US3472975A - Electrical switches with plural breaks - Google Patents

Description

Oct. 14, 1969 .1. E. SORENG ETAL ELECTRICAL SWITCHES WITH PLURAL BREAKS 2 Sheets-Sheet 1 FIG. 2

Filed May 29, 1967 FIG.

I N Vf N TORS John E. Sor

Oct. 14,1969 ESQRENG ETAL 3,472,975 I ELECTRICAL SWITCHES WITH PLURAL BREAKS Filed May 29, 1967 C 2 Sheets-Sheet 2 I FIG. 3 F

x 36 2a 4 2 32 3 G J United States Patent ELECTRICAL SWITCHES WITH PLURAL BREAKS John E. Soreng, Eugene, Greg, and Jesse M. Cobb, Glenview, Ill., assignors to Inrlak Manufacturing Corp.,

Northbrook, 11]., a corporation of Illinois Filed May 29, 1967, Ser. No. 641,920 Int. Cl. H01h 15/06 US. Cl. 20016 9 Claims ABSTRACT OF THE DISCLOSURE An electrical switch having a contactor with either a linear or a rotary movement, a first contact point or plate for supplying electrical current to the contactor, a plurality of additional contact points or plates positioned for substantially simultaneous engagement by the contactor, and means elecrically connecting said additional contact points or plates together, whereby the additional contact points or plates establish a plurality of parallel circuits with said contactor, all of said circuits being broken upon disengagement of said contactor from said additional points or plates, so that the wear and erosion due to arcing is distributed among said additional points or plates.

This invention relates generally to electrical switches and is applicable with particular advantage to switches for automotive or other similar services.

Many switches basically comprise a supporting member, a contactor movable relative to the supporting member along a pre-determined path, a contact member or other means on the supporting member for supplying electrical current to the contactor, and an additional contact member on the supporting member, positioned for engagement by the contactor, to make and break the circuit controlled by the switch. The repeated making and breaking of the circuit causes wear and erosion of the contactor and the contact member with which it is engageable. Most of the erosion is due to the arcing which tends to occur when a circuit is broken by the disengagement of the contactor from the contact member. Eventually, such erosion may become so extensive as to impair the operation of the switch.

In accordance with the present invention, the contactor is engageable with and disengageable from a plurality of additional contact members which may be in the form of points, plates, segments or the like. All of the additional contact members are connected together electrically so that they establish a parallel circuit with the contactor. The disengagement or" the contactor with all of the additional contact members is substantially simultaneous, so that all of the parallel circuits .are broken. With this construction, the erosion, due to arcing when the circuits are broken, is distributed among the contact members, so that the useful life of the switch is greatly prolonged. It has been found that the erosion is self-equalizing. It is virtually impossible to achieve absolutely simultaneous breaking of the circuits. Thus, the arcing occurs at the contact member which is the last to be disengaged by the contactor. Such arcing causes erosion which eventually delays the break at this contact member, so that another contact member becomes the last to be disengaged by the contactor. The arcing then shifts to such other contact member. In his way, the arcing is shifted to all of the contact members which are involved in the plural breaks.

It will be recognized that the present invention is particularly advantageous for switches which are subjected to a great many cycles of making and breaking circuits. An example of such a switch is the stop light switch on .an automobile which is cycled whenever the brake pedal is operated. The plural break switches of the present inice vention have greatly prolonged operating life and thus are especially well suited for such services.

Further objects and advantages of the present invention will appear from the following description taken with the accompanying drawings, in which:

FIGS. 1, 2, and 3 are top, end and side views of a normally closed push button switch to be described as the first illustrative embodiment of the present invention.

FIG. 4 is an elevational view of the contact supporting member and the contacts thereon, taken generally as indicated by the line 44 in FIG. 1.

FIG. 5 is an elevational view of the switch with the contact supporting member removed, the view being taken generally along the line 55 in FIG. 1.

FIG. 6 is a perspective view of the contactor for the switch of FIGS. l-5.

FIG. 7 is a longitudinal section, taken generally along the line 77 in FIG. 3.

