Magnetic Latch

Abstract

A magnetic latch has a pair of substantially coextensive permanent bar magnets which can be arranged for mutual attraction positioning to maintain a hinged member in a closed position. One of the magnets is made axially movable with respect to the other so as to assume a mutual repulsion position with the other which will enable the magnets to assist in opening the hinged member. The movable magnet is actuated by a manually operable member such as a lever bar mounted on a pivot on which manually actuated bars are also mounted to enable the movable magnet to be positioned by manual operation of the actuating bars. A biasing spring to reduce the force necessary to be applied to move the magnet is also provided.

Description

Magnetic latches have been used on hinged members such as kitchen cabinets and refrigerators for many years. In a typical structure a permanent magnet is positioned on the door and a plate is positioned on the body of the refrigerator or cabinet where it will make contact with the magnet when the door is closed. The magnetic attraction of the magnet for the plate then maintains the door in closed position. In the alternative, the magnet may be positioned on the body of the hinged member and the plate on the movable portion or door.

While magnets to maintain doors in closed position have proved to be very satisfactory they have one disadvantage. The magnet holds the plate very strongly when the door is in the closed position but as contact is broken and the door opened the magnetic attraction of the magnet for the plate diminishes very rapidly. Thus, considerable initial force must be exerted to break the grip between the magnet and plate. In some cases the use of both hands is necessary and breaking contact between the magnet and plate can impart quite a jar to the contents of the box.

SUMMARY OF THE INVENTION

This invention is directed to a magnetic latch which uses magnetic attraction to maintain a door member in closed position and in addition uses magnetic repulsion to aid in opening a door member. The latch has a pair of substantially coextensive permanent bar magnets which can be arranged in a mutual-attraction position to maintain a door in closed position. One of the magnets is axially movable with respect to the other so as to place the magnets in a mutual-repulsion position and the resulting magnetic force will then assist in opening the door. The magnets may be selectively positioned to attraction or repulsion position by a manually operable member such as a lever bar mounted on a pivot on which manually actuated bars are also mounted. A biasing spring to reduce the force needed to position the magnets for mutual repulsion is a desirable feature of the invention.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 of the drawing is a schematic diagram illustrating a refrigerator door equipped with the magnetic latch of this invention. In FIG. 1 the magnets are arranged so as to hold the door in closed position.

FIG. 2 is similar to FIG. 1 except that the magnets are positioned to produce a repulsion effect and help to open the door.

FIG. 3 illustrates an alternative arrangement for manually moving one of the magnets.

FIG. 4 illustrates the same pivot-lever arrangement for moving one of the magnets as FIGS. 1 and 2 but includes a hand hold for convenience in opening the door.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1 and 2 of the drawing illustrate the application of the present invention to a refrigerator. The refrigerator consists of a stationary body portion 10 shown in fragmentary form which has a hinged door 11. Between the body 10 and door 11 is a gasket 12 which serves to seal the contents of the refrigerator when the door 11 is closed. Fixedly positioned with respect to the body 10 is a ferrite multiple strip magnet 13 mounted upon a soft steel return path element 14 which is in turn mounted upon the refrigerator body 10. A ferrite multiple strip magnet 15 coextensive with the magnet 13 but with converse polarity is mounted upon a soft steel return path element 16 which is slidably mounted on the door 11 for reciprical vertical movement in the view shown. The magnets 13 and 15 and their respective return elements 14 and 16 form magnetic assemblies in parallel axial alignment. The polarity of the magnets 13 and 15 is indicated by the letters "N" and "S". It is to be understood that a reversal of the polarity indicated in FIGS. 1 and 2 will not change the operation of the device.

The return path element 16 has an extended portion 16A which includes an aperture 16B. The portion 16A serves to anchor a biasing tension spring 17. The aperture 16B accommodates a lever bar 18 which is fastened to a pivot 19 rotatably mounted on the front of the door 11. A pair of manually operable rotating bars 21 and 22 are also mounted on the pivot 19 spaced about 120.degree. from lever bar 18 and about 120.degree. from each other.

