Title:
KEYHOLE COVER LOCK
United States Patent 3732711


Abstract:
A lockable cover for a keyhole is provided. The keyhole cover includes a housing that is secured to the outside surface of the door adjacent the lock thereof. A plate that is slidably received in the housing is movable between covering and uncovering positions with respect to the keyhole. A plurality of tumblers are journaled in the housing with each of the tumblers being provided with a plurality of radially extending holes in the body portion thereof. All of the holes in the tumblers except one are relatively shallow in depth, the remaining hole in each of the tumblers being of greater depth sufficient to receive a plurality of pins that are integral and movable with the plate. The plate is normally in a covering position over the keyhole and can be moved therefrom to the uncovering position only when the greater depth hole in all of the tumblers is aligned with the pins on the plate. The aforementioned Abstract is neither intended to define the invention of the application which, of course, is measured by the claims nor is it intended to be limiting as to the scope of the invention in any way.



Inventors:
ALBERT M
Application Number:
05/178272
Publication Date:
05/15/1973
Filing Date:
09/07/1971
Assignee:
ALBERT M,US
Primary Class:
Other Classes:
70/287, 70/312
International Classes:
E05B17/14; (IPC1-7): E05B13/00; E05B37/12
Field of Search:
70/425,455,284,287,288,312,158,5,63,67,71,81,213,443
View Patent Images:
US Patent References:
1078156N/A1913-11-11Locher



Foreign References:
IT338842A
IT400124A
GB282268A
CH187380A
IT655936A
Primary Examiner:
Craig Jr., Albert G.
Claims:
What I claim as new and desire to secure by Letters Patent is

1. A keyhole cover lock comprising:

2. The keyhole cover lock in accordance with claim 1 wherein there is further included means for retaining said tumblers.

3. The keyhole cover lock in accordance with claim 2 wherein said tumblers each include an annular undercut, said retaining means comprising a ring-like member positioned in each said undercut and arranged to bear against the portion of said housing.

4. A keyhole cover lock comprising:

5. The keyhole cover in accordance with claim 4 wherein the exterior surface of each said tumbler includes a series of indicia marked thereon, the indicia being equal in quantity and in location so as to coincide with the first and second depth holes, said housing including an index mark adjacent each said tumbler.

6. The keyhole cover in accordance with claim 4 wherein there is further included a retainer plate secured to the rear surface of said housing and positioned intermediate said housing and the door.

7. The keyhole cover in accordance with claim 4 wherein the longitudinal axis of said pins is aligned with the rotational axis of said tumblers.

8. The keyhole cover lock in accordance with claim 4 wherein there is further included means for normally biasing said plate into said covering position.

9. The keyhole cover lock in accordance with claim 8 wherein said biasing means comprises a spring having one end thereof secured to said housing, the other end of said spring being secured to said plate.

10. The keyhole cover lock in accordance with claim 4 wherein there is further included stop means for limiting the movement of said plate when said plate is moved to the uncovering position.

Description:
BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to locks and more particularly to a secondary lock adapted to normally cover the keyhole of a primary lock.

2. Description of the Prior Art

Because of the increasing crime rate, home owners are becoming more conscious of burglar alarm systems and burglar proof locks. In the latter field, many advances have been made in locks so as to render the opening thereof by unauthorized people considerably more difficult. One example of such an improvement is the magnetic key that is encoded such that only one key can open a magnetic tumbler lock. In addition, combination locks that are relatively pick proof have also been suggested for doors of dwellings. One form of combination lock requires the sequential depression of specific push buttons while other combination locks are more conventional in that they have a rotatable dial. However,where a keyhole is provided with the lock, as opposed to a combination lock, it is virtually impossible to assure that an experienced burglar will not be able to pick the lock. This is primarily so because the keyhole is readily accessible.

SUMMARY OF THE INVENTION

The present invention overcomes the basic shortcomings in the prior art keyhole type locks in that it provides lockable means for concealing the keyhole. A plate that is slidably mounted in a housing is normally positioned in a covering relationship with the keyhole and can be moved therefrom only by the manipulation of a plurality of combination type tumblers. The present invention also goes one step further and overcomes the shortcoming in the conventional combination lock in that, by providing a plurality of radial holes of two different depths, in each tumbler, it is impossible to "feel" when the pins are aligned with the holes. Only when the proper arrangement of tumblers is known, can the deeper hole in each of the tumblers be aligned with a respective pin so that the plate that is covering the keyhole can be retracted. The housing in which the present invention is contained is secured to the door from the inside thereof and the tumblers are rotatably journaled in the housing. As an additional feature, the present invention also provides means for biasing the plate into a normally covering position.

Accordingly, it is an object of the present invention to provide an improved keyhole cover lock.

It is another object of the present invention to provide an improved keyhole cover lock that is operated by means of a plurality of tumblers.

A feature of the present invention is that the tumblers, as described above, do not present a special "feel" when they are in the position that will permit the covering plate to be retracted.

These and other objects, features and advantages of the present invention will, in part, be pointed out with particularity, and will, in part, become obvious from the following more detailed description of the invention, taken in conjunction with the accompanying drawing, which forms an integral part thereof.

