Interlocking device

The specification discloses several embodiments of an interlocking device. The specification discloses a preferred embodiment of an interlocking device having an inner bar slideable within the confines of an outer bar. The outer bar has a first end and a second end. When the inner bar slides towards the second end of the outer bar, a plug, which is attached to the inner bar, is adapted to abut a plug barrier thereby preventing the inner bar from sliding towards the second end.The outer bar of the interlocking device further defines an interlocking member passage and an interlocking member stop. The interlocking device further has an interlocking member attached to the inner bar. When the inner bar slides towards the first end of the outer bar, at least a portion of the interlocking member moves transverse to the sliding axis of the inner bar and into the interlocking member passage. The interlocking locking member further abuts the interlocking member stop, thereby stopping the inner bar from sliding towards the first end of the outer bar. The interlocking device preferably has a cam attached to the outer bar and adjacent to the interlocking member stop. The cam may be actuated to release the interlocking member from the interlocking member stop thereby allowing the inner bar to slide through the confines of the outer bar.

FIELD OF INVENTION

The present invention relates to locks and fasteners. More particularly, the present invention relates to locks that mechanically interlock an inner member from sliding within the confines of an outer member.

BACKGROUND

Inner-Outer Member Combination

Various devices presently utilize inner members that are slidable within the confines of outer members (also referred to as “inner-outer member combination”). An inner-outer member combination allows a user to adjust a device's dimension. For example, some tow bars used for towing vehicles have legs that utilize the inner-outer member combination so that they can easily be stored when not in use. Camera tripods also utilize the inner-outer member combination so that they can be stored in a non-bulky manner.

Other devices that utilize the inner-outer member combination include: cleaning poles that allow users to extend the poles to reach a desired height and construction devices that extend to a certain height to transport and allow a person to work on an elevated area, such as billboards. The inner and outer members of these devices may have the same shape, but vary in diameter—that is, telescopic.

Locking Mechanism for Telescoping Legs

Telescoping legs are used in cleaning or agricultural tools (as disclosed in U.S. Pat. No. 5,154,449), legs of common camera tripods (as disclosed in U.S. Pat. Nos. 4,029,279 and 4,761,092), and musical instrument support (as disclosed in U.S. Pat. No. 4,430,017). All of these telescoping legs have a locking mechanism that stops the inner bar from sliding within the confines of the outer bar.

U.S. Pat. No. 5,154,449 discloses a lock for telescoping legs. The lock has a cylindrical clamp, a movable block, and an eccentric shield. The cylindrical clamp is actuated by pivoting the eccentric shield, which causes the shield to pinch the clamp to secure the outer tube and to press the movable block against the outer tube. See also U.S. Pat. No. 4,761,092.

U.S. Pat. No. 4,029,279 discloses another lock for telescoping tubular legs. The lock has a camming lever that engages an inner channel section through a window formed in the outer channel section, thereby locking the inner and outer members. See also U.S. Pat. No. 4,430,017.

One problem with the locks described above is that they are friction-based locks. Friction-based locks rely on friction to prevent an inner member from sliding within the confines of an outer member. However, friction may be overcome by a strong force. Thus, friction-based locks may only be appropriate for limited applications, such as when telescoping legs are used to support lightweight objects or when telescoping legs are not subjected to strong forces. Friction-based locks are also disclosed in U.S. Pat. Nos. 4,029,279, 4,761,092, and 4,430,017.

Tow Bars

Tow bars are devices used for enabling a carrier to tow another carrier. Tow bars are commonly used for enabling a recreational vehicle (an “RV”) to tow a car. Tow bars typically have a pair of legs attached to a leg coupler. The leg coupler attaches to a hitch or a ball mount of the towing vehicle. The other end of the tow bar legs attaches to the vehicle being towed.

A sample tow bar is disclosed in U.S. Pat. No. 5,382,042 ('042 reference), entitled “Towing Device Support.” The tow bar of the '042 reference has a cylindrical inner member that moves in two directions within a cylindrical outer member. In one embodiment, the cylindrical outer member has a latch attached to one end of the cylindrical outer member. The latch has a handle on one end and a stopping potion and a tooth on another end. The tooth is adapted to abut a dimple on the inner bar. The dimple is substantially a triangular shaped indentation on the inner bar. The tooth of the latch is adapted to go inside the indentation and abut the bottom of the dimple's triangle thereby preventing the inner bar from sliding toward the bottom triangle side. However, the inner member can still move in the opposite direction because the tooth can disengage from the dimple by sliding toward the crest of the dimple's triangle, as there is no structure designed to stop the tooth at the crest. When the tow bar is being used, the inner member's movement within the confines of the outer member exposes the tow bar to damage and possibly to the detachment of a vehicle being towed from the towing vehicle.

