US2970857A

US2970857A - Magnetic door latch

Info

Publication number: US2970857A
Application number: US673972A
Authority: US
Inventors: Herbert D Squire
Original assignee: MIDWEST Manufacturing Co
Current assignee: MIDWEST Manufacturing Co
Priority date: 1957-07-24
Filing date: 1957-07-24
Publication date: 1961-02-07
Anticipated expiration: 1978-02-07

Description

UnitedV States. Patent MAGNETIC DOOR LATCH Herbert D. Squire, Galesburg, Ill., assignor to Midwest Mfg. Company, Galesburg, Ill.

Filed July 24, 1957, ser. No. 613,912

6 claims. (ci. 292-2515) This invention relates to latches for refrigerator doors and more particularly to a magnetic door latch.

Although magnetic latches have been proposed for refrigerator doors there have been certain difficulties in connection with the operation thereof which the present invention overcomes. One of the problems in connection with such a door latch is the fact that a door gasket is interposed between the door and the cabinet and the seal of the door depends upon a full contact of the gasket, which is carried by the door, being engaged with the cabinet adjacent the door opening. Due to the irregularities in the door construction, the gasket must often be compressed more at one point than another, and usually there is some compression of the gasket throughout its full linear length which requires considerable holding pressure. As is well known, to those versed in the art, the greatest holding power exerted by a magnet is attained when the llux path is closed by the magnetic part which is termed a keeper. Heretofore the gasket tended to hold the keeper away from the magnet and made it necessary to slam the door in order for the keeper to engage the magnet. Similarly the greatest effort to break the keeper loose from the magnet occurred atthe start, and, should the magnet be strong enough and powerful enough to hold the'door closed against the pressure exerted by the gasket it required a relatively complicated means to break the holding power upon opening the door. Furthermore such adjustments as were necessary to adjust the magnet in proximity to the keeper of the door were relatively complicated and difcult to make.

By the present invention I have provided a magnetic latch wherein the magnet will attract the keeper without the need for slamming the door, and wherein a greater holding power may be realized and still enable the door to be opened relatively easily. By the present invention the shocks against the magnet due to closing of the door are reduced to a minimum. The mechanism is very simple, easy to install and easy to adjust for proper holding power.

Still other objects of the invention and the invention itself will be apparent from the following description of an embodiment thereof, which description is illustrated by the accompanying drawings and forms a part of this specification.

In the drawings:

Fig. 1 is a vertical medial section of a door latch of my invention, the cabinet and door -being shown in fragment.

Fig. 2 is a view taken on the line 2-2 of Fig. 1.

Fig. 3 is a view of the latch in the process of opening the door; and Y Fig. 4 is a view similar to Fig. l of a modification thereof.

Briey, the invention constitutes a magnetic means secured to the cabinet, and a keeper means pivotally carried by the door and arranged to be attracted by the llux of the magnetic means when the door is in a closed position, and a lever means is used to tilt the keeper means about its pivot to cause the release of the keeper means from the magnetic nx.

As best shown in Figs. 1 and 2 a door 10 is provided opposite to a cabinet 11, the door being provided with the usual inturned ange 12 and the cabinet with a similar flange 13. The meeting face of the door and cabinet are each provided with openings 15 and 16. The opening 16 in the cabinet receives a receptacle 20 which may be of generally rectangular formation and is provided with a flange 21 for enabling it to be secured to the door by screws. The receptacle provides a housing for the magnetic member which includes a pair of magnets 23 that can be of any permanent magnetic material, of which there are many on the market today, the magnets being secured to a circuit bar 24. The magnets are preferably provided with openings 25 to receive loosely the heads of screws 26 which extend slidably through the circuit bar 24 and are threaded into the bosses 27 in the base of the receptacle. The receptacle is also provided with one or more projections 29 each of which provides a holder for a spring or springs 30 interposed between the bottom of the receptacle and the magnet means. The magnets and the circuit bar are covered by a thin non-magnetic casing 32, which may also hold them together although the circuit bar and magnets could be held together as a unit by other means such as cementing.

The magnetic means is held outwardly by the spring 30 and may be adjustably moved inwardly or outwardly by threading the screws 26 inwardly or outwardly. Thus, the position of the magnet means relative to the base of the cabinet may be adjusted and, when adjusted beyond the base of the cabinet, will automatically move inwardly because of the aforesaid connection. A similar receptacle 40 is secured in the opening of the door, preferably being provided with an open back and having bosses 41 on either of its sides. A keeper 42 is pivotally secured to the boss 41 by a pin 43 and preferably comprises a channel shaped member having a forward wall for engagement with the magnet means and side walls forthe reception of the pin 43. The keeper may be pivoted freely on the pin 43 as best shown in Fig. 3.

Also secured to the s'ide walls of the receptacle 40 by a pin 45 is a keeper operating lever 46. In the construction shown, this is a bell crank shaped lever having an end 46a for connection to an operating rod 47 which extends up and is connected to a door handle, not shown, in any approved manner. The other end of the bell crank lever is provided with a cam surface 4Gb. It will be noticed that the cam surface is constructed along the lines of radii which progressively increase in length from the pivot pin outward. Thus in the position shown in Fig. l a relatively great lever action is realized by the cam which bears against the inner face 42a of the keeper, which pressure tends to move the keeper about its pivot 43 as the bell crank is moved above its pivot 45. vThis enables the holding action to be broken off, though great, because of the leverage obtained. As the keeper is tilted however the cam rolls on the face of the keeper to the position shown in Fig. 3 where a greater movement of the keeper is realized at a time when the holding power of the magnet is decreased because the flux path is broken. Fig. 3 shows the device at the point where the flux path is suciently broken with the pulling pressure on the handle that will enable the door to be moved to an open position.

