US3175423A

US3175423A - Switch actuator

Info

Publication number: US3175423A
Application number: US195239A
Authority: US
Inventors: Charles J Adams
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1962-05-16
Filing date: 1962-05-16
Publication date: 1965-03-30
Anticipated expiration: 1982-03-30

Description

March 30, 1965 c. J. ADAMS 3,12%,423

SWITCH ACTUATOR Filed May 16, 1962 2 Sheets-Sheet 1 INVENTOR. CHARLES J ADA/W8,

- ATTORNE).

March 30, 1965 c. J. ADAMS 3,175,423

SWITCH ACTUATOR Filed May 16, 1962 2 Sheets-Sheet I2 INVENTOR. CHARLES J ADAMS,

BY 714- M ATTORNEY.

United States Patent 3,175,423 SWITCH ACTUATOR Charles J. Adams, Bloomington, llL, assiguor to General Electric Company, a corporation of New York Filed May 16, 1962, Ser. No. 195,239 16 Claims. (Cl. 74-568) This invention relates to limit switches and particularly to actuating mechanisms for switches wherein a switchactuating member is moved in accordance with rotation of a rotatable input shaft.

Limit switches of the rotary type have heretofore included switch-actuating mechanism comprised of a switch actuating member and means for moving the actuating member about an axis in accordance with rotation of an input shaft to effect actuation of one or more switches.

In previous limit switches of this type ditficulties have been encountered in providing an adequate speed reduction between the input shaft and the switch actuating member so that the member will move a small angular distance for a large number of revolutions of the input shaft. Also, it is very desirable that provision be made for effecting a quick reset of the actuated switch in response to a reversal in the direction of rotation of the input shaft. In other words, after the actuating member has moved in one direction to effect actuation of a switch, it is highly desirable that the actuating member be quickly moved in the reverse direction to reset the switch in re sponse to a reversal in the rotational direction of the input shaft. It is also desirable that provision be made for adjusting the angular position of the switch actuating member about its axis of rotation to permit variation of the point at which the switch is actuated in response to rotation of the input shaft, and in mechanisms which include a number of switch actuating members, difficulties have been encountered in effecting angular adjustment of a selected actuating member without disturbing the angular positions of adjacent actuating members. In limit switches incorporating a number of switches, it is necessary that the switches be compactly arranged and yet be readily acccessible for replacement, repair, etc. Previous attempts at providing the above desirable features have in general been unsatisfactory in that they have resulted in the provision of complex switch actuating mechanisms having numerous parts necessitating wide spacing of the switches and resulting in bulky, expensive and, in most cases, ineffective switch devices.

It is therefore a primary object of the present invention to provide a novel and improved limit switch of inexpensive and compact design incorporatin a unique switch actuating mechanism having a plurality of separate speed reduction means between a rotatable input shaft and a switch actuating member.

It is another important object of the invention to provide a switch actuating mechanism including a rotatable input shaft and a switch actuating member movable through speed reducing means in response to rotation of the input shaft with novel and improved means for rapidly moving the switch actuating member in the reverse direction to reset an actuated switch in response to a reversal in the rotational direction of the input shaft.

It is a further object of the invention to provide a rotary limit switch including a plurality of switch actuating members movable in response to rotation of an input shaft with novel and improved means for permitting angular adjustment of a selected one of the switch actuating members about its axis of movement to vary the point of switchactuation without displacing an adjacent switch actuating member about its axis of movement.

It is a still further object of the invention to provide a rotary limit switch of inexpensive and compact construc- "ice m at.

tion including a plurality of switches arranged in a novel manner about a central axis and having a plurality of separate speed reduction means intermediate a plurality of switch actuating members and a rotatable input shaft and having means for effecting quick resetting of actuated switches.

in carrying out the invention in one preferred form there is provided a rotary limit switch including a plurality of switch actuating members movable in circular paths about a common central axis in response to rotation of an input shaft for actuating a plurality of switches spaced anguiarly about the central axis. The actuating members are driven through speed reduction means including a worm on the input shaft meshing with a worm gear freely rotatable about a hollow shaft which carries the actuating members in axially spaced relation and which is freely rotatable about a fixed central shaft extending along the central axis. Additional speed reduction is afforded by a planetary gear system including a pair of planet gears which are mounted by the worm gear for rotation about the central axis and also about their own axes in responses to rotation of the worm gear and which mesh respectively with a fixed sun gear and a gear formed on the hollow shaft. A clutch ring is interposed between the worm gear and the hollow shaft and the arrangement is such that the hollow shaft and the actuating members thereon rotate in the same direction as the worm gear and at an angular velocity which is a fraction of that of the worm gear.

