US3924885A

US3924885A - Safety latch

Info

Publication number: US3924885A
Application number: US436099A
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: US3913961A; GB1486665A

Abstract

Safety latch has a base securable to a door and a latchplate securable to a doorframe, or vice versa. An intermediate link is pivoted to the base and a latch link is slidably mounted on the intermediate link so the intermediate link can interengage its nose with the latchplate to permit the door to swing open only a limited extent.

Description

ited States Patent 1 1 [111 3,924,885

Markovitch Dec. 9, 1975 SAFETY LATCH 1,499,087 6/1924 Weber 292/275 x 1,853,517 4/1932 Finnerty 292/275 [75] inventor" g fi Markovltch Hawthorne 1,961,472 6/1934 Abrahams 292/263 [73] Assignee: Samuel P. Simmons, Lomita, Calif. Primary Examiner-RiChard E- MOOre [22] Filed, Jan 24 1974 Attorney, Agent, or FirmJohn Holtrichter, Jr.

[21] Appl. No.: 436,099 [57] ABSTRACT Safety latch has a base securable to a door and a 52 us. 01. 292/262 p securable to a fram or vice versa. An 51 Int. c1. E050 17/04 intermediate link is pivoted to the base and a latch Field Of Search 292/114, 262, 275, 338 link is slidably mounted on the intermediate link so the intermediate link can interengage its nose with the [56] References Cit d latchplate to permit the door to swing open only a lim- UNITED STATES PATENTS extent 1,427,730 8/1922 Fournier 292/268 X 6 Claims, 7 Drawing Figures SAFETY LATCH BACKGROUND OF THE INVENTION a door to be permitted to swing open a limited amount and prevent it form swinging farther open. Such limited swinging permits ventilation and permits inspection outward through the limited door opening without access. Accordingly, a number of structures have been created for stopping a door from fully opening.

For the most part, these prior art structures comprise a chain fixed at one end to a bracket, and detachably secured at the other end to another bracket. These brackets are then attached to the door and the adjacent structure. Some of teh disadvantages include the noisiness of the chain, the weakness of the total structure which is usually in the end attachment, and the fact that the end attachment on the doorframe side is usually attached to the door trim, rather than a solid structural part. Therefore, they are not as reliable and strong as might be desired.

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 which has a base for mounting upon a door and a latchplate for mounting upon the adjacent doorframe. A link is pivoted to the base and a latch link having an engagement nose thereon is slidably mounted on that link. An engagement nose on the latch link engages into an engagement opening in the latchplate to limit door opening.

It is thus an object of this invention to provide a safety latch which is firmly mounted on structural parts of both the door and the doorframe so that the limited door opening is established by strong adjacent parts.

It is another object to provide a safety latch wherein a swingout telescopic structure interengages between the door and the doorframe, with positive maximum telescopic limits which limit door opening.

It is yet another object to provide a safety latch wherein the engagement nose mounted upon the doormounted portion can engage and be disengaged from the engagement opening in the doorframe-mounted latchplate only when the door is in closed position and, when the door is in open position, the engagement nose is locked within the engagement opening.

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 drawing, in which like reference characters refer to like elements in the several views.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a front-elevational view of the safety latch showing the latch in the disengaged position; I

FIG. 2 is a view similar to FIG. 1 showing the engagement nose engaged in the latchplate, but with the door still closed;

FIG. 3 is a top-plan view of the safety latch with the doorframe and door taken in section showing the structure with the door opened to the limit permitted by the safety latch;

FIG. 4 is a section through the door-mounted portion of the latch with the latch in the retracted position, substantially taken along the line 4-4 of FIG. 1;

FIG. 5 is a section taken generally along the same plane as FIG. 4 showing the latch in the extended positlon;

FIG. 6 is a plan view of a latchplate with no form of engagement opening; and

FIG. 7 is a plan view of a link and a latchplate having a modified form of opening.

DESCRIPTION OF THE PREFERRED EMBODIMENT The safety latch 10 of this invention is comprised of a structure 12 for mounting upon a door, and a latchplate 14 for mounting upon a doorframe. This latchplate 14 has a thin plate 16 for mounting with screws upon the door jamb similar to a conventional latchplate. Secure mounting is schieved by placing sturdy screws 17 through plate 16 into the solid wood of the doorframe. This inner edge of plate 16 carries a rolled end 18 which is tubular and which has an engagement opening 20 therein. The purpose of the particular shape of the engagement opening described will become apparent below.

