US2778897A - Generator output reversing switch - Google Patents

Description

Jan., 22, i957 H. J. WIEDEN GENERATOR OUTPUT REVERSING SWITCH Filed March 7, 1955 GENERATOR OUTPUT REVERSNG SWITCH Applikation March 7, 1955, Serial No. 492,727

15 Claims. (Cl. 206m-61.39)

This invention relates to improved reversing switches, for reversing the output circuit or circuits from a generator in response to reversals in the direction of rotation of the generator rotor.

There are various situations in which it is desirable to employ a generator adapted to be driven in either of two opposite rotary directions, and yet which will produce the same type and direction of current in an output circuit under both operating conditions. For instance, it is desirable in railroad cars to employ generators which will operate when the car is going either forwardly or in a reverse direction. The general object of the present invention is to provide an improved reversing switch for automatically reversing the generator output in such a situation. Preferably, the switch is capable of functioning in conjunction with a three phase alternator, to reverse the phase relationship between the three output lines upon a change in direction of operation of the al* ternator.

A switch embodying the invention includes two sets of contacts one ot which is rotatably shiftable relative to the other between different predetermined positions. Such rotary shifting of one set of contacts is effected automatically when the direction of generator operation is reversed. The shitting may be eiiected by means of an actuating assembly, including a pawl or pawls which act to engage shoulders associated with the movable contacts to turn them as the direction of generator rotation is reversed. These pawls may be automatically released by a suitable camming part when a shifting movement is completed, and during subsequent operation vof the generator the pawls may be centritugally held in entirely inactive positions.

A particular feature of the invention resides in the provision of means for protecting the contacts against excessive wear or rubbing during the rotary shifting movement of the movable contacts. Specically, l provide means acting to retract one set of contacts, preferably the rotating ones, axially away from the other set of contacts during the rotary shifting movement. Such retraction may be eiiected by cam means acting to cam the movable contacts axially away from the other contacts as a result of and during their rotary movement.

rlie rotating contacts may be carried by a rotatably shiftable carrier member or plate, and may be mounted for limited and spring resisted movement relative to that carrier. T he carrier may be bodily displaceable axially by the cam means, and may be yieldingly urged toward the stationary contacts by a suitable spring. Preferably, the stationary contacts are mounted to a stationary plate or member which is mounted opposite and in spaced relation to an end of the generator shaft. ri`he rotating contact carrier is then positioned axially between the stationary plate and the shaft end, with the pawl type actuating unit typically being attached directly to the shaft.

The above and other features and objects of the present invention will be better understood from the follow- States Patent f* 2,778,897 Patented Jan. 22,

ICC

ing detailed description of the typical embodiment illustrated in the accompanying drawing in which:

Fig. 1 is an axial section through an alternator output reversing switch constructed in accordance with the invention;

Fig. 2 is a view taken along line 2-2 of Fig. l;

Fig. 3 is a transverse section taken along line 3-3 of Fig. l;

Fig. 4 is a fragmentary view taken along line 4 4 of Fig. 1; and

Fig. 5 is a fragmentary sectional View similar to Fig. l, but showing the switch assembly during a shifting movement.

In the drawings, I have fragmentarily represented at 1t) a three phase alternator, having the usual outer housing 11, from an end of which there projects the alternator shaft 12. Shaft 12 is of course mounted for rotation within housing 11, as by means of a pair of ball bearings 13 (only one shown). The alternating current generated by the alternator 1t) flows from the alternator windings through three lines 14, 15 and 16 to a reversing switch generally indicated at 17, and leaves that switch through three output lines 18, 19 and 20. The alternator i@ is adapted to be rotatively driven in either of two opposite rotary directions, and the purpose of switch assembly 17 is to reverse the connections between alternator output lines 14, 15 and 16 and lines 18, 19 and 2t) when the direction of rotation is reversed, to thus always maintain the same phase relation between the currents flowing within lines 13, 19 and 20.

The reversing switch assembly 17 includes a main mounting plate 21 attached, as by screws 22, to alternator housing 11. The various parts of reversing switch 17 are carried by plate 21, and may be protected by enclosure within a switch housing 23, typically secured to plate 21 by screws 22. The stationary contacts of the switch assembly are carried by a plate 24, and the movable contacts are carried by a plate 25 which is rotatable relative to plate 24 and the stationary contacts through 18() degrees. The rotary plate 25 is shiftable relative to stationary plate 24 by means of a pair of spring urged pawls 26, which are carried by a mounting bracket 27 attached to the end of alternator shaft 12.

