US2466438A - Governor - Google Patents

Description

Patented Apr. 5, 1949 UNITED STATES PATENT OFFICE.

GOVERNOR Albert Kalin, Cleveland, Ohio Application May 1, 1943, Serial No. 485,313

Claims.

This invention relates to an improvement in governors of the type adapted to control the speed of prime movers (e. g. Diesel engines) when subject to varying load, and more particularly to an improvement in such governors which provides for more accurate speed control by the governor upon starting the prime mover from rest and the prevention of over-shooting in speed and excessive hunting during acceleration from standstill to an adjusted speed. This application is a continuation in part of my copending application Serial No. 385,228, filed March 26, 1941 (now Patent No. 2,324,514).

Under certain conditions serious damage can be done to prime movers by attempting repeatedly to increase power input thereto at too high a rate. Diesel engines if operated at nearly maxithe governor with consequent prolonged hunting. The present invention is concerned mainly with an arrangement for preventing operation of a speed regulating servo-motor of the governor in power-input-increasing direction-"from a condition of standstill at rates which; might cause damage to the engine or cause pronounced hunting at starting as a result of the engine greatly overshooting the adjusted speed as the governor assumes control, while nevertheless enabling acceleration of such engine from zero fuel to idling fuel at a rate insuring positive governing and deceleration at such a rate as to prevent the engine from stalling when the speed level setting is suddenly reduced to a low level. The foregoing indicates one object hereof, and the term cushioned start as hereinafter used refers to the function of the present governor mechanism in so controlling the rate of acceleration from standstill that excessive hunting is greatly reduced or prevented.

Other objects are to provide means, effective only upon starting of a prime mover, for 1) preventing radical overshooting of speed and (2) delaying the speed adjusting operation of the governor in respect to the prime mover.

Another object is to provide a hydraulic damping means, effective only upon starting of a governed prime mover, for controlling the speed adjusting operation of the governor so as to prevent the prime mover from greatly overshooting the set speed.

Still another object is to provide in a hydraulic relay governor for a prime mover an auxiliary servo-motor which, during starting of the prime mover, temporarily reduces the effective force of a speeder spring such as usually interposed between the manual or power driven speed adjusting means and a hydraulic pilot valve for controlling the speed regulating operation of a main servo-motor.

A further object is to provide in a governor for a prime mover a hydraulically acting means operable automatically at commencement of gov ernor operation 'io delay the full application of the'eifective force of manual speed setting means on the automatic speed governing means.

A still further object is to combine the cushioned start operation with that of a hydraulically operable speeder-spring-adjusting power head.

The drawing shows one illustrative form of governor mechanism on which the invention can be used which is essentially the one shown in my Patent No. 2,219,229, issued October 22, 1940.

Fig, 1 is a central vertical sectional assembly view of a governor incorporating the present invention; Fig. 2 is a sectional view taken generally at 2-2 of Fig. 1; and Fig 3. is a fragmentary detail sectional view of a modification which may be used to render unnecessary an auxiliary cushioned start servo-motor such as shown in Fig. 1.

The principal parts and assemblies of the lilustrative governor mechanism are indicated mainly by letters and the special subject matter hereof usually by numerals.

In Fig. 1, a base casting W defines a lower portion of a sump S which lower portion is in open communication through a duct (not shown) with an upper portion of the sump S in a power case X. A gear pump partly shown at X coupled with a main drive shaft W is arranged to cooperate with a well known reversible check valve system (only partly shown) and appropriate fluid ducts to enable the pump to draw fluid from the lower part of the sump S and deliver it to a suitable accumulator, such as shown in said copending application, which accumulator functions to maintain a more constant hydraulic pressure than could be maintained by the pump alone in view of changes in speed that would be imparted to the pump as the load is changed on the governed engine.

