US3017926A

US3017926A - Bi-fold door assembly

Info

Publication number: US3017926A
Application number: US811071A
Authority: US
Inventors: George R Kauppila
Original assignee: ROBERT L DICKERSON
Current assignee: ROBERT L DICKERSON
Priority date: 1959-05-05
Filing date: 1959-05-05
Publication date: 1962-01-23
Anticipated expiration: 1979-01-23

Description

Jan. 23, 1962 G. R. KAUPPILA BI-FOLD DOOR ASSEMBLY Filed May 5, 1959 Q A a 7/: i m

INVENTOR GEORGE R. KAUPPILA ATTORNEYS The present invention relates to improvements in bi-. fold doors, and more particularly to improved hardware therefor.

In the bi-fold door art the most common hardware for collapsing the door comprises a guide track mounted on the door frame header and a follower mounted on the head rail of the door adjacent its travelling edge. Such a door collapses responsive to a pull adjacent the hinged center thereof and is normally restricted to a 90 degree opening.

The present invention aims to provide effective bi-fold door hardware of more simple and economical construction which does not require the use of a guide track and which will readily swing open 180 degrees.

A further invention is to provide such improved bifold door hardware which will spring-hold the door in both its open and closed positions without the use of auxiliary springs.

Other more particular objects and advantages will, together with these general objects, appear and be understood in the course of the following description and claims, the invention consisting in the novel construction and in the adaptation and combination of parts hereinafter described and claimed.

In the accompanying drawings:

FIG. 1 is a fragmentary horizontal sectional view of a bi-fold door equipped with the present invention and taken at the top of the door.

FIG. 2 is a fragmentary vertical sectional view taken as indicated by the line 2--2 of FIG. 1.

FIG. 3 is a detail elevational view partly in section of one end of the swing arm and with the related bracket shown fragmentarily.

FIG. 4 is a top detail view illustrating the meeting arrangement between a pair of the bi-fold doors and taken similarly to FIG. 1; and

FIG. 5 is a fragmentary vertical sectional view taken as indicated by line 5-5 of FIG. 4.

Referring to the drawings, for purposes of example, I have shown a bi-fold door in mounted by butt hinges 311 on a side jamb'll3 of a doorway and having its inner and outer sections flitta-ltlb hinged together by butt hinges 12 to collapse or fold forwardly. For a reason other than forward collapsing, to be later detailed, the knuckles or barrels 12a of hinges 12 are purposely set back from the rear face of the door. The barrels liia of hinges 11, on the other hand, are set forwardly to permit an 80 degree swing of the inner door section.

Folding of the door is controlled by a swing arm 14 which is bent at an elbow l5 defining humerus and forearm portions 16li7. The swing arm is fabricated from steel rod stock or some other suitable material which will provide adequate spring flexure at the elbow. As shown for the outer end of the arm 114 in FIG. 3, both ends thereof are bunched from a round to a square crosssection and kerfed endwise to form forks 13 at the free ends of the humerus l6 and forearm 17. These forks are suitably bored and tapped to have their gaps bridged by the enlarged shank portions 21 of respective necked pivot pins 19-20 each having a threaded neck 22 and a slotted head 23. The pins -192t are used to pivotally mount the forked terminal ends of the humerus and f0re arm on the flanges of Z and angle bracket 24-25, respectively, the Z bracket being suspended from the head at fire saunas Patented Jan. 23, 1962 jamb 26 and the angle bracket being mounted on the back of the outer door section 10b adjacent its head.

The spring-holding affects, at both the open and closed positions of the door, the included angle at the elbow between the humerus and the forearm is increased by elbow flexure at said positions over the corresponding angle when the swing arm is in a relaxed condition. Freedom from spring loading is achieved through a large part of the door travel by making the lineal distance between the axes of the pivots race, when the swing arm is relaxed, substantially equal to the lineal distance between the swing axes of the hinges 11li2. In this manner a parallel action results between the swing axes of the door sections and the pivotal axes at the ends of the swing arm during swing travel of the door sections between the initial point of contact at the free edge of the outer section Citib with the head jamb (position #2 in FIG. 1) and the point of contact of the forearm portion 17 with the inner door section 10a (position #4). In most installations it is found desirable to have position #2 occur fairly close to the fully closed position #1, and such can be readily adjusted by shifting the brackets 24-25 relative to the hinges 11-12.

With the swing arm partaking of relaxed parallel action between positions #2 and #4, as illustrated by position #3, it can be seen that if the door is closed further than position #2, the parallel action ceases because the free side edge of the outer door section 19b must thereafter slide along the head jamb stop 27 rather than continuing to swing. Thus further closing of the door can only continue by gradual increase of the lineal distance between the pins 1920. This increase is achieved by spring flexure of the swing arm at its elbow 15. It is important, as before mentioned, to note that by the time the door reaches its fully closed position the axis of hinges 12 has moved slightly behind a straight line drawn between the pivotal axes at the ends of the swing arm. By this arrangement the swing arm in attempting to relax from its flexed or tensioned condition keeps the door sprung closed since its tendency has become one of urging the door sections to fold or collapse rearwardly rather than forwardly.

Returning to position #4 and namely that corresponding to the first point of contact between the forearm 17 and the inner door section 10a, it can readily be seen that further swinging of the door toward the wall adjoining the doorway can only be accomplished by again spring flexing the elbow 15 to increase the included angle and thereby increase the straight line distance between the pins l9-2tl. Of importance to note is the fact that when the door has swung far enough toward fully open position #4 to bring a line drawn between pins 19-26 behind the swing axis of hinges 11, maximum flexure of the swing arm has been reached, and hence the door will thereupon be spring urged toward position #4. Thus it is seen that the door is spring-held in both its open and closed positions by flexure of the swing arm.

