| 摘要 |
A conventional fuel injection system meters fuel by varying the time for which the injector is open. This is an empirical rather than fundamental method of metering the fuel. The amount of fuel delivered for a given injector opening time will depend on the pressure difference across the injector orifice and the exact dimensions of the injector orifice. Both these parameters are subject to variation. An injector (1) which comprises a plunger (2), a solenoid coil (3), and a conical return spring (11) which is driving a primary high pressure pump assembly consisting of a primary piston (4) within a primary cylinder (5) together with primary inlet valve (8) and primary outlet valve (7). The plunger (2) is also driving a secondary low pressure pump assembly consisting of a secondary piston (22), secondary cylinder (23), secondary inlet valve (24) and secondary outlet valve (25). The solenoid coil (3) is under the control of an electronic monitor unit (10) which is connected to the solenoid coil (3) via two connecting wires (19). The injector is mounted in and is delivering fuel into an inlet manifold (20). By interrogating various sensors around the engine the electronic monitor unit (10) calculates the amount of fuel it wishes to deliver. From a simple volumetric calculation the electronic monitor unit (10) calculates how far the piston (4) must be moved to deliver this amount of fuel. |
