US3072757A

US3072757A - Electromechanical device

Info

Publication number: US3072757A
Application number: US4061A
Authority: US
Inventors: Gluck William
Original assignee: UNITED INTERNATIONAL DYNAMICS CORP
Current assignee: UNITED INTERNATIONAL DYNAMICS CORP
Priority date: 1960-01-22
Filing date: 1960-01-22
Publication date: 1963-01-08
Anticipated expiration: 1980-01-08
Also published as: GB925257A

Description

Jan. 8, 1963 w. GLUcK ELECTROMECHANICAL DEVICE 5 Sheets-Sheet 1 Filed Jan. 22, 1960 lill? INVENTOA WILLIAM GLUCK ATTORNEYS W. GLUCK ELECTROMECHANICAL DEVICE Jan. s, 1963 3 Sheets-Sheet 2 Filed Jan. 22, 1960 INVHVTOR.

ATTORNEYS Jan. 8, 1963 w. GLUcK Y 3,072,757

ELECTROMECHANICAL DEVICE Filed Jan. 22, 1960 5 Sheets-Sheet 5 IN VEN TOR.

WILUAM GLUCK ATTORNEYS United States Patent O 3,072,757 ELECTROMECHANICAL DEVICE William Gluck, Waltham, Mass., assigner to United International Dynamics Corp., Boston, Mass., a corporation of Massachusetts Filed Jan. 22, 1960, Ser. No. 4,061 Claims. (Cl. 200-16) The present invention relates in general to electrical switches and more particularly concerns a novel snapaction sliding contact switch capable of establishing exceptionally good contact for many cycles of operation. Its few parts are easy to assemble, facilitating automatic production and `reducing cost.

Typical prior art sliding contact switches comprise three spaced aligned iixed contacts with a sliding contact establishing a conductive path between the center contact and a selected one of the end contacts. Frequently, means including a separate spring cooperate With a detent to maintain the sliding contact in the selected position and provide snap action. These switches are characterized by a number of disadvantages. The number and nature of parts is such that assembly is difficult, time consuming and generally must be accomplished by hand. After a relatively short time, these switches become noisy because good Contact is not established between one or more of the fixed contacts. When multiple pole switching is desired, additional strain is placed on the detent and spring unless additional springs and detents are added, thereby increasing cost and the complexity of the structure. This problem is better understood when it is recognized that multiplying the number of poles proportionately increases the frictional forces between the contacts to additionally strain a single detent and single spring.

The present invention has as an important object the provision of a compact snap action switch having relatively few parts which are easy to assemble rapidly and automaticall'y, yet is capable of smoothly switching relatively high currents for many operating cycles.

It is another object of the invention to provide a switch .in accordance with the preceding object capable of providingV multiple pole switching.

Still another object of the invention is to provide a toggle switch in accordance with the preceding objects.

Still a further object of the invention is to provide a switch having a sliding contact also functioning as a spring and detent for providing snap action.

Still another object of the invention is to provide a housing which acts upon a sliding contact in accordance with the preceding object which may be constructed in one piece.

According to the invention, a slidable switch contact is formed of a resilient strip of conducting material having a pair of opposed extremities forming substantially circular arcs separated by a central portion with respective top portions extending from said extremities away y from the central portion and toward a line generally perpendicularly bisecting the line joining the centers of the circular arcs. Preferably, the central portion is formed With a protrusion which cooperates with a xed contact to provide detent action for maintaining the switch in the selected position and rocking and snap action during switching in a manner described in detail below.

Fixed contacts are insulatedly separated and supported by suitable support means along a path traversed by the sliding contact. A housing has means for urging the sliding contact top portions toward the fixed contacts and is formed with opposed end walls which contact respective ones of the extremities of the sliding contact substantially tangential to the circular arcs. This housing is relatively movable with respect to the means for support- 1 lCC ing the -tixed contacts. The opposed end Walls in the housing are preferably sloped so that they may exert a force on the sliding contact directed toward the arc centers. This force may be resolved into two orthogonal components; one urging the sliding contact against the iixed contacts; the other urging the sliding contact along the path toward the newly selected switch position.

