Patent Publication Number: US-8986174-B2

Title: Barbell assembly

Description:
BACKGROUND OF INVENTION 
     1. Field of the Invention 
     The invention relates generally to exercise equipment. Specifically, this invention relates to weight-lifting equipment, such as Olympic bars. 
     2. Background Art 
     When one lifts a barbell from the ground to a position above one&#39;s head, the bar rotates 180 degrees. If weight plates do not rotate freely, they would generate a substantial torque that would be transmitted to the lifter&#39;s wrist/skeletal systems. Because the weights lifted by athletes may range from 100-500 lbs or more, such torque transfer not only can be painful, but also can cause an “overuse injury” to the athletes. For safety and comfort, barbells may be equipped with rotating sleeves to allow weight plates to rotate and to make strength training more productive and safer. 
     Olympic barbells (Olympic bars) are specially designed for professional use at Olympic games and other competitive events. Common features of Olympic bar designs include sleeves that can rotate freely and smoothly, while supporting the weight of the plates. This makes it easier for user to practice more “explosive” weight lifting. 
     An Olympic bar for men is about 2.2 m (7.22 ft) long and weighs about 20 kg (44.1 lbs). The outer ends (rotating sleeves) are about 50 mm (1.9685 in) in diameter for accommodating the weight plates, while the grip section is about 28 mm (1.1024 in) in diameter, and 1,310 mm (51.57 in) in length. A women&#39;s Olympic bar is similar to the men&#39;s bar, but is shorter—2.05 m (6.73 ft)—and lighter—15 kg (33.07 lbs)—with a smaller grip section diameter (25 mm). 
     To allow sleeves to rotate freely, Olympic bars typically incorporate bushings, ball bearings, or needle bearings in their rotation mechanisms. Because needle bearings have long, thin bearing elements that have more surface areas than ball bearings, needle bearings can take the weight loads better and are preferred over ball bearings. In addition, bushings are commonly used because of their durability and low maintenance. 
     In addition to the rotation mechanism, the Olympic bars also need to have a retention mechanism that allows the rotating sleeves to stay on a shaft (i.e., without longitudinal sliding), while allowing the rotating sleeves to have free rotation. Common retention mechanisms may include bolts, pins, or snap rings. An example that uses a bolt to secure a rotating sleeve to a handle bar is shown in  FIG. 1 , while an example that uses a roller pin is shown in  FIG. 2 . 
       FIG. 1  shows a cross-sectional view of a bar assembly  10  that uses a bolt to join the rotating sleeves and the shaft, as disclosed in U.S. Pat. No. 6,770,016 issued to Anderson et al. As shown, the bar assembly  10  includes a shaft  14  (a handle bar). A sleeve  12  is slide over the shaft  14 . The sleeve  12  together with an end element  11  are retained on the shaft  14  by a bolt  16 . The bolt  16  is threaded into a female threaded end portion  18  on the shaft  14 . Once the bolt  16  is fixed at the end portion  18  of the shaft  14 , it helps to retain the end element  11  and the sleeve  12  on the shaft  14  and prevent them from sliding off the end of the shaft  14 . 
     To allow rotational freedom of the sleeve  12  around the shaft  14 , the bolt  16  passes through a hole in the end element  11  and is then threaded into the end portion  18  of the shaft  14 . The bolt  16  is inserted inline with the longitudinal axis of the shaft  14  (or the rotational axis of the sleeves  12 ) to allow the sleeve  12  to freely rotate around the shaft  14 . However, sleeve rotation might from time to time exerts rotational force on the bolt  16 . As a result, the bolt  16  may gradually come loose. 
     An alternative to a bolt is to use a roll pin or a snap ring to retain a rotating sleeve on a shaft. With this mechanism, a roll pin or a snap ring is lodged in matched grooves on the shaft and the rotating sleeve to prevent them from sliding in the longitudinal direction, while allowing rotational motions.  FIG. 2  shows an example of a bar assembly  20  that uses a roll pin to retain a rotating sleeve on a handle bar. 
