US3297836A

US3297836A - Electrical switch

Info

Publication number: US3297836A
Application number: US529817A
Authority: US
Inventors: Thomas J O'malley
Original assignee: Grayhill Inc
Current assignee: Grayhill Inc
Priority date: 1966-02-24
Filing date: 1966-02-24
Publication date: 1967-01-10
Anticipated expiration: 1984-01-10

Description

ELECTRICAL SWITCH Filed Feb. 24, 1966 In a INVENTOR THOMAS J. O'MALLEY United States Patent 3,297,836 ELECTRICAL SWITH Thomas J. OMalley, Brooirfield, 1111., assignor to Grayhiil, Inc, La Grange, Ill., a corporation of Illinois Filed Feb. 24, 1966, Ser. No. 529,817 12 Claims. (Cl. 200-11) This invention pertains generally to electrical switches and more particularly to miniature multi-position switch structures.

The electronics industry has been faced with an ever increasing demand for miniaturization of components. Electrical switches are used in many applications in which space is critical. Miniaturization of switches, however, has presented problems. For instance, the space between contacts becomes small and even a small amount of foreign matter such as dirt that is generated within the switch or that penetrates the switch housing can foul the switch terminals and contacts and cause degradation of the electrical properties. Attempts to positively seal the housing against the entrance of such foreign matter and keeping the foreign matter generated in the housing away from the contacts has proven to be costly and in most instances not completely successful. Further, there has been a problem in providing the various switch structures required for different applications.

It is an object of this invention to provide an improved electrical switch that maintains the switch contacts, terminals and an area between the contacts free of foreign matter and that is relatively inexpensive to manufacture.

A further object is to provide a switch structure which is suitable for use in a large number of different applications.

It is common for consumers to require exacting specifications for a given switch. For instance, the specifications may require a minimum dielectric strength between switch terminals for a given number of hours or operations of the switch. In many structures, the switch housing and the base portion which supports the terminals are molded in one piece, making it extremely difficult to find a material that will have the required resistance to environmental deterioration desired in the housing, and the strength and electrical durability required of the terminal supporting portion.

Another object of this invention is to provide an improved electrical switch that has an area where mechanical and electrical wear products can collect without lowering the dielectric strength and the insulation resistance between terminals.

A further object of this invention is to provide an electric switch where the switch housing and the contact panel are made in separate pieces and from different materials which exhibit the characteristics most favorable to perform the function required of each piece.

A feature of this invention is a miniature electrical switch having a housing formed by closing the respective ends of a hollow cylindrical shell insulator with a cover plate and a contact panel, and having a plurality of spaced terminals circumferentially disposed about the contact panel, each terminal having a flat portion connected to the panel and radially extending beyond the periphery of the housing and a raised portion extending into the housing and forming a contact surface. A webbed insulator having an annular webbed portion with radially extending fingers is positioned on the contact panel so that the fingers intermesh between the raised terminal portions to form an insulating bridge therebetween. A plurality of wells are formed surrounding the raised terminals by the adjacent fingers, the annular web portion and the contact panel, whereby foreign matter generated in the switch or penetrating the housing falls into the wells to maintain proper insulation characteristics between terminals and to prevent fouling of the same.

Another feature of this invention is a miniature electric switch wherein a rotatable hub is supported on the annular web portion and in turn supports a U-shaped contact. An annular contact plate is recessed into the cover plate and is in contact with one leg of the U-shaped contact and resiliently biases the other leg of the same into contact with the raised portions of the terminals when the cover plate is in place. The fingers of the insulator are dimensioned to extend substantially the same amount into the housing as the raised terminal portions so that rotation of the hub to move the U-shaped contact from one terminal to the next causes the leg of the U-shaped contact engaging the terminals to intermittently contact the fingers of the insulator disposed between the terminal portions thereby removing foreign substance from the contact.

A further feature of this invention is a miniature electric switch wherein the rotating hub supports a plurality of U-shaped contacts each contacting a terminal portion, and the cover plate has a plurality of electrically isolated contact plates recessed therein, one for each U-shaped contact. Rotation of the hub to move the contacts between terminals is limited to provide multi-position, multipole operation of the switch.

