US3492037A - Magnetic touch latch - Google Patents

Description

United States Patent O U.S. Cl. 292-2515 Claims ABSTRACT OF THE DISCLOSURE A touch type latch for cabinet doors is provided in the form of a magnetic catch device adapted to be secured to a cabinet frame for cooperation with a metallic plate adapted to be secured to the cabinet door in a position to be magnetically held by the catch device. The catch device itself includes means for decreasing the magnetic field strength of one portion of the magnet holding the plate, this means being responsive to a touching pressure on the door so that the door is thus released and opened. The means for decreasing the magnetic field strength takes the form of a member having a high permeability for magnetic flux which member may 'be either a so-ft ferrous metal or a second permanent magnet, is normally at a spacing from the permanent magnet holding the plate. Touching pressure on the door decreases this spacing in such a manner that the member short circuits the flux magnet thereby decreasing its attracting power to the plate and releasing the door. Suitable coiled springs are included to assure positive separation once the magnetic field strength has been decreased and to further restore the movable members to their original positions preparatory to a subsequent operation of closing of the door.

This invention relates to touch latches and more particularly to a novel magnetic touch latch for use with cabinet doors.

BACKGROUND OF THE INVENTION Touch latches of the mechanical type are well known in the art. These devices generally include a catch device adapted to be secured to an inside frame portion of a cabinet for cooperation with a hook element secured to an inside surface portion of the cabinet door. When the door is closed, the hook element is received in the catch device so that the door is held closed. Opening of the door is accomplished by exerting a touching pressure on the exterior surface of the door in such a manner as to urge the hook element further into the catch device. This action results in a releasing of the hook element so that the door is freed to swing open.

Latches of the foregoing type are very popular in modern construction wherein it is desired that the exterior surface of a cabinet door be wholly free of any knobs, handles, or undercut recesses normally necessary in order to open and close the cabinet door.

While the aesthetic appearance of cabinet doors is greatly enhanced by such touch latches as noted above, there are encountered certain difficulties. These difficulties arise from the mechanical nature of the hook and latching mechanism therefor and are of two major types: first, in many instances the hook will fail to be retained in the catch mechanism secured to the cabinet frame such that the door will not positively remain closed. Second, the hook becomes properly engaged but the release mechanism responsive to touching pressure on the cabinet door fails to function with the result that the cabinet door is locked shut. This latter type of failure is most annoying and can only be corrected by unhinging the door or, if the hinges happen to be buried in the molding as is often the case. actuallv damaging the door itself.

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BRIEF DESCRIPTION OF THE INVENTION The present invention provides a novel magnetically operated touch latch having all of the advantages of prior mechanical type latches discussed heretofore but wherein the two major difficulties of failure to latch or unlatch are wholly eliminated.

More particularly, the invention contemplates a magnetiolatch device including a permanent magnet arranged to be secured to the frame of a cabinet for cooperation wi h a plate member secured to an inside surface of the door in a position to be magnetically attracted to the magnet. The magnetic latch mechanism itself further incorporates means for decreasing the magnetic field strength of the permanent magnet at the portion thereof attracting the plate in response to a touching pressure on the door urging the plate against the permanent magnet. With this arrangement, the magnetic holding power is reduced sufficiently to release the door in response to touching pressure so that the door is free to open.

In the preferred embodiment of the invention, the means for decreasing the magnetic field strength constitutes a member of high permeability normally positioned at a given distance from the permanent magnet. This member may comprise a soft ferrous metal or alternatively a second permanent magnet. The distance between the member and permanent magnet is decreased in response to touching pressure on the door such that the member short circuits the fiux of the permanent magnet thereby decreasing its field strength at its holding portion to the door plate. If the member takes the form of a second permanent magnet, it would, of course, be oriented to have its north and south poles reversed relative to the first mentioned permanent magnet. Hereafter, the phrase member of the high permeability is meant to include either a soft iron member or second permanent magnet.

The structure incorporates suitable spring means for assuring a positive separation of the door plate from the permanent magnet after the field has been weakened and for repositioning the movable parts to their normal spaced relationship preparatory to normal action when the door is again closed.

