GB1597643A

GB1597643A - Rotary shaft position indicator or control

Info

Publication number: GB1597643A
Application number: GB98678A
Authority: GB
Original assignee: Rose J F; Wolford B F
Current assignee: Rose J F; Wolford B F
Priority date: 1977-01-12
Filing date: 1978-01-11
Publication date: 1981-09-09
Also published as: DE2800724A1; NL7800349A; JPS53104868A

Description

(54) ROTARY SHAFT POSITION INDICATOR OR CONTROL (71) We, BYRON F. WOLFORD and JOHN F. ROSE, both citizens of the United States of America, of Fergus Falls, Minnesota, and Underwood, Minnesota, both in the United States of America, respectively, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates broadly to a device for indicating or controlling the rotational position of a rotary shaft, and more particularly, to a rotary shaft position indicator or control for use in harsh environmental conditions.

The present invention is particularly applicable to fluid and other flow systems in which it is desirable to monitor the condition of rotary valves (i.e. open or closed) and/or to control the opening or closing of successive valves in the flow line as a function of the open or closed state of the preceeding valves.

Typically, in the prior art, electrical switches that are mechanically actuated in response to the operative state of the rotary valve have been utilized. However, these mechanically actuated switches suffer from the disadvantage that, where subjected to severe environmental conditions including dust, moisture, or other corrosive or explosive foreign matter, they are deleteriously affected, and over a period of time may malfunction causing erroneous indicator or control signals. If, for example, a switch fails to generate an "open" or "closed" signal to a successive valve in a fluid flow system, it can be readily appreciated that serious consequences to the system operation may develop.

The present invention obviates the disadvantage referred to above in that it provides a rotary shaft position indicator or control in which a switch is enclosed within a housing that is sealed against the above-mentioned deleterious matter. The switches are actuated utilizing a magnetic coupling through a nonmagnetic wall of the housing. Thus, rotary shaft position indicator or control signals are generated utilizing switches which remain unaffected by the harsh environmental conditions that may exist in particular system applications.

Accordingly, in a first aspect the present invention provides a rotary shaft position indicator or control comprising: a housing having a switch cavity and including means for sealing said housing from the exterior surroundings of said housing whereby said switch cavity is protected from dust, moisture, corrosive or explosive foreign materials; switch means disposed within said switch cavity for providing indication or control signals when actuated; a rotatable spindle mounted within said cavity and having a first axis of rotation, said spindle further having means for selectively actuating said switch means upon rotation of said spindle; a first magnet secured to said rotatable spindle; a second magnet having a second axis of rotation and magnetically coupled through a wall of said housing to said first magnet whereby upon rotation of said second magnet said spindle is thereby rotated; and means for coupling the rotary shaft to said second magnet whereby the rotational axis of the rotary shaft may be misaligned with respect to said second axis of rotation.

In a second aspect the invention provides a position indicator or control for a rotary shaft comprising: a housing having a switch cavity and including means for sealing said housing from the exterior surroundings of said housing whereby said switch cavity is protected from dust, moisture, corrosive or explosive foreign materials; a switch disposed within said switch cavity for providing indication or control signals when actuated; a rotatable spindle mounted within said cavity and having a first rotational axis; a switch actuating member secured to said rotatable spindle and positioned to selectively actuate said switch; a first magnet secured to said rotatable spindle; a second magnet magnetically coupled through a wall of said housing to said first magnet, said second magnet having a second rotational axis normally aligned with said first rotational axis, said second magnet having means for securing said second magnet to the rotary shaft; and means for mounting said second magnet to the exterior of said housing, said mounting means comprising bearing means for permitting misalignment of said first and said second rotational axes.

