US 3306643 A
Description (OCR text may contain errors)
Feb. 2S? 96? C, W` REED. 393643 DOORKNOB COVER Filed June 18, 1964 2 Sheets-Sheet 2.
rroR/vfx United States Patent O 3,306,643 DOORKNIB COVER Clifton W. Reed, 5016 Calvin Ave., Tarzana, Calif. 91356 Filed `lune 18, 1964, Ser. No. 376,013 4 Claims. (Cl. 292-1) The present invention is related generally to doors and latches for doors; but it is more particularly concerned with a protective device that can be applied to the operating doorknob or handle of an ordinary door latch to prevent a young child from turning the doorknob and opening the door.
Many parents have experienced the need for locking a door to prevent a young child from opening it. During the early years of childhood, a childs curiosity leads him to explore while has has not yet acquired suicient experience and good judgement to recognize dangers that he may encounter in strange territory. Even if told to stay in a house or in a room, a child is not lalways obedient and often yields to the temptation to see what is on the other side of the door. A typical need is to render secure the front door of a home so 'that the child may be allowed to play in the house without the need of continual observation so that the parent is not required to be continually on the alert. The front door of the home is la particular problem since if the `child is able to open the door while unobserved, he is likely to get into such hazardous areas yas the street, or is able to run away or get into other mischief.
A common and familiar precaution involves equipping doors with some positive locking means, for example, a chain latch or a dead bolt of some type which cannot be manipulated lby the child as a preliminary to opening the door. Devices of this type require special installation, which is not always easily and quickly accomplished,
.and which may also involve a not inconsiderable expense if .someone in the family is not able to do this work.
Perhaps a more important objection to locking devices of this type is that they deny normal usage of the doors to adults. Again returning to the example of a front door of a home, such known types of locking devices are placed on the inside and can be operated only from that side. Consequently they cannot be restored to locking position by someone who has passed through the door going out of the house, and they are effective when locked to prevent anyone from entering the house since they can be manipulated or released only from the inside. For these reasons, such locking devices as dead bolts and .chains are frequently not installed because of the inconvenience they produce; and even if installed, are often not used for the same reason.
Hence it becomes a general object of the present invention to provide a simple and economical device lwhich can render a common door lock secure against the lattempts of a young child to open the door.
Another object of the invention is to provide Ia security device for a common door lock which can be manipulated by adults, and thus preserve all the normal uses or characteristics of the door, but which cannot be manipulated by a young child in a manner to render the door insecure against him.
A further object of the present invention is to provide a device of this character which requires no modification of the doorknob and which is easily installed and removed, preferably requiring no permanent installation that involves nails, screws or the like that leave holes or scars on the woodwork after removal.
These objects are achieved according to the present invention by providing, for a rotatable doorknob operating a latch, a doorknob cover comprising a hollow body havlCe ing an annular Wall and on opening to admit the doorknob inside the body, and retaining means expandable t0 pass over the doorknob and normally contracted to a position engageable with the doorknob to resist removal of the cover from the doorknob. The body has a smooth interior bearing surface causing the b-ody to turn freely on the doorknob and preventing transmission to the doorknob Iof sufiicient torque to operate the doorknob normally, thus requiring removal or deformation of the cover to permit turning the doorknob. In a preferred embodiment, the body wall and the retaining means are elastic and integral with each other, since the entire doorknob cover is molded from a material having a smooth surface with a 4low coefficient of friction so that the cover turns easily in contact with the doorknob but can be easily placed on or taken off the doorknob by relative movement in an axial direction of the doorknob.
When a cover of this character is provided, it may be placed upon the familiar rotationally mounted doorknob by moving the cover forwardly in an axial direction of the doorknob over the doorknob. The body is of suicient stiffness that it maintains substantially its original size and shape and cannot be compressed by the application of manual pressure to exert enough torque on the doorknob to operate the doorknob and release the door latch. The typical doorknob has a section of maximum diameter with a section Iof reduced diameter spaced inwardly therefrom, thus providing shoulder `means against which the elastic retaining means of the doorknob cover can be engaged to prevent the removal of the cover except by an adult or an older child.