The '042 reference also discloses an embodiment where the inner and outer members are secured by a pin attached on the outer member. The pin is adapted to insert through an opening defined by the inner member, thereby interlocking the inner and outer members. The problem with using a pin as a locking mechanism is that it might break, especially when towing a heavy load.

Another problem with the '042 reference is that high friction builds in between the pin and the opening or in between the latch and the dimple when a vehicle is being towed. Because of this high friction, a user may not be able to remove the pin from the hole or the latch from the dimple when the user wants to slide the inner member within the outer member to, for example, store the tow bar. This situation is commonly known in the art as being in a “bind.” To get out of the bind, the user would have to re-board the towing vehicle and drive the towing vehicle back and forth until the friction is relieved off the pin. Driving the towing vehicle back and forth may not even remove the bind, especially when the towing vehicle and the vehicle being towed are on an uphill surface.

Another tow bar is disclosed in U.S. Pat. No. 5,957,477 ('477 reference). The '477 reference has two leg members that are attached by a slideable collar, which moves between a locked and an unlocked position. Each leg member has an inner member that has grooves and an outer member that has catches. The catches attach to the grooves when the collar is in a locked position, thereby interlocking both members. Like the tow bar previously described, the catches might disengage from the grooves, especially when towing a heavy load.

The '477 reference is also susceptible to “binding.” In fact, the '477 reference provides a separate release tool for a user to remove an inner bar that is “bound” with the outer bar. Thus, a tow bar that has little or no tendency to “bind” is desired. Additionally, a tow bar that has an integrated tool for releasing “bound” members is also desired because separate tools are easy to lose and are complicated to use.

BRIEF SUMMARY OF THE ASPECTS OF THE INVENTION

The applicant has therefore provided an interlocking device. In the preferred embodiment, the interlocking device has an inner bar, which has a confined end disposed within the confines of an outer bar. A plug is attached to the confined end of the inner bar. The inner bar is slideable within the confines of an outer bar. The outer bar has a first end and a second end. A plug barrier is attached to the second end. When the inner bar slides towards the second end of the outer bar, the plug is adapted to abut the plug barrier thereby preventing the inner bar from sliding towards the second end.

The interlocking device further has an interlocking member attached to the plug by a bolt. When the plug abuts the plug barrier, at least a portion of the interlocking member moves transverse from the sliding axis of the inner bar. The interlocking member inserts through an interlocking member passage, which is preferably defined by the top wall of the outer bar. The interlocking locking member further abuts an interlocking member stop, which is also preferably defined by the top wall of the outer bar. The inner bar is stopped from sliding towards the first end of the outer bar by the interlocking member and the interlocking member stop, and the inner bar is also stopped from sliding towards the second end of the outer bar by the plug and the plug barrier.

The interlocking device preferably has a cam attached to the outer bar and adjacent to the interlocking member stop. The cam may be actuated to release the interlocking member from the interlocking member stop thereby allowing the inner bar to slide through the confines of the outer bar.

Additional features of certain embodiments of the invention will further be described below. It is to be understood that the invention is not limited in its application to the details of the construction and to the arrangement of the components set forth in the following description or as illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Finally, it is understood that the scope of the present invention is to be determined by reference to the issued claims and not by whether a given embodiment meets every aspect of this brief summary or satisfies every deficiency or problem with the prior art as noted above.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now toFIG. 1, the preferred embodiment of an interlocking device20is shown. Interlocking device20has an outer bar24and an inner bar22. Outer bar24is preferably formed from a plurality of interconnected walls (only32and34are shown). The plurality of interconnected walls preferably define a rectangle-shaped outer bar and a square-shaped cross-section. The interconnected walls define a cavity within the outer bar, which is referred to as the confines of the outer bar. Alternatively, outer bar24may be formed from a hollow cylindrical tube.

Outer bar24has a first end26and a second end27. Second end27is also referred to as the receiving end. Outer bar24preferably has a collar28attached to receiving end27. Collar28is preferably cylindrical in shape. Collar28defines an inner bar passage29. In an embodiment without a collar, inner bar passage29may be defined by the plurality of interconnected walls at receiving end27.

