US2926945A - Door latches and the like - Google Patents

Description

March 1, 1960 w. J. CLARK 2,926,945

DOOR LATCHES AND THE LIKE Filed Oct. 30, 1956 4 Sheets-Sheet 1 INVENTOR. MUM/V I (AH/FA March 1, 1960 w. J. CLARK DOOR LATCHES AND THE LIKE 4 Sheets-Sheet 2 Filed Oct. 30, 1956 March 1, 1960 w. J. CLARK 2,926,945

DOOR LATCHES AND THE LIKE Filed Oct. so, 1956 4 Sheets-Sheet 3 Nb Z64 1 74.51 F/q'6 I: AIME;

.95 INVENTOR. P74. 92 I mum/v1 cum/r March v1, 1960 w. J. CLARK 2,926,945

DOOR LATCHES AND THE LIKE Filed Oct. 30, 1956 4 Sheets-Sheet 4 INVENTOR. 4/! MM J 6! AAK United States Patent DOOR LATCHES AND THE LIKE William J. Clark, Philadelphia, Pa., assignor to Philco Corporation, Philadelphia, Pa., a corporation of Pennsylvania ApplicationOctober 30, 1956, Serial No. 619,291

4 Claims. (Cl. 292332) This invention relates to a latching mechanism for doors and the like, particularly for the doors of domestic appliances such as refrigerators, freezers, ovens, and washers.

.A first object of the invention is to provide a mechanism wherein latching and unlatching of a door occurs automatically and safely, upon a simple push against the outside of the door for latching or against the inside for unlatching.

A related object is to effect positive and smooth latching orjunlatching of the mechanism by merely pushing orpulling a rigid handle, rigidly secured to the door.

Another object is to latch the mechanism securelywhenever the door receives a closing impulse, either forcibly or .slight.

Another object is to provide for positive closing and filming-of the .door by adequate but moderate forces.

A related object is to provide a mechanism whereby adoor may be opened easily, even by children, and particularly in event of an emergency.

In connection with these objects the invention involves a novel combination of a constant-force door-latch and a low-pressure door-gasket.

Another object is to prevent a door from being left partly open by inadvertence. For this purpose, it is a particular object to trigger the automatic release of a substantial pull-in or latching force by manual application of a slight inward push. A related, particular object is to automatically store this force in the mechanism by theopening of the door.

Another object is to prevent a door from bouncing back when it is slammed. For this as well as for other purposes, it is an object to provide a long travelling path for certain parts of the mechanism and substantially constant forces acting on said parts, over major portions of thus far he provided in combination with the prevention of rebound on slamming; and other conflicts and problerns are known to the art. It is an object of this invention to resolve such conflicts and problems.

One aspect of a preferred embodiment of the invention can briefly be described by saying that it provides a bolt, adapted to engage a strike or keeper, the bolt being seeured to the door by a linkage system including three mutually interconnected and mutually shiftable pivot means. One such pivot means is interposed between the bolt and a support housing for the same, another 'between the bolt and an over-the-center toggle, and .the third between this toggle and the support housing. .Another important feature is that special guide or shiftcontrol means .are incorporated in the motion control structure, between the bolt and the two aforementioned parts directly connected therewith, so as to render the bolt able to pivot in an extended position but unable to pivot in retracted or partly retracted positions, while keeping it able to slide or shift widely, by or against certain forces, in all of its. operative positions. it is by this and equivalent combinations of motion controls that all of the above mentioned objects have been achieved. Details will be understood most readily upon a study of the complete disclosure which follows, with reference -to the drawing, wherein Figure l is a perspective front view of a refrigerator or freezer, with its door opened to show exposed parts of the latch, and Figure 2.is a perspective view, on a larger scale, of the bolt assembly, forming part of the latch, removed from said door wherein it is normally mounted.

Figure 3 is a plan view of the mechanism, in open position, and Figure 4 is a similar but more diagrammatic view, showing the mechanism in closed position.

Figures 5 to 8 are partial diagrams, in plan view, of the mechanism in successive positions intermediate those of Figures 3 and 4.; Figure 9 is a graph of certain measured forces, encountered when the mechanism moves through the' positions of Figures 7 and 8; and Figure 9A is a similar graph, schematically representing such forces in a more comprehensive manner.