In one embodiment of the invention, a plurality of microswitches having pivotally mounted spring-biased switch actuating arms are disposed within the sealed switch cavity. A plurality of cams, each cam associated with a separate switch, are secured to a rotatable spindle mounted within the switch cavity. Attached to the rotatable spindle is an annular magnet positioned proximate a nonmagnetic wall of the device housing. A second annular magnet is disposed proximate the non-magnetic wall exterior of the switch cavity and is secured to the rotary shaft. The annular magnets are magnetically coupled through the non-magnetic housing wall such that upon rotation of the rotary shaft the rotatable spindle also rotates in harmony. The cams are provided with cam surfaces which contact the switch actuating arms at selected rotational positions of the rotary shaft. The cams are adjustably mounted to the rotatable spindle to vary the rotational position of the switch actuation of selected switches or to delay or advance the actuation of the switches as the rotary shaft changes its rotational position. The means for coupling the rotary shaft to said second magnet is conveniently a resilient fastener, typically a spring clip. This fastener dampens any shocks inherent in the rapid change of the rotary shaft from one position to another.

Thus, each of said first and second aspects of the invention provides a rotary shaft position indicator or control in which the electrical or other switches which generate the indication or control signals are sealed within a cavity and protected from potentially harsh environmental conditions. The switches are actuated through a magnetic coupling.

There is now described, by way of example and with reference to the accompanying drawings, a rotary shaft position indicator or control which is a preferred embodiment of the invention.

In the drawings: Figure 1 is a side elevational view of the rotary shaft position indicator or control operatively mounted to sense the position of a valve mechanism; Figure 2 is an enlarged end elevational view of the position indicator and control seen generally from the line 22 of Figure 1; Figure 3 is an enlarged axial sectional view as seen from the line 3-3 of Figure 2; Figure 4 is a transverse sectional view as seen from the line 4-4 of Figure 3; Figure 5 is a transverse sectional view as seen from the line 5-5 of Figure 3; Figure 6 is a fragmentary sectional view taken from Figure 3 with portions thereof broken away; Figure 7 is a view similar to Figure 6 and illustrating the misalignment of the rotational axis of the driving magnet of the device; and Figure 8 is a fragmentary sectional view of Figure 3 with portions thereof broken away and showing an alternative embodiment of the present invention.

Referring to the drawings, wherein like numerals represent like parts throughout the several views, one embodiment of the present invention is illustrated in Figure 1 operatively connected to a pneumatically actuated rotary valve. More particularly, the rotary shaft position indicator and control is indicated generally at 10 and includes an essentially cylindrical first housing member 12 and a spring clip 16 (which will be described in greater detail) by means of which it is coupled to a rotary shaft 14. Secured to rotary shaft 14 is a disc or butterfly-type valve member 18 which controls fluid flow through conduit 20. The positioning of valve member 18 is accomplished by a conventional pneumatic actuating device 22. The introduction or exhaust of air through lines 24 and 26 into pneumatic actuating device 22 functions to rotate shaft 14 and thereby position valve member 18.

Rotary position indicator and control 10 will now be described more particularly with reference to Figures 2-5. Cylindrical housing member 12 is threaded internally at 28. A second housing member 30 is provided with external threads at 32 which mate with the internal threads at 28. Housing members 12 and 30 define a switch cavity 34. An O-ring seal 36 is provided proximate the threaded connection between housing members 12 and 30. O-ring 36 is compressed when housing member 12 is screwed onto housing member 30. Cavity 34 is thus effectively sealed from the environment surrounding rotary position indicator and control 10.

Dust, moisture, or other corrosive or explosive foreign materials are prevented from entering cavity 34 by the seal between housing members 12 and 30. The seal between housing members 12 and 30 may also be achieved through mating surfaces on the housing members that are secured together by threaded fasteners.

Disposed within cavity 34 are a plurality of microswitches 38. Microswitches 38 are mounted vertically on screws 48 between an upper support plate 42 and an annular portion 44 of housing member 30. A plurality of spacer members 46 made of an insulating material position microswitches 38 along screws 48. The micro switches are illustrated more particularly in Figure 4. Each microswitch has a switch actuating arm 50 which is pivoted at 52 and biased by a spring 54 outward from a switch housing 56. Switch housing 56 has a projection 58 which acts as a stop to limit the rotation of actuating arm 50 about a pivot 52 under the influence of biasing spring 54. Switch make-or-break member 55 is positioned to be depressed or released by switch actuating arm 50. Microswitches 38 may be of any conventional type which provide snap-action in changing from one switching state to another. The switches shown in the drawing have a plurality of contacts 59, 60 and 62 which correspond to common, normally open, and normally closed states, respectively. Electrical conductors (not shown) are connected to contacts 59, 60 and 62 and lead from cavity 34 through a channel 64 formed in a projecting portion 66 of housing member 30. An electrical conduit 68 is threadably received within an aperture 70 in projecting portion 66. The threaded connection of conduit 68 to portion 66 is also sealed or potted to insure that cavity 34 is isolated from the environment.

