US2431929A

US2431929A - Switch mechanism

Info

Publication number: US2431929A
Application number: US504422A
Authority: US
Inventors: Robert W Goff
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1943-09-30
Filing date: 1943-09-30
Publication date: 1947-12-02
Anticipated expiration: 1964-12-02

Description

. 2, 1947. R. w. GOFF SWITCH MECHANISM Filed Sept. so, 1943 2 Sheets-Sheet 1 m m 0 m m m m 0 0 0 Inventor: Robert W.Goff,

His ttorney.

D c. 2, 1947 R. w GCFF SWITCH MECHANISM Filed S 30' 1943 2 Sheets-Sheet 2 M 3s E 5% r-ii ztt y Patented Dec. 2, 1%47 swrrcn MECHANISM Robert W. Golf, Schenectady, N. Y.. assignor to General Electric Company, a corporation of New York Application September 30, 1943, Serial No. 504,422

9 Claims. 1

My invention relates generally to switch mechanisms and particularly switch mechanisms arranged for actuation by a rectilinearly movable member, such as a traveling nut. Such traveling nut switches are commonly used as limit switches, control switches, and the like where it is desired to actuate the switches in accordance with the position of a control member.

Generally stated, it is an object of my invention to provide a new and improved switch actuating member which is simple in construction and arrangement, accurate and reliable in operation, and composed of a small number of parts easily assembled at low cost thereby rendering the device particularly adaptable for standard production in large quantities. a

It is a particular object of my invention to provide a switch mechanism of the lost motion type arranged for actuation in opposite directions by a traveling operator without appreciable or significant difierential between the positions of the operator upon actuation in opposite directions.

It is a still further object of my invention to provide a switch actuating mechanism of the traveling, operator type such that the operator shall be capable of actuating any desired number of switches in its path of travel without the necessity for special means to reset the moving operator to operative position after its engagement with each switch.

It is a still further object of my invention to provide a traveling nut switch actuating mechanism wherein the nut shall be capable of passing a previously actuated switch without damage to the switch or the traveling actuator and shall in so passing maintain a position of immediate readiness for reverse actuation of the same switch mechanism by the traveling nut.

According to the invention, a switch such as an overcenter snap-action switch having a certain necessary lost motion between switch actuating positions, is arranged for actuation by a traveling operator through an overtravel mechanism interpo's'ed-between the switch arm and traveling operator. The overtravel is made to substantially fully compensate for the lost motion of the switch itself, so that the traveling operator experiences no positional'difierential between forward and reverse switch actuation.

My invention will be more fully understood and its objects and advantages further appreciated by referring now to the following detailed specification taken in conjunction with the accompanying drawings in which Fig. 1 is a plan view of a traveling nut switch assembly shown with the casing cover partly broken away; Fig. 2 is a sect onal view taken along the line 2-2 of Fig. 1; Fig. 3 is a sectional view taken along the line 3-3 of Fig. 1; Fig. 4 is a sectional view taken along the line 4-4 of Fig. 3; Figs. 5 and 6 are elevational views of one of the switch mechanisms shown at Figs. 1-4; Figs. '7 and 8 are fragmentary side elevations taken in the direction 1-! of Fig.

- 6 and showing two types of switches included in the assembly of Fig. 1; and Fig. 9 is an exploded perspective view of a single switch actuating mechanism of the type included in Figs. 1-8 and embodying my invention. Referring now to the drawings, and particularly to Figs. 1-4 inclusive, I have shown a switch assembly comprising a plurality of switches arranged side by side for sequential actuation by a traveling nut in accordance with the angular position of a rotatable threaded shaft. Such a switch assembly may suitably be used to control any electric translating apparatus, such as to limit the extent and otherwise control the operation of an electric motor and the like. By way of example, in crane "or bridge hoist equipment, the switches at the extremities of travel of the traveling nut may be connected to limit rotation of the driving motor in opposite direction, the next adjacent switches at both ends may-be ar; ranged to slow down the motor as it approache the limit of its operation, and the intermediate switches may be used for any desired control function, such as the control of warning lights, traffic lights, safety gates and the like.