From an inspection of position #5 it can be seen that the humerus portion 16 of the swing arm must be made long enough to permit the forearm 17 to swing into substantially parallel relation to the wall while taking into account the thickness of the door sections and the offset of the barrels of the hinges llll. At the same time the brackets 24-45 must be located far enough from the hinges 11-12 to make the distance from the pin 2% to the free edge ofthe outer door section litb less than the length of the forearm 17. In this regard, it can be seen that the further the pin 19 is displaced laterally of the doorway from the adjacent side jamb, the greater can be the included angle at the elbow 15. Increase of this angle may be important in some installations to keep the rearward displacement of the elbow 15 to a minimum at the fully closed position of the door. For example, in FIGURES 1-2 I have shown an arrangement wherein the stop 27 of the head jamb is a separate piece having its upper face rabbeted to provide a chamber 23 for housing the swing arm when the door is closed.

To pull the door open there is provided a handle 29 which is preferably located on the front face of th outer door section b between its hinged edge and a vertical cross-sectional plane through the pivot pin 23. Pull on a handle so located tends to immediately collapse the door forwardly and leaves the handle exposed when the door is in its fully open position.

If the door is located in a passageway as distinguished from a closet opening, provision is made to resist pushing action by a person applied adjacent the free edge of the outer door section 10b since such would have the undesirable tendency to urge the door to collapse rear- Wardly rather than forwardly. This resistance is accomplished by mounting a male fitting 31 on the swing jamb 30 forwardly of its stop and boring a mating hole 32 in the corresponding stile of the outer door section 1012 at the same height from the floor. The hole 32. must be slightly larger in diameter, particularly at the mouth, than the fitting 31 toallow for the pivoting of the free side edge of the door as it slides at the top along the stop of the head jamb from position #2 to the fully closed position. At the latter, the fitting 31 by being lodged in the hole 32 will resist forward pushing of the door if applied toward the swing jamb 30 from the pivotal axis of the pin 20. A handle may be placed on the back side of the door opposite the handle 28 if desired to indicate the proper push point. Such a handle should not project rearwardly farther than twice the offset of the swing axis of the hinges 11 so as not to interfere with complete opening of the door.

In extra wide openings it may be desired to mount a pair of bi-fold doors 10A10B meeting in the center. To resist one of such a pair from being pulled forwardly by a grip on its free edge when the other door is open, and to resist forward pushing from the back side near the center of the opening, the hole 32 of each door is placed close to its upper end and in alinement with that of the other. As shown in FIGURES 45, the members 31a for these holes are secured at opposite sides of a thin two-ply mounting plate 33 which projects forwardly between the meeting edges of the doors from the head jamb stop, denoted 34, and has a looped root end portion 33a. The latter can be mortised into the stop and the mortise filled by filler 35.

Thus it is seen that I have provided a versatile bi-fold door assembly of simple and economical construction in which a swing arm functions not only to collapse the door, but also to spring-hold the door in both its open and closed positions.

The advantages of the invention, it is thought, will have been clearly understood from the foregoing detailed description of the illustrated preferred embodiment. Minor changes will suggest themselves and may be resorted to without departing from the spirit of the invention, wherefore it is my intention that no limitations be implied and that the hereto annexed claims be given a scope fully commensurate with the broadest interpretation to which the employed language admits.

What I claim is:

1. A bi-fold door assembly comprising, a door frame, inner and outer bi-fold door sections hingedly connected together to collapse in a forward direction, said inner section being hingedly connected to a side jamb of said door frame for forward swinging movement between open and closed positions, and a bent one-piece swing arm adapted to flex and pivotally mounted at its ends to the back of said outer section and to said door frame for swinging movement, said end pivots of the swing arm being spaced apart when said door is in its said closed position a distance greater than when said door is partly open.

2. The structure of claim 1 in which the hinge axis between said door sections is located rearwardly of a line connecting said end pivots of the swing arm when said door is in said closed position.

3. A bifold door assembly comprising, a door frame,

inner and outer bi-fold door sections hingedly connectedtogether to collapse in a forward direction, said inner section being hingedly connected to a slide jamb of said door frame for forward swinging movement between open and closed positions, and a bent one-piece swing arm adapted to flex and pivotally mounted at its ends to the back of said outer section and to said door frame for swinging movement, said end pivots of the swing arm being spaced apart when said door is in its said open position a distance greater than when said door is only partly open.

4. The structure of claim 2 in which the hinge axis between said inner section and said side arm is located forwardly of a line connecting said end pivots of the swing arm when said door is in said open position.

5. A bi-fold door assembly comprising, a door frame, inner and outer -bi-fold door sections hingedly connected together to collapse in a forward direction, said inner section being hingedly connected to a side jamb of said door frame for forward swinging movement between open and closed positions, and a bent one-piece swing arm adapted to flex and pivotally mounted at its ends to the back of said outer section and to said door frame for swinging movement, said end pivots of the swing arm being spaced apart when said door is in its said closed and open positions respective distances each of which is greater than when said door is intermediate said positions.

6. The structure of claim 5 in which the hinge axis between said door sections is located rearwardly of a line connecting said end pivots of the swing arm when said door is in said closed position, and in which the hinge axis between said inner section and said side jamb is located forwardly of a line connecting said end pivots of the swing arm when said door is in said open position.

References fitted in the file of this patent UNITED STATES PATENTS 563,058 Peck June 30, 1896 1,000,707 Borg Aug. 15, 1911 2,014,591 Sanders Sept. 17, 1935 2,725,099 Frie et a1. Nov. 29, 1955 2,763,900 McAfee et al. Sept. 25, 1956