HK1029031B - Tamper resistant rotational locking mechanism for an enclosure - Google Patents

Description

Anti-interference rotatable locking mechanism of shell

Background

The present invention relates to a simple and low cost locking mechanism, and in particular, the locking mechanism also prevents unlocking with a wad without the need for a key.

Simple, low cost locking mechanisms, such as those used to lock lavatory dispensers, can be unlocked by rotation of a key into a cam twister assembly causing movement of a cam. Such a cam twister assembly includes an exposed surface and includes a square recess that mates with a key of square cross-section. The locking mechanism is designed to be unlocked by a plug without a key, and is cost effective and easy to use. The locking mechanism can be actuated without a key by inserting an object such as a pen, pencil or screwdriver into the exposed surface of the cam twister or into the square recess with a finger and rotating the locking mechanism. The friction between the surface of the cam twister and the finger (or object) is sufficient to allow sufficient torque to be applied to rotate the cam twister, thus opening the mechanism without the need for a key.

Objects and aspects of the invention

It is a primary object of the present invention to provide a locking mechanism which, while simple and inexpensive, prevents unlocking with a plug without the use of a key as required.

Another main object of the present invention is to provide a rigid casing with an access door that is secured by a locking mechanism that, although simple and inexpensive, prevents unlocking with a wad without the use of a required key.

Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

To achieve these objects and in accordance with the purpose of the invention, as embodied and broadly described herein, a latch mechanism of the present invention is incorporated into a component of a rigid housing and clamps an access opening into the interior of the housing. The access opening in the interior of the housing may be provided with a door that is part of the housing and includes an interior surface that faces the interior space of the housing when the door is closed. At least one hook member can extend from an inner surface of the door.

The locking mechanism includes a rotor sleeve, a star cam twister, and a latch member. The latch member is shaped and arranged such that axial movement of the latch member unlocks the locking mechanism. The latch member includes at least one hook member shaped and arranged to engage a corresponding hook member on the door to secure the door and close access to the interior space of the housing.

The star cam twister provides a rotating member with an axial recess for receiving a key. The star cam twister is rotatably disposed relative to the rigid housing and is fixed against axial movement relative to the rigid housing.

The rotor sleeve is rotatably disposed relative to the rigid housing and is fixed against relative axial movement. The rotor sleeve is spaced from the star cam twister such that rotation of the rotor sleeve does not rotate the star cam twister. However, the rotor sleeve has an axially extending through bore which is aligned with the axial recess of the star cam twister.

The dimensions of the entry of the star cam twister and the through-hole in the rotor sleeve are complementary so that any key that conforms to the dimensions of the through-hole in the rotor sleeve can be inserted into the entry of the star cam twister in a manner that allows the key to turn the star cam twister. One end of the latch member is shaped to engage an end of the star cam twister such that rotation of the star cam twister causes axial movement of the insert. However, one arrangement axially biases the latch member in the latched position. The latch member is shaped and arranged to unlock the locking mechanism against axial movement of the latch member of the biasing member.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the principles of the invention.

Detailed description of the drawings

FIG. 1 is a front elevational view of a preferred embodiment of the present invention, a wall-mounted paper dispenser, with the dotted line representation indicating the layout of the physical elements in the view shown;

FIG. 2 is a partial cross-sectional view and a partial side view in perspective view from the direction indicated by the arrow 2- -2 of FIG. 1, with the portions indicated by chain lines indicating the open configuration of the door assembly;

FIG. 3 is a partial cross-sectional view and a partial side elevational view in perspective from the direction indicated by the arrow 3- -3 of FIG. 2;

FIG. 4 is a partial cross-sectional view and partial side elevational view in perspective from a direction similar to that shown in FIG. 3;

FIG. 5 is a schematic illustration of the components and location of the preferred embodiment of the present invention;

fig. 6 is a fragmentary side elevational view in perspective from the direction indicated by the arrow 6-6 of fig. 4, with the locking position indicated by the chain-dotted line and the unlocking position indicated by the solid line.

