Preventing damage to a compression-ignition i.c. engine by providing a continuously hot site to burn off incorrectly injected fuel

摘要

In the event of a fault in an electrically controlled injection valve 15 or the electric control unit 10 such that high pressure fuel is injected continuously, a continuously hot site in the combustion chamber maintains a burning flame beyond the expansion stroke until the end of the induction stroke, as long as atmospheric oxygen together with fuel are still available, thus preventing damage to the engine. The hot site may be provided by a glow body 30 mounted in insulation 34 in the wall of the combustion chamber in the region of the injection jets 36 and heated by the combustion. Alternatively, the hot site may be formed by a glow plug 31, by the insulated base 32 of the piston 25 or by a spark plug 33 which is fired at BDC. If the control device 10 detects malfunction eg by engine speed fluctuations, the injectors 15 or the high pressure injection pump 18 may be closed down. Alternatively the EGR return valve 6 may be fully opened while the air throttle 8 is held closed thus starving the engine of oxygen. The EGR return path may be kept short to assist the continuing combustion of incorrectly injected fuel.