Figures 10 and 1-1 are diagrammatic views, generally similar to those of Figures 3 and 4, respectively, but showing a modified mechanism.

Referring first'to Figure 1; the refrigerator cabinet has a front door 12 which may be provided with storage trays 13 in the now usual manner. This door can be opened and closed by simply pulling and pushing -a handle .14, which forms a rigid structure, rigidly secured to the front of the door. For normally holding the door closed, there is provided a bolt assembly 15, which may cooperate with a conventional strike or keeper 16 and which is automatically latched and unlatched when the doorcloses and opens.

This bolt assembly 15 is best shown in .Figure 2. It is held together by a bolt housing 17,, comprising two flat and identical plates and suitable web structure between them; it will suifice to describe one of these plates. A bolt 19 is slidable in a slot 20 which is formed in said plate or housing. There is a toggle linkage 21, which in this figure :is visible in part; the figure also shows a .pair of toggle pivot members 22 23, rigidly secured to oppo site ends of the housing. The bolt 19 has a slot 24 in engagement with one of these pivot members, 22, which member accordingly may be designated as a pivot pin slidable relative to one of the parts pivoted thereon. An additional, similar pin 25 is in engagement with the housing slot 20, while being secured to the bolt 19. Thus the bolt 19 and housing 17 are in engagement with one another by two sliding pivot pins 22, 25: the bolt pin;

19 relative to housing 17. The housing pin 22, as mentioned, also serves as a toggle pivot; in addition, the bolt pivot 25 is slidable not only relative to the housing but also relative to a part of the toggle, as will be explained hereinafter.

The strike 16 (Figure 1) is engageable with an open slot 26 in the exposed part of the bolt 19 (Figure 2). Figure 3 shows this engagement, as well as other details of the mechanism, to better advantage. The strike 16 provides a strike roller 27, the diameter of which is slightly smaller than the slot 26 is wide. This roller is pivoted on a bracket 28 which is secured to the side wall 29 of the cabinet by fastening means 30, adjacent the front and breaker strip 31 of the cabinet, reinforced as at 29A.

The latch mechanism 15, 16, as indicated by Figure 3, may be surrounded by the sealing gasket 32 which protects the inside of the cabinet from the heat, humidity and dust of the outside. As further shown in this figure, the door 12 comprises an outer shell 33 and an inner liner 34, with suitable spacing means 35 therebetween. A compact body 36 of heat-insulating material is incorporated in the door between members 33, 34; and similar material 37 is provided in the cabinet walls. A recess 38 in the body 36 of door-insulating material accommodates the bolt mechanism 15. This recess is slightly wider than the bolt housing 17 is long (Figure 3) and slightly higher than this housing is high, see dimension H (Figure 2); and a relatively thin body of insulating material, not shown, may line the walls of this recess. Within the recess (Figure 3), the bolt housing 17 is secured to a suitable support 39 which in turn is secured to the inside of the door shell '33. The entire bolt mechanism 15 is substantially concealed within recess 38 in the door, except that the bolt 19, at least in one position thereof, extends partly through an opening 40 in the door liner 34. In the position of Figure 4, the strike 16 extends through this opening into the recess.

Details of the bolt control toggle 21 are best shown in Figures 3 and 4. They comprise a first toggle link 211, pivoted to the housing 17 by the pin 22, and a second toggle link 212, pivoted to the housing 17 by the pin 23 and slidable relative to the same by means of a slot 213 in this link. A center pivot 214 interconnects the toggle links 211, 212; and a toggle spring 215 may be coiled around the link 212 between the pin 23 and a shoulder of said link. The toggle spring loads the toggle links by a force of compression, so that the links tend to move the toggle center pivot 214 away from the centerline AA between the toggle end pivots 22, 23. The links are free to move across this line, thereby providing an over-center toggle, with full retraction at the centerline with a substantially extended position forwardly of the axis (Figure 4) and a less extended position rearwardly of the axis (Figure 3).

