US2781216A - Magnetic door latch - Google Patents

Description

Feb- 12, 1957 T. P. FOLEY MAGNETIC DooR LATCH Filed oct." 4,. 1955 INVENToR. THOMAS P. FOL EY lax/ H l S ATTORNEY United States Patent() MAGNETIC DOOR LATCH Thomas l. Foley, Louisville, Ky., assignor to General Electric Company, n corporation of New York Application October 4, 1955, Serial No. 538,410

4 Claims. (Cl. 292-2515) The present invention lrelates to magnetic latches for doors and is more particularly concerned with magnetic latches for refrigerator cabinets and' the like having relatively heavy doors which must be held in a closed position relative to the cabinet.

Refrigerator cabinets ordinarily include a relatively heavy door and gasket adapted to encircle the access opening of the cabinet for sealing the gap between the door and the cabinet when the door is in the closed position. In order to effect sufficient compression of the gasket to secure a satisfactory seal, a latch mechanism capable of exerting a rather high compressive force on the gasket is required. When a magnetic latch is used for this purpose, a relatively powerful magnet must be employed. Except when such a magnet is in actual contact with the armature element forming part of the magnetic latch, the magnetic field in the area surrounding the magnet is of high intensity with the result that the spring of a watch when brought into a position adjacent the magnet may be magnetized to such an extent as to damage the watch.

It is an object of the present invention to provide a simple and low cost magnetic latch including a permanent magnet and means for shorting the magnet and thereby decreasing both the area and the intensity of magnetic field when the magnet is not in contact with its cooperating armature.

A further object of the invention is to provide an improved magnetic latch including a housing or support for the permanent magnet component designed to prevent accidental contact with the magnet when the magnet is out of contact with its cooperating armature.

Further objects and advantages of the invention will become apparent from the following description and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming part of the application.

In carrying out the objects of the present invention, there is provided a magnetic door latch or catch which is particularly adapted for holding a refrigerator door member in closing relationship with the refrigerator cabinet member. The latch comprises a permanent magnet and a non-magnetic housing for the magnet which supports the magnet on one of the two members. A cooperating arrnature adapted to be secured to or form a part of a surface portion of the other of the members cooperates with the magnet to hold the door in a closed position. The housing includes a recess in which the permanent magnet is loosely disposed. The recess is formed in part by opposed sloping side walls so that it is generally wider at the bottom thereof than at the top or open side. By this configuration, a magnet having substantially the same cross-sectional shape as the recess is capable of limited movement within the recess but is retained therein by the converging side walls. An auxiliary armature or keeper is provided on the opposite side of the bottom wall of the housing from the magnet and this keeper causes the magnet to be attracted towards the bot- 2,781,216 Patented Feb. 12, 1957 tom wall of the housing during all times when the magnet is out of contact with the principal armature. By the arrangement the working face of the magnet is contained within the recess during such periods and the keeper of soft magnetic material effectively prevents damage to watch springs or other items of this nature which the user of the refrigerator may inadvertently bring into the area adjacent -to the permanent magnet.

For a better understanding of the invention reference may be had to the accompanying drawing in which the single figure is a sectional view of a refrigerator cabinet including an embodiment of the present invention.

Referring to the drawing there is shown a portion of the latching side of the usual household refrigerator including a cabinet comprising an outer wall 1 and a liner or inner wall 2, the liner 2 forming a food storage compartment within the cabinet. The outer wall 1 and the liner 2 are shaped to provide an access opening to the storage compartment at the front of the refrigerator and a breaker strip 3 of heat insulating material closes the space between the wall 1 and the liner 2 in the region of the access opening. A door 4 for closing the access opening includes an outer wall 5 and a spaced inner wall 6 which may be formed of a suitable heat insulating material such as a plastic material. The door 4 is supported by suitable hinges (not shown) on the outer wall 1 of the cabinet and is adapted to swing on these hinges so as to open and close the access opening to the storage compartment. A gasket 7 extending entirely around the access opening suitably secured to the door serves to seal the space between the door and the face 8 of the cabinet when the door is in the closed position as shown in Fig. l.

In order to secure the door in its closed or closing position and to compress the gasket 7 into sealing relationship with face portion 8 of the cabinet, there'is provided a magnetic latch including a permanent magnet 11 and a cooperating armature 12. The armature 12 composed of soft magnetic material is attracted to and held in engagement with the permanent magnet 11 when the door 4 is in its closed position and serves to secure the door in that position and to compress the gasket 7.

Means for supporting the permanent magnet 11 on the inturned flange 13 forming part of the outer wall 5 of the door comprises a non-magnetic housing 14 suitably secured to the ange 13 as by means of screws 15. This housing comprises a bottom wall 16 and converging side Walls 18 and 19 which cooperate to form a generally trapezoidal recess in which the magnet 11 is loosely disposed. As is shown in Fig. l of the drawing the magnet 11 has substantially the same cross-sectional shape as the recess 20 but is somewhat smaller than the recess so that it is capable of limited movement within 4the recess between the full line position in which its side walls are in contact with the side walls 18 and 19 and the dotted line position in which it is in contact with the bottom wall 16 of the recess 20.

