Patent GB-546632-A (GB)
Title: Improvements in or relating to the control of internal combustion engine power units
IPC: F02D13/02
Filed: 1941-01-20
Abstract: 546,632. Fluid-pressure servomotor-control systems. SULZER FRERES SOC. ANON. Jan. 20, 1941, No. 757. Convention date, Jan. 22, 1940. Addition to 456,119. [Class 135] A system for controlling internal-combustion engines as described in the parent Specification is modified by arranging that when the device for limiting the maximum fuel supply comes into operation a follow-up gear associated with the servomotor which regulates the load on the engine is brought into operation and continues in operation until the load is reduced sufficiently to take the limiting device out of operation when the system continues to regulate as described in the parent Specification. In the arrangement shown in Fig. 1 an engine 1 driving a main generator 2 supplying traction motors 4 and an exciter 3 for the field 6 of the main generator is fitted with a centrifugal governor 7. A lever 9 coupled to the sleeve 8 of the governor is connected through a resilient device 11 to a rod 12 regulating the fuel pumps 13 and through a link 10 to a lever 14 coupled to the control valve 15 of a power device 18. The power piston 18 is arranged to operate a rheostat 5 on the field circuit and is coupled to an intermediate part of a lever 17 connected to the lever 14 and fitted at each end with a device adapted to hold one end or other stationary. The device coupled to the junction of the levers 14, 17 comprises a flanged rod 20 adapted to be gripped between a pair of pistons 21, 22 acted on by compressed air or connected to atmosphere by a spring- loaded shuttle-lift valve actuated by a solenoid under the control of a switch 36 in the resilient device 11. The locking device at the free end of the lever 17 comprises a piston 33 working in a cylinder the two ends of which are connected through a valve 26 with a movable seat 27. The seat is coupled by a lever 28 to the fuel pump regulator while the valve is actuated by a piston subject to the changing air pressure. Under normal conditions the junction of the levers 14, 17 is held stationary and the system operates as described in the parent Specification. If the supercharging pressure falls greatly or if the load increases very much the valve 26, 27 closes and the switch 36 opens. This locks the end 34 of the lever 17 and releases the lever 14 to allow this lever to act as a floating lever to restore the control valve to its neutral position. In a modification the piston 33 is provided with a small leakage port or the valve 26 is arranged to remain partly open and the pistons 21, 22 and control valve 23 are replaced by a single spring loaded piston working in a cylinder with a small bleed port. In the form shown in Fig. 3 the lever 14 is pivoted to a stand 43 which during astatic working is retained in a central position by springs 50, 51. When the load limiting device comes into operation a switch 46, 47 is closed to energize a solenoid 44. This causes the serrated end on a lever 45 pivoted to the stand 43 to engage a serrated member 53 secured to the piston 18 and so cause the lever 14 to function as a floating lever for static working. In another form the control valve works in a movable seat connected by a lever to a second lever formed with a serrated quadrant adapted to be engaged by an electromagnetically operated pivoted and serrated member when the load limiting device comes into operation.