Diesel engine fuel injection valve - delays pressure rise and fall in back pressure chamber to allow valve operation

摘要

The fuel-injection valve has a nozzle body (18) with a seat (28), against which a needle valve (26) is spring-loaded (46). A fuel pressure chamber (32) is pressurised to lift the needle off its seat, while at the valve end away from the seat is a backpressure chamber (42), in which fuel pressure thrusts the needle against the seat. A passage (54,56), connecting the backpressure chamber to the fuel pressure source (10), contains a flow regulator. As pressure from the source rises, it delays pressure rise in the backpressure chamber as compared to that in the pressure chamber, allowing the needle valve to open. As the source pressure falls, it delays pressure reduction in the backpressure chamber as compared to that in pressure chamber, allowing the valve to shut. ADVANTAGE - Rapid injection cut-off, while preventing reverse flow of combustion gases into injector.