Fluid from the accumulator is supplied as through passages X" to a governor port E and continuously therebeyond through a duct E to an upper face F of a double acting hydraulic speed regulating servo-motor power piston G. The port E is controlled by a lower land portion of a pilot valve plunger H rotatable and slidable .tatably mounted axially in a pilot valve sleeve H and which plunger, if moved downwardly from the normal position in which it is shown, opens the port E to a duct I and thereby to the lower and effectively larger face J of the power piston G, causing upward movement of said power piston. Upward movement of the pilot valve plunger H from its normal position causes an upper land portion thereof to vent the duct I at a port K, dumping pressure fluid from below the power piston G into the upper portion of the sump S and causing the piston G to descend by reason of the constant pressure maintained at the piston face F through the duct E.

The pilot plunger His moved axially in opposite directions as a result of the difference between centrifugal force on a set of fly balls L suitably rotated by the prime mover and an opposing force exerted by an adjustable speeder spring M, so

that an increase in speed on part of the prime mover raises the pilot valve plunger H and a decrease in speed lowers said plunger. Regulation of speed by the servo-motor power piston G incident to change in load is initiated by such movement of the pilot valve plunger H. An automatic adjusting connection between the speeder spring M and the pilot valve plunger H which serves to provide a cushioned start of the prime mover will be described subsequently.

Power input to the governed prime mover is increased by raising the power piston G and decreased by lowering said piston as indicated on the drawing. Thus, in governing, for example, a Diesel engine, an increase in load causes decreased centrifugal force on the the pilot valve plunger, thus initiating an increase in the rate of supply of fuel to the engine; and a decrease in load causes raising of the pilot valve plunger and consequent decrease in the rate of supply of fuel.

A hydraulic relay governor arrangement such as thus far described requires stabilization in order to prevent sustained vacillation in speed or hunting consequent upon load change and subsequent speed-correcting operation of the governor. The stabilizing mechanism includes a hydraulic compensation system supplied with fluid from the sump and actuating and receiving compensation pistons function of regulating movement of the servomotor piston G to damp or check each movement of said piston and prevent temporary overregulation of the prime mover thereby.

The actuating compensation piston N works in a trunk portion of the power piston G and displaces hydraulic fluid in a duct leading to a receiving compensating piston P, slidably and roin valve sleeve H', whenever the power piston G starts to perform a speed regulating operation in either direction. The motion of the receiving compensation piston P is always opposite the regulation-initiating movement of the pilot valve plunger H, and places temporary primary yieldin: compensating restraint on such movement of the plunger H through the intermediary of a coil spring Q connecting the compensating piston P and the valve plunger H. The primary compeneating force is removed, after regulation is effected, by relieving the positive or negative pressure in the duct 0 through an adjustable secondary compensation leak-off needle valve R communicating the duct 0 with the sump S through the upper part of the actuating compensating pisfly balls and lowering of the lower portion of the pilot of said system operating as a Q being placed in As fully explained in said copending application, the fly balls L cause continuous rotation of the pilot valve plunger H in its coacting fixed valve sleeve H through contact of the ball arm fingers with a disc portion h of the pilot valve plunger; and the spring Q is so connected with the plunger H and receiving compensating piston P that the piston is likewise rotated in the valve sleeve H. This eliminates the possibility of binding of either the valve plunger 'H or the piston P due to foreign matter in the hydraulic fluid and assures that the pilot valve is free from static friction and therefore free to respond to very slight changes in speed. The spring Q also allows relative axial movement between the parts connected thereby so that the valve is always free to respond promptly to any change in centrifugal force acting on the fly balls L.

