Patent ID: 6273066
Filing Date: 2001-08-14
Classification: F02M

Abstract:
In a fuel injection system for an internal combustion engine having a high-pressure pump for pumping fuel into a fuel reservoir and having at least one fuel injector connected to the reservoir by a feed line, the fuel injector having an injection nozzle and a movable nozzle needle therein to control flow therethrough and being fluidly connected to the feed line, a control piston in the fuel injector defining a control space at one end thereof fluidly connected to the feed line, the injection needle and control piston being operatively connected, a fuel bleed passage connected to the injector's control space, and a solenoid activated valve co-operative with the fuel bleed passage to selectively transmit pressurised fuel from the control space to a low-pressure fuel return when the bleed passage is opened, and further including a fuel inlet pressure regulating valve assembly between the reservoir and fuel injection to selectively vary the cross section of the flow connection from the reservoir to the injector for regulating fuel flow thereto, characterised in that: the pressure regulating valve assembly has a pressure regulating valve (20) movable in response to fuel pressure and a solenoid valve (33) adjacent one end of the pressure regulating valve (20) and which is operated independently of the injector's solenoid valve; the solenoid valve (33) being controlled to effect movements of said pressure regulating valve (20) which varies the cross section of the fuel passage from the reservoir to the injector in a way establishing a first position of the pressure regulating valve (20) corresponding to an injection phase when the solenoid valve (33) is closed during which a flow connection from the reservoir to the injector (4) is open, and a second position of the pressure regulating valve (20) corresponding to a phase just before an injection when the solenoid valve (33) is opened during which the flow connection from the reservoir to the injector (4) is closed but a flow connection from the injector (4) to a low-pressure side of the pump is open, and a third position of said pressure regulating valve (20) corresponding to a phase just prior to the start of injection when the solenoid valve (33) is closed during which the flow connection from the reservoir to the injector (4) is opened in coordination with opening of the injector's solenoid valve (7).