US2942907A - Magnetic latching mechanism - Google Patents

Description

June 1960 G. w. NAGEL ETA]. 2,942,907

mnmc LATCHING nmcwmxsu 3 Sheets-Sheet 1 Filed larch 25. 195'] FlG. I.

FIGS.

INVENTORS GEORGE W. NAGEL, a

CLYDE A.BOOKER,JR.

ATTORNEY June 28, 1960 s. w. NAGEL ETAL 2,942,907

MAGNETIC LATCHING MECHANISM Filed March 25, 1957 3 Sheets-Sheet 2 NOE INVENTORS GEORGE w. NAGEL,& CLYDE A.BOOKER,JR. BY W? ATTORN lilrrrz 1111,,

June 28, 1960 G. w. NAGEL EI'AL 2,942,907

mcmxc LATCHING nmcmmxsu 3 Sheets-Sheet 3 Filedlarch 25, 1957 623-0002: IOP J QEQGJO K000 8.25 23 5:58 65:93 noon INVENTORS GEORGE W. NAGELfi LBOOKER JR.

ATIORNEY E CLYDE United States Patent MAGNETIC LATCHING MECHANISM George w. Nagel and Clyde A. Booker, in, Pittsburgh, Pa., a'sig'nors to, Westinghouse Electric corporation, East Pittsburgh, Pin, a corporation of Pennsylvania Filed Mar. 25, 1957, Ser. No. 648,153 a (611292 4515 This invention relates to latching mechanisms for cabinet doors and more particularly to a permanent magnet latch structure suitable for use with heavy gasketed doors such as refrigerator cabinet doors. I

One of the principal requirements of a latch mechanism for a gasketed closure such as a refrigerator door is that the mechanism provide a pull-up force to the door when closed to insure compression and complete seating of the door gasket. In the case of the domestic refrigerator, the mechanical latch mechanisms currently in use apply a continuous force to the closed door of the order of 35 pounds. Latch mechanisms for this service are also required to provide a force during the final range of door closing movement to effect initial compression of the gasket. Otherwise, the user finds it necessary to slam the door to compress the gasket. In all, such a latch mechanism may be called upon to supply a force of the order of'90 pounds while moving the-door through its final one-quarter inch of movement, and to apply a uniform holding force to the door when it is closed.

Mechanical latch mechanisms have been designed to satisfy the above-mentioned requirements. However, such mechanisms are generally complicated and expensive to manufacture. On the other hand, magnetic latches have been proposed which are comparatively inexpensive. In general, however, the prior magnetic latches have not been capable of providing the necessary closing and holding forces for use with gasketed doors.

Accordingly, it is an object of this invention to provide an improved magnetic latch capable of etfectively latching a gasketed door.

The permanent magnet latch structure contemplated by this invention may be briefly described as follows: The latch consists of two principal components namely, a magnet assembly and an armature assembly. One of these components is adapted to be mounted on the cabinet of a refrigerator or similar structure while the other is adapted to be carried by the door. In the preferred embodiment which will subsequently be described in detail, the magnet assembly is mounted on the cabinet and the armature assembly is mounted on the door in such a manner as to be engageable with the magnet assembly when the door is moved to its closed position. The armature assembly includes a spring for biasing the armature inwardly of the door and which, in effect, biasesthe door against the cabinet when the armature assembly is in contact with the magnet assembly and held thereagainst by magnetic force. The latch of this invention also incorporates means for moving the armature assembly relative to the door in which it is mounted to permit the door to be moved a short distance away from the cabinet to break the seal between the door and cabinet while the armature assembly is still held by the magnet assembly. Once moved to its projecting position relative to the door, the armatureassembly is locked against the bias of the spring and a releasing member comes into play to separate the armature assembly from the magnet assembly and permit the door to be opened. Provision is also made for releasing the armature assembly locking means when the armature assembly contacts the magnet assembly as the door is moved toward closed position. Releasing the armature assembly permits the spring to retract the armature assembly into the door and pull the door up against the cabinet compressing the gasket into sealing engagement with the cabinet.

It is another object of this invention to provide an improved permanent magnet assembly for magnetic latches, which assembly will retain its magnetic properties for a long period of time.