In the drawings:

FIG. 1 is a side elevation view showing the switch housing and a housing for the selector mechanism connected thereto, in accordance with this invention;

FIG. 2 is an exploded plan view showing the components of the switch of FIG. 1;

FIG. 3 is a plan view of a partial assembly of the components of FIG. 2;

PEG. 4 is a plan view of a more complete assembly of the components shown in FIG. 2;

FIG. 5 is an enlarged elevation view of the crosssection of the switch housing shown in FIG. 1;

FIG. 6 is an enlarged elevation view in a cross-section showing the switch contact;

FIG. 7 is an enlarged elevation View in a cross-section showing a modification of the switch contact;

FIG. 8 is a plan view of one of the components in a second embodiment of the switch of FIG. 1;

FlG. 9 is a plan view of another component of the second embodiment of the switch in FIG. 1;

FIG. 10 is a cross-section front view of the mechanical actuating mechanism of the switch of FIG. 1 taken along the lines 1til.il therein;

FIG. 11 is a partialy broken away side elevation view of the mechanical actuating mechanism shown in FIG. 1;

FIG. 12 is an enlarged elevation view in cross-section showing a further modifications of the switch contact; and

FIG. 13 is a side elevation of a further embodiment of the electric switch of FIG. 1.

In one embodiment of the invention, a miniature electrical switch has a housing formed by closing the respective ends of a hollow cylindrical shell insulator with a cover plate and a contact panel. A plurality of spaced terminals are supported on the contact panel in circumferentially disposed relation. Each terminal has a flat portion connected to the panel that radially extends beyond the periphery of the housing, and a raised portion that extends into the housing and forms a contact surface. A webbed insulator includes an annular portion with spaced radially extending fingers that fits into the shell insulator, and rests on the contact panel. In this position the fingers intermesh between the raised terminal portions. A plurality of wells are formed surrounding each of the raised terminals by the adjacent fingers, the annular portion and the contact panel. Therefore, any

foreign particles that either enter the switch housing or are generated therein will fall into the wells thereby effectively preventing dielectric breakdown and serious degrading of insulation resistance between adjacent terminals and fouling of the same. A rotatable hub is supported by the annular web portion, and the hub in turn has a U-shape contact connected thereto. An annular contact plate is recessed into the cover plate and contacts one leg of the U-shape contact and resiliently biases the other leg of the same into contact with the raised portion of the terminals when the cover plate is in place. The fingers of the insulator are dimensioned to extend substantially the same amount into the housing as the raised terminal portions so that rotation of the hub to move the U-shape contact from one terminal to the next causes the leg of the U-shape contact contacting the terminals to intermittently contact the fingers of the insulator disposed between the terminal portions, thereby removing foreign substance from the contact.

In another embodiment, the rotating hub has a plurality of U-shaped contacts connected thereto each contacting a group of terminal portions, and the cover plate has a plurality of electrically isolated contact plates recessed therein, one plate for each U-shaped contact. Rotation of the hub to move the contacts between terminals is limited to provide multiposition, multipole operation of the switch.

In referring to the drawing, FIG. 1 illustrates the miniature electrical switch 13 composed of a housing 14 for the switch contacts and the housing 17 for the detent switching mechanism.

In FIGS. 2-7, a hollow cylindrical shell insulator 16 has a raised flange portion 15 on one end thereof and a serrated portion 18 (FIG. 3) about the periphery on the other end. Two cars 19 having apertures therethrough extend from the periphery of the shell and are used for mounting the same. A web insulator 20 is formed by an annular portion 22 and a plurality of spaced radially extending fingers 24. The web insulator 20 is connected to the shell insulator 16 (FIG. 3) by fitting the ends of the fingers 24 into the spaces of the serrated portions 18.

The shell insulator 16 with the web insulator 20 connected thereto is mounted to the contact panel 28 (FIG. 2) which closes off one end of the cylindrical shell 16 except for the aperture 29. The contact panel 28 has a plurality of spaced terminals 30 circumferentially disposed about the periphery thereof. The terminals 30 each have a flat portion 32 that is riveted 34 to the contact panel 28 and extends radially outwardly beyond the periphery thereof, and a raised portion 35 that extends into the housing formed by the shell insulator 16 to form a contact surface as best seen in FIG. 5. Bars 37, having apertures therein, extend from the panel 28 and are used for mounting the same. The shell insulator is mounted to the panel 28 with the

cars

19 and 37 aligned. In this position the web portion 22 rests on the panel, and the fingers 24 intermesh between the raised terminal portions 35 as shown in FIG. 4. The fingers 24 serve as dielectrics or insulators and cooperate with the air gaps between terminals to electrically insulate each terminal from the adjacent terminals. The remaining spaces 21 of the serrated portion 18 fit over the tops of the rivets 34 to provide a close lit for the shell 16 and webbed insulator 20 with panel 28.

