Friction Door Holder

Abstract

A friction door holder having a door frame mounting bracket and a door supported channel formed with an elongated guide slot. The channel houses a self-lubricating friction assembly. A drive arm pivoted to the mounting bracket moves the friction assembly within the channel. The friction assembly comprises a slide block which has a generally U-shaped elongated body formed with generally parallel elongated depending sides positioned closely adjacent the sides of the channel and joined together by a base section located adjacent the guide slot. The slide block body includes firstly an elongated guide head projecting from the base and sandwiched between the edges of the guide slot, and secondly a plurality of projecting retainer legs depending from the corner extremities of the depending sides towards the channel bottom. A metal plate carrying a friction liner is housed within the slide block and is retained between the slide block legs; and an elongated cam spring is housed within the slide block with one end fixed to the slide block and the other end being free to move relative the slide block. An adjustment screw carried by the slide block contacts adjustably the free end of the cam spring to vary the degree of friction engagement between the friction liner and the channel. The slide block is preferably fabricated of a solid plastic, such as nylon, containing a homogeneously dispersed solid lubricant, such as molybdenum disulfide.

Description

BACKGROUND OF THE INVENTION

Friction door holders are well known in the art. These devices serve to hold a door at a desired open position with a minimum of manual effort to attain the hold position. Additionally, the holding function must be manually overcome readily in order to close the door.

The repetitive opening and closing of a door employing a friction holder subjects the holder components to considerable wearing forces and in extreme cases to destructive shock.

Excessive component wear ultimately introduces looseness or play in the holding function which is detrimental to good operation. Additionally, this condition contributes to the premature deterioration of the holder and to user dissatisfaction.

Accordingly, there is a substantial demand for door holders capable of withstanding reliably the door cycling generated by heavy traffic which requires repetitive opening and closing and also intermediate holding functions.

DETAILED DESCRIPTION OF THE PRIOR ART

The prior art is fairly prolific in friction door holders. Most of these devices are complicated structurally and do not withstand the severe conditions generated by heavy traffic.

In many instances, the holders are noisy and erratic in operation, require constant maintenance including lubrication, and wear out prematurely, initially developing door play and ultimately complete failure in the door holding function.

Examples of prior art friction door holds are shown in U.S. Pat. No. 330,138, No. 406,840, No. 1,330,333 and No. 2,289,092.

SUMMARY OF THE INVENTION

The present invention is primarily directed to improvements in the friction assembly which characterizes friction door holders. This assembly must serve two functions which at the outset appear conflicting. Friction must be attained to provide the holding function, but at the same time the door must be readily movable to a desired position without excessive manual exertion. Additionally, the friction and also the moving functions must not produce an excessive wear of components.

The improved friction assembly of this invention is characterized by a plastic slide block that glides quietly and smoothly, withstands tremendous shock, and has inherent lubricity which makes lubrication unnecessary. This block features wall and guide surfaces that fit closely within a channel. The close fit attained between the slide block and the channel prevents excessive play which would otherwise lead to loose holding of the door. However, because of the self-lubricating function of the slide block, undesired wear and friction are not created. Thus, life expectancy of the holder is greatly extended.

Additionally, the slide block is simply constructed so that it may retain and slide reliably the actual friction element which may be individually adjusted for proper operation without the customary allowance for periodic service wear in the slide block.

