US2168372A - Centrifugal governor - Google Patents

Description

W. T. TABB CENTRIFUGAL GOVERNOR Aug. 8, 1939.

Filed eb. 2,5 1957 INVENTOR WARNER TI TABB BY HIS ATTORNEYS Patented Aug. `8, 1939 UNITED STATES CENTRIFUGAL GOVERNOR Warner T. Tabb, Brooklyn, N. Y., assignorto Eisemann Magneto Corporation, New York, N. Y., a corporation of New York Application February 26, 1937, Serial No. 127,994

12 Claims.

This invention relates to centrifugal governors and more particularly to centrifugal governors for the fuel injection pumps of internal combustion engines and it is an object of this invention to provide an Iimproved governor of the typedescribed which Will be suitable for engine control at low .as well as high speeds and which will maintain the engine speed within given limits from no load to full load thereon irrespective of whether the speed for which the governor is set is low or high. It is also an object of this invention to provide a centrifugal governor of the -class described of such construction that it will function equally Wellin either the vertical or horizontal position and at all speeds without any tendency of the weights to chatter or contact` with the supporting and driving shaft.A It is also an object of this invention to provide an improved arrangement of centrifugal unit, fuel control valve and spring which will permit of their being incorporated in the fuel pump casing Without necessitating a casing of objectionable size and it is a further object of this invention to provide a spring of improved construction having characteristics which render it particularly applicable for use in connection with a centrifugal unit.

In the drawing in which is illustrated a preferred embodiment of this invention- Fig. 1 is a partial vertical sectional View of -a fuel pump for internal combustion engines showing in elevation a centrifugal unit and its associated parts constructed in accordance with this invention; l Fig. 2 is a top plan view of the centrifugal unit shown in Fig. 1;

Figs. 3 and 4 are vertical sectional views taken as on line 3--3 of Fig. 2, Fig. 3 showing the centrifugal unit as at rest or inoperative and Fig. 4 showing the centrifugal unit in operation with the weights at substantially the limit of their outward movement; and

` Fig. 5 is a fragmentary vertical sectional view of the centrifugal unit shown in Fig. l, the view being taken on the longitudinal axis and at right angles to the views of Figs. 3 and 4.

In the drawing the invention is shown in connection with a fuel pump for `internal combustion engines, for the purpose of illustration, but it is to be understood the invention is not to be limited to such use. 'I'he fuel pump shown is of the type in which a plurality of pump cylinders are arranged in a circle about the central axis of the pump and on the central axis and within the pump casing is placed a centrifugal unit which controls the supply of fuel to the engine cylinders. The casing I in which thel pump is contained is divided into sections for the easy assembly of the various parts and in the lower portion thereof is a cam base 2, rotatably mount- 5 ed on bearings 4 anddriven from the engine in any suitable or convenient manner. The cam base 2 is provided with a `cam 3 which operates the pump plungers (not shown) for forcing the fuel to the Aengine cylinders and also operates a l0 shaft 6 which drives a centrifugal unit 8. The shaft 6 is tubular and at its upper end is provided with openings to receive a pin I0 on which the arms I2 of the weights I4 are pivotally mounted. The weights I4 have semi-cylindrical inner faces 15 and,y when at rest, enclose the shaft 6; The upper ends of each ofthe weights I4 is rounded -to form an involute gear tooth surface as at I4 which bears against a cooperating surface I6 of a cross piece or member I6 the surface I6 being inclined to correspond to the tooth of a standard rack. The cross piece I6 is fixed to the upper end of a sleeve I8 slidably mounted in the tubular shaft 6. The sleeve I8 is provided adjacent its upper end with elongated openings- 25 I9 which permit of movement of the sleeve with respect to the pin I0 and at its lower end with an inwardly projecting annular shoulder 20 which serves as a seat for a spring 22. The spring 22 is confined under aninitial stress be- 30 tween the shoulder 20 and a plunger 24 slidably mounted in the sleeve I8 and bearing against the pin Il). f

