US2896043A

US2896043A - Electric switch formed from magnets

Info

Publication number: US2896043A
Application number: US639512A
Authority: US
Inventors: Lewis D Andrews
Original assignee: Stackpole Carbon Co
Current assignee: Stackpole Carbon Co
Priority date: 1957-02-11
Filing date: 1957-02-11
Publication date: 1959-07-21
Anticipated expiration: 1976-07-21

Description

United States Patent ELECTRIC SWITCH FORMED FROM MAGNETS Lewis D. Andrews, St. Marys, Pa., assignor to Stackpole Carbon Company, St. Marys, Pa., a corporation of Pennsylvania Application February 11, 1957, Serial No. 639,512

10 Claims. (Cl. 200-87) This invention relates to electric switches, and more particularly to those formed from magnets.

It is among the objects of this invention to provide an electric switch which is of extremely simple design, which is easy to assemble, which does not contain any springs, which snulfs the are between the contacts when the switch is opened, and in which the contact surfaces rub against each other when the switch is opened and closed.

In accordance with this invention, the switch includes a stationary magnet and a movable magnet which nor-, mally are attracted to each other. Means are provided for moving the movable magnet along the stationary magnet from one predetermined position to another. Projecting from the inner surface of one magnet is a pair of electric contacts, while a layer of conducting material on part of the inner surface of the other magnet bridges those contacts only when the movable magnet is in one of the two positions just mentioned. The magnets themselves are formed from a material which is a non-conductor of electricity, and each magnet is provided with a plurality of north and south poles. In each of the two positions of the movable magnet referred to above, unlike poles of the two magnets are opposite each other to attract the magnets toward each other. On the other hand, while the movable magnet is moved from either of its positions to the other, like poles of the magnets are opposite so-that the movable magnet will be repelled from the stationary magnet during that movement. In other words, as the movable magnet travels from one of its positions to the other, it also moves away from the stationary magnet.

The invention is illustrated in the accompanying drawings, in which:

Fig. 1 is a side view, partly in central se'ction, of a rotary switch closed;

Fig. 2 is a plan view thereof;

Fig. 3 is a side view rotated 90 from Fig. 1 and showing the upper magnet halfway between the open and closed positions of the switch;

Figs. 4 and 5 are exploded diagrammatic views showing the magnets in switch-closed and switch-open positions, respectively;

Figs. 6 and 7 are views corresponding to Figs. 1 and 2 of a linear switch;

Fig. 8 is a longitudinal section of the modification showing the upper magnet halfway between open and closed positions of the switch; and

Fig. 9 is a diagrammatic view, similar to Fig. 4 of the modification.

Referring to Figs. 1, 2 and 3 of the drawings, a pair of annular magnets 1 and 2, preferably of the same size and shape, are disposed face to face in superimposed relation. The lower or stationary magnet 1 may be secured to an insulating base plate 3 of larger diameter by means of the electric contacts 4, with which the base magnet is provided. When only two contacts are used, they generally are located, 180 apart. Each one extends through the magnet and projects slightly from its upper 2,896,043 Patented July 21, 1959 "ice surface. The lower ends of the contacts extend through holes in the base plate and are fastened securely to terminal members 5, which engage the bottom of the plate to hold the adjoining magnet down on it.

Extending down through both magnets is a center post 7, the lower end of which is rigidly mounted in the base plate. The post projects a short distance above a top insulating plate 8, which may have the same diameter as the magnets and is rigidly secured in any suitable manner.

to the top magnet. The upper end of the center post is provided with a head 9 normally spaced from the top plate. The top plate and top magnet can turn on the post and also slide up and down on it.

To rotate the top magnet on the stationary base magnet, a lever 11 extends across the top plate above the center post and has one end pivotally mounted on the upper end of a pin 12 that extends down beside the magnets and has its lower end secured in the base plate. The opposite end of the lever is provided with a longitudinal slot 13 that slidably receives a vertical stud 14, which is anchored in the top plate. The lever may be provided with a pair of upwardly projecting ears 15 for receiving an actuating member (not shown), by which the levercan be swung back and forth in an arc of a predetermined number of degrees, preferably about When the lever is swung in this manner, it will move the stud laterally and thereby turn the top magnet on the center post from one extreme position to another.