In operation, when the engine load is increased the resultant decrease in speed causes relative inward movement of the fly balls; lowering of the pilot valve plunger H; opening of the port E; admission of hydraulic fluid through duct I to the lower side of the power piston G; and

increase of fuel to the engine. The upward movement of the piston G pumps fluid through duct 0; raising the receiving compensating piston P, compressing the spring Q and exerting a slight upward force on the pilot valve plunger H sufficient to offset the temporary overbalance of speeder spring force relative to the centrifugal force on the fly balls, thus closing the port E. The port E is ordinarily closed quickly enough to prevent overtravel of the power piston G in the speed correcting direction; and, as the engine returns to normal speed, the compression force of the spring Q is dissipated by reason of leakage of fluid from the duct 0 into the sump 8 through the secondary compensation leak-off aperture of the needle valve R. I

The mechanism operates the same as described above for a decrease in load except that all the movements are reversed, the compensating spring tension by suction action of the compensation fluid system, and hydraulic fluid being finally drawn from the sump into the duct 0 through the aperture of the needle valve R to relieve said tension.

For adjusting the speed of the engine to a predetermined value at which it continues to operate steadily after starting and after any load change with. an ensuing brief period of speed stabilization effected by the governor, a suitable speed setting mechanism such as shown at the upper part of Fig. 1 may be used, said mechanism being essentially that shown in my said Patent No. 2,324,514. As illustrated, a speeder lever which cooperates with the pilot valve plunger H through the intermediary of the speeder spring M has intermediately of its ends a pivotal connection (trunnion pin connection, not shown) with a speeder plug V against which the upper end of the speeder spring M is operatively maintained or to which the spring may be secured as at spring-coil-receiving thread-like grooves on the lower end of a screw Y threaded into the speeder plug V and locked in position as by "a lock nut Y. The lower end of the speeder spring M is operatively associated with the pilot valve plunger H in a manner to be described later.

One end of the speeder lever U (right as shown) has a pivotal support Z which, for the present purposes, may be considered fixed so thatdow'nward movement of the left or opposite end of friction or other driving the lever U; compressesv the speeder spring M vlded between its perimeter and the walls ofthe and sets the governor for higher thanassumed bore l1. I

- speed and upward movement of said left end The plug 28'norma11y blocks two lateral ports 2e a'nd30 th ernor-for lower than assumed spee I ,5" l2. The port 29 communicates freely with the the valve of the power head."

As shown in Fig. '1, the left n lever U is pivoted to an uprigh power head piston dly ceases.

moves up and down with the valve, 1. e. as, the 35 upwar valve stem 2| lS moved up and down. The valve For povger x51 valvet Fhe 2| admits fluid from an outlet duct of the acupper en 0 e Va V8 8 em as a nmmon cumulator, as later described, into operative reblock fastened thereto as by nut threaqed lation to the piston l2 for movement of the latter on the upper of the stem and forcmg up and down exactly as the valve 2 is moved the block 34 against an annular shoulder on the stem. A bell crank 36 suitably pivoted at 38 has a forked arm 39 with tines slidably embracig g 'f gg f fig fflfgf g f gg f jg fiff ing trunnion pins 40 of the block 34 (cf. Fig.3)

