GB677324A - Improvements in fuel injection apparatus for internal combustion engines - Google Patents

Abstract

677,324. Fuel injectors. AKTIEBOLAGET ATLAS DIESEL. March 9, 1948 [March 22, 1947], No. 7259/48. Class 7(iii) [Also in Group XXVIII] A fuel injection apparatus comprises a pump having a plunger 5 reciprocable in a cylinder 4 which communicates through a pipe 17 with a fuel injection valve 3, means in the plunger or cylinder providing a small accurately defined vent passage through which the fuel leaks during the initial part of the injection stroke to byepass the plunger, and an actuating cam 6 which has a relatively slow rise 7 for producing a preliminary injection and a relatively steep rise 8 for producing the main injection. The plunger has a peripheral groove 10 communicating with the pump chamber 11 through a small leak passage 12 which forms a restricted byepass from the pump chamber to the supply duct 13 until the latter is closed by the lower edge 16 of the groove. The fuel injection valve which is designed to open at a low pressure and to close against a high pressure, has its nozzle openings 19 controlled by a needle valve 18 having a large piston portion 20 and a small piston portion 21 both of which are subjected to the pressure of the fuel in chambers 32, 27 respectively to raise the needle valve against its loading spring 22. The fuel enters a gallery 24 connected permanently with the chamber 32 and, through a valve 25, provided with a pressure-reduction piston portion, with the chamber 27. A return flow passage 28 communicates with the gallery 24 through a check valve 29 provided with a pressure-reduction piston portion. The valve 29 is held closed by its spring 30 and the pressure in gallery 24 until the pressure therein is released whereupon the needle 18 closes and the valve 29 opens to permit excess fuel in the chamber 27 to escape. In another embodiment the pump and injection valve are formed as a single coaxial unit and the plunger has a slightly reduced end to form the vent passage. In other embodiments a vent plug is provided in the cylinder wall or a 'vee' notch is provided on one edge of a peripheral groove in the cylinder wall or in the end of the plunger. Specification 563,539, [Group XXVIII], is referred to. The Specification as open to inspection under Sect. 91, also discloses construction in which the vent passage is effective during the entire injection stroke. This subject-matter does not appear in the Specification as accepted.