The bottom or inner surface of the top magnet is partially coated with a layer of conducting material 17, such as silver. This layer does not extend all the way around the magnet, but far enough to bridge the two contacts 4 when the top magnet is in one of its two extreme positions, as shown in Figs. 1, 2 and 4. In the other position, indicated in Fig. 5, the space between the ends of the conducting layer is above one of the contacts, so they will not be bridged by the layer and the switch therefore will be open.

The two magnets are non conductors of electricity, because they are made from ceramic material that can be magnetized. Such material is well known in the magnet art. These magnets can also be magnetized in such a way as to provide each of them with several north and south poles. With circular magnets, as shown, each pole forms a segment of the circle. These are illustrated diagrammatically in Figs. 4 and 5. Preferably, each magnet has four north and four south poles which, of course, alternate circumferentially around the magnet. The magnets are so positioned relative to each other that in either of the two positions of the top magnet 90 apart, its north poles will be opposite to the south poles of the base magnet. Consequently, in both of those positions the magnets will be attracted strongly toward each other. When the switch is in closed position, the conducting layer 17 on the top magnet will be drawn tightly against both contacts 4 on the base magnet. When the top magnet has been turned 90 to the position indicated in Fig. 5, it will still be drawn against the base magnet, but the conducting layer will not touch one of the contacts, because that contact will be located in the gap between the ends of the layer.

As the top magnet is turned from either of its two positions (Fig. 4 or Fig. 5) toward the other, its north poles will move across the north poles of the base magnet, with the result that the top magnet will be repelled and will slide up the post until top plate 8 engages the head of the post, as shown in Fig. 3. As the top magnet is turned farther, its north poles will again start to move across the south poles of the base magnet and the two magnets will be drawn together.

It will therefore be seen that during rotation of the top magnet from one position to the other, it is repelled from the base magnet and turns freely without sliding against it except at the beginning and end of the rotation. The sliding engagement at both ends of the movement of the top magnet is desirable, because it rubs the electric contact surfaces together and thereby helps to keep them clear. When the magnets separate or come together, it is done quickly, thereby providing quick make-and-break. No springs are required for this switch, because the magnetic forces take their place. Construction of the switch is therefore simplified. A great advantage of this switch is that when the conducting layer 17 is separated from the fixed contacts, the are that otherwise would tend to form is snuffed out, due to the separating surfaces being in a magnetic field. This reduces wear of the contacting surfaces and transfer of material between them.

Although the rotatable magnet has been referred to herein, for the sake of convenience, as the top magnet, it will be understood that the switch is the same, regardless of its position.

In the modification shown in Figs. 6 to 9 the switch operates in a straight line instead of in an arc. The stationary or base magnet 20 is rectangular and secured to an insulating base plate 21 by electric contacts 22 that project slightly above the magnet. A channel-shape metal housing 23 of wellknown form has the lower edges of its side walls secured to the base plate. Disposed between those walls and slidable lengthwise thereof is an upper rectangular magnet 24 that is secured in any suitable manner to the bottom of an upper insulating plate 26 normally spaced from the top of the housing 23. This plate is provided with an integral actuating button 27 projecting from it up through a longitudinal slot 28 in the top of the housing. The bottom of the top magnet has a predetermined area covered with a conducting layer 29, such as silver.

The two magnets are made of the same non-conducting material as those in the first embodiment. Also, they are magnetized in such a way as to provide each of them with several north and south poles. The poles alternate with each other, and each extends across a magnet, as indicated in Fig. 9. When button 27 is at the end of the housing slot shown in Fig. 6, conducting layer 29 bridges the two fixed contacts because the north poles of the top magnet are opposite the south poles of the bottom magnet and the two magnets are therefore drawn toward each other. As the button is moved toward the opposite end of the slot, it carries the north poles of the top magnet above like poles below it, with the result that the magnets repel each other so the top magnet is forced up against the top of the housing, as shown in Fig. 8. As the button approaches close to the left-hand end of the slot, north poles are again moved above south poles and the top magnet is then attracted to the bottom one. In its new position, the conducting layer 29 will lie at the left of the fixed contacts, as viewed in Figs. 6 and 9, and the switch will be open. This linear or straight line switch has the same advantages as the one described first.