FIG. 8 is a transverse section, taken generally along the line 8-8 in FIG. 7.

FIG. 9 is a view similar to FIG. 5, but showing a second embodiment in the form of a normally open pushbutton switch.

FIG. 10 is an elevational view of the contact supporting member and the contacts for the switch of FIG. 9.

FIG. 11 is a diagrammatic illustration of the switches of FIGS. 1-10.

FIG. 12 is a diagrammatic illustration showing the extension of the principles of the present invention to switches having three or more contact members which are simultaneously disengageable by the contactor.

FIG. 13 is a diagrammatic view of a rotary switch constituting another embodiment of the present invention.

With reference to FIGS. 1-8, the invention will be seen in the form of a normally closed push-button switch 20,

which is suitable for use as the stop light switch of an automobile. Externally, the switch 20 comprises a casing 22, an operating push-button 24, and a pair of terminals in the form of lugs or prongs 26 and 28. The two wires or leads of the circuit to be controrlled by the switch are connected to the terminals 26 and 28. When the pushbutton 24 is not depressed, the circuit between the terminals 26 and 28 is closed by the switch. Depressing the push-button 24 opens the circuit. The casing 22 is shown as being made of metal and rectangular in shape. A mounting bracket 30 is secured to the casing 22.

For automotive stop light service, the switch 20 is positioned so that the push-button 24 is depressed by the brake pedal or some other movable element of the brake system, when the brake pedal is not operated. Thus, the stop light circuit is open. When the brake pedal is operated, the push-button 24 springs outwardly to close the stop light circuit.

The internal construction of the switch 20 is shown in FIGS. 58. It will be seen that the switch 20 comprises a contact supporting member 32 and contactor means, illustrated as comprising a contactor 34- which is movable relative to the member 32. The movement of the contactor 34 can be either linear or rotary, but in this case it is linear. Thus, the contactor 34 is mounted on a carriage 36 which is slidable along a linear path within the casing 22. The push-button 24 is formed integrally with the carriage 36 and projects outwardly through an opening 38 in an end wall 40 of the casing 22. The carriage 36 is guided by side walls 42, 44, and 46 of the casing 22.

The carriage 36 is preferably biased to its initial position by a spring 48. As shown, the spring 48 is compressed between an end wall 50 of the casing 22 and an opening or socket 52 in the carriage 36. To insure that the contactor 34 will travel with the carriage 36, the contactor is formed with a plurality of tabs or lugs 54 which project laterally therefrom, and are slidably received in slots or openings 56, formed in the carriage 36. The illustrated contactor 34 is plate-like in form and is preferably made of sheet metal. The ends of the contactor 34 are shown as being curled or bent to form rounded ramp portions 58. As shown in FIG. 7, the carriage 36 is preferably formed with ribs or ridges 60 and 62, with a recess or slot 64 therebetween. The contactor 34 is adapted to be positioned in the recess 64, with the ramps 58 adjacent the ribs 60 and 62.

The contactor 34 is preferably biased toward the contact supporting member 32 by a spring 66, illustrated as being compressed between the contactor and an opening or socket 68 in the carriage 36. The spring 66 also biases the carriage 36 against the side wall 46 of the casing 22.

Means are provided to supply electrical current to the contactor 34. Such means are illustrated as comprising a contact point or member 70 which is slidably engaged with the contactor 34. The contact member 70 may assure various forms but it is illustrated as the spherically rounded head of a rivet 72. It will be seen that the rivet 72 extends through a suitable opening in the contact supporting member 32 and is employed to secure the terminal 26 to the member 32. As shown, the supporting member 32 is in the form of a plate or board made of insulating material. The member 32 closes one side of the casing 22 and is suitably secured thereto.

In accordance with the present invention, the contactor 34 is movable into substantially simultaneous engagement with a plurality of additional contact points or members 74. Two of the contact points 74 are employed in the illustrated construction, but three or more could be employed. The contact points 74 could assume various forms but are illustrated as comprising the spherically rounded heads of rivets 76 which extends through suitable openings in the supporting member 32 and are employed to secure the terminal 28 to the supporting member. It will be seen that the terminal 28 is effective to connect the two contact points 74 together electrically. Thus, the contact points 74 establish parallel circuits with the contactor 34.

