US 3362040 A
Description (OCR text may contain errors)
1968 v. w. GURZENIDA 3,362,040
LOCKING DEVICE Filed July 25, 1966 VERNON W. GURZENDA INVENTOR wwffiw TTORNEYS United States Patent 3,362,040 LOCKING DEVICE Vernon W. Gurzenda, Somerset, Pa., assignor to Rockwood Manufacturing Company, Rockwood, Pa., a corporation of Pennsylvania Filed July 25, 1966, Ser. No. 567,550 Claims. (Cl. 1686) The present invention relates to an improved locking device, and more particularly to a tamper-proof locking device which cannot be opened without destruction of the apparatus which houses the locking device.
In many applications, it is desirable that means he provided to prevent tampering or unauthorized disassembly of the apparatus in question. For example, it is known that people are prone to remove objects such as door stops from motels, public buildings and the like.
It is a primary object of the pesent invention to provide an improved locking device.
Another object of the present invention is to provide apparatus comprising an improved tamper-proof locking device which is of simple construction.
Still another object of the present invention is to provide an improved door stop having locking means to prevent removal of the door stop from the surface to which it is attached.
In a broad aspect, the present invention comprises a pair of cooperating, relatively rotatable members, said members cooperating to form an internal chamber, a spring detent secured to one of said members, the other of said members having cam means adapted to compress the spring detent upon relative rotation of the two members, and recess means provided in the cam surface. Upon continued relative rotation between the two members, the compressed spring detent upon reaching the vicinity of the recess expands into the recess to prevent further relative movement between these members and to prevent disassembly of the apparatus.
The above and other objects, features, and advantages of the invention will become more apparent as this description proceeds.
In the drawings:
FIGURE 1 is a perspective view of a door stop in accordance with the present invention;
FIGURE 2 is a vertical cross-sectional view showing the door stop of FIGURE 1 attached to a supporting surface;
FIGURE 3 is a view illustrating the relationship between a base plate which carries the spring detent and a housing member which is provided with internal cam surfaces which cooperate with the spring detent when the housing is placed in position upon the base plate and rotated relative thereto; and
FIGURE 4 is a view partly in section taken along a section line substantially perpendicular to the section illustrated in FIGURE 2.
Referring now to the drawings, and more particularly to FIGURE 1, there is illustrated a door stop having a housing generally designated by reference numeral 10, and a resilient bumper 12 which is secured within an upstanding annular projection 14 of the housing.
FIGURE 2 illustrates the door stop secured to a supporting surface 16 such as a wall or door. The housing has a cylindrical wall 18 with one end thereof abutting the surface 16 to form a completely enclosed internal chamber 20. The door stop is secured to the wall by means of a screw 22 which extends through an aperture 24 in a base plate 26 which abuts the surface 16. The screw has a head 28 which fits into a cylindrical opening 30 in the rear of surface of bumper 12. The plate 26 may have projections 32 which extend into surface 16, or other suitable means, for preventing rotation of the plate relative to surface 16.
As is best show in FIGURE 3, plate 26 has a pair tapering configuration are positioned on the inner surface with apertures through which ends 36 of a spring detent 38 project. In the illustrated embodiment, the spring detent 38 is generally semi-circular in cofiguration and its ends are normally biased outwardly. The lugs 34 function as stops to maintain the spring detent in a compressed condition.
A pair of opposed cam surfaces 40, 42 of arcuately tapering configuration are positioned on the inner surface of the cylindrical wall 18. Preferably, the cam surfaces are integral with the wall 18. A locking recess 44 is machined out of each cam surface, with the two recesses being essentially at opposite ends of a diameter line drawn through the center of the device. The function of the recesses 44 will be described hereinafter in connection with the procedure for assemblying the door stop.
In assemblying the door stop, the plate 26 is secured to surface 16 by screw 22. With the spring detent 38 positioned as shown in FIGURE 3, the portion of the device shown at the right hand side of FIGURE 3 is placed upon plate 26 with the lugs 34 and the spring detent 38 ex tending into chamber 20'. The normal distance between the outermost tips of the spring detent ends 36 is slightly smaller than the diameter of chamber 20. The housing 10 is now rotated relative to plate 26 in a clockwise direction until the ends 36 of the spring detent contact the leading faces of the cam surfaces 40, 42. Further rotation of the housing causes the ends of the spring detent to be pressed inwardly towards each other by the cam surfaces so that the spring detent is compressed. When the ends of the spring detent come into alignment with the locking recesses 44, the spring detent ends 36 snap outwardly into recesses 44 to permanently lock the housing 10 to plate 26.
Although the locking assembly of the present invention has been described for purpose of illustration as embodied in a door stop, it will be appreciated that the locking mechanism may find utility in other structures where it is useful to substantially permanently secure one portion of a device to another. Furthermore, various changes in the configuration of the spring detent may suggest themselves to those of ordinary skill in the art upon consideration of the present disclosure. For example, one end of the spring detent might be permanently fastened in which case only one recess 44 would be employed. In view of the foregoing, it is intended to encompass all such changes and modifications as fall within the scope of the appended claims.
What is claimed is:
1. Apparatus comprising a pair of cooperating relatively rotatable members, a spring detent secured to one of said members, a cam surface provided on the other of said members and positioned to compress said spring detent upon relative rotation between said members when in the operating position thereof, a locking recess provided in said cam surface and positioned to be in alignment with an end of said spring detent and to receive said end upon expansion of the compressed spring detent into said recess, and means to enclose said spring detent in its locked position to prevent access to said spring detent.
2. Apparatus according to claim 1, wherein said other member comprises a housing having a wall portion disposed about said spring detent.
3. Apparatus according to claim 2, wherein said cam surface is integral with the inner surface of said wall.
4. Apparatus according to claim 2, wherein said housing includes an upstanding annular projection, and fur- 3 ther comprising a resilient bumper secured within said projection.
5. Apparatus according to claim 1, further comprising a pair of opposed apertured lugs secured to said one member, said spring detent having its ends disposed within the apertures in said lugs, and said lugs constituting stops limiting the outward expansion of said spring detent.
6. Apparatus according to claim 1, further comprising means to maintain said spring detent in a normally compressed condition.
7. Apparatus according to claim 6, wherein said one member comprises a substantially flat plate.
8. Apparatus according to claim 7, further comprising a support surface, and means to secure said plate to said support surface.
9. Apparatus according to claim 7, wherein said means for maintaining the spring detent in a compressed con- References Cited UNITED STATES PATENTS 334,819 1/1886 Stoddard 292-353 1,847,228 3/1932 Smith 292256.65 2,899,703 8/1959 Johnson 16 86 3,050,770 8/1962 Morse et al. 16-86 BOBBY R. GAY, Primary Examiner.
J. L. KOHNEN, Assistant Examiner.