DETAILED DESCRIPTION OF THE DRAWINGS

In order that all of the structural features for attaining the objects of this invention may be readily understood, reference is herein made to the accompanying drawings, wherein:

FIG. 1 is a simplified perspective view showing the door holder of this invention surface mounted on a flush door;

FIG. 2 is a section view taken along line 2--2 of FIG. 1 showing the surface mounted channel and its friction assembly, the drive arm, and the frame bracket;

FIG. 3 is a simplified perspective view showing the door holder modified for concealed mounting on a flush door;

FIG. 4 is a section view taken along line 4--4 of FIG. 3 showing the concealed mounted channel and its friction assembly, the drive arm, and the frame bracket;

FIG. 5 is a perspective view of the concealed door holder of FIG. 3 with portions of the channel broken away to show the general details of the friction assembly and the stop shock assembly;

FIG. 6 is a section view taken along the line 6--6 of FIG. 5 showing details of the friction assembly when in friction holding contact with the channels;

FIG. 7 is an exploded view of the friction assembly;

FIG. 8 is a section view taken along the line 8--8 of FIG. 5 showing details of the friction assembly when in friction holding contact with the channel;

FIG. 9 is a view of the stop shock assembly with the end block shown in section; and

FIG. 10 is a perspective view showing conventional modifications in the channel for surface mounting.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIGS. 1 and 2, door holder 11 of this invention is shown surface mounted to flush door 12. The principal parts of door holder 11 comprise frame bracket 13, friction assembly drive arm 14, channel 15, friction assembly 16 (FIG. 2), and shock assembly 17 (FIG. 9). Frame bracket 13 is applied to door stop 18 in the particular embodiment shown in FIGS. 1 and 2.

It is the purpose and function of the door holder to enable door 12 to be held open at any position from slightly open to approximately 110.degree.. This function is attained generally by friction assembly 16 (see FIG. 8) applying a holding friction force to channel 15 (or channel 23 in FIG. 3), as is hereafter explained in detail. This friction force is, of course, overcome by the manual application of a door opening or closing force to door 12 so that the door may be placed at a desired position relative frame 19. Stop shock assembly 17 (FIG. 9) serves as a shock absorber for minimizing a racking force in the event door 12 is subjected to an excessive door opening force.

FIGS. 3 and 4 show the basic door holder of FIGS. 1 and 2 modified in a conventional manner so that this door holder may be applied in a concealed manner to the top edge of door 12. In this embodiment, the concealed holder 20 comprises frame bracket 21, friction assembly drive arm 22 and channel 23, all of which correspond to components 13, 14 and 15, previously described with reference to FIGS. 1 and 2.

The major difference in the door holder embodiment of FIGS. 1 and 2 as compared with that of FIGS. 3 and 4 is that horizontal mounting holes 24 and 25 are provided for channel 15 of FIG. 1 through which a plurality of screws 26 (FIG. 2) fix the channel to door 12. In the channel of FIG. 3, however, vertical mounting holes 27 and 28 are provided so that a plurality of screws 29 (FIG. 4) may fix the channel to door 12.

Channel 23 houses friction assembly 16 and stop shock assembly 17, which are basically identical in construction with those of the door holder embodiment of FIGS. 1 and 2.

For illustrative purposes, FIGS. 5 through 8 show the details of the improved friction assembly 16 which characterize this invention in association with the concealed door holder 20 shown in FIGS. 3 and 4. It should be understood that with the exception of the mounting holes, the door holder embodiment of FIGS. 1 and 2 and that of FIGS. 3 and 4 are essentially the same.

Referring now to FIGS. 5 through 8, door holder 20 comprises a channel 23 which may be preferably fabricated of stainless steel, steel or bronze. Galvanic corrosion is eliminated by the use of a plastic slide block as hereafter described. Channel 23 may be generally square or rectangular in construction and this channel includes vertical side walls 30 and 31 joined together by bottom 32 and including also a top 33 which is formed with an elongated guide slot 34. Friction assembly 16 is housed within channel 23. Additionally, stop shock assembly 17 is also housed within channel 23.

The left end of channel 23, as viewed in FIG. 5, receives plastic block 35 which is formed with hole 28 through which mounting screw 29 passes as is shown in FIG. 4.

The right end of channel 23, as viewed in FIG. 5, receives plastic block 36 which is formed with hole 27 which likewise receives a screw, such as 29, for mounting the channel.