How the above objects and advantages of the present invention, as well as others not specifically referred to herein, are attained will be more readily understood by reference to the following description and to the annexed drawings, in which:
FIG. 1 is a side elevation of a doorknob of familiar design and a cover therefor, with the cover adjacent the doorknob in the position occupied immediately prior to installation of the cover on the doorknob;
FIG. 2 is an enlarged vertical longitudinal section through the cover with the cover in place on the doorknob;
FIG. 3 is a Vertical transverse section through the cover on line 3 3 of FIG. 2;
FIG. 4 is a longitudinal section through a cover constituting a variational form of the invention;
FIG. 5 is a view similar to FIG. 4 illustrating how the cover may be deformed to permit operating the doorknob 'without removal of the cover;
FIG. 6 is a combined side e-levation and longitudinal section of the -door-knob cover of FIG. 2 illustrating the combination therewith of locking means preventing removal of the cover;
FIG. 7 is a vertical transverse section on line 7-7 of FIG. 6;
FIG. 8 is a longitudinal section through a doorknob cover illustrating a further modification of the present invention;
FIG. 9 is an end-elevation of the cover of FIG. 8 taken on line 9 9 thereof;
FIG. 10 is a combined elevation and section of a cover as in FIG. 2 showing a modification thereof;
FIG. 1l is a side elevation of a twoapiece construction of a cover embodying the present invention;
FIG. 12 is a longitudinal section through the cover of another form of the invention showing in elevation an adapter for a non-circular doorknob;
FIG. 13 is a longitudinal section through the cover and adapter of FIG. 12; and
FIG. 14 is a transverse section on line 14-14 of FIG. l2.
Referring now to FIGS. 1 and 2 of the drawings, there is illustrated therein a doorknob which is rotatably mounted on idoor 11 to retract spring latch 12 which normally engages a latch plate in the stationary door jamb (not shown). When retracted, latch 12 disengages the latch plate and allows the door to open, as will tbe understood without illustration. The operative connection between doorknob 10 and latch 12 may be of any suitable type and does not constitute any part of the present invention.
The shape or profile of the doorknob 10 is one which is currently favored and is very commonly encountered. It illustrates certain general characteristics of a doorknob, but beyond that the precise shape or outline of the doorknob is not limitative upon the present invention. However, it will tbe noticed that doorknob 10 has a zone 14 of maximum diameter and inwardly therefrom, that is, in a direction toward door 11, the doorknob has another zone 15 of reduced diameter. The exterior surface 16 of the doorknob is ordinarily a sur- -face of revolution so that at any point the intersection of surface 16 with a transverse plane normal to axis 17 is a circle.
Indicated generally at 20 is a cover of one-piece design which is adapted to .be placed over the doorknob to provide the desired security against manipulation of the doorknob by a young child. Cover 20 comprises a body portion 21 which is open at one side to admit doorknob 10 into the cover. -Body 21 comprises a generally annular wall 22 and an integral end wall 23 closing the body o-n the side opposite the opening for the doorknob.
Around the opening for the doorknob, the cover is provided with elastic retaining means 28 which, in the embodiment of FIG. l, consists of a series of elastic segments or fingers 24 separated from one another by slots 25. These segments 24 are integral with the body wall 22. Slots 25 are of a size and shape to provide a desired degree of expandability to the passage `between segments 24 since slots 25 permit the segments to spread apart and pass over doorknob 10 as the cover is moved in the direction of arrow 26 from the position of FIG. 1 to the position of FIG. 2. Once past the zone of maximum diameter and advanced to zone 15 of reduced diameter, the segments 24 can contract to their original position and by engagement with the doorknob resist removal of the cover by reverse movement relative to the doorknob in an axial direction. For this reason, segments 24 when in the nor-mal contracted position define an opening between them which is of lesser diameter than the interior diameter of ibody 21. Although the exact shape of these segments is not critical, it is preferred that they have a sharply indente-d portion 27 from which they flare out at the ends of the segments to a size large enough to receive the maximum diameter of the doorkno'b. This permits the doorknob as it passes axially inwardly along the segments to cam the segments radially outwardly and expand them as they pass over the doorknob.