FIG. 1 shows the latch in its closed position. In this position the poles of the magnets 13 and 15 are aligned in a mutual-attraction relationship, thereby creating a force to hold the door in closed position. FIG. 2 illustrates the position of the magnetic assemblies at the start of the opening cycle. The magnet 15 and its return path element 16 have been moved vertically downward by downard movement of the lever bar 18 which was, in turn, actuated either by pushing the actuating bar 21 or pulling the actuating bar 22. Some of the poles of the magnet 13 are now adjacent similar poles on the magnet 15. The repulsion force between the magnets 13 and 15 will now exert an opening force on the door 11. This force is quickly reduced as the gap between the magnets 13 and 15 widens but it has served the purpose of breaking the tenacious grip of the magnets illustrated in FIG. 1 without a jolt or a jar.

The lever bar construction shown in FIGS. 1 and 2 provides satisfactory operation to the latch but the actuating bars 21 and 22 can catch on the clothing of people who pass too close to the refrigerator. Since the magnets are positioned near the edge of the door the actuating means can be mounted outside the seal and go around the door edge as illustrated in FIG. 3. In this embodiment a manually operable member 24 is fixedly attached to a rigid bar 25 which is, in turn, fixedly attached to the return element 16. The door is opened by manually pushing the element 24 downward and then pulling it after the door has opened slightly. The element 24 is not so likely to catch the clothing of persons passing near the refrigerator as are the actuating bars 21 and 22.

In order to reduce the likelihood that the actuating bars 21 and 22 will snag clothing and further to strengthen these elements, a hand hold 26 may be provided as illustrated in FIG. 4. With this structure the hand hold 26 may be grasped and pushed upwards slightly in order to disengage the door and thereafter the hand hold may be used to pull the door 11 the rest of the way open. This structure has the advantage that an opening force exerted directly outward on the hand hold 26 will tend to restore the magnet 15 and return element 16 for use in closed position where the biasing spring 17 is omitted.

In order to provide easy operation it is important that the magnet 15 be freely movable with respect to the magnet 13. Ideally, the magnets 13 and 15 should be slightly out of engagement in order to reduce friction to a minimum. The gap between the two magnets, however, must be kept very small as both the attraction and repulsion forces are reduced very rapidly with an increase in the gap. The biasing spring 17 must have sufficient tension to enable the magnets 13 and 15 to be positioned as illustrated in FIG. 2. Yet the spring 17 must allow the magnets to return to their FIG. 1 position as soon as the door is closed.

While the magnets 13 and 15 have been described as ferrite multiple strip magnets it is obvious that other magnets would be satisfactory for use in this invention. For example, alnico magnets and magnets of a cobalt-rare earth type could be used. While magnets having a bar or flat configuration are desirable other configurations that allow one of the magnets to be movable with respect to the other would be feasible. Similarly, magnets with a single north and single south pole could be used satisfactorily. Thus, while the invention has been described with reference to certain specific embodiments, it is obvious that there may be variations which fall within the proper scope of the invention. Accordingly, the invention should be limited in scope only as may be necessitated by the scope of the appended claims.

Claims

What I claim as new and desire to secure by letters patent of the United

1. A magnetic latch comprising: a first and second magnetic assembly, each of said magnetic assemblies comprising a permanent magnet having an inner and an outer surface along its axis; a return path element contacting each of said magnets along its outer surface, the two magnetic assemblies being positioned so that the inner surfaces of the magnets face each other, one of said magnetic assemblies being axially movable and said permanent magnets being magnetized in a transverse direction with respect to their axes with the polarity of the magnets alternating along their axes so as to produce a transverse magnetic circuit path across said first and second assemblies when they are positioned in magnetic interaction relationship therebetween; and means for axially moving said movable magnetic assembly

2. The magnetic latch assembly of claim 1 in which the moving means is a

3. The magnetic latch of claim 2 in which the lever mechanism includes a lever bar mounted on a pivot, said axially movable assembly being movable by said lever bar, and a pair of manually actuated bars, also mounted on

4. The magnetic latch assembly of claim 2 in which there is a spring mechanism to bias the axially movable assembly so that like poles on the

5. The magnetic latch of claim 4 in which the first magnetic assembly is attached in fixed position to a closure member and the second magnetic assembly is attached in axially movable position to a door member.