Switch actuating arms 50 are themselves actuated by a plurality of cams 72 disposed along and secured to a rotatable spindle 74.

Cams 72 are secured to spindle 74 by set screws 76. Extending beyond the outer surface of cams 72 are set screws 78 which contact switch actuating arms 50 to depress the switch actuating arms against the bias of spring 54. Cams 72 are positioned about spindle 74 such that selective ones of the plurality of microswitches 38 are actuated at various rotational positions of spindle 74. As will be hereafter described, the rotational position of spindle 74 is directly related to the rotational position of shaft 14. Spindle 74 is rotatably mounted to support plate 42 through a ball bearing 77 received in a recess in spindle 74 and in contact with a retaining member 79 threadably engaging an aperture in support plate 42. Spindle 74 is in contact with a non-magnetic wall 80 of housing member 30 through a second ball bearing 82 captured between a recess in spindle 74 and a recess in non-magnetic wall 80. Secured to the lower end of spindle 74 is an annular magnet 84 having single or multiple north and south poles as indicated in Figure 3.

Disposed opposite wall 80 is a second annular magnet 86 also having similar but opposite north and south poles as indicated.

Magnet 86 is held within an outwardly facing chamber 88 defined on the exterior of housing member 30 by an annular plate 90 secured by screws 92 to housing member 30.

A ball bearing 94 is captured between annular magnet 86 and housing wall 80 to permit rotation of annular magnet 86 in response to the angular rotation of shaft 14.

Annular magnet 86 is integral with a magnet support member 96 to which is secured spring clip 16. As shown in Figure 1, a coupling member 15 attached to shaft 14 is received within spring clip 16. Spring clip 16 provides a somewhat resilient connection between shaft 14 and annular magnet support 96 to dampen any shocks that might be transmitted due to the rapid changes of rotary valve position. It is to be understood that spring clip 16 is merely one method of transmitting the rotational motion of shaft 14 to magnet 86 contemplated within the scope of the present invention. For example, magnet 86 may have a shaft to which is secured a lever that is actuated by shaft 14. The rotary shaft position indicator could then serve as a limit switch. An annular layer of insulating material, for example plastic, is sandwiched between retaining plate 90 and housing member 30 to provide a rotational sliding surface for annular magnet 86. A similar piece of insulating material 100 is provided as a cover for a chamber 102 in which annular magnet 84 is housed.

The operation of the embodiment disclosed in Figures 1-5 will now be described.

Cams 72 will typically be secured to spindle 74 such that set screws 78 are in angular orientations about spindle 74 to open or close selected switches 38 in a predetermined sequence relative to the angular position of shaft 14. It should be noted that switches 38 could be of any snap-acting type having on and off states. Annular magnet 84 rotates in conjunction with the rotation of annular magnet 86 since the magnets are magnetically coupled through non-magnetic wall 80 by an attractive magnetic force. The north and south poles of annular magnets 84 and 86 align with magnetic flux fields locking the magnets into synchronism. Microswitches 38 may provide a number of indication or control functions. For example, in addition to generating a signal corresponding to an open or closed condition of valve member 18, the change of position of valve member 18 may through one of the microswitches 38 control the opening or closing of additional valve members in conduit 20. The timing of the opening or closing of successive valve members in conduit 20 may be critical, and therefore to accurately regulate such valve functions the cam members 72 can be adjusted in their positioning about spindle 74 to advance or delay the actuation of actuating arms 50 by contact with set screws 78.

