US2503362A - Governor with built-in overspeed trip - Google Patents

Description

April M, 1950 F. H. SWEET GOVERNOR WITH BUILT-IN OVERSPEED TRIP Filed Feb. 12, 1949 INVENTOR. 2 0/0 H. 5 WE E 7- BY ATTU PA/EV Patented Apr. 11, 1950 TRI Floyd H. Sweet, Euclid, Ohio, assigns to The Marquette Metal Products Company, Cleveland, Ohio, a corporation of Ohio Application February 12, 1949, Serial No. 76,052

The invention relates to an improved hydrau lically acting overspeed governor (hereinafter overspeed trip) and to an improved hydraulically acting combination speed regulating and overspeed trip governor mechanism supplied with operating fluid from a common source without sacrifice of certainty or safety of operation and without possibility of the regulating part of the mechanism interfering with the trip part and vice versa. The above indicates the general objects.

The speed regulating or main governor mechanism herein shown schematically (left part of Fig. l principally) is substantially according to A. Kalin Patent 2,219,229, October 22,1940; being arranged (e. g.) for isochronous governing of Diesel engines. As in'the patent a 'flyweightoperated pilot valve controls admission of substantially constant pressure 'fluid'in respect to a double acting, differential type, engiHe-fueI regulating servo-motor, the constant pressure fluid being admitted to a relatively large servo-motor piston area thereof to increase engine fuel supply and to a relatively small area of the same piston to reduce and cut off the fuel supply. The overspeed trip mechanism hereof has a special-flyweight-operated, normally closed master'valve controlling a branch conduit for 'the constant pressure fluid and, when overspeed occurs, the master valve effects admission of said fluid to a trip or slave valve mechanism which causes engine shut-down b venting all the fluid from operating contact with the relatively large area of the engine-regulating servomotor piston whereupon the constant pressure fluid maintained in contact with the relatively small area of the servomotor piston moves said piston quickly to its fuel-off orno-fuel position and there retains it. The trip mechanism has provision for temporary manual emergency or testing control of the tripping ac tion, as when an attendant is at hand and can keep the engine within a safe operating speed regardless of its tendency to overspeed and reoperate the trip mechanism. Also provision is' made (two exemplary forms shown) whereby any I constant pressure fluid which may leak past the master trip valve while the speed regulating gov ernor mechanism is properly in control of the engine cannot operate the slave valve and cause undesired shutting down of the engine. The discussion of this paragraph indicates more specific objects of the invention. Others will be brought out in the following description of an illustrative form of the invention.

In the drawing, Fig. l is a schematic. view showing essentially the entire governor and trip- 9 Claims. (01. 121-42) mechanism; Fig; 2 is a fragmentary view showing the -5position of the overspeed trip fiyweights when tripping or engine shut-down is called for; and Fig; 3 is a relatively enlarged detail central sectional-assembly view of a preferred form of an overspeed trip latch and manual control or reset valveof the overspeed trip mechanism as actually arranged in a typical installation.

.Referring to Fig. 1, the isochronous governor fiyball mechanism "generally designated A has a speeder spring Boperatively. connected with a governor pilot valve plunger C at a thrust plate 0 thereon through which the speeder spring acts downwardly against arms of the pivoted flyweights at tocontrol governor ports D and E which normally or during steady state are closed by landed and -e respectively of the valve plunger. Fluid is supplied-by a gear pump F such as shown in the Kalin patent, the output line or-duct G of justing-systemaslusual (e'. g. to the injector racks incase of a Diesel engine). 'A valve chamber 0' formed principally. by a neck portion of the pilot valve: plunger C communicates through a regulating fluid duct K with the servomotor J partly through the slave valve- I'of the overspeed trip portion ofthe'mechanism (right; Fig. 1) tube described later. 'K' indicates'the portionof the' duct K which leads from the slave valve l to the servomotor cylinder so that the regulating fluid acts against the relativel large'efiective area L of the piston I. i

Operation of the piston I in the indicated fuelon'direction results from lowering of the pilot valve C, as during increased loading of the engine (flyweights moving inwardly) the pilot valve land d then opening port D to enable constant pressure fluid from duct G to flow through ducts K and K to area L forcing the piston I to the left due to the difference 'in areas H and L. Movement of the piston I'in the fuel-off direction as when the" engine load is decreased (causing outward movement of the flyweights) results from raising of the pilot valve plunger C thus dumping regulating fluid from operating contact with the larger piston face L through the port E- as will be apparent.