     As shown in  FIG. 2 , a bar assembly  20  includes a roll pin  26  to retain a sleeve  22  on a shaft  24 . The roll pin  26  may be made by rolling a piece of metal in a way that it would exhibit elasticity such that it can be forced into a groove  28 . Once lodged in the groove  28 , the roll pin  26  can expand to lock the sleeve  22  on the shaft  24  to prevent the sleeve  22  from sliding off the end of the shaft  24 . In a similar manner, a snap ring (in a form of an incomplete circle) can also be used (instead of a roller pin) to retain sleeve  22  on the shaft  24 . In order to allow a roller pin  26  (or a snap ring) to fit into the groove  28 , the thickness of the roll pin  26  must be smaller than the width of the groove  28 . As a result, there is small gap (clearance) in the groove/roller pin setup. The gap allows the sleeve  22  to slide longitudinally on the shaft  24 , albeit very slightly. In addition, while the grooves may be only millimeters deep, such grooves would weaken the bars and the sleeves. 
     While these prior art approaches to sleeve retentions on the shafts (e.g., using bolts, pins, and/or snap rings) are satisfactory in most situations, there is still a need for improved mechanisms to secure rotating sleeves on shafts. 
     SUMMARY OF INVENTION 
     One aspect of the invention relates to barbells. A barbell in accordance with one embodiment of the invention comprises a bar assembly that comprises a sleeve rotatably fitted over a rotating-locking mechanism at an end of a shaft; and an end cap attached to an open end of the sleeve to enclose the rotating-locking mechanism and the end of the shaft inside the sleeve, wherein the rotating-locking mechanism comprises a supporting ring rotatably fitted over the shaft and a joining ring attached to the end of the shaft, wherein the supporting ring abuts, on one side, a shoulder on an inner surface of the sleeve and, on the other side, the joining ring. 
     Another aspect of the invention relate to methods for producing barbells. A method in accordance with one embodiment of the invention includes the steps of: fitting a sleeve over an end portion of a shaft, wherein the sleeve comprises a cylindrical bore, an open end, and a should on its inner surface; fitting a supporting ring over the shaft and in the sleeve to abut the shoulder; attaching a joining ring to the end portion of the shaft such that it abuts the supporting ring; and attaching an end cap to the open end of the sleeve to enclose the end portion of the shaft, the supporting ring, and the joining ring inside the sleeve. 
     In some embodiments, the joining ring may be attached to the end of the shaft by thread engagement, and a pin is inserted through an off-center hole in the joining ring and into an off-center hole in the end of the shaft. In some embodiments, the joining ring may be attached to the end of the shaft by interference fit. 
     In any of the above embodiments, the supporting ring comprises a plurality of needle bearings. In any of the above embodiments, the shoulder may be formed by a flange on the inside surface of the sleeve or two bore sections having different diameters inside the sleeve. In any of the above embodiments, the end cap may be attached to the sleeve by thread engagement, interference fit, soldering, or the like. 
     Other aspects and advantages of the invention will be apparent from the following description and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  shows a cross-sectional view of a prior art bar sleeve. 
         FIG. 2  shows a cross-sectional view of another prior art bar sleeve. 
         FIG. 3  shows a cross-sectional view of a bar assembly in accordance with one embodiment of the invention. 
         FIG. 4A  shows a n end view of a shaft in accordance with one embodiment of the invention. 
         FIG. 4B  shows a side view of the shaft of  FIG. 4A . 
         FIG. 5  shows a cross-sectional view of a sleeve in accordance with one embodiment of the invention. 
         FIG. 6A  shows a perspective view of a supporting ring in accordance with one embodiment of the invention. 
         FIG. 6B  shows a perspective view of another supporting ring in accordance with one embodiment of the invention.  FIG. 6C  shows a perspective view of yet another supporting ring in accordance with one embodiment of the invention. 
         FIG. 7A  shows a perspective view of a joining ring in accordance with one embodiment of the invention. 
         FIG. 7B  shows an end view of the joining ring of  FIG. 7A . 
         FIG. 7C  shows a cross-sectional view of the joining ring of  FIG. 7A . 
         FIG. 8A  shows a perspective view of an end cap in accordance with one embodiment of the invention. 
         FIG. 8B  shows a cross-sectional view of the end cap of  FIG. 8A . 
         FIG. 9  shows a method in accordance with an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the invention relate to barbells, such as Olympic bars, and methods for making such barbells. Although the following description use Olympic bars as examples to illustrate embodiments of the invention, one skilled in the art would know that embodiments of the present invention may also include other weight-lifting equipment, such as dumbbells and power-lifting bars. 
     As noted above, rotation mechanisms (such as bushing, ball bearings, and needle bearing) are included on Olympic bars to allow sleeves to rotate freely on the bars. In addition, the rotating sleeves are retained on shafts (handle bars) using a retention mechanism (e.g., bolts, pins, or snap rings) to prevent them from sliding off the ends of the bars. In the prior art Olympic bars, the rotation mechanism and the retention mechanism comprise separate structures. 