The stationary plate 24 is preferably formed of a suitable electrically insulative material, such as a suitable rigid plastic material, and extends directly transversely of the axis a of the alternator shaft. Plate 24 is mounted in spaced parallel relation to plate 21, at a location opposite the end of shaft 12, by a number of parallel mounting screws 28 rigidly attached at rst ends 29 to plate 21, and projecting outwardly therefrom. Elongated tubular spacing sleeves 3i? may be provided about screws 28, to space plate 24 from plate 21. Nuts 31 at the outer ends of screws 28 retain plate 24 in its illustrated mounted position on the screws.

Plate 24- carries five electrical contacts which are engaged by the movable contacts carried by movable plate 25. These stationary contacts on plate 24 include a first set of three contacts 32, 33 and 34 and a second and essentially diametrically opposite set of two contacts 35 and 35. Each of the tive contacts 32 through 36 comprises a screw like member yhaving a threaded stem 37 extending through plate `24 and having an enlarged diameter head 33 which is contained within a counterbore iu 'the surface of plate 24. The contact face 39 of each element 37 preferably is iiush with the inner surface of plate 2li. Each of the contact elements is retained to plate 24 by a nut 4t) at the `outer side of the plate, with the various leads being attached to the outer threaded portions of the contacts, and being retained thereto by additional nuts 41. An additional terminal 42, constructed the same as the various stationary contacts 32 through 36, is attached `to'plate 24 at a location such 4that itis never engaged by any of the movable contacts `carried by plate 25. This 'terminal 42 is utilized merely for connecting together two of the lead lines, which need not -be-reversed whenshaft 12 is actuated. For instance, 4lines 16 and yZtl may both be attached to 4terminal 42, so that the current-from line-16 always leaves the `switch mechanism through line 20 regardless vof the position of movable contact plate 25.

The other twolines y14 and 15 fromt'he alternator are connectedto stationary contacts 32 and 33, respectively. A jumper line 43 electrically connects contact 34 to con- 'tact 33 and thus to line 15. The output lines 18 and A19 are connected to stationary contacts 35 and 36.

The movable contact carrying plateiscircular, and

plates extends transversely of axis a, ,is essentially circularvand is formed of an electrically conductive material, typically steel.

Parts 25 and 44 are mounted for rota-ry movement about a shaft 45, which is stationarily attached to and projects inwardly from plate v24. Shaft 45 is axially aligned with shaft 12 of the alternator. 'Plate 44 has a 'central opening 49 with a diameter corresponding essentially to the diameter of shaft 45, to mount plates 25 and 44 for -the desired lr-otary movement, aswell as for limited axial movement along shaft 45. Plates 25 yand 44 a-re yieldingly urged axially toward plate 24 by a coil spring 47 disposed about shaft 45 and bearing at opposite ends against a shaft carried washer 46 and plate 44. The inner opening 48 in plate 25 may be considerably larger in diameter than opening 49 in plate 44, to pass spring 47 through plate 25 and into engagement with plate `44. v

Movable plate 25 carries six contacts, including a first set of three contacts designated numbers 5.0, 51 and 52, anda second vset of diametrically opposed contacts 53, 54 and 55. Each of these contacts50 throughSS comprises an elongated member having a shaft portion 56 extending through and axially movable .within a guiding portion 57 in plate At its end next. to plate 24, each yof the ce tacts 5. through 55 has van enlarged diameter head '58; for engaging `one of the .stationary contacts 3.2 through `36V to closefan electrical circuit. -Coil springs 59 yieldingly urge the movable .contactsaxially toward plate 24 and relative to plates 25 and 44. Head 60 at the other ends of the movable contacts limit suc'h axial movement reltaive to plates 25 yand 44, and serve as terminals to which threejumper lines 61, 62 and 63 between the various movable contacts are connected.

A first of the jumper lines 6.1 electrically connects contacts 5t) and 53. A second jumper line .62 interconnects contacts 51 Vand 55, while the third line 63 connects together contacts 52 land54. Inoue of its 'two rotary positions, the three movablecontacts 50, 51 and 52 engage stationary contacts 32., 33. and 34, while movable contacts 53 and .54 engage stationary contacts 35 and 36. In a second rotary position, offset 189 degrees from the iirst, movable contacts 53, 54 and 55 .engage stationary contacts 34, 333 and 32, respectively; while movable contacts 51and52 engage stationary contacts 36 and 35 respectively.