Since holding of the door in its closed position and releasing of the door depends solely on magnetic field strength, the two major problems discussed heretofore with respect to mechanical type push catches are substantially avoided. Moreover, the entire device incorporates only one moving part with the attendant advantage of simplicity and reliability.

BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of the invention will be had by now referring to a preferred embodiment as illustrated in the accompanying drawings, in which:

FIGURE l is a fragmentary perspective view of a cabinet structure with the cabinet door in open position and wherein the novel magnetic touch latch of this invention has been incorporated;

FIGURE 2 is a fragmentary cross section taken in the direction of thearrows 2 2 of FIGURE 1 and further illustrating the door in a Aposition immediately prior to complete closing;

FIGURE 3 is a cross section of the magnetic latch structure taken in the direction of the arrows 3-3 of FIGURE 2 showing the door in its completely closed position; and

FIGURE 4 is a cross section similar to FIGURE 2 illustrating the relative positions of the parts during the opening operation of the door.

DETAILED DESCRIPTION OF THE INVENTION Referring first to FIGURE 1, there is illustrated generally by the numeral 10 a cabinet having a frame portion or jamb 11 against which adoor 12 is arranged to be closed. The magnetic touch latch of the present invention includes amagnetic catch device 13 adapted to be secured to the frame 11 of the cabinet and aplate 14 adapted to be secured to an inside surface of thedoor 12 in a position to be magnetically attracted to thecatch device 13 when the door is in its closed position.

Referring now to the cross section of FIGURE 2, it will be noted that themagnetic catch device 13 includes first and second side plates of non-magnetic material such as plastic designated 15 and 16 disposed on either side of a holder formed of plastic and designated by the numeral 17. A member of highpermeable material 18 is held in theholder 17 with a forward portion projecting into the space between theside plates 15 and 16. This space between the side plates defines a channel having a forward open end facing outwardly from the cabinet or in the direction of the inside surface lof the door when the door is cl-osed. The'holder 17 andmember 18 constitute a fixed magnetic means and theside plates 15 and 16 define a guide channel.

Receivable in the foregoing described guide channel is a movable magnet means includingclips 19 and 20 of nonmagnetic material secured toside plates 21 and 22 of magnetic material defining forward and rearward pole pieces for apermanent magnet 23. Themagnet 23 is in the form of a block, the forward and rear ends of the si/"e plates 21 and 22 extending beyond the forward and rear surfaces of theblock 23 as shown. Theclips 19 and are dimensioned to lit within the channel between theside plates 15 and 16. In FIGURE 2, this channel is designated generally by the numeral 24.

With particular reference to FIGURE 3, there are provided first spring means in the form 0f coil springs 25 and 26 disposed in opposing bores formed in the clips andholder 17. These springs serve to hold themovable magnet 23 at a given distance relative to the fixed magnetic material in the form of themember 18. The Springs and 26 will be compressed when the.permanent magnet 23 is urged into the channel to decrease the spacing between the magnet and themember 18.

As also illustrated in FIGURE 3, there is provided a second spring means in the form of acompression spring 27 extending from a bore in the movable magnet means towards theplate 14 when thedoor 12 is in closed position. This latter spring will be placed under cornpression when theplate 14 is closed against the forward poles defined by theside plates 21 and 22 for themagnet 23.

FIGURE 4 illustrates the relative positions of themagnet poles 21 and 22 and magnetic material in the form of themember 18 when a touching pressure P is exerted on thedoor 12. Thus, in the position of FIGURE 4 it will be evident that when thedoor 12 is urged further inwardly, themember 18 will be received between the rear poles of theside plates 21 and 22 for themagnet 23. Because of the high permeability of themember 18, there will be provided a short circuit for the flux of the magnet through themember 18 thereby decreasing the magnetic field strength at the forward poles of theside plates 21 and 22. The second spring means 27 described in FIGURE 3 is of sufficient strength to overcome the small residual magnetic attraction of the pole pieces to theplate 14 when the magnetic field is decreased as described in FIGURE 4 so that thedoor 12 is then separated from theplate 14 after application of the touching pressure.