The magnetic coupling between shaft 14 and spindle 74 also allows for overtorquing with no damage to the position indicator and control. For example, if shaft 14 is overtorqued, the poles of magnet 86 will simply "slip" or override the poles of magnet 84 thereby "skipping" to the next attractive magnetic field. The device can be reset to the proper alignment of magnetic fields without disassembly by merely rotating shaft 14 to the appropriate position.

The threaded connection and O-ring seal between housing member 12 and housing member 30 effectively isolates switch cavity 34 from the surrounding environment. Microswitches 38 are therefore not subjected to dust, moisture or other corrosive or explosive contaminants. System failures, due to problems encountered when the microswitches are subjected to such severe environmental conditions are eliminated in the present invention. A threaded connection and O-ring are illustrated in the preferred embodiment, and it is to be understood that alternative means of providing a sealed switch cavity 34 are contemplated within the scope of the present invention.

As shown in Figures 3 and 6, spindle 74, magnet 84, and magnet 86 each have rotational axes that are aligned with each other.

Ball bearings 77, 82, and 94 provide selfaligning bearing means that allow for some misalignment of the rotational axes. In particular, Figure 7 illustrates the misalignment of the rotational axis of driving magnet 86 with respect to the rotational axis of driven magnet 84 and cam spindle 74. More specifically, a generally vertical broken line A designates the rotational axis of cam spindle 74 and driven magnet 84. The rotational axis of driving magnet 86 is designated as B and the misalignment angle between axes A and B is designated as C. It is not uncommon for such misalignment to occur during the attachment of the device of the present invention to rotary shaft 14. Such misalignment may be necessitated by virtue of the various structures of rotary shaft actuators 22. However, the self-aligning bearing means of the present invention allows such misalignment without sacrificing performance of the rotary shaft position indicating device 10.

The self-aligning bearing support means provided by ball bearings 77 and 82 provide a production tolerance permitting some misalignment of the axis A with respect to a line perpendicular or normal to wall 80. Again, by virtue of the self-aligning bearing means of the present invention, misalignment of cam spindle 74 would not affect the operating performance of the present invention. By and large, however, it will be more common that some misalignment of the rotational axis B of driving magnet 86 will be necessary.

Figure 7 illustrates a misalignment wherein axis B may be described as being misaligned in a clockwise direction with respect to axis A. It is understood, however, that misalignment wherein axis B may be described as being disposed counterclockwise universaly 360 with respect to axis A is also permitted by the present invention. As shown in Figure 7, magnet support 96 bears against an inner edge portion 97 of annular layer 95 causing inner edge portion 97 to deflect outwardly from chamber 88. Annular layer 95 is preferably a flexible Nylatron washer (Nylatron is a Trade Mark). A second nylatron washer (not shown) may be affixed to wall surface 99 of chamber 88. Although the significant portion of the misalignment will be taken up by means of the self-aligning bearing means, spring clip 16 is somewhat resilient, as has been described, and therefore, will deflect somewhat as illustrated in Figure 6, to also permit misalignment with respect to shaft 14.

The degree of misalignment permitted by the self-aligning bearing means is determined by the size of chamber 88. Preferably, chamber 88 will be sized to allow a maximum amount of misalignment and yet maintain magnetic coupling between driving magnet 86 and driven magnet 84.

Figure 8 illustrates an alternative embodiment of the self-aligning bearing means in the device of the present invention. In particular, cam spindle 74' is provided with tapered end portions 120 and 122 having terminal pointed ends 124 and 126, respectively. Support plate 42' may be provided with a suitable bearing material member 128 which has a conical recess at 130 engaged by pointed end 126. Wall 80' is also provided with a suitable bearing material member 134 with conical recesses 136 and 138 oppositely exposed therein. Pointed end 124 is received within recess 138. Driving magnet 86' is provided with a rod member 140 disposed axially along the rotational axis of magnet 86'. Rod member 140 has a tapered end portion 142 terminating in a point 144 which is received within conical recess 136. The taper end portions 120, 122, and 142 is typically a 70 degree taper while the taper of the conical recesses are typically 90 degrees.