The switch assembly of Figs. 1-4 is mounted in a casing it) having a cover I I. The casing Ill being provided at opposite ends with suitable bearings Illa and lb for rotatably supporting a threaded shaft i2 and is provided internally with suitable switch supporting bars I 3, I 4 and track members l5, l6 disposed in parallel spaced relation with respect to the threaded shaft l2. The threaded shaft lz'extends at one end through the casing ID for connection to a control member (not shown) and is in threaded engagement with a longitudinally slidable carriage l1 within the casing i0. upon the spaced track members [5 and I6 and is formed to provide a pair of integral depending threaded collars i8 and I9 which threadingly engage the shaft l2 at spaced points along the shaft. Upon the upper surface of the carriage H are formed a plurality of switch operating bosses 20, 2|, 22, and 23, the construction and function of which will be more fully described hereinafter.

As explained above, the shaft engaging portions The carriage l1 rests at opposite sides of the carriage I! are formed as two spaced threaded collars 8 and I9 rather than a single collar of equal total engaging area. The purpose of this arrangement is to avoid weakening of the driving force over a considerable distance prior to the arrival of the threaded nut or collar at the limit of its travel. To limit the travel of the carriage ll, the shaft I2 is stripped of its threads at both ends, as indicated at 24 and 25, and at two intermediate portions 26 and 21 spaced from the ends by distances equal to the spacing between the collars I8 and 9. It will be evident that with a single relatively long engaging collar on the carriage I! the driving fOrCe would be continuously diminished for a considerable distance at both limits of travel of the carriage as the threads on the collar ran off of the threaded portion of the shaft. By using instead two engaging collars, each of only half the total desired length, more effective engagement between the collars and the shaft may be maintained up to the limit of travel. With such an arrangement, the distance preceding the limit of travel over which the threads become disengaged is immediately reduced to half that of the equivalent single collar, while at any predetermined distance from the limit of travel the area of threaded engagement is doubled.

Mounted upon the longitudinal supporting bars I3 and I4 on opposite sides of the threaded shaft l2 and in operative relation with the operating bosses 2023, inclusive, on the carrier I1, I provide a plurality of electric switches 28, 29, 30, 3|, 32, and 33. By way of example, I have shown the switches 283| mounted on one side of the shaft upon the supporting bar l3 and the two switches 32 and 33 mounted upon the opposite side of the shaft upon the bar M. It will be evident to those skilled in the art that the switches 28-33, inclusive, are only representative of any desired number and arrangement of switches. All these switches are of similar construction, so that only one switch will be described in detail.

Referring now particularly to Figs. 5, 6, and 9, the switches 28-33, inclusive, each comprises a base 40 of suitable molded insulating material upon one side of which are mounted the cooperating switch contacts and upon the other side of which is mounted the switch operating mechanism. The switch may of course be provided with a suitable cover (not shown). As shown at Fig. 5, the, contact structure includes a plurality of stationary contacts 4|, 42, 43, and 44 and a movable bridging contact member slidably mounted upon a transverse rod 46 for engagement with either the contacts 4| and 42 or the

contacts

43 and 44. For moving the bridging contact 45 along the bar 46, I provide a U-shaped yoke 41 slidably mounted upon the bar 46 with its legs on opposite sides of the bridging contact 45. The bridging contact 45 is resiliently centered between the legs of the yoke 41 by means of a pair of compression springs 48 and 49 positioned between the contact 45 and opposite legs of the yoke 41. The yoke 41 is also provided at its bight with an extending pin 50.

The base 40 is bored near the upper end, as viewed in the drawings, to provide a journal bearing for a transverse rocker shaft 5|. of the shaft 5| extends outwardly from the contact side of the base and carries a depending arm 52 which is slotted at 53 slidably to receive the pin on the yoke 41. Through this pin and slot connection the arm 52 moves the yok 41 and bridging contact 45 along the supporting bar 46. The opposite end of the rocker shaft 5| extends One end outwardly from the other side of the base and is connected to a rocker arm 54. As shown particularly at Figs. 6 and 9, the rocker arm 54 is arranged to engage at opposite ends a pair of notched latch levers 55, 56. The latch levers 55. 56 are pivotally mounted upon fixed pivots 5'! and 58, respectively, in the base 40 and biased toward the rocker arm 54 by a pair of compression springs 59 and 60 respectively. The latch levers 55 and 56 are provided internally with latching shoulders GI and 62 and stop shoulders 6|a and 62a, respectively, each of which are alternatively engageable with opposite ends of the rocker arm 54 in a manner hereinafter'to be described in greater detail.