OPERATION The operation of the magnetic touch latch of this invention wlil be evident from the foregoing description. Initially, themagneitc catch device 13 illustrated in FIG- URE 1 is secured to the inside frame of the cabinet 11. This may be accomplished by providing suitable screw hole brackets on the member itself or alternatively simply embedding the member in the frame structure as illustrated. Theplate 14 is then held by a simple screw to the inside surface of thedoor 12 in a proper position to engage the forward poles of theside plates 21 and 22 when in closed position as illustrated by the dottedlines 12 in FIGURE 2.

When the cabinet door is completely closed, it will assume the dottedline position 12 illustrated in FIG-URE 2 and will be held closed by the magnetic field of the 'magnet 23 appearing across the front portions of theside plates 21 and 22. Because of the spacing between thepermanent magnet 23 and themember 18, maximum field strength will occur across the front poles so that proper holding of the door in its closed position will result. It should be noted that thesecond spring 27 of FIG- URE 3 will be compressed slightly when theplate 14 engages the front poles of theside plates 21 and 22. However, the attractive magnetic force is greater than the counterforce exerted by this spring so long as the spacing between themagnet 23 and themember 18 remains as shown in FIGURES 2 and 3.

Whenever it is desired to open the door, it is only necessary for a person to apply a slight touching pressure on the exterior of the door in the direction of the arrow P of FIGURE 4. This pressure will then urge themagnet 23,side plates 21 and 22 andclips 19 and 20 into thechannel 24 in such a manner that themember 18 will be received between the rear poles defined by theside plates 21 and 22; that is, in a position adjacent to thepermanent magnet 23. Because of the high permeability of themember 18, the flux will be short circuited through this member thereby greatly decreasing the magnetic field strength at the forward poles defined by theside plates 21 and 22. In fact, the magnetic field is sufiiciently weakened that thesecond spring 27 exerts a sufficient force against theplate 14 to readily separate it from the front poles of theside plates 21 and 22 so that the door is released.

In the foregoing operation, it will be understood that thefirst springs 25 and 26 of FIGURE 3 are compressed when the movable magnet means is received fully within the channel to the position illustrated in FIGURE 4. When the pressure P is released on thedoor 12, these first springs will tend to retract thepermanent magnet 23 and associatedclips 19 and 20 along with theside plates 21 and 22 from the channel. However, there will simultaneously be applied pressure to theplate 14 by thesecond spring 27. 'Ihe position of themember 18 between the rear poles of theside plates 21 and 22 short circuits the magnetic field for a period of time necessary for themember 18 to be completely withdrawn from between these plates and it is during this interval of time that thesecond spring 27 has an opportunity to effect the separation. Once the separation is made, -any residual magnetic attraction between the front poles of theside plates 21 and 22 and theplate 14 is further decreased because of the distance between theplate 14 and the poles; that is, the resulting small space upon initial separation. The operation is such that there is assured a positive separation of the door and an actual outward pressure by thespring 27 on the door so that after releasing the touching pressure, the door will readily open automatically.

With the door open, the components of themagnetic catch structure 13 are as illustrated in FIGURE 2 and to close the door, it is only necessary to place theplate 14 in contact with the front edges of theside plates 21 and 22 where they are held by magnetic attraction. The door will then not reopen until an intentional touching pressure is applied in the direction of the arrow P to again compress tbesprings 25 and 26.

From the foregoing description, it will thus be evident that the present invention has provided a greatly improved touch latch mechanism for cabinet doors. As in the case of the mechanical type touch latches presently available, there is not necessary any external knobs,

handles or the like to open or close the cabinet door so that a desired aesthetic appearance is realized. In addition, however, there is no possibility of a positive locking of the door in a closed position since there isv not involved mechanical moving parts subject to failure. It will be clear that there is essentially only one moving part, to wit thepermanent magnet structure 23 with associatedside plates 21 and 22 and guide clips l19 and 20. This structure moves as a unit into thechannel 24 defined lbetween the plates and 16. Should this movable structure be locked in its innermost position by some fault, the field at the forward ends of theside plates 21 and 22 is decreased sufficiently that thedoor 12 will not be held closed and thus the catch mechanism is clearly exposed for ready repair. On the other hand, should the movable structure become stuck outwardly or bind outwardly for some reason, the door can still be held closed by the magnetic means and to open the same it is only necessary to apply sufficient outward force to overcome the magneticattraction coupling poles 21 and 22 to plate 14. This force can normally be applied without damaging the door or necessitating removing the hinges.

