US 3691490 A
A magnetic electric switch comprising a sealed body of electrical insulating material forming a cavity, fixed contact members having one end located within said cavity and the other end located exteriorly of said body, a movable contact plate located within said cavity to electrically connect the ends of said fixed contact members located within said cavity and stationary magnetic means located within said body spaced from said cavity and from said movable contact plate to exert a magnetic force on said movable contact plate to pull said plate into contact with said fixed contact members.
Claims available in
Description (OCR text may contain errors)
United States Patent Ragni [451 Sept. 12, 1972 MAGNETIC SWITCH APPARATUS  Luigi Ragni, Brescia, Italy  Oxford Electric Corporation, Pittsburgh, Pa.
Filed: June 15, 1971 Appl. No.: 153,369
Foreign Application Priority Data Nov. 9, 1910 Italy ..5235A/70 u.s. Cl. .....33s/20s Int. Cl. ..H0lh 36/00 Field of Search 335/205, 206, 207
 References Cited UNITED STATES PATENTS I 3,040,146 6/1962 lmmeletaln ..335/205X 3,487,346 12/1969 Gardeletal ..335l205 Primary Examiner-Roy N. Envall, Jr. Anorney-William H. Webb et al.
 ABSTRACT fixed contact members.
7 Claims, 3 Drawing Figures lniiniiiiei ianillli PA'IENTEnsEm I972 3.691.490
nv VEN TOR. Luigi Ragni HIS AT TORNE Y5 MAGNETIC SWITCH APPARATUS This invention relates to switch apparatus and more particularly to a magnetically actuated sealed switch for opening and closing an electric circuit.
Many devices such as refrigerators, freezers and automobiles include a lamp for illuminating the interior when the door is opened. A circuit including the lamp is completed by a switch which is actuated when the door is opened, and when the door is closed, the switch opens the circuit. Push button and lever type switches are presently used for this purpose, but both types are expensive and have a number of disadvantages. For example, these mechanical switches often fail because of dust and moisture on the contact surfaces. Additionally, the contact surfaces corrode preventing consistent and long term operation. Problems also occur in installation and replacement since these switches must be electrically insulated from the device in which they are used.
The novel magnetic switch of my invention has a sealed housing which eliminates dust, moisture and corrosion. The sealed housing is made of electrical insulating material, and, hence, my switch may be readily inserted into an appropriately sized opening in either the door or the door frame of the device in which the switch is incorporated without electrical insulation. A movable contact plate is located in a cavity formed within the housing to connect fixed contact members which are adapted for connection into an electric circuit. The contact plate is moved relative to the fixed contact members by a stationary magnet sealed within the body and an exterior magnetic means. It is readily apparent that my novel magnetic switch has a number of advantages over mechanical switches. Since my switch is a sealed unit of electrically insulating material, it is not subject to corrosion, or interference by dirt and moisture, and may be quickly installed.
In the accompanying drawings, I have shown a preferred embodiment of my invention in which:
FIG. 1 is a section through theswitch in the closed circuit position;
FIG. 2 is a section through the switch in the open circuit position and including an exterior magnetic means; and
FIG. 3 is a section on line Ill-III of FIG. 2.
Referring to the drawings, it will be seen that the switch comprises a sealed body 1 made of a plastic or other rigid electrical insulating material and having a U-shaped cavity formed therein. A portion of fixed electric contact members 2 and a movable contact plate 4 are located within the cavity. Fixed contact members 2 are threadedly engaged with body 1 and have slotted ends so that they can be easily adjusted relative to the body. The outer ends of fixed contact members 2 are shown connected to wires 3 which form a part of a circuit including a lamp (not shown). Movable contact plate 4 is dimensioned to physically connect the ends of fixed contact members 2 to complete the circuit.
A rectangular cavity 6 is also formed within body 1 and is located between fixed contact members 2. A stationary permanent magnetic member 5 is located within cavity 6 and is physically separated from fixed contact members 2 and from movable contact member 4 by a wall 7 which is a part of body 1. Plat 4'is moved to connect fixed contact members 2 by the magnetic attraction of the stationary magnetic member. Magnetic member 5 has sufficient magnetic force to draw contact plate 4 toward it and to hold the plate firmly against the ends of contact members 2 to complete the circuit even though wall 7 separates magnetic member 5 from the movable plate.
As best shown in FIG. 3 of the drawings, each end of movable contact plate 4 is formed with a slot 8, and spheres 9 are mounted in recesses in the end walls of body 1 so as to extend into the cavity. The slots are centered in the movable contact plate, and the spheres are positioned centrally of the end walls. The spheres cooperate with slots 8 and maintain the movable contact plate in alignment during movement. While spheres are shown in FIG. 3, it should be understood that guide members having other shapes may be used in conjunction with slots in the movable contact plate. Regardless of the exact shape of the guide members and the slots, it is important that the movable contact plate is maintained in proper alignment to prevent binding during movement.
