US2382849A

US2382849A - Cam

Info

Publication number: US2382849A
Application number: US437538A
Authority: US
Inventors: Gardell L Bennett; Dyer Frederick
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1942-04-03
Filing date: 1942-04-03
Publication date: 1945-08-14
Anticipated expiration: 1962-08-14

Description

Aug. 14, 194s.

` G. L.. BENNETT `:a1-A1. 2,382,849 y CAM Filed April 3, 1942 2 sheets-sheet 1 Inventors:

Gardell L. Bennett,

Frech-'ick Dger;

The@v Attgme,

Aug. 14, 1945.

G. L. BENNETT ET AL CAM I 2 Sheets-Sheet 2 Filed April C5', 1942 Inventors'. Garde" .l' Bennett,

F edrick D ern b5 fvg, Their` Attorng.

Patented Aug. 14, 1945 CAM Gardell L. Bennett and Fredrick ZDyer, Schenectady, N. Y., assignors'.toiGeneralfElectric Company, a corporation of New-York Application April .3, 1942,Serial`No. 437,538

(c1. m-.sesi

2 Claims.

Our invention relates tocam operating means, more particularly to cam operating means for electric switches, and has for its object simple, reliable and inexpensive shockproof cam operatingmeans.

.In the operation of electric switches, a single cam against which-a follower member is held by means of a spring has the disadvantage that it is ynot shockproof because of the fact that the spring is the operating means in one' direction. For shockproof construction, two opposed cam faces, i. e., a cam slot, is required but such cams are costly, especially Where a sequence of movements is required.

In carrying out our invention, we provide a plurality of cam sections having cam grooves in laterally different positions, `which sections are interchangeable and may be assembled in desired relations to give the desired shape of cam slot.

For the movement of a switch member between closed and open circuit positions, we provide four diiierent interchangeable cam sections, one for each position of the switch and one to effect movement of the switch in each direction.

More particularly, we provide oneor more rotatably mounted operating members, each consistingof a disk sector provided with an arcuate slot on one side, which slot has for its center the axis of rotation of the disk. In this slot we assemble the interchangeable cam sections thereby to form a cam slot on one side of the disk sector of such shape as to give the desired vsequence of operations.

Thus by suitably assembling thecam sections, the circuit controlling member can be operated from one position'to another at any desired angular position of the disk sector and maintained in either its closed or open circuit positionthroughout a predetermined amount of angular movement of the disk sector.

For a more complete understanding of our invention, reference should be had to the accompanying drawings-in which Fig. 1 is a side elevation view, partly in section, of an electric switch embodying our invention; Fig. 2 is a plan view, partly in section, of the device shown in Fig. 1; Fig. 3 is a partial sectional view along the line 3-3 of Fig. 2 looking in the direction of thearrows;` Fig. 4 is a detail planview showing the position ratchet means; Fig. 5 is a detail perspective viewof. an operating camdisk; whileFig. 6 isl an exploded view in perspective of the stop means for the rotatable element.

Referring to the drawings, in carrying'` cutour invention in one form weprovide asquare 'shaft Shaft.

lllhaving itsjjournal ends mounted inbearings l mounted'inpairs andthe sectors of each pair are Y directlyopposite eachother in acommon plane.

As shown inFi'g. 5, each sectoris provided with a square recess 2l Aat its center into which one side of theshaft HJ ts and with a transverse'fhole 22 which registers with a ,tapped hole 23 in the Thus the'two disk sectors of a `pair are placedon opposite sidesoffthe shaft l 0 Vwith their holes "22v registering withithe hole "23 after which eachis secured separately .to the shaft'by a screw (not shown) engaging thetappedhole 213.

The sectors l5 to `20, inclusive, are identical. in construction. 'Cooperating .with them are identi,- cal switch structures only three of which, 2'4, 25 and 1'2'6, are shown. Each switch structure comprises a contact arm'21 (Fig.` l)V having a stationary ,pivot'28 at itslowerend andcarrying'a bridging contact 29 atits upper end. These contact arms are'made of an electrically insulatingma- .terial, preferably a molded compound such as. phenolic eondensationproduct.

vEach contact farm isprovided with a follower member'shown as a roller'SUsecured to the contactarm on one side andhavingits aXisof rotation parallel withthe axisofthe pivot `28. This roller extends into a cam slot 3l, Fig. i5, in the side or faceof the disk sector adjacent the contact arm whereby, `when the handle is moved to turn'the shaft and'disk sector, the sides of the slot '3 l on opposite'sidesofthe'roller 30 cause the rollertomove radially with respect to'the shaft in conformity'withthe shape of the slot whereby the-contact-arrne j'is moved between its closed and'open circuitpositions.