The movable contacts and their carrying d-isc 25 are adapted to be yieldingly retained in either of the two above mentioned rotary positions relative to plate 24 by means of a earn element 64. This cam element also serves the function .of axially shifting or retracting the movable contact str-uctureaway from the stationary contact plate 24 during rotary shifting of the movable conby a member of reduced dimension tabs or lingers 68 n extending through openings in plate 24 and turned at rtheir outer ends 67.

Axially opposite -the cam plate `or element 64, plate 44 has two parallel elongated portions thereof deformed axially toward plate 64 and to essentially V-shaped sectional coniiigurations corresponding to the detent recess or cam surfaces 65 of element 64. As will be understood, portions 66 of pla-te 44 are urged axially into the detent recess of plate `64 by spring 47, to thus yieldingly retain plates 25and 44 in either of two rotary positions odset circular degrees. Also, when plates 25 and 44 are turned by the mechanism later to be described, the engagement of V-shaped element 66 with cam surfaces 64 acts to cam plates 25 and `44 and the carried movable contacts axially away from plate 24, so that the movable contacts are out of engagement with plate 24 and the stationary contacts cari-red thereby during `the turning movement.

'The part 27, for rotatably shifting the movable contacts between their two positions, is formed of sheet material deformed to the illustrated Ll-shaped or channel shaped configuration. At a central location, element 27 is permanently and rigidly attached to the end of shaft l2, as by a bolt 69 screwed into the end of the shaft. Element 27 extends in opposite transverse directions from shaft l2, and carries at two diametrically opposite locations a pair of pawls 26, which are pivotally mounted to element 27 by a pair of pins 76 extending between the opposite side portions of channel shaped member 27. Pawls 26 have portions 26a projecting essentially axially topositions along the outside of plates 24 and 44, for rotatively shifting these plates in response to a reversal in the direction of rotation of shaft i2. Portions 26a of pawls26 are adapted to be centrifugally urged radially outwardly out of engagement with plates 25 and 44 when shaft l2 turns at a substantial speed. These portions 26a of the pawls are yieldingly Vurged radially inwardly into engagement with lplate 44, when the alternator is not turning at a substantial rate of speed, by a pair of springs 71 disposed about pins 70 and having their opposite ends bearing against pawls 26 and a pair of transverse pins 72 carried by element 27. Pins 72 also act tolirnit the radially outward movement of pawls 26 by centrifugal force.

Portions 26a of pawls 26 act to engage a pair of radially extending shoulders 73 and 74 formed on plate 44 at substantially diametrically opposite locations. These shoulders 73 and 74 extend radially between a reduced diameter portion 75 of plate 44 (of a diameter substantially equal to plate 25) and an enlarged diameter portion 76 of plate 44.

When shaft 12 and the carried pawls 26 are turning in one rotary direction, one of these pawls will engage shoulder 73 to turn plates 25 and 44 and the carried contacts in a first rotary direction. When the direction of shaft rotation is reversed, one of the pawls engages shoulder 74 to turn plates 25 and 44 and the carried contacts in the reverse rotary direction. In either case, this rotation of the discs 25 and 44 and the contacts continues until the engaged shoulder 73 or 74 reaches a bottom position (the position of shoulder 74 in Fig. 3) at which position the pawl which has been doing the turning is cammed radially outwardly by a pawl release cam 77, so that the pawl may then continue to turn without inducing further rotation of the movable contact strucarrasar ture. This release cam 77 may be ot' the substantially V-shaped conguration shown, presenting two oppositely disposed outer cam surfaces 78 and 79 which each extend radially outwardly as they extend circularly about the axis u, to thus effect the desired radially outward deliection of pawls 26 when turning in either direction. As will be apparent from the drawings, shoulders 73 and 74 are offset slightly from true diametrically opposite positions, in order to allow for the width of the engaging pawls 26. Cam plate '77 may be attached to stationary plate 24 by a pair of tabs Si) extending from element 77 through openings in plate 24, with these tabs being turned at the outer side of plate 24.

