US3573407A

US3573407A - Switching

Info

Publication number: US3573407A
Application number: US766401A
Authority: US
Inventors: Lyndon Walkup Burch; Hadley Keyes Burch
Original assignee: Individual
Current assignee: Individual
Priority date: 1968-10-10
Filing date: 1968-10-10
Publication date: 1971-04-06
Anticipated expiration: 1988-04-06

Abstract

A snap-action switch comprising a snap member carrying a first electrical contact connected to a first electrical contact connected to a first electrical terminal which can be snapped through an unstable center position by pressure applied through the contact, a stationary second electrical contact connected to a second electrical terminal and engaged by the first contact when the snap member is in a first stable position, a wedging member mounted for sliding movement along the stationary second contact between it and the first contact upon application of an actuating force, this wedging member being sized to push the first contact away from the second contact by means of an electrically conducting portion maintaining electrical current flow between the first contact and the stationary contact, until the snap member snaps through its unstable center position, and means for snapping the member back to the second contact; and an actuating structure, for actuating a snap member as described between two stationary contacts, comprising a first wedging member which slides between the stationary second contact and the first contact on the snap member to push the first contact away until the snap member snaps over, and a second wedging member which slides between the stationary third contact and the first contact, with return actuator movement, to push the snap member contact back against the stationary second contact, these wedging portions being spaced apart from each other to provide clearance for the snap member contact in its snap movements. In a preferred embodiment, these wedging members are conductive wires.

Description

United States Patent [72] Inventors Lyndon Walkup Burch Three River St. Place; Hadley Keyes Burch, Boston, Mass. (Pittsfield, Vermont 05762) [21] Appl. No. 766,401 [22] Filed Oct. 10, 1968 [45] Patented Apr. 6, 1971 Continuation-impart of application Ser. No. 567,633, July 25, 1966, now Patent No. 3,436,501.

[54] SWITCHING 12 Claims, 9 Drawing Figs.

[52] U.S. Cl 200/67, 200/68 [51] Int. Cl. H0lh 15/18 [50] Field of Search 200/16, 153.14, 67 (D2), 67 (D1), 67 (D), 68,151

[ 56] References Cited UNITED STATES PATENTS 2,191,926 2/1940 Lemire 200/16 2,753,413 7/1956 Anderson 200/151X 2,899,512 8/1959 Burch 00/67Dl(UX) FOREIGN PATENTS 6/1965 Great Britain 200/67D1 Primary Examiner-David Smith, Jr. Attorney-John Noel Williams ABSTRACT: A snap-action switch comprising a snap member carrying a first electrical contact connected to a first electrical contact connected to a first electrical terminal which can be snapped through an unstable center position by pressure applied through the contact, a stationary second electrical contact connected to a second electrical terminal and engaged by the first contact when the snap member is in a first stable position, a wedging member mounted for sliding movement along the stationary second contact between it and the first contact upon application of an actuating force, this wedging member being sized to push the first contact away from the second contact by means of an electrically conducting portion maintaining electrical current flow between the first contact and the stationary contact, until the snap member snaps through its unstable center position, and means for snapping the member back to the second contact; and an actuating structure, for actuating a snap member as described between two stationary contacts, comprising a first wedging member which slides between the stationary second contact and the first contact on the snap member to push the first contact away until the snap member snaps over, and a second wedging member which slides between the stationary third contact and the first contact, with return actuator movement, to push the snap member contact back against the stationary second contact, these wedging portions being spaced apart from each other to provide clearance for the snap member contact in its snap movements. In a preferred embodiment, these wedging members are conductive wires.

B L- 573L407 PATENTEUAPR slsm SHEET 1 OF 2 swrrcmuo This application is a joint continuation-in-part of a copending application, Ser. No. 567,633, filed Jul. 25, 1966, in the sole name of Lyndon Walkup Burch, entitled SWITCHING, now U.S. Pat. No. 3,436,501.

This invention relates to snap action electrical switches.

It is an object of this invention to provide an improved means for providing a quick make and break of snap action switch contacts.