' shownin Fig. 2,` the contact arms'21, -28 and '23 are :situated onlthe cam slot sides ofthe sector 20, f8 1and IIS, respectively, -with Vthe operating roller-30 of reach eont-actiarm extending into the is provided with a pin 38 on its inner side whichsiz. extends through a hole 39 in the disk sector. On

its outer end this pin is provided with a peripheral groove (not shown) forming a small shankV over which is slipped a forked spring retaining member or clip 40. This clip 4D when it is inserted in place is compressed against the side of the disk sector l thereby to hold the cam sections in place, and

the prongs of the clip 40 are separated somewhat' so that the clip is secured in place although it y maybe readily removed by a suitable tool, such as a screw driver.

Inkview of the fact that the switch arm 21 has only two positions, that is, a circuit closed position and a circuit open position, we have found that by providing four different cam sections 33, a cam slot 3| can be built up with the sections to give the desired movement of the contact arm at any desired angular position of the disk sector- `and maintain the contact arm in any desired position. Thus, referring to Fig. 5, it will be observed that four dierent sections are providedan open circuit positional section 33a, a transfer section 33h which moves the switch arm from the open tothe closed circuit position, an open circuit positional section 33o, and a transfer section 33d which moves the contact arm from the closed back tothe open position.

These four cam sections 33a to 33d have the same overall size and construction so that they are interchangeable and have the same width of cam slot. They differ, as shown in the drawings, in the position of the slot adjacent one side or the other of the groove 32, i. e., as shown, in a radial direction, the positional sections 33a and 33o having,` respectively, radially inner and outer slots, while the transfer sections 33h and 33d have radially or'obliquely extended slots arranged to'join the slots of the sections 33a and 33e for, respectively, radially outward orinward movement of the roller. Thus, the sections 33b and 33d are the ones that produce radial movement of the roller.

`Considering the particular cam slot assembly shown in Fig. 5, beginning at the upperend, i. e., the counterclockwise extremity of the slot 3|, it will be observed that the roller is in its radially innermost position and holds the switch arm in its open circuit position. As the disk sector is turned in a counterclockwise direction, the contact arm is moved by the third cam section to its closed circuit position where it is maintained over two cam sections. Then the contact arm is moved back to its open circuit position where it is maintained for four cam sections, after which it is moved to its closed circuit position, maintained there over one cam section, and then returned to its open circuit position over the next three remaining cam sections.

Preferably, the sectors to 20inclusive, and the cam sections 33 are die cast so that they do not require machining.

As shown in Fig. 1, the contact arm 21 is mounted on a metal supporting bracket 4| and. this bracket in turn is secured by a screw 42 to a cross supporting bar 43 secured to the bottom section I3 of the casing. The bracket 4| has a portion 44 extending upward above the cross bar 43 and to this portion is secured by a screw 45 a support 46 for the stationary contacts 41 and 48. This support 46 is also made of an electrically insulating material, preferably a molded material.

Thus, it will be observed that by removing the screw 42, the bracket 4| can be released from the cross bar 43 and each switch assembly removed as a unit. In order to secure the bracket 4| against turning about the screw 42, lugs 49 are provided on the lower end of each bracket which are in engagement with the cross bar when the screw is tightened.

In order to define the various angular positions of the shaft l0 for the desired switching positions, a metal disk sector 50, Figs. 2 and 4, is secured to the shaft with a separate sector 5| on the opposite sides of the shaft for indicating the open position only. These sectors 50 and 5| are secured to opposite sides of the shaft bymeans of separate screws, as shown. A spring pressed roller bears on the periphery of each of these sectors 50 and5 only one roller 52 (Fig. 2) bearing on the sector 5| being shown in the drawings. This roller is mounted on the upper end of an arm 53 (Fig. l) having a xed pivot 54 on the casing and biased in a counterclockwise direction, as seen/in Fig. 1, by a compression spring 55. An adjustable nut 56 is provided for the xed end of the spring and by adjusting the position of this nut on its supporting bolt 51 the force applied by the spring can be adjusted as'desired.

The two separate arm wheels 50 and 5| are provided in order that some particular position, suchas the open position, for all of the contact arms can be designated to the operator as he moves the handle. vThus the sector 5| is provided with a single depression 58 for its roller 52, a corresponding depression 59 being provided on the othersegment for its roller (not shown). When these two rollers are in these depressions, a much greater force is required on the part of the operator to turn the shaft and sectors to the next position in either direction. This increased holding force is an indication to him that the switch is in this particular position.

Furthermore, with the separate positioning rollers, the spring pressure of each can be adjusted independently. Preferably, the adjustment is such that a relatively light pressure is applied by the roller to the sector 50 whereas the roller applies a relatively great pressure to the sector 5|. `When the roller is out of the depression 58, however, it does not appreciably impede the rotation of the shaft because it bears on the remaining smooth arcuate surface ofthe sector 5|.