Figure 8 illustrates the rotational axes of cam spindle 74', magnet 84', and driving magnet 86' in alignment. However, point mounts on cam spindle 74' and rod 140 permit misalignment of the rotational axes as previously described and illustrated with respect to Figure 7.

While two alternative embodiments of bearing structures are disclosed, it is understood that other self-aligning bearing configurations are also contemplated within the scope of the present invention. For example, commercial self-aligning bearings may be utilized. Additionally, cam spindle 74 may be provided with spherical end portions received within generally concave recesses as opposed to pointed end portions received within conical recesses. Similarly, rod member 140 could be provided with a somewhat rounded end portion received within a concave recess in wall 80'. Finally, it is also contemplated that ball bearings 82 and 77 could be fixed to the ends of spindle 74 as opposed to being merely captured between spindle 74 and the mounting recesses.

The present invention, thus, solves the problems associated in the prior art rotary shaft position indicator and controls which have experienced system malfunctions primarily as a result of failures of microswitches subjected to harsh environmental conditions.

By providing for actuation of the microswitches in a sealed cavity utilizing magnetic coupling, the switch cavity remains unaffected by such environmental elements.

While each of the above embodiments discloses rotary shaft position indicator and controls utilizing electrical switches, it is also contemplated that pneumatic, fluidic or hydraulic switches are within the scope of the present invention.

Although the devices of this invention are referred to herein by the term "rotary shaft position indicator or control", the invention also includes devices which can be used for the purposes of indication and control.

WHAT WE CLAIM IS: 1. A rotary shaft position indicator or control, comprising: a housing having a switch cavity and including means for sealing said housing from the exterior surroundings of said housing whereby said switch cavity is protected from dust, moisture, corrosive or explosive foreign materials; switch means disposed within said switch cavity for providing indication or control signals when actuated; a rotatable spindle mounted within said cavity and having a first axis of rotation, said spindle further having means for selectively actuating said switch means upon rotation of said spindle; a first magnet secured to said rotatable spindle; a second magnet having a second axis of rotation and magnetically coupled through a wall of said housing to said first magnet whereby upon rotation of said second magnet said spindle is thereby rotated; and means for coupling the rotary shaft to said second magnet whereby the rotational axis of the rotary shaft may be misaligned with respect to said second axis of rotation.

2. A rotary shaft position indicator or control according to Claim 1, wherein said second magnet is mounted to the exterior of the housing by means of a bearing.

3. A rotary shaft position indicator or control, according to Claim 2, wherein said bearing permits misalignment of said first and second rotational axes.

4. A rotary shaft position indicator or control according to Claim 1, 2 or 3, in which said means for coupling the rotary shaft to the second magnet is a spring clip, secured to said second magnet and adapted to receive one end of the rotary shaft.

5. A rotary shaft position indicator or control according to any of the preceding claims, wherein said switch means comprises a plurality of switches disposed within said switch cavity; and said means for selectively actuating said switch means comprises a plurality of switch actuating members secured along said rotatable spindle, each of said switch actuating members positioned to selectively actuate one of said switches.

6. A rotary shaft position indicator or control according to Claim 5, wherein said switches have spring-biased switch actuating arms and wherein said switch actuating members comprise adjustable cams which contact said switch actuating arms.

7. A rotary shaft position indicator or control according to Claim 6, wherein said adjustable cams comprise: cylindrical members having apertures along their central axes which receive said rotatable spindle; adjustable set screws received in threaded apertures in said cylindrical members, said set screws extending beyond the outer periphery of said cylindrical members to contact said switch actuating arms.

8. A rotary shaft position indicator or control according to Claim 6 or 7, having means for varying the position of said cam members circumferentially about said rotatable spindle such that said switches may be actuated at predetermined variable rotational angular positions of said rotary shaft.

9. A rotary shaft position indicator or control in accordance with any of Claims 4 to 8 in which said means for coupling said rotary shaft to said second magnet can dampen the shock transmitted by said rotary shaft in response to rapid changes in the rotational position of said rotary shaft.

10. A rotary shaft position indicator or control, according to any of Claims 4 to 9, wherein the spring clip is cupshaped.