The described arrangement provides a desirable switch resetting feature wherein an actuated switch may be rapidly reset in response to a reversal in the direction of rotation of the input shaft. The clutch disc causes the hollow shaft to be retarded by the forward limit of the planetary gearing rather than be driven by the back limit of the backlash thereof. As a result, when the input shaft has completed a number of revolutions and is reversed, all of the planetary gearing backlash is taken up by the clutch disc which causes the hollow shaft to rotate at the same angular velocity as the Worm gear during backlash take up. Therefore, during backlash take up the actuating member is rotated comparatively rapidly for a certain angular distance to provide a quick reset of the previously actuated switch.

The actuating members are supported by mounting discs which are releasably secured to the hollow shaft and which have teeth formed thereon. In order to permit adjustment of the actuating members angularly about the central axis a plurality of spring-biased, rotatably mounted adjusting pinions are spaced angularly about the central axis and are normally biased out of engagement with the teeth of the associated mounting discs. Each adjusting pinion may be depressed into meshing engagement with the teeth of its associated mounting disc and rotated by means of a conventional screw driver to rotate the disc and the actuating member thereon to a desired angular position. A plurality of washers are keyed to the hollow shaft between adjacent ones of the mounting discs so that adjustment of one mounting disc may be effected without causing angular displacement of an adjacent mounting disc.

Other objects and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawings in which:

PEG. 1 is a view in top plan of the rotary limit switch with parts broken away;

FIG. 2 is a view in section taken along the line 2-2 of FIG. 1;

FIG. 3 is a view in elevation of the switch with parts in section showing four switches within the housing;

FIG. 4 is an exploded view of the switch actuating mechanism with parts shown in perspective;

FIG. 5 is a view in elevation with parts shown in section of the adjusting mechanism for adjusting a switch actuating member; and

FIG. 6 is a view taken along the line 6-6 of FIG. 5.

Referring now to the drawings there is illustrated in FIGS. 1 and 2 a rotary limit switch constructed according to the teachings of the present invention and including a housing 10 containing one or more switch actuating members in the form of rollers 11 mounted for movement in circular paths about the central vertical axis of the device in response to rotation of an input shaft 12 for actuating one or more switches 13 each having an actuating element 14 engageable with the periphery of the associated actuating member. While two switches 13 are shown in FIG. 1, any number of switches 13 from one to four may be provided as will appear hereinafter.

The housing It) is of generally square cross section taken in a vertical plane as viewed in FIG. 1 and includes a base 15 which detachably mounts a cover 15a shown in FIG. 3. The input shaft 12 extends through a side wall 16 of the base 15 along an axis which is generally perpendicular to the central vertical axis and which is at one side of the central axis. The input shaft 12 is supported for rotation by spaced bearings 17 on the housing base 14 and includes a part 18 located externally of the housing to be rotated in accordance with movement of a device the limit of movement of which is to be established by operation of one of the switches 13. The housing 1t may be mounted in any suitable manner to a support in the proper orientation to permit rotation of the shaft 12.

To provide a driving connection and also an initial speed reduction between the shaft 12 and the members 11, the shaft 12 includes a part 19 located within the housing having formed thereon a worm 21? which meshes with a worm gear 21 loosely surrounding a hollow shaft 22 which carries the members 11 in a manner described hereinafter. The shaft 22 in turn loosely surrounds a central shaft 23 which is fixed to the bottom Wall of the base 15 and which extends upwardly therefrom along the central vertical axis of the device. The hollow shaft 22 is rotatable relative to the fixed shaft 23 and is retained upon the shaft 23 by means of a retaining ring 26 located Within an annular groove of the shaft 23 and overlying shaft 22. By suitable arrangement of the worm 2t) and worm gear 21 a number of different speed reductions may be obtained.