sistance of the speeder spring M in opposing speed adjustment The available hydraulic generally designated 44. The rock shaft 42 may thereof. Thus the power head is useful: (a) in Smtable speed ad-Justmg mater drive such as 00 plunger which supplies oil for lubrication of the head bearing. This is the principal reason for locating the cushion start servo-motor at case compnsmgi as shown magonal bore the top of the pilot valve plunger. Otherwise it sur is pp d to t e w r d la r fa f 6 It can, incidentally, be used as an interponent the plston H to ove h Piston pward a between any of the connected parts of speed Will be described present] adjustment mechanism, as between the power The power head valve 2| has a cylindrical plug head piston l2 and speeder lever U. 28 on the lower end of the valve stem 2|, which As shown in Fig. 1, a servo-motor cylinder latter does not seal the bore l! of the. piston 70 5| is made rigid with the pilot valve plunger H stem I I above the plug, whereas the plug 28 is of the ball armfinger thrust member h thereof, in sealing relation to the portion of the bore l1 and a lower speeder spring retainer or perch 52 in which it slides. As shown more clearly in includes a piston 54 fitted to the cylinder 5|. Fig. 2, the valve stem 2| is non-circular in cross- The pilot valve plunger H is centrally bored at section and thus free passages for fluid are pro- 7 55 from its lower end (lower end of bore suitably aunties plu ed). a groove I (normally at the port E) of the lower portion of the plunger H and communicates with the groove by reason of cross holes II. The groove being opposite the constant pressure port E of the pilot valve sleeve, during normal running speed of the engine, is normally continuously supplied .withhydraulic fluid under Part of'the fluid so sun- 55 is taken from said bore the plunger communicating with the bore and and the bore extends upwardly pastthe latter groove: Fluid so supplied to the wall of the valve sleeve H travels upwardly and downwardly from the groove ill in the small working clearance space (e. g. .002") between the plunger H and sleeve H. The downwardly traveling fluid is used for lubrication somewhat the'same as in saidPatent No. 2,219,229 through the intermediary of a reservoir groove 8i and flows through ducts 62, in the wall of the valve sleeve H to a lower bearing portion of the ball head. The fluid which travels upwardly along the outer surface of the valve plunger H is intercepted by reservoir groove 64 and returned to a center bore 65 leading downwardly from inside the working chamber of the servo-motor 50 into communication with the groove holes I.

At the start of the operation of the governor the piston and cylinder chamber of the servomotor ill is practically empty, fluid having been squeezed out of the chamber as slip by the force of the speeder spring M. This allows the spring to become extended so that it has initially less force to oppose outward movement of the fly balls than it has during normal operation. Thus with the speeder spring M, in effect, relieved or slacked off at the start the fly balls L quickly attain their normal operating position and begin to check the speed of the engine before it has attained full speed. But since raising of the pilot valve plunger H places the groove 56 in communication with constant pressure hydraulic system, special servo-motor 50 becomes rapidly filled with operating fluid and the effective force of the speeder spring M is then increased to normal for the particular set speed.

The working clearance of the valve plunger and sleeve between the grooves 60 and SI of the plunger H can be such as to regulate the supply of fluid to the servo-motor 50 so that the servomotor becomes filled just as the engine attains normal running speed; or suitable means for adjustably metering fluid to the servo-motor can be used (e. g. a needle valve, not shown).

To limit the capacity of the working chamber of the servo-motor 50 so that the speeder spring is always compressed the same amount by the servo-motor, leak-off vents may be provided in the wall of the servo-motor cylinder, as at 58. Alternatively. coacting shoulders (not shown) can be formed on the piston and cylinder deflnitely to limit upward movement of the lower speeder spring retainer 52 relative to the pilot valve plunger H.

During normal operation the piston and cylinder surfaces of the servo-motor 50 turn relative to each other so as not to prevent rotation of the pilot valve plunger H through engagement of the ball arms L with the thrust member h. At the start it does not matter particularly whether or not the pilot valve plunger turns in its valve sleeve H 64 through radial spring M. As a and it might not turn if the 7 means controlled by piston M is bottomed in the cylinder Ii at the start of the governing operation.

The cushion start servo-motor minated '(antifriction bearing assembly used in its location as in my said Patent 2,219,229) and a modified form of power head valve such as shown at 10 in Fig. 3 used instead of the power head. valve ii of Figs. 1 and 2. The valve 10 cooperates with the remainder of the power head ll to perform the same function as the valve 2i as well as to perform the function of the servo-motor 50 in preventing overshooting in speed upon starting the prime mover from rest to an adjusted speed.

