US2588159A - Centrifugal actuator - Google Patents

Description

March 4, 1952 c. s. PHILLIPS CENTRIFUGAL ACTUATOR 2 SHEETS-SHEET 1 Filed April 4, 1946 //J s svrae 614557-51? .5. Ph /LL12; 1 w HTTOEMEK March 4, 1952 c. s. PHILLIPS 2,588,159

CENTRIFUGAL ACTUATOR Filed April 4, 1946 2 SHEETSSHEET 2 //\//E 15/70 2: C1455 TE? 5. PH/LL/Pj,

5% JW w HTT PMs/s.

Patented Mar. 4, 1952 CENTRIFUGAL ACTUATOR Chester S. Phillips, St. Louis, Mo., assignor to The Emerson Electric Manufacturing Company, St. Louis, Mo., a corporation of Missouri Application April 4, 1946, Serial No. 659,452 6 Claims. (o1.2e4-15) of actuating device, having weights arranged to develop increasing mechanical advantage as they move outward, for actuating short-circuiting or brush-lifting mechanism, or the like. Stated differently, it is an object to provide a centrifugal actuator of this kind, wherein the actuating force increases continuously but at a greater rate than the increase of speed of rotation, so that the actuation may occur with a snapaction, and so that variations in operating resistance may be overcome without change in the desired result.

A further object of the invention is to provide a mechanism or this type affording snap-action to effect sure and rapid sh-ort-circuiting of the rotor windings, thus reducing pitting of the commutator bars, avoiding poor contact, and overcoming adverse effect of any variations in operating resistances in the mechanism. A particular object of the invention in this connection is to provide a plurality of centrifugal weights that are interlocked sothat there will be even operation, without rocking of parts into irregular positions.

A further object of the invention is to provide a mechanism of this type having reduced friction, whereby its action is sure and consistent and wear is reduced.

' A further object is to provide a mechanism of this kind having increased reserve force above the short-circuiting speed, whereby a more assured and consistent operation may be obtained.

A further object is to provide a device of this kind in which the connection between the device and the operated parts may be disposed parallel to the motor shaft. An especial object is to provide a centrifugal actuator having a member fixed to a shaft, a member axially movable along the shaft, and centrifugal means between them arranged to provide even movement of the movable member, so that connectors between the I movable member and the device to be actuated may be arranged close to and parallel with the shaft for endwise displacement.

In the drawings:

Fig. 1 is a transverse vertical section through a motor of this type, showing the mechanism in place;

Fig. 2 is an enlarged view of the right end of the parts shown in Fig. 1, with the mechanism of the present invention shown in side elevation there-on and with the weights in their inner position;

Fig. 3 is a fragmentary view similar to Fig. 2, but showing the weights in their extended position when the motor is operating at running speed;

Fig. 4 is a transverse view taken on the line 4-5 of Fig. 2;

Fig. 5 is a transverse view taken on the line 5-5 of Fig. 2; and

Fig. 6 is a transverse view looking in the opposite direction, and taken on the line E6 of Fig. 2.

The invention is not primarily concerned with the details of the design of the motor. In general, however, the motor is indicated at It, and comprises a base ll, upon which a cylindrical motor housing I2 is mounted. This motor housing has end Shields 13 and M secured to it in conventional fashion.

The motor housing [2 contains stator windings, generally indicated at I5. A rotor shaft 16 is supported in bearings in the end shields l3 and I4, and it, in turn, has rotor windings, generally indicated at H. These windings are supported upon the shaft 16.

One end of the rotor windings receives a flanged cup-shaped fan 2%. It interfits with the ends of the rotor windings, and fits against a ring 2i that snaps into a groove in the shaft I6. The rotor laminations and the fan 20 are clamped between the ring 2| and a disc 22 on their opposite ends. This disc 22 has a pressed fit onto the shaft l6 as part of a commutator assembly. The assembly includes a flanged cylinder 23 fitted over the disc. This cylinder has an inward flange engageable by the disc 22, for holding the cylinder in place.

The cylinder 23 has an internally threaded and outwardly displaced rim 24. An insulated, conductive, short-circuiting ring 25 is inserted into the cylinder 23, as shown. A plurality of commutator bars 26 are inserted, said bars being shaped as shown in Fig. 1, so as to have rearwardly extending dovetails that may engage in an annular groove formed by the cylinder 23, the short-circuiting ring 25, and a cut-away ring 21 that is threaded into the flange 24. The bars 26 are insulated from the ring 25 and from the other parts, as well as from each other,

member 6| that slides on the shaft l6.

as is known in the art. They are connected to the rotor windings in familiar fashion. It will be seen that they have projections extending radially inward, so as to provide inner edges 28 that are substantially coextensive with the inner surface of the ring 25. V

The brush mounting includes an inner tubular projection .36 extending inwardly from the center of the end shield l3. This has a cylindrical outer surface that receives a brush supporting yoke 3|. This yoke has bosses 32 on it, between which an arm 33 on a stabilizing ring 34 extends. The ring 34 is secured to the end shield, to hold the brush ring 3| against rotation except when adjustment is made, as by conventional means not shown and not a part of this invention. The brush ring, however, is permitted to slide axially on the cylindrical projection 31).

