Releasable Magnetic Latch

Abstract

A magnetic latch especially suitable for cabinet doors and the like having spring means to be biased upon manual engagement and urging of the cabinet door inwardly from its normal closed position and to urge and door outwardly to an open position and past the range of the magnetic latching effect when the door is suddenly released from said manual engagement.

Description

This invention has to do with a magnetic latch and is more particularly concerned with a releasable magnetic door latch which is such that it will release upon the momentary application of pressure and slight movement of the door towards and beyond its normal closed position.

In the latch art, particularly in that portion of the art concerned with holding cabinet doors and the like closed, magnetic latches have become very popular. The ordinary magnetic door latch includes a housing fixed within the cabinet and carrying a permanent magnet and an armature in the nature of a ferrous metal plate which is fixed to the inside of the door and adapted to engage the magnet when the door is closed whereby the door is normally, magnetically, held closed. To release such latches or holding devices, a handle is provided on the exterior of the door for manual engagement so that the door can be manually urged open and the armature can be moved out of the field of the magnet.

In the door latch art there is another form of latch which is rapidly growing in popularity. This form of latch is such that a handle need not be provided on the door to effect releasing of the latch, but is such that the latch can be released and the door swings open upon the momentary application of pressure on, and limited movement of, the door inward and slightly beyond its normal closed position. This form of latch characteristically involves spring loaded toggle levers and the like and is a rather complicated and costly mechanism requiring close alignment for proper operation.

An object of this invention is to provide a new and improved latch which incorporates the advantages and desirable features of the two above-referred to forms or types of latches, that is, a magnetic latch which is releasable upon the momentary application of pressure and inward movement of the door.

It is a further object of my invention to provide a latch of the character referred to which is extremely simple, easy and economical to manufacture, highly effective and dependable in operation, and does not require close alignment.

The foregoing and other objects and features of my invention will be fully understood and will become apparent from the following detailed description of typical preferred forms and embodiments of my invention throughout which description reference is made to the accompanying drawings, in which:

FIG. 1 is an isometric view of a cabinet and related door, with said door in a normal closed position;

FIG. 2 is a view similar to FIG. 1, with the door in its open position and showing my invention related thereto;

FIG. 3 is an enlarged sectional view taken as indicated by line 3-3 on FIG. 1;

FIG. 4 is an enlarged detailed sectional view of a portion of the structure shown in FIG. 3;

FIG. 5 is a sectional view taken as indicated by line 5-5 on FIG. 3;

FIG. 6 is a view taken as indicated by line 6-6 on FIG. 3;

FIG. 7 is a view taken as indicated by line 7-7 on FIG. 3;

FIG. 8 is a view similar to FIG. 3 showing another form of my invention;

FIG. 9 is a view taken as indicated by line 9-9 on FIG. 8; and,

FIG. 10 is a view of a modified form of the instant invention.

Referring to the drawings, the latch L that I provide is shown related to a cabinet structure C, which structure is shown as having a flat, front, vertical cabinet surface 10 with a square or rectangular opening 11 therein to provide access to a compartment 12. The compartment 12 is shown as having a bottom wall or shelf 13, side walls 14, a back wall 15 and a central horizontal shelf 16.

The cabinet structure further includes a closure or door 17 with flat front and rear surfaces 18 and 19 substantially corresponding in configuration and dimensions with said opening and so that it freely occurs within and occupying the opening. The door is pivotally mounted at one vertical side thereof to an adjacent vertical side of the opening 11 by suitable hinge means 20.

The door is adapted to normally occur in a closed position, within the opening 11 and with the front surface 18 thereof flush with the surface 10 of the cabinet, as indicated by FIG. 1, and is adapted to swing or pivot to an open position, ad indicated in FIG. 2.

The shelf 16 in the cabinet has a front edge 21, which edge is spaced rearward or inward from the front 10 of the cabinet and within the compartment 12 so that when the door is in its normal, closed position, the edge 21 is spaced a short, predetermined distance inward or rearward of the rear surface 19 of the door 17.

The latch L includes a housing H arranged and fixed in the chamber 12 of the cabinet adjacent the side thereof remote from the hinge means 20 and an armature plate A arranged and fixed to the rear surface 19 of the door 17 adjacent the vertical side edge thereof remote from the hinge means 20 and hereinafter referred to as the outer edge or edge portion of the door. The armature is positioned so that it is in substantial horizontal and vertical alignment with the housing H when the door is in its normal closed position.

The armature A is a simple, flat, elongate plate of ferrous metal secured to the inner rear surface 19 of the door by a pair of screw fasteners 25, as clearly illustrated in the drawings.

The housing H is a simple, inexpensive structure molded of a suitable plastic or suitably formed of sheet metal.