It is another object to provide such means which also maintain, after snapping, proper contact engagement under vibration and acceleration.

Another object of this invention is to provide improvement along the lines indicated without the necessity of more parts than are used in conventional snap action switches and with little or no additional manufacturing costs.

It is another object of this invention to provide an improved means for actuating snap action switches having an unstable center position which utilizes the Wipe and Shear" principle disclosed in U.S. Pat. No. 2,899,512.

The invention features a snap action switch comprising a member carrying a first electrical contact connected to a first electrical terminal which can be snapped through an unstable center position by pressure applied through the contact, a stationary second electrical contact connected to a second electrical terminal and engaged by the first contact when the snap member is in a first stable position, a wedging member mounted for sliding movement along the stationary second contact between it and the first contact upon application of an actuating force, this wedging member being sized to push the first contact force away from the second contact, by means of an electrically conducting portion maintaining electrical current flow between the first contact and the stationary contact, until the snap member snaps through its unstable center position, and means for'snapping the member back to the second contact. In a preferred embodiment, the first, contact snaps to a third electrical contact, connected to a third electrical terminal; a second wedging member is provided to snap the member back to the second contact. The invention also features an actuating structure, for actuating such a snap member as described above between two such stationary contacts, comprising a first wedging member which slides between the stationary second contact and the first contact on the snap member to push the first contact away until the snap member snaps over, and a second wedging member which slides between the stationary third contact and the first contact, with return actuator movement, to push the snap member contact back against the stationary second contact, these wedging portions being spaced apart from each other to provide clearance for the snap member contact in its snap movements. In preferred embodiments, these wedging members have conducting portions to maintain current flow while separating the contacts until snap action occurs, and trailing insulating portions which press the snap member contact against the stationary contact after snap action occurs. In one preferred embodiment the wedging members are wires which slide along tapered insulatedcamming members first to snap the snap member and subsequently to press the snap member contact against the stationary contact.

Other objects, features and advantages will appear from the following description of a preferred embodiment of the invention taken together with the attached drawings thereof, in which:

FIG. 1 is a sectional view of an embodiment of the invention;

FIG. 2 is a side view of the embodiment of FIG. 1;

FIG. 3 is a cross-sectional view taken along line 3-3 of FIG.

FIG. 4 is a sectional view of a switch illustrating another embodiment of this invention with its contacts in a first position;

FIG. 5 is the same as FIG. 4, but with the contacts in a second position;

FIG. 6 is a perspective view of the actuator used in the embodiment of FIGS. 4 and 5;

FIG. 7 is a sectional view of a switch in accordance with still another embodiment of this invention with its contacts in a first position;

FIG. 8 is the same as FIG. 7 but with the contacts in a second position; and

FIG. 9 is a perspective view of an actuator for use in the embodiment of FIGS. 7 and 8.

Referring to the embodiment of FIGS. 1-3, a snap member in the form of an M" blade 10, as described in U.S. Pat. No. 3,213,288, is mounted on a stationary mount 12. On the short inner legs 14 is mounted a contact ball 16 which serves to transmit electrical current through the blade 10, and its mount to lead 18. The contact ball 16 also serves to stress the inner legs 14 apart, thereby stressing the blade 10 into a snap member relative to neutral plane P.

A pair of

stationary contacts

20 and 22, having parallel planar contact surfaces 21, 23, respectively, are mounted on support 24, the distances L and L between the respective contact surfaces 21, 23 and the unstable center plane of the snap member being equal.

A pair of intermediate wedging members 26, 28 are formed as an integral right-angle extension of

respective legs

27, 29 which are mounted to an actuator assembly 30 including an insulating block 31 which maintains said legs insulated from one another. In this embodiment the wedging members are formed of wire of 0.020 inch diameter.

Contacts

20, 22 are connected, respectively, to

terminals

32, 34.

Preferably as shown the wedging members are located to slide along and rub upon the respective stationary contact surfaces and are of a dimension greater than the distance between the contact ball 16 and the respective stationary contact surface when the snap member 10 is aligned with its neutral (unstable) plane.