To provide for smooth operation of the contactor 34, the supporting member 32 is preferably formed with insulating bosses or points 78 which are slidably engageable by the contactor, when it is not engaging the contact points 74. Thus, the illustrated switch has two of the insulating bosses 78, spaced toward the contact point 70 from the contact point 74. The insulating bosses 78 preferably take the form of semi-perforations, which are punched, molded, or otherwise formed from the insulating material of the supporting member 32.

It may be helpful to summarize the operation of the switch 20, as shown in FIGS. 1-8. Initially, the spring 48 biases the carriage 36 to a position in which the contactor 34 engages the contact points 74, as well as the contact point 70. Thus, the circuit between the terminals 26 and 28 is closed. The contact points 74 establish parallel circuits with the contactor 34.

When the push-button 24 is pressed, the contactor 34 is moved out of engagement with both contact points 74, at substantially the same time. Thus, both parallel circuits are broken so that the circuit between the terminals 26 and 28 is opened.

The double break action provided by the two contact points 74 greatly prolongs the life of the switch because the erosion due to arcing is automatically distributed between the two contact points, and the corresponding portions of the contactor 34. This distribution of the erosion is illustrated to best advantage in FIG. 11, in which the eroded areas on the contactor 34 are shown at 80. Although the contactor 34 breaks with the contact points 74 at approximately the same time, it is virtually impossible to provide absolutely simultaneous breaking of the two parallel circuits. Thus, at any particular time, the arcing will be concentrated at the particular contact point 74 which is the last to break with the contactor 34.

Eventually, this arcing erodes the contactor 34, the contact points 74, or both, to such an extent that the other contact point 74 will become the last to break with the contactor. The arcing then shifts to the other contact point 74. In this way, the arcing alternates back and forth between the two contact points 74. This alternating break action insures that the erosion will be distributed between the parallel contact points.

FIGS. 9 and 10 illustrate a modified switch which is the same as the switch 20 except that the contact points 70 and 74 are relocated on the supporting member 32, so that the switch will be normally open. Thus, the spring 48 biases the carriage 36 to an initial position in which} the contactor 34 engages the contact point 70 but not the contact points 74. When the push button 24 is depressed, the contactor 34 is moved into engagement with contact points 74 at substantially the same time. When the pushbutton 24 is released, the contactor 34 breaks with the contact points 74 at approximately the same time. However, the break action is not absolutely simultaneous so that the arcing is concentrated initially at one of the contact points 74. After erosion occurs to a sufiicient extent, the arcing shifts to the other contact point 74 so that the erosion due to arcing is equalized. Thus, the provision of the two contact points 74 virtually doubles the useful life of the switch.

FIG. 11 also illustrated a circuit for either of the switches 20 and 90. As shown, one side of the battery 92 is connected to the terminal 28, and thence to the points 74. The other side of the battery 92 is grounded. One side of the load 94 is connected to the terminal 26, and thence to the contact points 70, which engages the contactor 34. The load 94 is shown as a solenoid but may comprise stop lights and other devices.

FIG. 12 illustrates an extension of the present invention to a switch having three or more of the parallel contact members 74. The contactor 34 is adapted to make and break simultaneously with all of the contact members 74. Here again, the break action is not absolutely simultaneous so that it actually occurs at one or another of the contact points 74. The resulting erosion due to arcing causes the break action to shift periodically to another of the contact points 74, so that the erosion is equalized. The useful life of the switch is generally proportional to the number of parallel contact points 74 which are pro:

vided.