As previously stated the position of the magnet must be coordinated with the thickness of the gasket and the pressure required to compressthe gasket by adjusting the screw 26 inwardly or outwardly to allow the magnetic means to be moved inwardly or outwardly against the pressure of spring 30. It is also apparent that should the door be slammed there is no danger of breakage of the magnets, which are normally very brittle, because they are held within the casing 32 and the whole unit under such conditions moves inwardly against the pressure of the spring 30.

A very important feature of the invention is illustrated in Fig. 3. It will be noted that the structure is such as to hold the keeper in position shown when the door has opened. That is the weight of the keeper being outside of the pivot point causes the keeper to tilt outward at its upper end. Under these conditions the keeper being tilted, the door can be moved gently towards a closed position and since the end of the keeper then projects beyond the plane defined by the door gasket so that it may contact the magnetic means, a flux path is immediately established which causes the door to be drawn into the position shown in Fig. l without the need for slamming the door.

Although the cam shown in Figs. 1 to 3 inclusive is of the preferred form, it is also contemplated that other shapes and lecatons for the cam may be provided as shown in Fig. 4. In this instance the cam lever 60 is pivoted at 61 on a pivot point spaced below that of pivot point 43 for the keeper 42. The operation is substantially the same as that described, except that should the tilting action be desired a light spring may be used to effect the same.

Having thus desiribed my invention I am aware that numerous and extensive departures may be made therefrom without departing from the invention as defined in the appended claims.

I claim:

l. A magnetic door latch for holding a door member in closing position against a cabinet member formed with a door opening comprising a magnet carried by one of said members, a keeper pivotally connected to the other member and arranged to provide a closed circuit flux path for the magnet when the door is closed, a keeper operating lever pivotally supported spaced from the pivot of the keeper and formed with a cam surface for engagement with the keeper and a lever arm, said cam surface being formed with a surface close to the pivot point of the keeper and lever and a continuation of said surface extending away from said pivots whereby upon rocking of said lever a greater mechanical advantage is exerted at the start to break the keeper from the fiux path and a greater movement is realized after the flux path is broken for moving the keeper farther from the flux path.

2. A magnetic door latch for holding a door member in closed position over a door opening in a cabinetmember comprising a magnet secured to one of said members, a keeper pivotally secured to the other member and in position to provide a flux path for the magnetic flux of the magnet when the door is closed, a keeper tilting member for rotating the keeper about its pivot to break it from the flux path to the magnet comprising a lever pivotally connected to the same member as the keeper and having a curved face the radii of which increase progressively in the direction away from the pivot points of the keeper and the lever, and means' for rotating the lever about its pivot.

3. A magnetic door latch for holding a door member in closed position over a door opening in a cabinet member comprising an elongated magnet secured to one of said members, an elongated keeper pivotally secured spaced from its ends to the other member and in position to provide a flux path for the magnetic flux of the magnet when the door is closed, a keeper tilting member for rotating the keeper about its pivot to break it from the flux path to the magnet comprising a lever pivotally connected to the same member as the keeper and having a curved face the radii of which increase progressively in the direction away from the pivot' points of the keeper and the lever, and means for rotating the lever about its pivot.

4. The latch of claim l, wherein there is provided resilient means biasing the magnet toward the keeper, and adjustable means limiting the extent to which the magnet is biased toward the keeper by said resilient means.

5. Means for releasably holding a door member closed over a door opening in a cabinet member and for compressing a deformable gasket mounted therebetween to form an air tight seal comprising: a magnet mounted on one of said members; a keeper pivotally mounted on the other of said members, said keeper occupying a first angular position in which it is substantially wholly within the magnetic field of said magnet when said door member is closed, and a second angular position in which it is partially in the magnetic field of said magnet when said door member is open sufciently to release the pressure on a substantial portion of said deformable gasket; cam means actuatable for pivotally moving said keeper from said first angular position to said second angular position to effect opening of said door member; and means for maintaining said keeper' in said second angular position while said door member is open.

6. Means for releasably holding a door member as set forth in claim 5 wherein upon closure of said door member said means for maintaining said keeper in said second angular position is overcome as said keeper enters into partial magnetic engagement with said magnet, and wherein said magnet is effective when said keeper enters into partial magnetic engagement therewith to draw said keeper into said first angular position in substantially full magnetic engagement with said magnet thereby compressing said deformable gasket and effecting closure of said door member.

References Cited in the file of this patent UNITED STATES PATENTS 2,240,035 Catherall Apr. 29, 1941 2,514,927 Bernhard July 11, 1950 2,693,382 Teetor Nov. 2, 1954 2,801,870 Davey Aug. 6, 1957 2,864,637 Teague et al. Dec. i6, 1958 2,871,676 Miller et al. Feb. 3, 1959