Structure 12 for mounting upon the door is shown in FIG. 3 as being mounted upon door 22. When closed, the door swings into abutting relationship with door jamb 24 and, when door 22 is swung open to the maximum point permitted by the engaged safety latch 10, the relationship is that illustrated in FIG. 3.

The door-mounted structure 12 comprises base 26 which has openings through its bottom plate 28 for the employment of securing screws to secure the base against the door. Base 26 has upturned

side flanges

30 and 32 and upturned rear flange 34, see FIGS. 4 and 5. The top of rear flange 34 is bent forward to form stop 36 which lies in a plane such that the bottom of stop 36 is even with the top of

side flanges

30 and 32.

The forward end of base 26 carries pivoted guide 38. The bottom 40 of pivoted guide 38 has a rolled forward end 42 which is positioned between

side flanges

30 and 32. Pivot pin 44 extends through the side flanges and the rolled forward end 42 to permit pivoted guide 38 to swing with respect to base 26. Upward and

inwardlyturned side flanges

46 and 48 of the pivoted guide are mounted on bottom 40. This defines a channel opening through which a slidable intermediate link can move.

Intermediate link 50 is mounted beneath and between

side flanges

46 and 48 so that it can slide from the retracted position of FIGS. 1, 2 and 4 to the extended position of FIGS. 3 and 5. Downwardly extending stop pin 52 is fixed to and limits the outward sliding 'motion of intermediate link 50 by engaging in slot 54 in 60, which is fixedly attached to engagement link 56, to be manually operable from the outside of the structure 12. Furthermore, the knob 60 has side slots to clear intermediate link 50, and the engagement of knob 60 inn slot 58 provides endwise limits for the sliding motion of engagement link 56 with respect to intermediate link 50. It should be noted that, in the fully retracted,

rightmost position of FIGS. 1 and 4, engagement link 56 extends under stop 36 so that the links and the pivoted guide 38 are prevented from swinging with respect to base 26.

The outer end of engagement link 56 carries an engagement nose 62 thereon which is configured to cooperate with the engagement opening 20 in the rolled end 18 of the latchplate 14. In one arrangement (see FIG. 6), the engagement opening is in the shape of a tee, with the crossbar of the tee running up and down the cylindrical rolled end 18 and lying in a plane substantially through the axis of the rolled end 18 and lying parallel to the face of the closed door. Cooperating therewith, the engagement nose 62 is in the form of a tee having a crossbar which fits through the elongated slot portion of the T-shaped engagement opening 20. The narrow shank of the T-shaped nose 62 fits in the narrower slot of the opening 20, as seen in FIG. 2.

In a presently preferred alternate arrangement, the engagement nose 62 is in the form of a T-shaped slot, as illustrated in FIG. 7. This figure also illustrates the form of the cooperating openings 20 that outline the shape of a tee. As in the first arrangement, once the engagement link 56 rotates about the axis of the rolled end 18 from its initial 90 position, ,it is captured in the engagement opening configuration. Thus, engagement nose 62 can he slid into engagement opening 20 from only the one position. This motion from the position of FIG. 1 to the position of FIG. 2 not only engages the nose in the engagement opening, but also releases the rear end of engagement link 56 from beneath stop 36. Now,

door 22 can be swung open and, at the same time,-

pivoted guide 38 carrying the links swings out away from the base 26 and the links slide with respect to the pivoted guide to the position of FIGS. 3 and 5. Upon reaching the stop position shown in these figures, the door is prevented from further opening motion. Thus, the door is limited in its opening. The configuration of the engagement nose 62 within the engagement opening 20 prevents disengagement thereof in this position, but permits disengagement only in the door-closed position of FIGS. 1 and 2.

As the door is moved from the open position in FIG. 3 to a closed position, link 56 slides into link 50, and link 50 slides with respect to pivoted guide 38. As the dodor closes, these parts close up and, finally, doorclosing motion causes pivoting of the guide 38 and the links carried thereon back into the position wherein they are substantially within the

side flanges

30,32 of the base 26. Now, the structure 12 is returned to the position of FIG. 2. It may be left in that position but, if a full opening of the door is desired, knob 60 is moved to the right to disengage engagement nose 62 from its opening 20 and, at the same time, engagement link 56 locks under stop 36 to retain the structure in the position shown in FIG. 1. Engagement link 56 is provided with a rearward-looking elongated open slot 63 having a width dimension to clear the stop pin 52 and thereby allow the link to slide under the stop 36. Thus, limited opening of the door is accomplished.

