US2712300A - Hydraulic governors for internal combustion prime movers - Google Patents

Description

J y 1955 R. J. lFlELD 2,712,300

HYDRAULIC GOVERNORS FOR INTERNAL COMBUSTION PRIME MOVERS Filed July 11, 1950 United States Patent HYDRAULIC GOVERNORS FOR INTERNAL COMBUSTION PRIME MOVERS Richard Joseph Ifield, Dural, New South Wales, Australia, assignor to Joseph Lucas Limited, Birmingham, England Application July 11, 1950, Serial No. 173,093

Claims priority, application Great Britain July 26, 1949 3 Claims. (Cl. 121-38) tle valve in the fuel supply system, or otherwise vary the rate of fuel supply to the prime mover in response to variations of engine speed.

In such governors it is already known to utilise fluid supplied by a pump (which may be the fuel pump, or alternatively a pump whose sole duty is to supply the governor), and cause the fluid to pass through a manually operable throttle (hereinafter referred to as the control throttle) for setting up a pressure difference in the fluid at opposite sides of the throttle, this pressure difference being caused to act on opposite sides of a fluid-pressure responsive member adapted to actuate a valve associated with the servo mechanism.

The object of the present invention is to improve the action of governors of the type above specified.

The invention comprises a governor of the said type, having combined therewith a pair of throttles arranged in series, (at least one of the throttles being automatically adjustable) and adapted to control the pressure difference acting on opposite sides of a spring loaded fluid-pressure responsive member associated with the valve of the servo mechanism.

The accompanying diagram illustrates an embodiment of the invention.

In carrying the invention into effect, as shown in the diagram, there is employed any convenient and known form of servo-mechanism for varying the output of the main fuel pumps, or for varying a throttle or other control means located in the system between this pump and the combustion chamber of the prime mover from which the pump derives its motion. In the example illustrated, the said mechanism comprises a piston a slidable in a cylinder b and loaded by a spring 0. The ends of the cylinder are in communication with each other through a restricted orifice d. Liquid fuel from the pump 2 is bypassed to one end of this cylinder, and at the other end is provided a vent under the control of a valve f.

In this example, the said servo-mechanism serves to vary the output of the pump, which is of the swash plate type, the piston a being connected to the angularly adjustable swash plate g of the pump. But the servo-mechanism may, as already stated, be used for controlling in any other manner the rate of supply of liquid fuel from a pump to a burner h.

The governor comprises a flexible diaphragm i containedin a chamber j and loaded by a spring k, and movement of the diaphragm is employed to actuate a lever m carrying the above mentioned vent valve 1. Fluid is supplied at different pressures to opposite sides of the diaphragm from the opposite sides of a manually operable control throttle n adapted to set up the desired pressure difference in the fluid. In the example shown the throttle is movable by a lever 0 through a rack and pinion mechanism p. The fluid which acts on the diaphragm i may be supplied by the main pump e or (and as shown) by a separate pump q whose sole duty (as above mentioned) is to actuate the governor.

In one mannerof applying the present invention to a governor as above described, there is provided anautomatic throttle r, between the control throttle n and the low-pressure side of the diaphragm i associated with the vent valve 1 of the servo-mechanism. The automatic throttle comprises an axially movable plug of tapered or other appropriate form located in an orifice s through which fluid can pass from the control throttle toone side of the diaphragm i. The throttle r is carried by a diaphragm t loaded by a spring a in a chamber v which is in communication with the low-pressure side of the diaphragm i.

The outlet s is arranged to be in communication with the upper side of the diaphragm t by way of a restricted orifice. In the example shown, the throttle r is formed with an axial bore, and the restriction is provided-in this bore as indicated by y. The restriction may, however, be provided in any conveniently arranged passage extending from the low-pressure region beyond the'throttle r and the said side of the diaphragm. 1

The arrangement is such that the operating fluidpasses from the inlet side of the control throttle n to the highpressure side of the diaphragm i, and the fluid which has passed through the control throttle n enters the region at the low pressure side of the said diaphragm i, through the automatic throttle r, and from that region the fluid flows to a sump w or the inlet side of the pump q.

