US2747426A - Engine speed control mechanism - Google Patents

Description

May 29, 1956 Filed Oct. 16, 1952 R. R. ROBINSON 2,747,426

ENGINE SPEED CONTROL MECHANISM 2 Sheets-Sheet l INVENTOR.

fiana/a lfoA/mmv ATTORNEY y 9, 1956 R. R. ROBINSON 2,747,426

ENGINE SPEED CONTROL. MECHANISM Filed Oct. 16, 1952 2 Sheets-Sheet 2 IN V EN TOR.

AT T 0RNEY United States Patent Oflice 2,747,426 Patented May 29, 1956 ENGINE SPEED CONTROL MECHANISM Ronald R. Robinson, Morton, 111., assignor to Caterpillar Tractor Co., Peoria, 111., a corporation of California Application October 16, 1952, Serial No. 315,054

2 Claims. 01. 74--507 'This invention relates to control means for use on angine governors and the like and is disclosed herein in its application to a spring balanced governor of the kind generally employed in connection with engines of the compression ignition type.

There are various applications of engines in which a certain operating speed is determined as ideal and there is little or no requirement for operation at any other speed. For example, an engine employed for driving a pump or electric generator set must operate at a given speed which is critical in that it is required for an exact output of fluid pumped or electrical energy generated. This speed is usually somewhat less than the maximum rated speed of the engine and for convenience may be referred to as operating speed.

The present invention contemplates the provision of governor or speed control mechanism for an engine in which a manual control lever may be accurately set at a certain operating speed then moved to shut down posi tion and thereafter quickly returned to precisely the same operating position for which it was originally set.

It is the object of the invention to provide a control for a governor or the like with a manual control element having means for holding it in a fixed position and with a vernier adjustment for varying the speed of operation of the engine while the lever occupies said fixed position. A further Object is to provide such means in a structure which will enable convenient adjustment and will permit the control element to be freely moved between its engine shut down position and the adjusted operating position. Further and more specific objects and advantages of the invention are made apparent in the following description wherein the invention is described in detail by reference to the accompanying drawings.

In the drawings:

Fig. 1 is a view in front elevation of an engine governor control and a portion of the governor mechanism controlled thereby with parts broken away to disclose certain features of construction,

Fig. 2 is a bottom plan view of the governor control mechanism illustrated in Fig. 1 as viewed from the line H-II in Fig. l and with parts broken away, and

Fig. 3 is a sectional view of the governor control mechanism taken on the line IIII1I of Fig. 1 but with a portion of the governor spring and upper anchor therefore added.

To illustrate the invention, a conventional governor spring is shown at as connected in tension to a lever 11 fixed to a shaft 12. Also fixed to the shaft is a lever 13 connected at its end with a fuel supply control member 14, such, for example, as the rack bar which adjusts fuel pumps to vary the volume of fuel directed to an engine. The lever 13 carries a roller 15 engageable by a sliding thrust collar 16 which is influenced by conventional fly weights (not shown) to swing the lever 13 and rack bar 14 toward engine shut down position as the fly weights swing outwardly in response to operating speed. The tension of the spring 10 tends in the conventional manner to oppose the action of the fly weights and maintain the engine in operation. Therefore, the engine speed is controlled by varying the tension of the main governor spring It To vary this tension, the upper end of the spring is anchored as by a bolt 17 to a lever 18 fixed against rotation by means (not .shown) on a shaft 19.

The shaft 19 may be rocked to vary the tension of the spring 10 by means of a control lever which is connected with the shaft through the medium of a case 20 having a cover 21 thereon and also through Vernier adjusting mechanism in the case. The control lever comprises a shaft 22 rotatable in a suitable bore in the case and having a knurled knob 22a at one end so that it may be rotated by hand. At its inner end, the shaft 22 carries a worm 23 meshing with a Worm gear segment 24 fixed against rotation on the shaft 19 by a spline connection and a clamping screw 25. Back lash between the worm and worm gear is taken up by a spring 26 and thrust cup 27 which bears against the end of the Worm 23. The spring is seated against a plug 28 tightly fitted in the end of the bore which releases the worm.

As best shown in Fig. 3, the case 20 is mounted for rotation about the hub of the worm gear segment 24 but is held against such rotation by the meshed engagement of the segment 24 with the Worm 23. The shaft 19 is carried for rocking movement in a bearing 29 formed in a plate 30 secured, as by cap screws 31, to a wall 32 partially shown and which is a part of the housing enclosing the governor mechanism.

With the mechanism thus far described, the tension of the governor spring 10 may be varied by swinging the knob 22a about the axis of the shaft 19 to rock the shaft. An 'arcuate track 33 is formed as a part of the plate 39 and has a latch socket 34 adjacent one of its ends. A spring pressed latch pin 35 is mounted in a boss 36 on the case and is urged by a spring 37 into frictional contact with the track 33 over which it slides as the control lever is manipulated. When the control lever reaches the position corresponding to maximum rated engine speed, that is counterclockwise of the position illustrated in Fig. l, the latch pin enters the rocket 34 and the lever is thereby locked against further rocking movement in either direction. Retraction of the latch pin is accomplished by a retracting lever best shown in Figs. 1 and 2 at 38. This lever is pivoted to the case as by B. pin 39 and has a bifurcated end 40 embracing the latch pin for retracting it when the end of the lever is depressed. The end of the lever is conveniently arranged for operation by the thumb of the hand which grasps the knob 22a.

In the operation of the device thus far described to establish a locking position for the governor setting the engine is first started and the control mechanism is moved to maximum rated speed position with the latch pin 35 engaged in its socket 34. The speed of the engine is then reduced by rotation of the knob 22a which, through the vernier control afforded by the Worm and quadrant, rocks the shaft 19 and adjusts the tension of the governor spring 10 without varying the position of the case 20 which is latched against movement. Suitably positioned pins 41 in the case 20 limit the movement of the segment 24 so that it cannot move beyond the position where it meshes with the worm. Now with the required engine speed established, the case 20 is latched in the correct position for producing that speed. Consequently the latch pin may be released and the engine shut down and, so long as the knob 22a is not rotated, the case may be returned to the same position without difiiculty. When the engine is again started, it is simply necessary to swing the governor control lever to the position where it is automatically latched for the desired operating speed.

The use of this invention obviates the necessity of reestablishing an operating position which is frequently a tedious procedure each time the engine is started and also provides .a Vernier adjustment to be .used in the original establishment of the operating positionf 'I claim:

t-LIIn'an engine speed control mechanism which includes a shaft to vary engine speed upon rocking motion, a worm and gear assembly associated with the shaft, a control'lever to rock the shaft by swinging said assembly as :a unit, means on the control lever to rotate the worm to rock the shaft while the unit, is stationary, and means to'flatc'h the assembly against swing'ingrnovement during such rotation of the worm whereby a required engine speed ,may be established by rotation of the worm and reestablished 'by subsequent return of the assembly to its latched position.

2L ,Inran englne speed control mechanism which includes a shaft to vary engine speed upon rocking motion,

4 g v a worm gear fixed to said shaft, a case enclosing said gear and rotatable about the axis of said shaft, a lever rotatably mounted in said Zcase, a worm on the lever meshing with said gear, and a releasable latch to hold the case against rotation whereby said shaft may be rocked by rotating said lever while the case is latched and rocked by swinging said lever and case when the case is released.

7 References Cited in the file of this Patent 7 UNITED STATES PATENTS

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