The detents shown at the ends of body 1 are used to hold the switch in position in a properly sized opening in either the door or the door frame of the device with which it is used. After wires 3 are connected to contacts 2 and the contacts are adjusted to properly position their ends within the cavity, the switch assembly is snapped into the opening. The detents are resilient and move toward each other as the switch is pushed into the opening. When the enlarged shoulders of the detents pass through the opening, they snap away from each other, and the ends engage the rear surface of the door or door frame. The forward surface of the door or the door frame is engaged by the upper and lower extensions at the ends of body 1.
The magnetic switch of my invention may be readily inserted into either the door or the door frame of such appliances as refrigerators, freezers and automobiles. It is necessary that the door or door frame which is to attract the movable contact plate have a magnetic sealing gasket or a magnetic insert positioned opposite to the switch. The member 10 in FIG. 2 is a portion of a magnetic gasket which will be attached to a door (not shown) to maintain it in the closed position, and when the door is closed, this gasket pulls the movable contact plate away from fixed contact members 2 against the force of stationary magnetic member 5. As will be apparent to those skilled in the art, the combination of my magnetic switch and the actuating magnet on the door or door frame of the device may form a magnetic latch to maintain the door in the closed position. In this instance, the switch performs the dual function of opening and closing a circuit to actuate an interior lamp and of maintaining the door in its closed position.
The operation of my device will be readily understood from a consideration of the drawings and the following brief description. Assuming that the switch is mounted in the door frame, when the door of the device is opened, the magnetic gasket or other magnetic insert on the door is moved away from the switch, and the movable plate is pulled into contact with the ends of fixed contact members 2 to complete the circuit and light the interior lamp. Alternatively, when the door of the device is closed, the portion of magnetic gasket 10 or other magnetic insert on the door opposite the switch pulls contact plate 4 away from fixed contact members 2 to open the circuit. As is apparent from the above description of the operation of my switch, the magnetic force of stationary magnetic member 5 is less than the magnetic force of the magnetic element on the door opposite the switch 5 so that when the door is closed, the magnetic element on the door attracts plate 4 to open the circuit.
My invention has important features including a sealed unit which can be easily snapped into place after the wires are connected and, hence, is not rendered inoperatively by dirt, moisture or corrosion. Additionally, the switch is inexpensive since housing 1 is made from plastic or other electrical insulating material and no mechanical members are included in the switch.
While the invention has been described for use in connection with refrigerators, freezers and automobiles, it will be understood that it may be used with any device wherein it is desired to have an interior lamp turned on automatically when a door is opened. Furthermore, it should be understood that the switch may be modified so that the switch completes the circuit when the door is closed and opens the circuit when the door is opened. This type of switch requires positioning the fixed contacts between the movable magnetic member and the wall of body 1 adjacent to the door.
While I have shown and described various embodiments of my invention, it should be understood that the invention may be otherwise embodied within the scope of the appended claims.
1. An electric switch of the type in which the electric circuit is normally open between spaced contact members having a sealed body formed of electrical insulating material, said body having a first cavity formed therein, contact members extending through said body with one end located within said first cavity and the other end located exteriorly of said body to receive wires of an electric circuit, a movable contact plate located within said first cavity dimensioned to contact and electrically connect the ends of said fixed contact members located within said first cavity and adapted to move toward and away from said fixed contact members to open and close the electric circuit, and stationary permanent magnetic means located within said body between said fixed contact members and spaced from said contact plate, whereby said stationary permanent magnetic means magnetically attracts said movable contact plate to connect said fixed contact members to close the electric circuit.
2. A switch as set forth in claim 1 wherein a portion of the length of each contact member is threaded to threadably engage said body, whereby said fixed contact members are adjustable relative to said body.
3. A switch as set forth in claim 1 including first guide means on said movable contact plate and second guide means carried by said body within said first cavity and aligned with said first guide means, said first guide means cooperating with said second guide means to retain said movable contact plate in alignment during movement.
4. A switch as set forth in claim 3 wherein said first giiide means are slots formed in the ends of said movae contact plate and said second guide means are spheres located in the end walls of said body and aligned with said slots, said spheres cooperating with said slots during movement of said movable contact plate.
5. A switch as set forth in claim 1 wherein a second cavity is formed within said body and said stationary permanent magnetic means is located in said second cavity and is separated from said movable contact plate by a wall integral with said body so that said movable contact plate cannot physically contact said stationary permanent magnetic means.
6. A switch as set forth in claim 1 including resilient detent members integral with the exterior surfaces of the end walls of said body, said detent members adapted to permit insertion of the switch into an opening formed in a structural member and to hold the switch in place in said member.
7. In a device having a frame and a closure member with magnetic means carried thereon, the improvement comprising an electric switch in which the circuit is normally open mounted in the frame in a location adjacent to the magnetic means on the closure member when the closure member is closed, said switch having a sealed body formed of electrical insulating material and carrying fixed contact members supported by said body, one end of each contact member located out of said body to receive electrical wires of the electric circuit and the other located within said body, a movable contact plate located within said body and adapted to contact and electrically connect the ends of said contact members located within said body, a stationary permanent magnet located within said body and adapted to attract said movable contact plate when said closure member is opened so that said movable plate contacts the ends of said contact members to complete the electric circuit including said contact members.