The pressure difference operative upon the controlling diaphragm i is determined by the sum of the pressure drops due to the control throttle n and the automatic throttle r since these are in series. The higher pressure at the entrance side of the control throttle it acts upon the upper side of the diaphragm i while the lower side of said diaphragm is subject to the pressure at the inlet side of the pump q. If the control throttle n is opened for example, the pressure drop across it will be reduced, thereby reducing the total pressure drop due to the two throttles and actuating the diaphragm i in a direction to effect a closing movement of the valve f and thus tend to increase the pump output. The resulting increase in speed of the prime mover increases the delivery of the pump q so that the pressure drop across the throttle n is increased, but this can take place only after an interval of time required for the acceleration of the prime mover. If the automatic throttle r were not present, the initial reduction in pressure drop due to opening the throttle n. would, by actuation of the diaphragm i during such time interval, be liable to cause too great an acceleration of the prime mover. The automatic throttle r is not immediately adjusted following the opening of throttle it, since movement of its diaphragm t is opposed by the liquid above it which can escape only at a controlled rate through the restriction y. The pressure drop due to the throttle r is accordingly maintained for a period and consequently the full effect of the reduction in pressure drop across the control throttle n is not immediately effective upon the diaphragm i and thereby excessive acceleration of the prime mover is thereby obviated or minimised. The increased rate of flow due to the opening of the control throttle n causes an upward movement of the diaphragm t at a controlled rate and this diaphragm will come to rest when the pressure difference across the throttle r balances the force exerted by the loading spring. It will be seen that the delay in action of the automatic throttle r maintains in part the pressure drop effective upon the controlling diaphragm i and thus the time interval, which would otherwise elapse (in the absence of th .automaticthrottle 1') before suchpressure difference is increased due to acceleration of the prime mover and acts on the controlling diaphragm i to reduce thejratevof fuel supply, is shortened. In this way the governor can maintain the speed of the prime mover more closelywithin thedesired limits. It will be appreciated that a similar result is obtained when the control throttle n is moved towards closed position to decrease the pump output. Instead, of, havingthe form of diaphragms as shown the members i and 2 may have the form of pistons. By theuseof an automatic throttle r as above described, normal action of a governor of the type to which the invention relates can be advantageously improved. The, invention is not, however, restricted to the example described, as details of construction or arrangement may, be varied to suit different requirements, thus, the relative disposition of the two throttles may be reversed.

Having thus described my invention what 1 claim as new and desire to secure by Letters Patent is:

1,. A hydraulic governor for controlling afluid operated servo mechanism comprising, in combination, a fluid-pressure responsive member, a valve for controlling the, servo mechanism operable by said member, a pairof adjustable throttles in series connection, a con nection from the entrance, side of said series connected throttles to one side of said pressure responsive member, a connection fromrthe discharge side of said series connected throttles to the other side of said pressure responsive member, pressure responsive means for actuating one of said throttles in accordance with a change in fluid pressure-due to adjustment of the other throttle, and means for, delaying the adjustment of the first throttle by said pressure responsive means.

7 2. A hydraulic governor for controlling a fluid operated servo mechanism comprising, in combination, a chamber containing a fluid pressure responsive member which divides the chamber into two compartments, a valve for controlling the servo mechanism operable by said member, a throttle, a connection between the entrance side of said throttle andone of said compartments, a second throttle in series with the first throttle, a connection between the discharge side of said second throttle and the other of said compartments, a second chamber containing one of said throttles, a fluid-pressure responsive member in said second chamber for actuating said throttle in accordance with changes of fluid pressure due to adjustmentof the other throttle, and means for retarding the operation of said fluid-pressure actuated throttle.

3. A governor according to claim 2-, in which the second chamber is divided into two compartments by its fluid-pressure responsive member, and a restricted o'rifice means aflfords communication between said compartments whereby operation of said member due to a change of pressure in one of the compartments is delayed.

References Cited in the file of this patent UNITED STATES PATENTS 941,426 London Nov. 3 0, 190 9, 1,814,827 Caugh ey July 1'4, 1931 2,369,397 Ko'stenick Feb. 13, 1 945 2,372,393 Ray Mar. 27, 1945 2,424,035 'lfiel'd July l5, 1947 FOREIGN PATENTS 589,722 Great Britain June 27, 1947

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