Numerous other features, objects and advantages of the invention will become apparent from the following specification when read in connection with the accompanying drawing in which:

FiGS. l and 2 show a snap action single pole switch according to the invention;

FIGS. 3-5 are partial longitudinal sectional views through the structures of FIGS. 1 and 2 corresponding essentially to section 3 3 of FIG. 1;

FIG.' 6 is an exploded View of the structure shown in FIGS. l-S;

FIG. 7 is a side view of the novel sliding contact showingits different positions when deected during switching;

FIG. 8 is an end sectional View of the structure shown in FIGS. l-7 corresponding essentially to section 8-8 of FIG. 2;

FIG. `9 is an end sectional view through a double pole switch according to the invention;

FiG. l0 is an exploded view of such a double pole switch;

FIG. l1 is a longitudinal sectional view through a tog- .gle switch arranged according to the invention; and

FIG. 12 is a longitudinal sectional view through another form of toggle switch according to the invention.

With reference now to the drawings and more particularly FIGS. 1 and 2 thereof, there are shown views of a completed slide snap action single pole switch ac cording to the invention. Two end xed contacts 11 and 12 are separated by a center xed contact 13, each of the contacts being formed with lugs for connection to external circuits. A rectangular bottom plate 14 made of insulating material, such as cardboard or plastic, supports and insulatedly separates the fixed contacts 11-13 `along a path followed by the internal sliding contact. A metal covering plate 15 is formed with tabs 16 which -it snugly in grooves in the bottom plate 14. The tabs 16 .inward while urging the ears 17 on each tabapart.

A housing 21 is formed with a protrusion extending through the rectangular opening 22 in the metal housing 15. The housing 21 is formed with arecess for accommodating the sliding contact. Metal covering plate 15 includes a pair of holes 23 forinserting screws or other suitable devices to fasten the switch to an associated chassis. l l

Referring to FIG. 3, there is shown a partial longitudinal sectional View of the switch shown in FIGS. l and 2'. The same reference numerals identify corresponding ele ments throughout the different portions of the drawings.

The sliding Contact 24 is shown accommodated in the housing 21 in a position electrically connecting end terminal 111 with center terminal 13. The sliding contact 24 is formed of a resilient strip of conducting material, such as Phosphor bronze, having a pair of

opposed extremities

25 and 26 forming substantially circular arcs of substantially 225 and separated by a central portion 27 The upper wall 33 presses downward on

upper portions

31 and 32 to urge the central portion 27 of sliding contact 24 against the xed contacts 11 and 13. The sloping

opposed end walls

34 and 35 are arranged to contact

end portions

25 and 26, respectively at points such that the respective end walls are tangential to the circular arcs at the points of contact. The angle between said perpendicular bisector and each sloping end wall is approximately When the switch has just been operated to urge the sliding contact 24 to the left, the arcuate portion 26 is contacted by the sloping end wall 35. When the switch is in the process of being moved to the right, the sliding contact 24 appears generally as shown with the arcuate portion 25 tangentially contacted by the end wall 34 as shown in FIG. 4.

In FIG. 5, the position of the sliding Contact 24 is shown just as the protrusion 28 passes over the center contact 13. The switching action is rapid, positive and smooth. The curved surfaces of the protrusion 28 and the fixed contact 13 result in the former smoothly passing over the latter and rapidly urging the sliding contact to its new rest position. The center of the protrusion 28 passes over the center of lthe iixed contact 13 so that the resilient sliding contact 24 expands and exerts a force on the sliding contact `13 tending to urge the protrusion 28 away from the contact 13. Thus, the protrusion comprises a detent and helps provide a rolling vand snap action during switching.

Briey reviewing the mode of operation during switching, the sloping wall of the housing at the end where contact is to be broken initially prevents the arcuate end of the sliding contact from rising while urging the sliding contact toward the end where contact is to be made. The protrusion of the sliding contact climbs the center fixed contact, raising the end of the sliding contact which will make contact upon completion of the switching cycle and compressing or loading that resilient arcuate end. These events occur during the first half of the switching cycle.

On the next half of the switching cycle, the protrusion reaches the top of the center fixed contact and a rocking and snap action follows as the loaded or compressed end of the sliding contact expands to force this end to make the new contact. At the same time, the sliding contact tips so that the other end of the sliding contact breaks contact.

Referring to FIG. 6, there is shown an exploded view of the switch illustrated in the preceding drawings. By inverting this exploded view, the simplicity of the assembly operation becomes apparent. The housing 21 is dropped into the metal casing 15. The sliding contact 24 is dropped into the well of the housing 21.

After the fixed contacts 11-13 are dropped into the slot pairs 37-39, respectively, in the supporting plate 14, the latter is fitted over the tabs 16. These tabs are bent inward while the ears of each are urged apart to secure the assembly in place.

