US3534660A

US3534660A - Hydraulic servo governor

Info

Publication number: US3534660A
Application number: US799214A
Authority: US
Inventors: Stephen F Glassey; Fredrick W Pfeiffer; Harold C Davidson
Original assignee: Caterpillar Tractor Co
Current assignee: Caterpillar Inc
Priority date: 1969-02-14
Filing date: 1969-02-14
Publication date: 1970-10-20
Anticipated expiration: 1987-10-20

Description

United States Patent Stephen F. Glassey East Peoria;

Fredrick W. Pfeiffer, Peoria Heights; Harold C. Davidson, East Peoria, Illinois 172] lmentors [21] Appli No. 799,214 [22] Filed Feb. 14, 1969 [45] Patented Oct. 20, 1970 Caterpillar Tractor Co. Peoria, Illinois a corporation of California [73] Assignee- [54] HYDRAULIC SERVO GOVERNOR 5 Claims, 3 Drawing Figs.

91/458 511 lnt.Cl ..F15bl3/l6 so FieldofSearch 91/458 [56] References Cited UNITED STATES PATENTS 1,748.326 2/1930 Birmann 91/366 3,002,502 10/1961 Szydlowsk' 91/366 3145,624 8/1964 Parks et a1. i t 1 1 1 91/366 Primary ExaminerEdgar W. Geoghegan Almrncy- Fryer, Tjensvold, Feix Phillips and Lempio ABSTRACT: A hydraulic servo governor for regulating en gine speed having rotating flyweights acting against an adapter secured for rotation with a valve member reciprocahly disposed in a cylindrical bore. A member seating a spring which tends to oppose the effect of the flyweights is rotatably secured for longitudinal motion with the valve and adapter by means ofa thrust bearing.

Patented Get. 20, 1971) 3,534,660

Sheet 1 of 2 INVENTORS LO STEPHEN F GLASSEY FREDERICK W. PFEIFFER BY HAROLD C. DAVIDSON W) {M1 w 2% #411- ATTORNEYS Patented Oct. 20, 1970 3,534,660

Sheet 2 of2 J l &

INVENTORS STEPHEN F. GLASSEY FREDERICK W PFEIFFER BY HAROLD C. DAVIDSON HYDRAULIC ssnvo GOVERNOR The present invention is described with reference to a hydro-mechanical governor of the type described in U.S. Pat. Nos. 3,145,624 and 2,961,229 issued respectively on Aug. 25, 1964 to J. H. Parks et al. and on Nov. 22, I960 to .l. H. Parks, both patents being assigned to the assignee of the present invention.

Governors for controlling engine speed commonly operate through the interaction of flyweights and an opposing governor spring. The flyweights are mounted on a member which rotates at a speed proportional to the engine speed. The flyweights assume a position consistent with the centrifugal force supplied by the rotating member and thereby determine the position of a fuel control member such as an engine fuel pump rack bar. Constant speed operation is achieved when the rack bar is positioned to supply fuel to the engine to operate it at a speed which rotates the flyweights with sufficient centrifugal force to counteract the opposing governor spring.

In certain engine applications, for example, where the governor is employed to regulate the speed of a diesel engine driving a generator, it is necessary to utilize a governor which will rapidly respond to a load change without excessive hunting. The term hunting," as here employed, refers to a condition which exists when the engine load is suddenly increased or decreased. The governor, in attempting to compensate and maintain a constant speed, often overshoots the set speed and then, in returning toward the set speed, undershoots the set speed. This hunting action continues in diminishing cycles until the governor stabilizes. If the governor continues to oscillate or hunt for too long a time, it is detrimental to the operation of the generator.

Such governors commonly comprise a cylindrical control valve which is caused to move longitudinally in a cylindrical bore and position the fuel pump rack bar according to the interaction of flyweights and a spring. One cause or contributing factor to the hunting condition described above is the additional force required to initially set the control valve in longitudinal motion while such motion is resisted by static friction between the control valve and the cylindrical bore in which it is disposed.

The present invention eliminates this static friction and thus reduces the hunting tendency of the governor and improves governor response by permitting substantially free and independent rotation of the control valve within its cylindrical bore.

The present invention offers particular operating advantages when embodied within a governor of the type disclosed in U.S. Pat. No. 3,145,624. As disclosed in that patent, the control valve is associated with a hydraulic servo unit which assists in positioning of the fuel pump rack bar. The hydraulic servo unit substantially reduces the amount of force exerted through the control valve. The elimination of static friction accordingly reduces hunting in the governor by a greater degree.

