US3715530A

US3715530A - Actuating device

Info

Publication number: US3715530A
Application number: US00174453A
Authority: US
Inventors: T Dalton
Original assignee: Westran Corp
Current assignee: Westran Corp
Priority date: 1971-08-24
Filing date: 1971-08-24
Publication date: 1973-02-06
Anticipated expiration: 1990-02-06

Abstract

A device for actuating a pair of spaced limit switches in which an actuating member is reciprocably mounted for movement between the limit switches. The device comprises a rotatably mounted shaft having a wire wound around a selected length of the shaft and defining a helical path. The opposite ends of the wire are fixed to the shafts in such a manner that when a portion of the actuating member is disposed in the helical path, that is, between any two adjacent turns of the wire, the adjacent sides of each of the remaining successive turns of the wire are normally in abutment. As the shaft is rotated in opposite directions, the wire reciprocally drives the actuating member between the limit switches.

Description

United States Patent [1 1 Dalton 1 Feb. 6, 1973 541 ACTUATING DEVICE 3,427,546 2/1969 Peartet al. ..338/180 [75] Inventor: Thomas B. Dalton, Muskegon, Primary Examiner Herman l Hohauser Attorney-Robert C. Hauke et al. [73] Assignee: Westram Corporation, Muskegon, I [57] ABSTRACT Mich.

[221 Filed: 24 1971 device for actuatinga pair of spaced limit switches in which an actuating member 18 reciprocably [21] Appl. No.: 174,453 mounted for movement between the limit switches.

The device comprises a rotatably mounted shaft hav- Related Apphcat'on Data ing a wire wound around a selected length of the shaft [63] Continuation-in-part of Ser. No. 4,883, Jan. 22, definmg a hehcal path] The opposlte ends of the 1970, abandoned wire are fixed to the shafts m such a manner that when a portion of the actuating member is disposed in the 52 vs. C]. ..200/47, 74/458, 74/4247 Path that. W any adjacent "F. of the wlre, the ad acent sides of each of the remaining [51] Int. Cl.f ..H0lh 3/lo Successive turns of the wire are normally in abutment [58] held 0 Search As the shaft is rotated in opposite directions, the wire 200/47; 338/180 1 reciprocally drives the actuating member between the limit switches. [56] References Cited UNITED STATES PATENTS Holmes ..74/424.7

8 Claims, 8 Drawing Figures PATENIEDFEB 61973 3.715.530

Ill/Ill!!! INVENTOR.

THOMAS B. DALTON ACTUATING DEVICE CROSS REFERENCE TO RELATED APPLICATION The present application is a continuation-in-part of co-pending U. S. Pat. application Ser. No. 4,883, filed Jan. 22, 1970, now abandoned.

BACKGROUND OF THE INVENTION I. Field of the Invention The present invention relates to actuating devices and is particularly applicable to such devices having a rotating shaft which reciprocally drives an actuating member to alternately actuate a pair of spaced limit switches.

II. Background of the Invention Heretofore, such actuating devices have taken the form of a pair of electrical limit switches which are adapted to be actuated by means of an actuating member which is reciprocally mounted between the two switches. The actuating member usually comprises a nut disposed intermediate the limit switches and adapted to travel axially along a rotating threaded shaft. Although such limit switches have functioned in a satisfactory manner, theyare characterized by certain disadvantages which the present invention overcomes. The threaded shaft of previous devices of course has a fixed number of turns per inch with the number depending upon the desired application. To modify the control requires in many cases replacement of the shaft. Such shafts are relatively expensive to manufacture as the grooves defined by each successive turn of the threads must be relatively deep to insure proper retention of the actuating member. If control of the actuating member within close tolerances is required, the shaft must have a greater number of threads per inch and this increases the cost of the manufacture of such shafts.

Such shafts also must be completely replaced in the event of any damage during operation and thus the cost of maintaining such devices represents another disadvantage in their use.

It is therefore desirable to provide an actuating device of the type hereinbefore described in which the actuating member is driven by a shaft selectively rotated in opposite directions, but which is of a simple and inexpensive construction.

