Patent GB-724023-A (GB)
Title: Improvements in or relating to hydraulic governor systems
Inventor: MURRAY GEORGE HAMILTON
IPC: F02D1/00
Filed: 1953-07-20
Abstract: 724,023. Fluid-pressure servomotor-control systems. NAPIER & SON, Ltd., D. July 20, 1953 [July 28,1952], No. 19057/52. Class 135. A hydraulic speed regulator and servomotor for controlling the fuel supply to the injection pumps of an internal-combustion engine to regulate the speed of the engine, comprises engine-driven gear pumps 1, 34, Fig. 1, supplying pressure liquid to the regulator and the servomotor respectively. The regulator comprises bores 4, 5, 6 in the casing 3 slidably mounting a leak-off piston valve 16 having an arcuate cut-away portion 22, working and stop pistons 9, 10, and a pressure-regulating valve 11 respectively. Pressure liquid from the pump 1 passes through a throttled passage 25 to act on the underside of the stop piston 10, the throttle preventing hunting of the piston, and through a pressure-reducing valve 7. The pressure of the liquid after passing the valve 7, referred to as "balance pressure," acts on the leak-off valve, the lower and upper faces respectively of the pistons 9, 10, and the pressureregulating valve 11. After passing the valve 11 the pressure liquid passes into chambers 13 surrounding the bores 4, 6, and thence through ports 14 to act on the upper face of the piston 9, when the pressure is referred to as " working pressure," and thence through ports 15 and the leak-off valve 16 to a space 50 subjected to sump pressure. A control rod 18 slidably passing through the pistons 9, 10 is connected to thepiston 9 by a spring-biased lost-motion device, to a balance lever 19 engaging the leak-off valve 16 and to a floating lever 29. The lever 29 being connected by a link 331 to the servocontrol valve 33 and by a link 30 to a lever 31 operatively connected to the injection pumps and the servomotor piston 35. A cam 20 about which the lever 19 pivots is manually adjustable to set the position of the leak-off valve and the operating speed of the engine. The valve 7 which is spring-biased towards closure is so tapered that the pressure drop therethrough is approximately proportional to the flow therethrough and hence to engine speed. The piston 9 is urged downwardly by a spring 17 and the piston 10 by a spring 21 abutting the piston and a fixed abutment 101 and over part of its travel by a spring 22 abutting the abutment 101 and a sleeve 23 slidable on the rod 18. A head 27 on the rod 18 on engagement by the piston 10 compresses the lost-motion biasing spring to prevent upward movement of the rod 18 and an adjustable stop 28 limits the downward movement of the piston 10. Thus the supply of excessive amounts of fuel to the engine at any speed is prevented. The servomotor piston 35 is biased towards engine idling position by springs 403, 404, which springs also bias a pressure-relieving valve 40 in the liquid supply system to the servomotor towards closure. An increase in flow from the pump 1 consequent upon an increase in engine speed will cause, after a possible momentary rise in balance pressure, an increase in working pressure relative to the balance pressure to move the working piston 9 and hence the control rod 18 downwards. The lever 19 pivoting about the cam 20 allows increased opening of the leak-off valve and the lever 29 pivoting about the link 30 adjusts the control valve 33 to supply pressure liquid to the underside of piston 35 which moves upwards to rotate the lever 31 and shaft 2 to decrease the fuel supply to the injection pumps and through the link 30 and lever 29 recentres the control valve 33. The shaft 2 is connected to the lever 31 by a dogclutch comprising a sleeve 41, Fig. 7, splined to the shaft and having dogs 411 engageable in recesses 412 in the boss of the lever 31. A sleeve 416 surrounding the shaft 2 and secured to a lever 415 manually operable through a pulley 422 and crank-arm 421 is formed with an end cam face which, on rotation of the lever 415, disengages the clutch and cuts out the servomotor control. Further rotation of the lever 415 may then rotate the shaft 2 to stop the engine. An emergency control to allow the operator to override the regulator comprises a spring-pressed plunger 423 having wings 422 which on rotation of the plunger engage in slots 427. The plunger then passes through a hole in the sleeve 416 into a recess in the shaft 2 to lock the manually-operable lever 415 to the shaft 2 for manual control of the injection pump.