In the switch disclosed, six operating sectors and six contact arms are shown for a multiplicity of control steps, for example, in the starting and control of an electric motor. Obviously, any suitable number of sectors and contact arms can be used'to suit the requirements. l

An adjustable limit stop means is also providedV for limiting the arc through which vthe sectors can be iturned. In View of the fact that each sector is slightly less than in extent, the permissible rotationof the shaft IU must be limitedvto less 1than180" 'in any case. This is effected by stop projections 60 and 6| (Fig. 2) on the casing on opposite sides of thesh'afty I0 at `thehandle end. On the shaft adjacent the handle'are two

stop segment members

62 and 63 having projections 64 and 6,5 (Fig. 6) extending out far enough from the shaft to engage the stop 66 or 6I. These members are provided with holes 66 and 61 lthrough which a hub 61a on the handle extends loosely. Also, they are provided with arcuate series of adjustment holes 68 and 69 through some registering two of 'which the screw 16 extends and is seated in a threaded aperture 1| in the lower end of the handle.

It will be observed that for the greatest possible amount of movement of the shaft l0, .the two stop members 64 and 65 will be in registering relation. For a decreased amount of rotation, the members 62 and 63' are turned on the hub 61a with respect to each other so as to separate the projections 64 and 65 as desired, after which the screw 10 is inserted and the members clamped to the lower end of the handle.

The lower supporting pant of the casing vI3 is provided with an upper removable portion 12 carrying a gasket 13 to provide a sealed joint between the two.

While we have shown a particular embodiment of our invention, it will be understood, of course, that we do not wish to be limited thereto since many modications may be made, and we therefore contemplate by the appended claims to cover any such modications as fall within the true spirit and scope of our invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. The combination with an operating shaft of means for turning said shaft, a disc member secured to said shaft and rotatable with said shaft, said disc member being provided with an arcuate groove on one side near its periphery having for its center the axis of said shaft, a plurality of pairs of interlocking means on the walls of said groove, the interlocking means of each pair being oppositely disposed from each other in a radial direction with respect to said disc member, aI plurality of interchangeable cam sections mounted in said groove, each of said cam sections being provided with securing means at each end cooperating with one of a pair of said interlocking means whereby said cam sections are secured against movement along said groove, said cam sections having each substantially the same overall dimensions and being in side-by-side relation when mounted in said groove, each of said cam sections being provided with a cam slot having a predetermined radial width and said sections being arranged with said cam slots communicating with one another to form a continuous cam slot, there being sections having arcuate slots respectively adjacent their radially outer and inner ends and a cam section between said last mentioned sections having a connecting transfer cam slots extending obliquely with respect to the radius of said disc member passing through said transfer cam slot so as-to join together said arcuate cam slots, a movably mounted driven member, and a follower member on said driven member lying in said continuous cam slot whereby upon rotation of said disc member said driven member is moved radially by the walls of said transfer cam slot between inner and outer positions, said follower member being locked by the walls of said arcuate cam slots in each of its inner and outer positions against movement radially in each direction.

2. The combination with an operating shaft of means for .turning said shaft, a'disc member secured to said shaft and rotatable with said shaft, said disc member being provided with an arcuate groove on one side near its periphery having for its center the axis of said shaft, a' plurality of pairs of projections on the walls of said groove, the projections of each pair being oppositely disposed from each other in a radial direction with respect to said disc member, a plurality of interchangeable cam sections mounted in said groove, each of said cam sections being provided with a slot at each end whose walls embrace one of a pair of said projections whereby said cam sections are secured against movement along said groove, means securing said cam sections in said groove, said cam sections having each substantially the same overall dimensions and being in side-by-side relation when-mounted in said groove, each of said cam sections being provided with a cam slotl having a predetermined radial width and said sections being arranged with said cam slots communicating with one another ;to form a continuous cam slot, there being sections having arcuate slots respectively adjacent their radially outer and inner ends to form outer and inner arcuate cam slots having for their center the axis of said shaft and a cam section between said last mentioned sections having a connecting transfer cam slot extending obliquely with respect to the radius of said disc member passing through said transfer cam slot so as to join together said outer and inner cam slots, a movably mounted driven member, and a roller on said driven member lying in said continuous cam slot whereby upon rotation of said disc member said driven member is moved radially by the walls of said transfer cam slot between inner and outer positions, said roller being locked by the walls of said arcuate cam slots in each of its inner and outer positions against "H" movement radially in each direction.-

GARDELL L. BENNETT. FREDRICK DYER.