SUMMARY OF THE PRESENT INVENTION The present invention which will be described subsequently in greater detail comprises a rotatable shaft having a wire wound around a selected length of the shaft with adjacent sides of each successive turn of the wire being normally in abutment but being axially separable to define a helical path to receive an actuating member as the shaft is rotated to alternately engage and disengage a pair of spaced limit switches. In the preferred embodiment, the wire is substantially rectangular in cross section and has a radial depth which substantially exceeds its axial thickness. The wire is wound around the shaft on its narrow edges such that the depth of the wire defines the depth of the helical path. This not only insures that there will be sufficient depth formed by the wire to securely retain the actuating member, but it also provides a device in which because of the relatively large number of turns per inch a quite accurate actuating device can be inexpensively achieved. Suitable clamping means releasably attach the wire to the shaft to permit it to be readily installed on any shaft and to permit it to be easily replaced in the event of damage to the wire during use.

It is therefore an object of the present invention to provide an improved means for actuating limit switches which is extremely accurate, simple in construction and inexpensive to manufacture.

It is also an object of the present invention to provide an improved means for actuating limit switches in which the driving portion thereof may be easily and inexpensively replaced.

Other objects, advantages and applications of the present invention will become apparent to those skilled in the art when the accompanying description of an example of the best mode contemplated for practicing the invention is read.

BRIEF DESCRIPTION OF THE DRAWING The description herein makes reference to the accompanying drawing wherein like reference numerals refer to like parts and in which:

FIG. 1 is perspective view of an actuating device constructed in accordance with the principles of the present invention;

FIG. 2 is a top plan view of the actuating device illustrated in FIG. 1;

FIG. 3 is a side elevational view of the actuating device illustrated in FIG. 1;

FIG. 4 is a transverse cross-sectional view of the actuating device taken along line 44 of FIG. 3;

FIG. 5 is a fragmentary perspective view of one example of the present invention prior to its installation on a shaft;

' FIG. 6 is a perspective view of the clamping means used in FIG. 1;

FIG. 7 is a fragmentary cross-sectional view taken along line 77 of FIG. 4; and

FIG. 8 is a fragmentary perspective view of a modification of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawing, there is illustrated an actuating device 10 of the rotary type having mounted thereon a pair of

conventional limit switches

12 and 14 adapted to control an electrical device (not shown) when the

limit switches

12 and 14 are actuated by an actuating member 16 which, in turn, is reciprocally driven by a rotating shaft 18. The shaft 18 could, for instance, be the output shaft of an electric motor and the actuating device 10 and the

limit switches

12 and 14 could be connected to the electric motor so that after rotation of the shaft 18 for a predetermined number of revolutions in one direction one of the limit switches would be engaged by the actuating member 16 to shut off the electric motor or to reverse the direction of rotation of the shaft for a predetermined number of revolutions.

The limit switches l2 and are preferably attached to the upper surface of one leg .20 of a generally L- shaped member 22. The other leg 24 of the L-shaped member 22 has an aperture 26 (FIG. 1) through which shaft 18 extends. Aperture 26 is sized to permit relative rotational movement between the shaft 18 and the leg 24. One end 28 of the shaft 18 extends outwardly from the device for connection to the rotary output of an electrical device, such as the aforementioned electric motor (not shown), whose operation it is desired to control and is adapted to rotate therewith, either directly or through suitable gearing means. The opposite end 32 of shaft 18 is rotatably supported by a suitable bearing 34 which, in turn, is fixedly mounted to the end of the leg by any suitable means, such as by welding or the like.

A flat wire 36 is wound around the outer periphery of the shaft 18 for a portion of the length of the shaft 18 and, as can be seen in FIGS. 5 and 7, the wire 36 is preferably rectangular in cross section having sides 38 with a radial depth substantially exceeding the axial thickness of the peripheral edge 40 of the wire 36. The

wire 36 is wound around the shaft 18 on its edges 40 such that the sides 38 of the wire 36 define the depth of the spacing between the successive turns of the wire 36. As can be best seen in FIGS. 1, 3,4 and 7, the adjacent sides 38 of each successive turn of the wire 36 are normally in abutment, except for that portion engaged by a pair of