To now describe the operation of the illustrated reversing switch, assume that the rotor of alternator 10, and therefore shaft 12, are turning in a first rotary direction in which shoulder 73 of plate 44 is in its upper position, and shoulder 74 is in the lower position adjacent pawl release cam 77. in this condition, the reversing switch places line 14 in contact with line 1S through engagement of movable contact St) with stationary contact 32, and engagement of movable contact 53 with stationary contact 35. The connection between movable contacts 50 and S3 to complete this circuit is of course formed by jumper line 6l. Similarly, a circuit is closed from line ILS to line i9 through jumper line 43, contacts 34 and 52, jumper line 63, and contacts 54 and 36. The third line 16 from the alternator is of course connected directly to output line 20.

if the direction of rotation of the alternator and its shaft l2 is then reversed, the portion 26a of one of the pawls 26 will move into engagement with upper transverse shoulder 73 of plate 44, and as the shaft and pawl turn, will correspondingly turn plate 44 and the attached plate 25' and movable contacts 5t) through 55 through approximately i8() degrees. Such turning of the movable contact structure will continue until shoulder 73 moves to a lowermost position adjacent pawl release cam 77, at which position cam 7'7" will deiiect the pawl radially outwardly out of engagement with shoulder i3, so that the shaft l2 may continue to turn without further movement of the rotary contact structure. The speed of rotation will of course remain slow enough during the rst one-half turn to assure against centrifugal actuation of pawl 26 out of engagement with shoulder 73 before the latter has been turned through 180 degrees. Subsequently, of course, the speed will increase to a condition in which the pawls are centrifugally actuated radially outwardly, so that they do not contact plate 44 or cam 77 as they turn. lf the direction of rotation is again reversed, one of the pawls will engage the shoulder 74 which has now been actuated to an uppermost position, and will turn the rotary contact structure through approximately 180 degrees, at which position the pawl will be dellected radially outwardly by carn element 77, and the rotation of plate 44 will then cease. in the position in which shoulder 73 is adjacent pawl release cam 77, the electrical circuits are closed through switch 17 as follows. Line 14 from the alternator is connected to line 19 through contacts 32 and 55, jumper line 62, and contacts 51 and 36. Also, line 1.5 is placed in communication with line i8 through contacts 33 and 54, jumper line 63, and contacts 52 and 35. Thus, the connections from lines 14 and to lines L3 and 19 are reversed from their previous condition, to maintain the output in lines 13, 19 and 20 in the same phase relationship as before the shifting movement of the rotary Contact structure, even though the direction of rotation of shaft 12 has been reversed.

As plate dfi is turned through 180 degrees between its two circuit closing positions, the engagement of elements 66 with cam surfaces 65 acts to shift or cam the movable contact assembly 25, 4d, 50, 51, 52, 53, S4 and 55, axially away from plate 24, so that the movable contacts 50 through 55 do not engage plate 24 and the carried stationary contacts during the major portion of the rotary movement of the movable contacts. Preferably, the proportioning of the various parts is such that the movable contacts 50 through 55 are cammed axially out of engagement with disc 24 and the stationary contacts during the very earliest portion of a degree shifting movement say within the iirst 5 degrees of movement. After the rotary contact structure has been turned through approximately 180 degrees, elements 66 again coincide essentially with the V-shaped detent recess formed by cam surfaces 65 of element 64, so that plates 25 and 44 and the movable contacts are then freed to again shift axially toward plate 24 and into Contact with the stationary contacts 32 through 35. Also, the engagement of elements 66 with cam surfaces 65 serves to effectively locate and retain the rotary cam structure in its two predetermined contacting positions which are oiset relatively 180 degrees. Cam element 64 retains the rotary contact structure in its axially retracted position during the entire rotary movement, allowing the movable contacts to engage the stationary contacts only at the ends of that rotary movement. In the two actuated positions 0f the switch mechanism, the movable contacts Sil through 55 are yieldingly urged against and into positive engagement with the stationary contacts by springs 59, heads 60 of the movable contacts being retracted through a short distance axially away from plate 25.

I claim:

l. A switch for reversing an output circuit of an electrical generator comprising first contact means, second ccontact means mounted for rotary movement about a predetermined axis vbetween different positions relative to said iirst contact means and adapted to engage said first contact means differently in said diiferent positions to thereby reverse said output circuit, means for rotatively shifting said second contact means in opposite directions relative to the first contact means and between said positions in response to reversals in the direction of rotation of said generator, and means acting to displace said first and second contact means relatively apart in essentially the direction of said axis during said rotational shifting of the second contact means relative to the first.

2. A switch as recited in claim l, in which said last mentioned means comprise cam means acting to cam said first and second contact means relatively axially apart as a result of said rotary shifting of the second contact means.

3. A switch as recited in claim 2, in which said cam means are constructed to function as detent means for yieldingly retaining said second contact means in said dii'rerent rotary positions.

