US3676812A

US3676812A - Plunger operated reed relay switch

Info

Publication number: US3676812A
Application number: US162496A
Authority: US
Inventors: Voyta E Wrabetz
Original assignee: Square D Co
Current assignee: Schneider Electric USA Inc
Priority date: 1971-07-14
Filing date: 1971-07-14
Publication date: 1972-07-11
Anticipated expiration: 1989-07-11
Also published as: CA956675A; IT964663B

Abstract

The invention relates to a plunger operated reed relay switch module that incorporates a novel permanent magnet and mounting for the magnet which permits the plunger which operates the magnet to have the same travel characteristics as a plunger which actuates the contacts in a plunger operated snap switch. The switch module thus may be used as a replacement for a snap switch in a device when the device is required to control the input signals in a solid state logic circuit.

Description

United States Patent Wrabetz [4 1 July 11, 1972 [54] PLUNGER OPERATED REED RELAY 3,613,038 10/1971 Bell ..200/67 F x SWITCH 3,621,415 11/1971 Bell ..200/67FX [72] Inventor: Voyta E. Wrabetz, Hubertus, Wis. Primary Examiner Bemard A Gilheany [73] Assignee: Square D Company, Park Ridge, 111. Assistant Examiner-R. N. Envall, Jr. [22] Filed: July 14 1971 Attorney-Harold J. Rathbun et a1.

[21] Appl. No.2 162,496 [57] ABSTRACT The invention relates to a plunger operated reed relay switch U.S. 67 F module that incorporates a novel peflnanent magnet and [51] Int. Cl. ..H0lh 5/00 mounting f the magnet which permits the plunger which [58] Field of Search ..335/205, 206, 207; 200/67 F operates the magnet to have the same travel characteristics as a plunger which actuates the contacts in a plunger operated [56] References Cited snap switch. The switch module thus may be used as a replace- UNITED STATES PATENTS ment for a snap switch in a device when the device is required 7 to control the input signals in a solid state logic circuit. 3,423,705 1/1969 Cherry et a1 ..200/67 F X 3,611,219 10/1971 lwami ..200/67 F X 10 Claims,6Draw1ngfigures Patented July 11, 1972 mwe F. 3% 1W ||1 F INVENTOR.

' VOYTA E. WRABETZ PLUNGER OPERATED REED RELAY SWITCH This invention relates to reed relay switch modules and is more particularly concerned with a plunger operated reed relay switch module which is especially suited to be used as a substitute for a plunger operated snap switch in a device which is required to control a solid state circuit.

A dry reed switch is a well known device that comprises a pair of resilient metal reeds which extend axially into an evacuated tube from opposite ends thereof with their tip portions overlapping in the medial portion of the tube and laterally spaced apart by a small distance. The reeds are magnetically permeable; hence when a magnet field is caused to thread both of the reeds and the gap between the reeds, the tip portions of the reeds are magnetically attracted and the reeds flex into switch closing engagement with each other.

It has been long appreciated that reed switches possess many desirable characteristics that adapt them for use in applications involving hostile environments and low voltage and current circuits as may be present in solid state logic circuits. However, reed switches also are fragile and while they are capable of reliably making and interrupting low voltage and current circuits, they are incapable of controlling larger currents as are required by devices, such as limit switches, which are used in control circuits of solenoids, control relays and motor starters which control the motion of machine tools, conveyors and practically every type of motor driven machine.

One form of a limit switch, as shown in U.S. Pat. No. Re. 27,016, which was reissued on Dec. 29, 1970 to Rudolf H. Kiessling and Carl A. Schaeffer, includes a housing wherein one or more plunger operated snap switches are included and an external operator which operates the plungers of the snap switches. While the limit switch in the Kiessling et al. patent has been successfully used in typical limit switch circuits, it is not particularly suited for use in solid state circuits because the contacts in the snap switches are susceptible to oxidation and are not designed to operate in circuits having currents and voltages present in solid state circuits.

While it is possible to design a limit switch which has an operating mechanism expressly designed to operate a reed switch, a more economical approach is to provide a limit switch which is capable of operating both a snap switch and/or a reed switch, so the same limit switch may readily be converted to a control conventional limit switch circuit and/or a solid state circuit. This result is achieved by providing a reed switch module, as will be hereinafter described, which has the same operating characteristics as a snap switch so the reed switch module may be substituted for the snap switch in a limit switch or other device which is conventionally used to actuate a snap switch in a manner well known to those skilled in the art.