While the invention has been described with respect to mounting the permanent magnet portion on the cabinet frame and the attracting plate to the door, it is of course understood that these parts could be reversed. Further, while the non-magnetic portions of the device have been described as plastic, any other non-magnetic material such as brass or ceramic could be used.

What is claimed is:

1. A magnetic touch latch comprising, in combination:

(a) a magnetic catch device adapted to be secured to a cabinet frame and including (1) a permanent magnet; (2) means for decreasing the magnetic field strength at one portion of said magnet; and (b) a plate member adapted to be secured to the inside surface of a door for said cabinet in a position to be magnetically attracted and held by said one portion of said magnet, said means for decreasing the magnet field strength of said one portion of said magnet comprising a member of high permeability normally spaced from another portion of said permanent magnet by a given distance, said given distance, being decreased by a touching pressure on said door urging said door against said magnet such that flux in said other portion of said magnet is shortcircuited through said member to thereby decrease the magnetic field strength at said one portion, permitting said door to be released to an open position.

2. A latch according to claim 1, including first spring means for holding said permanent magnet at said given distance from said member, said first spring means being compressed when said given distance is decreased; and Second spring means between said permanent magnet and plate member exerting a separating force therebetween less than the magnetic attractive force on said plate when said member is at said given distance and greater than the magnetic attracting force when said magnetic field strength is decreased by decreasing said given distance, whereby said second spring means releases said plate from said one portion of said permanent magnet after said given distance is decreased.

3. A magnetic touch latch for holding a cabinet door closed against a cabinet frame by magnetic attraction and responsive to a touching pressure on the door urging the door towards said frame to magnetically release the door so that the same opens, comprising, in combination:

(a) magnetic catch device adapted to be secured to said frame, said device including (1) a xed magnetic means;

(2) non-magnetic guide means fixed to said magnetic means and defining a guide channel normal to and opening towards the inner surface of said door when said door is closed;

(3) a movable magnet means received in the open end of said channel;

(4) rst spring means connected between said fix-ed magnetic means and said movable magnet means biasing said movable magnet means outward of said channel to a spaced position from said fixed magnetic means;

(5) second spring means extending from said movable magnet means towards said door; and

(b) a plate member adapted to be secured to the inside surface of said door in a position to compress said second spring means and be magnetically attracted to and held by said movable magnet means when in said spaced position, whereby application of a touching pressure to said door urges said movable magnet means into said channel to a position adjacent to said fixed magnetic means, said fixed magnetic means providing a new fiux path for said magnet means whereby the magnetic attraction of said plate to said movable magnet means is weakened sufficiently to be overcome by said second spring means so that said plate is separated from said movable magnet means and said door is free to open when said touching pressure is relieved, said first spring means then returning said movable magnet means to its said spaced position.

4. A latch according to claim 3, in which said fixed magnetic means comprises a magnetic member having a high permeability; a holder secured to the rear surface of said member, said guide means comprising plastic plates fixed to opposite siles of said holder and extending forwardly beyond a front surface of said member towards said door when closed to define therebetween said channel, the front portion of said member extending into said channel, said movable magnet means comprising a permanent magnet in the form of a block with side plates of magnetic material extending forwardly and rearwardly beyond the forward and rearward surfaces of said block to define front and rear poles; and non-magnetic clip means on said poles dimensions to be received in said channel and guide movement of said block and poles from said spaced position to an inner position in which the forward portion of said member is received between the rear poles thereby reducing the magnetic attraction of the front poles to said plate.

5. A latch according to claim 4, in which said first spring means comprise compression springs received between opposing bores in said clip means and holder, said second spring means extending from a front bore in one of said clip means with a free end positioned to be engaged and compressed by said plate.

References Cited UNITED STATES PATENTS 2,117,132 5/1938 Bagermann 292-2515 2,673,111 3/1954 Teetor 292-2515 2,854,273 9/1958 Cunningham 292-2515 2,888,290 5/ 1959 Pierce 292-2515 2,915,681 12/1959 Troy 317-123 RICHARD E. MOORE, Primary Examiner E. J. MCCARTHY, Assistant Examiner U.S. C1. X.R. 335-285

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