flanges

42 and 44 of a U-shaped bracket 46 carried by the actuating member 16. The spacing formed by the separation between turns of the wire 36 as the

flanges

42 and 44 move along the shaft 18 defines a helical path 48 along the length of the shaft 18 and causes the actuating member 16 to be moved back and forth along the length of the shaft 18 as the shaft is rotated in opposite directions. The number of revolu- 'tions of the shaft 18 necessary to move the actuating member 16 any desired distance along the shaft 18 will depend .upon the number of turns of wire per inch on the shaft 18 and the total length of the wire 36. Thus, it can be seen that any selected control of the actuating member 16 may be obtained by using wires having various thicknesses of the edge 40 and various lengths so as to accommodate the particular application in which the limit switches-are to be utilized.

The opposite ends of the wire 36 are attached to the shaft 18 by means of a pair ofclamps 52 and 54 (FIG.

propriate pair of adjacent turns of thewire 36 and the

clamps

52 and 54 are so positioned on the shaft 18 that the remaining adjacent sides 38 of each adjacent turn of the wire 36 are in abutment. The screws 55 are then tightened to securely mount the

clamps

52, 54 and the wire 36 tothe shaft 18. Since the

clamps

52 and 54 and the wire 36 rotate with the shaft 18, the

flanges

42 and 44 and thus the actuating member- 16 will be reciprocally driven longitudinally along the shaft 18. As the shaft 18 is rotated, each adjacent side 38 of each successive turn of the wire 36 will be momentarily axially separated by the

flanges

42 and 44 as the same follow the helical path 48. In order to achieve this separation, each successive turn ofthe wire 36 moves axially a distance equal to the width of each

flange

42 and 44.

The

clamps

52 and 54 permit easy removal and replacement of the wire 36 in the event it fails during use or if a different control is desired. The wire 36 is preferably made from a spring steel, however, other materials having specific desired characteristics, such as wear or corrosion resistant materials, may be used depending upon the particular application.

The limit switches 12 and 14, respectively, have a pair of movable contacts 56 and 58, each of which is adapted to make and/or break an electrical circuit in their

respective limit switches

12 and 14 to generate an appropriate signal, which in turn controls the electrical device. The movable contacts 56 and 58 are positioned with respect to the upper surface of the leg 20 in such a manner that they extend over an elongated slot 60 in the leg 20. The slot 60 is disposed along an axis parallel to the longitudinal axis of the shaft 18 and functions to guide the movement of the actuating member 16 in a manner to be described hereafter.

The actuating member 16 is comprised of three components: an inverted T-shaped member 62, a rectangularly shaped member 63 carried at the top of the T- shaped member 62, and the U-shaped bracket member 46, all of which are coupled to each other by threaded screws 65. The upper leg of the member 62 extends through the slot 60 and is guided thereby as the actuating member 16 travels between the movable contacts 56 and 58. Each

flange

42 and 44 of the U-shaped member 46 has a semi-circular portion, one of which is shown at 66 in FIG. 4. The semi-circular portions 66 on each

flange

42 and 44 are adapted to extend into, at axially spaced points, the helical path 48 defined by the axially separated sides 38 of the wire 36 and are moved axially by the wire 36 as the shaft 18 turns in the same manner as a nut would move along a rotating threaded screw. As the shaft 18 is rotated in a clockwise direction as viewed in FIG. 4, the actuating member 16 will be driven by the wound wire 36 towards the movable contact 56, that is, to the left as viewed in FIG. 3. As the shaft 18 is rotated in the opposite direction, that is, counterclockwise as viewed in FIG. 4, the actuating member 16 will be moved toward the movable contact 58, that is, to the right as viewed in FIG. 3.

Thus, the wound spring wire 36 provides a helical path similar to the spiral groove on the threaded shafts of the previously described devices and functions in a similar manner to drive the actuating member 16 in either direction between the pair of spaced

limit switches

12 and 14 to alternately engage and actuate the limit switches.