It is a further object of this inventionto provide an improved permanent magnet assembly with a sufficiently restricted magnetic field so as not to damage Watch mechanisms which come in close proximity thereto.

These and other objects are effected by the invention as will 'be apparent from the following description taken in connection with the accompanying drawings, forming a part of this application, in which: I

Fig. 1 is a phantom perspective view of a portion of a refrigerator cabinet showing the magnetic latch assembly of this invention;

Fig. 2 is a horizontal sectional view of the latch mechanism taken as indicated by the line I-III of Fig. 1;

Figs. 3, 4 and 5 are hor zontal sectional views of the latch mechanism showing the mechanism in various stages of its sequence of operation;

ig'. 6 is a vertical sectional view of the latch mechanism taken along the line VI-VI of Fig. 2;

Fig 7 is a vertical sectional view of the latch mechanism taken along the line VII Vl-I of Fig. 2; and

Fig. 8 is a vertical sectional view of the latch mechanism taken along the line VlHVlH of Fig. 2.

Referring to the drawings, the numeral '11 designates a refrigerator cabinet having adoor 12 hingedly mounted on the front thereof. The wads of the cabinet 11 are defined by anouter shell 13 and an inner liner 14 mounted within and spaced from the outer shell. The space between theouter shell 13 and the inner liner 14 is filled with heat insulation (not shown) and the front of the wall space is closed by athermal insulating breakerstrip 16 extending between the front edges of theshell 13 and liner 14. Thedoor 12 consists of anouter panel 17 and an inner panel 18 with heat insulation (not shown) disposed therebetween. Suitable means, such as screws (not shown), are provided for attaching the edge of the inner door panel 18 to theflanged edge 19 of the outer door panel, and for securing aresilient gasket 21 to the inner face of the door. When thedoor 12 is closed, thegasket 21 engages, and is compressed against, an inwardly turnedflange 22 on thecabinet shell 13 as shown in Fig. 2.

Thedoor 12 is held closed and is biased against the cabinet 11 by means of the magnetic latch structure of this invention. This latch is designated generally by thenumeral 23 and consists of two principal elements or sub'assemblies, namely, themagnet assembly 24 and thearmature assembly 26. In the preferred embodiment of the invention illustrated in the drawings, themagnet assembly 24 is mounted on the cabinet 11 and thearmature assembly 26 is mounted on thedoor 12, though the position of these two assemblies can be reversed. It will be noted that themagnet assembly 24 and thearmature assembly 26 are mounted in such a manner that they are in axial alignment with one another and have their face areas in abutment when the door 1-2 is in its closed position.

The magnetic latch 2-3 is actuated to open the door 12 V by manually operable means carried by thedoor 12 and capable of applying an actuating force to thelatch armature assembly 26, Thisnianually operable means includes ahandle 27 pivotally mounted at 28 to a supportj which are spaced apart by thepole separator 42.

should be pointed out that the magnet assembly is capable attached at 33 to an inner supportingplate 34 carried f on the inner surface ofouter door panel 17. The opposite or free end oflever 32 is arranged to engage one end ofthelatch armature assembly 26. It can readily be seen that movement of thehandle 27 in a counterclockwise direction (as viewed in Fig. 2) movespin 31 inwardly of the door, causing a clockwise movement of lever 32' aboutpivot 33. The free end oflever 32 then engageslatch armature assembly 26 and applies a force thereto for the actuation of the latch, as will be described later. Lever 32 and, consequently,handle 27 are biased to their inactive positions, as illustratedin Fig. 2, .bya-spring 36 at'thepivotal connection 33 forlever 32.

The construction of thelatch magnet assembly 24 and its mounting arrangement are best shown in Fig. 2. The :magnet assembly 24 comprises a cylindrical shaped permanent magnet 37 encased in pole structure which includes a hollow cylindricalouter pole member 38 having v a tapered opening '39 in the face thereof adapted to. re-

ce'ive a tapered plug-like inner pole member 41 which is magnetically insulated from theouter pole member 38 by a frusto-conical separator 42 of non-magnetic material, such as brass. The other end of theouter pole member 38 is closed by aplug 43 having a boss 44 thereon by means of which themagnet assembly 24 is mounted on the cabinet 11. Theouter pole member 38, the inner pole member 41 and theend plug 43 form a magnetic flux circuit for the magnet 37 and are, therefore, preferably constructed of metallic material having high magmetidpermeability. Themagnet assembly 24 is preferably resiliently mounted to the cabinet 11, as bymeans -of arubber grommet 46 surrounding the boss 44, and

is carried by an insulating plate 47 extendingbetween'the cabinet shell 13 and the liner 14.

