Patent Publication Number: US-2004052576-A1

Title: Apparatus for optimizing the attachment of a hub structure to an axle

Description:
FIELD  
       [0001] The present invention relates in general to motorized land vehicles, and in particular to apparatus for optimizing the attachment of a hub structure to an axle.  
       BACKGROUND OF THE INVENTION  
       [0002] Stability and traction are important for motorized land vehicles. Stability is the vehicle&#39;s tendency to resist inertia force during a change the magnitude or direction of motion. Traction is the vehicle&#39;s tendency to grip the surface upon which it moves. Both affect performance and safety. Without sufficient stability and traction, a vehicle may spinout or tip over, causing damage and injury.  
       [0003] Although stability can be controlled by the vehicle driver through skilled acceleration, braking, and steering, traction can be substantially controlled through vehicle configuration. That is, by proper vehicle weight distribution, or more specifically, by the position of the vehicle&#39;s center of gravity (CG) relative to the ground. CG is a virtual point through which inertial forces appear to act on the vehicle. Adjusting the CG closer to the ground tends to improve the vehicle&#39;s traction, and hence reduce the driver skill required to maintain stability. Excess traction, however, may cause the vehicle to have poor performance, and maneuver sluggishly.  
       [0004] A common way to influence CG, and hence the resulting traction, is to adjust the size of the wheelbase. Wheel base may be measured as the distance on the rear axel from one tire to another. Widening the wheelbase increases traction, while narrowing it reduces it. The proper wheelbase setting can empirically determined by first observing vehicle performance and driver skill, and then adjusting the wheelbase appropriately. The ability to quickly modify the wheelbase is advantageous in many situations, particularly when the vehicle is used for racing competition, such as in go-cart racing.  
       [0005] Originally a recreational pass time, go-cart racing has become an almost semi-professional sport with organized teams and expensive stylized go-carts. Go-carts often achieve speeds of 75 MPH over the course of several laps. Racing organizations, such as Allkart International, hold go-cart races year-round on dedicated tracks made of dirt, clay, macadam, asphalt or concrete materials.  
       [0006] The typical racing go-cart is a relatively simple motorized vehicle large enough to accommodate only one individual, consisting of a tubular frame with a generally single-cylinder engine, without the differential gear and suspensions. A go-cart frame is usually formed from segments of steel tubing rigidly welded together, and the rear axle is connected to this frame by means of rigid bearing hangers.  
       [0007] In the discussions that follow, the term “tighten” is employed herein to discuss moving a fastener into a securing structure. Likewise, the term “loosen” is employed herein to discuss moving a fastener out of a securing structure. Furthermore, the term screw should be understood to apply to other types of fasteners, such as bolts, clips, and pins.  
       [0008]FIG. 1 illustrates a simplified diagram of a go-cart chassis  100 . Front axle  110 , is normally comprised of a fixed width wheelbase, and provides a steering mechanism for the vehicle. That is, wheels  112   a - b  rotate left or right in response to corresponding movements in steering column  114 . Rear axle  104  is often connected to an engine, through a drive chain or belt. Rear wheels  106   a - b  are commonly attached to rear axle  104  through some type of clamp assembly  102   a - b.  In a common method, clamp assembly  102  securely clamps the wheel hub of wheel  106  to a position along axle  104 . During a race, this wheel hub position can be adjusted, modifying the wheel base.  
       [0009]FIG. 2 illustrates a simplified diagram of a clamp assembly  200 . The hub of wheel  106 , shown in FIG. 1, is commonly attached to the hub by a fastener, such as a lug, bolt, or screw, through a hub attachment mechanism, such as flanges  208   a - b.  Axle  104 , also shown in FIG. 1, is commonly inserted through end  204 , sliding into the clamp assembly clamping cavity. The diameter of the clamping cavity is commonly 1/1000 th  of an inch larger in size than the diameter of the axle for which it has been designed. Clamp assembly  200  further comprises an expansion slot  206 , which allows the compression of clamp assembly  200  around the axle. Normal to expansion slot  206  is clamping screw  202 . By tightening clamping screw  202 , expansion slot  206  is compressed from a neutral point to a point in the compression range of the expansion slot, reducing the diameter of the clamp assembly clamping cavity, and subsequently securing it around axle  104 , as shown in FIG. 1.  