In order to support the members 11 a plurality of axially-aligned discs 30 loosely surround the hollow shaft 22 and are spaced from one another by washers 31 located between adjacent ones of the discs 31 and keyed to the hollow shaft 22 as best shown in FIGS. 2 and 4. Each of the discs 30 includes a vertical extension 32 which rotatably supports a member 11 such that the members 11 are spaced angularly with respect to one another about the axis of the central shaft 23 thereby permitting a desired sequence of operation of the associated switches. It can be appreciated that the number of discs 30, members 11 and switches 13 employed may vary depending upon the particular application. Each of the discs 30 is formed with an annular ring 33 having gear teeth 34 adapted to mesh with an adjusting means 35 described hereinafter, and the discs 31) are retained in operative positions on the shaft 22 by means of a clamping plate 36 (FIGS. 1 and 2) engaging the upper surface of the upper one of the discs 30 and secured to the shaft 22 by screws 37.

In accord with the invention an additional speed reduction is provided by means of a planetary gearing system represented generally by the numeral 40 and operatively connected between the Worm gear 21 and the shaft 22 as best shown in FIG. 4. The planetary gearing system 40 comprises a pair of

planet gears

41 and 42 which are attached to each other and which are mounted by a stub shaft 43 depending from the lower surface of the worm gear 21 so as to be rotatable as a unit about the stub shaft 43 and also rotatable about the axis of the shaft 23 in response to rotation of the worm gear 21. The planet gears 41 and 42 mesh respectively with a gear 44 fixed on the shaft 22 and with a sun gear 45 coaxial with the gear 44 and fixed on the upper surface 24 of the base 15. The planet gears 41 and 42 and the gears 44 and 45 are surrounded by an annular wall 46 extending upwardly from the bottom surface 24 of the base 15 and coaxial with the central axis of the device. The worm gear 21 rests upon the upper surface of the annular wall 46 so that the planetary gearing system is completely enclosed by means of the wall 46 and the worm gear 21 to prevent the entry of foreign matter thereinto.

The invention also provides an additional driving connection between the shaft 22 and the worm gear 21 in the form of clutch means 5%? shown in FIGS. 2 and 4 positioned between the worm gear 21 and an annular ring 51 formed integrally on the shaft 22 or otherwise attached thereto. One of the

parts

50 and 51 is preferably of resilient construction and in the preferred embodiment the clutch means consists of a ring formed of a suitable resilient material surrounding the shaft 22 and is of relatively large area to assure a good frictional contact with the worm gear 21 and the ring 51. The clutch ring 50 may be of any suitable construction and as one example, the clutch ring 50 consists of a Velmoid packing soaked in Oild ag at an elevated temperature such as 70 C. for several hours. As an alternative construction, the clutch ring 51) may be eliminated and the space between the worm gear 21 and the ring 51 reduced to retain by capillary action a viscous lubricant serving the same function as the replaced clutch ring 50.

If the planetary gearing system 40 were omitted, then rotation of the input shaft 12 would effect rotation of the ring 51 and therefore the shaft 22 through the worm 20 and worm gear 21 at the same angular velocity as that of the worm gear 21 through the agency of the clutch ring 51). However, the planetary gearing system 40 serves to limit the angular velocity of the shaft 22 and the ring 51 to a fraction of that of the Worm gear 21 and the clutch ring- 5%) slips over the ring 51. It can be appreciated that var ious angular velocities of the shaft 22 may be obtained by suitable selection of the number of gear teeth on the gears of the planetary gearing system. A very satisfactory limit switch has been constructed including a planetary gearing system arranged as follows:

Planet gear 41 teeth 14 Planet gear 42 do- 16 Gear 44 do 32 Sun gear 45 do- 3 Distance between center line of gear 45 and center line of

gears

41 and 42 using 32 diametral pitch gears inch With the above-described gear ratios and center spaming, it can be demonstrated that the shaft 22, and tiiere-' fore the switch actuating members 11, are caused to ro-- tate in the same direction as the worm gear 21 at an angular velocity which is approximately .18 times that of the worm gear 21. By deliberately mismatching certain of the gear combinations advantages in operation may be realized. For example, using the same 7 inch spacing between the center lines of

gears

41 and 42 and gear 45 and using 32 diametral pitch gears, the gears 41 and 44 may have respectively fifteen and thirty teeth and the

gears

42 and 45 sixteen and thirty teeth, which results in an angular velocity of the shaft 22 which is ap proximately .0625 that of the worm gear 21. In this last, example the gears 41 and 44 are intended to operate with a center distance of inch instead of the inch spacing employed. This provides a mismatch with in-. creased backlash between the gears 41 and 44 which is very desirable as will presently appear.