The rocker arm 54 and the latch levers 55 and 56 are controlled by a pivoted switch arm 63 which is rotatably mounted upon a fixed pivot 64 in the base 40 and carries at its movable end a spring thread ball 65 arranged for longitudinal sliding engagement along the rocker lever 54.

Briefly, the operation of the switch mechanism thus far described will be evident from a consideration of Fig. 6. Let it be assumed that by some suitable means the switch arm 63 is moved in a counterclockwise direction so that the spring-pressed ball 65 slides along the rocker arm 54 from the high to the low side of the rocker arm and transversely of the center line of the shaft 5| As the spring-pressed ball passes the center line of shaft 5|, it places a clockwise bias upon the rocker arm 54, but the rocker arm cannot move in a clockwise direction by reason of its engagement with the latching shoulder 6|. However, upon further movement the side of the switch arm 63 engages the latch lever 55 and moves it against its bias out of engagement with the end of the rocker arm 54. As soon as the rocker arm 54 is released by the latching shoulder 6|, the rocker arm rotates in the clockwise direction through a small angle and until it comes into engagement with the stop shoulder 6| a on the latch lever 55. Referring now to Fig. 5, it will be observed that such rotation of the rocker arm 54 (counterclockwise as viewed at Fig. 5) causes the depending arm 52 to shift the U- shaped yoke 41 and'bridging contact 45 to the right as viewed at Fig. 5 thereby to open the

contacts

43 and 44 and close the contacts 4| and 42 with a snap action. The switch structure described above and comprising a rocker arm, pivoted switch arm, and a pair of latch and stop levers is described and claimed in my copending application, Serial No. 471,137, filed January 2, 1943, and assigned to the same assignee as the instant application.

As previously stated, the switch arm 63 is pivotally mounted upon the fixed pivot 64. As shown at Fig. 9, the pivoted end of switch arm 63 is bifurcated and provided at its bight with a spring-pressed ball 66. As illustrated at Fig. 9, the spring-pressed balls 65 and 66 are positioned within a suitable bore in the switch arm 63 and biased outwardly by an interposed compression spring 61. For cooperation with the spring-pressed ball 66, I provide an actuating lever or plate 68 which is pivotally mounted upon the fixed pivot 64 between the bifurcated ends of the switch arm 63. The upper end of the actuating lever 68 is provided with a pair of upright ears 69 and 10 for cooperation with the sides of the switch arm 63 to limit relative rotation of the switch arm and actuating lever, Intermediate the ears 69 and 10, the switch lever 68 is formed to provide a pair of adjacent notches H and 72 for cooperation with the spring-pressed ball 66, releasably to retain the actuating lever 68 in one of two angularly displaced positions with respect to the switch arm 63.

Referring now to Figs. 1-4, it may be observed that each operating boss 20-23, inclusive, upon the carriage I1 is provided at opposite sides with spring-pressed spherically headed engaging member 15, 16. As shown particularly at Fig. 4, the member 16 may be a hollow spherically headed pin pressed upwardly in the bosses 20-23 by means of a compression spring 11. The member is similarly constructed and arranged. The spring-pressed members 15 and 16 on the carriage H are positioned cooperatively to engage the actuating levers 68 of the switches 28-33, inclusive, and for this purpose the switch actuating levers 68 are notched at their lower ends at I8, as indicated at Fig. 9. The springs 11 are made sufficiently strong to overpower the springs 61 when their forces are opposed.