The interconnection between the bolt and its motion control members, according to this invention, is a particular one, the bolt being slidable with respect to the housing and with respect to the toggle, and being pivotable in one terminal position of the sliding movements thereof. For these purposes the bolt is held (1) to the housing 17, by slots 20, 24 and pins 22 and 25, and (2) to an ear and cam section 216 of toggle link 211, by pin 25.

In Figure 4 the outline of the bolt-engaging toggle member 211 is diagrammatically emphasized by the use of a relatively heavyline. This representation is used in order to assist the reader in visualizing the form and arrangement of this important part. Figure 4 also shows certain structural details of the bolt-engaging toggle member 211, particularly in the ear and cam section 216 of this member. This section has inner and outer cam surfaces 217, 218, both engageable with the bolt pivot pin 25 and forming an open slot 219.

The system of three shiftable pivot means, initially mentioned, comprises: (1) the inner part 251 of the pivot pin 25, between the bolt and the housing, which part is adapted to slide or roll along the slot 20, (2) the outer part 252 of this pin 25, between the bolt and the toggle,

0 Figure 9, curve 91.

which part is adapted to' slide or roll along the slot 219, and (3) the pivot pin 23 between the toggle and the housing, which can slide or roll along the slot 213. A fourth sliding pin 22 has been mentioned above.

Operation of the present device, when closing the door, starts in the position of Figure 3 and continues through the positions of Figures 5, 6, 7 and 8, in this sequence, until the door is closed as indicated in Figure 4. The opening of the door can be visualized by considering these figures in the reverse sequence, with certain modifications as will be pointed out hereinafter.

Referring particularly to Figures 5 and 6: the closing operation of the latch begins when the position of Figure 5 has been established, by moving, pushing or slamming the door toward closed position. Therefollows a rocking motion of the bolt 19, caused by the engagement be tween the strike roller 27 and a curved cam surface 261 opposite this roller, in the slot 26 of the bolt, which serves to start the triggering of the latch. The curvature of the surface 261 is such that the roller 27, when contacting the surface, urges the bolt to rock counterclockwise to'ward the left; the bolt (Figure 3) being allowed by a small lateral recess in the bolt slot 24, engaging the pin 22, to pivot on the guide pin 25. The original, right-hand bolt position (Figures 3, 5) is normally ensured, when the door is open, by means of a small spring 262, tensioned between the bolt and the housing thereof. The force of this spring is readily overcome whenever the strike engages the bolt, as the door closes. When, accordingly, the triggering has been initiated (Figure 6), a projecting bolt portion 263, cooperating to define the open slot 26, is inserted behind the strike roller 27, for positive bolt-keeper engagement later on.

For the moment the operation continues by changing to the position of Figure 7. The bolt pivot 25, still actuated by the strike roller 27, moves forwardly from the position of Figure 3 along the rearward part (in the drawing, the upper part) of the slot 20 and engages the outer cam surface 218 of the ear 216 of toggle link 211, thereby tending to rotate this link clockwise, against the pressure of the spring 215. A small pressure at 25, 218 sufiices, as the surface 218 has a substantial moment arm about pivot 22, while the rearwardly extended toggle has only a much smaller moment arm about this pivot. Thus the link 211 actually rotates, the to'ggle moves across the center and the triggering is completed.

As may be noted from Figures 7 and 8 the ensuing pull-in operation or automatic completion of the latching process involves further clockwise rotation of the link 211, this rotation now being effected, no longer resisted, by the spring 215, and being effective upon, no longer actuated by, the bolt pivot pin 25. This pivot pin now slides or rolls along the front part (in the drawing, the lower part) of the slot 20, thereby tending to move the bolt 19 forwardly, but actually, due to the bolt-keeper engagement, moving the door rearwardly toward the cabinet. This rearward or pull-in action results in firm closure of the door and compression of the gasket 32.