In order to permit angular adjustment of the members 11 about the axis of the shaft 23 to thereby vary the point.

at which the switches will be actuated, the present invention provides a plurality of adjusting means 35 each arranged for association with a separate one of the discs 30. Two adjusting means 35 are illustrated in FIG. 1 and each of such adjusting means is of similar construction. As best shown in FIG. 5 the adjusting means includes an actuating member 55 having a slotted head 56 for receiving a conventional tool, such as a screw driver, and a restricted body portion 57 extending through an extension 58 of a plate 58' extending beneath the casing of the associated switch 13. A pinion 59 is secured to the body portion 57 directly beneath the slotted head 56, and a retaining ring 63 is secured to the body portion 5'7 beneath the extension 58 of plate 58 to limit upward movement of the actuating member 55. The tip of the body portion 57 engages the free end of a resilient member er shown in the form of a leaf spring attached to the under side of the plate 58'. The spring 61 normally biases the actuating member 55 to its uppermost position wherein the retaining ring 60 engages the undersurface of the extension 58, and the pinion 59 is disengaged from the teeth 34 formed on the associated disc 39.

If it is desired to effect angular adjustment of the member 11 carried by the associated disc 39, an operator loosens the screws 37, inserts a tool, such as a screw driver, into the slot formed in the head 56 and depresses the actuating element 55 to cause meshing of the pinion 59 and the teeth 34 on disc 3t Downward movement of pinion 59 is limited by engagement thereof with the upper surface of extension 58 which occurs when pinion 59 is in meshing engagement with teeth 34. The actuating device 55 is then rotated which results in rotation of pinion S9 and disc 30 to effect angular adjustment of the associated member 11 to a desired position. After the adjustment is made, the screw driver is released from the head 56 with the result that the device 55 is elevated to its normal position under the action of the spring at, and the screws 37 are tightened to clamp the discs 30 in operative positions. Since the washers 31 between adjacent discs 30 are keyed to shaft 22, angular adjustment of one disc 30 as above described does not disturb the angular position of an adjacent disc 30.

The switches 13 may be of any suitable construction, such as snap switches, and in the illustrated embodiment each switch has an operating element 63 depending therefrom and reciprocable in vertical directions as viewed in FIG. 5. When the element 63 is fully extended as shown, it is slightly spaced from or lightly engages a lower arm 64 of the actuating element 14 which is generally L-shaped and which includes an upwardly extending arm 65 pivotally mounted by spaced brackets 65 formed on the plate 58' as best shown in FIG. 6. A projection 67 is lanced out of the arm 65 to be engaged by the cam 11 and, when so engaged, results in pivoting of the element 14 and upward movement of the arm 64 which elevates the element 63 to operate the switch. The mounting arrangement of the switches 13 is shown in FIG. 3 wherein four switches 13 are illustrated spaced angularly about the central axis and also displaced axially of the central axis to form a spiral about the central axis. The switches are each supported on spaced upstanding members 68 containing threaded openings 65 to receive screws 76 which pass through the switch casings. The pairs of members 68 are of dilferent heights to provide the axial spacing of the switches and are symmetrically spaced angularly about the central axis of the shaft 23. One set of members 68, at the left hand side of FIG. 1, projects from the bearings 17 whereas the opposite set projects a shorter distance from a raised portion '71 of the bottom wall of the base. The remaining opposed sets of members 68 project different distances from

parts

72 and 73 which extend upwardly from the bottom wall of the base.