11. A position indicator or control for a rotary shaft comprising: a housing having a switch cavity and including means for sealing said housing from the exterior surroundings of said housing whereby said switch cavity is protected from dust, moisture, corrosive or explosive foreign materials;

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. scope of the present invention. For example, commercial self-aligning bearings may be utilized. Additionally, cam spindle 74 may be provided with spherical end portions received within generally concave recesses as opposed to pointed end portions received within conical recesses. Similarly, rod member 140 could be provided with a somewhat rounded end portion received within a concave recess in wall 80'. Finally, it is also contemplated that ball bearings 82 and 77 could be fixed to the ends of spindle 74 as opposed to being merely captured between spindle 74 and the mounting recesses. The present invention, thus, solves the problems associated in the prior art rotary shaft position indicator and controls which have experienced system malfunctions primarily as a result of failures of microswitches subjected to harsh environmental conditions. By providing for actuation of the microswitches in a sealed cavity utilizing magnetic coupling, the switch cavity remains unaffected by such environmental elements. While each of the above embodiments discloses rotary shaft position indicator and controls utilizing electrical switches, it is also contemplated that pneumatic, fluidic or hydraulic switches are within the scope of the present invention. Although the devices of this invention are referred to herein by the term "rotary shaft position indicator or control", the invention also includes devices which can be used for the purposes of indication and control. WHAT WE CLAIM IS:

1. A rotary shaft position indicator or control, comprising: a housing having a switch cavity and including means for sealing said housing from the exterior surroundings of said housing whereby said switch cavity is protected from dust, moisture, corrosive or explosive foreign materials; switch means disposed within said switch cavity for providing indication or control signals when actuated; a rotatable spindle mounted within said cavity and having a first axis of rotation, said spindle further having means for selectively actuating said switch means upon rotation of said spindle; a first magnet secured to said rotatable spindle; a second magnet having a second axis of rotation and magnetically coupled through a wall of said housing to said first magnet whereby upon rotation of said second magnet said spindle is thereby rotated; and means for coupling the rotary shaft to said second magnet whereby the rotational axis of the rotary shaft may be misaligned with respect to said second axis of rotation.

a switch disposed within said switch cavity for providing indication or control signals when actuated; a rotatable spindle mounted within said cavity and having a first rotational axis; a switch actuating member secured to said rotatable spindle and positioned to selectively actuate said switch; a first magnet secured to said rotatable spindle; a second magnet magnetically coupled through a wall of said housing to said first magnet, said second magnet having a second rotational axis normally aligned with said first rotational axis, said second magnet having means for securing said second magnet to the rotary shaft; and means for mounting said second magnet to the exterior of said housing, said mounting means comprising bearing means for permitting misalignment of said first and said second rotational axes.

12. A position indicator or control according to any of the preceding claims, wherein said wall of said housing has a recess therein, and wherein said bearing means comprises a ball bearing, said second magnet having a recess therein disposed along said second rotational axis, said ball bearing being captured between said recesses in said housing and said magnet.

13. A position indicator or control in accordance with claim 12, wherein said means for mounting said second magnet to said housing further comprises a flexible washer member engaging said second magnet and urging said second magnet toward said housing wall.

14. A position indicator or control in accordance with Claim 11, 12 or 13, wherein said rotatable spindle is normally mounted with said first rotational axis perpendicular to said wall of said housing and comprising bearing means for permitting said first rotational axis to be disposed at a misalignment angle with respect to said normal alignment.

15. A position indicator or control in accordance with claim 11, wherein said wall of said housing has a recess therein and wherein said bearing means comprises a rod member affixed to said second magnet and disposed along said second rotational axis, said rod member having a tapered end portion terminating in a contact point received in engagement with said wall within said recess.

16. A rotary shaft position indicator or control according to Claim 1, substantially as described herein with reference to the accompanying drawings.

17. A rotary shaft position indicator or control according to Claim 11, substantially as described herein with reference to the accompanying drawings.

18. A rotary shaft position indicator or control, substantially as described herein and substantially as shown in Figures 1 to 5 of the accompanying drawings.