In order to insure a smooth engagement of the actuating member 16 with each of the movable contacts 56 and 58, the opposite ends of the rectangularly shaped member 63 are beveled to form cam surfaces 70 and 72 (FIG. 2), which respectively engage the movable contacts 56 and 58 to displace the same. The limit switches 12 and 14 operate in a manner which is well known in the art and are adapted to complete an electric circuit when their associated movable contacts 56 and 58 are engaged by the actuating member 16 to generate an electrical signal which activates other electrical circuitry, also known in the art, to, for example, reverse the direction of rotation of the particular electrical device to be controlled, such as an electric motor.

Referring to FIG. 8, there is illustrated a modified actuating member 74 having an L-shaped member 77 attached to the top of the leg of the T-shaped member 62 by the screw 65. By providing members 77 of various lengths, the amount of travel of the actuating member 16 between the limit switches 12 and 14 can be varied to suit any desired application.

In either embodiment of the invention, if the shaft 18 is the output shaft of an electric motor, for instance, the actuating device can be used to control the direction and number of revolutions of such an output shaft. After the electric motor has been energized to rotate the shaft 18 a predetermined number of revolutions, the appropriate limit switch will be engaged by either member 63 or the member 77 to reverse the direction of the electric motor. The shaft 18 will then be rotated in a reverse direction until the opposite limit switch is engaged by either the member 63 or the member 77, whereupon the direction of rotation of the electric motor is again reversed.

The present invention has particular application to electric motors in that a limit switch assembly can be provided for such devices by simply clamping the assembly of the present invention to the output shaft of the motor. Heretofore it would have been necessary to undertake expensive modifications of the output shaft or to provide another shaft coupled to the output shaft to provide a limit switch assembly for electric motors.

Having thus described the invention, what is claimed is as follows:

1.An actuating device comprising:

an actuating member mounted for movement toward at least one contact point;

a rotatably mounted shaft having at least one continuous helical path circumscribing said shaft along a selected length thereof, a portion of said actuating member extending into said helical path and movable along said selected length in response to the rotational movement of said shaft;

said helical path comprising spaces between successive turns of a wire wound around said shaft, the adjacent sides of each turn of said wire normally being abutment and being axially separable to accommodate said actuating member portion as said actuating member moves along said selected length.

2. The actuating device defined in claim 1 and in which said wire is rectangular in cross section and has a pair of edges of a smaller dimension than another pair of said edges, said wire being wound about said shaft on one of its shorter edges so that the longer edges define the depth of said helical path, the adjacent longer edges of said wire normally being in abutment.

3. The actuating device as defined in claim 1 includhaving a slotted portion generally parallel to the axis of rotation of said shaft, said actuating member being mounted in said slotted portion, said switches being mounted on said base proximate one end of said slotted portion and adapted to be engaged by said actuating member as the same is driven along said slotted portion by said rotating shaft.

7. The actuating device as defined in claim 6 wherein said wire has a radial width which substantially exceeds its axial thickness, said wire being wound around said shaft on one of its edges such that the radial width of said wire defines the depth of said helical path.

8. The actuating device as defined in claim 7 including means for releasably attaching said wire to said shaft.

Claims

1. An actuating device comprising: an actuating member mounted for movement toward at least one contact point; a rotatably mounted shaft having at least one continuous helical path circumscribing said shaft along a selected length thereof, a portion of said actuating member extending into said helical path and movable along said selected length in response to the rotational movement of said shaft; said helical path comprising spaces between successive turns of a wire wound around said shaft, the adjacent sides of each turn of said wire normally being abutment and being axially separable to accommodate said actuating member portion as said actuating member moves along said selected length.

3. The actuating device as defined in claim 1 including means for releasably attaching said wire to said shaft.

4. The actuating device as defined in claim 3 wherein said releasably attaching means comprises a pair of clamps attaching the opposite ends of said wire to said shaft.

5. The actuating device of claim 1 including at least one switch disposed in the path of said actuating member.

6. The actuating device as defined in claim 5 including a mounting bracket having a base and at least one flange extending at right angles thereto, said bracket being mounted to said shaft by said flange, said base having a slotted portion generally parallel to the axis of rotation of said shaft, said actuating member being mounted in said slotted portion, said switches being mounted on said base proximate one end of said slotted portion and adapted to be engaged by said actuating member as the same is driven along said slotted portion by said rotating shaft.