BRIEF DESCRIPTION OF THE DRAWING

In the various figures of the drawing, like reference characters designate like parts. In the drawing:

FIG. 1A is a fragmentary, elevational view illustrating the present invention mounted in a horizontal position on a door;

FIG. 1B is a fragmentary, elevational view similar to FIG. 1A but illustrating the present invention mounted vertically on a door above the keyhole;

FIG. 2 is an enlarged, front elevational view of the present invention with the door being shown fragmentarily;

FIG. 3 is a plan view of the present invention;

FIG. 4 is a rear elevational view, taking along line 4--4, with portions broken away for clarity;

FIG. 5 is a fragmentary plan view;

FIG. 6 is a fragmentary plan view, partially in section and similar in orientation to FIG. 5, but illustrating an alternative embodiment of the present invention; and

FIG. 7 is a fragmentary, front elevational view, partially in section, illustrating the operation of two basic components comprising the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring first to FIG. 1A and to FIG. 1B, there is shown the keyhole cover lock 10 comprising the present invention in a horizontal position and a vertical position, respectively. In a manner to be described more fully hereinafter, the keyhole cover lock 10 is suitably secured to the door D adjacent the keyhole K. In FIG. 1A, the keyhole K is covered and uncovered manually whereas in FIG. 1B the keyhole K is covered due to the force of gravity and is uncovered manually. The manner of usage of the present invention will be clarified subsequently.

Turning now to FIGS. 2, 3 and 4, the keyhole cover lock 10 comprising the present invention is shown in greater detail. The keyhole cover lock 10 is comprised of a housing 12 on the front surface of which three rotatable tumblers 14a, 14b and 14c are mounted. The rear surface of the housing 12 is provided with a channel 16 in which is slidably mounted a plate generally designated by the reference character 18.

As shown, for example, in FIG. 4, each of the tumblers 14a, 14b and 14c are provided with a plurality of radially extending holes 20 of relatively shallow depth, as well as one radially extending hole 22 of relatively greater depth. In addition, the front face of each tumbler 14a, 14b and 14c is provided with a plurality of indicia such as letters or numbers marked thereon conforming in location and quantity to the holes 20 and 22. In the embodiment illustrated, the numbers on the front face of the tumblers 14a, 14b and 14c each range from zero to seven. Thus, as will be described more fully hereinafter, there are a total of 512 possible combinations where three tumblers 14 each having eight different angular positions are used. It should be understood, however, that either more or less numbers on the face of the tumblers 14 and radial holes in the body of the tumblers 14 may be provided within the scope of the present invention.

The plate 18 is provided with an enlarged end section 24 that is adapted to be moved from a covering position to an uncovering position and vice versa with respect to the keyhole K, in a manner to be described more fully hereinafter. The body portion 26 of the plate 18 is also provided with a plurality of integral pins 28a, 28b and 28c that are in the same plane as the radial holes 20 and 22. The pins 28a, 28b and 28c are positioned so as to intercept the rotational axis of the tumbers 14a, 14b and 14c.

A cover or retainer plate 30 is secured to the rear surface of the housing 12 by means of fasteners, such as screws 32. The housing 12 may then be secured to the front surface of the door D by means of fasteners 34 which are screwed in from the inside of the door so that the housing 12 may not be removed by unauthorized parties.

Referring now to FIGS. 4 and 5, there is shown one means for rotatably capturing the tumblers 14. An annular groove 36 is formed in the body portion of the tumbler 14 intermediate the holes 20, 22 and the head portion of the tumbler. Three holes 37 are formed in the housing 12 with the axes of these holes being perpendicular to the axes of the tumblers 14a, 14b and 14c. A retaining pin 38 is inserted in each of the holes 37 such that the retaining pin 38 is engaged in the undercut 36. From the rear surface of the housing 12, below the cover plate 30, a set screw 40 is threaded into the housing so that it bears against and firmly locks in place the retaining pins 38.

FIG. 6 illustrates an alternative embodiment of the retaining means. The tumblers 14 are journaled in a counterbored hole 42 and a retaining ring 44 is placed in the undercut 36. Preferably a low friction washer 46 is positioned intermediate the retaining ring 44 and the transverse face of the counterbored hole 42.

The end portion 24 of the plate 18 may be placed in a normally covering position by orienting the keyhole cover lock 10 in a vertical position as shown in FIG. 1B. Alternatively, spring means 50 may be used for this purpose as shown in FIG. 4. One end of the spring 50 is secured to the plate 18 as shown by the reference character 52. The other end of the spring 15 terminates at a post 54 that is rigidly connected to the housing 12.

As shown in FIG. 4, stop means 56 integral with the housing 12 may be used to limit the inward movement of the plate 18.

The operation of the keyhole lock cover 10 will now be described in connection with FIGS. 2 and 4. As shown in FIG. 2, index markers 58a, 58b and 58c are formed on the front surface of the housing 12 adjacent the tumblers 14a, 14b and 14c, respectively. When the numbers 007 are in alignment with the index markers 58a, 58b and 58c, respectively, only the greater depth hole 22 of each tumbler 14 will be in alignment with the pins 28a, 28b and 28c, so that the plate 18 may be moved to the right as shown in FIG. 2 to thereby uncover the keyhole K. Only when the tumblers 14 are in this particular arrangement can the three pins 28 enter the greater depth holes 22. When one of the tumblers is out of position, such as the tumbler 14a, as shown in FIG. 7, the pin 28a will be adjacent one of the small holes 20 in he tumbler 14a so that the plate 18 cannot be moved to the right even though the pins 28b and 28c are aligned with the larger depth holes 22 in the tumblers 14b and 14c.

It should be particularly noted at this time that the tumblers 14 comprising the present invention overcomes the shortcomings found in prior art combination locks in that it is impossible to "feel" the different depth of the holes. All the holes will feel the same and in order to overcome the action of the keyhole cover lock it is either necessary to know the correct sequence of the tumblers or to try all of the 512 different combinations that are possible with three tumblers each having eight holes but only one of which in each tumbler is of greater depth than the others.

There has been disclosed heretofore the best embodiment of the invention presently contemplated. However, it is to be understood that various changes and modifications may be made thereto without departing from the spirit of the invention.