A rotatable hub 40 (FIG. 2) has grooves 42 therein that terminate in slots 44 which extend through the hub 40. A U-shaped resilient contact 45 has a small spherical contact 47 on the leg 48, and a beveled contact 49 on the leg 50 (FIGS. and 6) that has a width less than the width of the space between the terminal portions 35 (FIG. 6). In the bend of the U is a substantially flat wedge portion 52 that slides into the slot 44 of the hub 40. In this position the

legs

48 and 50 extend out from the hub 40 through groove 42 when the U-shaped con- 4 tact 45 is connected to the hub 40. The hub 40 also has a slot 55 extending through the center thereof and is mounted in position on the annular web portion 22 of the web insulator 20 (FIG. 4) and closes the aperture 29 in the contact panel 28 except for the slot 55.

A metal annular contact plate 60 has an output terminal 62 extending beyond the outer periphery thereof and is recess fitted into the cover plate or cap 65, as best shown in FIG. 5. The cap 65 has ear portions 66 for mounting the cap, and a groove 68 in the skirt 69 of the cap 65 to permit the output terminal 62 to protrude through the cap. When the cap 65 is placed in position, the skirt 69 surrounds the flange 15 of shell 16 and rests on the wall of the shell thereby completing the housing 14 of the switch 13. In this position the plate 60 is in contact with the contact 47 of leg 48 and resiliently biases the beveled contact of leg 50 into contact with the raised portions 35 of the terminal 30. v

The mechanical detent mechanism in the housing 17 for rotating the hub 40 is generally known in the art but will be described briefly. It can be seen in FIG. 11 that a rectangular block 70 has

holes

72 and 73 bored in either end.

Springs

75 and 76 are inserted in the

respective holes

72 and 73, and act to bias balls 78 and 79 into scallop detents 80 to positively position the hub 40, and hence contact 45. An operating shaft is rotatably coupled to the housing 17 by a nut 83 which is threaded to bushing 86. An elongated rectangular shaft 82 is coupled to the operating shaft 85, and the rectangular block 76 is keyed to that shaft 82 so that movement of the operating shaft 85 turns shaft 82 to rotate the block 70 from detent to detent. A ring 88 (FIG. 10) is also keyed to the shaft and rides flush on the surface of rotating block 70. The ring has a radial projection or stop arm 90 thereon. Two flat annular rings 92, fit into and are keyed to housing 17 one on top of the other and close the housing. Each of the rings has a

projection

94 and 95 respectively extending into the annular openings. The

projections

94 and 95 serve as stops to arm 90 thereby limiting the rotation of the block 70. By varying the amount of separation between the stops or

projections

94 and 95 the total possible rotation of the switch is varied. If a full 360 of rotation is desired stop arm 90 may be removed.

The housing 14 is connected to the housing 17 by screws 97 (FIG. 1) that extend through the respective mounting ears of the

components

16, 28 and 65 into mounting ears 99 in the housing 17. This extends the actuating shaft 82 through the various components into the rotatable hub 40 which is moved by operating the shaft 85.

In operation, turning the shaft 85 causes the hub 40 to rotate to move the beveled contact 49 on leg 50 of contact 45 from one raised terminal portion 35 to the next adjacent terminal portion 35 providing single pole action. The beveled portion of contact 39 provides a smooth transition between the terminals. Because the webinsulator 20 is separate from the shell 16, it can be made of different material. This is a unique feature which is capitalized on in this instance, by making tthe web insulator 20 of a plastic material to which an abrasive material has been added which results in optimum rate of wear of the web and contact 49. The fingers 24 of the webbed insulator 20 extend as approximately as far into the housing as the raised terminal portions 35. Therefore, as the contact 49 crosses the fingers 24 when going from one terminal to the next, the abrasive character of the finger wipes the contact clean. At the same time, the shell which is one of the main structural mem bers can be made of a different material such as a molded plastic which will maintain the desired mechanical and electrical characteristics under various environmental conditions. This separation of the parts by function provides for the custom tailoring of the end product for the specific application requirements. In addition to providing a cleaning action for the contact, the fingers 24 provide another useful function. As the contact 49 breaks from one raised terminal portion 35 and on to the finger 24 the majority of the resultant arcing is in the air space between the terminal and the finger, thereby greatly reducing contamination between terminals.