The housing H includes a simple, rectangular boxlike body portion with front and rear walls 30 and 31, top and bottom walls 32 and 33, and end walls 34. In addition, the housing includes a pair of flat, laterally and oppositely outwardly projecting mounting tabs 35 at its opposite ends and in a common plane with the top wall 32. The tabs 35 are provided with slotted fastener-receiving slots 36 opening vertically and extending from front to rear.

The housing H is arranged adjacent the bottom surface 37 of the shelf with its top wall 32 and tabs 35 in flat bearing engagement therewith and is secured thereto by screw fasteners 38 engaged in and through the slots 36.

In practice, the top wall 32 can be eliminated, in which case the body opens upwardly and is closed by the portion of the shelf overlying it. Such a construction and relationship of parts is particularly adaptable when the housing is formed of sheet metal and greatly facilitates assembly of the latch, as will be apparent from a study of the drawings.

The walls 30 through 34 of the housing define a chamber X.

The front wall 30 which is disposed forwardly in the cabinet, is provided with a substantially rectangular opening 40 and its inside or rear surface defines a flat, rearwardly disposed stop shoulder 41 about the perimeter of the opening 40.

Arranged within the housing and the opening 40 in the front wall thereof is a rearwardly opening cuplike carrier C having a flat, forwardly disposed front wall 42, top and bottom walls 43 and 44, end walls 45, and an outwardly projecting flange 46 about the rear edges of the top, bottom and end walls and defining a forwardly disposed stop shoulder 47 about the perimeter of the carrier. The carrier corresponds generally in front configuration and dimension with the opening 40 and is slidably engaged in said opening with the front wall 42 spaced forward of the front wall 30 of the housing H and with the flange rearward of the front wall of the housing. The forwardly disposed stop shoulder 47 defined by the flange 46 on the carrier C opposes and is normally engaged and stopped on the rearwardly disposed stop shoulder 41 defined by the front wall 30 of the housing, about the opening 40 therein.

Arranged within the carrier cup C is a pair of permanent magnets M and M', the axis of the poles of which extend fore and aft and so that each has a front and a rear pole. The front pole of one of said magnets, for example, the magnet M, is its north pole and engages and stops on the rear surface of the front wall 42 of the carrier while the front pole of the other magnet M' is its south pole and engages the front wall of the carrier in the same manner as the magnet M.

In accordance with the above, the south pole of the magnet M and the north pole of magnet M' are the rear poles of said magnets.

In practice and as illustrated, the axial extent of the magnets correspond with the depth of the carrier and so that the rear poles thereof occur in substantially the same plane as the flange 46 of the carrier.

In addition to the above and in combination with the magnets M and M', I provide a flat coupler plate 50 established of ferrous metal and engaged with and extending between the rear poles of the magnets to conduct magnet flux between said rear poles.

The plate 50, in addition to magnetically coupling the magnets, serves the added function of being a retainer or keeper and retains the magnets within the carrier. The plate 50 is greater in lateral and vertical extent than the interior of the carrier and is arranged adjacent the rear side or end of the carrier with its perimeter or edge portion in bearing and stopped engagement with the rear surface of the carrier flange 46.

The plate 50 is retained and held in fixed relationship with the carrier by means of two or more tabs T on and about the perimeter of the flange 46, which tabs are bent rearwardly and thence inwardly, over and about the perimeter of the plate 50 to hold the maintain the plate captive and in desired position.

The magnets M and M' are preferably arranged in lateral spaced relationship within the carrier and, in practice, if desired, can be fixed to the front wall 42 of the carrier and/or to the plate 50 by means of a suitable cement.

With the structure set forth above, it will be apparent that when the latch is in use and the front wall 42 of the carrier C engages the armature A, the armature, like the plate 50 occurs within the field of the magnets M and M' to conduct flux between the forward or front poles of the magnets and the armature is magnetically sealed with the front wall 42 and is yieldingly held in said magnetic field.

The front wall 42 of the carrier C, occurring between the armature A and the forward poles of the magnets and being established of nonferrous material establishes an air gap of set and predetermined extent between the magnets and the armature, which air gap is suitable compensated for by the strength of the magnets.

Arranged within the chamber X and between the plate 50 and the rear wall 31 of the housing H, is a pair of compression springs S, which springs normally yieldingly urge the carrier forwardly to its normal forward, stopped position.

If necessary or desired, the rear wall 31 of the housing can be provided with forwardly projecting spring guides 51 to maintain the springs in proper position in the housing.

The latch structure described above is positioned on the shelf so that when it is in its normal position, the front surface of the carrier engages the rear surface of the armature plate A when the door 17 is in its closed position, that is, when the front surface 18 of the door in a common plane with the front 10 of the cabinet.