In addition, the present invention permits generally free and independent rotation of the valve to increase responsiveness of the governors. This feature tends to reduce wear in those parts of the governor which are associated with the control valve, thus enabling the governor to maintain an accurate setting over long periods of operation.

Other objects and advantages of the present invention will be apparent from the following description and the accompanying drawings.

In the drawings:

FIG. 1 is a side view, with parts in section, of a hydromechanical governor which embodies the present invention;

FIG. 2 is an enlarged fragmentary view taken from FIG. 1 to illustrate in detail a portion of the governor with which the present invention is particularly concerned; and

FIG. 3 is a view taken along section line Ill-III of FIG. 2.

As illustrated in FIG. 1, a governor 11 controls the longitudinal position ofa fuel pump rack bar 12 and accordingly the LII adjustment of fuel pumps, one of which is illustrated at 13, through a segment gear [4 associated with each fuel pump and interacting with the rack bar. The fuel pump is preferably illustrative of a diesel engine driving a generator. The governor is enclosed by a governor housing 16 and a fuel pump housing 17 and comprises flyweights l8 pivotally mounted on a cylindrical carrier 19 by pins 21. The carrier is mounted for rotation about a cylinder 22 affixed to the fuel pump housing. The cylinder 22 forms gear teeth as indicated at 23 to provide a pinion in constant mesh with a drive gear 24 secured to a shaft 26 which forms a part of the timing gear train of the engine.

The flyweights move outwardly under the influence of increasing engine speed so that their radially inwardly extending arms 27 act against and tend to cause leftward motion of a generally tubular adapter 28 and a control valve 29 secured thereto by a pin 31. Leftward motion of the adapter 28 and valve 29 is resisted by a spring 32 acting against a valve seat 33 associated for longitudinal motion with the adapter and valve 29 in a manner described below in detail. Thus, when engine speed is increasing, the flyweights move outwardly and their radial arms 27 act against the adapter to overcome the spring 32 to cause leftward movement of the control valve. Conversely, when engine speed is decreasing, the flyweights move inwardly and the spring 32 tends to return the adapter and control valve to their rightward positions.

A servo system 34 is associated with the control valve and positions the rack bar in response to longitudinal movement of the control valve. The servo unit comprises a piston 36 disposed for longitudinal motion in the fixed cylinder 22 and within a fixed sleeve 37 while its right end 38 is joined to the fuel pump rack bar 12. The control valve 29 is disposed for longitudinal motion within a bore 40 formed by the piston 36. The piston has a flange or piston head 39 midway along its length forming an annular cavity 41 within the left end of the fixed cylinder 22 and enclosing an annular cavity 42 between the right end of the fixed cylinder 22 and the fixed sleeve 37. Hydraulic fluid is introduced into the annular cavity 42 through a conduit 43 to act against the right side of the piston head and to be communicated to the piston bore 40 by a conduit 46 in the piston head. The piston head has a conduit 47 communicating the annular cavity 41 with an annular recess 48 in the piston bore. The control'valve defines a first annular slot 49 and a rightwardly disposed second annular slot 51 which is communicated to a fluid drain formed by internal bores 52 and 53 in the control valve and fuel pump rack bar respectively.

In operation, the piston 36 tends to follow longitudinal movement of the control valve and to position the rack bar accordingly. As the control valve is moved rightwardly, the annular slot 49 completes a fluid path from the annular cavity 42 through the conduit 46, the annular recess 48 and the conduit 47 into the annular cavity 41 wherein fluid pressure builds up to act against the piston head and move the piston and fuel pump rack bar to the right. As the control valve is moved leftwardly, the annular slot 51 is aligned with the annular recess 48 and permits fluid from the annular cavity 41 to pass to drain through the conduit 47, the annular recess 48 and the internal bores 52 and 53. Upon reduction of fluid pressure in the annular cavity 41, hydraulic fluid pressure in annular cavity 42 acts leftwardly against the piston head to cause leftward movement of the piston and rack bar until the annular slot 51 is no longer in communication with the annular recess 48.

