US2369964A

US2369964A - Switch actuating mechanism

Info

Publication number: US2369964A
Application number: US517813A
Authority: US
Inventors: Robert W Goff
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1944-01-11
Filing date: 1944-01-11
Publication date: 1945-02-20
Anticipated expiration: 1962-02-20

Description

Feb. 20, 1945. R, w GOFF 2,369,964

SWITCH ACTUATING MECHANISM Filed Jan. 11, 1944 2 Sheets-Sheet 1 Fig.1. Fig.2.

n kumwim Inventor: Robert W. Goff,

H His Attorney.

R. W. GOFF Feb. 20, 1945.

SWITCH ACTUATING MECHANI SM 2 Sheets-Sheet 2 Filed Jan. 11, 1944 Inventor: Robert W. Goff,

His Attorneg.

Patented Feb. 20, 1945 SWITCH ACTUATING MECHANISM Robert W. Golf, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application January 11, 1944, Serial No. 517,813

8 Claims.

My invention relates to electric switch actuating mechanisms, and especially to limit switch actuating means providing for overtravel in both directions of movement of an engageable operating lever.

The invention has particular application to and has been illustrated by way of example as applied to a double-throw limit switch of the snap-action type having a switch actuating rocker lever alternatively latched in one of two predetermined spaced circuit controlling positions and slidable overcenter spring means for disengaging the latches and moving the rocker lever.

It is a general object of my invention to provide a new and improved limit switch of the above character which shall be simple in construction, inexpensive and economical to manufacture, reliable in operation, and characterized by a greatly improved operating life.

It is a more specific object of my invention to provide a new and improved switch mechanism including means for converting rotation of an engageable operating lever about one axis to rotation of a switch actuating member about a perpendicular axis while permitting overtravel of the operating lever in both directions with respect to the actuating member.

My invention itself, together with further objects and advantages thereof, may be fully appreciated by referring now to the following detailed specification taken in conjunction with the accompanying drawings, in which Fig. 1 is a front elevational view of a limit switch embodying my invention in one form; Fig. 2 is a cross-sectional view taken along the line 2-2. of Fig. 1 looking in the direction of the arrows; Fig. 3 is a rear elevational view of the limit switch of Figs. 1 and 2; Fig. 4 is an exploded perspective View of the principal operating parts of the switch shown at Figs. 1-3; and Fig. 5 is afragmentary exploded perspective view of a part of the mechanism illustrated at Fig. 4.

Referring now to the drawings, and particularly outlet vent l6 and a tapped conduit'connection ll for the entrance of suitable electric conducting wires. 8

The double-pole double-throw limit switch illustrated in the drawings comprises two spaced pairs of stationary contacts l8 and. I9 and a movable bridging contact member 20. The bridging contact 20 is slidably mounted upon a rectangular contact supporting bar 2| and i resiliently held in acentral position within a slidable yoke 22 by a pair of helical compression springs 23 positioned between the contact member 20 and the parallel sides of the yoke. As clearly shown at Fig. 4:, the yoke 22 is slidably mounted upon the contact supporting bar 2!. For the'purpose of sliding the yoke 22longitudinally of the bar 2! to move the bridging contact 28, I have pro'v'ided'a pin 24 extending rearwardly from the bight of the yoke 22 into a slot 25 of a pivotally mounted switch arm 2-6. The arm 25 forms part of a switch member comprising a rocker shaft 21 fixedly connected at one end to the arm 26 and at the other end to the center of a rocker lever 28. The rocker shaft 21 is rotatably journaled intermediate its ends in the casing partition or dividing wall II. The rocker lever 28 forms apart of the switch actuating mechanism and lies in the compartment I5.

