US2392266A - Method of making weights for centrifugal governors - Google Patents

Description

Jan. 1, 1946. H. R. RICARDO 2,392,266

METHOD OF MAKING WEIGHTS FOR CENTRIFUGAL GOVERNORS Original Filed Feb. 23, 1945 2 Sheets-Sheet 1 nvenlor Attorney Jan. 1, 1946. HR. RICARDO 2,392,256

I METHOD. OF MAKING WEIGHTS FOR CENTRIFUGAL GOVERNORS Original Filed Feb. 2:5, 194s 2 Sheets-Sheet 2 I Attorney Patented Jan. 1, 1946 METHOD OF MAKING WEIGHTS FOR CENTRIFUGAL GOVERNORS Harry Ralph Ricardo, London, England Original application February 23, 1943, Serial No. 476,870. Divided and this application Decem ber 26, 1944, Serial No. 569,886. In Great Britain September 17,1941

2 Claims. ('01. 29-148) so that complete dynamic balance may exist in -10 all attitudes of the governor. A further object is to produce a governor which for a given overall diameter shall have a maximum of active centrifugal weight.

. This application is a division of applicants col5 pending application Serial Number 476,870, filed February 23, 1943.

. According to this invention the weights of the governor are constituted by a series of similar segments formed by making radial cuts through 20 a body which has been shaped by turning. In the method employed for making these weights a body is turned with a substantiallycylindrical part and an inturned end and. the whole of this body is divided into equal segments by radial '25 cuts each of these segments constituting a weight and all these segments being used in the one gov ernor and being equally and simultaneously operative on a single spring-loaded part of the governor. turns is a knife edge formed by a part of an annular rib projecting on the exterior of the turned body which is cut into the segments which make the individual weights. When the governor is at The fulcrum about which each weight 39 rest the weights are nested all around the gov- 5 ernor spindle as an annulus each separate weight being a segment of the turned body and the fulcrum of each weight being an external projection forming a knife edge which bears on an annular surface on a rotating part of the governor, all the 0 weights being equally and simultaneously operative on one and the same spring-loaded part. In the construction there is combined with a cupshaped member mounted on and rotatablewith the governor spindle, a part acted on by a spring 45 against the pressure of which this part can be moved relatively to the spindle, and a series of similar weights constituted by all the segments into which an annular turned body has been divided by spaced radial cuts, every weight having 50 a knife-edge fulcrum about which it turns on a common annular surface formed within the cup-shaped member, while a part of every segmental weight bears against and as it moves acts on an annular surface on thespring-loaded mem- 5 ber. Sincethe weights merely bear and move on the two surfaces with which they are in contact, namely on the one hand the annular ledge on which the knife edges rest and turn and on the other hand the spring-loaded surface, it will be apparent that there is no positive connection or circumferential abutment between the driving spindle and the weights. Thus the drive is transmitted frictionally through these contacts which are made respectively at the fulcrum and the toe of each weight and the weights are consequently freeto move circumferentially with respect to the driving spindle when rapid changes occur in the driving speed.

The accompanying drawingsillustrate by way of example a construction according to this invention. In these drawings,

Figure 1 is a longitudinal sectional elevation of the improved centrifugal governor.

Figure 2jis a transverse section on the line 2 2 in Figure 1 looking in the direction of the arrows. Figure 3 is a projected view ofon of the weights as looked at from apoint on the axis of the governor situated towards the right-hand side of Figurel. 1

Figure 4 shows in elevation and on a much enlarged scale one of the weights and in section the annular ledge on which rests and turns the fulcrum of the weight. 1 Y

Within a stationary casing A the governor spindle B is mounted in bearings C" and is driven in such a manner as may be convenient by the engine or other mechanism which is to be controlled by the governor. On the spindle B, which is hollow, is fixed a cup-shaped member which may be described as having two parts of which one D is a cupped end portion, the inner part of which is connected to the spindle, and a cylindrical portion D suitably attached at D to the margin of the cupped part. This whole cup-shaped member D, D rotates within and clear of the outer casing and encloses the weights. By making this cup-shaped member in two parts it is possible for the end portion D to be made of a material capable of being hardened after machining. Within this part D and near its periphery there is turned a shoulder or ledge D? on which rest the knife edges of the fulcra of all the weights. These weights are made by radial cuts E (see Figure 2) through an annular body which has been shaped by turning'so that ithas a part F which is substantially cylindrical within as at F has a convenient formation externally with a single projecting rib G, and at one end has an inturned part H. 7 Each individual weight, which has the appearance of a longitudinal section through one side of the whole turned body,'has somewhat the shape of the letter J, as can be seen in Figures 1 and l, but with a projection, formed by the annular external rib G on the turned body, constituting a knife edge fulcrum Ci situated at about the:- commencement of the; curve of the JE, while the straight part of that letter constitutes the operative weighted portion F and the toe,