A flanged control rod 54 penetrates a hole 55 formed in the left end of the spring seat 33 and extends leftwardly therefrom to act against a spring blade 56 by means of a plate 57 secured upon the control rod to allow additional fuel to be injected into the engine to provide the torque rise required from the engine under certain conditions.

To permit adjustment of the governor and the speed at which the engine is to be controlled, the spring 32 is retained at its left end by a slidable spring seat 58. A manually adjustable lever 59 acts against the spring seat 58 to control its longitudinal position and thus control the force which the spring 32 exerts upon the valve seat 33, the adapter 28 and the control valve 29. The manner of operation of the lever'59 is fully described in US. Pat. No. 2,961,229.

The present invention is concerned with improving response of the control valve 29 and the servo unit 34 to variations in engine speed and corresponding repositioning of the flyweights 18. This problem is believed to be solved by the present invention in a novel manner which affords additional operating advantages for the governor.

As noted above, the valve 29 is secured for rotation with the adapter 28. When the flyweights are rotated and their arms 27 act on the adapter, the adapter 28 and valve 29 are accordingly both rotated along with the flyweights. Constant rotation of the valve 29 within the bore 40 during operation of the governor eliminates static friction therebetween which tends to resist initial motion ofthe valve in either direction.

Additionally, the present invention further improves response, reduces wear and assures more uniform operation of the governor by arranging the valve 29 and adapter 28 for generally free rotation in response to the flyweights. With the small adapter 28 being the only component which is rotated with the valve, the rotating mass of the valve 29 is minimized and its responsiveness is further reduced.

The interconnection between the spring 32, flyweights 18 and valve 29 substantially eliminates rubbing engagement between relatively rotating parts except for that between the valve 29 and the bore 40. This in turn prevents wear in the governor which would otherwise tend to cause undesired variation in the engine speed setting established by the governor.

The features which accomplish the improved operating characteristics discussed above are best seen in FIGS. 2 and'3. Referring to those FIGS. as well as FIG. 1, a ball bearing assembly 61, preferably of a type for transferring axial thrust, is

arranged between the seat 33 and valve 29. The bearing has an inner race 62 secured to an end of the valve 29. its outer race 63 is secured to a cylindrical end portion 64 of the spring seat 33. The end portion 64 also has a flange 66 for supporting the spring 32.

Since the bearing 61 provides an almost frictionless coupling between the valve 29 and spring seat 33, the valve 29 and adapter are capable of free and independent rotation except for contact between the valve 29 and bore 40. In addition to permitting relatively frictionless rotation, the bearing also couples the spring seat 33 and valve 29. Thus, reciprocating interaction of the flyweights 18 and spring 32 is imparted to both the valve 29 and the control rod 4 To facilitate assembly of the governor and to adapt the present invention to existing governors, the end portion 64 is formed with two

separable segments

33a and 33b. The spring seat 33 may be manufactured as a single piece and then cut to form the two segments. With the two segments arranged about the valve 29 and bearing 61, they are secured together by a spacer 67 and a snap ring 68. The inner bearing race is also secured .to the adapter 28 by a snap ring 69 as best seen in FIG. 1.

We claim:

1. in a governor of the type having flyweight means interacting with a spring to longitudinally position a control valve within a cylindrical bore formed in a housing and hydraulic servo means responsive to the positioning of the control valve for establishing engine speed, the combination comprising:

an adapter secured for rotation with the control valve, the

adapter being disposed for interaction with the flyweight means and for rotating the control valve together with the flyweight means;

a seat member upon which the spring acts; and

bearing means arranged to effectively'secure the spring seat and control valve together for longitudinal motion and provide for proper interaction of the spring and flyweights while permitting effectively free and independ ent rotation of the control valve and adapter by the flyweights.

2. The invention of claim 1 further comprising a control member rotatably secured to an end of the seat member opposite the control valve.

3. The invention of claim 1 wherein a tubular end of the seat member surrounds an end of the control valve, the bearing means being a thrust bearing arranged between the tubular seat member portion and the control valve.

4. The invention of claim 3 wherein the spring abuts the seat member and urges it toward the valve bore housing, the adapter having an annular surface adjacent the valve bore housing, the flyweight means having inwardly projecting arms which tend to be urged against the annular surface by rotation of the flyweight means.

5. The invention of claim 3 wherein the tubular seat member end has an increased diameter relative to adjacent portions of the seat member, the tubular end being formed of generally diametrically segmented portions and further comprising means for securing the segmented portions together.