It may be observed from Fig. 1 that the springpressed operating members I5 and I6 in the various bosses -23, inclusive, are spaced differently from the center line of the threaded shaft l2. Thus, the engaging members 15 and 16 in the various bosses travel along separate parallel lines as the carriage H is moved along-the shaft l2,

and each engaging member will actuate only those switches having their actuating levers or plates 68 positioned in the line of movement in that particular engaging member. At Figs. '7 and 8, I have shown one manner in which selected switches may be aligned for operation by selected engaging members 15 or 16. Fig, 8 shows a fragmentary side view of the lower end of one switch, such as the switch 28, in which the actu- W ating plate or lever 68 is planar, such as that shown at Fig. 9. At Fig. '7, however, I have shown a similar fragmentary view of the assembly mounted upon the pivot pin 64 and have shown an actuatin lever 68 which is offset away from the base 40 below the pivot pin as at. 19 so that it will be moved by the spring-pressed engaging member 75 on the boss 2| and will be by-passed by all the other engaging members. Similarly, the planar actuating lever 68 of Fig. 8 may be arranged to be moved by the engager 15 on the boss 22. Furthermore, the actuating levers 68 on some of the switches may be offset toward the base 40, such as those shown at Fig. 4, thereby to be moved by still a third spring-pressed engager such as the member 15 on the boss 23. The engagers l5 and 16 on the boss 20 are in line with those on the boss 23 in the embodiment of the invention illustrated.

In view of the. foregoing detailed description of the construction and arrangement of the vari ous parts of my switch mechanism, its mode of operation will now be evident from the following brief description.

The action of a single switch under the influence of its cooperating engaging member on the carriage I! may be understood by referring particularly to Figs. 2 and 6 and considering the action of the switch 3| and the cooperating springpressed engager 15 on the carriage boss 2|. Let it be assumed that the switch 3| is in the position shown at Fig. 2 and that the boss 2| is approaching the switch from the left as shown in the drawing. In the position shown, the rounded ball like end of the member '15 will have just come into complete engagement with the notch I8 in the lower end of the actuating lever 68 of the switch 3|. Now because of the ball and notch 6 engagement between the switch arm 63 and the actuating lever 68, these members move as a unit in the counterclockwise direction as the engager 15 on the boss 23 continues its movement to the right, as viewed at Fig. 2. Due to the angular displacement between the switch arm 63 and the actuating plate 68, the plate will be in approximately its mid position when the arm 63 disengages the latch lever 55 to release the rocker arm 54 in the manner heretofore described. Immediately after actuation of the rocker arm, the switch arm 63 is brought against a fixed stop provided by the latch lever 55, which is now solidly in engagement with a portion of the base. Thus, the switch arm 63 can move no further. However, the spring-pressed engager l5 is still in engagement with the latch lever 68 and, due to the fact that the spring I! is sufficientl strong to overpower the spring 61, the actuating plate or lever 68 continues to move in a counterclockwise direction thereby forcing the ball 66 out of the notch H and into the notch 12., This overtravel of the actuating plate 68 reverses the relative angular displacement of the arm 63 with respect to the plate 68 and rotates the notch 18 in the lower end of the plate sufficiently to permit the release of the spring-pressed engager l5 and the carriage I1, is free to continue its movement without further effect upon the switch 3|.

Operation of the switch 3| in the reverse direction and 'back to the position of Fig. 6 is entirely similar in nature. It is to be particularly noted that upon reverse movement the actuating plate 68, being angularly displaced to the left of the arm 63, is again substantially in its mid position when the arm 63 releases the latch lever 56.

' Compare the positions of switches 2830 at Fig. 2.

In the switch assembly shown in the drawings by way of illustration, the spring-pressed engag ing members 15 and I6 on the various carriage bosses are arranged to,travel in three parallel lines on each side of the center of the threaded shaft l2. Referring to Fig. 1, it will be evident that the spring-pressed members 15 and won the boss 22 travel in parallel lines equally spaced on opposite sides of the center of the shaft l2 and actuate the switches 30 and 32, respectively, having planar actuating plates 68. pressed members 15 andf|6 on the carriage boss 23 and the carriage boss 20 are spaced farther out from the center of the shaft l2, the members 15 on the bosses 20 and 23 actuating the switches 28 and 3|, respectively, and the engager 16 on the boss 23 actuating the switch 33. Finally the spring-pressed engagers 15 and 16 on the carriage boss 2| are set closer to the center of the shaft than are those on the boss 22 and the engager 15 of this boss is arranged to actuate the switch 29. It will be evident to those skilled in the art that this arrangement is illustrative only, and that any desired positioning of the switches and correlation of the switches and the traveling engagers may be arranged in accordance with particular circumstances. It will also be evident that a single spring-pressed engager may be arranged to actuate more than one switch in the course of its travel from one end of the shaft The spring- 7 mechanisms to experience a certain differential in the position of the traveling nut between forward and reverse operation of the switch in order to take up the necessary lost motion in the overcenter mechanism. According to my invention,

