| 摘要 |
<p>An electromagnetic unit fuel injector for use in a multi-cylinder diesel engine has an externally actuated pump (10, 11) for intensifying the pressure of fuel delivered to a pressure-actuated injection valve (511 which controls flow discharge out through a spray outlet (53) and is normally biased to a closed position by a spring (65) Pressurized fuel from the pump is also supplied via a throttling orifice (43) to a modulated pressure servo control chamber (56) having a servo piston means (62) operatively associated with the injection valve. A drain passage (66) extends from the servo control chamber, with flow therethrough controlled by a solenoid-actuated control valve in the form of a poppet valve (68) which is normally biased to a closed position by a valve return spring (84) of predetermined force, whereby the control valve is also operative as a pressure relief valve.</p><p>A secondary pressure relief valve means (133) is preferably additionally incorporated into the unit injector so that all of the unit injectors for the engine will operate at a uniform maximum peak pressure.</p> |