The duct G compensation fluid duct with a sump portion of the governor fluid reservoir. "7

Referring to the overspeedtrip portion of the;

mechanism, a branch portion 2 of the constant pressure fluid duct G leads toa valve'boreij.

which may be formed in a special section 4 pf the governor power case, the branch 2 intersect ing the bore 3 between "its ends. The bore 3 is slidablyoccupied'by themaster trip valve plunger 5 having an upper land 6 normally maintained in closing relation to'an'outlet port-or passage 1 against the action of a biasing spring 8 at the bottom of the plunger tending to raise the plunger and open the port. An actuating rod" I ll for the master valve plunger 5 rests on athrust ball H in an axial socket at the top of the plunger, the rod being freely supported 'in' the axial bore of 'a rotary head [2 which in mm is suitably mounted for free rotation as on bearings (3 in a bracket l4 located above the power 'c'ase section 4. The upper end of the 'actuatingro'd' is suitably connected to a thrustpl'ate l5of; the A counterpoise trip "'flyweight mechanism 16. M spring l8 in a tubular casing 20 fixed 'to'the top of the rotary head [2 acts through the thrust plate l5 initially to hold a paii"'of flyweightslT in the position illustrated in Fig. 1. Adjustment of the pressure of the spring I8 is afforded by'a" threaded cap piece 2| in the casing 20'.

The head l2 of the flyweight mechanism 16' is rotated through the intermediary'of gear teeth 22 on its lower end portion which are in constant mesh with teeth on' any suitable rotary part of the speed regulating governor me'chanlsmffor in stance teeth on the ballheadinot shown) which supports the flyweight mechanism A; Prefer ably the rotary head l2 ofthe trip 'mechanism' isiturned two or three times as fast as' the main" governor head so that the massof'the flyweights I! can be relatively small but still be adequately sensitive in operation'at theadjusted overspeed' r tripping point. v The counterpoise spring l8 is of'ordinary" coil spring form and when the flyweights move with increased rotational speed of the head "l2 from' their inwardly inclined position (Fig. 1) into approximately vertical position (not shown) the increasing spring resistance to ou'tward'move-' ment is not enough to keep pace witnthe increased effective cehtrif-ugal'forcedue to the'increased radius; and the fiy'wei'ghts movequ'ickly' from (e. g.) vertical into'the limited outward position (Fig. 2) wherein the lower arms of'the flyweights may be stopped by'engagem'ent with" thelower rim of the spring casing 20.

Wherrthe actuating rod lfllises approximately.

4 a chamber 28, the lower end of which is defined by a counterbore 29 in the casing section 4. The slave or trip valve plunger 30 has a spring 32 below it which normally maintains an upper end or piston portion 3| of the plunger against the shoulder provided by the bottom (literally top) of the'counterbore 29. The piston portion 3! may be of considerably less diameter than the counterbore to avoid having to align the plunger therewith.

The guide for the slave or trip valve plunger 30' is'a' sleeve '34 seated tightly in a portion or section 35 of the governor power case and formed top'rovide an inlet port 36 communicatin with the regulating fluid duct K and two outlet ports, one" 9.15 31 normally communicating with the portionK' of said duct K leading to the larger face I L'of the piston I and the other, at 38, leading teeny suitable sump or negligible pressure portion of the governor housing. In the illustrated position of the slav or trip valve plunger 30, passages K and K" communicate so that the engine is fully under control of the fiyweight mechanism A. The'piston portion 3| of the plunger 30 slidably flts the upper end of the receivin bore for it in the'ported sleeve 34.

The tripping or engine-stopping operation results from rise in pressure of fluid in the chamber 28 abov the slave valve plunger 30 thefluid acting onthe piston portion 3| of the plunger tomove the plunger downwardly until a land portion 40 thereof (just'below the piston portion 3|) closes the port 36 of duct K and a lower land 41 of the plunger opens the sump communicating '5 port 38. When thelatter port m opened, pressure which'has been maintained against the large face L of 'the piston by action'of the main overnor pilot valve C is dumped from the servomotor cylinder. Constant pressure from the lines G and "G' then moves the servomotor piston I in the fuel-off'direction and to the end of the possiblepiston stroke, shutting down the engine.