The switch actuating mechanism will be best understood by referring now particularly to Figs. 3 and 4. From Fig. 3, it will be observed that a pair of latch levers 29 and 30 are pivotally mounted upon pivot pins 3| and 32, respectively, in the base I0 and are biased into engagement with opposite ends of the rocker lever 28 by means of associated helical compression springs 33 and 3 4. respectively. The

springs

33 and 34 are seated in

casing abutments

35 and 36, respectively, which serve to limit the latch disengaging movement of the associated latch members. i

Each

latch member

29 and 30 is provided with a latching shoulder 31 with which the opposite ends of the .rocker lever 28 are alternatively engageable. Each

latch lever

29 and 30 is also provided with a limit stop shoulder'38 with which the opposite ends of the rocker lever 28 are also alternatively engageable in inverse relation with respect to the latch shoulders 31. That is, when the latch shoulder 31 of the lever 30 is in engagement with one end of the rocker lever 28 as shown, the stop shoulder 38 of the other lever 29 is in engagement with the opposite'end of the rocker lever 28. Conversely, the latch shoulder 31 of the lever 29 and the stop shoulder 38 of the lever 30 will be simultaneously'effective when the rocker lever 28 is in its other circuit controlling position. The operation of the rocker lever 28 and the function of the latch and stop

shoulders

31 and 38 will be more clearly understood after the remainder of the operating mechanism has been more fully described.

The rocker lever 28 is actuated with a snapaction between two angularly displaced limiting circuit controllin positions by means of an overcenter mechanism comprising a spring pressed ball or roller. 39 mounted in the movable end of a pivoted actuating lever 40 for sliding movement longitudinally of the rocker lever .28 and overcenter with respect to the rocker shaft'21. The ball 39 is biased outwardly from the end of the lever 40 by a helical compression spring 4| positioned within a counterbore in the lever 40. The actuating lever 40 itself is shown as having a rectangular cross-section, and is pivotally mounted upon a fixed pivot pin 42 in the casing Hi.

Attached to the actuating lever 40 is a clutch arm comprising an'oifset portion 43. extending from the pivot pin 42 substantially longitudinally of an operating shaft 41. The operating shaft 41 is disposed substantially perpendicular to the pivot pin 42 and has fixed thereto a longitudinally grooved substantially cylindrical hub 46. Releasable clutching engagement between the operating shaft 41 andthe actuating lever 40 is effected by a clutch pin 44 attached to the offset portion 43 of theclutch arm and extending substantially perpendicular to the operating shaft 41 into engagement with the grooved surface of the hub 46. The clutch pin 44 is hollow, or may be counterbored at its end, to receive a springnressed ball 45 which, together with the grooved hub 48, constitutes a releasable overriding ball and socket clutching connection between the operating shaft 41 and the actuating lever 40.'

The hub 48 is shown in greater detail at Fig. 5, and comprises a cylindrical body portion grooved longitudinally at 48 along one side and enlarged at one end to provide a pair of oppositely disposed

stop shoulders

49 and 50. At a portion of reduced cross-section axially displaced from the

stop shoulders

49 and 50 and the grooved cylindrical portion, the hub 46 is provided with a radially extending arm A c-shaped leaf spring 52 is positioned circumferentially of the hub 46 and to grasp the arm 5| firmly between the open ends of the spring. While it is of course not necessary that the hub 46 be of reduced cross-section in the region of the arm 5|, such reduction of cross' section is desirable so that the diametrical dimension of the C-shaped spring 52 may be approximately the same as the diameter of the grooved cylindrical portion of the hub 46.

Referring now again to Figs. 2 and 4, it will be observed that the operating shaft 41 is positioned parallel to the internal dividing wall II and sufficiently closely thereto that the

stop shoulders

49 and 50 on the hub 46 will engage the dividing wall to limit the rotation of the operating shaft 41 in both directions. Mounted upon the dividing wall II I also provide a fixed stop member 53 having a pair of spaced-apart dogs 54 of substantially the same width as the radial arm 5| on the hub 46. The dogs 54 are arranged on opposite sides of the arm 5| and between the open ends of the c-shaped spring 52. Thus, when no operatin torque is applied to the shaft 41, the C-shaped spring 52 tends to close upon opposite sides of the fixed dogs 54 and to hold the radial arm 5| of the hub in a normal position between the dogs 54. The fixed stop member 53 carrying the dogs 54 is slotted at 55 to provide for adjustable mounting upon the casing III by means of a bolt 55'. It will therefore be evident that the normal position of the operating shaft 41 may be changed within limits by adjusting the position of the fixed stop 53 upon the casing Hi.