. Themagnet assembly 24 projects through an opening provided therefor intherbreaker strip 16 and presents at its outer face two concentrically arranged magnetic poles It of exerting a magnetic field sufficiently strong to maintain a refrigerator door in its closed and sealing position,

and yet, is so constructed as to provide a low reluctance Z path for the magnetic flux from magnet 37 which prevents the magnet from becoming demagnetized when themagnetassembly 24 is open-circuitedbyrthe door 12 being opened. In this regard, thepole separator 42 is made of very thin material, of the order of inch thick, and

provides a low reluctance air gap between themagnet pole pieces 38 and 41. Thus, even when themagnet assembly 24 is open-circuited, sufficient magnetic flux flows through thepole members 38 and 41 to prevent the magnet fi'om becoming demagnetized.

Themagnet assembly 24 of this invention produces a strong, though concentrated and highly confined, magneticfield which reduces the likelihood of damage to 7 watches or other delicate instruments worn or carried by persons actuating the latch; Some prior permanent magnetic latches produced a large stray magnetic field which could easily he accidentally entered by the hand of a person opening the door with which the latch is associated and presented a considerable hazard so far as damage to watches is concerned. As is well understood, the amount of stray magnetic field about a permanent magnet structure is proportional to the open circuit air gap. in the -magnetic circuit. The extremely small air gap, i.e., the

space between the inner pole 41 and theouter pole 38 of the magnet assembly of this invention, insures a con- V centration of the magnetic. flux between the two poles with little stray field. Furthermore, the fact that theouter pole 38 of thisimproved magnet assembly 24 completelysurrounds, in concentric fashion, the inner pole outer surface of the outer door 41, the possibility of stray flux paths existing in the area surrounding thecmagnet structure is further reduced.

The tapered interfitting portions of theouter pole member 38 and the inner pole member 41 simplify the manufacture of themagnet assembly 24. Both the tapered outer surface of the inner pole 41 and the inner surface of theouter polemember 38 defining the opening 39 may be easily manufactured to close tolerances by simple turningoperations. Any variations in the dimensions of these parts is automatically compensated for during assembly by the relative axial shifting of the parts as they are forced together with thepole separator 42 therebetween. Accurate spacing between the two pole members is theneasily maintained by careful selection of the thickness of the material employed for theseparator 42. Any axial misalignment between the inner. pole member 41 and theouter pole member 38 can be corrected by grinding the face of themagnet assembly 24 to provide -.a smooth flat surface thereon.

Themagnet assembly 24 attracts thereto a'portion 48 V of the armature-assembly 26 which willbe termed the armature. Thearmature assembly 26 is carried by arod member 49 having one end loosely coupled to the doorouter shell 17 by a pin connection'Sl. Therod member 49 extends along the axis 10f the generally cylindrical armature assembly 26-and has adiametric hole 52 drilled therethrough near its unsupported end. Thishole 52 in therod 49 loosely receives anelongated pin 53 which passesthrough and is closely confined by diametrically spaced openings in one end of a locking sleeve 54 '-sl-idably positioned over therod member 49. The clear- 1 ance betweenpin 53 and therod hole 52 permits limited axial movement of the lockingsleeve 54 onthe rod 49'. The outer extensions ofpin 53 abut one face of awasher 56 loosely positioned around clockingsleeve 54 and which serves as an abutment for one end of acompression spring 57 surrounding, in concentric fashion, the lockingsleeve 54." The other end of thespring 57 abuts against ofrod 49; actual contact between thearmature 48 and therod 49 being prevented by a shock-absorbingpad 50.

The pad may be constructed of rubber, leather or "other material having cushioning qualities.