Referring further 'to the master or actuator valve 'plunger 'of the overspeed trip, that plunger must be reasonably free in its bore 3 in order to bebertain of operation at all times, hence the upper land6 of the plunger cannot be too tightly fitted into the-bore. The'plunger, incidentally, is raised from its initial position during governor 50? operation due to play of the flyweights ll between-their initial inwardmost position and a vertical or nearly vertical position but insufficiently outward to cause tripping. Thus the plunger 5 is'not likely to be friction-bound as by :accumulations of foreign matter in the hydraulic fluid. Leakage of hydraulic fiuid past the plunger 5 during the time the main governor is in controlcangradually slip past'the check valve into the'chamber 28 and, unless special provision made as hereinafter described to prevent it, such leakage or slip can cause untimely operation of-the overspeed trip by depressing the slave valve plunger 30. To prevent that from occurring, normally expected seepage'past the plunger I 5 and 'check valve 25 is vented through an axial duct 45 in the plunger and connected radial orifices opening into a ring cavity 46 of the plunger. Cooperating passages 41 in the sleeve 34 and case section lead to the sump. When full accumulator pressure is admitted to the chamber 28 by operation of the overspeed trip fiyweights l1 and valve 5, there is always a sufficient volume of fluid acting against the plunger pistonl3l' to render the drainage normally af- 1 forded by the passages -4! insignificant. Full downward movement of the slave valve plunger 30 at proper times is thus assured. When the ring cavity 46 passes the ports afforded by passages 41 those passages are sealed by the piston portion 3| and no further drainage is possible, hence fluid trapped in the chamber 28 by the check valve insures maintenance of the trip mechanism (i. e. slave valve in engine stopping operation.

An alternative restricted venting means for fluid which may slip past the master valve plunger 5 is shown in Fig. 3 wherein the passage leading to the check valve 25 is vented to sump by an inverted L-shaped passage 49, the upper end of which is normally open to discharge the leakage fluid into the open top of the bore 3 for the plunger 5. Just before the latter is pushed up by the spring 8 far enough to open the port or passage 1 the passage 49 is closed by upper valve plunger land 5 as will be apparent so as not to interfere with the tripping operation of the mechanism I.

When it is desired to render the trip mechanism hereof temporarily or continually inoperative,.-as when an attendant is at hand to make sure that the engine will not race or reach a dangerous overspeed, such attendant depresses a spring returned plunger 5!], Figs. 1 and 3, movably carried by the main governor case and with its inner reduced end or pin portion 51 aligned for contact with a pressure release check valve ball 52. The plunger 50 extends through a seal 53 (Fig. 3 only). When the chamber containing the two check valves 25 and 52 is vented to sump by opening of the valve 5 the slave or trip valve 30 is returned to its normal or raised position by its spring 32 and the main governor can then take control of the engine by resupplying the regulating servomotor J through passages K and K and otherwise performing as previously described.

I claim:

1. In combination with a hydraulic relay speed regulating engine governor having a pilot-valvecontrolled servomotor of the differential piston area type, wherein pressure fluid controlled by the pilot valve is admitted selectively into operating contact with a relatively large piston area of the servomotor to increase engine fuel and released from operating contact therewith to decrease and shut off engine fuel, a hydraulically acting overspeed trip centrifugal governor mechanism operatively connected to the same pressure source as that of the speed regulating governor and having a master valve which, on overspeeding of the engine, diverts fluid from said source to a slave valve which in turn dumps the fluid from operating contact with said relatively large piston area to shut down the engine.

2. In combination, a hydraulic relay speed governor wherein a pilot valve and cooperating means responsive to speed changes of a governed machine controls admission to and venting of operating fluid in respect to a relatively large eflective area of a speed-regulating servomotor having a relatively smaller opposite eflective area continually exposed to substantially constant pressure fluid, a hydraulically acting overspeed governor mechanism having overspeed responsive means controlling a normally closed master valve arranged to admit such constant pressure fluid to a spring biased slave valve, the latter being operable as a piston by the constant pressure fluid admitted thereto to dump fluid from operating contact with the relatively large eflective area of the servomotor. i

3. The mechanism according to claim 2 including a spring closed check valve between the master valve and slave valve to maintain the slave valve in an operating position against the spring biasing force thereon.