       [0010] FIGS.  3 A-B illustrate simplified diagrams of expansion slot  206  cavity. It should be noted that in FIGS.  3 A-B, the relative positions of clamp assembly components, as well as the degree of expansion slot wall bending, are not necessarily drawn to scale. FIG. 3A illustrates a clamping screw  302  and the expansion slot  303  in a neutral position wherein the walls of the cavity are substantially parallel. In this position, the clamp assembly is not compressed around an axle, and so can freely slide. FIG. 3B illustrates a clamping screw  302  and the cavity  303 , wherein clamping screw  302  has been tightened by an amount  308  to a compression position, wherein the walls of the expansion slot bend toward each other, compressing the hub attachment structure, and allowing it to be secured to an axle.  
       [0011] In practice, however, the current clamp assembly is difficult to quickly adjust in a safe manner, without damage occurring to the clamp assembly, and without the use of multiple tools. It is common for the diameter of the clamp assembly clamping cavity to be about 1/1000 th  inch larger than the axle it surrounds. During a race, the ambient temperature around the axle may be sufficiently high to cause it to expand outward toward the hub attachment structure, substantially reducing the 1/1000 th  inch clearance gap, and effectively binding one body to the other. Furthermore, foreign material, such as dirt particles, mud, or small rocks may have become logged in the cavity between the clamp assembly and the axle. This foreign material can create excessive friction between the inside surface of the cavity and the outer surface of the axle, again effectively binding one body to the other.  
       [0012] Loosening a clamp assembly that is clamped to an axle commonly requires at least three separate tools: a hammer, a wedge, and a wrench. The screw would first be loosened with the wrench. The wedge would then be placed in the expansion slot and struck with the hammer, causing the expansion slot to expand beyond the neutral position into a position in its expansion range, at which time the clamp assembly is substantially free of the axle.  
       [0013] However, since the clamp assembly is commonly made of machined aluminum, striking it with a hammer and wedge can cause aesthetic damage to the clamp assembly&#39;s outer surface, impacting the general stylized appearance of the go-cart. It also can over-stress the hub attachment structure&#39;s structural integrity, substantially reducing its useful life. Furthermore, since adjustments are usually done quickly, the use of a hammer to strike a wedge can substantially increase the risk of injury.  
       [0014] In view of the foregoing, there is desired an apparatus for optimizing the attachment of a hub structure to an axle.  
       SUMMARY OF THE INVENTION  
       [0015] These and other features of the present invention will be described in more detail below in the detailed description of the invention and in conjunction with the following figures.  
       [0016] The invention relates, in one embodiment, to a clamp assembly for attaching a hub structure to an axle. The clamp assembly includes a tubular structure having a longitudinal axis. The clamp assembly also includes a hub attachment mechanism and an axle clamping mechanism. The axle clamping mechanism includes an expansion slot and a clamping fastener. And the expansion slot includes a neutral position, a compression range, and an expansion range.  
       [0017] When the clamping fastener is moved in a first lateral direction, the clamping fastener compresses the expansion slot to a position in the compression range.  
       [0018] When the clamping fastener is moved in a second lateral direction by a first amount allows, the expansion slot is allowed to expand back to the neutral position. And, any movement thereafter expands the expansion slot to a position in the expansion range.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0019] The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which:  
     [0020]FIG. 1 illustrates a simplified diagram of a go-cart chassis;  
     [0021]FIG. 2 illustrates a simplified diagram of a tubular clamp assembly;  
     [0022] FIGS.  3 A-B illustrate simplified diagrams of an expansion slot;  
     [0023]FIG. 4A illustrates a simplified diagram of a tubular clamp assembly, with the addition of a stopping screw, according to an embodiment of the invention;  
     [0024]FIG. 4B illustrates a simplified diagram of a clamping screw and a stopping screw, according to an embodiment of the invention;  
     [0025] FIGS.  5 A-C illustrate simplified diagrams of the expansion slot according to an embodiment of the invention;  
     [0026]FIG. 6 illustrates a simplified clamping screw with a stopping ring, according to an embodiment of the invention; and,  
     [0027] FIGS.  7 A-C illustrate simplified diagrams of the expansion slot with a clamping screw and stopping ring, according to an embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0028] The present invention will now be described in detail with reference to a few preferred embodiments thereof as illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without some or all of these specific details. In other instances, well known process steps and/or structures have not been described in detail in order to not unnecessarily obscure the present invention. The features and advantages of the present invention may be better understood with reference to the drawings and discussions that follow.  