Thespring 57, in biasing thearmature 48 inwardly of the'door, actually biases thedoor 12 against the cabinet 11 when the door is-in closed position. This action can be readily comprehended if thearmature 48 is considered as being stationary,,as it would be if thedoor 12 were closed and thearmature 48 held tightly against themagnet assembly 24. In this condition, thearmature sleeve 59 and itsend wall 58, being rigidly attached to thearmature 48, would also be stationary. Thespring 57,

I 62 adapted to be engaged by the actuatinglever 32 carried by the cabinet outer shell and forming a part of the actuating means for the latch. 'Sleeve member 63. functions as a releasing, or separating, member. for the latch mechanism, as will be hereinafter described. It will -be notcd that thelever 32 engages thisend wall 62 of theouter sleeve 61 insuch a manner as to transmit thereto movement which is axial with respectto therod member 49 which, supports the armature assembly.

Forces which are applied to thisend wall 62 of theouter sleeve 61 are transmitted to thearmature sleeve 59 by a smallmetal locking ball 63 carried in the annular space between the lockingsleeve 54 and theouter sleeve 61. This lockingball 63 bears against theend wall 58 of thearmature sleeve 59 and is prevented from moving circumferentially about the lockingsleeve 54 by anannular boss 64 extending from the face of theend wall 58 which is cut away at 65 to receive the ball 63 (see Fig. 8).

Relative rotative movement between the lockingsleeve 54 and thearmature sleeve 59 is prevented by an interlocking action between end extensions of thepin 53 and close fittinglongitudinal slots 66 in the armature sleeve 59 (see Fig. 6). This interengagernent between thepin 53 and theslots 66 does not restrict the relative longitudinal movement-of thearmature sleeve 59 with respect to the lockingsleeve 54, but merely prevents these members from rotating with respect to one another. It can thus be seen that the path of movement for the lockingball 63 along the surface of the lockingsleeve 54 is a longitudinally extending straight line.

The lockingsleeve 54 has anopening 67 therein, the centerline of which lies in the path of movement of the lockingball 63. Therod member 49 is also provided with acircumferential recess 68 in the vicinity of thissleeve opening 67. The side walls of therecess 68 slope gently inwardly toward the bottom of the recess, providing cam-like surfaces in the recessed area. Thesleeve opening 67 androd recess 68 cooperate to form a detent into which the lockingball 63 enters when the armature assemblyouter sleeve 61 is moved axially of therod 49. The sloping inner surface of thesleeve wall 62 cams theball 63 toward the centerline of therod member 49 and assists theball 63 in entering theopening 67 in lockingsleeve 54 and therod recess 68.

Operation Assume thedoor 12 of the refrigerator is closed. The elements of the magnetic latch are in a static condition in the positions shown in Fig. 2 of the drawings. The operator grasps thehandle 27, rotating it counterclockwise, and this motion is transmitted by means of thepin 31 to thelatch actuating lever 32 which undergoes clockwise rotation about thepivot 33. The free or left-hand end of the actuatinglever 32 engages the door mountedarmature assembly 26 of the latch through theend wall 62 of theouter sleeve member 61, moving the outer sleeve to the position shown in Fig. 3.

This movement of theouter sleeve 61 is transmitted by means of the lockingball 63 to the armaturesleeve end wall 58, compressing thespring 57 and moving thearmature sleeve 59 and thearmature 48 attached thereto. In other words, during this initial movement of the actuatinglever 32, theouter sleeve 61 and thearmature sleeve 59 move together as if mechanically interlocked, and .continue to do so until the mechanism reaches the position illustrated in Fig. 3, wherein the lockingball 63 has moved up to and is about to enter theopening 67 in the lockingsleeve 54.

This initial movement of thearmature 48 relative to thedoor 12 and against the bias of thespring 57 moves thedoor 12 relatively away from the cabinet 11, decompressing thegasket 21 and breaking the seal between the gasket and thecabinet flange 22. Thearmature 43 is retained against themagnet assembly 24 by the magnetic attractive force between these two members, which force is greater than the forces applied to thedoor 12 by the user of the refrigerator in moving thehandle 27.