Friction assembly 16 reciprocates within the track provided by the hollow channel 23. Its left most movement is limited by block 35, and its right most movement is limited by stop shock assembly 17 which will be hereinafter explained with reference to FIG. 9.

Friction assembly 16 comprises a slide block 40 which has a generally U-shaped elongated body formed with generally parallel elongated depending sides 41 and 42. Depending sides 41 and 42 are joined together by a base section 43. The ends of depending side 41 carry retainer legs 44 and 45 and the ends of depending side 41 carry retainer legs 46 and 47. Depending sides 41 and 42 are parallel and are in friction sliding contact with the adjacent channel walls 30 and 31. Base 43 carries elongated guide head 48 which is sandwiched relatively tightly within guide slot 34.

Slide block 40 is preferably fabricated of a solid plastic containing a homogeneously dispersed solid lubricant. A preferred material for this requirement is nylon containing molybdenum disulfide. A plastic component of nylon having controlled amounts of molybdenum disulfide homogeneously dispersed therein is capable of producing a minimum wear in a component subjected to extensive cycling. Additionally, in view of the fact that in a door holder of the design described, slide block 40 must be in close contact with the channel 23 in order to minimize objectionable looseness or play in the parts, the introduction of a solid lubricant in slide block 40, such as molybdenum disulfide, minimizes undesired friction which will detrimentally effect the operation of the device.

For further information concerning a preferred plastic containing a solid lubricant, reference is herein made to the article, "Molding Resins," published by the Polymer Corporation of Reading, Pennsylvania, and also the article, "Molybdenum Disulfide in Nylon for Wear Resistance," authored by Thomas E. Power and published in the June 1960 issue of Modern Plastics.

Metal cam spring 50 is located between the depending legs 41 and 42 of slide block 40.

In particular, rivets 51 and 52 fix the right end of cam spring 50 to base 43 and head 48 of the slide block. The left end of cam spring 50 is moved relative slide block 40 by means of friction adjustment screw 53 housed within a stepped hole formed in base 43 and head 48 of the slide block 40. Screw 53 is formed with a circular flange 54 which retains the screw within the slide block. Screw nut 55 is received by the threaded portion of screw 53 so that selective rotation of the screw may drive the nut upwardly or downwardly.

Cam spring 50 is formed with a generally V crimp 56 which serves as a cam. The apex of cam 56 rests against metal plate 57 to which is bonded asbestos friction liner 58. Manual adjustment of friction screw 53 moves nut 55 so as to increase or decrease a downwardly directed force against the left end of cam spring 50 so that cam 56 may exert a greater or lesser pressure against friction subcombination 57, 58.

Accordingly, the degree of holding friction generated by the friction assembly 16 and channel 28 may be manually adjusted by screw 53 to produce a desired holding force which at the same time will, nonetheless, enable door 12 to be moved to a desired position with a non-objectionable manual force.

In view of the particular construction of slide block 40 which enables tight slidable engagement between the slide block and channel 23, channel 23 is coupled to the drive arm 22 without a looseness or play between components which characterized prior art door holders of the general type described herein. This looseness, of course, is a problem which is generally inherent in a door holder of the type described, because drive arm 22 must not only pivot relative slide block 40 but also must reciprocate the slide block within channel 23.

Drive arm 22 is coupled to slide block 40 by pivot pin 60 which passes through a hole 61 formed in drive arm 22, and a hole 62 formed in head 48 and base 43 of slide block 40. Washer 63 is sandwiched between drive arm 22 and head 48 so as to facilitate relative rotation between drive arm 22 and slide block 40. Pivot 64 couples frame bracket 21 to the far end of drive arm 22. Bracket 21 is formed with a plurality of mounting holes 65 by which the bracket is fixed to a door frame or other support structure, as may be required.

