Claims:We claim
1. A method for storing compressed fuel in a fuel pipe (3) that is coupled between a high pressure fuel pump (1) and a fuel injector (2), the method comprising:
connecting a first end of the fuel pipe (3) to an outlet of the high pressure fuel pump (1);
connecting an opposite second end of the fuel pipe (3) to a high pressure connector 4 of the fuel injector (2);
storing pressurized fuel within the fuel pipe (3) after the fuel injector (2) has finished delivering pressurized fuel to an engine; and
delivering pressurized fuel from the fuel pipe (3) to the fuel injector (2) during a subsequent injection event of the fuel injector (2).

2. A high pressure fuel pump (1), said high pressure fuel pump (1) comprising:
a pumping chamber;
a unidirectional flow control valve in flow communication between said pumping chamber and a fuel pipe (3), said unidirectional flow control valve adapted to supply pressurized fuel to said fuel pipe (3), said unidirectional flow control valve prevents pressurized fuel from said fuel pipe (3) from returning to said pumping chamber of said high pressure fuel pump (1). , Description:Field of the invention
[0001] This invention relates to a method for storing compressed fuel in a fuel pipe that is coupled between a high pressure fuel pump and a fuel injector.

Background of the invention
[0002] U.S. Patent Application Number US 4,884,545 describes a high pressure, continuous delivery piston pump, controlled as a function of engine speed and load, supplies fuel to an accumulator supplying injectors. On the intake side of the pump, there is provided a throttle for metering the amount of fuel supplied by the pump. Via operating signals, the throttle is regulated by an electronic control device in such a manner as to supply the pump and pressurize only the amount of fuel strictly required for operating the injectors and the engine, thus eliminating any energy losses caused by fuel feedback to the tank, and drastically reducing fuel consumption.

Brief description of the accompanying drawings
[0003] Figure 1 illustrates a high pressure fuel pump that supplies fuel to a fuel injector via a fuel pipe.
[0004] Figure 2 illustrates a graphical representation of fuel built up in the fuel pipe along with the fuel injector opening and closing points.

Detailed description of the invention
[0005] Figure 1 illustrates a method for storing compressed fuel in a fuel pipe 3 that is coupled between a high pressure fuel pump 1 and a fuel injector 2. The method comprises connecting a first end of the fuel pipe 3 to an outlet of the high pressure fuel pump 1, connecting an opposite second end of the fuel pipe 3 to a high pressure connector 4 of the fuel injector 2, storing pressurized fuel within the fuel pipe 3 after the fuel injector 2 has finished delivering pressurized fuel to an engine, and delivering pressurized fuel from the fuel pipe 3 to the fuel injector 2 during a subsequent injection event of the fuel injector 2.
[0006] In addition, a high pressure fuel pump 1 is described. The high pressure fuel pump 1 comprises a pumping chamber and a unidirectional flow control valve in flow communication between the pumping chamber and a fuel pipe 3. The unidirectional flow control valve is adapted to supply pressurized fuel to the fuel pipe 3, the unidirectional flow control valve prevents pressurized fuel from the fuel pipe 3 from returning to the pumping chamber of the high pressure fuel pump 1.
[0007] A schematic of a fuel injection system 10 is depicted in Figure 1. The fuel injection system 10 includes a fuel tank 11. A fuel filter 8 is in flow communication with the fuel tank 11 and receives fuel that is delivered from the fuel tank 11. A high pressure fuel pump 1 is in flow communication with the fuel filter 8 and receives filtered fuel from the fuel filter 8 via a fuel flow path 7. The high pressure fuel pump 1 pressurizes the fuel and supplies it to the fuel injector 2 via the fuel pipe 3. A high pressure connector 4 is coupled to an inlet of the fuel injector 2 and connects the fuel injector 2 to the fuel pipe 3.
[0008] An engine control unit 9 is connected to a rail pressure sensor 6 of the fuel injector 2 via a control flow path and receives a rail pressure signal via the control flow path. In addition, the engine control unit 9 is connected to a solenoid 5 of the fuel injector 2 via a control flow path and facilitates controlling a quantity of fuel that is injected by the fuel injector 2. A fuel return flow path 8 is connected between the fuel injector 2 and the fuel tank 11 and supplies excess fuel from the fuel injector 2 to the fuel tank 11.
[0009] The high pressure fuel pump 1 comprises a pumping chamber. A unidirectional flow control valve in flow communication between the pumping chamber and a fuel pipe 3, the unidirectional flow control valve adapted to supply pressurized fuel to the fuel pipe 3. The unidirectional flow control valve prevents pressurized fuel from the fuel pipe 3 from returning to the pumping chamber of the high pressure fuel pump 1.
[0010] Figure 2 illustrates a graphical representation of fuel built up in the fuel pipe along with the fuel injector 2 opening and closing points. Points A and B represent the opening points of the fuel injector 2. Points C and D represent the closing points of the fuel injector 2.
[0011] Beyond the points C and D which represent the closure of the fuel injector 2, a certain residual pressure is built up in the fuel pipe 3. The residual pressure of fuel that is built up in the fuel pipe 3 can be used to be delivered to the fuel injector 2 without pressurized fuel being delivered from the high pressure fuel pump 1. In an alternate exemplary embodiment, the residual pressure of fuel that is built up in the fuel pipe 3 can be used to be delivered from the fuel pipe 3 to the fuel injector 2 in combination with pressurized fuel delivered from the high pressure fuel pump 1. In yet another alternate exemplary embodiment, the residual pressure of fuel that is built up in the fuel pipe 3 can be used to be delivered from the fuel pipe 3 to the fuel injector 2 during the main injection event of the fuel injector 2.
[0012] A working of the fuel injection system 10 is described as an example. When fuel is supplied from the high pressure fuel pump 1 to the fuel injector 2, the fuel is injected by the fuel injector 2 into the engine. At the end of fuel injection, since all of the fuel in the fuel pipe 3 does not get injected by the fuel injector 2 into the engine, a certain quantity of pressure is maintained in the fuel pipe 3. At the beginning of pilot injection by the fuel injector 2 during the subsequent injection phase, pressurized fuel is delivered from the fuel pipe 3 to the fuel injector 2 without pressurized fuel being delivered from the high pressure fuel pump 1. In an alternate exemplary embodiment, pressurized fuel is delivered from the fuel pipe 3 to the fuel injector 2 in combination with pressurized fuel delivered from the high pressure fuel pump 1. In yet another alternate exemplary embodiment, pressurized fuel is delivered from the fuel pipe 3 to the fuel injector 2 during the main injection event of the fuel injector 2.
[0013] It must be understood that the embodiments explained above are only illustrative and do not limit the scope of the disclosure. Many modifications in the embodiments with regard to leverage and dimensions of various levers are envisaged and form a part of this invention. The scope of the invention is only limited by the claims.