Patent ID: 6845754
Filing Date: 2005-01-25
Classification: F02M

Abstract:
1. A device for injecting fuel into a combustion chamber of an internal combustion engine comprising: a fuel inlet through which fuel is introduced into the device; a fuel outlet through which fuel is injected from the device; a first control valve operable selectively to open the fuel outlet for allowing fuel to be injected from the device and to close the fuel outlet for disallowing fuel from being injected from the device; a plunger operable within a pumping chamber that has fluid communication with both the fuel inlet and the first control valve for executing a charge stroke to fill the pumping chamber with fuel from the fuel inlet while the first control valve is closed, and thereafter a discharge stroke that forces fuel from the pumping chamber to open the first control valve to the fuel outlet and be injected from the fuel outlet; a control fluid inlet at which control fluid, other than fuel, is introduced into the device; a second control valve that is operable selectively to a first position to cause control fluid to force the first control valve closed and thereby disallow injection of fuel from the fuel outlet and to a second position to disallow control fluid from forcing the first control valve closed and thereby cause injection of fuel from the fuel outlet; and a third control valve that is operable selectively to allow control fluid to force the plunger to execute a discharge stroke while the second control valve is disallowing control fluid from forcing the first control valve closed and to disallow control fluid from preventing execution of a charge stroke; wherein the first control valve comprises three ports, a first of which is in fluid communication with the pumping chamber, a second of which forms the fuel outlet, and a third of which is in fluid communication with the second control valve, a spring that resiliently biases a movable valve element toward seating on a seat that circumscribes the second port in closure of the fuel outlet, and wherein control fluid that the second control valve allows to force the first control valve closed is communicated to the third port of the first control valve to force the movable valve element toward seating on the seat, the movable valve element comprises a first surface on which control fluid communicated to the third port of the first control valve acts to force the movable valve element toward seating on the seat and a second surface on which fuel that is communicated to the first port of the first control valve acts to urge the movable valve element away from seating on the seat, wherein the first surface of the movable element comprises an effective area larger than an effective area of the second surface and is disposed within a chamber within which the spring is also disposed to bear against the first surface for resiliently biasing the movable valve element toward seating on the seat, and a fluid passage that extends from the second control valve to the chamber through which fluid passage control fluid is communicated to the first surface when the second valve control valve is in the first position and through which the control fluid that had been communicated to the first surface is drained when the second valve control valve is in the second position.