Detailed description of the preferred embodiments

Reference will now be made in detail to the preferred embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided to explain the present invention and is not to be construed as limiting the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment, can be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. Like numbers refer to like elements throughout the drawings and description.

The locking mechanism of the present invention is intended to close access to the interior of a rigid housing and the locking assembly is located within the housing. The present invention functions in a locking mechanism where axial movement of the latch member selectively causes the operating mode of the locking mechanism to be switched from locked to unlocked and vice versa. Furthermore, in the locking mechanism according to the invention, the rotary movement of the key produces the required opening movement of the bolt by means of the shape of the cam, which is interposed between the bolt and the rotary member on which the key is placed. In addition, the locking mechanism can function without regard to the orientation of the relative force of gravity.

A preferred embodiment of the locking mechanism according to the invention is indicated by the solid line in fig. 2 and the dash-dot line in fig. 1 and by the numeral 20. The locking mechanism is contained within a component of a rigid housing 22, which in the embodiment shown in FIG. 1 is a paper dispenser. The rigid housing 22 is of rigid plastic material and has a transparent plastic door 23 hinged adjacent the side of the door 23 opposite the mechanism 20. The door 23 is locked and closed near the mechanism 20. As shown by the dotted line in fig. 2, the door 23 is opened by rotating a hinge (not visible in fig. 1 and 2) in a direction away from the plane of fig. 1 and toward the viewer. As shown in fig. 2, the door 23 has at least one hook 26, and the required three hooks 26 are symmetrically arranged in height along the surface of the door 23 facing the inside of the rigid casing 22 and adjoining the locking mechanism 20. In addition to the components relating to locking mechanism 20, and more particularly locking mechanism 20, which will be described more fully below, the remaining components of rigid housing 22 are embodied, positioned, and function as described in application 08/534179, which is incorporated herein by reference.

The locking mechanism of the present invention includes a star cam twister having a rotating member with an axial entry for receiving a key. As shown in fig. 5, the star cam twister 30 forms a longitudinal axis 31. The star cam twister 30 is preferably cylindrical and is symmetrically disposed about the central longitudinal axis 28. The star cam twister 30 thus constitutes a first axial extension comprising a first end 31 and a second end 32 opposite the first end. Within the outer surface of the star cam twister 30 is a circumferentially extending slot 33 intermediate the first end 31 and the second end 32. As shown in fig. 5, the groove 33 is used to rotatably receive the stopper 34.

As shown in fig. 2-4, the star cam twister 30 is rotatably mounted within the rigid housing 22 formed by the dispenser. As shown in fig. 3 and 4, the first end 31 of the twister 30 passes through an opening with a circular cross-section in the flange 24, which is also part of the interior of the rigid housing 22. The star cam twister 30 is rotatably held by the stopper 34 and the shoulder 35. As shown in fig. 5, shoulder 35 is integrally formed as part of the outer surface of twister 30 and extends peripherally thereabout. The stop 34 and shoulder 35 prevent axial movement of the star cam twister 30 relative to the rigid housing 22, but allow relative rotational movement.

As shown in fig. 3 and 5, an axially extending first opening 36 forms an entrance in the first end 31 of the star cam twister 30. The transverse cross-sectional shape of the first opening 36 is a star shape having a vertex 37, etc., which is an acute angle. As shown in fig. 4 and 5, the second end 32 of the star cam twister 30 is an axially extending first cam member 38 surrounded by a cylindrical wall 39. The first cam member 38 is configured to engage a cam mounting member 46 (described below) such that rotation of the cam mounting member effects opening of the locking mechanism through the first cam member 38. As shown in FIGS. 4 and 5, the axial cross-section of the first cam member 38 is a generally triangular cross-section.

As shown in FIG. 1, an axially extending latch member 40 is mounted for axial movement relative to the interior of the rigid housing of the dispenser. As shown in fig. 2, each of a plurality of spaced ribs 43 formed in rigid housing 22 is slidably mounted within a corresponding C-shaped guide track 44, C-shaped guide track 44 being integrally formed along the length of latch member 40. As shown in fig. 2, the latch 40 has at least one hook member 45 in the first end 41 for selectively engaging and disengaging the mating hook member 26 to lock and unlock the locking mechanism, respectively. In the illustrated embodiment, three hooks 45 are provided, the hooks 45 being equally spaced along the length of the latch member 40.

