GB1478150A - Fuel supply control system for an internal combustion engine - Google Patents

Abstract

1478150 Regulating fuel supply CUMMINS ENGINE CO Inc 14 Aug 1974 [22 Aug 1973] 35873/74 Heading F1B A fuel pressure regulating system for an I.C. engine with fuel injection comprises a throttle valve for controlling the fuel pressure at intermediate engine speeds, a governor for controlling the fuel pressure at maximum and minimum throttle openings for determining the maximum and tickover engine speeds and a regulator for varying the fuel pressure as a function of engine speed when under load. Fuel drawn from a tank 10 by a pump 22 passes via a line 29 into an engine-driven governor 16 which comprises a plunger 34 held in contact with governor weights 63, 64 by a spring 61. The plunger 34 controls flow from an inlet port 36 to outlet ports 38, 39. Throttle valve 44 receives fuel from port 39 and delivers it via port 55 to fuel injectors 11, the injection pressure being controlled by a throttle lever 58 via a cam 57 and a spring 54. When the throttle valve is closed and the engine speed is at tickover, fuel then passes from outlet port 38 via line 41 to the injectors 11, the tickover speed being maintained constant by throttling of the port 38. As the throttle valve is opened, fuel passes through port 55 to the injectors, port 38 is obstructed as the engine speeds up and fuel flows to the injectors only via port 39. If the engine reaches a preselected maximum speed, throttling at port 39 prevents that speed from being exceeded. A pressure regulator 111 permits a portion of the fuel flowing to governor 16 to return to the fuel tank via a spring loaded valve 119, the pressure in line 29 therefore being governed by the force of a spring 121 which is in turn controlled by the pressure in line 99 which communicates with a passage 91 within plunger 34, the passage being closed by a sealing member 76 held in contact with plunger 34 by spring 61. Fuel which enters passage 91 via ports 92 depresses sealing member 76 when the force due to the fluid pressure exceeds that of spring 61, the fuel returning via line 85 to tank 10. Since the force of spring 61 is a function of engine speed, the pressure in passage 91 and line 99, and consequently the force of spring 121 is dependent upon engine speed. When the throttle valve is fully open, and the engine is under load the engine speed increases, the action of regulator 111 therefore causing the pressure in line 29, and subsequently the injection pressure to increase with increasing engine speed. The force of spring 61 may also be varied by a lever 70 which with the throttle valve fully open, permits the governor 16 to maintain the engine at a constant preselected speed independent of load. In another embodiment, Fig. 4 (not shown) the regulator 111 is designed so that when the pressure in line 99 exceeds a given value, the spring force falls thereby permitting a fall in the pressure in line 29 and a consequent drop in the injection pressure.