Referring to FIG. 7, there is shown a side view of the sliding contact Z4. Normally, this contact is in the position indicated by the solid lines. During the course of sliding from one position to another, the sliding contact 24 is deformed to the positions indicated by the dashdot lines 37 and broken lines 38, respectively. Observe that Ithis deformation consists essentially of a rolling of the

top portions

31 and 32 and

arcuate portions

25 and 26 about the inwardly translating centers of the circular arcs. This type of deformation results in a soft but rm spring contact being regularly maintained by the sliding contact against the lixed contacts with a slight increase in pressure during switching to provide detent action. Good electrical contact is thus maintained between relatively large contacting areas to enhance current carrying capacity while mechanical wear is minimized.

The

top portions

24 and 25 are effectively cantilevered from the

arcuate portions

25 and 26, respectively. Since the bending moment of a cantilevered member increases as the point of suspension is approached, it may `be desirable to increase the thickness of the metal in the region near the effective cantilever suspension point along the arcuate portions. This point seems to be approximately above the centers of the respective arcs. However, excellents results have been obtained with sliding contacts 24 made of metal having a constant thickness.

Referring to FIG. 8, there is shown a sectional view through the width of the switch illustrated in the preceding ligures helpful in recognizing certain advantages of the relationship between sliding and iixed contacts. The iixed contacts are preferably portions of the surface of a cylinder having its axis transverse to Ithe path followed by the relatively wide sliding contact. This provides a relatively large surface Contact area between the sliding Contact and each iixed contact to help insure good contact capable of handling relatively large currents while lessening contact pressure to help minimize mechanical wear.

Referring to FIG. 9, there is shown an end sectional View of a double pole switch according to the invention and FlG. 10 shows an exploded view of such a switch. Since the structure is essentially the same as that of the single pole switch described above, further description is believed unnecessary and corresponding portions of the switching section associated with the second pole are identified by the same reference numeral used to designate the corresponding element in preceding portions of the drawing with an appended prime. Note that the structure is readily adaptable to multiple pole switching without sacricing its electrical and mechanical advantages and with a less than proportionate cost increase.

Referring to FIG. l1, there is a longitudinal sectional view of a snap action toggle switch according to the invention. Since this View best illustrates the principles of this embodiment and the remaining constructional details are apparent to one having ordinary skill in the art from this View and the specification, other views of this embodiment are not shown. The support means 41 insulatedly separates

end contacts

42 and 43 and center Contact 44 along a curved path travelled by sliding contact 24. The housing 45 in which the sliding contact 24 is accommodated has a top Wall 46 and

opposed end walls

47 and 48 corresponding to the

walls

33, 34 and 35 respectively. It is pivotally supported in the support means 41 by a pin 46.

Still another form of toggle switch is shown in FIG. 12 by means of a longitudinal sectional View in which the embodiment of FIGS. 1-8 is slightly modified by forming the housing 21 with a well 51 which accommodates the protrusion 52 from the toggle 53 so that the rotative motion of the latter about its pin 54 is converted into a linear displacement of the housing 21. The metal casing 15 is formed to accommodate a toggle support housing 55 which in turn supports the pin 54.

There has been described a novel switch characterized by positive snap action to provide reliable electrical contact despite a large number of operations. The switch is capable of carrying relatively high currents for its compact size, requires relatively few parts and is easily assembled, being suitable for assembly by automatic means.

While only relatively few embodiments of this invention have been illustrated, numerous other embodiments will be suggested to those skilled in the art from examining the drawings and reading the specification. For example, the principles could be employed for a continuously rotatable sliding contact housing wherein the sliding contact was connected to a terminal of the housing to provide sequential commutation to two or more successive terminals. It would also be within the principles of this invention to have a sliding contact in contact with only one fixed cont-act at a time by appropriately adjusting the length of the sliding contact with respect to the spacing between fixed contacts, external v connection to the sliding Contact being provided by suitable means. Numerous other modications of and departures from the specic embodiments described herein will be apparent to those skilled in the art without departing from the inventive concepts. Conse quently, the invention is to be construed as limited only by the spirit and scope of the appended claims.

What is claimed is:

1. A slideable switch comprising a iirst contact formed of a resilient strip of conducting material having a p-air of opposed extremities forming substantially circular arcs each greater than 180 separated by a central portion with respective top portions joining a respective arc below the top of the arc and extending from said extremities away from said central portion and toward a line generally perpendicularly bisecting the line joining the centers of said circular arcs, a plurality of spaced contacts defining a path, a housing having first and second end walls embracing said rst contact for tangential contact with respective ones of said circular arcs in respective tangential planes tangential to said arcs at each point of tangential contact, the angle between each of said tangential planes and said perpendicularly bisecting line being much less than 45, and means for supporting the assembly comprising said housing and said first contact in relatively movable relationship to said plurality of spaced contacts in a direction generally parallel to said path to selectively interconnect at least two adjacent ones of said pluralityl of contacts.