As shown in fig. 4 and 5, the latch member 40 has a second end 42 with a cam mounting member 46 for engaging the first cam member 38 of the star twister 30. The cam mount 46 is shaped such that when the cam member 38 is placed along the undulating surface of the cam mount 46, rotation of the cam member 38 causes axial movement of the latch members 40.

The invention provides a means of biasing the latch member against axial movement caused by rotation of the first cam member 38 seated on the cam mounting member 46. As shown and incorporated in fig. 2, the means for biasing the latch member 40 against axial movement caused by rotation of the first cam member 38 includes a compression spring 47. As shown in fig. 3, at least a section of the spring 47, in this case the first end 48 of the spring 47, is fixed against axial movement relative to the rigid housing. As shown in fig. 3 and 4, another segment of spring 47, in this case, a second end 49 of spring 47 is positioned opposite first end 48 of spring 47, and a second end 49 of spring 47 is positioned opposite stop 25 associated with latch member 40. So arranged and positioned, the spring 47 biases the latch members 40 to remain in the latched position, acting when the hook members 45 of each latch member 40 are engaged with their respective mating hook members 26.

The locking mechanism of the present invention also includes a rotor sleeve. As shown in fig. 3 and 5, a rotor sleeve 50 defines a second axially extending cylindrical member including a first end 51 and a second end 52 opposite the first end. As shown in fig. 3 and 5, the rotor sleeve 50 is rotatably supported in the inner space of the rigid housing by the stopper 27. As shown in fig. 3, the second end 52 of the rotor sleeve 50 nests within the counterbore of the opening 29 through the outer wall of the rigid housing 22. The retainer 27 is fixed in a groove 53 (figure 5) around the outer circumference of the rotor sleeve 50 and collides with the inside of the inner wall of the dispenser, which is the inside of the rigid housing 22 and allows the rotor sleeve 50 to rotate freely within the opening in the outer wall of the dispenser.

As shown in fig. 3, a first end 51 of rotor sleeve 50 is disposed away from and toward a first end of star cam twister 30. An axial gap, which should be a minimum of 1/16 feet, must be maintained between the rotor sleeve 50 and the star cam twister 30. As shown in fig. 3 and 5, the first end 51 of the rotor sleeve defines a second opening 54 extending axially to form a second inlet. As shown in fig. 3, the second opening 54 is aligned with the first opening 36. Furthermore, as shown in fig. 3 and 5, the transverse cross-section of the second opening 54 is shaped so that it can be non-rotatably mounted within the star-shaped cross-section of the first opening 36 of the star cam twister. In other words, the key 55, which has the same transverse cross-sectional shape as the second opening 54, can be inserted into the first opening 36 and non-rotatably retained within the first opening 36 of the star cam twister 30. In the embodiment shown, the first opening 36 is selected to be star-shaped, with a top corner, and the second opening 54 and the key 55 are of complementary square shape. However, other complementary geometries can be used to accomplish the same function. For example, an equilateral triangle, star geometry, can be used for the first opening 36, and a complementary equilateral triangle for the second opening 54 and the key 55.

In operation, axial movement of the latch member 40 selectively causes the locking mechanism to be switched from the locked to the unlocked operating mode and vice versa. Star cam twister 30, stops 25, 27, 34, latch member 40, compression spring 47, rotor sleeve 50, and key 55 are shown in a general view in fig. 5. All of these components except the key 55 are enclosed in the rigid housing 22, which in this case happens to be a paper dispenser. The only exposed surface of the mechanism is the circular second end 52 of the rotor sleeve 50, which rotor sleeve 50 includes a square through bore 54. The rotor sleeve 50 is securely fixed within the opening 29 in the housing 22 by the retainer 27. However, the rotor sleeve 50 is free to rotate 360 degrees clockwise and counterclockwise. Axially disposed, but spaced apart from the first end 51 of the rotor sleeve 50 is a star twister 30. The first opening 36 of the star cam twister 30 is arranged so that the star (fig. 5) is axially aligned with the square toward and through the bore 54 of the rotor sleeve 50. The second end 32 of the star cam twister 30 includes a cam member 38 that engages a cam receiving member 46 of the latch member 40.

