EGR valve includes a housing formed with a passage, a valve seat provided in the passage, a valve element seatable on the valve seat, a valve stem provided with the valve element at an end, and an actuator for making stroke movement of the valve stem. The valve element is moved together with the valve stem with respect to the valve seat to change an open area of a measuring section, thereby changing an opening degree of the valve element, to adjust a flow rate of EGR gas in the passage. The EGR valve has high-resolution flow-rate characteristics in a low opening region of the valve element and large flow-rate characteristics in a high opening region. The valve element and the valve seat have predetermined shapes to cause the flow-rate characteristics in the low opening region to change in a curve without a step.

主权项

1. An exhaust gas recirculation valve including:
a housing including a passage for exhaust recirculation gas; a valve seat provided in the passage, the valve seat having a valve hole including an inner circumferential surface, the inner circumferential surface including an upstream-side inner circumferential edge and a downstream-side inner circumferential edge; a valve element provided to be seated on the valve seat and configured to form a measuring section for the exhaust recirculation gas between the valve element and the valve seat, the valve element having a nearly umbrella shape and including a minimum-diameter portion and a maximum-diameter portion; and a valve stem having an end portion at which the valve element is provided, the valve element being placed inside the valve hole and provided to be movable together with the valve stem between a fully closed position where a portion of the valve element near the maximum-diameter portion is in contact with the upstream-side inner circumferential edge of the valve hole and a fully open position where the maximum-diameter portion is disposed farthest from the upstream-side inner circumferential edge in an axial direction of the valve seat, wherein the exhaust gas recirculation valve is configured to move the valve element together with the valve stem with respect to the valve seat to change an open area of the measuring section and change an opening degree of the valve element to adjust a flow rate of the exhaust recirculation gas in the passage, and the valve has flow-rate characteristics of high resolution in a low opening region of the valve element and flow-rate characteristics of large flow rate in a high opening region, and wherein the valve element and the valve seat have predetermined shapes to cause the flow-rate characteristics in the low opening region to change in a curve without a step.