A suitable number of brush holders 3?, formed on the brush yoke ring 3|, support brushes 38 that are adapted to engage the commutator bars '26, and preferably are resiliently urged thereagainst to compensate for wear, in the accustomed way. 7 The mechanism to short-circuit the commutator segments and to displace the brushes from them includes a centrifugal device mounted at theopposite end of the motor. Referring partie- 1 ularly to Fig. 3, this device includes a fixed collar 45 that is secured, as by a pin, to the shaft it.

There is also an axially movable plate 46 that is spaced from the ring 45 by distances that are determined by the positions of eccentrically weighted linkages joining the two parts 45 and 46. p

The collar 45 has a plurality of bosses 48 that project radially outwardly along the inner edge of the collar. Three such bosses are here illustrated. A pair of links 49 and 49' are freely pivotedat corresponding ends on opposite sides of each of thebosses 48. Each of the pairs of links 49 and 49, at their other ends, is freely pivoted I to a T head 50 of a centrifugal arm The other posed with respect to the shaft, and'the links 49 are substantially parallel to the shaft. The weights swing out toward and to the position of Fig-3, in which they are limited by engaging the fan 20'." "In this movement, the linkage acts as a toggle mechanism that is stopped shortly before it reaches its dead center position. The outward movement of the weight arms displaces the ,plate 46 away from the fixed collar 45.

The plate has diametrically arranged depressions 56 therein. Into them the ends of a pair of push rods 51 and 58 fit. These rods slidably extend through suitable openings in the rotor to the'opposite ends, where theymay operate the short-circuiting and brush-lifting parts. It will be noted that these rods remain parallel to the axis ofthe shaft vl6 during their operation.

The short-circuiting device includes a barrel Somewhat inwardly from its left end, the barrel 66 has a flange BI, and at its right end a washer 62 that may be assembled as a part.of the barrel. The

4 washer projects radially beyond the barrel to provide a flange corresponding to the flange 6|. Between the flanges, the barrel supports a plurality of short-circuiting segments 63. There is at least one such segment per commutator bar. They are held together, and more or less loosely around the barrel 66, by a wire 64. The arrangement permits limited radial movement of the segments within the confines of the flange 6| and the washer 62, so that they may move outwardly far enough to make good contact with the shortcircuiting ring 25 and the surfaces 26 of the commutator bars. These parts are insulated from each other as is obviously required.

The barrel 60 has a socket recess in its left end, 'to receive a spring holding member 61. The spring holder has a flange that is spaced from the flange 6| of the barrel 66, by a predetermined distance. A coil spring 68 is under compression between the holder 6! and a retainer 69 held onto the shaft Hi. The spring presses the barreland the washer $2 the-right against the push rods, and,through the rods, yieldably pressesthe plate 46 to the right. i The previouslymentionedspace between the flange 6| on the barrel and the flangeon the spring holder receives inturned flangesll on the brush yoke 3|. .7 The flanges H are narrower thanthe space. r

Theweights53 may be integral with the arm 5| orseparate and. attached to it, asin Fig. 3, if it isintended to obtainsome desired operating characteristics by varying. the weights 53 alone.

' Operation As the motor starts, the brushes 38 are in contact with the commutator bars 26, and the motor will operate as a repulsion motor, giving starting torque When .the motor attains a predetermined speed, the centrifugal devicewill causethe commutator bars to be short-circuited and the brushes to be moved away from thecommutator.

It will be observed that the.coil spring-68 acts,

through the interposed parts, on the push rods 51 and 58., Thesepush rodsare diametricallydisposed, to applyjthis forcesymmetrically to the plate 46, so that this plate is urged to theright in Fig. 1. The weights are disposedsymmetrically around the ,plate46hand the collar .45. vAs shown there are three weights. Other, numbers maybe used, but it is important that the, weights le a nce so. t at th platelifi w ll b caused to move evenly, without a rocking action. It will furthermore be seen that all of theweights are connected together through the two ring members. This insures that the weights will all move together and apply even force all around the periphery of the plate 46. v Y

. The spring 68 is set to exert a predetermined force, pressing the plate 46 to the right and tending to confine the weights to the positions shown in Figs. 1 and 2, in which they are in their most inward position, and in contact with the outer surface of the collar 45. v

At some chosen speed, such as 1400 R. P. M., the weights may begin to move outwardly. At the start, the weights 53 have the minimum mechanical advantage, as may be determined from the leverages involved. At this critical speed, the centrifugal forces of the weights and associated parts will exactly counterbalance the force of the spring as applied to the plate 46.