Inner bar22enters the confines of the outer bar24through inner bar passage29and is slidable within the confines of outer bar24. Inner bar movement from receiving end27and first end26defines a sliding axis. Inner bar22is preferably in a sliding fit relative to inner bar passage29. The term sliding fit is used to refer to a configuration between members wherein a moving member has little or no room to deviate from the axis of movement. Thus, inner bar22preferably has little or no room to deviate from its sliding axis. The sliding fit configuration minimizes the generation of friction in the moving member, which may result in the moving member being difficult or impossible to move, or place the moving member in a “bind.” Inner bar22is preferably cylindrical in shape, but may be rectangular, triangular, or other shapes known in the art. Inner bar22is preferably made of steel, but may also be made of plastic, polymer, wood, or other materials known in the art.

With continued reference toFIG. 1, outer bar24has a cam mount30attached to one of the interconnected walls, preferably top wall32. Cam mount30may be attached in between receiving end27and first end26, preferably adjacent to receiving end27. Cam mount30has a base36and a bolt holder38. Bolt holder38preferably has two humps37positioned side-by-side. A channel39is formed in between humps37. Humps37are adapted to attach a bolt40in between channel39. Bolt40is adapted to rotatably attach a cam42. Cam42rotates within cam opening (not shown) defined by base36of cam mount30. Cam42preferably has an elongated handle44. Elongated handle44may be attached to cam42or may be built unitarily with cam42. Elongated handle44is preferably movable from 0 degrees to 180 degrees and within a rotational plane to actuate cam42.

Outer bar24and collar28are preferably made of steel, but may also be made of plastic, polymers, wood, or other materials known in the art. Outer bar24and collar28may have different shapes, such as cylindrical, triangular, or other shapes known in the art. Outer bar24and collar28may be attached together preferably by welding, or by using adhesives or fasteners known in the art. Outer bar24and collar28may also be built unitarily, such as by molding.

Referring now toFIG. 2, inner bar22has a first end62and a second end64. Second end64is preferably disposed inside the confines of outer bar24. Second end64is also referred to as the confined end. A plug66is attached to confined end64of inner bar22. A plug barrier67adapted to abut plug66is attached to outer bar24adjacent to or at receiving end27. In the preferred embodiment, plug barrier67may be a bushing attached to outer bar24. Bushing may define an opening (not shown inFIG. 2) continuous with inner bar passage29. The diameter of the opening may be smaller than the plug diameter so that plug66can abut the bushing. In an alternative embodiment, plug barrier67may be collar28having a diameter smaller than the diameter of plug66so that plug66can abut collar28. In yet another embodiment, plug barrier67may be receiving end27that defined inner bar passage29. Receiving end27may have defined inner bar passage29with a diameter smaller than plug66so that plug66can abut inner bar passage29.

When inner bar22slides in the direction towards receiving end27, plug66eventually abuts a plug barrier67. Plug66and plug barrier67therefore stop inner bar22from further sliding towards receiving end27and from detaching from outer bar24. In the preferred embodiment, plug barrier67is preferably made of steel, but may be made of other materials known in the art, such as plastic, rubber, polymer, wood, and the like. Plug66is preferably shaped like inner bar22, but has a larger diameter than inner bar22. Of course, plug66may be of various shapes. Plug66is preferably in a sliding fit relative to outer bar24. Inner bar22is also preferably in a sliding fit relative to plug barrier67.

In the preferred embodiment, a bolt70attaches a block72to plug66. Bolt70may also attach block to confined end64of inner bar22. Bolt70is preferably disposed parallel to the sliding axis of the inner bar and substantially in between top wall32and bottom wall of outer bar24so that bolt70slides with inner bar in the sliding axis. Block72preferably extends over bolt70, and portion of block72preferably defines a dome surrounding a portion of bolt70. Cross-section of block72preferably tapers from bottom to top, so as to form a wedge-shaped structure.

Block72is movable from a first position where block72is substantially parallel to the sliding axis of inner bar22to a second position where block72moves transverse from the sliding axis of inner bar22. In the preferred embodiment, a biasing device74, such as a spring, is placed around bolt70. When block72is moved to the second position, biasing device74moves block72transverse from the sliding axis of inner bar22, and preferably the edge of the wedge goes into block passage76. Block passage76may be an opening defined by top wall32. Top wall32preferably define block stop78. Block stop78may also be defined by cam mount base36. Block stop78abuts the edge of the wedge. Thus, block72and block stop78prevent inner bar22from further sliding in the direction towards first end26of outer bar24.