     [0029] In accordance with one aspect of the invention, a stopping screw is advantageously employed in the clamp assembly to facilitate expansion of the expansion slot. Referring now to FIG. 4A, a simplified tubular clamp assembly  400  is shown with the addition of a stopping screw  410 . The hub of wheel  106 , shown in FIG. 1, is commonly attached to the clamp assembly  400  by a fastener, such as a lug, bolt, or screw, through a hub attachment mechanism, such as flanges  208   a - b.  Axle  104 , also shown in FIG. 1, is commonly inserted through end  204 , sliding into the clamp assembly clamping cavity. The diameter of the clamping cavity is normally 1/1000 th  of an inch larger in size than the diameter of the axle for which it has been designed. Clamp assembly  200  further comprises an expansion slot  206 , which allows the compression of clamp assembly  200  around the axle at the proper position. Normal to expansion slot  206  is a clamping screw  202 . By tightening clamping screw  202 , expansion slot  206  is compressed from a neutral point to a point in its compression range, reducing the diameter of the clamp assembly cavity, and subsequently securing it the around axle  104 .  
     [0030] In order to expand expansion slot  206  to a neutral position, the process is reversed by loosening the clamping screw. However, further expansion may be necessary to accommodate axle expansion, or lodged foreign material in the clamp assembly clamping cavity  204 .  
     [0031] Unlike current hub attachment structures which may necessitate the use of a wedge and hammer in order to become free of the axle, the current invention uses clamping screw  202  itself in combination with stopping screw  410  in order further expand the expansion slot  206  from the neutral point to a point in its expansion range, sufficient to free the clamp assembly from the axle.  
     [0032] In this embodiment, stopping screw  410  is positioned substantially normal to both clamping screw  202  and expansion slot  206 . While expansion slot  206  is at a neutral point, or at a point in the compression range, there is no substantial contact between clamping screw  202  and stopping screw  410 . As expansion slot  206  enters the expansion range through the further loosening of clamping screw  202 , it comes into contact with the head of stopping screw  410 . This restricts further lateral movement of clamping screw  202  toward stopping screw  404 . Further loosening of clamping screw  202  instead causes expansion slot  206  to expand in a lateral direction away from stopping screw  404  and into the expansion slot expansion range. This increases the diameter of the clamp assembly cavity  204 , and subsequently frees it from axle  104 .  
     [0033] Referring now to FIG. 4B, clamping screw  202  and stopping screw  410  of FIG. 4A are shown in greater detail. In this diagram, clamping screw  202  is shown in a position relative to stopping screw  404  corresponding to the neutral point of expansion slot  206 , as shown if FIG. 4A. In this position there is a small gap  412 , allowing clamping screw  202  to freely rotate. Further loosening of clamping screw  202 , will bring it into contact with stopping screw  404 , restricting further lateral movement of clamping screw  202 , and causing expansion slot  206  to expand in a lateral direction away from stopping screw  404  and into the expansion range of the expansion slot. As in FIG. 4A, this would increase the diameter of the clamp assembly cavity  204 , and substantially free it from axle  104 .  
     [0034] Referring now to FIGS.  5 A-C, in accordance with another aspect of the invention, simplified diagrams of the expansion slot  206  are shown. It should be noted that in FIGS.  5 A-C, the relative positions of clamp assembly components, as well as the degree of expansion slot wall bending, are not necessarily drawn to scale.  
     [0035]FIG. 5A illustrates clamping screw  202 , expansion slot  206 , and stopping screw  410 , wherein clamping screw  202  has been tightened to cause expansion slot  206  to be at a point in the compression range. In this position, clamping screw  202  has no substantial contact with stopping screw  41   0 . The walls of expansion slot  206  bend toward each other, compressing the hub attachment structure.  