It may now be observed from Figs. 1 and 3, that the operating shaft 41 extends through a wall of the casing ID to the outside thereof and carries at its outer end an operating arm 56 upon the end of which may be mounted an engaging roller 51. As illustrated in the drawings, the operating arm or lever 56 is preferably mounted upon the operating shaft 41 by means of a pair of serrated hubs, one upon the shaft 41 and one upon the arm 56, arranged to be locked in engagement in any one of a plurality of positions by means of a bolt 59.

From the foregoing detailed description of the various parts of my switch mechanism and the manner of their organization into a unitary whole, it is believed that the operation of the device will be evident from the following brief description. Assuming that initially the mechanism is in the position shown in the drawings,

and referring particularly to Figs. 2, 3 and 4, movement of the bridging contact 20 from the position shown and into engagement with the contacts i9 is effected by movement of the operating arm 56 and shaft 41 in a counterclockwise dir'ection, as viewed at Fig. 4. Counter-clockwise rotation of the shaft 41 and the attached hub 44 moves the pin 44 on the lever 42 downwardly, as viewed at Fig. 4, by reason of the engagement of the ball 45 with the socket or groove 46. Downward movement of the pin 44 effects counterclockwise rotation of the actuating lever 40 about its pivot pin 42. Such counterclockwise rotation of the shaft 41 and attached hub 46 also causes the radial arm 5| on the hub to spread the C-shaped spring 52 by moving the lower end of the spring, as viewed at Fig. 4, away from the fixed clogs'54, while leaving the upper end of the spring in engagement with the upper sides of the dogs. The counterclockwise rotation of the actuating lever 40 thus effected continues until the free end of the lever 40 strikes the latch lever 30. During this movement, the ball 39 is moved inwardly against the force of the spring 4| and overcenter with respect to the rocker shaft 21. However, the rocker lever 28 is not moved immediately because of its latching engagement with the shoulder 21 of the latch lever 36. As soon as the actuating lever 40 strikes the lever 30 and moves it to its latch disengaging position against the abutment 36 the rocker lever 28 is unlatched and the spring 4| becomes eifective to rotate the rocker shaft 21 in a clockwise direction, as viewed at Fig. 4, until the right side of the rocker lever 28 engages the limit stop shoulder 38 of the lever 30. In this position it will be clear, by analogy with Fig. 3. that the latch shoulder 31 of the latch lever 29 has moved under the left-hand end of the rocker lever 28 to lock the rocker lever in the new position. It will be understood that rotation of the rocker shaft 21 and the attached switch arm 26 produces a sliding movement of the yoke 22 and bridging contact 20 along the contact supporting bar 2|.

As mentioned hereinbefore, rotation of the operating shaft 41 in both directions from its normal position is limited by engagement of the stop shoulders 49 and 50 with the dividing wall ll of the casing I0. However, the stop shoulders 49 and 50 are so positioned upon the hub 46 that switch actuating movement of the rocker shaft 28 in both directions may be efiected before the stop shoulders 49 and 50 engage the casing; These shoulders serve, however, to limit overtravel of the operating lever 56 with respect to the actuating lever 40. For example, in the event that, after the contact actuating movement described, a further counterclockwise rotation of, the operating arm 56 is effected. the spring pressed ball 45 will be forced out of the groove or socket 48 by reason of the fact that the actuating lever 40 is now in engagement with the latch lever 30 and the latch lever 30 is in engagement with the fixed abutment 36. Thus, while no further counterclockwise rotation of the actuatin lever 40 is possible, a certain degree of overtravel of the operating shaft 41 is permitted by forcing the ball 45 out of the groove 48. This overtravel is limited only by engagement of the stop shoulder 49 with the casing ll).

