US3924886A

US3924886A - Sliding link safety latch

Info

Publication number: US3924886A
Application number: US436097A
Authority: US
Inventors: Branko Markovitch
Original assignee: Individual
Current assignee: Individual
Priority date: 1974-01-24
Filing date: 1974-01-24
Publication date: 1975-12-09
Anticipated expiration: 1992-12-09
Also published as: GB1486378A

Abstract

Safety latch has a base securable to a door and a catchplate securable to the adjacent doorframe, or vice versa. An intermediate link is slidably and pivotally mounted in the base, and a latch link is pivotally mounted to the intermediate link and selectively engageable in the catchplate. When the latch link and intermediate link are folded into the base and are slid to the non-engagement position, they are locked in place. When they are slid to a position where the latch link is engaged with the latchplate, the links can unfold out to permit the door to open a limited amount.

Description

United States Patent 1191 Markovitch 45] D 9, 1975 SLIDING LINK SAFETY LATCH 2,462,282 2/1949 Pickford 292/247 x [75] Inventor: Branko Markovitch, Hawthorne, 3,563,592 2/1971 Preston 292/263 Cahf' Primary ExaminerRichard E. Moore [73] Asslgnee: Samuel P. Simmons, Lomita, Calif. Attorney, Agent, or FirmJoh1n Holtrichter, Jr.

22 Filed: 24 7 1 19 4 57 ABSTRACT [21] Appl' 436097 Safety latch has a base securable to a door and a catchplate securable to the adjacent doorframe, or 52 US. Cl 292/263; 70/93 viee verea- An intermediate link is Slidably and p 51 Int. cl. E05C 17/48 y mounted in the base, and a lateh link is pivetally [58] Field of S h 292/113 263 247 mounted to the intermediate link and selectively en- 7O/93 gageable in the catchplate. When the latch link and intermediate link are folded into the base and are slid [56] Ref Ci d to the non-engagement position, they are locked in UNITED STATES PATENTS place. When they are slid to a position where the latch 526,164 9/1894 Phelps 292/263 hnk ls engaged wlth the latchplate the hnks can un- 906,305 12/1908 Schacht 2,407,900 9/1946 Paul 70/93 fold out to permit the door to open a limited amount.

12 Claims, 10 Drawing Figures SLIDING LINK SAFETY LATCH BACKGROUND OF THE INVENTION This invention is directed to a safety latch for fastening to a door to permit the door to be opened a limited distance.

When the security of person or property is involved, door locks and latches are required. Many types of locks have been created to retain doors in closed position, except at the manipulation of the owner. With respect to safety latches, there are situations where the person inside desires to have his door open only a limited amount. In these cases, ventilation or viewing through the limited door opening are possible. For many years, chains have been employed in this service. Chains are disadvantageous because they are difficult to manipulate noisy in operation, and noisy when they are hooked up on the door and the door is in normal use. Furthermore, the chain structures are usually low in strength due to the end fittings thereon and the fact that such chain structures are generally attached to relatively weak door moldings. Thus, there is need for an improved safety latch structure.

SUMMARY OF THE INVENTION In order to aid in the understanding of this invention, it can be stated in essentially summary form that it is directed to a safety latch for mounting upon a door member and upon a door frame member. The safety latch has a base securable to one of the door members, as well as a latchplate securable to the other door member. An intermediate link slidably mounted in the base pivotally carries a latch link which is engageable with a latchplate so that, when it is engaged, the structures are coupled together and swing out to limit the opening of the door.

It is thus an object of this invention to provide a safety latch of conveniently operable and economic construction which provides full security.

It is another object to provide a safety latch structure which has a slidable intermediate link which locks the intermediate link and latch link in the base during nonuse of the safety latch and which permits sliding of the intermediate link out of lock position to a position where the latch link engages the latchplate.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages thereof, may best be understood by making reference to the following description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like elements in the several views.

BRIEF DESCRIPTION OF THE DRAWING FIG. 5 is a perspective view of another embodiment of the safety latch and door lock of this invention;

FIG. 6 is a section therethrough similar in aspect to the section of FIG. 3;

FIG. 7 is a side-elevational view of another embodiment of the safety latch of this invention;

FIG. 8 is a section therethrough of similar aspect to the section of FIG. 6;

FIG. 9 is a bottom-plan view of the safety latch of FIG. 7, with the intermediate link and latch link extended; and I FIG. 10 is a perspective view of a portion of a latchplate adapted for use with the latch links shown in the embodiments of FIGS. 59.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 through 4 show a presently preferred embodiment of safety latch 10 of this invention. Safety latch 10 has three major parts. Base 12 is arranged for securement by any conventional means such as screws 12 on door 14 adjacent the edge thereof away from the door hinges. Latchplate 16 is secured by means of screws, for example, against the doorframe 18 adjacent the location of base 12. I

Intermediate link 20 carries sliding pivot pin 22 through its inner end. Sliding pivot pin 22 also engages through

slots

24 and 26 in the upturned sides of base 12; thus when intermediate link 20 lies substantially parallel to the bottom of base 12, its pin 22 can slide along the length of

slots

24 and 26. Spring 28 is secured to the base 12 by a rivet 29 and engages against pin 22 to resiliently detent the pin in either of its end positions along the

slots

24 and 26. In FIGS. 1 and 2, the intermediate link is positioned in its retracted rightmost position. In FIGS. 3 and 4, pivot pin 22 is detented into the left end of the slots.