Extending transversely of the shaft 8 -below the sleeve I8 is a sleeve 26 which is xed in the shaft 35 6 and serves as a housing for a spring 28, the opposite ends of the spring 28 being held in position to bear against the Weights I4 by pins 38 fixed in the weights I4. Secured in the upper end of the sleeve I8 is a plug or button I8 which 40 bears against the lower end of a valve 32 slidably mounted in a bushing 33 fixed in the bore of the casing I. Both the valve 32 and bushing 33 are provided with ports and passages cooperating with ports and passages in the casing I 45 and the pump plunger bushings in the control of the supply of fuel by` the pump to the engine cylinders. The 'upper end of the valve 32 is shaped to form a shoulder, as at 32', which serves as a seat for 50 ner edges seated on shoulders on spacers or separators 40, the whole forming a spring which acts upon the valve 32 in opposition to the thrust of the centrifugal unit v8. The action of the spring 34 may be adjusted by a tubular member or `sleeve 42 engaged with the upper separator 40 and' threaded into a bushing 43 slidably mounted in a housing 44 secured to the casing I. bushing 43 is provided with a rack (not sh'own) for adjustment by a manually operated shaft 46 having teeth 46' thereon which engage with the teeth of the rack. Secured in the valve 32 by a pin 48' which prevents rotation of the valve 32 with respect to the valve seat 33 is a valve stem 48 which has a. nut 50 threaded on its upper end to be engaged by the sleeve 42 when the bushing 43 is shifted to the limit of its movement upwardly. The stem 48 and nut 50 provide a means forpositively operating the valve 32 without the spring 34 serving as part of the operating means.

In a centrifugal unit constructed as shown in the drawing and operated with its shaft vertical, the center of gravity of each of the weights I4 lies to one side of both the axis about which the weights revolve and the vertical plane in which the weights are pivotally mounted on the pin I0. so that the bottoms of the weights I4 are drawn inwardly by gravity towards the shaft 6 and until the speed of the engine is such that the centrifugal force acting upon the weights overcomes the force of gravity on the weights, there is no energy for performing useful work in the operation of the control valve 32. This vprevents the operation of the centrifugal unit at speeds less than that which produces the necessary centrifugal force unless means be provided for compensating for the force of gravity and which tends to move the Weights outwardly from the shaft. In the drawing the transversely arranged spring 28 provides this compensating force and permits of use of the centrifugal unit for' speed control at speeds less than that at which the centrifugal force equals the force of gravity. Under certain conditions of operation the weights I4 tend to vibrate or flap atlow speeds and to prevent this and to maintain the weights in positive engagement with the member I6 the spring 28 is placed under greater stress than is necessary to compensate'for gravity and the spring 22 is provided to compensate for the excessive action of the spring 28 in order that the thrust of the cen. trifugal unit will not be rendered excessiveby the action of the spring 28,

When the centrifugal unit is arranged horizontally,unless the transverse spring 28 be provided, the vweights I4 tend to fall into contact with the shaft 6 as they pass over the shaft and to fall away from the shaft as they pass under the shaft at low speeds causing chattering of the weights. While one weightoffsets the effect of the other on the thrust of the plunger I8 the chattering is undesirable and is prevented by the spring 28. The spring 28, however, unbalances the centrifugal unit in the direction of the delivered thrust but this is compensated for by the spring 22. The degree of compensation in both the vertical and horizontal arrangements of the governor are determined by the stiifness and initial compression of the spring 22 and these factors may be varied to either just neutralize the spring 28 or over or under compensate therefor as desired.

In a simple centrifugal unit such as is shown in the drawing the effect of the weights increases proportionately to the square of the speed as well as in proportion to the distance from the axis The according to the logarithm of the spring reaction.

This relation, in the cases of a helical, compression, extension or torsion spring, is a straight line, the spring reaction varying directly with the compression, extension or twist of the spring. The same is also true of a simple or .compound beam of flat spring stock. However, a spring comprising 'a plurality of flat spring disks, arranged as shown in the drawing and deflected by cupping gives an essentially logarithmic relation betweens the spring deiiection and spring reaction which follows closely that required for precision control over a wide speed range by the centrifugal unit shown. thickness of the disks so that the greater the de- 'flection Aby cupping the greater the stiiness of the spring, i. e., the greater the change in reaction for a given additional change in deflection. By substituting disks of different thicknesses and varying the number of discs used a spring of the desired characteristics for a particular combination of centrifugal unit and valve may be secured. Thus, by increasing the thickness of the disks the extent of the deflection for any given thrust is lessened while by increasing the number of disks used the total deection for any given thrust is increased.

The arrangement of the centrifugal unit 8, valve 32 and spring 34 in the drawing is such that the thrust of the centrifugal unit and spring are transmitted directly and in the same straight line to the valve 32 so that frictional losses are avoided and only the friction of the valve has to be overcome. This permits of smaller and lightercentrifugal unit and spring and a corresponding decrease in the inertia of the parts and the tendency of the governor to hunt or make excessive adjustments of the Valve 32. The arrangement also permits ofthe parts being alined on the central axis of a pump of the construction described above so as to produce a compact unit. f