When the armature A and carrier C are engaged in the manner set forth above, the armature is within the flux field of the magnets within the carrier and the door is held in its normal closed position.

When it is desired to open the door, the door is manually urged rearwardly and inwardly beyond its normal closed position and to a position where it stops against the front edge 21 of the shelf 16, or, in some circumstances, against the front wall 30 of the housing H.

When the door is urged and moved inwardly in the manner set forth above, the carrier is moved inwardly and rearwardly in the housing, against the resistance of the springs S, further compressing said springs.

Upon sudden release of that pressure urging the door inwardly, the springs urge the carrier and the door forwardly. Forward movement of the carrier is stopped suddenly and positively by the stop shoulders 41 and 47 when the carrier reaches its normal position and the door 17, due to the mass inertia imparted into it or the momentum generated therein by the springs S, continues to move forwardly and out of the flux field of the magnets, to its open position.

It is to be noted that the generating or development of that high or great force which is required to break the magnetic seal between the contacting armature and magnet or magnet assembly is generated by that impactlike force, which approaches infinity, when the magnet is abruptly stopped by the stop shoulders. In this regard, since force equals mass times acceleration, acceleration approaches infinity when the mass is suddenly and abruptly stopped and the force generated by such stopping likewise approaches infinity.

In practice if the latch does not release, when moved forwardly by the spring, the relation between releasing force and holding force can be increased by: (1) increasing the minimum air gap to decrease the holding force; (2) using stronger springs or allowing longer spring travel; and/or (3) using a weaker magnet or magnets.

Increasing the air gap between the magnets and armature to vary and adjust the holding effect of the latch can be easily and effectively accomplished by means of a strip 60 of pressure adhesive insulating tape applied to the front wall of the carrier and/or to the armature plate, as indicated in the dotted lines in FIG. 4.

In accordance with the foregoing, it will be apparent that with the latch that I provide, the spring loaded magnetic carrier normally maintains the door closed and that upon pushing the door inwardly slightly and then releasing it, the spring means which loads the carrier and normally holds it in its normal position urges the door forwardly and out of latched or held relationship with the carrier.

It is to be understood and will be apparent that the housing H need not be mounted on the bottom of a shelf as illustrated and described, but can be mounted in any manner in the cabinet which permits proper orientation of the carrier and necessary and proper relationship of the carrier with the armature A.

In FIG. 8 of the drawings, I have shown another form of my invention wherein a single permanent magnet M.sup.2 is provided.

The details of construction of the housing H' and carrier C' in this second form of the invention can be similar to like elements and parts in the first form of the invention and vary therefrom in dimensions only.

In this second form of the invention and since a single permanent magnet is provided, a ferrous cup or C-core K having a base or bottom 60 and a forwardly projecting annular side 61 is arranged in the carrier C' and about the magnet with its base 60 engaging the rear end or pole of the magnet and the forward rim of the legs engaged and stopped on the rear surface of the front wall 42 of the carrier. The magnet M.sup.2 can be cemented or otherwise fixed to the core K as desired.

The magnet and core assembly can be retained in the carrier by a plate such as the plate 50 in the first form of the invention, or can, if desired and as illustrated, be retained in the cup by bent over tabs T' on the flange 46 of the carrier. The tabs T' are similar to the tabs T in the first form of the invention, but are of greater longitudinal extent.

The core K in this second form of the invention serves to carry the flux from the rear pole of the magnet around to the armature A', which flux flows through the armature back to the forward pole of the magnet, when the door 17' is closed.

In practice, the housing and the means provided to mount the housing can be of any desired and suitable form. For example, and as illustrated in FIG. 10 of the drawings, the housing H.sup.2 is a cylindrical part with apertured mounting flanges at one end and such that it can be slidably engaged and securely fixed in a cylindrical hole bored or otherwise established in one of two relatively movable parts which it is desired to releasably latch together.

It is to be understood that whether the housing is fixed to a fixed or immovable part, such a a cabinet shelf, or to a movable part, such as a cabinet door, and the armature is fixed to the immovable part or the movable part, is a matter of desirability of installation and/or choice.

A drawer or sliding door latch release mechanism established in accordance with the spirit of this invention can be provided to hold a drawer or sliding door in exact closed position and allow opening of said drawer or sliding door without use of unsightly hardware or "pulls." In such embodiments of my invention, best design and proportioning would likely dictate the use of stronger springs and/or weaker magnets than are employed for swinging door latches, such as referred to above.

It will be apparent that the latch means that I provide is extremely simple and practical to manufacture and install and highly effective and dependable in operation.