The pull-in force, provided by the toggle spring 215 and indirectly acting on the door 12, can be measured by well-known test apparatus external of the door; and the exact results of such a measurement are plotted in In this graph, the left-hand intersection of the abscissa and the curve 91 represents the above-mentioned start of the pull-in operation typical for a household refrigerator door equipped with the new latch, while the zero point represents the completely closed position of this door. The horizontal distances represent the distances of the door from the completely closed position and the vertical distances represent the pull-in forces. It will be noted that the measured pull-in force, during practically the entire pull-in travel, is sub! stantially constant or uniform, that is, two pounds with a tolerance of not more than plus or minus fifty percent.

This uniformity is achieved by (1) making the angular movement of the cam surface 217 proportional to the linear forward movement of the roller 252, and (2) making the force component acting on this roller in the direction of said movement practically uniform, with due allowance for spring expansion, leverage forces, moment arms about the toggle pivots and other factors such as frictional forces and forces of inertia. These details will be understood by persons skilled in the art, in the light of this disclosure.

Referring now to the opening of the door: this operation starts in the closed position of Figure 4 and then proceeds through the positions of Figures 8, 7 and 6 to open positions like that of Figure 3. In this latter position the door has been opened and the bolt has been "cocked or loaded with energy for subsequent triggering.

.While Figure 8 may be considered as indicating a position of the toggle, cam, bolt and connected parts either in closing or in opening the door, the forces involved at this point in the opening of the door have been found to differ widely from those involved in closing it. This seems to be due to frictional and other forces.

In order to explain these forces, reference is made to Figures 9 and 9A. The first of these figures illustrates actually measured and automatically recorded forces and reactions, encountered in a typical application of the present mechanism. The horizontal coordinates are graduated in fractional inches of movement of the door between a zero position (Figure 4) and a position directly preceding that of Figure 3, wherein the door has been opened by .9 of an inch. The vertical coordinate is graduated in pounds, meaning either pounds of door-closing force, while closing, or pounds of reaction to a door-opening force, while opening the door. The curve 91 was automatically written from left to right, whereas the curve 92 was automatically written from right to left.

In substance, accordingly, the curve 92 indicates the loading of spring 215 with energy, incident to that manual displacement of the door which displaces the toggle from the position of Figure 4 to the center position. The curve 91 indicates'an energy discharge of the spring 215, incident to the opposite movement from the center position AA to the position shown in Figure 4.

Additional curves are shown in Figure 9A. The curve 93 indicates that small amount of energy which is discharged during the interval when the door moves from the almost open position of Figure 5 into the full-open position of Figure 3, and when it thereby moves the toggle 21 from the center position AA into the position of Figure 3, slightly beyond the center. Curve 94 indicates the reverse process of triggering the latch. Curve 95 indicates the amounts of energy stored in the gasket 32 at each position of the door. This rises gradually as gasket portions of the hinge side and of the top and bottom of the door are compressed; and starting at some point (96) this curve rises more steeply as gasket portions of the latch side of the door also begin to be compressed.

It will now be understood that the area under curve 92 can be divided into different portions, indicated by the numerals 97, 98, 99 and 100. The first of these indicates the useful energy, expended by spring 215 in closing the door and compressing gasket 32. Area 98 indicates, in a schematic way, the energy expended by the spring in overcoming friction of the mechanism while closing the door; 99 similarly relates to friction overcome by the operator while opening the door; and 100 represents in a general way some other expenditures of force, such as the tensioning of the small spring 262.

Manifestly, the arrangement shown can be modified in various ways, for instance as to the ratio of net closing forces and frictional forces. The point of importance for the present invention is that in spite of the complex process, the practically significant portions of the energy 6 storing and discharging processes, represented by the curves 91 and 92, involve practically uniform forces, as indicated by the substantially parallel, horizontal diree tions of these two curves throughout maj'or parts of their length.

Brief rsum of the basic operation of the new latch:

When the door bolt first makes contact with the strike (Figure 5), the door is open by about three-quarters of an inch (Figure 9). An inward triggering force of a few ounces is then sufficient to release (Figure 6) a rapid pullin action (Figures 7, 8) which closes the door with the equivalent of a constant force of about two pounds (Figure 9). With the door either closing (Figure 8) or closed (Figure 4) a mere reversal and slight overbalancing of this constant force are insufficient to open the door; it is necessary to apply a constant force of about ten pounds (Figure 9) to reverse the toggle (Figures 7, 6) and thereby to cock the latch and open the door (Figure 3).