It is an object of the present invention to provide a reed switch module which may be substituted for a plunger operated snap switch in a switching device.

An additional object is to provide a reed switch module with a magnet structure which will have a concentrated magnetic field and a pivot mounting which will permit a plunger, which controls the movement of the magnet, to have the same travel characteristics as a plunger operated snap switch.

A further object is to provide a reed switch module with a housing that encloses a reed switch and a permanent magnet and provides a guide for a movable plunger which, when moved between two positions in the housing, causes an arched portion on the magnet to swing between two positions relative to a contact gap portion of the reed switch.

Another object is to provide a reed switch module with a permanent magnet that has side walls of opposite polarity extending between two opposite ends of the magnet and to provide an archway at one of the ends of the magnet, which receives the envelope of a reed, so the magnetic field between the side walls is concentrated by the archway.

Further objects and features of the invention will be readily apparent to those skilled in the art from the following specification and from the appended drawings illustrating certain preferred embodiments, in which:

FIG. 1 is a front plan view of a plunger operated reed switch module incorporating the features of the present invention.

FIGS. 2 and 3 are front views of the switch module in FIG. 1 with a cover portion of the module removed and respectively showing the internal components of the module when the plunger is in a deactuated position and an actuated position.

FIG. 4 is an exploded view showing in perspective the operating components of the switch in FIGS. 2 and 3.

FIGS. 5 and 6 are respectively a side and a front view of a permanent magnet used in the module in FIGS. 2 and 3.

A switch module 10, shown in the drawing, includes a housing 12 and a cover 14 which are formed of a molded insulating material and define an internal cavity 16. The housing 12 has a pair of apertured ears 18 extending outwardly from a lower wall 20 and a passage 22 extending inwardly through a top wall 24 into the cavity 16. The ears 18 are provided so the module 10 may be mounted in a device or on a support, not shown, and the passage 22 provides a guide for a plunger 26. The plunger 26 is movable within the passage 22 and includes a portion 28 that is movable within the cavity 16 and a portion 30 that extends externally of the top wall 24. Positioned within the cavity 16, and extending through suitable openings in the cover 14, are three

brass terminal members

32, 34 and 36, each of which has a strip-like shape. The terminal member 32 is positioned at the lower left-hand corner of the cavity 16 adjacent a left side wall 38 of the housing 12 by a projection 40. The projection 40 extends forwardly in the cavity 16 from a rear wall 42 portion of the housing 12. The

terminal members

34 and 36 are positioned adjacent a right side wall 44 of the housing 12 respectively at the upper and lower right hand corners of the-cavity 16 by a projection 46 which extends forwardly from the rear wall 42. The

projections

40 and 46 have front surfaces spaced forwardly from the rear wall 42.

A commercially available reed switch 48 is positioned within the cavity 16 adjacent the rear wall 42 and includes a sealed glass envelope 50, preferably filled with an inert gas. A pair of

reeds

52 and 54, which act as stationary contacts for the reed switch 48, extend into the interior of the envelope 50 from the right end of the envelope 50. The

reeds

52 and 54 are not required to be flexible and respectively have tip portions 56 and 58 located at a medial portion of the envelope 50 and are connected to

terminal members

60 and 62 respectively at the right end of the envelope 50. The

terminal members

60 and 62 have portions positioned upon the front surface of the projection 46 and have their respective ends secured, as by welding, to the

terminal members

34 and 36 respectively. The tip portions 56 and 58 are spaced from each other and are respectively located adjacent the upper and the lower inner side walls of the envelope 50. The reed 52 is formed of a nonmagnetically permeable material and the reed 54 is formed of a magnetically permeable material. The reed switch 48 additionally includes a flexible reed 64 of magnetically permeable material that extends into the interior of the envelope 50 from the left end of the envelope 50. The reed 64 extends from a tip portion 66 which is located in the space between tip portions 56 and 58 so as to overlap slightly with either of the tip portions 56 or 58 to a terminal member 68 which has a portion positioned on the front surface of the projection 40 and an end secured, as by welding, to the terminal member 32. The reed 64 is preloaded so that the tip portion 66 normally engages the tip portion 56 and is flexible so that the tip portion 66 will move into engagement with the tip portion 58 in response to a magnet field which threads the reeds 54 and 64 and the gap between the tip portions 58 and 66.