In operation, the wedging members 26, 28 are moved between the respective contact surface and the contact ball 16, effective to force the ball away from the contact surface sufiiciently far to snap the blade 10 into its other snap position. Since members 26, 28 are also mounted on opposite sides of the contact ball 16 relative to the path D of movement of members 26, 28 movement of the actuator in the opposite sense along that path will cause opposite snapping of the member 10.

The time lapse between the break of contacts 20-16, e.g., and the make of contacts 22-16 may be further shortened if members 26, 28 are made of electrically conductive material, such that current may continue to flow through member 26, e.g., between

contacts

20 and 16 after direct physical contact between

contacts

20 and 16 has been broken until the snap member is snapped through its unstable center position to engage

contacts

16 and 22.

FIGS. 4 to 6 show a snap action switch and portions thereof having a snap-action element 40 which is again, for purposes of illustration, an integral thin sheet type blade member, specifically, an M blade in accordance with U.S. Pat. 3,213,288, to which reference is made for mounting details, etc. Housing 42 and actuator 44 are both of insulating material; actuator 44 is slidable in recess 46 of housing 42.

Snap-acting element 40 is fastened to a bracket 48, by a button 49, and has a pair of integrally formed

contacts

50, 51 on its active end.

Contact elements

60 and 61 are bonded to housing 42 and are engaged, respectively, by

contacts

50 and 51.

Contacts

60, 61 and 50, 51 are connected, by appropriate lugs, to external sources of current.

Actuator 44 includes an insulating block 64, and

crossarms

67 and 68. Crossarm 67 contains an opening 69, a lower insulating surface 70, and a wedging surface 71, at its forward end which, as shown in FIG. 6, contains a conductive wedging portion 71a. Arm 68 is slightly shorter than arm 67 and contains an upper insulating surface 74, and an external wedging surface 76, which as shown in FIG. 6, contains conductive wedging portion 76a. The nonconductive remainder of

surfaces

70, 71, 74, 76 are made of resilient material.

In operation, as actuator 44 is moved in the direction of the arrow in FIG. 4, which contacts 50 and 60 engaging, wedging surface 71 bears against contact 50 separating it from contact 60 electrical continuity between

contacts

50 and 60 being maintained for the moment through insert 71a. In the course of this travel, element 40 is driven through its unstable center position and it snaps away from insert 71a to the position shown in FIG. 5. Further travel of actuator44 causes insulative surface 70 on the under side of arm 67 to bear on contact 50 pressing contact 51 against contact 61. Arm 68 is sized to allow contact 51 to engage contact 61 clear of wedging surface 76. When actuator 44 is moved in the return direction, wedging surface 76 bears on contact 51 separating it from contact 61. Element 40 is thus driven back through its overcenter position and snaps back to the position shown in FIG. 4, where contact 50 engages contact 60 through opening 69. Further travel of actuator 44 causes surface 74 on the upper side of arm 68 to bear on contact 51 pressing contact 50 against contact 60.

The separation of

contacts

50, 51 from

contacts

60, 61 respectively, caused by wedging

surfaces

71, 76, respectively, is slow compared to the separation of

contacts

50, 51 from wedging

surfaces

71, 76, respectively, caused by the snapping of element 40. Thus, for DC current, the preferable fast separation is accomplished by the use of conducting inserts 71a, 76a.

Of course, for switching alternating current, where a slow separation or break of contacts is desirable (for if the current passes through zero, as it does twice each cycle, while the contacts are separating, arcs between the contacts will be extinguished) conductive inserts 71a and 76a are omitted and replaced with insulative material, as shown in FIG. 5. This embodiment achieves slow break and snap action make of the contacts. It should be noted that the return" movement of actuator 44 might be merely further movement of the actuator in the same direction if the actuator valve were mounted for rotary, rather than straight-line movement.