'shown and at the instant of release of the rocker lever 54, that is, before overtravel of the plate 68 has occurred to bring it to the final solid line position of Fig. 6. It will be evident from this drawing that at the instant of tripping in the clockwise direction of movement of the switch arm 63, the actuating plate 68 is approximately in a central position. Now, it may also be observed from Fig. 6 that, with the parts in the solid line positions shown and upon counterclockwise movement of the arm 63 and plate 68, the plate 68 will again be in substantially its central position at the instant ofrelease of the rocker arm 54. It will be borne in mind that when the switch is actuated, the switch arm and actuating lever move together until the switch arm 63 comes against the stop provided by the latch lever 55 or 56. It is to be noted that the angle of overtravel of the lever 68 with respect to the arm 63 is substantially equal to the angle between the spaced switch operating positions of the arm 63. It will now be clear that, regardless of the direction of actuation of the switch arm 63, the actuating plate 68 is in its'mid position at the instant of tripping of the switch. This means that tripping in either direction always takes place with the engager 15 or 16 in a predetermined fixed position longitudinally of the shaft l2. Accordingly, despite the fact that the switch arm 63 itself has a certain amount of back-lash between its forward and reverse tripping positions, such backlash is .-not evident to the traveling carriage I'l, so that each switch is operated in forward and reverse directions with no appreciable. differential in positions of the carriage [1.

While I have described only'a preferred embodiment of my invention by way of illustration, many modifications will occur to those skilled in the art and I, therefore, wish to have it understood that I intend in the appended claims to cover all such modifications as fall within the true spirit and scope of my invention.

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

1. A switch mechanism comprising a switch arm pivotally mounted upon a fixed pivot for movement between angularly spaced switch actuating positions, said angular spacing constituting a predetermined lost motion between said positions, a reversible traveling operating member movable transversely of said fixed pivot to actuate said switch mechanism, and an actuating member rotatably mounted on said fixed pivot and coupled to said switch arm for movement between two angularly displaced alternative positions with respect to said switch arm, said actuating member being arranged upon initial significant movement of said operating member to take up said lost motion and to actuate said switch member and upon continued movement of said operating member to overtravel between said alternative positions to release said traveling operator and to reset said ctuating member for return actuation of said switch mechanism.

2. A switch mechanism comprising a switch arm pivotally mounted upon a fixed pivot for movement between angularly spaced switch actuating positions, said angular spacing constituting a predetermined lost motion between said positions, a reversible traveling operating member movable transversely of said fixed pivot to actuate said switch mechanism, and a rotatable actuating member rotatably mounted on said fixed pivot and coupled to said switch arm for, movement between two angularly displaced alternative positions with respect to said switch arm, said actuating member being arranged upon initial significant-movement of said operating member to take up said lost motion and actuate said switch mechanism and upon continued movement of said operating member to overtravel between said alternative positions to release said traveling operator and to reset said actuating member for return actuation of said switch mechanism, said angular overtravel being substantially equal to and arranged substantially fully to compensate for said angular lost motion thereby to effect actuation of said switch mechanism at substantially the same position of said operating member in both directionsof travel.

3. A switch mechanism comprising a switch arm pivotally mounted upon a fixed pivot for movement with predetermined angular lost motion between spaced switch actuating positions, an actuating member pivotally mounted upon said pivot, means interconnecting said switch arm and said actuating member releasably to maintain said switch arm in either of two angularly displaced positions with respect to said actuating member and to provide a predetermined angular overtravel therebetween, and a reversible traveling operating member arranged to engage said actuating member to actuate said switch mechanism, said overtravel substantially fully compensating for said lost motion thereby to effect forward and reverse actuation of said switch mechanism at substantially the same position of said operating member in both directions of travel.