In operation, rotation of the input shaft 12 and the worm 20 imparts rotation to the worm gear 21 which tends to rotate the disc 51 and therefore the shaft 22 and members 11 at the same angular velocity as the worm gear 21 through the agency of the clutch 56. However, the planetary gearing system comprised of the planet gears 41 and 42, the gear 44, and the sun gear 45 causes a reduction in the angular velocity of shaft 22 so that the clutch slips over the disc 51. After a number of revolutions of the input shaft 12, a selected one of the members 11 will be rotated to a position wherein it engages the projection 67 of the actuating element 14 of the associated switch 13 to operate such switch. The clutch disc 5%) causes shaft 22 to be retarded by the forward limit of the planetary gearing rather than be driven by the back limit of the backlash thereof. Consequently, in the event that the rotational direction of the input shaft 12 is reversed subsequent to actuation of a switch, all of the planetary gearing backlash is taken up by the clutch ring 5t which causes the ring 51 and the shaft 22 to rotate at the same angular velocity as the worm gear 21 dur ing such backlash take up. This arrangement results in a very desirable quick resetting action since the amount of reversed rotation of shaft 12 necessary to reset the actuated switch is considerably less due to the action of the clutch ring 50.

lthough the invention has been described with reference to certain specific embodiments thereof, numerous modifications are possible, and it is desired to cover all modifications falling within the spirit and scope of the in vention.

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

1. In a rotary switch actuator, a member rotatable about an axis for actuating a switch, a rotatable input shaft, and speed reduction gearing operatively connected between the member and the input shaft, said gearing including a worm on the input shaft, a worm gear sur rounding said member meshing with the worm and rotatable relative to said member, and planetary gearing operatively connected between the worm gear and the member for rotating said member relative to said worm gear at an angular velocity less than that of said worm gear and friction clutch means between the worm gear and the member to rotate the member at essentially the same angular velocity as the worm gear upon a reversal in the direction of rotation of the input shaft and during the take up of backlash in the planetary gearing.

2. In a rotary switch actuator, a member rotatable about an axis for actuating a switch, a rotatable input shaft, and speed reduction gearing operatively connected between the member and the input shaft, said gearing including a Worm on the input shaft, a worm gear meshing with the worm and rotatable relative to said member, and planetary gearing operatively connected between the worm gear and the member for rotating said member at an angular velocity less than that of said worm gear; a housing operatively mounting all of said elements, and an annular wall extending from said housing surrounding said planetary gearing, said worm gear resting on the outer surface of said wall to completely enclose the planetary gearing.

3. In a rotary switch actuator, a member rotatable about an axis for actuating a switch, a rotatable input shaft, and speed reduction gearing operatively connected between the member and the input shaft, said gearing including a worm on said input shaft, a worm gear loosely surrounding said member meshing with the worm, planetary gearing for rotating said member at an angular velocity less than that of the worm gear including a sun gear fixed on said axis, a third gear fixed on said member and rotatable about said axis relative to the sun gear, and a pair of planet gears rotatable in accordance with said worm gear respectively about said sun gear and said third gear and also about their own axes; and friction clutch means betweenthe worm gear and the member to rotate the member at essentially the same angular velocity as the worm gear upon a reversal in the direction of rotation of the input shaft and during the take up of backlash in the planetary gearing.

4. In a rotary switch actuator, a member rotatable about an axis for actuating a switch, a rotatable input shaft, and speed reduction gearing operatively connected between the member and the input shaft, said gearing including a worm on the input shaft, a worm gear meshing with the worm, and planetary gearing operatively connected between the worm gear and the member for rotating said member at an angular velocity less than that of said worm gear, an adjusting gear operatively connected to said member, and a manually depressible and rotatable pinion normally biased out of engagement with said adjusting gear and depressible into meshing engagement therewith to permit rotation of the adjusting gear and said member in response to rotation of the pinion independently of said worm gear.

5. In a rotary switch actuator, a first member rotatable about an axis for actuating a switch, a second member rotatable about an axis for controlling rotation of said first member, planetary gearing operatively connected between the second member and the first member for rotating the first member at an angular velocity less than that of the second member, said' gearing including a fixed sun gear, a second gear rotatable relative to said sun gear, a pair of planet gears rotatable as a unit in accordance with rotation of said second member about said sun gear and said second gear respectively, said first member being operatively connected to said second gear to be driven thereby, and means providing a friction clutch between the second member and the first member to rotate the first member at essentially the same angular velocity as the second member upon a reversal in the direction of rotation of the second member and during the take up of backlash in the planetary gearing.