According to the provisions of the patent statutes, I have explained the principle of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. An electric switch comprising a stationary magnet and a movable magnet normally attracted to each other, the movable magnet being separable from the stationary magnet and also movable laterally along it, means for moving the movable magnet laterally along the stationary magnet from one predetermined position to another, a

pair of electric contacts projecting from the inner surface said two positions, said magnets being nonconductors of electricity and each provided with a plurality of north and south poles, unlike poles of the two magnets being opposite each other in each of said two positions to attract the magnets toward each other, and like poles of the magnets being opposite each other while the movable magnet is moving laterally from either of said positions to the other, whereby the movable magnet will be repelled from the stationary magnet during said movement.

2. An electric switch according to claim 1, in which said movable magnet is rotatable relative to the stationary magnet, and the north and south poles of each magnet are spaced circumferentially around the axis of rotation of the movable magnet.

3. An electric switch according to claim 2, in which said magnets are circular and coaxial, and a pivot pin projects rigidly from the center of one magnet and is slidably and rotatably mounted in the center of the other magnet.

4. An electric switch according to claim 1, in which the movable magnet is reciprocable linearly relative to the stationary magnet, and the north and south poles of each magnet are spaced lengthwise thereof.

5. An electric switch comprising a base magnet, a pair of electric contacts projecting from the top of the magnet, a top magnet above the base magnet and movable vertically relative thereto, means for turning the top magnet between two predetermined positions, relative to the base magnet, and a layer of conducting material on part of the bottom of the top magnet bridging said contacts only when the top magnet is in one of said two positions, said magnets being nonconductors of electricity and each provided with a plurality of circumferentially spaced north and south poles, unlike poles of the two magnets being opposite each other in each of said two positions to attract the magnets toward each other, and like poles of the magnets being opposite each other while the top magnet is turning from either of said positions to the other, whereby the top magnet will be repelled from the base magnet during rotation.

6. An electric switch according to claim 5, including a pivot pin projecting from the top of the base magnet, the top magnet being slidably and rotatably mounted on said pm.

7. An electric switch according to claim 5, in which said turning means includes a lever extending across the top of the top magnet, means pivotally mounting one end of the lever on a vertical axis beside the magnets, the opposite end of the lever being provided with a longitudinal slot, and a pin projecting from the top of the top magnet up into said slot, whereby when the slotted end of the lever is swung back and forth it will cause the pin to turn the top magnet.

8. An electric switch comprising a base magnet, a pair of electric contacts projecting from the top of the magnet, a top magnet above the base magnet and movable vertically relative thereto, means for reciprocating the top magnet linearly between two predetermined positions, and a layer of conducting material on part of the bottom of the top magnet bridging said contacts only when the top magnet is in one of said two positions, said magnets be ing nonconductors of electricity and each provided with a plurality of north and south poles, unlike poles of the two magnets being opposite each other in each of said two positions to attract the magnets toward each other, and like poles of the magnets being opposite each other while the top magnet is moving linearly from either of said positions to the other, whereby the top magnet will be repelled vertical from the base magnet during said movement.

9. An electric switch comprising a housing, a base magnet rigidly mounted in the bottom of the housing, a pair of electric contacts projecting from the top of the magnet, a top magnet in the housing above the base magnet and slidably engaging the sides of the housing, the top of the housing normally being spaced from the top magnet, means for moving the top magnet lengthwise of the case between two predetermined positions, and a layer of conducting material on part of the bottom of the top magnet bridging said contacts only when the top magnet is in one of said two positions, said magnets being nonconductors of electricity and each provided with a plurality of north and south poles, unlike poles of the two magnets being opposite each other in each of said two positions to attract the magnets toward each other, and like poles of the magnets being opposite each other while the top magnet is moving lengthwise from either of said positions to the other, whereby the top magnet will be repelled from the base magnet toward the top of the housing during said movement.

10. An electric switch comprising a stationary magnet and a movable magnet normally attracted to each other, the movable magnet being separable from the stationary magnet and also movable laterally along it, means for moving the movable magnet laterally along the stationary magnet from one predetermined position to another, a pair of stationary electric contacts associated with the stationary magnet, a bridge of conducting material carried by References Cited in the file of this patent UNITED STATES PATENTS 2,298,573 Little Oct. 13, 1942 2,498,683 Hubbell Feb. 28, 1950 2,543,014 Grace Feb. 27, 1951 2,548,581 Bigelow Apr. 10, 1951 2,604,561 Simon July 22, 1952 2,742,537 Leslie Apr. 17, 1956 2,770,697 Kellett Nov. 13, 1956