The retainer 34 securely retains the star cam twister 30 within the housing 22 and prevents the star cam twister 30 from moving axially relative to the housing and rotor sleeve 50. However, when a torque of at least 6 foot pounds is encountered, the stop 34 allows full 360 degrees of clockwise or counterclockwise rotation of the star cam twister 30 about its central axis. The amount of torque required to effect rotation of the star cam twister 30 is a function of the strength of the compression spring 47, which exerts an axial force that determines how much torque is exerted on the axially arranged latch members 4.

To control the rotation of the locking mechanism of the present invention, the key 55 is inserted into the rotor sleeve 50, which includes a through bore 54 that matches the transverse cross-sectional shape and size of the key 55. With the key uniquely inserted into the second opening 54 of the rotor sleeve 50, rotating the key 55 at this point will not unlock the mechanism, as only the rotor sleeve 50 will rotate. The key 55 must also be able to be inserted axially until the key encounters the star geometry of the first opening 36 of the star cam twister 30. At this point, rotating the key 55 will cause the square cross-section of the key 55 to align with one of eight possible angular engagement positions within the star cam twister 30. At this point, the key will be non-rotatably clamped relative to the star cam twister 30 and a minimum torque of about 6 foot pounds will rotate the star cam twister 30, which allows the rotary locking mechanism to be opened, thus opening the lock mechanism

The housing of the embodiment.

To understand the interference rejection features of the present invention, consider the following. Once the so-called obturator determines that the rotor sleeve 50 is the entry to the locking mechanism, the obturator can try to open the mechanism by applying an axial force at the second opening 54 of the rotor sleeve 50. However, the tamping device does not achieve the desired breaking effect. Rotating the rotor sleeve 50 with one finger only rotates the rotor sleeve 50. The axial clearance between the rotor sleeve 50 and the star cam twister 30 prevents the translation of rotational movement between these two components through frictional engagement.

The same undesirable effect occurs if the stuffing device forces a stuff such as a pen, pencil or rasp blade into the square opening 54 of the rotor sleeve 50 and rotates the rotor sleeve. Rotating the rotor sleeve does not rotate the star cam twister 30. Forcing any object larger than opening 54 into rotor sleeve 50 produces the same nullifying effect.

Any object, regardless of shape, smaller than the opening 54 in the rotor sleeve 50 will successfully pass through the rotor sleeve 50 and, if axial movement continues toward the rotor sleeve, will come into contact with the star cam twister 30. However, since the object is smaller than the second opening 54 in the rotor sleeve 50, rotation of the object will not allow it to enter any locked position in the first opening 36 of the star cam twister 30 for engagement. The star cam twister 30 requires that the object have the exact size and shape of the key 55. Thus, the tampon will only rotate within the first opening 36 of the star cam twister 30 and will not rotate the star cam twister 30. Any friction that can be generated is not significant enough to overcome the rotational resistance generated by the compression spring 47.

The object is smaller overall and of different cross-section than the opening 54 in the rotor sleeve 50, but one side of the object is the same size as the opening 54, with the same result for such an object. Such as a knife, or a straight wire knife or, although less likely, a triangular tool.

By combining the rotor sleeve 50 with a unique location and shape of the star cam twister 30, which star cam twister 30 comprises the first opening 36 with geometric compatibility and the second opening 54 of the rotor sleeve 50, the locking mechanism of the present invention prevents the locking mechanism from being opened with any tool other than a key 55 with a corresponding geometric shape.

