Patent Application
20130322957
This invention allows for two concentric tubes or extrusions (hereafter all referred to as “tubes”) with similar cross sections differing in size to float freely, one inside the other, until the invention is activated at which time the tubes' relative positions become rigidly fixed. The invention may then be deactivated, allowing the tubes to again float freely. The invention may be activated at arbitrary points, and more than one of the invention may be used to join several tubes. Activation and deactivation does not permanently alter or damage the structure of the invention or the tubes.
Many jobs require the performance of specific tasks in inconvenient locations. Inexhaustive examples include painting a high wall or retrieving debris from the center of a large pool. Building temporary structures like scaffolding or bridges which allow workers closer proximity to a given task are time consuming and expensive to construct, or are heavy and awkward to transport, and often require additional precautions to use safely. Frequently, available workspace around task sites cannot easily or safely accommodate a human being, but removal or modification of material to enlarge or make safe a site is rarely viable or economical.
Laborers in search of alternatives increasingly consider ways to extend their reach rather than bring their own bodies closer to the task. A vital tool is a pole or staff which holds an implement at one end that can be manipulated or operated by a worker at the other. Poles of any sizable length are awkward to transport, which has given rise to design of telescoping or collapsible poles made of concentric cylindrical tubes of varying diameters. Such poles can be easily expanded to much greater lengths and made temporarily rigid as to prevent contraction without intervention from the worker.
With the advent of cam locks, telescoping poles can easily accommodate arbitrary lengths without losing rigidity. However, existing cam lock designs suffer from several problems. First, existing designs are prone to breakage under lateral stress typically present in many applications. Weight is also of significant concern. Ideally, rigidity and integrity should be maintained and weight minimized for the cam lock to be effective. Second, when damaged or broken, field repair is impractical, often necessitating complete replacement of the entire telescoping pole. Third, existing cam locks do not easily accommodate tubes of varying diameters, as parts are often specific to one diameter. Finally, there is a need for cam lock designs that allow for passage of material inside the tube beyond the cam lock's installed location. Current designs do not allow fluid to drain through the center of telescoping pole, nor do they allow control wires to run through the center of the pole to a tool or device on the end opposing the worker. Where electrical tools are operated on telescoping poles with such cam locks, wires are typically either be wrapped around the pole or dangle alongside, creating additional inconvenience and safety concerns.
What is needed is a low cost, compact, lightweight and durable cam lock that can be quickly and easily repaired onsite without requiring undue replacement of components.
In its basic embodiment, the cam lock comprises a male body and a female body, the male body having a protruding spindle offset from its center and the female body having a cavity capable of accommodating the spindle. The cavity on the female body is typically, but not necessarily offset in proportion to the offset of the spindle on the male body. The shape of the spindle and the cavity are typically cylindrical with circular bases to facilitate the spindle rotating inside the cavity. The male body and female body are also typically cylindrical with circular bases, but further embodiments employ bases which are elliptical or based on other shapes. The top of the spindle is flared such that the outer diameter of the flared portion is larger than the diameter of the cavity. This allows for the spindle, once passed all the way through the female cavity, to remain there.
One cam lock body is sized to fit snugly in the end of the smaller of two tubes. The opposing or free-spinning body is sized such that when the free-spinning body is rotated around the spindle axis, the width of the resulting silhouette becomes larger than the interior of the larger of the two tubes. When the rotation is performed by manipulating the smaller tube while the free-spinning body is inside the larger tube, the free-spinning body is pushed against the side of the larger tube, creating enough friction to prevent the manipulation of the two tubes in relation to each other, forming a rigid implement. When the effect is no longer desired, the tubes may be rotated in a counter direction to relieve the friction, allowing the tubes to once again move freely in relation to each other.
In a further embodiment, n cam locks can be used with n+1 tubes to create a pole with multiple locking segments where n is a positive integer.
In a further embodiment, the cam lock body, to be inserted into the smaller tube, has a ledge or rib preventing insertion beyond a certain point, that body having an outer wall roughly the same size as, or very slightly larger than the interior of the tube, thereby preventing separation once inserted, and the ledge or rib having a size at least slightly larger than the interior of the tube, but preferably larger than the exterior of the tube. This is typically, but not necessarily, the female body.
In a further embodiment, the cam lock body, to be inserted into the larger tube, has a flexible tab which protrudes from the side of that body. This allows that body to have contact with the interior wall of tubes of varying sizes such that a single size body may accommodate several sizes of larger tubes. This is typically, but not necessarily, the male body.
In a further embodiment, both male and female cam lock bodies and the spindle are hollow, allowing material to pass through the cam lock without affecting its function. In one example application, fluid can drain from the interior of one tube through the cam lock into the neighboring tube. In another example application, a wire or other control mechanism can be run through the interior of a telescoping pole.