6. In a rotary switch actuator, a first member rotatable about an axis for actuating a switch, a second member rotatable about an axis for controlling rotation of said first member, planetary gearing operatively connected between the second member and the first member for rotating the first member at an angular velocity less than that of the second member, and means providing a friction clutch between the second member and the first member to rotate the first member at essentially the same angular velocity as the second member upon a reversal in the direction of rotation of the second member and during the take up of backlash in the planetary gearing, an ad justing gear operatively connected to said first member, and a manually depressible and rotatable pinion normally biased out of engagement with said adjusting gear and depressible into meshing engagement therewith to permit rotation of the adjusting gear and the first member in response to rotation of the pinion independently of said second member. I

7. In a rotary switch actuator, a housing, support means rotatably mounted by the housing on a central axis, a first member carried by the support means for rotation therewith about the central axis for actuating a switch, a second member rotatable about the central axis relative to said support means for controlling rotation of the support means, planetary gearing operatively connected between the second member and the support means for rotating the support means at an angular velocity less than that of the second member, and an annular wall extend-ing from said housing surrounding said planetary gearing, said second member resting on the outer surface of said wall to completely enclose the planetary gearing.

8. In a rotary switch actuator, a housing, an input shaft journalled by the housing for rotation in either of two opposite directions and formed with a worm, a central shaft fixed to the base of said housing and extending generally perpendicular to said input shaft, a hollow member loosely surrounding said central shaft for rotation with respect thereto, a worm gear loosely surrounding said hollow member and meshing with said worm for rotation relative to said hollow member in response to rotation of said input shaft, planetary gearing including a sun gear fixed to said base in coaxial relation with said central shaft, said hollow member, and said worm gear, an auxiliary gear fixed to said hollow member, and a pair of planet gears mounted for rotation with said worm gear respectively about said sun gear and said auxiliary gear and also about their own axes; and a switch actuating member carried by said hollow member for rotation therewith.

9. In a rotary switch actuator, a housing, an input shaft journalled by the housing for rotation in either of two opposite directions and formed with a worm, a central shaft fixed to the base of said housing and extending generally perpendicular to said input shaft, a hollow member loosely surrounding said central shaft for rotation with respect thereto, a worm gear loosely surrounding said hollow member and meshing with said worm for rotation relative to said hollow member in response to rotation of said input shaft, planetary gearing including a sun gear fixed to said base in coaxial relation with said central shaft, said hollow member, and said worm gear, an auxiliary gear fixed to said hollow member, and a pair of planet gears mounted for rotation with said worm gear respectively about said sun gear and said auxiliary gear and also about their own axes; a switch actuating member carried by said hollow member for rotation therewith, and an annular wall extending from said base surrounding said planetary gearing, said worm gear resting on the outer surface of said wall to completely enclose the planetary gearing.

10. In a rotary switch actuator, a housing, an input shaft journalled by the housing for rotation in either of two opposite directions and formed with a worm, a central shaft fixed to the base of said housing and extending generally perpendicular to said input shaft, a hollow member loosely surrounding said central shaft for rotation with respect thereto, a worm gear loosely surrounding said hollow member and meshing with said worm for rotation relative to said hollow member in response to rotation of said input shaft, planetary gearing including a sun gear fixed to said base in coaxial relation with said central shaft, said hollow member, and said worm gear, an auxiliary gear fixed to said hollow member, and a pair of planet gears mounted for rotation with said worm gear respectively about said sun gear and said auxiliary gear and also about their own axes; a plurality of axially spaced discs loosely surrounding said hollow member, a plurality of switch actuating members each mounted by a separate one of said discs, means releasably clamping said discs to said hollow member for rotation therewith, a plurality of washers keyed to said hollow member between adjacent ones of said discs, a plurality of adjusting gears each fixed on a separate one of said discs, and a plurality of independent adjusting means each consisting of a rotatable spring-biased pinion normally disengaged from an associated adjusting gear and depressible into meshing engagement therewith whereupon rotation of the pinion effects rotation of the associated disc and switch actuating member when the means clamping the discs is released from said hollow member.

