CONTROL VALVE ASSEMBLY FOR PUMPS AND INJECTORS

摘要

A control valve assembly for use in a pump or injector of fuel injection valves is provided. A pump (10) or injector body has a pumping chamber (16), and a valve chamber (22). The valve chamber (22) defines a valve seat (72) a nd has an axial guiding portion. A plunger (30) is disposed in the pumping chamber (16). A valve body (48) disposed in the valve chamber controls fuel. The valve body (48) has a valve stem defining a seating surface. The valve body further has a valve guide in sliding engagement with the valve chamber guiding portion. The valve body is axially movable with respect to the valve chamber over a stroke range. The valve guide has an outer engagement surface that slidingly engages the valve chamber guiding portion with a clearance fi t of at least about 5 micrometers in one embodiment. In another embodiment, th e axial length of the engagement surface is at most about 7 millimeters. The reduced axial length and/or the clearance fit improve initial sealing performance and sealing performance over the life cycle of the product.