The contact 45 may also be made into a make before break operation by making a slight modification or exclusion of the webbed insulator 20 as shown in FIG. 7. In this embodiment the fingers 24 are dimensioned to a height which is less than the height of the raised terminal portions 35 or the webbed insulator 20 and associated fingers 24 are removed completely. The beveled contact 63 is of suflicient length that, upon rotation of the hub 40, the contact 63 rotates off terminal portion 35 and passes over the finger 24 without contacting it, but it will contact the adjacent terminal portion 35 before it breaks contact from the terminal portion 35 it is leaving. In this mode of operation the finger portions still function to provide a long wearing dielectric insulator between each terminal 30.

A further unique feature of this invention is the fact that the intermeshed fingers 24 on either side of the terminal portion 35 cooperate with the annular portion 20 and the contact panel 28 to form individual wells 33 (FIG. 5) around the perimeter of the contact panel 28. Therefore, should any foreign matter be generated in the housing 14 or enter the same from the surrounding environment, rather than fouling the terminals and lying on the dielectric between the same, (such as where the terminals and dielectric lie in substantially the same plane) to cause degradation of the electrical properties between adjacent terminals, the foreign matter either initially falls into the wells 33 and lies on the contact panel 28 underneath the raised terminal portions 35, or is swept off the terminals by the sweeping action of the contact 49 down into the well. This action greatly adds to'the life and reliability of the switch.

Multipole operation of the switch 13 can also be accomplished. The cap or cover plate 65 previously described is replaced in this instance by the cap 105 (FIG. 8). The cap 105 is divided into six pie-shaped segments 106 by the integral webbed insulating portion 107. In each of the segments 106 is recessed a metal contact plate 109 which has an output terminal 110 integral therewith. The fingers 114 of the webbed insulating portion electrically isolates each plate 109 from the adjacent ones. Similar to cap 65, the cap 105 has mounting ears 112. The hub 115 replaces the hub 40 of the first described embodiment but is similar in all respects except that it has six U-shaped contacts 117 connected thereto.

In operation, the hub 115 is located within the housing 14 and is positioned so that each contact 117 contacts one of the raised terminal portions 35. The annular rings 92 (FIG. 10) are positioned to limit the rotation of the actuating shaft so that the hub 115 can only be rotated to position with contacts 117 between a pair of raised terminals 35. Within this limit of rotation of the contacts 117, each contact plate 109 serves as a pickoif for each pair of terminals 35. The result is that switch 13 now has two positions with six poles being contacted in each position. It should be obvious, of course, that the other combinations of con-tact plates and contacts on hub 115 are available depending on the number of poles on switch positions desired. By displaying such versatility with the modification of only a few pieces the switch can be made very economically.

Other useful combinations can be accomplished with the switch. For instance, the multipole operation as described above, some of the contact arms 117 could terminate with the narrow beveled contacts 49 shown in FIG. 6 and some with the wide beveled contacts 63 shown in FIG. 7. This arrangement would provide multipole break before make action with those arms 117 terminating in contacts 49 and make before break action with those arms 117 terminating in contacts 63, which are wide enough to make contact with the adjacent terminal before breaking contact with the terminal with which it was in contact, all with the same switching action. In addition, single pole switch action that combines both make before break and break before make switching is possible. FIG. 12 shows how this is accomplished. The beveled contact portion on contact 45 is approximately the same width as contact portion 63 in FIG. 7, that is, it can contact two terminal portions 35 at the same time. The fingers 102 of the web insulator 20 are dimensioned to a height less than the height of the portions 35 similar to the fingers 24 in FIG. 7, and the fingers 103 are dimensioned to a height so that they extend or raise above the raised terminal portions 35. Therefore, when the contact 50 is rotated, the contact portion 100 crosses the finger 102 of insulator 20 and performs a make before break switching action similar to that described in conjunction with FIG. 7. However, When the contact portion 100 crosses a finger 103 of the insulator 20, it is raised off the terminal portion 35 thereby breaking contact with that portion and is then moved into contact with the adjacent terminal as it slides off the finger 103 to provide the break before make function.