Having described only typical preferred forms and applications of my invention, I do not wish to be limited or restricted to the specific details herein set forth, but wish to reserve to myself any modifications and/or variations which may appear to those skilled in the art.

Claims

IN THE CLAIMS:

1. In combination, a structure with two relatively shiftable parts, one part being shiftable relative to the other part from a normal position rearwardly to a spring-loading position and forwardly to an open position, a ferrous armature on one part, permanent magnet means shiftably carried by the other part, power spring means normally yieldingly urging the magnet means forwardly toward said other part, stop means limiting forward movement of the magnet means relative to said other part and to a normal stopped position where said armature is engaged and sealed with said magnet means when said one part is in its normal position, said magnet means being moved rearwardly relative to said stop means and said power spring means being biased upon manual rearward movement of said one part from its normal position to said spring-loading position and operable to urge said one part and the armature forwardly to its open position where the armature is disengaged with the magnet means.

2. A structure as set forth in claim 1 wherein said magnet means is carried by a housing fixed to said other part and said stop means includes a rearwardly disposed stop shoulder in the housing and a forwardly disposed stop shoulder on said magnet means opposing and normally engaging the rearwardly disposed stop shoulder.

3. A structure as set forth in claim 2 wherein said spring means includes a compression spring within the housing between the magnet means and a rear wall of the housing.

4. A structure as set forth in claim 2 wherein the magnet means includes a rearwardly opening nonmagnetic cup with a flat, forwardly disposed armature engaging wall, rearwardly projecting sidewalls and an outwardly projecting flange on said sidewalls defining said forwardly disposed stop shoulder, a forwardly opening pole piece with a base portion and forwardly projecting sides within the cup and stopped against the front wall and a permanent magnet between said sides and engaging said base portion.

5. A structure as set forth in claim 4 wherein said housing has a front wall with an opening in which the cup is slidably engaged and defining said rearwardly disposed stop shoulder.

6. A structure as set forth in claim 4 wherein said spring means includes a compression spring within the housing between the magnet means and a rear wall of the housing.

7. A structure as set forth in claim 6 wherein said housing has a front wall with an opening in which the cup is slidably engaged and defining said rearwardly disposed stop shoulder.

8. A structure as set forth in claim 1 wherein said permanent magnet means is carried by a housing, said housing having slotted mounting tabs projecting therefrom and fixed to said other part by fasteners engaged through the tabs and into the cabinet, said housing having front and rear walls, said front wall having an opening to receive the magnet means and defining a rearwardly disposed stop shoulder of said stop means, said permanent magnet means including a rearwardly opening, nonmagnetic cup slidably engaged in said opening in said front wall and having a front wall and an outwardly projecting flange rearward of said front wall and defining a forwardly disposed stop shoulder of said stop means normally engaging said rearwardly disposed stop shoulder, a ferrous metal pole plate in the cup and a pair of permanent magnets within the cup and engaged between the plate and the front wall of the cup, the poles of the magnets being forwardly and rearwardly disposed, the poles of the two magnets being oppositely disposed, said spring means including a compression spring between the cup and the rear wall.

9. A structure as set forth in claim 8 wherein said cup normally projects forwardly from said housing and engages the armature plate on said one part and holds that part in its normal closed position, said one part being adapted to be manually urged rearwardly toward the other part and released whereupon the spring means urges the magnet means and said one part forwardly to where the magnet means is stopped by said stop means and said one part moves forwardly, moving said armature plate from within the magnetic field of said magnet means.

10. In combination, two parts shiftable in one direction relative to each other from a normal closed position to a spring-loading position and in the opposite direction relative to each other to an open position, a push-to-release magnetic latch related to said parts to releasably hold said parts in said normal position and including a permanent magnet means carried by one part and an armature means carried by the other part, said magnet means establishing a magnetic seal with the armature means when the parts are in their normal and spring-loading positions, one of said means being a fixed means in fixed position on the part which carries it, the other of said means being a movable means shiftably carried in a housing fixed to the part which carries it, power spring means carried by the housing and normally yieldingly urging the movable means toward said fixed means, stop means in and between the movable means and the housing to limit movement of the movable means toward the fixed means and to stop the movable means in a normal stopped position when the parts are in their normal and open positions, said movable means being movable from its normal stopped position to an actuated position upon movement of one part relative to the other part in said one direction and to said spring-loading position, said power spring means being biased loaded upon movement of the movable part to said actuated position, said power spring means when biased loaded urges the movable means to its normal stopped position and the parts in said opposite direction relative to each other from their spring-loading position to their normal position and thence to their open position whereby the magnetic seal between the fixed and movable means is broken and the armature means is moved from within the magnetic field of the magnet means.