As the speed of the motor increases over this critical value, the centrifugal forces will produce an axial component that exceeds the resistance of the spring, and the weights will swing outwardly, forcing the plate 46, the push rods, the barrel, and associated parts, to the left, and compressing the spring 68. The mechanical advantage of the centrifugal forces increases very rapidly as the weights continue to move, in response to increasing rotor speed, outwardly toward the position of Fig. 3. Consequently, the centrifugally produced axial component of force acting against the spring 68 increases rapidly, and at a rate greater than the rate of increase of the spring force caused by its compression. The result is a rapid, snap-action displacement of the barrel 6!] to the left that takes place shortly after the motor passes its critical speed aforesaid.

As the ring 63 rotates with the shaft IS, the short-circuiting segments 63 will swing outwardly and contact the inner surface of the collar 25. When the barrel 6!] is moved to the left, the leftward ends of the segments 63 are brought into contact with the bottom edges 28 of the commutator bars 26, which thereby will be shortcircuited through the ring 25.

Also, as the ring 60 is moved to the left in this manner, its flange 6| will, in due course, engage the inwardly extending flanges H on the brush yoke 31, and displace the same to the left, ultimately moving the brushes 38 from the commutator bars. This lifting of the brushes is caused to occur after the short-circuiting of the segments.

With certain typical sizes of the parts and weights thereof, the forces to push the rods 5'! and 58, including the effects of the centrifugal forces of the arm 5| and weight 53, and those of the links 46 and 49', at the critical changeover speed, may aggregate 3.62 units. When the links 49 have moved to a position 1.5 out of parallelism with the motor shaft, the total axial force will have increased to 4.78 units. When the links 49 and 49' have moved to a 5 relationship to the motor shaft, the total force will have reached 6.80 units; and, whenthe weights reach their extreme positions in which the angle between the links 49 and the shaft is 16.5", the total force axially will be in the amount of 20.12 units.

The typical spring values under these conditions may be 3.62 units of force for the spring in starting position, 3.76 units for the spring force in the second position, 3.89 units for the spring force in the third position, and 4.15 units for the spring force in the fully opened position.

These typical values show that the total axial force exerted on the collar 46 by the eccentric mechanism increases very much more rapidly than does the spring resistance. It is this factor that produces the snap-action mentioned.

This snap-action results in rapid short-circuiting, thus reducing the pitting of the commutator elements, and ultimately reducing the tendency toward increase in friction and poor contact between the segments 63 and the commutator bars 26.

Furthermore, the arrangement provides a large reserve of force in the centrifugal device that will overcome any obstructions or variations in resistance that may occur in the mechanism. That is to say, ample force is present in this device for all normal operating conditions.

What is claimed is:

1. In a, centrifugal actuator for use upon a shaft rotating about a predetermined axis; comprising a first axially movable member movable from a first to a second position along the shaft axis,

a second member engageable onto the shaft; a

pair of links pivoted together at their inner ends, one link being pivoted at its outer end to the first member and the other link being pivoted at its outer end to the second member, weight means one of the links; the weight means being mov a l e outwardly from an inner or starting position to an outer or running position, by centrifugal force, and thereby separating the two members aforesaid by moving the movable member from its first to its second position; means limiting the return movement of the parts to first position to one wherein the two links are at an acute angle to each other, the weight means being disposed on its link, when said link is in first position, at least substantially as close to the axis of rotation as is the outer pivot of its link, and the lengths of the links being slightly less than the distance between their outer end pivots when the movable member is in its second position, whereby when the movable member is so disposed the links are substantially 18o apart but their lengths preventing them from moving over center, the llllAS thereby providing a toggle mechanism in which the mechanical advantage or the linkage in production of axial movement or the nrst member constantly increases as the Wfilgllu means him/6S (Jul).

2. 1.116 combination 01 claim 1, in which the wei ht means ro ec-ts laterally Ll'UIfl the link between the pivots thereof.

3. The combination 01 claim 1, in which the first of said links, in initial position, is substantiany per endlcular to the axis of rotation, and the second is substantially parallel to the axis; and in which Lllb wei ht means includes an arm pro ecting laterally from the first link, between its pivots and alongside the second link, w th a weight at the end or the arm.

4. The combination or claim 3, in which the means to limit return movement of the parts comprises a stop engageable by the weight to delimit inward movement of the weight.

5. The combination of claim 3, in which the arm is longer than the second link, and the weight comprises a head on the arm disposed beyond the end of the second link when the parts are in initial position.

6. The combination of claim 1, in which there is a spring urging the axially movable member toward the second member, and in which the weight means swing out by centrifugal force, and compress the spring, and in which there is a stop means to prevent the weight means from moving out to dispose the links at more than apart.

CHESTER S. PHILLIPS.

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

UNITED STATES PATENTS Number Name Date 958,159 Nelson May 17, 1910 1,088,576 Herr Feb. 24, 1914 1,214,286 Douglas Jan. 30, 1917 1,214,980 Weichsel Feb. 6, 1917 1,246,319 Purdy Nov. 13, 1917 1,479,519 Steiner Jan. 1, 1924 1,761,552 Whelan June 3, 1930 2,146,070 Holt Feb. 7, 1939 FOREIGN PATENTS Number Country Date 254,370 Great Britain June 30, 1926 865 France July 6, 1865

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