FIG. 9 shows stop shock assembly 17. Shock assembly 17 serves the purpose of absorbing an excessive door opening force which might produce door racking. The shock assembly includes block 36 which carries circular male tip 66. Helical shock absorber spring 67 is supported upon tip 66 so that the spring is disposed in the path of slide block 40 when the door is opened to its extreme angular limit. The spring absorbs the excess energy applied to the door and minimizes undesired destructive forces.

FIG. 10 shows the far end fragment of surface mounted channel 15. In particular, far end block 68 is formed with a horizontal hole 69. When block 68 is inserted within channel 15, holes 25 and 69 are in alignment. The near end of channel 15 containing the stop shock assembly (not shown) is correspondingly modified. These minor changes in surface channel 15 as compared to concealed channel 23 require no structural change in friction assembly 16. The only modifications required are in the holes formed in the plastic end blocks, in that the mounting holes in channel 15 must be horizontal rather than vertical.

It should be understood that the structure herein described is merely illustrative of the principles of this invention, and that modifications may be made without departing from the scope of the appended claims.

Claims

What is claimed is:

1. In a friction door holder having a door frame mounting bracket, a door supported elongated, hollow channel formed with a pair of side walls, a bottom and a top having an elongated guide slot, with the channel housing a friction assembly, and a friction assembly drive arm coupling the mounting bracket and friction assembly to move the friction assembly relative the channel, the improved friction assembly comprising a slide block slidably movable within the channel, the slide block having an elongated body formed with generally parallel elongated depending sides positioned closely adjacent the sides of the channel and joined together by a base section located adjacent the slot, with the body including an elongated guide head projecting from the base and sandwiched between the edges of the guide slot, the drive arm being pivotally coupled to a mid portion of the guide head, a support carrying a friction liner housed within the slide block, a cam element housed within the slide block with the cam element being adjustably supported by the elongated guide head and the base section, an adjustment screw carried by the guide head and the base section of the slide block to move adjustably the cam to vary the degree of friction engagement between the friction liner and the channel bottom, and a plurality of retainer legs projecting from the corner extremities of the slide block depending sides toward the channel bottom, the retainer legs serving as guide and limit stops for the support and friction liner.

2. The combination of claim 1 in which the friction liner projects downwardly beyond the retainer legs to establish friction contact with the channel bottom with the retainer legs being the only portions of the slide block contacting the friction liner.

3. The combination of claim 2 in which the cam is part of an elongated spring fixed at one end to the base and guide head of the slide block and the other end being free to move relative the slide block in response to manual variations in the screw adjustment.

4. The combination of claim 3 in which the cam is a generally V-shaped crimp located substantially in the central portion of the elongated spring to apply a single substantially centrally located force on the friction liner.

5. In a friction door holder having a door frame mounting bracket, a door supported elongated, hollow channel formed with a pair of side walls, a bottom and a top having an elongated guide slot, with the channel housing a friction assembly, and a friction assembly drive arm coupling the mounting bracket and friction assembly to move the friction assembly relative the channel, the improved friction assembly comprising a slide block slidably movable within the channel, the slide block having a generally U-shaped elongated body formed with generally parallel elongated depending sides positioned closely adjacent the sides of the channel and joined together by a base section located adjacent the slot, with the body including firstly an elongated guide head projecting from the base and sandwiched between the edges of the guide slot and secondly a plurality of projecting retainer legs projecting from the corner extremities of the depending sides toward the channel bottom, a metal plate carrying a friction liner housed within the slide block between the slide block legs to be retained and guided thereby, an elongated cam spring housed within the slide block with one end fixed to the slide block and the other end being free to move relative the slide block, and an adjustment screw carried by the slide block to contact adjustably the free end of the cam spring to vary the degree of friction engagement between the friction liner and the channel.

6. The combination of claim 5 in which the slide block is fabricated of a solid plastic containing a homogeneously dispersed solid lubricant.

7. The combination of claim 6 in which the plastic is nylon and the solid lubricant is molybdenum disulfide.