2. A slideable switch contact in accordance with claim 1 and further comprising a convex protrusion at said central portion. Y

3. A slideable switch contact in accordance with claim 2 wherein said strip of conductlng material is formed with said convex protrusion extending away `from said top portions.

4. A slidable switch in accordance with claim l and further comprising, a top Wall in said housing for contacting said top portions and urging said first contact toward said path.

5. A switch in accordance with claim l wherein said path is defined substantially by a straight line.

6. A switch in accordance with claim 5 and further comprising, a pivotally mounted toggle and means for converting rotation of said toggle about its pivot point to translation of said housing along said path.

7. A switch in accordance with claim l wherein said path is defined substantially by a curved line.

8. A switch' "in accordance with claim 7 wherein said housing is pivotally mounted and formed with a toggle.

9. A switch in accordance with claim l wherein the cross-section of each of said contacts and said protrusion in a plane defined -by said path and said line conforms substantially to a circular arc.

10. A switch comprising, a plurality of contacts, support means insulatedly separating said contacts and supporting same in spacial relationship along a plurality Y yof parallel paths, a like plurality of resilient conducting sliding contacts each having a pair of opposed extremities forming substantially circular arcs each greater than separated by a central portion, each of said sliding contacts also having respective top portions joining a respective arc below the top of the arc extending from said extremities away from said contacts and toward a line perpendicularly bisecting the line joining the centers of said circular arcs, and a housing having means for urging said top portions toward said contacts and having a like plurality of recesses, each recess having opposed end walls which contact respective ones of said extremities of a respective sliding contact substantially tangential to said circular arcs to establish respective tangents at the points of contact having components parallel to said line greater than components perpendicular to said line, said support means and said housing being relatively movable to allow said sliding contacts to move along said parallel paths, each pair of opposed end walls embracing a respective one of said sliding contacts for tangential contact with respective ones of said circular arcs in respective tangential planes tangential to said arcs at each point of tangential contact, the angle between each of said tangential planes and said perpendiculrly bisecting line being much less than 45.

References Cited in the le of this patent UNITED STATES PATENTS 2,686,851 Sanda Aug. 17, 1954 2,762,880 Hathorn et al Sept. 1.1, 1956 2,785,240 Carling Mar. 12, 1957

Claims

1. A SLIDEABLE SWITCH COMPRISING A FIRST CONTACT FORMED OF A RESILIENT STRIP OF CONDUCTING MATERIAL HAVING A PAIR OF OPPOSED EXTREMITIES FORMING SUBSTANTIALLY CIRCULAR ARCS EACH GREATER THAN 180* SEPARATED BY A CENTRAL PORTION WITH RESPECTIVE TOP PORTIONS JOINING A RESPECTIVE ARC BELOW THE TOP OF THE ARC AND EXTENDING FROM SAID EXTREMITIES AWAY FROM SAID CENTRAL PORTION AND TOWARD A LINE GENERALLY PERPENDICULARLY BISECTING THE LINE JOINING THE CENTERS OF SAID CIRCULAR ARCS, A PLURALITY OF SPACED CONTACTS DEFINING A PATH, A HOUSING HAVING FIRST AND SECOND END WALLS EMBRACING SAID FIRST CONTACT FOR TANGENTIAL CONTACT WITH RESPECTIVE ONES OF SAID CIRCULAR ARCS IN RESPECTIVE TANGENTIAL PLANES TANGENTIAL TO SAID ARCS AT EACH POINT OF TANGENTIAL CONTACT, THE ANGLE BETWEEN EACH OF SAID TANGENTIAL PLANE AND SAID PERPENDICULARLY BISECTING LINE BEING MUCH LESS THAN 45*, AND MEANS FOR SUPPORTING THE ASSEMBLY COMPRISING SAID HOUSING AND SAID FIRST CONTACT IN RELATIVELY MOVABLE RELATIONSHIP TO SAID PLURALITY OF SPACED CONTACTS IN A DIRECTION GENERALLY PARALLEL TO SAID PATH TO SELECTIVELY INTERCONNECT AT LEAST TWO ADJACENT ONES OF SAID PLURALITY OF CONTACTS.