Cover 20 is -designed to turn relative to the doorknob, when it is in place on the doorknob. This makes it difficult, or preferably even impossible, to transmit sufficient torq-ue to the doorknob to turn it and operate latch 12 in opposition to the spring normally urging latch 12 outwardly. For this reason, the interior surface of wall 22 is made as smooth as possible and is also a surface of revolution of slightly larger diameter than the maximum diameter at section 14 of the doorknob. Thus the cover is normally more or less annularly spaced from the doorknob.
The cover is made of material such that body 21 has sufficient stiffness to retain substantially its original size and shape under the external pressure applied by the hand of a person attempting to open the door. This characteristic can be regulated so that even a stron-g adult cannot compress the cover sufficiently to turn the doorknob, much less a young child. The rigidity of the annular wall is .derived at least in part from the presence of wall 23 which aids the annular body wall to maintain its shape and resist compression.
In a preferred embodiment, the doorknob cover is made in a single piece and is molded yfrom a material having a low coefficient of friction. For this purpose, the synthetic resins or plastics are very satisfactory, and polyethylene is particularly so because it has a waxy surface with a particularly low coefficient of friction. A plastic of this nature is sof-ter than the metal of the doorknob so that it does not scar or scratch the doorknob, turns freely on it, and gives to the segments 24 the desired degree of elasticity.
In defining the body as stiff, it is meant that the body is not easily bent or deformed; but the degree of stiffness is not necessarily such that the lbody is completely rigid or inflexible. At the other extreme, a limpl or shapeless material adapts itself to the shape of the doorknob under external pressure and the resultant large area of contact makes it possible with most materials to turn the doorknob by applying only hand pressure from the outside. An ideal material havin-g substantially zero coefficient of -friction would not transmit an operative amount of torque to the doorknob, even if limp or collapsible; but with materials so far considered practical the possible contact area is reduced by making the :body with some degree of stiffness. The stiffness of the wall 22 is preferably such that it makes possible only a limited total area of contact :between the doorknob cover and the doorknob itself, at most; and this characteristic, combined with the low coefficient of friction existing #between the two, makes the doorknob secure against operation by grasping the cover.
When an adult desires to open the door, the cover is simply pulled off of the doorknob and the doorknob operated in the usual manner. After this, the cover is replaced on the doorknob, restoring the door to a secure condition. It is obvious that the door can be operated from the outside in the usual manner and after a person goes through the door, the desired degree of security can be maintained by him after the door is closed by simply replacing the cover before closing the door.
Under some circumstances, it may be desired to make removal of the cover considerably more difficult. For this purpose, there may be added a comparatively non-yielding locking member, as shown in FIGS. 6 and 7. While this member may be a string or any other non-extensible member wrapped around the doorknob to hold the segments 24 from expanding, in a simple form the locking member 29 is simply a metal spring wire with its two ends overlapping. With the locking member 29 in place, the elastic retaining means provided by segments 24 is held against expanding to a diameter permitting the cover to be removed from the doorknob. The ends of locking member 29 can be grasped and spread apart to enlarge the spring and to permit removal of the locking member, after which the doorknob cover can be removed in the manner previously described.
There is shown in FIGS. 4 and 5 a variational form of the invention in which the cover 30 is made in two pieces. One of these pieces is an inner, cup-shaped member 32 which provides the desired physical characteristics for the body portion of the cover. The outer shell 34 surrounds or encloses the inner member 32 and projects beyond the cup-shaped member at the open side thereof in order to provide elastic retaining means 35 of reduced inside diameter holding the cover on the doorknob.
In this embodiment of the invention, it is contemplated that the inner mem-ber 32 can be made of a comparatively stiffer or rigid plastic, or even metal if desired. On the other hand, the outer shell 34 is made of a much more elastic and easily deformable material. The outer member may also be cup-shaped with the inner member acting as a liner therein. The portion 35 of the outer shell extending beyond the inner member 32 is suiciently elastic and stretchable that it can expand to go over the doorknob without requiring segmentation as is provided by slits 25. For this purpose, it is contemplated that the outer member may be made of a relatively soft, pliable material, such as rubber, which is much more easily stretched than the polyethylene of the first embodiment described. Also, the ru-bber may have the characteristic of a higher coecient of friction thanspolyethylene or other plastics.