This first range-of movement of the elements of thearmature assembly 26 is intended to break the seal of thedoor 12 with the cabinet 11. When a well sealed noted that during this seal-breaking operation, thearmature 48 of the latch remains in contact with themagnet assembly 24 and that no attempt is made to separate thearmature 48 from themagnet assembly 24 until the cabinet seal has been broken. The forces required to break the cabinet seal are, therefore, not superimposed on the forces which must be applied to break the magnetic attraction between thearmature 48 and themagnet assembly 24. The magnetic attraction between these latter two elements is overcome by forces associated with a second range of movement of the elements of thearmature assembly 26.

Continued movement of the actuatinglever 32 moves the elements 'of thearmature assembly 26 from the position shown in Fig. 3 to that illustrated in Fig. 4. During this additional movement the followin'g actions take place: The lockingball 63 is moved up to 'a position where it can pass through the locking sleeve opening .67 into therod recess 68. This movement of the lockingball 63 is assisted by the cam-like inner surface of the outersleeve end wall 62. Positioning of lockingball 63 withinrecess 68 locks together the lockingsleeve 54 and thearmature sleeve 59 as the lockingball 63 becomes wedged between the armaturesleeve end wall 58 and the edge of the lockingsleeve opening 67; a static, locked condition here exists by virtue of the armaturesleeve end wall 58 and the lockingsleeve 54 respectively engaging diametrically disposed points on the surface of the lockingball 63. This also locks thespring 57 in a compressed or cocked position.

Movement of the lockingball 63 into the recess 6 inrod 49 also permits slight relative movement of theouter sleeve 61 with respect to thearmature 48 and itssleeve 59. This relative movement betweenouter sleeve 61 and thearmature sleeve 59 is permitted by the shifting of the point of contact between the locking M1163 and the sloping surface of the outersleeve end wall 62; which action permits theend wall 62 to move closer to the armaturesleeve end wall 58. This movement is readily apparent if the relative positions of the face of the armature '48 and the open end of thesleeve 61 are compared between Figs. 3 and 4 in the drawing. This movement of the open end of theouter sleeve 61 beyond the plane of the outer surface of thearmature 48 forces themagnet assembly 24 and thearmature 48 apart a small distance. The amount by which thearmature 48 and themagnet assembly 24 are separated, though small, is suflicient to lower the attractive force between these members to a value which can be easily overcome by the operator of the latch in continuing to pull on the door 12' by means of thehandle 27. Release of thearmature 48 from themagnet assembly 24 permits the door to be opened and thearmature assembly 26 remains in the cocked position shown in Fig. 4 so long as the door remains open. When thedoor handle 27 is released, the handle and thelatch actuating lever 32 are returned to the position shown in Fig. 2 by thespring 36.

Fig. 5 illustrates the tripping action of thearmature assembly 26 as thedoor 12 is swinging to its closed position. Initial contact between thearmature assembly 26 and themagnet assembly 24 drives theouter sleeve 61 of the armature assembly back until its open end is flush with the face of thearmature 48. Theouter sleeve 61 slides freely through this movement since the actuatinglever 32 has been returned to its rest position beyond the path of movement of thesleeve 61. It will be noted the elements are so arranged that thearmature 48 contacts themagnet assembly 24 to initiate the tripping action of thearmature assembly 26 just prior to, or near, the point in the door swing where thegasket 21 contacts thecabinet flange 22 Engagement of thearmature 48 with themagnet assembly 24 obviously stops movement of thearmature 48 and the other elements of the armature assembly which are attached to or interlocked therewith. These elements which are locked to thearmature 48are'the armature sleeve 59, its end wall 58' and, through theball 63, the lockingsleeve 54,pin 53,washer 56 and, of course,

spring 57 which is compressed between thearmature sleeve'end wall 58 andwasher 56. Theinertia of the closingdoor 12, however, tends to carry the'door andarmature assembly rod 49 on toward the cabinet. The

rod 49 is free to move a short distance relative to the lockingsleeve 54 by virtue of the loose fit betweenhole 52 and thepin 53. As therod 49 is driven inwardly of thearmature assembly 26, the cam-shaped side wall of therodrecess 68. kicks the. locking ball 63'loose from 'its wedged position between the locking sleeve 55- and the armaturesleeve end wall 58. The armatur e sleeve '59eis, therefore, unlocked trom, the lockingsleeve 54 and spring 7' is free to expand andretract'the armature 48 within the door. Since thearmature 48 is held stationary by themagnet assembly 24, the expansion'force ofspring 57 is transmitted throughwasher 56 andpin 53 torod 49 and, consequently, to thedoor 12, causing the door to rnove toward the cabinet 11, compressing and seating the gasket 21.1The elements of the latch thereby return to the positions shown in Fig.2. 7 I