4. In a hydraulically acting speed governor, a speed regulating hydraulic relay governor mechanism including a two-way hydraulically actingservomotor piston and cooperating opposed fluid chambers and speed responsive valve means selectively subjecting the servomotor piston through respective chambers to operating fluid pressure for movement of the piston in opposite directions, an overspeed governor speed responsive mechanism including speed responsive means interconnected with the aforesaid speed responsive means for operation concurrently therewith at all times, a common fluid supply for both mechanisms, a master valve operated by the overspeed responsive means to divert fluid from said source, and a slave valve operable to dump operating fluid from one chamber of the servomotor, the slave valve including a plunger having a piston portion exposed to pressure from said source by operation of the master valve to causethe fluid dumping operation.

5. In a hydraulically acting speed governor, a speed regulating hydraulic relay governor mechanism including a two-way hydraulically acting servomotor piston having opposed operating chambers and speed responsive valve means selectively subjecting the servomotor piston through respective chambers to operating fluid pressure for movement of the piston in opposite directions, an overspeed governor speed responsive mechanism including speed responsive means interconnected with the aforesaid speed responsive means for operation concurrently therewith at all times, a common fluid supply for both mechanisms, a master valve operated by the overspeed responsive means to divert fluid from said source, a slave valve operable to dump operating fluid from one chamber of the servomotor, the slave valve including a plunger having a piston portion and cooperating cylinder exposed to pressure from said source by operation of the master valve to cause the fluid dumping operation, and restricted v'ent means for said cooperating cylinder controlled by said piston portion of said plunger so that the vent is closed when the slave valve plunger is in its fluid dumping position.

6. A hydraulic overspeed governor mechanism for engines, comprising a rotary head with spring biased flyweight means thereon, a master valve including a valve plunger operatively connected with the flyweight means and cooperating inlet and outlet ports, the former connected with a source of fluid pressure, said plunger having an inactive or normal position blocking one of the ports, a slave valve including a spring biased valve plunger operable from an inactive position to an active position wherein it can initiate and cause an engine shut-down operation, the slave valve plunger having a piston portion and cylinder therefor, the cylinder being connected with said outlet port of the master valve for operation of the slave valve plunger into its active position, a normally restricted vent between the master valve and the cylinder to prevent accumulation of operating fluid which may slip through the master valve in its inactive or normal position from operating the slave valve plunger, one of omma said valve plungers operating to closethe vent in the active position of that plunger.

7; A hydraulic overspeed governor mechanism fonengines, comprising a, rotary head with spring biased flyweight means thereon, a master valve including a valve plunger operatively connected with the flyweight means and cooperating inlet and outlet ports,- the former connected with a source of fluid pressure, said plunger having an inactive or normal position blocking one of the ports, a slave valve including a spring biased valve plunger operable from an inactive position to arr-active position wherein it can initiate and cause any engine shut-down operation, the slave valveplunger having a piston portion and cylindertherefor, the latter being connected with said outlet port of the master valve for operation of the slave valve plunger into its active position, a normally restricted vent for the cylinder to prevent accumulation of operatin fluid which may slip through the master valve in its closing position from operating the slave valve plunger, said slave'wvalve plunger operating to close the vent in the active position of the slave valve plunger.

8. The mechanism according to claim 6 wherein there is a spring closed check valve between the master valve and cylinder, the restricted vent isbetween saidmutlet-port of themaster valve and the check valve, and the master valve plunger closes the vent. 7

- 9. The mechanism according to claim 6 wherein a valve chamber is interposed between the the chamber to render the overspeed governor mechanism inactive.

FLOYD H. SWEET.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,219,229 Kalin Oct. 22, 1940 2,328,451 Hedman Aug. 31, 1943 2,338,548 Sheppard Jan. 4, 1944 2,344,308 Kalin Mar. 14, 1944 2,440,844 Bryant May 4, 1948

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