If now the operating arm 55 is released, the C shaped spring 52 will assume its normal shape and bring the radial arm 51 on the hub 46 back into alignment with the protruding dogs 54 on the fixed stop 53. The operating shaft 41 and hub 46 will thus be moved in a clockwise direction, as viewed at Fig. 4, and the actuating lever 49 rotated in a clockwise direction about its pivot pin 42. Upon such clockwise rotation of the actuating lever 40, it strikes the latch lever 29 and effects snapaction of the rocker lever 28 in a manner entirely analagous to that described heretofore in connection with the latch lever 30. Such snap action of the rocker lever 28 takes place before the stop shoulder 50 on the hub 46 engages thecasing !0. If. now, the operating lever 56 is forced further in a clockwise direction, the ball 45 will again be forced out of the groove 48 and overtravel of the shaft 47 permitted until the stop shoulder engages the casing l0.

As noted hereinbefore, the normal positions of the operating shaft 41 and actuating lever in may be changed by adjustment of the fixed stop member 53. This adjustment will be more fully understood by referring again to Fig. 4. As shown at this figure, the bridging contact is in engagement with the fixed contacts [8 when the switch mechanism is in its normal position. If now it is desired to maintain the contacts ii? nor mally open and the contacts l9 normally closed,

it is only necessary to loosen the bolt 56 of Fig. 2 and slide the fixed stop member 53 downwardly, as viewed at Figs. 2 and 4. In this manner the normal position of the operating shaft 47 and hub 46 may be displaced in a counterclockwise direction from the positions shown, so that the actuating lever 40 is normally on the opposite side of the rocker lever 28 and in engagement with the latch lever 30.

From the foregoing detailed description of the structure and operation of my electric switch, the purpose and advantages of the limiting stop 38 on the latch levers 29 and Will become evident, Briefly, these shoulders definitely determine the circuit controlling positions of the rocker arm 28 without reliance upon the switch contacts themselves as limiting stops. B this arrangement, backlash in the mechanism is prevented and its operating life is considerably extended. This feature of the limit switch disclosed herein by way of illustration of a preferred embodiment of my present invention is fully described and claimed in my copending application Serial No. 471,137, referred to hereinbefore.

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 motiontransmitting overtravel mechanism comprising a base, a substantially cylindrical operating member mounted upon said base for rotation about a first axis, an actuating member pivotally mounted upon said base for rotation between two angularly spaced limiting positions and about a second axis perpendicular to said first axis, and an overriding clutch arm attached to said actuating member and offset .from said second axis longitudinally of said first axis, said arm extending into releasable clutching engagement with said cylindrical operating member, thereby positively to connect said operating and actuating members over a predetermined limited range of rotation of said operating member.

2. A motion transmitting overtravel mechanism comprising a base, a substantially cylindrical operating member mounted upon said base for rotation about a first axis, means for biasing said operating member to a selectable normal position, an actuating member pivotally mounted upon said base for rotation between two angularly spaced limiting positions and about a second axis perpendicular to said first axis, an overriding clutch arm attached to said actuating member at a point displaced from said second axis longitudinally of said first axis and extending into releasable clutching engagement with said cylindrical operatin member, and means including said biasing means for selecting said normal position normally to dispose said actuating member in either of said limiting Positions.

3. A motion transmitting overtravel mechanism comprising a base, a substantially cylindrical operating member mounted upon said base for rotation about a first axis, an actuating member pivotally mounted upon said base for rotation between two angularly spaced limiting positions and abouta second axis perpendicular to said first axis, said actuating member including an overriding clutch arm offset from said second axis substantially longitudinally of said first axis and extending substantially perpendicular to said first axis into releasable clutchin engagement with said operating member, and a pair of stop members carried by said operating member and dis-- posed to engage said base to limit overtravel of said operating member in both directions and with respect to said actuating member.