FIG. 7-9 show a snap action switch and portions thereof also having an insulated housing 42 with a snap member 40 mounted, as shown in FIGS. 4 to 6. Actuator 84 contains an insulating block 85, having bonded therein resilient metallic wedging

arms

86, 87, each arm having an opening 88, defining

bridges

89, 90, respectively. Insulated cam-shaped

lifting ears

91, 92 are an integrally molded part of housing 42.

In operation, as the actuator is moved in the direction of the arrow in FIG. 8, bridge 89 of arm 86 wedges between

contacts

50 and 60 and forces the contact overcenter causing contact 51 to engage contact 61. Further travel causes bridge 89 to be driven downward by camming ear 91, until bridge 89 disengages from contact 60, and, with further movement and camming action, reengages contact 50 pressing it downwards to trap the

contacts

51 and 61 together. Reverse movement accomplishes the reverse effect with bridge 90 and camming car 92.

Again, in this embodiment, as in FIGS. 4 to 6, resilient metallic wedging

arms

86, 87 connect

contacts

50 and 60, and 51 and 61 respectively, until snap-over occurs. However, when

arms

86 and 87 are cammed by

cars

91, 92 respectively, contact with

contact surfaces

60, 61 is broken before

contacts

50, 51 are engaged. As with the previous embodiment, wedging

arms

86, 87 may be coated with an electrical insulating material where slow contact break is desired. Fast break can also be achieved by making

camming ears

91, 92 out of conducting material, connected, respectively, to contact sur faces 60, 61, and insulating

arms

86, 87.

Other embodiments will occur to those skilled in the are and are within the following claims.

We claim:

1. A snap action switch comprising a snap acting member having a first electrical contact connected to a first terminal and capable of being actuated by pressure applied through the contact itself, means mounting said said snap acting member in a neutral condition in the manner that said snap member tends to remain stable on either side relative to an unstable position, a stationary second electrical contact connected to a second terminal and adapted to be engaged by said first contact when said snap member is in a first stable position, and a wedging member mounted for sliding movement along said stationary second contact from a first position spaced from said first contact in the direction of said sliding movement to a second position between said first and second contacts upon application of an actuating force, said wedging member being of sufficient thickness to push said first contact away from said stationary second contact until said snap member snaps through said unstable center position, thereby to cause said first contact to snap to its second stable position, said wedging member including at least a leading edge of electrically conductive material engageable with both said first and second contacts with initial sliding movement of said wedging member to maintain electrical contact between said first and said second contact until said snap member snaps through said unstable center position, and means for causing said first contact to snap back to said second contact.

2. The device of claim 1 wherein said means for causing said first contact to snap back against said second contact comprises a second wedging member and a stationary third electrical contact, connected to a third electrical terminal and mounted to be engaged by said first contact when when said snap member is in said second stable position, said second wedging member mounted for sliding movement along said stationary third contact from a first position spaced from said first contact in the direction of said sliding movement to a second position between said first contact and said third contact, and being of sufficient thickness to push said first contact away from said stationary third contact until said snap member snaps through said unstable center position, said second wedging member including at least a leading edge of electrically conductive material engageable with both said first and third contacts with initial sliding movement of said second wedging member to maintain electrical contact between said first contact and said third contact until said snap member snaps through said unstable center position, said second wedging member including an electrically conductive portion positioned to maintain electrical contact between said first contact and said third contact until said snap member snaps through said unstable center position.

3. A snap action switch comprising a snap-acting member having a first electrical contact, connected to a first electrical terminal, and capable of being actuated by pressure applied through the contact itself, means mounting said blade in a neutral condition in the manner that said snap member tends to remain stable on either side relative to an unstable position, a stationary second electrical contact, connected to a second electrical terminal adapted to be engaged by said first contact when said snap member is in its first stable position, a stationary third electrical contact, connected to a third electrical terminal adapted to be engaged by said first contact when said snap member is in its second stable position, and an actuating structure mounted for movement relative to said first contact comprising first and second wedging members, located between said stationary contacts, said first wedging member being located to move from a first position spaced from said first contact in the direction of movement to slide into a second position between said first contact and said second contact with movement of said actuating structure in one direction to push said first contact to snap away from said second contact and against said third contact, and said second wedging member being located to move from a first position spaced from said first contact to slide into a second position between said first contact and said stationary third contact with return movement of said actuating structure in the opposite direction to push said first contact to snap away from said third contact and against said second contact, said wedging members spaced apart from each other in the direction of movement of said actuating structure so that only one of said wedging members is located between said first contact and a stationary contact during said snapping movements.