In a further embodiment, both male and female cam lock bodies and the spindle are hollow and the male cam lock body has one or more thin membranes. The membrane restricts material from passing through the cam lock without affecting its function. The membrane can be removed or punctured by the user to allow material to pass through if desired. The membrane is affixed to, constructed along, or formed at any point along the hollow portion or at the ends of the male cam lock body.
In a further embodiment, a punctured membrane may be replaced by the user, again restricting material from passing through the cam lock.
In a further embodiment, the flared end of the spindle has one or more notches so that it may be contracted, and the spindle removed from the cavity with greater ease, allowing for the separation of the male and female bodies without requiring special tools so as to allow onsite repair.
In a further embodiment, a reinforcement ring is inserted into the spindle after the spindle is passed through the cavity. This prevents the flared end from contracting, and prevents removal of the spindle from the cavity until the reinforcement ring is removed. The reinforcement ring also increases rigidity and structural strength of the spindle which further resists deformation or breakage during use. Because the reinforcement ring is also hollow, materials may flow through the cam lock as described above without hindering its function.
In a further embodiment, the reinforcement ring is held in place by an adhesive.
In a further embodiment, the interior of the spindle is shaped so as to prevent the reinforcement ring from becoming dislodged. This allows the entire cam lock to be quickly assembled from parts and used immediately without additional time to cure.
The following describes preferred embodiments. However, embodiments of the invention are not limited to those embodiments. Therefore, the description that follows is for purpose of illustration and not limitation.
The female construction 2 further comprises a female body 4, a cylindrical spindle cavity 5 centered about a spindle cavity axis 23, and optionally a radial cutaway or countersink 27 on the end of the spindle cavity 5 accommodating the flared end 10 upon entry into the spindle cavity 5. The diameter of the spindle cavity 5 is typically less than that of the flared end 10 and greater than that of the spindle body 9. The spindle cavity axis 23 is offset from the female body center axis 25.
The male construction 3 further comprises a male body 6, a male body shoulder 7, and a cylindrical spindle 8 protruding from the male body shoulder 7. The spindle 8 is centered about a spindle axis 24. The spindle 8 further comprises a spindle body 9 and a flared end 10. The spindle axis 24 is offset from the male body center axis 26. The spindle body further comprises a spindle outer wall 11.
Optionally, the female body further comprises a rib or ledge 13 having a size larger than the exterior of the smaller tube 21 but smaller than the opening 30 of a guide fitting 29. The guide fitting 29 is secured to the end of the larger of two tubes 22, thereby preventing separation of the tubes until the guide fitting 29 is removed, irrespective of whether the cam lock is in the locked position. Alternatively, a depression ridge 28 in the end of the larger tube 22 could be used instead of the guide fitting 29 to provide a similar function.
Typically, the male construction 3 is free spinning to accommodate the interior of the larger tube 22. The male body 6 further comprises a male body outer wall 14 smaller than the interior of the larger tube 18, and typically a flexible drag tab 15 protruding from the male body outer wall 14. The drag tab 15 contacts the inner wall of the larger tube 22. Alternatively, the cam locking device could be manufactured whereby the male body 6 is inserted into the smaller tube 21, and the female construction 2 is free spinning, in which case the female body 4 would further comprise a flexible drag tab similar to that depicted.
The male body 6 and the spindle 8 are typically hollow, the male body 6 further comprising a male body inner wall 16, and the spindle further comprising a spindle inner wall 17. This is to allow material to pass through the device without affecting its function. Optionally, the male body inner wall 16 and the spindle inner wall 17 may be of different centers and shapes.
Where the male body 6 and the spindle 8 is hollow as described above, the flared end 10 typically further comprises cutaways or notches 18 to allow the flared end 10 to flex more easily while passing through the spindle cavity 5. Typically, the cam locking device 1 further comprises a reinforcement ring 19. The outer diameter of the reinforcement ring 19 is roughly the same as the diameter of the spindle inner wall 17. The reinforcement ring 19 is positioned on the interior of the spindle 8 near the flared end 10 to increase structural strength or to prevent the flared end 10 from passing back through the spindle cavity 5 while the reinforcement ring 19 is in place.
The reinforcement ring 19 is held in place by a locking means which includes, but is not limited to: an adhesive; friction; or surface characteristics of the spindle interior wall 17 and optionally the reinforcement ring outer wall 20 such as notches, grooves, ridges, bumps, protrusions, depressions, etc.
Typically, but not necessarily, the spindle axis 24 and the spindle cavity axis 23 are offset in similar proportions or by the same amount.
The invention is typically, but not necessarily, manufactured from rigid plastic to reduce cost and weight.