A further combination that should be considered is having a single pole switch, similar to that described previously, that uses a plurality of U-shaped contacts 50 connected in the rotating hub such as shown in FIG. 9. This switch could, of course, offer the various combinations of make before break and break before make switch operation as described.

Additional versatility of the switch 13 is indicated in FIG. 13. Here the housing 14 has another cap 120, shell insulator 121 and contact panel 122 combined to form another switching unit in housing 125 which is connected to the housing 14. The switching assemblies may be stacked to any reasonable number as required.

What has been described is an economical, versatile miniaturized multiposition switch structure that maintains the switch contacts and terminals free of foreign matter and that provides an area Where mechanical and electrical Wear particles can collect Without lowering dielectric strength between terminals. The shell insulator of the switch housing and the base portion that supports the switch terminals are made in separate pieces and from different materials exhibiting the characteristics most favorable to perform the function required of each piece.

What is claimed is:

1. A switch structure including in combination, a switch housing including a hollow cylindrical shell insulator with first and second open ends, a cover plate and a contact panel, said cover plate engaging said first end of said shell insulator and said contact panel engaging said second end thereof, a plurality of terminals secured to said contact panel and circumferentially disposed thereon, each of said terminals having a fiat portion connected to said contact panel and radially extending beyond the periphery of said housing and a raised portion extending into said housing and having a contact surface, an insulating web member including an annular portion having a plurality of radially extending spaced fingers, said insulating member being positioned on said contact panel with said fingers thereof positioned between said raised terminal portions and extending into said housing to electrically in sulate each of said terminals from the adjacent terminals, and rotor means having contact means engaging said raised portions of said terminals, said rotor means being adapted to be rotated for moving said contact means from one of said terminals to an adjacent terminal.

2. The switch structure of claim 1 wherein said fingers of said insulating web member are dimensioned to extend into .said housing approximately the same amount as said raised terminal portions, with rotation of said rotor means to move said contact means from one of said terminals to the next adjacent terminal causing said contact means to wipe across one of said fingers of said insulating web member to clean the contact surface thereof.

3. The switch structure of claim 1 wherein said web means and said contact panel cooperate to form a plurality of wells surrounding said raised terminal portions, so that foreign matter in said housing falls into said wells thereby preventing contaminant build-up between said terminals.

4. The switch structure of claim 1 wherein said insulating shell has a serrated portion about the periphery thereof, and said fingers of said web member interengage with said serrated portions to definitely position said web member with respect to said shell.

5. The switch structure of claim 1 With said fingers of said insulating member being dimensioned to be lower than said raised terminal portions, and said contact means being dimensioned to make contact with adjacent raised terminal portion before breaking contact with the preceding raised terminal portion.

6. The switch structure of claim 1 with said fingers of said insulating members being dimensioned to extend substantially the .same amount into said housing as said raised terminal portions, and said contact means being dimensioned to break contact with the preceding terminal portion before making contact with an adjacent terminal portion.

7. The switch structure of claim 1 wherein said rotor means includes a rotatable hub being supported on said annular portion, said contact means includes a substantially U-shaped resilient contact having first and second legs, and the switch structure further includes an annular contact plate recess fitted into said cover plate and having an output terminal portion radially extending beyond said housing, said contact plate contacting said first leg of said U-shaped contact and resiliently biasing said second leg of the same into contact with said raised portions of said terminals with said cover plate in position on said shell insulator.

8. The switch structure of claim 1 wherein said insulating web member is made of an insulating material that includes an abrasive material which results in an optimum rate of wear thereof, and said insulating shell is made of an insulating material which maintains the desired mechanical and electrical characteristics thereof under various environmental conditions.

