The ulnar and median nerves—two of the three major nerves in the arm—are largely unprotected by muscles or bone. As a result, these nerves are prone to injury. Biker's Palsy, also known as Cyclist's Palsy and Handlebar Palsy, and Carpal Tunnel Syndrome (CTS) are two types of injuries caused by the compression of the ulnar and median nerves in the wrists. Both injuries are prevalent among cyclists and bikers because of the repetitive motion, vibration, and pressure exerted on their wrist joints for extended periods of time. However, these nerve injuries are also common in individuals who regularly grip or expose their hands to vibrating or impacting objects, such as steering wheels and handlebars of motor vehicles (e.g., cars, trucks, motorcycles, all-terrain vehicles), sports/recreational equipment (e.g., baseball bat, golf club, tennis racket), and construction machinery and tools (e.g., jackhammers, riveters, chain saws, hammers). Individuals whose hands are regularly exposed to repetitive motion, vibrations and pressure may also suffer from other medical conditions, including medial and lateral epicondylitis in the elbow, such as tennis elbow and golfer's elbow, De Quervain's tenosynovitis in the thumb and wrist area, calcific and bicipital tendinitis, and other impingement injuries experienced while serving in tennis or swinging in golf.
In order to prevent or reduce the likelihood of Biker's Palsy and CTS, damping devices have been developed to attenuate the vibrations transmitted through handles and steering mechanisms. Some of these devices incorporate a gas-filled bladder mounted to the surface of the vibrating handlebar or handgrip. One such device is described in U.S. Pat. No. 5,355,552 to Huang. Huang discloses a shock-absorbing air cushion grip which can be fixed around the handle of a tennis racket, hammer, bicycle, or a steering wheel. The grip has a cubic support structure with a plurality of air cells that can be isolated or be in fluid communication with each other. However, this apparatus does not provide a secure means for the grip to remain in stationary contact with the handle of the vibrating object. Specifically, the air cushion grip can rotatably move about the handle while it is grasped by a hand, and thereby diminishes the user's ability to maneuver or control the vibrating object. Further, the air cushion grip is equipped with only a one-way manually-compressible pump to inflate the air cells. Further still, the air-cushion grip lacks the capability to adjust, in real-time, the damping levels of the air cells in order to accommodate the different vibrations and/or shocks that the object and its handle experience.
U.S. Pat. No. 5,987,705 to Reynolds describes a vibration damping covering that attaches to a vibrating handlebar. The covering comprises a bladder having a plurality of independent or interconnected inflation cells filled with fluid, a tube for attaching an external pumping device, and a sensor for indicating when proper inflation pressure has been reached. The design of the covering, however, has several drawbacks. The covering does not integrate an inflation device to expand or contract the inflation cells. Also, the covering is not adapted to provide real-time, continuous adjustments of the damping level provided by the covering. Vibrations and impacts can vary in their frequency and amplitude, and as such, a single pressure damping level may not be sufficient in protecting a user's fingers, hands, wrists, arms, elbows and shoulders (herein “upper extremities”).
U.S. Pat. No. 4,421,181 to Andersson et al. is directed to a vibration damping arrangement having an air-tight chamber containing a gas at a pressure higher than ambient or atmospheric pressure. The chamber is glued to the surface of a vibrating handlebar and has a grip layer wrapped around the chamber. In some embodiments, more than one chamber is glued to the handle. However, the arrangement does not include an integrated gas inflation device or a control unit to adjust damping levels of the chamber based on vibration characteristics (e.g., frequency, amplitude) and the strength of the user's grip (i.e., the amount of pressure applied to the chamber when the user is gripping the chamber). Where multiple gas-filled chambers are involved, Andersson teaches that all chambers have the same internal pressure. Accordingly, the damping arrangement does not allow for independent configuration of the chambers and fails to provide localized damping, wherein different sections of the handlebar are provided different levels of vibration damping. Moreover, Andersson is not adapted to provide for real-time adjustments of the damping levels of the air-tight chamber.
U.S. Patent Application Publication No. 2010/0212453 to Rouillard et al. discloses a handlebar vibration reducing grip having an outer tubular element, an inner tubular element disposed within the outer tubular element, and a plurality of deformable ribs for coupling the inner and outer tubular elements together. The grip further incorporates gas-filled compartments formed between the ribs, inner tubular element, and outer tubular element. The vibrations transmitted by the handlebar are reduced by the deformation of the ribs as well as the deformation of the compartments and compression of the gas disposed therein. This design of a vibration reducing device has several drawbacks. The deformable ribs prevent the grip from providing sufficient damping for a range of vibrations—varying in frequency and amplitude—that may be exerted on the upper extremities. Further, the grip does not include an inflation device to adjust the volume of gas contained in the compartments. As such, the pressure levels of the compartments remain constant and therefore are not adapted to provide varying damping effects. The vibration reducing grip also does not remain stationary with respect to the handlebar. The grip can rotate about the handlebar while the hands are grasping the grip, which reduces the user's ability to control the vibrating object.
While the prior art damping devices attached on the outer surfaces of handlebars of vibrating objects provide some vibration attenuating benefits compared to the handlebars alone, they still suffer from several disadvantages. One such disadvantage is that these “exterior” damping devices may not remain rotatably stationary while mounted to the handlebars, and thus, may affect a person's ability to maneuver the vibrating object. Further, the damping devices, when properly filled with gas, may substantially increase the overall size (i.e., perimeter) of the handlebar. This makes gripping the handlebar, and in turn controlling the vibrating object, difficult. Another disadvantage of the prior art damping devices is that they fail to provide continuous, real-time adjustments of damping levels or cushion pressure to sufficiently protect the upper extremities from different forms of vibration. As such, the prior art damping devices provide limited vibration damping benefits at the expense of adequate control over the vibrating object.