US2674191A

US2674191A - Hydraulic speed governor for prime movers

Info

Publication number: US2674191A
Application number: US180656A
Authority: US
Inventors: Ifield Richard Joseph
Original assignee: Joseph Lucas Ltd
Current assignee: ZF International UK Ltd
Priority date: 1949-08-22
Filing date: 1950-08-21
Publication date: 1954-04-06
Anticipated expiration: 1971-04-06

Description

April 6, 1954 i R. J. IFIELD HYDRAULIC SPEED GOVERNOR FOR PRIME MOVERS Filed Aug. 21, 1950 Patented Apr. 6, 1954 PATENT omcg HYiiRAUL'Io s'rliiioggy zo mwon FoR PmME Richa'r d vJoseph Ifield, Dural, newsman wales, Australia, assignor to Joseph Lucas Limited, Birmingham, England Ap'plicationAligu St 21, 1950, Serial N0.180,656

Claims priority,"application Great Britain August 22, 1949 Claims. (CL' 103-11) This invention relates to hydraulic governors for prime movers, such as jet propulsion engines, gas turbines and the like, the governors being ofthe kind adapted to control a liquid-operated servo mechanism for varyingthe output-of a fuel supply pump or otherwise regulating the supply of fuelto the prim mover in responseto variatijons of speed. t t t 'The inventionhas for its object toenable the speed at which" the governor comes: into action to be kept substantially constant over a wide range of variation of the'rate at which the fuel is supplied to the prime'rnover. V I H I The invention comprises the combination of a valve for controlling th servo'r'nechanism, liquid-operable means for 1 actuating the valve, the said meansbeing in communication witha by-passpassage extending from the'fuel supply system, a variable throttle, adapted to control the flow of liquid through the by pa'ss'passage, a dash pot responsive tothe pressure of the liquid in the said passagefor actuatingthe'throttle, and means adapted'to'set up in'the said passage a counterpressure related to thespeed of the prime mover.

The invention also comprises the combination withthe' means specified in the preceding paragraph, of an isolating valve for temporarily closing the'bypalss passage while the prime mover is being started.

The accompanying drawing illustrates diagrammatically one embodiment of the invention. Y j Referring to the drawing, the liquid fuel supply p ump there shown is of known form and comprisesa rotor a having'thereina plurality of bores each containing a spring-loaded plunger b,'the rotor being contained in a housing 0. Actuation of the pl'ungers is effected by a swash plate d. For adjusting the obliquity of theswash plate there is provided a liquid operated servo mechanism, which consists of a piston e connected to the swash plate by 'arod f. The piston is slidable in a cylindrical chamber 9 andis loaded at one side by a spring h. The two ends of the cylinder are interconnectedby a'passage 2' containing a restricted orifice'y, and the end of the chamber gremote from thespring is in communication with the discharge passage is of the pump. The end of the chamber 9 containmg the spring h is' in communication with a passagem leading to the "seating no: avalve 'o,' which' is carried by a lever 1) and loaded by'a 'springi q. Ilie-parts n o, 'p, q, are "contained-' in a 'chambr' r"which is in communication with the inlet passage 2, and "which is separatedfromfan'adiacent chamb'r s by a flexible diaphragm't (oranjequivalent piston), the diaphragm beihgfioaded'byfa tensi'on spring '11,. -l/ I'0w'ament can be transmitted from' the" diaphragm to the levenp by-a {stem w. The arrangement is that'when 'thevalve' o is closed, the spring fh rnoi esthe' pistonkin the direction for increasingth'e pump output. When the valve 0 is open, the preponderating liquid pressure acting on the lft hand side "of the 'piston moves the latter'inthediiection for 'reducing the pump output. L

Thecha'r'nber s is'n communication with the pump housing c' way fofa passageaz, andthe rotor 'c are formedsubstantially-radial passages yenabling the'i'ot'o'r to'ser've also as a centrifugal purn'p, so that liquid drawn from the inlet passage2 of thefuel pump can'bedischargedinto the housing 0 at "a pressure determined by the rate of rotation'oftherotor, the latter being driven by "any convenient part of the prime mover to be suppliedwith' l'iquid fuel.

In association with "the arrangement above described there is provided a" cylindrical chamber 3 containing aslidable throttle!"co-operating Withanorifice'E, and the portion *of the chamber S'beneaththe said'prifice-is connected by a pipe 6 to th above'mentioned'passage 21:. 'Also at a positionabove thebrifice 5 "the 'ch'amberfl is connected by pipes "I, 8,to the servo cy'linderg at the end which is in communicatiom'withthe pump delivery passage k. The-pipesl, Bja'r'e'interconnected through "an "isolating valve to be hereinafter described.

The "throttle 4 is'arranged' at" one end of "'a rod 9 extending 'from'adash-potfpiston l0 'slidable inthe chamber 3 ,"and having th'ereina restricted orifice l I. The-pistoni-sattached'to' a tension spring 112 which is' ad astsuepyascrew I 3.

The pipes 8, "If-and 5, thefpas'sage :v, the chamber c, andthe passages yin the pump rotora constitute aib'y p'ass passage interconnecting the pump delivery passage '10 andthe pump inlet passage 2. The flow through 'thefby-pass passageis controlled'inpartby the throttle l4 and in'p'artb'y the counter-pressure exerted by the centrifugal pump. It follows that the pressure in the chamber s is the sum of two variable pressures, one of them being related to the pressure in the pump delivery passage To and determined by the throttle 5, and the other being determined by the rate of rotation of the pump rotor (1.