'9. The switch structure of claim 1 wherein said rotor means includes a rotatable hub being supported on said annular web portion, said contact means includes a plurality of substantially U-shaped resilient contacts each having a portion in contact with one of said raised terminal portions, and the switch structure further includes a plurality of contact plates, and said cover plate having an integral web insulating portion dividing the same into a plurality of segments, each said contact plates being recessed in respective ones of said segments and being electrically insulated from one another by said integral web insulating portion, said cover being positioned on said shell insulator, said plurality of contact plates each biasing a portion of each of said contacts into engagement with a different one of said terminals, and said drive means rotating said hub to position said U-shaped contacts on a different one of said raised terminal portions thereby providing a multi-operation, multi-pole switch structure.

10. The switch structure of claim 9 wherein a first one of said portions in contact with said raised terminal portions is dimensioned to make contact with an adjacent raised terminal before breaking contact with the preceding raised terminal, and a second one of said portions is dimensioned to break contact with the preceding terminal portion before making contact with an adjacent terminal portion thereby providing rnulti-pole make before break and break before make switch operation in the same miniature switch structure.

11. A switch structure including in combination, a switch housing including a hollow cylindrical shell insulator with first and second open ends, a cover plate and a contact panel, said cover plate engaging said first end of said shell insulator and said contact panel engaging said second end thereof, a plurality of terminals secured to said contact panel and circumferentially disposed thereon, each of said terminals having a flat portion connected to said contact panel and radially extending beyond the periphery of the housing and a raised portion extending into said housing and having a contact surface, a rotatable hub being supported on said contact panel, contact means connected to said hub, said contact means including a substantially U-shaped resilient contact having first and second legs, an annular contact plate, said plate being mounted in said cover plate and having an output terminal portion radially extending beyond said housing, said contact plate contacting one of said legs of said U-shaped contact and resiliently biasing the other said leg of the same into contact with said raised portions of said terminals with said cover plate in position on said shell insulator, and drive means connected to said rotatable hub for moving said contact means from one of said terminals to an adjacent terminal.

12. The switch structure of claim 11 wherein said contact means further includes a beveled contact portionon one of said legs of said U-shaped contact, said contact portion being dimensioned to make contact with an adjacent raised terminal portion before breaking contact with the preceding raised terminal portion.

References Cited by the Applicant UNITED STATES PATENTS 1,900,236 3/1933 Hall. 2,980,770 4/ 1961 Nabstedt. 2,988,606 6/1961 Allison.

ROBERT K. SCI-IAEFER, Primary Examiner.

J. R. SCOTT, Assistant Examiner.

Claims

1. A SWITCH STRUCTURE INCLUDING IN COMBINATION, A SWITCH HOUSING INCLUDING A HOLLOW CYLINDRICAL SHELL INSULATOR WITH FIRST AND SECOND OPEN ENDS, A COVER PLATE AND A CONTACT PANEL, SAID COVER PLATE ENGAGING SAID FIRST END OF SAID SHELL INSULATOR AND SAID CONTACT PANEL ENGAGING SAID SECOND END THEREOF, A PLURALITY OF TERMINALS SECURED TO SAID CONTACT PANEL AND CIRCUMFERENTIALLY DISPOSED THEREON, EACH OF SAID TERMINALS HAVING A FLAT PORTION CONNECTED TO SAID CONTACT PANEL AND RADIALLY EXTENDING BEYOND THE PERIPHERY OF SAID HOUSING AND A RAISED PORTION EXTENDING INTO SAID HOUSING AND HAVING A CONTACT SURFACE, AN INSULATING WEB MEMBER INCLUDING AN ANNULAR PORTION HAVING A PLURALITY OF RADIALLY EXTENDING SPACED FINGERS, SAID INSULATING MEMBER BEING POSITIONED ON SAID CONTACT PANEL WITH SAID FINGERS THEREOF POSITIONED BETWEEN SAID RAISED TERMINAL PORTIONS AND EXTENDING INTO SAID HOUSING TO ELECTRICALLY INSULATE EACH OF SAID TERMINALS FROM THE ADJACENT TERMINALS, AND ROTOR MEANS HAVING CONTACT MEANS ENGAGING SAID RAISED PORTIONS OF SAID TERMINALS, SAID ROTOR MEANS BEING ADAPTED TO BE ROTATED FOR MOVING SAID CONTACT MEANS FROM ONE OF SAID TERMINALS TO AN ADJACENT TERMINAL.