11. In a rotary switch actuator, a housing, an input shaft journalled by the housing for rotation in either of two opposite directions and formed with a worm, a central shaft fixed to the base of said housing and extending generally perpendicular to said input shaft, a hollow member loosely surrounding said central shaft for rotation with respect thereto, a worm gear loosely surrounding said hollow member and meshing with said worm for rotation relative to said hollow member in response to rotation of said input shaft, planetary gearing including a sun gear fixed to said base in coaxial relation with said central shaft, said hollow member, and said worm gear, an auxiliary gear fixed to said hollow member, and a pair of planet gears mounted for rotation with said worm gear respectively about said sun gear and said auxiliary gear and also about their own axes; a switch actuating member carried by said hollow member for rotation therewith, and means providing a friction clutch between said worm gear and said [hollow member which tends to rotate said hollow member at the same angular velocity as that of said worm gear, said planetary gearing operating to limit the angular velocity of said hollow member to a fraction of that of said worm gear, said means providing a friction clutch being effective to rotate said hollow member at the same angular velocity as that of said worm gear upon a reversal in the direction of rotation of said input shaft and during the take up of backlash in the planetary gearing.

12. In a rotary switch actuator, a housing, an input shaft journalled by the housing for rotation in either of two opposite directions and formed with a worm, a central shaft fixed to the base of said housing and extending generally perpendicular to said input shaft, a hollow member loosely surrounding said central shaft for rotation with respect thereto, a Worm gear loosely surrounding said hollow member and meshing with said worm for for rotation relative to said hollow member in response to rotation of said input shaft, planetary gearing including a sun gear fixed to said base in coaxial relation with said central shaft, said hollow member, and said worm gear, an auxiliary gear fixed to said hollow member, and a pair of planet gears mounted for rotation with said worm gear respectively about said sun gear and said auxiliary gear and also about their own axes; a plurality of axially spaced discs loosely surrounding said hollow member, a plurality of switch actuating members each mounted by a separate one of said discs, means releasably clamping said discs to said hollow member for rotation therewith, a plurality of washers keyed to said hollow member between adjacent ones of said discs, a plurality of adjusting gears each fixed on a separate one of said discs, a plurality of independent adjusting means each consisting of a rotatable spring-biased pinion normally disengaged from an associated adjusting gear and depressible into meshing engagement therewith with whereupon rotation of the pinion effects rotation of the associated disc and switch actuating member when the means clamping the discs is released from said hollow member, and means providing a friction clutch betwen said worm gear and said hollow member which tends to rotate said hollow member at the same angular velocity as that of said worm gear, said planetary gearing operating to limit the angular velocity of said hollow member to a fraction of that of said worm gear, said means providing a friction clutch being efiective to rotate said hollow member at the same angular velocity as that of said worm gear upon a reversal in the direction of rotation of said input shaft and during the take up of backlash in the planetary gearing.

13. In a rotary switch actuator, a housing, an input shaft journalled by the housing for rotation in either of two opposite directions and formed with a worm, a central shaft fixed to the base of said housing and extending generally perpendicular to said input shaft, a hollow member loosely surrounding said central shaft for rotation with respect thereto, a worm gear loosely surrounding said hollow member and meshing with said worm for rotation relative to said hollow member in response to rotation of said input shaft, planetary gearing including a sun gear fixed to said base in coaxial relation with said central shaft, said hollow member, and said worm gear, an auxiliary gear fixed to said hollow member, and a pair of planet gears mounted for rotation with said worm gear respectively about said sun gear and said auxiliary gear and also about their own axes; a plurality of axially spaced discs loosely surrounding said hollow member, a plurality of switch actuating members each mounted by a separate one of said discs, means releasably clamping said discs to said hollow member for rotation therewith, a plurality of washers keyed to said hollow member between adjacent ones of said discs, a plurality of adjusting gears each fixed on a separate one of said discs, and a plurality of independent adjusting means each consisting of a rotatable spring-biased pinion normally disengaged from an associated adjusting gear and depressible into meshing engagement therewith whereupon rotation of the pinion effects rotation of the associated disc and switch actuating member when the means for clamping the discs is released from said hollow member, means providing a friction clutch between said worm gear and said hollow member which tends to rotate said hollow member at the same angular velocity as that of said worm gear, said planetary gearing operating to limit the angular velocity of said hollow member to a fraction of that of said worm gear, said means providing a friction clutch being effective to rotate said hollow member at the same angular velocity as that of said worm gear upon a reversal in the direction of rotation of said input shaft and during the take up of backlash in the planetary gearing, and an annular wall extending from said base surrounding said planetary gearing, said worm gear resting on the outer surface of said wall to completely enclose the planetary gearing.