4. A switch as recited in claim 1, including a plate carrying said second contact means and rotatable therewith between said different positions.

5. A switch as recited in claim l, including a member carrying said second contact means and rotatable and axially displaceable therewith relative to said rst contact means, and means mounting said second contact means for limited axial movement relative to said member.

6. A switch as recited in claim l, including a member carrying said second contact means and rotatable and axially displaceable therewith relative to said tirst contact means, means mounting said second Contact means for limited axial movement relative to said member, and means yieldingly urging said second contact means axially relative to said member and toward said first contact means.

7. A switch as recited in claim l, including a movable member carrying said second Contact means and rotatable and axially displaceable therewith, said last mentioned means of claim l comprising cam means acting to retract said member and said carried second contact means axially away from said first Contact means as a result of rotary shifting movement of said member, there being means mounting said second contact means for limited axial movement relative to said member, and spring means avr/fano? yieldingly urging said second contact means axially relative to said member and toward said first contactmeans.

8. A switch as recited in claim' 7, including additional spring means yieldingly urging said member axially towardsaid iirstcontact means.

9. A switch ,as recited in claim l, inwhich said means for rotatively shifting said second contact means comprise spring urged centrifugally actuable 'pa-wl means rotating with said generator, and mea-nsconnected to said second contact means and presenting shoulders engageable by said pawl -means to turn said second contact means in reverse directions as. a result ofareversals'inthe direction of rotation of the generator.

110. A switch for reversing an output circuit of an electrical generator comprising a iirst stationary member adapted to beV mounted at a location axially opposite an end of the generator shaft, a. plurality of stationary contacts mounted to said rst member, a second member mounted axially Ybetween said rst member and the `shaft and rotatable .relative tov the iirst member between two dierent positions, moveable circuit reversing contacts carried by and Irotatable with said second member and adapted to engage said stationary contacts differently in said different rotary positions to reverse said `output circuit,- a unit to be connected to said generator shaft land operable to rotatively shift said second ,member andmovable contacts in opposite directions between saidvdiierent positions in response to reversal-s in the direction oirotation of the shaft, and cam means on said rst and second members operable to camthe latter axially away from the former during and as a result of rotary shifting-movement of the secondmember.

1l. A switch as recited in claim 10, including means mounting said movable contacts for limited individual axial movement relative to said second member, springs urging said movablecontacts axially relative Ito said second member and toward the iirst member, and an additional spring urging said second memberand the carried movable contacts axially toward the Yfirst member.

12. A switch as recited in vclaim 11, in which said unit includes an element adapted to be attached to and eX- tend outwardly in opposite directions, from said generator shaft, and a pair of spring urged centrifugally actu- 3 ated pawls carried by said-element Aand adaptedto engage coacting .shoulders on said second member to rotatively shift the latter, there being a `pawl, .release cam carried by said iirst. member -for releasingsaid pawls from'engagement-with said-shoulders after the-second member reaches a predetermined one of-saidpositions.

13. A switch as. recited in claim 12, in which said cam means are constructed to serve as detent means for yieldingly retaining said second member in said rotary positions.

14. A switch as recited in claim 10, including a mountingplatey adapted to be attached to an end of the generator for attaching the switch thereto, `means mounting said first member to said plate in outwardly spaced relation thereto, and a-shaft projecting from said second ,member toward said plate and mounting said second member for its rotary shifting movement.

15. An electrical reversing switch comprising a rst section having first andsecond contacts to be connected to, a firstl pair of external lines; said first section having a third .contact connected to said second contact; said section having third and; fourth contacts adapted to be connected to a second pair-of lines; a second section having sixth, seventh, eighth, ninth, rtenth and eleventh contacts; means mounting one of said sections for rotary movement Arelative to the otherfbetween two predetermined positionsrelatively odset degrees; said first, second, third, founth and iifth contacts being engaged electrically with said sixth, seventh, eighth, ninth and tenth contacts respectively in aiirst of said positions; said rst, second, third, fourth, and ifth contacts being engaged with said eleventh, tenth, ninth, eighth, and seventh contacts in said second position; and means electrically connecting said sixth contact to said ninth contact, said seventh contact to said eleventh contact, and said eighth contact to said ninth contact.

ReferencesCited in thele of this patent UNITED STATES PATENTS 796,749 McElroy Aug. 8, 1905 931,613 Jackson Aug. 17, 1909 2,483,122 Bower Sept. A27, 1949 2,604,566 Callsen et al July 22, 1952

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