4. A motion transmitting overtravel mechanism comprising a base, a substantially cylindrical operating member mounted upon said base for rotation about a first axis, means for biasing said operating member to a selectable normal position,

an actuating member pivotally mounted upon said tation of said operating member while permitting limited overtravel thereof in both direction with respect to said actuating member, and means ineluding said biasingmeans for selecting said normal position normally to dispose said actuating member in either one of said limiting positions.

5. A motion transmitting overtravel mechanism comprising a base, a substantially cylindrical operating member rotatably mounted upon said base, a pair of stop members carried by said operating member and arranged to engage said base to limit rotation of said operating member between two predetermined angularly displaced positions, an actuating member pivotally mounted upon said base for movement between two angularly spaced limiting positions and about an axis substantially perpendicular to the axis of rotation of said operating member, and a releasable overriding clutch connection between the surface of said cylindrical operating member and a portion of said actuating member ofiset from said pivotal axis longitudinally of said cylindrical operating member, said clutch connection effecting movement of said actuating member between said limiting positions within. the limits of rotation of said operating member and permitting overtravel of said operating member in both directions.

6. A motion transmitting overtravel mechanism comprising a base, a substantially cylindrical operating member rotatably mounted upon said base, a pair of stop members carried by said operating member and arranged to engage said base to limit rotation of said operating member between two predetermined angularly displaced positions, an actuating member pivotally mounted upon said base for movement between two angularly spaced limiting positions and about an axis substantially perpendicular to the aXis of rotation of said operating member, a releasable overriding clutch connection between the surface of said cylindrical operating member and a portion of said actuating lever offset from said pivotal axis longitudinally of said cylindrical operating member,

said clutch connection effecting movement of said actuating member between said limiting positions within the limits of rotation of said operating member and permitting overtravel of said operating member in both directions, and ad- -justable means for biasing said operating memher to a selectable normal position within said limits of rotation, thereby normally to dispose said actuating member in either of said limiting positions.

7. A motion transmitting overtravel mechanism comprising a base, a substantially cylindrical op-- erating member rotatably mounted upon said base, a pair of stop members carried by said operating member and arranged to engage said base to limit-*rotation of said operating member between two predetermined angularly displaced positions, an actuatin lever pivotally mounted upon said base for rotation between two angularly spaced limiting positions and about an axis substantially perpendicular to the axis of rotation of said operating member, a clutch arm attached to said actuating lever and extending from said pivotal axis in a direction substantially longitudinal of said cylindrical operating member, andv a spring-pressed ball and socket connection between said clutch arm and the cylindrical surface of said operating member, said operating member effecting movement of said actuating lever between said limiting positions within the limits of rotation of said operating member and said ball and socket connection permitting overtravel of said operating member with respect to said actuating lever in both directions.

8. A motion transmitting overtravel mechanism comprising a base, a substantially cylindrical operating member rotatably mounted upon said base and having a radially extending arm, a pair of stop members carried by said operating member and arranged to engage said base to limit rotation of said operating member between two predetermined angularly displaced positions, an actuating lever pivotally mounted upon said base for rota tion between two angularly spaced limiting positions and about an axis substantially perpendicular to the axis of rotation of said operating member, a clutch arm attached to said actuating lever and extending from said pivotal axis in a direction substantially longitudinal of said cylindrical operating member, a spring-pressed ball and socket connection between said clutch arm and the cylindrical surface of said operating member, said operating member ellecting movement of said actuating lever between said limiting positions within the limits of rotation of said operating member and said ball and socket connection permitting overtravel of said operating member with respect to said actuating lever in both directions, adjustable stop means for selectably determining the normal position of said operating member, and a G-shaped spring encircling said operating member and having its ends positioned normally to align said radially extending arm and said adjustable stop.

ROBERT W. GOFF