4. A switch actuating mechanism comprising a switch arm pivotally mounted upon a fixed pivot for movement between angularly spaced switch actuating positions, a switch actuating lever rotatably mounted upon said pivot, means for re-- leasably maintaining said switch actuating lever in either of two alternative angularly displaced positions with respect to said switch arm, and means for engaging said actuating lever to move said lever and arm in unison between said switch operating positions and thereafter to move said lever relative to said arm between said alternative positions.

5. A switch actuating mechanism comprising a switch arm pivotally mounted upon a fixed pivot for movement between angularly spaced switch actuating positions, stop means for defining said positions, a switch actuating lever rotatably mounted upon said pivot, resilient means for releasably retaining said switch actuating lever in either of two alternative angularly displaced positions with respect to said switch arm, and means for engaging said actuating lever to move said lever and arm in unison until said arm engages said stop means and thereafter to move said lever relative to said arm between said alternative positions.

6. A switch actuating mechanism comprising a switch arm pivotally mounted upon a fixed pivot for movement between angularly spaced switch actuating positions, a switch actuating lever rotatably mounted upon said pivot, means for releasably retaining said switch actuating lever in either of two alternative angularly displaced positions with respect to said switch arm, the displacement angle between said alternative positions being substantially equal to the displacement angle between said switch actuating positions, and means movable reversibly and transversely of said fixed pivot to engage said actuating lever for moving said lever and arm in unison between said switch actuating positions and thereafter effecting overtravel of said lever with respect to said arm between said alternative positions, whereby forward and reverse switch actuation is effected without significant differential in the positions of said transversely movable member in its path of travel.

'7. A switch actuating mechanism comprising a switch arm pivotally mounted upon a fixed pivot for movement between two angularly spaced switch actuating positions, an actuating lever rotatably mounted upon said pivot, lost motion connecting means between said arm and said lever arranged releasably to hold said lever in either of two angularly displaced positions with respect to said arm, the angular lost motion of said lever being substantially equal to the angular movement of said switch arm between said switch actuating positions, and a reversible engager movable rectilinearly and transversely of said pivot into engagement with said actuating lever to move said lever and said arm in unison between said switch actuating positions of said arm and thereafter to effect overtravel of said lever to release said engager and to reset said lever for reverse actuation of said switch at substantially the same position in the path of travel of said engager.

8. A switch actuating mechanism comprising a bifurcated switch arm pivotally mounted at its open end upon a fixed pivot for movement between two angularly spaced switch actuating positions, an actuating member rotatably mounted upon said pivot between the spaced sides of the bifurcated end of said switch arm, a spring pressed ball and multiple recess connection between said switch arm and said actuating lever arranged releasably to retain said lever in either of two alternative angularly displaced positions with respect to said arm, the displacement angle between said alternative positions being substantially equal to the displacement angle between said switch actuating positions thereby to compensate the lost motion of said switch arm between said switch actuating positions, and a reversible traveling operating member movable transversely of said fixed pivot and arranged to engage said switch actuating member for moving said switch arm and actuating member in unison between said switch actuating positions and thereafter effecting overtravel of said member with respect to said arm between said alternative positions, whereby forward and reverse switch actuation is effected without significant differential in the position of said traveling operating member in its path of travel.

9. A switch actuating mechanism comprising a bifurcated switch arm pivotally mounted at its open end upon a fixed pivot for movement between two angularly spaced switch actuating positions, an actuating plate rotatably mounted upon said pivot between the spaced sides of the bifurcated end of said switch arm, said plate being formed to provide a pair of spaced peripheral notches in juxtaposition to the bight of said bifurcated end of said switch arm and a third peripheral notch outside said bifurcated end, a spring pressed ball disposed within said bight alternatively to engage said notches thereby releasably to retain said actuating plate in either of two alternative angularly displaced positions with respect to said switch arm, the displacement angle between said alternative positions being substantially equal to the displacement angle between said switch actuating positions, a reversible traveling spring pressed engager movable transversely of said fixed pivot and arranged to cooperate with said third peripheral notch to rotate said actuating plate about said pivot, the spring pressure of said engager being suflicient to overcome the spring pressure of said ball thereby to move said actuating plate and said switch arm in unison between said switch actuating positions of said arm and thereafter to effect overtravel of said plate with respect to said arm between said alternative positions.

ROBERT W. GOFF.

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

UNITED STATES PATENTS Germany May 5, 1933