     Embodiments of the invention relate to Olympic bars having a novel, combined rotation-retention mechanism, which functions as both a rotation mechanism and a retention mechanism. Such a combined rotation-retention mechanism is based on interworking of several parts described below. The Olympic bars are more secure and more reliable. The following examples illustrate the interworking of the various parts. One skilled in the art would appreciate that these examples are for illustration only, and other modifications and variations are possible without departing from the scope of the invention. 
       FIG. 3  shows a cross-sectional view of an Olympic bar assembly  30  at one end of an Olympic bar in accordance with one embodiment of the invention. A similar bar assembly is disposed at the other end of the bar. 
     As shown in  FIG. 3 , bar assembly  30  in this example includes a sleeve  35  slides over a shaft  34  and covers a supporting ring  36  and a joining ring  38 . An end cap  33  is attached to the distal end of the sleeve  35  to enclose the supporting ring  36  and the joining ring  38  inside the sleeve  35 . The sleeve  35  may freely rotate about the shaft  34  around a longitudinal axis  31  of shaft  34 . 
     The supporting ring  36  may be a cylindrical piece fits over the shaft  34  such that it can freely rotate around the shaft  34 . The proximal end (the end towards the center of the Olympic bar) of the supporting ring  36  abuts a shoulder  53  formed inside the sleeve  35 , while the distal end of the supporting ring  36  abuts the joining ring  38 . The joining ring  38  is fixed to the end  34   a  of the shaft  34 . The joining ring  38  may be fixed to the end  34   a  on the shaft  34  by a thread mechanism or other engagement mechanism (e.g., interference fit). 
     In the embodiment shown in  FIG. 3 , the supporting ring  36  plays dual functions. First, it functions as rotation mechanism (i.e., a bushing) to allow the sleeve  35  to freely rotate around the shaft  34 . In addition, it also functions as a retention mechanism (like a roll pin or snap ring) to prevent the sleeve  35  from sliding in the longitudinal direction on the shaft  34 . 
     To function as a retention mechanism, the supporting ring  36 , at its proximal end  36   a , abuts the shoulder  53  inside the sleeve  35 , and the distal end  36   b  of the supporting ring  36  abuts the joining ring  38 . The joining ring  38  is fixedly attached to the end portion  34   a  of the shaft  34 . As a result, the supporting ring  36  cannot slide off the end of the shaft  34 —because it is stopped by the joining ring  38 . In turn, the supporting ring  36  prevents the sleeve  35  from sliding off the end of the shaft  34  because the sleeve  35 , via is shoulder  53 , bumps into the supporting ring  36 . 
     On the other hand, the sleeve  35  is prevented from sliding further toward the center section of the shaft  34  because the end cap  33 , which caps the distal end of the sleeve  35 , abuts the joining ring  38  and would not be able to move past the joining ring  38 . 
     Thus, by a novel arrangement of these components (the shoulder  53 , the supporting ring  36 , the joining ring  38 , and the end cap  33 ), the sleeve  35  is prevented from sliding on the shaft  34  in the longitudinal direction. In this respect, the supporting ring  36  functions as a part of a retention mechanism to hold the rotating sleeve  35  in place (longitudinally) on the shaft  34 . At the same time, the sleeve  35  (together with the end cap  33 ) is permitted to rotate freely around the shaft  34 , and the supporting ring  36  functions as a bushing in this respect. 
     As noted above, the joining ring  38  may be threaded onto the end portion  34   a  of the shaft  34  or by other mechanisms. If the joining ring  38  is threaded on the end portion  34   a , a pin  37  may be inserted, through an off-centered hole on the joining ring  38 , into a matching off-centered hole  39  on the end portion  34   a  to prevent the joining ring  38  from unintentionally loosening due to rotation. 
     As shown in  FIG. 3 , Olympic bars according to embodiments of the invention rely on a combination of various components (an internal shoulder  53  inside the sleeve, a supporting ring  36 , a joining ring  38 , and an end cap  33 ) to retain the rotating sleeves  35  on the handle bars (shafts  34 ). The use of these separate components avoid the need for coaxial bolts to hold the sleeves in place. Furthermore, these components may be assembled from one end of the bar (the distal end), which allows one to assemble these components without any gap (clearance) commonly found in a roll pin or snap ring retention mechanism. The individual components and their assembly will be described in more detail in the following sections. 
