Patent GB-529780-A (GB)
Title: Improvements in or relating to the governing gear of engines and other machines
IPC: G05D13/00
Filed: 1939-05-26
Abstract: 529,780. Speed governors. TIPPEN, F. J. May 26, 1939, No. 15626. [Class 135] A speed governing mechanism having a horizontal or rising characteristic has the centrifugal governor connected to one arm of a rocking lever and the regulating means of the engine or machine connected to the other arm, while speed correcting mechanism including a fluid pressure motor is adapted to move the fulcrum of said lever under the control of a pilot valve connected to the first-mentioned arm of said lever. As shown in Fig. 1, a speed governor of the type comprising balls 6 arranged in grooves 7 between a plate 8 fixed on an enginedriven shaft 1 and a slidable cup 2 keyed to the shaft is connected by a rod 15 to one end of a lever 18 connected at its other end to a rod 19 which operates the fuel pump control in the case of a compression-ignition engine, or the carburettor throttle in the case of a petrol engine. The fulcrum 20 of the lever 18 is provided on the piston rod 21 of a piston 12. The piston 12 forms part of the overriding adjustment and is movable in a cylinder 11 under the control of a piston valve 13 formed on the rod 15. The valve 13 moves in a valve chest 14 provided with inlet and exhaust ports 24, 25 for pressure fluid which may be derived from the pressure lubricating system of the engine or from a separate engine driven pump. The bands 31, 32 of the valve 13 may control the cylinder ports 26, 27 directly, but to ensure accurate location of the ports and to adjust the predetermined speed independently of the governor loading spring 9, a separate axially adjustable sleeve 28 with circumferential grooves and ports or sets of ports is provided. Assuming the load on the engine increases, the cup 2 moves the lever 18 clockwise about the fulcrum 20 so that the rod 19 is moved by an amount proportional to the governor movement to increase the fuel supply. At the same time the valve 13 is moved to allow fluid to pass to one side of the piston 12 and to exhaust from the other, the subsequent piston movement slowly moving the rod 19 in the same direction to increase the fuel supply still further. The overriding adjustment device continues to act until the valve 13 resumes its central position in which the speed is restored to normal. The arrangement shown in Figs. 2, 3 operates in a similar manner but in this case the governor cup 2 is connected to an arm 48 which operates the speed controlling means, e.g. the rod 19, by a fork member 43 which with the arm 48 is fixed on a shaft 42 journalled in eccentrics 37, 38 themselves journalled in a case 40. The limbs 44 of the fork 43 are joined by a rod 45 which passes through slots 50, 51 in the eccentric 38 and valve chest respectively into a slot 54 in an enlargement 53 of the piston valve which is otherwise similar to the valve shown in Fig. 1. The servo-piston 12 is formed with cuplike ends forming chambers 69 into which fixed plugs 59 extend. Liquid is only slowly admitted to the chambers 69 from the inlet passages 67, 68 due to the restricted clearance between the piston and the plugs 59. The piston 12 is operatively connected to the eccentrics 37, 38 which are themselves rigidly connected, by a pin 56 on a downwardly-extending crank arm 55 on the eccentric 38. The pin 56 engages a slot 58 in the piston. The shaft 42, and the pins 45, 56 are in vertical alignment with the axis of the eccentrics when the speed and load are normal, but they conclude in alignment in a plane inclined to the original vertical plane with variation of load. The axial adjustment of the sleeve 28 in this form is effected bv a head 70 which has an eccentric pin engaging the sleeve, and is clamped by a screw 73. Both forms may be modified to operate with a rising characteristic, for instance by cranking the outer end of the pin 45 downwardly to give it greater leverage than that afforded by the forks 44. A spring 75, Fig. 1, moves the speed-controlling means automatically to the " stop " position if the lubrication system fails. The governor shaft may operate a motive fluid-supply pump through skew gears and the rod 19 may operate the speed controlling means through servomechanism such as that described in Specification 511,344.