| 摘要 |
<p>A fuel injection pump for a diesel engine comprising a housing (1) with a fuel inlet (4); a transfer pump (2) mounted within the housing (1) and adapted to be driven by the engine to pump fuel from the fuel inlet (4) into the housing (1); a pressure-regulating valve (5) that controls the transfer pressure of fuel within the housing (1) produced by the transfer pump (2) and which has a fuel leakage path into a pressure control chamber (20), the pressure of which controls the setting of the pressure-regulating valve (5) to vary the transfer pressure; a high pressure pump and distributor (3) mounted within the housing (1) and adapted to be driven by the engine to deliver fuel at high pressure from the housing (1) to each of a plurality of fuel outlets (6) in sequence; a hydraulic timing device (10) comprising a resiliently loaded piston (11) responsive to the transfer pressure and which is linked to the high pressure pump and distributor (3) so as to advance the dynamic injection timing of the pump with increasing engine speed; a pressure relief valve (22) connected between the pressure control chamber (20) of the pressure-regulating valve (5) and the fuel inlet (4) to control the pressure in the pressure control chamber (20); and a cold condition actuator (26) having a hot operating state for hot engine conditions in which it opens the pressure-relief valve (22) to connect the pressure control chamber directly to the fuel inlet pressure, and a cold operating state for cold engine conditions in which it allows the pressure-relief valve (22) to operate and produce a back-pressure in the pressure control chamber (20); characterized in that the hydraulic timing device (10) includes restraining means (27) which when the cold condition actuator (26) is in the cold operating state becomes effective at a predetermined transfer pressure, corresponding to a required degree of advance dynamic injection timing, and restrains further movement of the resiliently-loaded piston (11) over a predetermined range of higher transfer pressure.</p> |