     A handle bar of embodiments of the invention may be configured to attach with the joining ring  38  in any suitable manner that can securely hold the joining ring  38  in place. One such attachment mechanism may be by thread engagement. For example,  FIG. 4(A)  and  FIG. 4(B)  show an end view and a side view, respectively, of an end section  34   a  of a shaft  34 . The end section  34   a  in this example is configured with a screw thread  33   a  for attachment of a joining ring  38  by a thread engagement. A thread engagement may come loose over time due to various forces causing relative rotation the parts. To prevent unintentional loosening of the joining ring  38 , an off-center hole  39  may be provided on the end portion  34   a  for insertion of a pin  37 . While this example shows a male thread on the end portion  34   a  for mating with a female thread on the joining ring  38 , the reverse arrangement may also be used. Furthermore, while a thread engagement is shown in this example, other attachment means may also be used, such as a compression fit. 
     In preferred embodiments, a joining ring is configured to be attached to the end portion of a bar by thread engagement, as shown in  FIGS. 7A and 7C , which shows a perspective view and a front cross-sectional view of a joining ring  38 , respectively. The joining ring  38  may have an open end  38   a  and a closed end  38   b  opposing to open end  38   a . The internal surface  76  of the joining ring  38  may be configured to attach to the end portion  34   a  of shaft  34  by threaded engagement with the thread  33   a  on the end portion  34   a  (see  FIG. 4B ). Other configurations of internal surface  76 , which allow joining ring  38  to be fastened to the end portion  34   a , may be used, such as compression fit. When the joining ring  38  is securely fastened to the end portion  34   a , its open end  38   a  would abut the distal end  36   b  of the supporting ring  36 . 
     As noted above, when the joining ring  38  is threaded on the end portion  34   a , the threaded engagement may become loosened due to free rotation of the sleeve  35 . To eliminate this possibility, a pin  37  may be inserted through the joining ring  38  into the off-center hole  39  on the end portion  34   a  ( FIG. 4A ).  FIG. 7B  shows an end view from the open end  38   a , illustrating an off-center hole  78 , which matches the off-center hole  39  on the end portion  34   a  when the joining ring  38  is attached to the end portion  34   a.    
     The joining ring  38  shown in the example of  FIG. 3  and  FIG. 7  has a cup shape to fit over an end of a shaft to provide a flange to abut the distal end of a supporting ring. One of ordinary skilled in the art would appreciate that other shapes of a joining ring may also be used as long as it can be fixed to the end of a shaft to provide a flange to abut the supporting ring. For example, a joining ring may be a simple plate/disc for attachment to the end of a shaft to provide a flange; the attachment may be by any suitable means, e.g., screws or bolts. 
     As in any Olympic bar, a rotating sleeve is used to hold the weight plates on the bar while allowing for rotation. In accordance with embodiments of the invention, a rotating sleeve is configured to provide a shoulder to abut a supporting ring. The shoulder inside a sleeve may be provided by a flange (a ring of protrusion on the inside surface of the sleeve) or by different internal bores with different diameters.  FIG. 5  shows a schematic of an example having different internal bores with different diameters. 
     As shown in  FIG. 5 , a sleeve  35  has a first bore section  51  with an inside diameter d 1  configured to fit over the shaft  34  and a second bore section  55 , which has a slightly larger diameter d 2 , such that a shoulder  53  is formed at the junction of the first bore section  51  and the second bore section  55   a . The first bore section  51  is closer to the proximal end  50 , while the second bore section  55  is closer to the distal end  54 . The outer diameter of the sleeve  35  is sized to accommodate the center holes of weight plates/discs (not shown). 
     The inside diameter d 2  of the second bore section  55  is sized to accommodate an assembly that includes the shaft  34 , the supporting ring  36 , and the joining ring  38  (see  FIG. 3 ). The shoulder  53  is configured to abut the proximal end  36   a  of the supporting ring  36  (see  FIG. 3 ). In this example, the shoulder  53  is formed by two bore sections  51  and  55  having different diameters. As noted above, in other examples, the shoulder  53  may be formed by a flange, while the first bore section  51  and the second bore section  55  may have the same diameter. 
