| 摘要 |
A gas injector (10) for a gas fuelled internal combustion engine. The gas injector (10) comprises a valve member (12) adapted to seat against a valve seat (14) in a first or closed position, in which a flow of gas through the injector is prevented, and being movable to a second or open position in which the valve member (12) is lifted from the valve seat (14) to permit a flow of gas through the injector (10). The injector (10) further comprises a solenoid actuator (16) for moving the valve member (12) from the first to the second position responsive to an electrical control signal. In use, by modulating the electrical control signal a precisely controlled quantity of gas can be delivered by the gas injector (10) to the internal combustion engine. Valve member (12) has a conical valve face (18) and a hollow elongate valve stem (20) having a first opening (22) at one end and a second opening in the form of three radial apertures (24) at the other end to allow a flow of gas through the valve member (12) in use. The valve stem (20) is provided with an annular flange (30) at one end, which faces the end face (28) of the solenoid actuator. Annular flange (30) is of magnetic material and forms the armature of the magnetic circuit formed by solenoid actuator (16). Outer casing (50) of the injector is manufactured of magnetic material, and a wall of the outer casing is located immediately adjacent a coil (32) so that, in use, together with a core member (34) and annular flange (30), it forms part of the magnetic circuit of the injector. Careful design of the mechanical structure and magnetic circuit reducesflux leakage and minimises the total air gap to provide a rapid response time for the injector. |
