Abstract:
An ergonomic hand grip assembly is provided for attenuating shocks and impacts and reducing discomfort occasioned by use. The assembly includes a novel slotted sleeve member disposed between an elastomeric outer cover and an inner control member.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 USC §119(e) of U.S. Provisional Patent Application No. 61/387,044, filed Sep. 28, 2010. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to shock and impact-attenuating hand grips. More specifically, the invention relates to hand grips particularly suited for use with machines that tend to transmit shocks to the musculoskeltal extremities of the machine operator, such as the handle bars of motorcycles, off-road mountain bikes, all-terrain vehicles, and the like. 
     In off-road cycling, whether self-propelled, as in mountain biking, or powered by an internal combustion engine, as in a motorcycle, or riding an all terrain vehicle (ATV), the rider tends to grip the handle bars tightly for balance and control. Under competitive conditions, the rider may need to enhance his/her grip for prolonged periods of time while traversing difficult terrain conditions. Such tight gripping by the rider tends to cause shocks and impacts, to be transferred to the rider&#39;s hands, wrists, forearms and related musculoskeletal extremities that need to twist as and the handle bars are pivoted toward and away from the rider. Over a period of time, these various forces can induce fatigue, and fatigue can compromise riding enjoyment and competitive results in racing. 
     Although attempts have been made to provide handle-bar grips that are comfortable to use, ones that are too-soft do not provide adequate motion control. Ones that provide good motion control tend to be too-stiff to be comfortable. Thus, there is a need for a handle bar grip that is comfortable to use, that provides precise motion control, that has good endurance, and that can be readily retro-fitted on existing handle bars. 
     A primary object of the invention is to provide a novel hand grip assembly that includes a durable mounting sleeve located between an outer elastomeric grip and an inner handle bar for attenuating shocks and vibrations from the handle bar and for accommodating precise movement of the handle bar while being gripped tightly by the user. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing objects, features and advantages of the invention should become apparent from the following description taken in conjunction with the following drawings in which: 
         FIG. 1  is a perspective view of an ergonomic hand grip assembly mounted on a tubular handle bar shown in phantom lines; 
         FIG. 2  is an exploded perspective view in reduced scale of the ergonomic hand grip assembly illustrated in  FIG. 1 ; 
         FIG. 3  is an enlarged fragmentary plan view of one of the components of the assembly illustrated in  FIG. 1 ; 
         FIG. 4  is a longitudinal sectional view, in reduced scale, taken on line  4 - 4  of  FIG. 1 ; 
         FIG. 5  is a greatly enlarged sectional view taken on line  5 - 5  of  FIG. 4 ; 
         FIG. 6  is view, similar to  FIG. 5 , but illustrating the grip engaged by a user&#39;s hand shown in phantom lines; and 
         FIG. 7  is a developed fragmentary plan view of the grip assembly taken between lines  7 - 7  of  FIG. 6 ; 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
       FIG. 1  illustrates an ergonomic hand grip assembly  10  constructed in accordance with the invention. As best seen in  FIG. 1 , the assembly includes an outer resilient cover  11  having an open proximal end  12  surrounded by an annular flange  13 . The cover  11  is preferably molded of elastomeric material, such as rubber, that provides a satisfactory co-efficient of friction with respect to the palm of a human hand H when gripped as shown in  FIG. 6  adjacent the cover flange  13 . The elastomeric material is of conventional rubber-like composition known in art for use on outdoor equipment having a handle bar control member  15 , such as illustrated in phantom lines in  FIGS. 1 and 2 . The control member  15  has a free end portion  16  which is moveable by a user&#39;s hand H to provide control motion inputs to a vehicle (not shown) and to assist the vehicle rider in maintaining balance while riding the vehicle. 
     In order to isolate unwanted shocks and impacts that would normally be transmitted to a user&#39;s hand by a conventional grip, the preferred embodiment of the invention includes a novel sleeve member  20  interposed between the control member  15  and the resilient cover  11 . As best seen in  FIG. 2 , the sleeve member  20  is elongate and tubular and has a proximal end portion  21  and a distal end portion  22 . The sleeve member  20  has a length which is slightly longer than the width of a large human hand, to accommodate various hand sizes of riders. A length in a range of about 4-6 inches is adequate for most applications. 
     The proximal end portion  21  of the sleeve member  20  is disposed toward the vehicle steered by the handle bar  15 . The distal end portion  22  is disposed away from the vehicle. The proximal end portion  21  of the sleeve member  20  is adapted to telescopically receive the free end portion  16  of the handle bar control member  15 . The distal end of the sleeve has an end wall  23  ( FIG. 4 ) which is adapted to engage the end of the handle bar when fully telescopically engaged as illustrated in  FIG. 4  with the resilient cover  11  in place. 