which is at the end of the curved part H...is. adapted to act on the spring-loaded partioifi the governor. It is important that aseach' weight swings aboutv its fulcrum the toe of the part. H shall tend to roll rather than, slide. on the face of the spring-loaded hardened washer K. To attain this it is necessary to determine the relative positions of the planes, normal to the axis of the governor, in which lie respectively the jfulcra of all the weights and the points of con-- tactbetween the. toes of the. weights and the washer K. The. arrangementin the. example illustrated issuch that at. or about the mid-point of the outward swinging movementv ofthe. weights from: their inmost or static position the plane. in which lie thetoe contacts will approximately coincide. with the. plane in which lie. the fulcra G of the weights.

The hardened washer K on which bear the toes of the parts H of the weights, is carried by a two-part sleeve adapted to sl de on the. governor spindle B. One portion L of this sleeve fits within the other part L and in the. spindle is a slot B which extends diametrically across and through it so as to allow a, key M topass across the axisof the spindle B and. slide within the latter. The ends of this key M are engaged by the two concentric parts: L. L of the. sl ding sleeve. lies a rod the one end. of. which rests. against this key M. Conveniently this rod is built up of two coaxial portions N, N which are separated by a ball, the arrangement serving to prevent the rodfrom binding owing to poss bledistortions of the hollow governor spindle. The arrangement is such that as the two-part sleeve L, 'L is caused to slide on the spindle B by the centrifugal action of the. Weights F the key M which passes through the spindle will caus the L formed on the one outer part L of the sliding sleeve. and between the last coil of the spring and this flange is a gimbal or rocking washer Q which provides a universal bearing for the end of the spring. At its other end the sprin P is engaged by a collar R which is loosely carried on a sleeve S screwed on to the governor spindle B this sleeve having an external flange S between which and an inturned flange R of the collar R is a gimbal or rocking washer T. The initial compression of the spring is given by screwing the sleeve S on to the governor spindle B.

It will be seen that when the spindle B is rotated beyond a certain speed the. centrifugal force acting on the ring of weights F will cause imparts movement to the control mechanism of Within the hollow governor spindle B- asoazoc th engine or machine with which the governor is associated. When the speed of rotation reaches a certain value the weights F turn about their knife-edges G until they rest against the inside 5 of the cylindrical portion D of the cup-shaped member which thus prevents. any further movement of the weights an o tw rd. direction- It will be understood that when the governor is at rest the spring P tilts all the Weights inwards and causes the centre of gravity of the weights to approach the axis of the governor until the sidesof the nested weights come into contact with oneanother'.

'By employing the method of manufacturing these weights; in accordance with the present invention all the weights of a particular governor will be identical. In this method of manufacture there is first formed by turning operations a. hollow cylindrical body with an inturned end portion. .This body is so shaped in the. prQcesS of turning that a. section throughit in a plane containing its, axis of symmetry will" be identical with the. contour of ach and all of the finished governor weights. The bodyis then divided into equal segments by two successive milling operations under they control of a dividing headstock. In one method of carrying out these milling, operations the turned partly cylindrical body is held on a suitably formed stump carried by the dividing headstock and the body is divided into segments .by means of th thin milling cutter. The extent of the cuts in this, Operation is limited to dividing the cylindrical part of the body into segments leaving the inturned end portion 35 untouched. Next a clamping ring is placed over the divided portion of the body and the inturned part. is divided at the same indexing positions ,as before, but using a thicker milling cutter. The effect of the second milling operation is to com,-

40 plete the division of the body into segments and arms 1-]? of which the toes bear on the washer K and through it on the part L, L on which acts the governor spring P. It is to be noted that the turned body is formed with a somewhat larger diameter than the actual diameter ofthe annulus formed by the segments when nested together. since when the bodyi's divided into these segments owing to th material removed by the radial milling cuts, the segments approach the governor axis when their side faces are in contact.