The extent of the closing movement of thearmature 48 with respect torod 49 is limited byithe engagement 'of the end of rod '49 with thecushioning pad 50 carried onthe inner face of the armature 48 (see Fig. 2). Pad

' 50c absorbs any shock occasionedby'the armature 48 being driven against the end ofrod 49 in the event the ,armature assembly 26 isvtrippedaccidentally whil'ethedoor 12 is" open. Furthermore, in constructing the latch of this invention, the elements are so designed that the movement'of thearmature 48 andpad 50 from the position. shown in Fig.5 to the po'sition shown in Fig. 2 is Yisuflicient' to compress but not crush thegasket 21, and

engagement of thepad 50 with the end of the rod '49 constitutes a stop for limiting compression of the gasket -21. r V a 7 From the foregoing it will be apparent that this invenmember operable in one position to engage portions of said one element and said separating member for causing said separating member to move with said one element as said one element ismoved to its cocked position, and means for moving said locking member to another position to permit movement of said separating member relative to said one element when said one element is moved to its cocked position, said manually operable means being adapted ,for moving said separating member relative to said one element and toward said other element when said one element is in its cocked position to separate said one element from said other-element.

2. In a magnetic latch structure including a magnet element and an armature element, one of said elements being carriedby acabinet structure'and the otherelement being carried by a door structure forsaid cabinet the invention. One such modification would be the reversal of the positions of themagnet assembly 24 and thearmature 48. Obviously, thearmature 48 could be secured to the cabinet 11 and a magnet assembly, similar ment and an armature element, one of said elements being carried. by a cabinet structure and the other element being carried by a door structure for said cabinet structure, means mounting one of said elements on one of said structures'for reciprocating movement normalto the plane of the door structure, a spring arrangedto urge said one element to a retracted position within the structure to which it is mounted, manually operable means for moving said one elementto a cooked position away from the structure to which it is mounted and toward the other structure, a separating member carried by the struc ture to which said'one element is mounted, a locking structure, means mounting oneof said elements' on one of said structuresforreciprocating movement normal to the plane ofthe door structure between an extended position and a'retracted position, a spring arranged to urge said one element toward the structure on which it is carried, a releasing member'carried bythe structure on which said one element is carried, manually'operable means for moving said releasing member away from the structure on which it is carried, a locking member operative in one position to engage portions of said one element and said releasing member to lock said one element to said releasing member, for movement therewith,

said locking member beingmovable to a second position engaging portions of said one element and the structure 'on which said one element is carried tolock said one member. from its said one position to its said second position when said one element is moved to its said extended position, said locking member in its second position' unlocking said releasing member to permit movement thereof relative to said one element and toward said other element whereby said releasing member separates said one element from said other element.

3. In a latch mechanism for a cabinet door, the combination of a magnet carried by'the cabinet in a position to engage an armature carried by the door, a releasing member carried by the door, means for supporting said armature and said releasing member for reciprocating movement normal to the plane of the door, a spring carried by the door and arranged to urgesaid armature to a retracted position within said door, manually operable means for moving said releasing member away from said door, a locking member operative in one position to engage portions of said armature and said releasing member to lock said armature to said releasing member for movement therewith, said locking member being movable to a second position to engage a portion of said armature and a member which is fixed relative said door to I lock said armature against movement relative to said door,

and means for moving said locking member fiom its first position to its second position when said armature has been moved to a cocked position away from said door, said locking member in its second position unlocking said releasing member to permit movement thereof relative said armature and toward said magnet whereby said releasing member separates said armature from said magnet.

References Cited in the file of this patent;

UNITED STATES PATENTS j V Byrd "Aug. 22, 1950 2,519,435 7 7 2,694,592 Borchers et a1. Nov. 1 6, 1954 2,808,281 Poe Oct. 1, 1957 2,813,741

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