A permanent magnet assembly 70, which is pivotally movable within the cavity 16, includes a magnet metal part 72 and a magnet holder 74. The magnet holder 74 is preferably formed of a suitable plastic material, such as nylon, and includes a recess wherein the magnet part 72 secured as by an adhesive, so that the magnet part 72 and the magnet holder 74 effectively act as a unitary part within the cavity 16.

The magnet part 72 and the magnet holder 74 are shaped so the magnet assembly 70 has a pair of

opposite side walls

76 and 78 extending parallel to each other between a lower end 80 and an upper end 82 of the magnet assembly 70. The end 80 has a U-shaped archway 84 extending between the

side walls

76 and 78 and a portion of the side wall adjacent the end 82 has a groove 86 which receives a pivot pin 88 to pivotally mount the magnet assembly 70 in the cavity 16. The magnet part 72 is polarized so the

side walls

76 and 78 have opposite magnet polarities. The pivot pin 88 is immovably positioned by the housing 12 and extends from the rear wall 42 in the cavity 16 so that the envelope 50 of the reed switch 48 is received in the archway 84 when the pivot pin 88 is received in the pivot groove 86. The pin 88 is located so the medial portion of the envelope 50 is centered in the archway 84 when the magnet assembly 70 is positioned as in FIG. 2 and is displaced from the archway 84 when the magnet assembly 70 is at the osition shown in FIG. 3. The magnet assembly is also provided with an actuating surface 90 on the side 78 that is adjacent the end 82 which is constantly engaged by an apex 91 on a resilient finger 92 to maintain the pin 88 in the groove 86.

As previously described, the reed switch 48 is positioned adjacent the rear wall 42 of the cavity 16. The portion 28 of the plunger is movable in a space in the cavity 16 located between the reed switch 48 and the inner surface of the cover 14. The portion 28 has a bore, not shown, extending upwardly from a bottom end 94 which receives a portion of a spring 96. The spring 96, which has an end positioned on the lower wall 20, biases the plunger 26 upwardly in the housing 12. The upward movement of the plunger 26 is limited by a stop portion 98 on the left side of the portion 28 which engages a stop surface 100 on the top wall 24. The right side of the portion 28 is provided with vertically extending recess 102 and a surface 104 adjacent the bottom end 94 which has a circular boss 106 projecting from the surface 104. The resilient finger 92 is formed of a flexible metal to have a strip-like shape and includes an opening 108 at its lower end which receives the boss 106 and the apex 91 at its upper end which engages the surface 90 on the magnet assembly 70. The finger 92 is maintained in an assembled position on the portion 28 of the plunger so as to be movable in the recess 102 by positioning a lower portion of the finger 92 on the surface 104 with the boss 106 received in the opening 108 and ultrasonically staking the free end of the boss 106 over the surface portions of the finger 92.

The switch module is assembled by positioning the envelope 50 in the archway 84 and inserting the components of a sub-assembly consisting of the reed switch 48, the

terminal members

60, 62 and 68 and the

terminal members

32, 34 and 36 within the cavity 16 with the envelope 50 positioned within the archway 84 while the groove 86 is positioned on the pivot pin 88. A sub-assembly, including the plunger 26, the resilient finger 92 and the spring 96, is then positioned in the cavity 16. The assembly of the switch module 10 is completed when the cover 14 is secured on the open front of the housing 12 by a suitable screw, not shown, which passes through an opening 112. The screw has a threaded position received in an opening in a rear surface of the cover 14 and a headed portion engaging a rear surface on the rear wall 42.