Special situations and problems, such as are sometimes encountered in the use of latches, are as effectively handled by the new mechanism as are the basic operations, explained up to this point.

In this further connection it may be considered, for instance, that due to heavy loading of trays 13 (Figure 1), the door structure 12 is distorted and the original relative positioning of the bolt 19 and strike 16 is gradually changed in either forward--rearward or lateral directions or both, as indicated for instance at 27A, 278 (Figure 5). The opening 264 of the slot 26 in bolt 19 can be made large enough, according to this invention, to allow the strike roller 27 to enter the slot even in case of substantial changes of said original positioning; and the curved surface 261 can be shaped so that even in case of such a change, positive triggering can be effected. The only effect of a relative displacement of the strike roller, for instance from 27 to 27a, is that the trigger movement of the bolt may involve a somewhat longer angular and forward stroke. It is in order to avoid premature triggering of the pull-in release, prior to the positive latching (Figure 6), that the cam surface 261 is curved in the manner as shown, that is, approximately normal to the slots 20, 24 opposite the projection 263 and with rearward concavity toward the opening 264. In prior latches, cam surfaces corresponding to surface 261 were usually or necessarily designed to suit other operating requirements; as a result, only minute displacements of original or theoretical bolt-strike alignments could be allowed. The new bolt, which operates even in case of serious misalignment, adds materially to the useful service life of an appliance cabinet.

A further special problem, encountered in previous selfclosing latches, was connected with accidental tripping of the cocked bolt when the door was in open position. This problem is substantially solved by that feature of the new latch according to which two distinct movements of the bolt are required for triggering: the rocking movement, counteracted by spring 262 (Figures 5, 6) and the initial sliding movement, counteracted by spring 215 (Figures 6, 7). Thus the bolt cannot be triggered manually except by a very specific sequence of operations, which would not occur because of mere inadvertence. Even a definite attempt to manually press the projecting part of bolt 19 into the slot 40 (Figure 3) leads to no trigger release, unless this part has previously been moved to the left.

Referring now to the door gasket combined with the door and the latch mechanism: this gasket, when made in a form of the type shown, cooperates with the latch in facilitating the easy opening and firm closing of the door.

There is shown, as a preferred example (Figure 3) a gasket 32 of the type described in my copending application Serial No. 554,511, filed May 14, 1956, entitled Closure Seal" and assigned to the assignee of this invention. Such a gasket may comprise: mounting means 3.21; a sealing strip 332 spaced above and approximately parallel to said means; a relatively thick side strip 323 interconnecting the members 321, 322, with a recess 324 adjacent one of the junctures of such members for'flexing the sealing strip rather than the side strip; and a second, relatively thin side strip 325 for supporting the sealing strip. The space between the elements 321, 322, 323, 325 may either be hollow or may be filled with suitable material. The mounting means 321 may provide a fiat, hollow space, parallel to the space 326, between the strips 322, 325, etc. Such a gasket has the advantage that it provides excellent sealing, throughout a long service life, with a very low sealing pressure, for instance a pressure of one to two pounds; and such pressure is desirably and effectively provided by the present latch, when the door is closed (Figure 9).

Other low-pressure gaskets can also be used in combination with the present latch; and the low-pressure feature of any suitable gasket can be coordinated with the low, constant force characteristics of the latch in approximately the same manner as in the case of gasket 32. In other words, it is desirable than there be used a gasket and latch combination of such kind that the storage and the discharge of latch energy-the latter including gasketcompressing energy, results in operations of the type indicated by curves 91, 92 and 95 in Figures 9 and 9A, which curves are substantially parallel with and suitably spaced from one another. For these purposes I have found it particularly desirable to utilize a hollow gasket, of a general arrangement and form substantially as Shown. If, by contrast, the gasket had the formerly usual form of a solid rubber strip or the like, with compressional forces varying widely during the course of the compressing and decompressing operations, it was necessary to compensate for such variations by relatively complex modifications of the cam profile 217, or similar expedients,

In this connection attention should also be given to a final, important operating features of the new latch, re lating to closure of the door by slamming it, leading to momentary, forcible compression of the gasket and a tendency toward resilient bouncing back.