     The sleeve  35  has an end section  58  for attaching an end cap  33 . The internal surface of the third end section  58  may be configured with a female thread for attachment of the end cap  33 , which has a matching male thread, by thread engagement. While this example shows that the end cap  33  fits inside the distal end  54  of the sleeve  35 , one may also have the end cap  33  configured to fit on the outside of the distal end  54 . Furthermore, in addition to thread engagement, the end cap  33  may also be configured to attach to the distal end  54  by other means, such as a compression fit or soldering. 
     The function of the end cap  33  is to enclose the rotation-retention mechanism inside the sleeve  35  and also to prevent the sleeve  35  from sliding towards the center of the Olympic bar.  FIGS. 8A and 8B  show a perspective view and a cross-sectional view of an end cap  33 , respectively, in accordance with one embodiment of the invention. The end cap  33  has a proximal end  80  and a closed end  84 . At least a part of the external surface  86  of the end cap  33  is configured for attachment to the distal end  54  of sleeve  35 . Any configurations of the external surface  86  suitable for secure attachment to the sleeve  35  may be used. Some embodiments of the invention may include an end cap  33  with an externally threaded surface  86  configured to be threaded into an internally threaded surface of the end section  58  of the sleeve  35 , as noted above. While this example shows that the end cap  33  is attached to the inside of the sleeve  35 , in an alternative embodiment, the end cap  33  may be attached to the outside of the sleeve  35 . Furthermore, the end cap  33  may be attached to the sleeve  35  by other mechanisms, such as interference fit, soldering, or similar methods. 
     As noted above, a supporting ring  36  in accordance with embodiments of the invention may have a dual function—as part of a rotation mechanism and as part of a retention mechanism.  FIG. 6A  shows a perspective view of a supporting ring  36 , which is an annular bushing, includes a proximal end  36   a  and a distal end  36   b . The supporting ring  36  is configured to fit over the shaft  34  and is disposed in the second bore section  55  of the sleeve  35  such that its proximal end  36   a  abuts the shoulder  53 . The supporting ring  36  may reinforce the strength of the sleeve  35  and the shaft  34  when weight plates are loaded. In this example, the supporting ring  36  is a bushing, having a structure of a simple tubular section. In other examples, the supporting ring  36  may further comprise roller pins (i.e., needle bearings), as shown in  FIG. 6B , which shows a supporting ring  60  having a plurality of needle bearing  61 . Similarly, one may have ball bearings, instead of needle bearings, in a configuration similar to that of supporting ring  60 . For example,  FIG. 6C  shows an embodiment of a supporting ring  60 ′ having a plurality of ball bearings  61 ′. 
     While only one supporting ring  36  is shown in the example in  FIG. 3 , other embodiments of the invention may include two or more supporting rings  36 . In addition, embodiments of the invention may further include other rotation mechanisms, such as bushings, ball bearings, and needle bearings, or a combination thereof. 
     Some embodiments of the invention relate to methods for making a barbell, such as an Olympic bar.  FIG. 9  shows a method  90 , which may include steps of providing a sleeve having a cylindrical bore, wherein the sleeve includes an internal shoulder (step  91 ); disposing a supporting ring inside the sleeve such that a proximal end of the supporting ring abuts the shoulder (step  92 ); inserting an end portion of the shaft into the sleeve and the supporting ring (step  93 ); fastening a joining ring to the end portion of the shaft such that it abuts the supporting ring (step  94 ); and fastening an end cap to cap the distal end opening of the sleeve (step  95 ). The above-described method is for illustration only and other variations and modifications to this method are possible without departing from the scope of the invention. For example, the steps need not be performed in the order described, and one may insert the shaft into the sleeve before sliding the supporting ring onto the shaft. 
     The above description illustrates various embodiments of the invention. One skilled in the art would appreciate that these examples are for illustration only, and other modifications are possible without departing from the scope of the invention. 
     Advantages of embodiments of the invention may include one or more of the following. Olympic bar assemblies of the invention may allow for more secure bars due to the interworking of parts, e.g., supporting rings, joining rings, pins, and end caps. Embodiments of the invention include Olympic bar assemblies do not use coaxial bolts to retain the rotating sleeves on the shafts. Therefore, the risk for parts to be loosening may be reduced. In addition, because sleeve rotation may become smoother, squeaking noises may be reduced. Moreover, embodiments of the invention include Olympic bar assemblies that do not use roll pins and snap rings to secure shaft to sleeve, eliminating any gaps between roll pin and snap ring inserts and grooves. Therefore, there will not be sliding motion of sleeves. 
     While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.