The switch module 10 is shown in FIG. 2 in its deactuated condition wherein the spring 96 causes the plunger to be moved to a position wherein the stop surfaces 98 and 100 are engaging and the apex 91 is positioned above a horizontal plane passing through the pivot pin 88. The engagement between the apex 91 and the actuating surface 90 will position the magnet assembly 70 so that the side wall 78 engages the surface 104 and the archway 84 is positioned at the medial portion of the envelope 50 whereat the tips 56, 58 and 66 are located. When the magnet assembly 70 is positioned as in FIG. 2, the magnet flux field between the

side walls

76 and 78 will be concentrated within the archway 84 and will pass through the magnet metal reeds 54 and 64 as well as the gap between the tip portions 58 and 66. The magnet flux through the gap between the tip portions 58 and 66 causes the tip portions 58 and 66 to have opposite magnetic polarities and the tip portion 66 to move into engagement with the tip portion 58. When the tip portions 58 and 66 are engaging, an electric circuit is completed between the terminal 32 and the terminal 36.

The switch module 10 is actuated when an external force applies to the plunger 26, against the spring return force provided by the spring 96, causes the plunger 26 to move into a housing 12 to the position shown in FIG. 3. The movement of the plunger 26 from the position shown in FIG. 2 to the position shown in FIG. 3, causes the apex 91 to move across the actuating surface from a position where the apex 91 is above the horizontal plane through the pin 88 to a position where the apex 91 is below the horizontal plane. The movement of the apex 91 across the actuating surface 90 will cause the magnet assembly 70 to swing in a counterclockwise direction to a position whereat a portion of the magnet assembly 70 engages a fixed stop 114 on the housing. When the magnet engages the stop 114, the archway 84 and the magnet field in the archway 84 will be displaced relative to the medial portion of the envelope 50 so that the tip 66 is no longer magnetically attracted toward the tip 58. The reed 64 thus is free to move, and because of its prestressed condition, causes the tip 66 to engage the tip 56 and a circuit between the terminal 32 and the terminal 34 to be completed.

One of the advantages embodied in the switch module 10 is that the distance between the pivot pin 88 and the apex 91 is substantially less than the distance between the pivot pin 88 and the archway 84 so that a small movement of the apex 91 across the actuating surface 90 will cause a large swinging motion of the end of the permanent magnet carrying the archway 84. Thus only a small movement of the plunger 26 is required to cause the archway 84 to swing to its displaced position relative to the medial portion of the envelope 50. After the magnet assembly 70 is moved into engagement with the stop 114, a continued motion of the plunger 26 will be without effect as the resilient finger 92, which is biased toward the magnet assembly 70, causes the magnet assembly 70 to remain in engagement with the stop 114 so that the movement of the plunger 26 may be continued after the magnet assembly 70 has moved to its deactuated position. Thus the operation of the switch module 10 can be made to resemble that of a conventional snap switch which requires considerable plunger travel to actuate the switch contacts.

While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto, as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims.

What is claimed is:

l. A switch module comprising: a switch housing having an internal cavity, a permanent magnet pivotally mounted within the cavity, said permanent magnet having: opposite side walls of opposite magnetic polarity extending between two opposite ends, an archway extending between the side walls at a first of the two ends, a pivot portion at a second of the two ends pivotally mounting the magnet on the housing so that the first end is swingably movable between two positions in the cavity, and an actuating portion at the second end, a reed switch including: an elongated tubular envelope and a pair of magnetically permeable electrically conducting reeds extending axially in the envelope to provide a pair of engageable contact tip portions at the medial portion of the envelope, means for mounting the reed switch within the cavity so that the medial portion is received in the archway and a magnetic flux is induced in said pair of reeds when the first end of the magnet is at a first of its two positions and the archway and medial portion are displaced relative to each other when the first end of the magnet is at a second of its two positions, and a plunger having an operating portion engaging the actuating portion on the magnet, said operating portion being movable between two positions in the cavity for moving the first end of the magnet to the first of its two positions when the operating portion is at one of its two positions and for moving the first end of the magnet to the second of its two positions when the operation portion is at a second of its two positions.