     [0036]FIG. 5B illustrates clamping screw  202 , expansion slot  206 , and stopping screw  410 , wherein clamping screw  202  is loosened in lateral direction  507 , causing expansion slot  206  to expand to a neutral position. Again, at this position, there is no substantial contact between clamping screw  202  and stopping screw  410 , although any further loosening of clamping screw  202  would cause clamping screw  202  to come into substantial contact with stopping screw  410 . In the neutral position, the walls of expansion slot  206  are substantially parallel.  
     [0037]FIG. 5C illustrates clamping screw  202 , expansion slot  206 , and stopping screw  410 , wherein clamping screw  202  is loosened further to cause expansion slot  206  to be at a point in the expansion range. Clamping screw  202  is restricted from further lateral movement in direction  507 , as shown in FIG. 5B, by contact with stopping screw  410 . Instead further loosening of clamping screw  202  causes expansion slot  206  to expand in a lateral direction  510  away from stopping screw  404  and into the expansion range. This increases the diameter of the clamp assembly cavity  204 , as shown in FIG. 4A, and substantially frees it from axle  104 , as shown in FIG. 1.  
     [0038] In another embodiment of the present invention, a stopping ring is advantageously employed in the clamp assembly to facilitate expansion of the expansion slot. Referring now to FIG. 6, a simplified clamping screw  602  is illustrated, wherein a stopping ring  604  is positioned between the ends of clamping screw  602 , at a point between head  606  and threads  610 . While expansion slot  206 , shown in FIG. 4A, is at a neutral point, or at a point in the compression range, there is no substantial contact between clamping ring  604  and the walls of expansion slot  206 . As clamping screw  602  is further loosened, stopping ring  604  comes into contact with one of the walls of expansion slot  206 , restricting its further lateral movement, and causing expansion to expand into the expansion range.  
     [0039] Referring now to FIGS.  7 A-C, in accordance with another aspect of the invention, simplified diagrams of the expansion slot  206  are shown. It should be noted that in FIGS.  7 A-C, the relative positions of clamp assembly components, as well as the degree of expansion slot wall bending, are not necessarily drawn to scale.  
     [0040]FIG. 7A illustrates clamping screw  702 , expansion slot  206 , and stopping ring  604 , wherein clamping screw  702  has been tightened to cause expansion slot  206  to be at a point in the compression range. In this position, clamping screw  702  has no substantial contact with stopping ring  604 . The walls of expansion slot  206  bend toward each other, compressing the hub attachment structure.  
     [0041]FIG. 7B illustrates clamping screw  702 , expansion slot  206 , and stopping ring  604 , wherein clamping screw  702  is loosened to cause expansion slot  206  to a neutral position in a lateral direction  707 . Again, at this position, there is no substantial contact between clamping screw  702  and stopping ring  604 , although further loosening of clamping screw  702  would cause it to come into contact with stopping ring  604 . The walls of expansion slot  206  are substantially parallel.  
     [0042]FIG. 7C illustrates clamping screw  702 , expansion slot  206 , and stopping ring  604 , wherein clamping screw  702  is loosened further to cause expansion slot  206  to be at a point in the expansion range. Clamping screw  202  is restricted from further lateral movement by the contact of stopping ring  604  the wall of expansion slot  206 . Instead further loosening of clamping screw  702  causes expansion slot  206  to expand in a lateral direction  710  away opposite to the previous lateral direction  707 , of FIG. 7B, and into the expansion range. This increases the diameter of the clamp assembly cavity  204 , as shown in FIG. 4A, and substantially frees it from axle  104 .  
     [0043] While this invention has been described in terms of several preferred embodiments, there are alterations, permutations, and equivalents which fall within the scope of this invention. For example, although the drawings are described in the context of a go-cart, it should be understood that the invention also applies to other hub and axle structures, as well as to non-tubular clamping assemblies. Furthermore, the term screw should be understood to apply to other types of fasteners, such as bolts, clips, and pins. It should also be noted that there are many alternative ways of implementing the apparatuses of the present invention. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations, and equivalents as fall within the true spirit and scope of the present invention.  
     [0044] Advantages of the invention include the ability to loosen a clamp assembly from an axle, in a rapid and safe manner, and with a single tool. Additional advantages of the invention include reducing aesthetic damage to the hub attachment structure, and extending its useful life.  
     [0045] Having disclosed exemplary embodiments and the best mode, modifications and variations may be made to the disclosed embodiments while remaining within the subject and spirit of the invention as defined by the following claims.