From the foregoin it should be evident that there hs been described a safety latch wherein a swingout telescopic structure interengages between the door and the doorframe with positive maximum telescopic limits which limit the extent the door may be opened, and wherein such interengagement may be disengaged only when the door is in its fully closed position.

It should be understood that the materials used in fabricating the invention are not critical and any material generally considered suitable for a particular application may be used. For example, the latchplate, links and base structures may be of such materials as brass, brass-plated steel, aluminum, and possibly even some synthetic materials. Furthermore, any conventional manufacturing process such as casting, machining, stamping, etc., may be used.

It should also be understood that 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 positions of the latchplate and lock structure may be interchanged, and the engagement link may be provided with a bias in its outwardly extended direction by a detent spring fixedly attached to the base and slidably engaging one or both sides of inward extremity of the engagement link. Accordingly, all such modifications and embodiments are deemed to be within the spirit, scope and contemplation of this invention.

This invention having been described in its preferred embodiment, it is clear that it is susceptible to numerous modifications and changes within the scope of the invention and without the exercise of the inventive faculty. Accordingly, the scope of this invention is defined by the scope of the following claims.

I claim:

1. A safety latch for limiting the opening of a door with respect to a doorframe, comprising:

a latchplate for securement to the doorframe, said latchplate having a T-shaped engagement opening therein;

a structure for mounting upon the door, said structure comprising a base with a stop formed therein;

a guide pivotally mounted to said base, said guide having guide flanges;

an engagement link slidably mounted with respect to said guide flanges to slide from a retracted to an extended position, a stop on said engagement link to limit the amount said engagement link can slide out od said guide, said engagement link engaging with respect to said stop to retain said engagement link with respect to said base when said engagement link is in its retracted position, said engagement link also having a manually operable handle thereon, and a T-shaped engagement nose on said engagement link, said engagement nose extending into said engagement opening on said latchplate when the door is closed and said engagement link is extended with respect to said guide, said nose and said opening being configured so that said nose can engage said opening only when said engagement link is lying in said base.

2. The safety latch of claim 1 further including an intermediate link, said intermediate link being slidably mounted in said pivoted guide and said'engagement link being slidably mounted with respect to said intermediate link so that said engagement link can extend beyond said guide.

handle operating through a slot to limit motion of said engagement link.

6. The safety latch of claim 5 wherein said engagement nose is T-shaped and said engagement opening is T-shaped, said nose and said opening being configured so that said nose can engage said opening only when said engagement link is lying in said base.

Claims

1. A safety latch for limiting the opening of a door with respect to a doorframe, comprising: a latchplate for securement to the doorframe, said latchplate having a T-shaped engagement opening therein; a structure for mounting upon the door, said structure comprising a base with a stop formed therein; a guide pivotally mounted to said base, said guide having guide flanges; an engagement link slidably mounted with respect to said guide flanges to slide from a retracted to an extended position, a stop on said engagement link to limit the amount said engagement link can slide out od said guide, said engagement link engaging with respect to said stop to retain said engagement link with respect to said base when said engagement link is in its retracted position, said engagement link also havingn a manually operable hangle thereon, and a T-shaped engagement nose on said engagement link, said engagement nose extending into said engagement opening on said latchplate when the door is closed and said engagement link is extended with respect to said guide, said nose and said opening being configured so that said nose can engage said opening only when said engagement link is lying in said base.

2. The safety latch of claim 1 further including an intermediate link, said intermediate link being slidably mounted in said pivoted guide and said engagement link being slidably mounted with respect to said intermediate link so that said engagement link can extend beyond said guide.

3. The safety latch of claim 2 wherein s stop is formed on said base, said engagement link engagement link with respect to said base when said engagement link is in its retracted position.

4. The safety latch of claim 3 wherein said guide has flanges which guide said engagement link with respect to said guide.

5. The safety latch of claim 4 wherein said engagement link has a manually operable handle thereon, said handle operating through a slot to limit motion of said engagement link.