Heretofore, in case that an automatically latching and unlatching door was slammed, there was little or no protection against such bouncing back. Some doors bounced back when slammed very hard, others when slammed with moderate speed; all or at least most of them were frequently left wide open as a result of these conditions. While bolt elements similar to that shown at 263 were conventionally used, they operated less efficiently than they do in accordance herewith.

In this connection it must be realized that, due to the engagement between the strike roller 27 and the curved bolt surface 265 (Figure 6) the impact between gasket 32 and the inturned flange 29A of outer shell 29 (Figure 4) is vibratory; it results in a cycle of vibratory, relative movements of strike roller 27 between bolt surface 261 and the opposite surface 265 on the front of the projecting bolt portion 263 (Figure 6). This latter surface should be inclined in a direction approximately parallel to that of the adjacent portion of the curved surface 261 (in order to ensure successful opening of the door at the moment when the, position of Figure 8 changes to that of Figure 3); therefore, when the slamming of the door leads to the position of Figure 6, not only the feeble spring 262 but also the impact between the strike roller 27 and surface 265 causes a strong tendency of the bolt to swing back, clockwise. It was largely due to tendencies of this kind, in prior mechanisms which provided for automatic unlatching in some operative phase, that the vibrations of the door, incident to slamming, were able to open the latch.

In the present design, by contrast, the clockwise swinging back of the bolt is prevented at all times when it can do any harm; swinging of the belt is allowed only in the 8 fully cooked position. More particularly, before any rebound force is created, the bolt has been triggered; that is it has been shifted part of the way into the recess 38.

undue friction and interference by dust and the like,

yet, even in the presence of such play, the considerable sliding apart of the guide pins, in their slots, causes the bolt to be held firmly against any substantial pivotal motion, as soon as a position such as that of Figure 7 has been established. Such holding then becomes even stronger during the further sliding of the bolt into the housing, so that practically no pivoting is possible at the time when a rebound force is encountered, that is, in the position of Figure 4.

Nor can this latter position be disturbed by rebound forces acting longitudinally of the bolt. The cooperation of the toggle 21 and cam mechanisms 217, 252 and 26, 27 (Figures 6, 7) counteracts forces of this kind, although it allows opening of the door by moderate static pressures (Figure 9), applied against the inside thereof. A sufiicient, static, forwardly directed force, for instance of about ten pounds as applied to the door, causes the overcenter motion against the force of the toggle spring. The rebound force, on the other hand, being generated by vibratory interaction of gasket and latch, as described above, is only cyclically active to attempt the rearward over-center motion. Intermittently, it allows at least partial re-expansion of spring 215, so that it achieves relatively little toward an actual over-center motion and opening of the door. It leads only to a short series of bursts of door-opening forces, the first few of which may momentarily exceed the constant ten pound door-opening reaction but the last of which approach zero, as the vibration decays. The details of the vibratory motion are dependent on factors such as the dimensions of door 12, the path of roller 27 between surfaces 261, 265, the path of pivot 25 along slot 20 and the vibratory characteristics of spring 215 and mainly of gasket 32, this latter element being effective also to damp the vibration of the door. The decay of the vibration can be caused to occur safely before the center position of the toggle has been reached because of a rebound.

Safe closure of the door is thus available when slamming the door at any speed to be considered in practice. Prior latch devices arranged for automatic latching and unlatching, among others, have given no such protection; and that was also true of substitutes such as the Wellknown magnetic door closers.

In the modified latch construction of Figures 10 and 11, there are used somewhat more complex forms of strike 16A and bolt mechanism 15A, in accordance with this invention.