Assuming that the system is in a steady state,

and working at the desired rate, the valve will be open, and the passage through the orifice will be restricted by the throttle 4 to an extent depending on the liquid pressures then acting on the diaphragm t and piston 50. A change in this pressure due to either a change of pressure in the fuel delivery system, or in the counterpressure of the centrifugal pump, will result in a corresponding change in the condition of the valve 0. Thus, with a fall in the speed of the pump rotor, the pressure in the chamber s will fall correspondingly. The effect of this is to cause the valve 0 to move to, or towards, its closed position and so cause the servo mechanism to vary the position of the swash plate and thereby increase the pump output. Meanwhile the said fall of pressure will also manifest itself at the throttle, and the spring I 2 will gradually move the throttle to a more open position at a rate dependent on the dash-pot action associated with the piston I ll. Eventually a new state of adjustment will be attained, and the liquid pressure in the chamber s will be restored to its previous amount, thus restoring the initial condition of the system. An increase of pressure above the previous amount in the fuel supply system will cause the throttle to move in the direction for reducing the flow through the part 5, causing the pump output to be reduced until the previous condition is restored.

To obviate loss of fuel from the supply system through the by-pass passage, while the prime mover is being started, there is provided the isolating valve above mentioned. In one convenient form this comprises a closure member l4 co-operating with a seating l5 to which is connected the pipe 8. The closure member is carried by a diaphragm I 6 (or piston) in a hollow body part I1 which is divided by the diaphragm into two compartments. The lower compartment is connected to the pipe 1, and the upper compartment is connected by a pipe i 8 to the pump inlet. Also the upper compartment contains a compression spring !9 which holds the closure member on its seating until the pressure in the pum delivery assage 70 reaches a predetermined amount. When the system is operating normally the closure member I4 is held off its seating by the fluid pressure acting on the diaphragm.

By this invention the desired action of the governor can be obtained in a very simple and reliable manner.

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

1. A hydraulic speed governor for a liquid operated servo mechanism for controlling the rate of supply of liquid fuel to a prime mover from a pump driven thereby comprising, in combination, liquid pressure responsive means arranged to actuate a valve for controlling said servo mechanism, a by-pass passage afiording communication between the inlet and the discharge or the pump and having a connection with said pressure responsive means, a variable throttle for controlling liquid flow in said by-pass passage, means for creating in said by-pass passage a liquid counter-pressure related to and varying with the speed of the prime mover and opposed to the pump discharge pressure whereby the difference in said opposed liquid pressures actuates the pressure-responsive means, andmeans including a dash-pot responsive to the liquid pressure in the by-pass for actuating the variable throttle in a direction to restrict flow of liquid in the by-pass when the pressure therein rises and vice versa, said throttle actuation being effected at a controlled rate determined by the dash-pot.

2. A hydraulic speed governor according to claim 1, comprising an isolating valve in the bypass passage for temporarily interrupting liquid flow therethrough while the prime mover is being started, and means operated by the pressure of liquid delivered by the pump for opening said isolating valve.

3. A hydraulic speed governor for a liquid operated servo mechanism for controlling the rate of supply of liquid fuel to a prime mover from a pump driven thereby comprising, in combination, liquid pressure responsive means arranged to actuate a valve for controlling said servo mechanism, a by-pass passage aflording communication between the inlet and outlet of the pump and having a connection with said pressure responsive means, means forming a cylindrical chamber constituting part of said by-pass passage and having therein an orifice, a throttle valve movable in said orifice for controlling liquid flow in the by-pass passage, a dash-pot piston connected with the throttle valve and movable in the chamber under the pressure of liquid therein to actuate the throttle valve in a closing direction when said liquid pressure rises and vice versa, a spring acting on the piston, restricted passage means afiording communication between parts of the chamber at opposite sides of said piston, and means for creating in the by-pass passage a liquid counter-pressure related to and varying with the speed of the prime mover and opposed to the pump discharge pressure whereby the difference in the opposed liquid pressures in the by-pass is employed to actuate the pressure responsive means.

4. A hydraulic speed governor according to claim 3, in which the means for creating the liquid counter-pressure comprise a centrifugal P p.

5. A hydraulic speed governor for a liquid operated servo mechanism for controlling the rate of supply of liquid fuel to a prime mover from a pump driven thereby comprising, in combination, liquid pressure responsive means arranged to actuate a valve for controlling said servo mechanism, a by-pass passage afiording communication between the inlet and the discharge of the pump and having a connection with said pressure responsive means, a variable throttle for controlling liquid flow in said by-pass passage, means for creating in said by-pass passage a liquid counter-pressure related to and varying with the speed of the prime mover and opposed to the pump discharge pressure whereby the difierence in said opposed liquid pressures actuates the pressure responsive means, means including a dash-pot responsive to the liquid pressure in the by-pass for actuating the variable throttle in a direction to restrict flow of liquid in the by-pass when the pressure therein rises and vice versa, said throttle actuation being effected at a controlled rate determined by the dash-pot, and an isolating valve in the by-pass passage for temporarily interrupting liquid flow therethrough and comprising a chamber, a liquid pressure responsive member dividing the chamber into two compartments one of which forms a part of the by-pass passage and is provided with a seating, a closure member carried 5 by the liquid pressure responsive member and arranged to co-operate with said seating, and a spring acting on the liquid pressure responsive member, the arrangement being such that pressure of the liquid delivered by the pump opens 10 the closure member or the isolating valve.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Ifield et a1 July 2, 1946 Ifield July 15, 1947 Watson et a1 Oct. 14, 1947 Ifield Apr. 27, 1948 Ballantyne et a1. Aug. 22, 1950 Mordell et a1. Jan. 16, 1951