Hinge pin 30 pivotally interengages' between the outer end of intermediate link 20 and the inner end of latch link 32, and handle 34 is secured to the outside surface of latch link 32 for convenience in manual engagement. In this embodiment, the outer end of latch link 32 has a positive tee 36 which engages into a tee slot 38 in a hollow cylindrical end portion 39 of the latchplate 16 However, in many applications it may be desirable that the link carry a tee slot and thelatchplate carry the tee, as illustrated in FIGS. 5-10, for example.

The parts are dimensioned, as seen in FIGS. l and 2, so that latch link 32 folds to overlie intermediate link 20 and lie between the sides of base 12. When. folded into such position andslid to the right, as shown in tently come loose. When they are moved to the left, as

seen in FIG. 3, latchplate 16 is positioned so that tee 36 enters tee slot 38 to lock therein, see FIG. 3. From this position, the links unfold as the door is swung open to the extent permitted by the links. The width of the tee slot retains tee 30 as long as the latch link is swung out. Thus, the secure outer limit for door-hinging is achieved.

Safety latch 44 is generally illustrated in FIGS. 5 and 6. It is another species of the safety latch and illustrates a structure having base 46, intermediate link 48, and

3 latch link 50 similarly interrelated to the corresponding parts in safety latch 10. The same sliding pivot pin 22 and hinge pin 30 are involved. The outer ends of latch link 50 have a tee slot 51 therein for engagement on a corresponding tee 52 in the associated latchplate 53, as shown in FIG. 10.

The principal difference between safety latch 10 an safety latch 44 is in the locking structure which retains the links in place in the base when they are not needed for latching duty. Sliding lock 54 slidably held in base slots 55 has a locking cover 56 which engages over latch link 50 when the entire structure is in the inoperative, locked position.

When engagement of latch link 50 with its corresponding latchplate 53 is desired in order to prevent the door from being opened, sliding lock 54 is slid to the left by manual engagement with its locking handle 58 to the position shown in FIGS. and 6. This sliding motion moves the intermediate link 48 and latch link 50 halfway to the left to engage in the slots 51 defining the tee 52 in the latchplate 53. This serves as a positive lock for the door because the links cannot swing out; they are held down by locking cover 56. When safety latching is desired, the links are pressed to the left by means of link handle 50a to be detented in the left position by a detent spring 57. This motion moves latch link 50 into its latch-engagement position. When sliding lock 54 is moved to the right, the hinge pin junction between the links is released and the links can swing out to a door-limiting position. Thus in the safety latch 44, sliding lock 54 retains the link structure in folded position during nonuse and selectively retains the links in folded position after engagement of the latch link 50 to serve as a closed door-retaining latch. As can be seen in FIG. 6, the spring 57 is retained in position by a rivet 59 and has two

lobes

57a and 57b to detent the opposite positions of the links. Although not necessarily essential to the basic operation of the present invention, in all embodiments of the invention the latch link is preferably biased by the detent spring toward the latchplate when the latch link is moved into its latchplate engagement position, and the distance between the plate and the base is such that the outer extremity of the latch link contacts the latchplate and exerts a pressure against it caused by the bias provided by the spring.

FIGS. 7 through 9 illustrate safety latch 60, which is another embodiment of the safety latch of this invention. Safety latch 60 has the same basic parts as the previously described embodiments, namely a base 62 with screw-accepting lobes 63, intermediate link-64, and a latch link 66. Intermediate link 64 is secured to the base by means of sliding pivot pin 68 engaged in slots 69 of the base. Hinge pin 70 hinges latch link 66 to the outer end of the intermediate link 64. When the structure is slid to the latching position, to the left, the latch link 66 extends into engagement with its corresponding latchplate 53 (see FIG. under bias pressure provided by detent spring 71. When latched in that manner, the links can unfold to limit the amount of door opening, as previously described with respect to safety latch 10. When folded, the links are slid to the right, to the position shown in FIG. 7, where locking is accomplished. Locking of the links in the folded position is managed by means of lock pin 72 which has head 74 thereon over a reduced diameter neck 75. The head passes through, and the neck engages, in keyhole slot 76 to hold the links in position. Thus, sliding the links with respect to the base locks andunlocks them by 4 means of the keyhole slot structure. An elongated slot 78 is provided in the intermediate link 64 in order to allow free movement of this link without engagement with the lock pin 72.

From the foregoing it should be evident that there has been described safety latches which are conveniently operable and of economic construction and which provide full security while allowing a door to be opened a limited amount.