4. The device of claim 3 wherein at least one said wedging member includes a leading electrically conductive portion in order to maintain electrical contact between said first contact and a corresponding stationary contact until said snap member snaps through said unstable center position.

5. The device of claim 3 wherein at least one of said wedging members includes a trailing portion of electrical insulating material arranged to press said first contact firmly against said stationary contact after said snap movement.

6. The device of claim 3 wherein said wedging members slide along said stationary contacts and are of sufficient thickness to push saidsnap member through said unstable center position upon movement to a position between said first contact and one said stationary contact.

7. The device of claim 3 wherein said wedging members are of insufficient thickness to push said snap member through said unstable center position, and wherein said device includes at least two stationary camming members, one member projecting from, adjacent each said stationary contact toward the other said stationary contact and aligned with said first contact, each said cammingmember having a surface tapering toward the other stationary contact in the direction of movement of said actuating structure, said surface located to be slidingly engaged by one of said wedging members upon movement of said actuating structure, and projecting toward said other stationary contact sufficiently for said wedging member to push said first contact through said unstable center position toward said other stationary contact upon said sliding engagement.

8. The device of claim 7 wherein each said wedging member comprises a wire having a longitudinal axis lying parallel to the corresponding stationary contact and perpendicular to the path of movement of said actuating structure.

9. The device of claim 8 wherein said actuating structure comprises an insulating block, a first wire secured in said block extending along one said stationary contact, and having a right angle bend adjacent said first contact to form said first wedging member, and a second wire secured in said block and insulated from said first wire by said block, extending along the other said stationary contact, and having a right-angle bend oppositely adjacent said first contact to form said second wedging member.

10. The device of claim 9 wherein at least the portions of said wires constituting said wedging members are electrically conductive.

11. The device of claim 7 wherein each said camming member has a surface tapering toward said other stationary contact in the direction of movement of said actuating structure, and said surface has .a maximum tapered portion sufficient to press said first contact against other stationary contact when said wedging member is between said maximum tapered portion and said first contact.

12.,The device of claim 3 wherein said stationary contacts are parallel, planar, opposed conductive members,.said actuating structure moves in a direction parallel to said contacts, and each said wedging member comprises a wire having a longitudinal axis parallel to said stationary contact, and perpendicular to the path of movement of said actuating structure.

Claims

6. The device of claim 3 wherein said wedging members slide along said stationary contacts and are of sufficient thickness to push said snap member through said unstable center position upon movement to a position between said first contact and one said stationary contact.

7. The device of claim 3 wherein said wedging members are of insufficient thickness to push said snap member through said unstable center position, and wherein said device includes at least two stationary camming members, one member projecting from, adjacent each said stationary contact toward the other said stationary contact and aligned with said first contact, each said camming member having a surface tapering toward the other stationary contact in the direction of movement of said actuating structure, said surface located to be slidingly engaged by one of said wedging members upon movement of said actuating structure, and projecting toward said other stationary contact sufficiently for said wedging member to push said first contact through said unstable center position toward said other stationary contact upon said sliding engagement.

11. The device of claim 7 wherein each said camming member has a surface tapering toward said other stationary contact in the direction of movement of said actuating structure, and said surface has a maximum tapered portion sufficient to press said first contact against other stationary contact when said wedging member is between said maximum tapered portion and said first contact.

12. The device of claim 3 wherein said stationary contacts are parallel, planar, opposed conductive members, said actuating structure moves in a direction parallel to said contacts, and each said wedging member comprises a wire having a longitudinal axis parallel to said stationary contact, and perpendicular to the path of movement of said actuating structure.