Referring first to the modified strike 16A (Figure 11): The bracket supporting the strike roller 27 is here formed by a pair of arms 28A, 23B pivoted to one another by a strong pin 28C. These arms are normally held in aligned position by a torsion spring 28D cooperating with a stop mechanism 28E. In the event, however, that the bolt has been triggered in the open position of the door, in spite of the protection described above, the spring 28D allows the terminal bracket member 288 to rock about the pin 28C; and such rocking is here induced by forming the rearward surface 193 of the bolt 19A so as to cause clockwise swiveling of the arm 28B upon an impact 27, 19B. Rota tion of the bolt itself, in the triggered position, is prevented as in the embodiment described above, although the means used for this purpose may be different in the presen 5 In this latter connection it will be noted upon a com! parison of Figures 10 and 11, that the bolt 19A in this case is connected with a primary bolt housing 17A by a secondary bolt housing 17B; these two housings being permanently pivoted together at one end thereof by a pin 23A. This pin also serves as one of the end pins 22A, 23A of the toggle 21A, which in other respects may resemble the toggle 21 of the first embodiment.

The secondary bolt housing 17B, which constitutes one of the distinguishing features of the present embodiment, is permanently connected with the bolt 19A by a pivot 25A, while being 'shiftably connected with the center pivot 214 of the toggle by a slot 24A, suitably formed in this housing 17B. Shifting engagement between the bolt and the primary housing 17A is also provided, by a suitable cam surface 20A in or on the bolt and a roller 22B on the pin 22A.

The bolt, riding on the pin 25A, is biased toward this roller 223 by a torsion spring 25B.

It may be noted that there is again provided a system of at least three shiftable pivots between the bolt and the supporting door 12A: a pivot 25A between the bolt and the secondary support housing, this pivot being slidable along the primary support housing; a pivot 214 between the toggle and the secondary support housing, this further pivot being shiftahle in the slot formed in said housing; and the above-described pivot 23A between the toggle and the primary support housing, shiftable in the slot formed in the toggle.

It may further be noted that the member 17B may also be considered as a secondary bolt member, connected with the primary bolt member 19A; in substance, all of the distinguishing aspects of the invention, described above, will again be found to be present in the construction and operation of this embodiment. It is believed to be unnecessary to explain this operation of the modified latch in further detail herein, in view of the foregoing full description of the first mentioned and preferred embodiment and its operation.

While only two embodiments of the invention have been described, the details thereof are not to be construed as limitative of the invention except insofar as set forth in the following claims.

I claim:

1. An automatic latching mechanism comprising: a bolt housing having a guide slot therein; a bolt, having a body portion which also has a guide slot therein, said bolt having an end portion which has an open, transverse,

10 keeper-engaging slot, inclined relative to the guide slot of the bolt, so that engagement of the bolt with a keeper in one direction longitudinal of the guide slot urges the bolt to move in one direction lateral of the guide slots; means for resiliently urging the bolt in another direction, opposite to said one direction lateral of the guide slots; a

pair of pins, one on said housing for sliding engagement 9 with the slot of said bolt, the other on said bolt for sliding and pivoting engagement with the slot of said housing; said housing and bolt including means associated with said pins and slots, to generally prevent said moving of the bolt in said another direction opposite to said one direction lateral of the guide slots but to allow such moving, pursuant'to sliding of the bolt outwardly of the housing; a pair of toggle links, pivotally secured to said housing, one such link having engagement with said pin on said bolt and the other, in addition to the pivotal securement thereof, having slidable engagement with said housing; means for pivotally interconnecting said toggle links; and means for resiliently urging them into either of two over-center positions defined by the pivotal and slidable securement and connection of said links, for controlling said sliding of the bolt by the link having engagement with the pin on the bolt.

2. A latch mechanism as described in claim 1, wherein the first-named toggle link has a cam surface, adapted to contact the pin on said bolt and thereby providing said engagement with the bolt.

3. A mechanism as described in claim 1 wherein at least major portions of both of said guide slots are sub stantially straight and said transverse slot is slightly curved.

4. A mechanism as described in claim 3 wherein said guide slot in the bolt is substantially straight but has a short, transversely extending end portion to allow the pivoting of the bolt.

References Cited in the file of this patent UNITED STATES PATENTS 1,744,424 Trudeau J an. 21, 1930 2,016,519 Schmidt Oct. 8, 1935 2,355,895 Roberts Aug. 15, 1944 2,659,621 Jacobson Nov. 17, 1953 2,679,427 Johnson May 25, 1954

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