When the door 4 is in its closed position, it is held in spaced relationship with the ange 8 forming part of the cabinet structure by contact of the gasket 7 with the flange 8. Under these circumstances, the working face 22 of the magnet extends forwardly from the housing to contact the armature and the magnet is retained in the recess by contact thereof with the converging side walls 18 and 19. Insofar as the magnetic field is concerned, the magnet is effectively shorted by the armature 12 and the magnetic path is substantially restricted to the armature 12. However when the door is opened to obtain access to the refrigerator storage compartment, contact between the magnet 11 and the armature 12 is broken so that the magnetic field is no longer restricted to the armature 12. Under such conditions and in the absence of some means for restricting the field when the door is in its open position any magnetizable material such .as a watch spring brought into the area adjacent the permanent magnet may become magnetized. To avoid this danger there is provided an auxiliary armature or keeper for .restricting the magnet eld when the door is open. The auxiliary armature or keeper is preferably provided lin the form of a plurality of shims 24 and 25 some 'or all of which are composed of a magnetic material such as magnetic sheet steel and which serve the dual purpose of shorting the magnet 1l when the door is open and of providing the proper adiustment of the magnet 1l and its housing 14 relative to the cabinet face portion 3. These shims are positioned between the door ange 13 and the bottom wall i6 of the housing 14, or in other words on the opposite side of the `bottom wall from the magnet 1i, so that the non-magnetic bottom wall 16 provides an air gap between the magnet 11 and the shims. When the refrigerator door is opened, the magnetic attraction between the magnet l1 and the keeper is sutcient to cause the magnet to move to a position in contact with the bottom wall lr6 so that the entire magnet including its working face 22 is recessed below the face 23 of the housing 14. There is therefore less likelihood of magnetizable articles worn by the user of the refrigerator from coming into direct contact with the magnet 11. Also in this position the magnet is effectively shorted by the keeper so the magnetic field is substantially .restricted to the keeper.

Ey providing an air gap between the magnet Ill and the keeper comprising the shims 24 and 25 which is greater than any gap between the principal armature 12 and the face 22 of the magnet when recessed in the recess 20 with the door in its closed position, movement of the magnet ll into engagement with the armature 3.2 is assured when the refrigerator door is closed assuming that the keeper and the armature l2 have the same permeability characteristics. When dierent materials are used for the armature l2 and the shims 24 and 25, the desired action of the magnet 11 can be obtained by substituting non-magnetic shims for some of the magnetic shims so that the vattractive forces between the magnet and the armature l2 will always be greater than between the magnet and the keeper assembly.

From the foregoing description, it will be evidentythat there has been provided a low cost but powerful or strong magnetic latch which includes effective means for holding the magnet external energy to a harmless intensity when the magnet is not in Contact with the latching armature. While separate keeper and armature elements have been shown, it will be obvious that when `the outer wall 1 of the cabinet or the outer wall 5 of the door or both are composed of magnetic materials such as magnetic sheet steel the portions of the ange 8 of the cabinet outer wall and the flange 13 of the door outer wall may respectively serve as armature and keeper elements.

While there has been shown and described a particular embodiment of the present invention, it will be obvious to those skilled in the art that various changes and modifications may be made without depart-ing from the invention, and it is intended by the appended claims to cover all sach changes and modifications which fall within the true spirit and scope of the invention.

What i claim as new and desire to secure by Letters Patent of the United States is:

l. A magnetic door latch for holding a door member .in closing relation with a cabinet member, .said latch comprising a permanent magnet and a non-magnetic housing for supporting said magnet on one of said members, a cooperating armature adapted to form a surface portion of the other of said members and to be contacted by said magnet when said door member is closed, said housing including a bottom wall and opposed upwardly converging side walls, said 4magnet being loosely disposed in said housing and including side walls adapted to be engaged by the walls of said housing to retain said magnet in said housing and limit the forward movement of said magnet away from said bottom wall, and a keeper on the opposite side of said bottom wall from said magnet and being adapted to cause said magnet to be attracted towards said bottom wall when out of Contact with said armature.

2. A magnetic door latch for holding a door member in closing relation with a cabinet member, said latch comprising a permanent magnet and a non-magnetic housing for supporting said magnet on one of said members, a cooperating armature adapted to be secured to the other of said members and to be contacted by said magnet when said door member is closed, said housing including a bottom wall and opposed upwardly converging side walls forming a trapezoidal recess, said magnet being of sub stantially the same general shape as said recess and being loosely disposed in said recess and including side walls adapted to be engaged lby said converging side walls of said housing to retain said magnet in said housing and limit the forward movement of said magnet away from said bottom wall, and a keeper' on the opposite side of said bottom wall from said magnet and being adapted to cause said magnet to be attracted towards said bottom Wall when out `ot" contact with said armature.

3. A magnetic latch tor holding a door member in closing relation with a cabinet member, said latch comprising a permanent magnet and a non-magnetic housing for supporting said magnet on one of said members, a cooperating armature adapted to be secured to the other of said members and to be contacted by said magnet when said door member is in closing relation with said cabinet member, said housing having a recess therein which is generally wider at the bottom thereof than at the top, said magnet having substantially the same cross-sectional shape as said recess and being loosely disposed in said recess for limited movement between a first position in Contact with the bottom wall of said recess and a second position in which the face of said magnet protrudes from said recess and is retained therein by contact with the side walls of said recess, a keeper adjacent said housing and on the opposite side of the bottom wall of said recess from said magnet, the magnetic characteristics of said keeper and said armature being so proportioned that said magnet is attracted to said first position by attraction toward said keeper when said door member is open and is attracted to said second position in Contact with said armature when said door member is in closing relation with said cabinet.

4. A magnetic latch of claim 3 in which the cross-sectional shapes of said recess and said magnet are trapezoidal and said magnet is a bar magnet.

Ellis July 5, 1949 Teetor Sept. 28, 1954

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