FIG. 13 illustrates the invention as applied to a rotary switch 120. In this case, the switch comprises a contactor 134 which is movable along a circular path. The contactor 134 is mounted on a rotary carriage 136, indicated diagrammatically. The contactor 134 is engageable with a stationary contact member and also with a pair of stationary contact members 174. The engagement between the contactor 134 and the contact members 174 is substantially simultaneous, so that there is a double make and break action, as in the case of the previously described switches. The contactor 134 is engaged with the contact member 170 when the make and break occur between the contactor and the contact members 174. Thus, the break action is between the contactor.134 and the contact members 174. A terminal member 128 is provided to connect the contact members 174 together electrically. Thus, the contact members 174 establish parallel circuits with the contactor 134.

In the switch of FIG. 13, the contact members 170 and 174 are plate-like in form and segmental in shape. The contactor 134 is shown as being generally triangular in shape. The illustrated contactor 134 is formed with a contact point 134a which is engageable with the contact segment 170. The contactor 134 also has two other contact points 13419 which are engageable with the contact segments 174.

The areas of erosion are indicated at 180. The break between the contactor 134 and the contact segments 174 is not absolutely simultaneous, with the result that the arcing is concentrated at one of the contact segments. Eventually, the erosion proceeds to such an extent that the arcing is shifted to the other contact segment 174. Thus, the erosion due to arcing is automatically distributed.

By virtue of the present invention, the erosion due to arcing can be distributed so that the effective life of the switch can be greatly prolonged. This important advantage is achieved with very little increase in the size, complexity, or cost of the switch.

Various other modifications, alternative constructions and equivalents may be employed, as will be understood by those skilled in the art.

We claim:

1. In an electrical switch,

the combination comprising a casing having one wall providing a supporting insulator,

stationary conductive contact means mounted on the inner side of said insulator,

movable conductive contact means disposed in said casing opposite said stationary conductive contact means,

means for moving said movable contact means in said casing along a path on said inner side of said insulator and into and out of engagement with said stationary contact means,

and terminal means for supplying electrical current to said movable contact means,

one of said contact means comprising a contact plate having one side facing the other contact means,

said other contact means having a plurality of duplicate conductively unified contact points located for simultaneous engagement with and disengagement from different edge portions of said plate on said one side thereof to distribute the erosion of said contact plate and said contact points due to current interruption.

2. The combination of claim 1,

said movable conductive contact means comprising said contact plate,

said stationary conductive contact means comprising said contact points.

3. The combination of claim 1,

said movable conductive contact means comprising said contact points,

said stationary conductive contact means comprising said contact plate.

4. The combination of claim 1, said terminal means comprising a stationary contact element slidably engaging said movable conductive contact means.

5. The combination of claim 1, in which said path of said movable conductive contact means is linear.

6. The combination of claim 1, in which said path of said movable conductive contact means has a circular curvature.

7. In an electrical switch,

the combination comprising a casing,

a plate-like insulator comprising one wall of said casa carriage movable in said casing along a path parallel to the inner side of said insulator,

a conductive contactor plate mounted on said carriage and facing said inner side of said insulator,

a feeder contact point mounted on said insulator and projecting inwardly therefrom into sliding engagement with said contactor plate to supply electrical current thereto,

and a plurality of duplicate conductively unified contact points mounted on said insulator and projecting inwardly therefrom for sliding engagement with said contactor plate,

said duplicate contact points forming duplicate parallel closure paths when said contactor plate is engaged with said duplicate contact points,

said duplicate contact points being disposed at corresponding locations along the path of said contactor plate so that different edge portions of said contactor plate are simultaneously disengageable with said duplicate contact points to distribute the erosion of said contactor plate and said contact points due to current interruption.

8. The combination of claim 7, including a conductive plate on said insulator for conductively unifying said duplicate contact points.

9. The combination of claim 7, including spring means between said carriage and said contactor plate for biasing said contactor plate toward said contact points and said insulator.

References Cited UNITED STATES PATENTS 1,473,212 11/1923 Davis 200l6XR 3,174,000 3/ 1965 Golbeck 20016XR 3,238,318 3/1966 Bleibtreu et al 200-10 3,246,101 4/1966 Caputo 200--16XR ROBERT K. SCHAEFER, Primary Examiner M. GINSBURG, Assistant Examiner US. Cl. X.R. 200-11,

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