2. A switch module comprising: a switch housing having an internal cavity, a permanent magnet pivotally mounted within the cavity, said permanent magnet having: opposite side walls of opposite magnetic polarity extending parallel to each other between two opposite ends of the magnet, an archway extending between the side walls at a first of two ends, a pivot groove at a second of the two ends extending parallel to the side walls, and an actuating portion at the second end of the magnet, a pin carried by the housing and received in the pivot groove for mounting the magnet in the cavity so the first end is swingably movable between two positions in the cavity, a reed switch including: an elongated tubular envelope, a magnetic permeable conductive contact member fixed to a first end of the envelope and extending axially thereinto, a magnetically permeable resiliently flexible reed mounted at a second end of the envelope and extending axially thereinto, said reed and contact member extending into the envelope to provide a pair of contact tip portions which are in overlapping relationship at the medial portion of the envelope and normally spaced apart when the reed is at a first position and said reed being flexible so that the reed is flexed toward the contact member to move the tip portions into engagement when a magnetic flux is induced in the reed and the contact member and the reed is at a second position, means for mounting the reed switch in the cavity so the envelope is received in the archway during the swinging movement of the first end of the magnet and for positioning the medial portion so the magnet flux is induced in the reed and contact member and the reed is flexed to its second position when the first end of the magnet is at a first of its two positions and so that the archway and medial portion are displaced and the reed and contact member are in their normally spaced apart positions and the reed is at its first position when the first end of the magnet is at a second of its two positions, and a plunger having an operating portion engaging the actuating portion on the magnet, said operating portion being movable between two positions in the cavity for moving the first end of the magnet to the first of its two positions when the operating portion is at one of its two positions and for moving the first end of the magnet to the second of its two positions when the operating portion is at a second of its two positions.

3. The switch module as recited in claim 1 wherein the reed switch includes an additional contact member that is nonmagnetically permeable and includes a tip portion that is engaged by the tip portion on the reed when the reed is at its first position.

4. The switch module as recited in claim 1 wherein the operating portion on the plunger is provided by a resilient member.

5. The switch module as recited in claim 1 wherein the distance between the archway and the pivot portion is greater than the distance between the actuating portion and the pivot portion.

6. The switch module as recited in claim 4 wherein the pivot portion and the actuating portion are disposed on opposite sides of the magnet, the pivot portion is provided by a groove extending in one of the side walls and a pin which is supported by the housing and received in the groove, and the resilient member engages the actuating portion and maintains the pin within the groove during movements of the magnet to its two positions.

7. The switch module as recited in claim 6 wherein the resilient member maintains the pin in the groove when the plunger is moved beyond one of its two positions.

8. The switch module as recited in claim 7 wherein the plunger is movable along a linear path in the housing, a spring biases the plunger to a first of its two positions, the magnet is at its first position when the plunger is at its first position and is moved with a swinging movement about its pivot portion to its second position when the plunger is moved to a second of its two positions.

9. The switch module as recited in claim 1 wherein the archway is U-shaped.

10. The switch module as recited in claim 9 wherein the pivot portion and the actuating portion are disposed on opposite sides of the magnet, the pivot portion 15 provided by a groove extending in one of the side walls and a pin which is supported by the housing and received in the groove, and the resilient member engages the actuating portion and maintains the pin within the groove during movements of the magnet to its two positions.

Claims

1. A switch module comprising: a switch housing having an internal cavity, a permanent magnet pivotally mounted within the cavity, said permanent magnet having: opposite side walls of opposite magnetic polarity extending between two opposite ends, an archway extending between the side walls at a first of the two ends, a pivot portion at a second of the two ends pivotally mounting the magnet on the housing so that the first end is swingably movable between two positions in the cavity, and an actuating portion at the second end, a reed switch including: an elongated tubular envelope and a pair of magnetically permeable electrically conducting reeds extending axially in the envelope to provide a pair of engageable contact tip portions at the medial portion of the envelope, means for mounting the reed switch within the cavity so that the medial portion is received in the archway and a magnetic flux is induced in said pair of reeds when the first end of the magnet is at a first of its two positions and the archway and medial portion are displaced relative to each other when the first end of the magnet is at a second of its two positions, and a plunger having an operating portion engaging the actuating portion on the magnet, said operating portion being movable between two positions in the cavity for moving the first end of the magnet to the first of its two positions when the operating portion is at one of its two positions and for moving the first end of the magnet to the second of its two positions when the operation portion is at a second of its two positions.

9. The switch module as recited in claim 1 wherein the archway is U-shaped.

10. The switch module as recited in claim 9 wherein the pivot portion and the actuating portion are disposed on opposite sides of the magnet, the pivot portion is provided by a groove extending in one of the side walls and a pin which is supported by the housing and received in the groove, and the resilient member engages the actuating portion and maintains the pin within the groove during movements of the magnet to its two positions.