Advantage can be taken of these characteristics to design the outer shell in such a way that by compressing the elastic retaining portion 35 between the thumb and fo-refinger as shown at 36 in FIG. 5, portions of the neck of the shell can be brought into engagement with the doorknob and, because of the sufficiently high coeicient of friction of the material of the shell, the doorknob can be turned by an adult without removing the cover from the doorknob. It would normally be impossible for a young child to operate the doorknob in this manner because his hands are not large enough to span the doorknob and not strong enough to compress the shell in the manner shown; but it is possible for an adult to do this.
Another possible modification of the invention is shown in FIGS. 8 and 9 in which that portion of the cover 40 providing the elastic retaining means 41 includes 4an inwardly turned, segmented flange 43, the segments being formed between successive short slots 44. In this embodiment of the cover, the ends of the segments or fingers 43 normally engage the doorknob as shown in FIG. 8 to yieldingly resist removal of the cover from the doorknob by a pull axially of the doorknob. Because of the yielding nature of the material, the fingers bend at their bases to extend outwardly of the shell when a sufficient pull to the left in FIG. 8 is applied and allow the cover to pass over the doorknob for removal. Conversely, when the cover is applied to the doorknob in the first instance, the segments 43 bend into the shell at their bases and spread apart to pass over the doorknob 10.
The doorknob cover illustrated in FIGS. 1 and 2 is described as being made from a material having a low coeicient of friction so that even though limited areas of the cover are brought into contact with the doorknob, sufficient torque to operate the doorknob cannot be transmitted to the doorknob. On the other hand, the embodiment illustrated in FIGS. 4 and 5 is made from a material having a relatively high coeicient of friction. This suggests a possible combination of these two types of materials, one example of which is shown in FIG. l0. In this latter embodiment, cover 20 is made principally from a material having a low coefficient of friction, and thus is similar to the form illustrated in FIGS. 1 and 2. It differs therefrom by the addition to it of pads 45 located on the inside surfaces of the segments 24. These pads may be made of rubber or other material having a high coefficient of friction and provide on the interior surface of the cover localized areas having this characteristic. Pads 45 are normally held out of contact with doorknob 10; but, because of its deformability, the cover can be compressed manually sufficiently to bring these pads into contact with the surface of the doorknob. Although these areas 45 are only local, they are at a position where they can be manipulated effectively to enable an adult to transmit operating torque to the doorknob without removing the cover therefrom. Since these pads are more easily pressed into contact with the doorknob when located on segments 24, this location is preferred; but the pads are not limited thereto, since they may be placed at any position on the cover where they can be brought into contact with a suitable portion of the doorknob. Much depends on the stiffness of the material used for the cover in deciding on their location.
FIG. 11 illustrates another variational form of the invention in which cover 50 is divided along an axial plane into two halves which are hinged together by a suitable hinge 51. The halves are provided with a snap-type locking means as at 53 which can be engaged to hold the two halves in the position shown in the figure. By releasing the locking means, the two halves can be swung away from each other around hinge 51.
This construction permits the use of a rigid material. A cover 50 made of'such material cannot be expanded by virtue of its inherent elasticity to pass over the largest portion of the doorknob. For this reason, expansion in the size of the retaining means 54 is obtained by hinging the two sections so that they can be spread apart sufficiently to enable them to pass over the doorknob, after which the sections are brought together to contract the retaining means to hold the cover in place. The cover is held in closed position by lock 53. Assuming that the cover is made of metal, the normal coefficient of friction between two different metals is insuicient to permit transmission to the doorknob of operating torque. Being somewhat larger than the doorknob, only a very limited area of the rigid body at most can be brought into contact with the doorknob at any time, and as a result, the cover turns freely on the doorknob. Being rigid, it cannot be compressed to turn Ithe doorknob as previously described, as is possible when a soft, pliable material is used, and it is necessary to remove the cover to operate the doorknob in the normal manner, as was described in connection with the cover illustrated in FIGS. 1 and 2.
