Patent ID: 6422212
Filing Date: 2002-07-23
Classification: F02M,Y10T

Abstract:
In an on-off valve (16) for use in a fuel injection system (10) for internal combustion engines, the system housing a low-pressure pump (11) for withdrawing fuel from a tank (18) and a high-pressure pump (12) that is supplied by the low-pressure pump (11) and camshaft-actuated pump elements (23), wherein the on-off valve (16) has a sleeve-shaped valve piston (34), which can be longitudinally moved by the pressure of the low-pressure pump (11) and is loaded by a prestressed helical compression spring (35), has a throttle bore (54) in the piston bottom (53) and, at a predetermined pressure threshold of the fuel delivered by the low-pressure pump (11), opens an outlet bore (48) in a valve housing (32) that guides the piston (34), wherein the throttle bore (54), on its outlet side, continuously communicates with a chamber (25), which contains the camshaft (24) and belongs to a housing (26) of the high-pressure pump (12), which chamber is connected to the fuel tank (18), the improvement wherein, at a first pressure threshold, the valve piston (34) controls a connection (49, 55, 57, 45, 47) extending parallel to the throttle bore (54), between the low-pressure pump (11) and the camshaft chamber (25) of the high-pressure pump (12), and at a relatively higher second pressure threshold, opens the outlet bore (48) which communicates directly with the suction side of the low-pressure pump (11).