As each segment is cut from the body it has on wh'at may be called its back a portion G of the projecting rib which is provided by th turning operations on the body. At first thi rib extends all across the width of a segment, but by a milling operation the centre portion of. this rib is, removed as at. G. (see Figure 3) soas to leave two projecting partsG adjacent to the side edges of the segment these parts forming a pair of knife-edges on which the weight can turn. v These projecting parts G are then' hardened as also are the rounded ends of the inwardly projecting parts or toes I-Iv of the weights. The annular ledge D on which the knife-edges rest is also hardened. The cutting away of the intermediate portion of the rib on the back of each. segment may. be carried out while the body is in the milling machine under the control of the indexing head and before the division of the body into segments. If there iii) should happen to be slight discrepancies in the amount of material between each pair of knifeedges G these discrepancies will have very little effect on the position of the centre of gravity of the weight.

In Figure 4 there is shown on a much enlarged scale one of the weights so that there may be seen clearly its detail formation and the relative positioning of its parts. In the first place it may be noted that the fulcrum G constituted by the apex of the rib G is rounded and rests in the angle D of the ledge or shoulder D 'formed in the part D. This part D is given a curvature the radius of which is larger than the radius of curvature of the fulcrum G This ensures free roll- With respect to the position of the toe H of the part H in relation to the fulcrum, Figure 4 shows the weight in its inmost and static position and in :this position the plane XX, which is normal to the axis of the governor and contains the point of contact between the toe H and the spring-loaded washer K, lies appreciably to one side of the plane YY, also normal to the governor axis, in which lies the fulcrum G The distance between these planes XX and Y-Y is such that at or about the mid-point of the range of movement of the weight F the plane XX will substantially coincide with the plane Y-Y. This ensures a reduction in the amount of sliding between the toe H and the face of the hardened washer K in the middle part of the distance through which the weight can move, and it is preferably arranged that this shall be the condition existent at the normal speed at which the governor is used.

As the weights only rest within the restraining cup-shaped member D and have no positive connection with it and there is no circumferential abutment against which the weights can bear, it will be apparent that the drive is transmitted by the frictional load on the fulcra G and on the toes H Under all normal accelerations and decelerations this friction is suflicient to avoid any slipping of the weights relatively to the parts which are positively driven, but if the governor is subjected to violent or rapid speed changes, as for instance if the engine 'is passing through a period of torsional vibration, then the weights can slip round in the cup member D. In this way the driving shaft of the governor and any accompanying gearing will be relieved of heavy inertia loading. If the governor is fitted to an engine having a pronounced cyclic speed variation, the weights may creep round possibly first l5 ing of the fulcrum on the part on which it rests.

one way and then the other in the cup member D, and if thi action takes place it will tend to have a beneficial effect in distributing wear on the ledge D on which the fulcra rest.

It will be apparent that by employing this method for the production of the weights it is possible to ensure that they will all be identical not only as regards mass, but also as to the geometrical relation of the centre of gravity, the fulcrum point, and the point of application of the spring force. As a consequence of this complete identity between the weights a governor constructed as above described may be run at high speeds with complete freedom from vibration. Further, owing to the nature of the weight construction a large amount of active mass can be provided for the governor in a given space.

The detail shape of the weights, that is to say the initial shape given in the turning process to the body from which the weights are formed may vary.

What I claim as my invention and desire to secure by Letters Patent is:

1. In a method of forming weights for use in a dynamically balanced, centrifugal governor, the steps which include forming an annular body by turning to a shape such that a radial section copforms substantially to a side elevation of a weight suitable for use asa centrifugal mass in a governor, and cutting the body on a plurality of radial planes having uniform angular disposition about the body to provide a plurality of precisely similarly shaped segments, and machining an inter- 'media,-te part of the peripheral portion of each segment to form a recess having at the sides thereof circumferentially spaced projections to serve as fulcrums for the weight.

2. In a method of forming weights for use in a dynamically balanced, centrifugal governor, the steps which include forming an annular body by turning to a shape such that a radial section conforms substantially to a side elevation of a weight suitable for use as a centrifugal mass in a governor, and severing the body on a plurality of radial planes having uniform angular disposition about the body to provide a plurality of precisely similarly shaped segments, the severing being effected by cutting a portion of the body nearer the axis with a cut of greater width and by cutting that portion of the body remote from the axis with a cut of less width, whereby increased spacing is aiforded between the inner portions of adjacent weights when assembled.

HARRY RALPH RICARDO.

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