It can thus be seen fromFIG. 2that a positive mechanical interlock locks inner bar22within the confines of outer bar24. Inner bar22cannot slide further in the direction towards second end27of outer bar. Inner bar22also cannot slide in the direction towards first end26of outer bar. Thus, it can be seen that, unlike friction-based locks disclosed in prior art, virtually no amount of force or pressure applied in the direction of the sliding axis of inner bar22can cause inner bar22to slide, unless components interlocking inner bar22with outer bar24are destroyed.

Referring now toFIG. 3A, cam mount30and cam42are preferably positioned adjacent to block passage76. Cam42may be actuated by rotating cam handle42within its rotational axis. Cam42pushes block72against biasing pressure of biasing device74until block72is released from block passage76and block stop78. Once block72is released, inner bar22may slide in the direction towards first end26of outer bar24. A close up view of the cam area, the area around cam42, is shown in FIG3B.

It is noted that the portion of block72, which does not insert through block passage76, is preferably sized to provide a sliding fit between said portion and the outer bar. Thus, block72has protrusion83reflecting the change in the block size from the portion of the block that inserts through the block passage to the portion of the block that is preferably sized to provide the sliding fit. As discussed above, the sliding fit feature helps prevent inner bar22from deviating from its sliding axis.

Referring now toFIG. 4, a cross-sectional view of interlocking device20is shown wherein inner bar22(shown inFIGS. 1-3) is locked from sliding within the confines of the outer bar. Block76(shown inFIGS. 1-3) has moved to the second position where it is transverse from the sliding axis of inner bar22. Biasing device74is further shown to be parallel with the sliding axis of inner bar22so that biasing device74is adapted to move with inner bar22.

Referring now toFIG. 5, a cross-sectional view of interlocking device20is shown wherein cam42is actuated to release block72from block stop78. When cam42is actuated, cam42rotates with cam opening45. A portion of cam42further extends through cam mount30, block passage76, and the confines of outer bar24, thereby pushing block72against biasing device74to release block72from block stop78. Once block72is released from block stop78, inner bar22may slide in the direction towards first end26of outer bar24.

It can thus be seen fromFIGS. 2,4, and5that while interlocking device20provides a positive mechanical interlock between inner bar22and outer bar24, interlocking device20also allows a user to conveniently unlock the positive mechanical interlock by simply rotating cam handle44.

Referring now toFIG. 6, the preferred environment of use for interlocking device20is shown wherein interlocking device20is used for a tow bar system. A tow bar system may have one tow bar leg or a plurality of tow bar legs. In the most preferred embodiment, interlocking device20is used as tow bar legs for a tow bar system having two tow bar legs. Each tow bar leg has an outer bar end93and95and an inner bar end97and99. Outer bar ends93and95attach to a leg coupler92in substantially a y-shaped configuration. Leg coupler92attaches to a connecting bar98, which attaches to a towing carrier100. Inner bar ends97and99attach to a base assembly102. Base assembly102attach to a carrier being towed104. Base assembly102, leg coupler92, and connector98are well known in the art.

It can thus be seen that when certain embodiments of interlocking device20are used as a tow bar leg, interlocking device20provides a tow bar leg that has an inner bar mechanically interlocked with an outer bar. This positive mechanical interlock minimizes the risk of the inner bar detaching from the outer bar as the inner bar is stopped from sliding at one end by the plug and the plug barrier and from sliding at the other end by the block and the block stop. Thus, the positive mechanical interlock minimizes the chances for a vehicle being towed to separate from the towing vehicle.

Additionally, the sliding fit feature of some of the components of interlocking device20help prevent the inner bar from being misaligned within the confines of the outer bar. This feature allows interlocking device20to avoid the instance where, especially during disassembly and storage of the tow bar, the inner bar becomes difficult or impossible to slide within the outer bar because of friction. Interlocking device20further allows a user to conveniently unlock the inner bar interlocked with the outer bar by simply actuating a cam. This feature is especially helpful in contracting the size of the tow bar for storage.

Besides being used as tow bar legs, it should be appreciated that interlocking device20may also be used for devices using inner and outer members. Additionally, interlocking device20may be used for devices wherein the ability to adjust the devices' dimensions is a desired feature. As examples, interlocking device20may be used for construction devices that extend to a certain height to transport and allow a person to work on an elevated area, such as billboards. Interlocking device20may also be used for camera tripods, surveying equipment, cleaning equipment, and agricultural tools. Interlocking device20may further be used for support devices that have adjustable legs. When interlocking device20is used in the above applications, interlocking device20offers a sturdy positive mechanical interlock between members, a “bindless” inner and outer bar, and a convenient locking mechanism.

CONCLUSION