The power head valve 10 has a cylindrical stem H which fits slidably but snugly within the axial bore il in the piston stem ii, there being no free exit paths for 'fluid'therebetween as provided between the stem 2i and the bore il in Fig. 1. Instead, a central bore 12 in extends from the neck portion having divergent branches .at this point) upwardly to near the top of the stem 1i where it intersects a through diametral bore 15. Together with the bore ii the bores 12 and II provide an exit for fluid from the chamber beneath the piston II. The fluid exit thus provided is adjustably restricted at the intersection of the bores 12 and 15 by a needle valve "threaded axially into the top of the stem 1i and held in adjusted position as by a compressible (e. g. fiber) lock washer 18.

m the operation of the modification of Fig. 3, (assuming the cylinder it remains charged with operating fluid; since the fluid cannot leave the cylinder), when the bell crank lever ll of the at the needle valve 16 does not permit the piston I: to move as fast as the valve 10 is moved. The piston l2 and the stem ii move at a speedpre determined by the adjusted position of the valve of the bell lever U is moved downwardly at a controlled rate to effect a gradual compression of the speeder result the spring M exerts a gradually increasing restrainingforce on the out-, ward movement of the fly balls L and thus the prime mover-accelerates at a controlled rate to th adjusted speed position with no tendency to overshoot. The time delay action provided by the needle valve 16 is not effective upon upward movement of the valve Ill and therefore the power head of Fig. 3 operates as in Fig. 1 when the bell crank lever 36 is moved to slow down mover.

I claim:

1. In a speed governor the combination with speed setting means, centrifugally acting means operatively adjusted by the speed setting means, and speed regulating means controlled by the conjoint action of the aforesaid two means; of hydraulically acting means operatively interposed between the speed setting means and centrifugally acting means and operable automatically at commencement of governor operation in a manner to delay the application of the force of the speed setting means at its adjusted value on the centrifugally acting means.

2. In a speed governor the combination with speed setting means including a speeder spring, centrifugally acting means operatively adjusted by the speed setting means, and speed regulating the conjoint action of the u may be elithe prime aforesaid two means; of hydraulically acting effective force exerted by the spring to cause a means operatively connected with the speeder speed regulatin operation, aspeed a the eiTective force of the spring to change speed the spring, and adjustable means to retard the 9. In a hydraulic relay speed governor mechacorresponding to a given increased speed setting nism, means arranged to commence to build up including a speeder spring and a valve member responsive means controlling the pilot valve, a

draulically acting means interposed between the acting means supplied with fluid by said first adjusting element. to cause the speeder spring to exert an increasing spring to cause a speed re ulating Operat o a nism, means for supplying the governor with hythe effective force of the spring on said pilot valve 0 a pilot valve including a shiftable valve element mencement f peration of the governor. speed responsive means in a manner to oppose 6. In a hyd u lay Speed governor the operation thereof in one direction, an adjustable bination with a speed adjusting means, a speeder speed Setting means for varying t opposing spring operatively associated with said speed adforce of the spring, hydraulically acting servojusting means and a centrifugally actuated conmotor means supphed ith hydraulic fluid trolling element of the governor. f means constithrough said shiftable valve element and internly in the speed inc g d q means bein arranged to cause the speeder spring In a Speed governor Speed Welghmg means gradually to exert an increasing force opposing including a speed r Spring and a member COYI- said speed responsive element as the operating trolled in part thereby in accordance with the efpressure is m; up by t first named means.

fective force exerted by the spring to cause a speed ALBERT K regulating operation a speed adjusting element,

and a hydraulic motion transmitting means in- 60 REFERENCES CITED terposed between said adjusting element and said spring, said last named means comprising a valve g j ig g ggigg are of record in the member arranged to be moved by said spe d adjusting element, a follow-up piston associated NITED STATES PATENTS with said valve and controlled thereby to vary the 05 Number Name Date effective force exerted by the spring, and a re- 899 569 siegmund Sept. 29 1908 stricted fluid venting means associated with the 1853'613 Herr Apr 1932 valve member in a manner to cause the follow-up 2157542 Kiese; a 1939 m t n of the piston to be slowel" in the direction Kalin o t 27I to increase speed than to decrease speed. 2324514 Kaun ""Z'; July 1943 8. In a speed governor, speed weighing means 2324515 Kaun July 1943 including a. speeder sprin and a member con- 2:325:009 Kan m 1943

Images