In operation, the engine speed maintained is determined by the pressure applied to the spring 34 by means of the shaft 46.and the sleeves 43 and 42. Operating the shaft 46 to increase the pressure on the spring 34 tends to shift the valve 32 to decrease the leakage of fuel at each pump stroke and increases the governed speed of the engine for a given load. Decreasing the pressure on the spring 34 permits the centrifugal unit to shift the valve 32 to increase the ,leakage at each pump stroke and reduce the governed speed of the engine for a given load. Continued operation of the shaft 46 in a direction -to decrease the pressure on the spring 34 shifts the sleeves 43 and 42 upwardly until the sleeve 42 engages with the nut 5U on the valve stem 48 and. thereafter the sleeve 42 shifts the valve 32 positively, by means of the nut 50 and valve stem 48, toa position in which the leakage at each pump stroke is sufficient to prevent any fuel-being supplied to the engine cylinders and the engine stops. During the operation of the valve 32 by the valve stem 48 the pressure exerted on the spring 34 by the sleeve 42 remains unchanged.

The cupping increases the effective.

I claim- 1. A centrifugal unit comprising a rotatable shaft, weights plvotally mounted on said shaft A and spring'means extending transversely through ed in said shaft and opposing operation' of saidv said shaft and aiding movement of said weightsv under centrifugal action.

2. A centrifugal unit comprising a rotatable shaft, weights pivotally mounted on said shaft, a sleeve extending transversely of said shaft and spring means in said sleeve and engaging said weights tov assist the centrifugal action of said weights.'

3. A centrifugal unit comprising a rotatable tubular-shaft, weights pivotally mounted on said shaft, spring means extending transversely ofv said shaft and tending to aid movement of said plunger by said weights.

5. A centrifugal unitcomprising a rotatabl tubular shaft, weights pivotally mounted on said shaft, spring means extending transversely of said shaft and tending to aid movement of said weights under centrifugal action, a plunger slid` ably mounted in said shaft, a cross-member carried by said plunger, said weights and said crossmember having cooperating gear-tooth surfaces, and a spring mounted in said shaft and opposing operation of said plunger .by said weights.

6. 'Ifhe combination with a centrifugal unit having centrifugally operated weight members, driving means for said weight members and a thrust member operated by said weight members of a spring comprising a plurality of spaced at disks of spring metal alined with said thrust -member and opposing operation thereof, said disks being cupped by the action of said centrifugal unit and having an effective spring stiffness which is varied by the action of said unit.

7. In a device of the class described, a centrif. ugal unit: having centrifugally operated weight members, driving means for said weighmembers and a thrust member operated by said weight members and a spring comprising a plurality o f flat spring metal rings and separators spacing pairs of said rings at their inner and outer edges alternately, `said spring being alined with said thrust member and opposing operation thereof. the rate of change in the reaction of said'spring increasing with the detection of said spring rings.

8. In a device of the class described, a centrifugal unit having centrifugally operated weight members, driving means for said weight members and a thrust member operated by said weight members, a valve axially alined with said centrifugal unit and operated by said thrust member and a spring -comprising a plurality of liat spring metal disks and alternately arranged inner and outer separators spacing pair 'of said disks, said spring being axially alined with said valve and opposing operation of said valve by said thrust member with a force whose rate of increase in` creases with the deflection of said disks.

9. The combination vwith av centrifugal unit having centrifugally 'operated weight members,

driving means for said weight members and aA thrust member operated by said weight members, of a cupped spring metal disk resiliently opposing the operationof said thrust member and means for adjusting the cupping of said disk to establish a predetermined initial-stiffness for said spring in opposing operation of saidthrust member.

10. 'I'he combination of arotatable weight movable outwardly from its axis. of rotation by cen, trifugal force and spring means opposing the outward movement of said weight, said spring means comprising a cupped disk member supported by a contacting memberl adjacent a periphery of said disk member in such'manner as to permit sliding movement of said disk member with respect to said contacting member with a change in the cupped condition of said disk member.

1.1. In a speed` controller, a rotatable weight member movable outwardly from its axis of rotation-by centrifugal force, spring means controlling said outward movement of said weight member,

and adjustment means' for varying the force of reaction of and lthe eiective spring stiffness of said spring means corresponding to a given out- Ward movement of said weight member to select the speed determined by the controller, said spring means comprising a disk spring the extent of the cupping of which is varied by movement of said weight member and by said adjustment means.

12. In combination a rotatable shaft member and a weight member rotated thereby, said weight member being movable outwardly from its axis of rotation by centrifugal force, spring means controlling the said outward movement of said weight member in response to centrifugal force and adjustment means for varying the effective spring stiffness of said spring means, said spring means comprising a cupped disk-type spring member and said adjustment means serving to change the degree of cupping of said spring member corresponding to a given .extent of said outwardv movement of said weight member.

WARNER T. TABB.

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