     To provide a highly desirable level of interaction between the handle bar and the outer cover, the sleeve member  20  is provided with a series of apertures which are preferably elongate slots,  31 ,  32  ( FIG. 3 ,  FIG. 7 ) adjacent its proximal end portion. Each slot extends completely through the sleeve wall, and each slot is open throughout its entire extent. The elastomeric cover spans across the slots. The size, shape, number, and spacing of the slots is selected to provide the sleeve  20  with a substantially linear elastic torsional spring rate on the order of about two (2) pound inches per degree of angular deflection in opposite clockwise and counterclockwise directions relative to a neutral un-stressed condition. In other words, within a total range of angular deflection of 45 degrees, 22.5 degrees clockwise, such as in the clockwise direction CW as shown in  FIG. 6 , and 22.5 degrees counterclockwise relative to a relaxed, unstressed state M, the amount of angular deflection increases at a linear rate with respect to applied torque. A preferred material for the sleeve member  20  is a thermoplastic polyamide, such as “nylon 12”, which is readily moldable into the sleeve configuration illustrated. 
     The elongate slots  31 ,  32  provide the desired level of elastic torsional deflection and fatigue resistance. To this end, the slots  31 ,  32  are elongate lengthwise of the sleeve and define a series of elongate, somewhat hour-glass shaped strips of sleeve wall material between them. The slots extend for a distance of less than about one-half the overall length of the sleeve, and more preferably, they extend for less than about one-quarter of the overall sleeve length. Preferably, the sleeve has an overall tubular length of about 4 inches, a diameter of about one inch, and a wall thickness of about 0.060 inch. 
     A majority of the slots have a length of about one (1) inches and a maximum medial width of about 0.1 inch. Each of the slot side walls bows outwardly from opposite curved ends such as  31   a ,  31   b  toward the median of each slot. The slots have a length to average medial width ratio of about 10 to 1. 
     A pair of the slots, located diametrically opposite one another  33 ,  34  are open at their proximal ends to accommodate a clamping action provided by a pair of integral semi-circular collar portions,  35 ,  36  connected together by a pair of clamping screws  37 ,  38 . When the screws are tightened, the collar portions  35 ,  36  tightly engage the handle bar  15  to mount the assembly in place. 
     In the preferred embodiment illustrated, the slots are equally spaced apart in the body of the sleeve  20 , on centers of about 0.2 radians. All of the majority of slots have an identical closed-ended shape, and there are eight (8) in number. The slots extend in side-by-side relation about the periphery of the sleeve  20 . With the two open end slots, the total number of slots is ten (10). A slightly greater, or lesser, number of apertures may be provided, and their shapes may be varied, but with some degradation in performance from the best mode as disclosed. 
     The sleeve member  20  extends closely adjacent the outer surface of the control handle bar  15  with a clearance on the order of 0.010 inch. See  FIG. 6 . The cover  11  tightly engages the outer surface of the sleeve  20 . The coefficient of friction between the sleeve member  20  and the handle bar  15  is less than the coefficient of friction between the sleeve member  20  and the resilient cover  11 . This provides a desired level of rotational motion between the sleeve  20  and the control member  15  even when the resilient cover  11  is tightly gripped in the manner as illustrated in  FIG. 6 , and when the cover  11  is twisted. 
     Torsional fatigue tests on a prototype of the preferred embodiment exhibited an endurance of only slightly less than 500,000 cycles at a maximum total torsional deflection of 30 degrees, i.e. 15 degrees clockwise and 15 degrees counterclockwise, on opposite sides of torsionally unstressed neutral datum. 
     In the disclosed embodiment, all the slots are open and extend completely through the sleeve wall. There may be situations in which the user may wish to tune the grip to suit the user&#39;s personal preference for various conditions of use. In such event, the sleeve may be manufactured with slots that do not extend completely through the wall, but which have thin-walls as-manufactured, that can be broken away, or punched through with a hand tool, to enable less than all the slots to be opened-up for adjusting the performance characteristics of the sleeve. 
     In view of the foregoing, it should be apparent that the disclosed embodiment of the invention provides a durable and comfortable grip that is capable of being manufactured economically. 
     While a preferred embodiment has been described in detail, various modifications, alterations and changes may be made without departing from the spirit and scope of the invention as defined in the appended claims.