14. In a rotary limit switch, a housing, a plurality of switches mounted in the housing spaced angularly about a central axis of the housing and also displaced from one another axially of the central axis, support means rotatably mounted by the housing on said central axi a plurality of first members carried by the support means for rotation therewith about the central axis each for actuating a separate one of said switches, a second member surrounding said support means and. rotatable relative to said support means about the central axis for controlling rotation of said support means, said first members being located on one side of said second member, and planetary gearing located entirely on the other side of said second member and operatively connected between the second member and the support means for rotating the support means at an angular velocity less than that of the second member, said planetary gearing including gears mounted coaxially on said central axis.

15. In a rotary limit switch, a housing, a plurality of switches mounted in the housing spaced angularly about a central axis of the housing and also displaced from one another axially of the central axis, support means rotatably mounted by the housing on said central axis, a plurality of first members carried by the support means for rotation therewith about the central axis each for actuating a separate one of said switches, a second member surrounding said support means and. rotatable relative to said support means about the central axis for controlling rotation of said support means, said first members being located on one side of said second memher, and planetary gearing located entirely on the other side of said second member and operatively connected between the second member and the support means for rotating the support means at an angular velocity less than that of the second member, and means providing a friction clutch between the second member and the support means to rotate the support means at essentially the same angular velocity as the second. member upon a reversal in the direction of rotation of the second member and during the take up of backlash in the planetary gearing.

16. In a rotary limit switch, a housing, a plurality of switches mounted in the housing spaced angularly about a central axis of the housing and also displaced from one another axially of the central axis, support means rotatably mounted by the housing on said central axis, a

35.1 plurality of first members carried by the support means for rotation therewith about the central axis each for actuating a separate one of said switches, a second member rotatable relative to said support means about the central axis for controlling rotation of said support means, and planetary gearing operatively connected between the second member and the support means for rotating the support means at an angular velocity less than that of the second member, and means providing a friction clutch between the second member and the support means to rotate the support means at essentially the same angular velocity as the second member upon a reversal in the direction of rotation of the second member and during the take-up of backlash in the planetary gearing, and an annular wall extending from said housing References Cited by the Examiner UNITED STATES PATENTS 694,370 3/02 Gill 74-802 1,788,602 1/31 Sutton et al. 74802 2,594,911 4/52 Golf 74568 2,651,530 9/53 Blydenburgn 6430 BROUGHTON G. DURHAM, Primary Examiner.

Claims

14. IN A ROTARY LIMIT SWITCH, A HOUSING, A PLURALITY OF SWITCHES MOUNTED IN THE HOUSING SPACED ANGULARLY ABOUT A CENTRAL AXIS OF THE HOUSING AN ALSO DISPLACED ABOUT ONE ANOTHER AXIALLY OF THE CENTRAL AXIS, SUPPORT MEANS ROTATABLY MOUNTED BY THE HOUSING ON SAID CENTRAL AXIS, A PLURALITY OF FIRST MEMBERS CARRIED BY THE SUPPORT MEANS FOR ROTATION THEREWITH ABOUT THE CENTRAL AXIS EACH FOR ACTUATING A SEPARATE ONE OF SAID SWITCHES, A SECOND MEMBER SURROUNDING SAID SUPPORT MEANS AND ROTATABLE RELATIVE TO SAID SUPPORT MEANS ABOUT THE CENTRAL AXIS FOR CONTROLLING ROTATION OF SAID SUPPORT MEANS, SAID FIRST MEMBERS BEING LOCATED ON ONE SIDE OF SAID SECOND MEMBER, AND PLANETARY GEARING LOCATED ENTIRELY ON THE OTHER SIDE OF SAID SECOND MEMBER AND OPERATIVELY CONNECTED BETWEEN THE SECOND MEMBER AND THE SUPPORT MEANS FOR ROTATING THE SUPPORT MEANS AT AN ANGULAR VELOCITY LESS THAN THAT OF THE SECOND MEMBER, SAID PLANETARY GEARING INCLUDING GEARS MOUNTED COAXIALLY ON SAID CENTRAL AXIS.