A further embodiment of the invention is illustrated in FIGS. l2, 13 and 14 wherein there is illustrated a twopiece cover indicated generally at 60. In all forms of the invention so far described, it has been assumed that the cover was being applied to a doorknob which was circular in cross-section, that is, one having a periphery which is a surface of revolution. This shape of the doorknob makes it possible for the cover when mounted on the doorknob to spin freely relative to the doorknob. However, there are times when it may be desired to apply the -cover to a non-circular doorknob, such as, for example, a polygonal doorknob 61, which, because of its shape, would make it relatively easy to turn the doorknob with the cover in place. This embodiment may also be applied to a lever-type doorknob.
To meet this situation, there is provided an adapter 63 'which typically is an annular member having a smooth,
cylindrical exterior surface 64 and an interior surface 65 which is adapted to conform to the shape of doorknob 61. Surface 65 is also shaped so `that the adapter, when once in place, cannot move axially of the doorknob. For this reason, the adapter is split into two halves along an axial plane. The two halves may be held together by any suitable means, as, for example, a pair of spring catches 66, located one at each of the opposite sides of the adapter in a recess 67 so that the spring catches do not project outwardly beyond the cylindrical outer surface of the adapter. Thus the adapter is mounted upon the doorknob to turn therewith and from this point of View can be regarded as a part of the doorknobv structure.
In combination with an adapter of this character, the doorknob cover 68 may be constructed in the same manner as cover 20 of FIGS. l and 2. The only difference 1n the operation is that cover 68 engages the adapter rather than doorknob 61 itself. However, it will be appreciated that the same principle of operation is still mvolved; and this is particularly true if the adapter is regarded as being a part of the doorknob which is installed for the purpose .of facilitating use of the cover in any of the forms previously described. v
One of the objects of the invention is to provide a security device of the character described not requiring any modification or alteration in the doorknob and generally adaptable to all styles and kinds of doorknobs. This is generally characteristic of the invention even though an adapter may be used on special types of doorknobs or under special situations. When the adapter is removed, the doorknob is restored to its original state; and the adapter is only a temporary addition as a part of the cover.
Other variations in the detailed design and construction of a doorknob cover may occur to persons skilled in the art without departing from the spirit and scope of the present invention. Accordingly, the foregoing disclosure is considered to be illustrative of, rather than limitative upon, the invention as defined by the appended claims.
1. A doorknob cover comprising:
a hollow body having a stiff annular wall and having an opening to admit a doorknob inside the body,
an elastic retaining means integral with the body and surrounding said opening,
said retaining means comprising a plurality of linger segments expandable to pass over the doorknob but normally occupying a contracted position engageable with the doorknob to yieldingly resist removal of the cover from the doorknob,
said finger segments extending angularly outwardly to form bends in said retaining means engageable with the doorknob and to provide free end portions on said linger segments bendable into frictional engagement with the doorknob,
said cover being of a material of sufficient stiifness to retain substantially its original size and shape under external manual pressure.
2. A vdoorknob cover as in claim 1 that also includes a locking member surrounding the elastic retaining means to prevent expansion thereof thereby to prevent removal of the cover from the doorknob while the locking rnember is in place, said locking member `being removable.
3. A doorknob cover as in claim 1 in which the interior surface of the nger segments has localized areas having a relatively higher coeicient of friction than the remainder of the interior surface, said areas being so located that they can be engaged with the doorknob.
4. A doorknob cover as in claini'l which also includes pads of a material having a higher cofficient of friction than the material of the cover, said pads being on the interior face of at least some of the nger segments at positions such that the pads can be engaged `with the doorknob.
References Cited by the Examiner UNITED STATES PATENTS 585,657 7/1897 Dickson.
853,537 5/ 1907 Dubisee. 2,610,877 9/1952 Weaver 292- 2,78l,220 2/ 1957 Zietlow 292--347 3,061,346 10/ 1962 Jorgensen.
EDWARD C. ALLEN, Primary Examiner.
RICHARD E. MOORE, Examiner.