It should be understood that the materials used to fabricate the various embodiments of the invention are not critical and any material exhibiting desired qualities such as ease of fabrication, strength, etc., may be used. For example, solid or brass-plated steel or an aluminum alloy and possibly even some synthetic materials may be utilized. Furthermore, any conventional manufacturing process such as casting, machining, stamping, etc., may be used. I i I It should also be understood that although several embodiments of the invention have been described, the invention is susceptible to numerous modifications and embodiments within the ability of those skilled in the art and without the exercise of the inventive faculty. For example, the latchplate may bemounted on the door and the safety latch link mechanism may be mounted on the door frame. Accordingly, such modifications and embodiments are deemed to be within the spirit, scope and contemplation of this invention.

I claim:

l. A safety latch for mounting upon a door member and upon an associated door frame member to selectively permit the door to swing freely open or to permit the door to swing open a positively limited amount, said safety latch comprising:

a stationary latchplate for mounting on one of the door members, said latchplate having an engagement opening therein;

a base for mounting upon the other door member;

an intermediate link slidably and pivotally mounted with respect to said base;

a latch link pivotally mounted with respect to said intermediate link, said latch link having a nose for engagement into said engagement opening of said latchplate only when the door is in closed position so that said intermediate link and said latch link unfold and pivot with respect to each other and with respect to said base to limit door opening.

2. The safety latch of claim 1 wherein a sliding pivot pin interengages between said intermediate link and said base to permit sliding and pivoting of said intermediate link with respect to said base.

3. The safety latch of claim I wherein a stop is secured to said base and said latch link is retained by said stop with respect to said base when said links are folded and slid in a retracted position with respectto said base.

4. The safety latch of claim 3 wherein said stop comprises a cross stop extending across the top of said base and engaging over said latch link when in its folded retracted position.

5. The safety latch of claim 4 wherein said stop is fixed on said base.

6. The safety latch of claim 4 wherein said stop is slidably movable on said base so that said stop can be moved to a position wherein said engagement nose on said latch link is extended into said engagement opening in said latchplate and said latch link is retained by said stop in folded position with respect to said base to hold the door in its closed position.

7. The safety latch of claim 6 wherein said engagement opening in said latchplate and said engagement nose on said latch link are in the form of a tee and a tee slot constructed so that said engagement nose can engage into said engagement opening when the door is closed, and said engagement nose is prevented from disengagement from said engagement opening when the door is opened.

8. The safety latch of claim 7 wherein the sliding pivot pin interengages between said intermediate link and said base to permit sliding and pivoting of said intermediate link with respect to said base.

9. The safety latch of claim 3 wherein said stop comprises a post mounted on said base, said post having a head thereon, said head engaging through a keyhole slot in said latch link so that said latch link is retained with respect to said base when said latch link is in its retracted position and said latch link is free to swing out of said base when said latch link is in its extended positron.

10. The safety latch of claim 1, also comprising spring means mounted on said base and slidably cooperating with said intermediate link for indexing and biasing the sliding movement of said intermediate link.

11. The safety latch of claim 1, wherein said engagement opening in said latchplate is in the form of a tee and said engagement nose on said latch link is in the form of a tee slot, said tee and tee slot being constructed so that said engagement nose can engage said engagement opening when the door is closed, and said engagement nose is prevented from disengagement from said engagement opening when the door is opened.

12. The safety latch of claim 1, wherein said engagement opening in said latchplate is in the fonn of a tee slot and said engagement nose on said latch link is in the form of a tee, said tee slot and tee being constructed so that said engagement nose can engage said engagement opening when the door is closed, and said engagement nose is prevented from disengagement from said engagement opening when the door is opened.

Claims

1. A safety latch for mounting upon a door member and upon an associated door frame member to selectively permit the door to swing freely open or to permit the door to swing open a positively limited amount, said safety latch comprising: a stationary latchplate for mounting on one of the door members, said latchplate having an engagement opening therein; a base for mounting upon the other door member; an intermediate link slidably and pivotally mounted with respect to said base; a latch link pivotally mounted with respect to said intermediate link, said latch link having a nose for engagement into said engagement opening of said latchplate only when the door is in closed position so that said intermediate link and said latch link unfold and pivot with respect to each other and with respect to said base to limit door opening.

3. The safety latch of claim 1 wherein a stop is secured to said base and said latch link is retained by said stop with respect to said base when said links are folded and slid in a retracted position with respect to said base.

5. The safety latch of claim 4 wherein said stop is fixed on said base.

9. The safety latch of claim 3 wherein said stop comprises a post mounted on said base, said post having a head thereon, said head engaging through a keyhole slot in said latch link so that said latch link is retained with respect to said base when said latch link is in its retracted position and said latch link is free to swing out of said base when said latch link is in its extended position.

12. The safety latch of claim 1, wherein said engagement opening in said latchplate is in the form of a tee slot and said engagement nose on said latch link is in the form of a tee, said tee slot and tee being constructed so that said engagement nose can engage said engagement opening when the door is closed, and said engagement nose is prevented from disengagement from said engagement opening when the door is opened.