While the preferred embodiments of the present invention have been described in specific terms, such are for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims. In the embodiment shown in the drawings, the rotor sleeve and the star cam twister function as a rotational locking mechanism, described in more detail in application 08/534179, and hereby incorporated by reference. The novel features of these assemblies are useful with other rotary-type locking mechanisms. These new assemblies prevent actuation of the rotational locking mechanism except by having a defined key (fig. 5), as exemplified above.

Claims (8)

1. A tamper resistant locking mechanism for restricting access to the interior of a rigid housing, comprising:

a star cam twister defining a longitudinal axis, the star cam twister defining a first axially extending member including a first end and a second end disposed opposite the first end, the first end of the star cam twister defining an axially extending first opening having a star-shaped transverse cross-section, the second end of the star cam twister having an axially extending first cam member, the star cam twister being rotatably clamped within the interior space of the rigid housing, the cam member being shaped to engage the receiving member of the cam; whereby rotation of said first cam member effects opening of the locking mechanism;

a rotor sleeve rotatably clamped within the interior space of the rigid housing, the rotor sleeve forming a second axial extension, the second axial extension includes a first end and a second end opposite the first end, the rotor sleeve having an axially extending second opening, the opening being adapted to receive a key therein and to allow the key to pass therethrough, the opening transverse cross-section being received within and non-rotatably retained within said star cross-section of said first opening of said first star cam twister, the first end of the rotor sleeve is disposed away from and toward the first end of the star cam twister, the arrangement of the rotor sleeve with respect to the star cam twister defines an axial gap between a first end of the rotor sleeve and a first end of the star cam twister, the axial gap preventing the star cam twister from contacting the rotor sleeve; and

an axially extending latch member including a first end configured to selectively engage and disengage a hook member to lock and unlock the locking mechanism, respectively, said latch member including a second end having a cam receiving member disposed to receive said first cam member.

2. The apparatus of claim 1 wherein said first cam member and said cam seating member are shaped such that rotation of said cam member effects axial movement of said insert member.

3. The apparatus of claim 2, further comprising:

a means for biasing said latch member to resist axial movement caused by rotation of said first cam member.

4. The apparatus of claim 3, wherein said means for biasing said latch member against axial movement comprises a spring including at least one fixed portion for resisting axial movement relative to the rigid housing.

5. A rigid enclosure with tamper resistant features that restrict access to the interior space of the enclosure, comprising:

a wall defining a rigid enclosure and surrounding an interior space;

a star cam twister defining a longitudinal axis, the star cam twister defining a first axially extending member including a first end and a second end disposed opposite the first end, the first end of the star cam twister defining an axially extending first opening having a star-shaped transverse cross-section, the second end of the star cam twister having an axially extending first cam member, the star cam twister being rotatably clamped within the interior space around the wall of the rigid housing, the cam member being shaped to engage the cam receiving member;

a rotor sleeve rotatably clampable within the interior space around the wall of the rigid housing, the rotor sleeve defining a second axial extension including a first end and a second end opposite the first end, the rotor sleeve having an axially extending second opening for receiving a key therein and permitting the key to pass therethrough, the opening being seated in transverse cross-section within the star cross-section non-rotatably retained within the first opening of the first star cam twister, the first end of the rotor sleeve being disposed away from and toward the first end of the star cam twister, the disposition of the rotor sleeve with respect to the star cam twister defining an axial gap between the first end of the rotor sleeve and the first end of the star cam twister, the axial clearance prevents the star cam twister from contacting the rotor sleeve; and

a door formed in said wall and having an inner surface facing the interior space when closed, said door forming at least one hook extending from said inner surface;

an axially extending latch member including a first end configured to selectively engage and disengage a hook member to lock and unlock the locking mechanism, respectively, said latch member including a second end having a cam receiving member disposed to receive said first cam member.

6. A rigid casing according to claim 5, characterised in that the shape of the cam member and the cam seating member causes rotation of the cam member to effect axial movement of the insert member.

7. The rigid shell of claim 6, further comprising:

a means for biasing said latch member to resist axial movement caused by rotation of said first cam member.

8. The rigid housing of claim 7 wherein said means for biasing said latch member against axial movement includes a spring including at least one fixed portion for resisting axial movement relative to the rigid housing.