Patent Abstract:
A bicycle crank arm apparatus includes an axle having a first end portion and a second end portion, wherein the first end portion has an outer peripheral surface and a threaded inner peripheral surface; an axle bolt having a threaded outer peripheral surface screwed into the threaded inner peripheral surface of the first end portion of the axle; a crank arm having an axle mounting boss defining an opening for receiving the first end portion of the axle therein, wherein the axle mounting boss includes a first fastener for tightening the crank arm mounting boss around the first end portion of the axle; and wherein the crank arm boss is positioned axially inwardly of the axle bolt.

Full Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation-in-part of copending U.S. patent application Ser. No. 10/002,256 filed Nov. 23, 2001 titled “Seal Assembly for a Bicycle Bottom Bracket.” 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention is directed to bicycles and, more particularly, to a bicycle crank assembly and to the components and tools used to assemble the bicycle crank assembly.  
           [0003]    A bicycle bottom bracket is a cylindrical tube portion of the bicycle frame used to rotatably mount the pedal assembly to the bicycle. The pedal assembly usually comprises right and left crank arms, each of which has a pedal attached to one end. The other end of each crank arm is attached to an axle that extends through the bottom bracket. A bearing assembly is disposed between the axle and the bottom bracket at each side of the bottom bracket for rotatably supporting the axle, and one or more front sprockets usually are attached to the right side crank arm for driving the bicycle chain.  
           [0004]    The front sprocket(s) must be properly aligned with the rear sprocket(s) attached to the rear wheel so that the bicycle operates properly. Thus, the axle must be properly positioned laterally within the bottom bracket. In one known technique for adjusting the lateral position of the axle, the axle is rotatably centered and laterally fixed within a tubular member by bearing assemblies installed at opposite ends of the tubular member. The axle and tubular member then are placed inside the bottom bracket. Adapter members having threaded outer peripheral surfaces are screwed into the threaded inner peripheral surface of the bottom bracket on opposite sides of the tubular member so that the lateral position of the axle is determined by how much of each adapter member is screwed into the bottom bracket. Unfortunately, since the adapter members must be long enough to accommodate many different lateral positions of the axle, usually a portion of the threaded outer peripheral surface of each adapter member is exposed, and this often results in rusting and dirt contamination of the threads. Also, since the axle is fixed to the tubular member through the bearing assemblies, the axle, tubular member and bearing assemblies ordinarily must be replaced as a unit.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention is directed to a bicycle crank assembly wherein the lateral position of the axle may be adjusted without one or more of the disadvantages of prior art axle assemblies. In one embodiment of the present invention, a bicycle crank arm apparatus includes an axle having a first end portion and a second end portion, wherein the first end portion has an outer peripheral surface and a threaded inner peripheral surface; an axle bolt having a threaded outer peripheral surface screwed into the threaded inner peripheral surface of the first end portion of the axle; a crank arm having an axle mounting boss defining an opening for receiving the first end portion of the axle therein, wherein the axle mounting boss includes a first fastener for tightening the crank arm mounting boss around the first end portion of the axle; and wherein the crank arm boss is positioned axially inwardly of the axle bolt. At least one advantage of this structure is that the axle bolt may be used to laterally position the axle and the crank arms relative to each other, and the crank arm may be used to cover any threaded portion of the axle bolt that is not screwed into the axle.  
           [0006]    In one embodiment of an axle bolt used to assembly the crank arm to the axle, an axle bolt includes a bolt body having a threaded outer peripheral surface and an inner peripheral surface defining an opening. A plurality of splines are circumferentially disposed on the inner peripheral surface of the bolt body, and a flange extends radially outwardly from the bolt body.  
           [0007]    In one embodiment of a tool for screwing the axle bolt into the axle, the tool comprises a tool body, a plurality of splines circumferentially disposed on an outer peripheral surface of the tool body, and a tool operating member extending radially outwardly from the tool body. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is a side view of a bicycle that includes a particular embodiment of a crank assembly according to the present invention;  
         [0009]    [0009]FIG. 2 is a rear cross-sectional view of a particular embodiment of a crank assembly according to the present invention;  
         [0010]    [0010]FIG. 3 is an exploded view of the crank assembly shown in FIG. 2;  
         [0011]    [0011]FIG. 4 is a more detailed view of the crank assembly shown in FIG. 2;  
         [0012]    [0012]FIG. 5 is a cross sectional view of an alternative embodiment of the bushing shown in FIG. 4;  
         [0013]    [0013]FIG. 6 is an oblique view of a particular embodiment of a left side crank arm according to the present invention;  
         [0014]    [0014]FIG. 7 is an outer view of the crank arm shown in FIG. 6;  
         [0015]    [0015]FIG. 8 is an oblique view of particular embodiments of an axle bolt and a tool for mounting the axle bolt to the axle;  
         [0016]    [0016]FIG. 9 is a side view of the axle bolt shown in FIG. 8; and  
         [0017]    [0017]FIG. 10 is a side view of the tool shown in FIG. 8. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0018]    [0018]FIG. 1 is a side view of a bicycle  10  that incorporates a particular embodiment of a crank assembly according to the present invention. Bicycle  10  may be any type of bicycle, and in this embodiment bicycle  10  includes a typical frame  18  comprising a top tube  22 , a head tube  24 , a down tube  26  extending downwardly from head tube  24 , a seat tube  30  supporting a seat  32  and extending downwardly from top tube  22 , a bottom bracket  33  (FIG. 3) disposed at the junction of down tube  26  and seat tube  30 , a pair of seatstays  34  extending rearwardly and downwardly from top tube  22 , and a pair of chainstays  38  extending rearwardly from bottom bracket  33 . A fork  42  is rotatably supported within head tube  24 , and a front wheel  46  is rotatably supported to the lower end of fork  42 . Handlebars  50  control the rotational direction of fork  42  and front wheel  46  in a well-known manner. A rear wheel  54  having a plurality of coaxially mounted rear (freewheel) sprockets  56  is rotatably supported at the junction of seatstays  34  and chainstays  38 , and a pedal assembly  58  supporting a plurality of front (chainwheel) sprockets  62  is rotatably supported within bottom bracket  33 . Pedal assembly  58  includes an axle  59 , a right side crank arm  60 A attached to the right end of axle  59 , a left side crank arm  60 B attached to the left end of axle  59 , and pedals  61 A and  61 B rotatably attached to the ends of crank arms  60 A and  60 B, respectively. Typically, two or three front sprockets  62  rotate coaxially and integrally with right side crank arm  60 A. A chain  66  engages one of the plurality of front sprockets  62  and one of the plurality of rear sprockets  56 . A front derailleur  70  moves chain  66  from one front sprocket  62  to another, and a rear derailleur  74  moves chain  66  from one rear sprocket  56  to another in accordance with shift commands from a rider in a known manner.  
         [0019]    [0019]FIG. 2 is a rear cross-sectional view of a particular embodiment of a bottom bracket assembly  100  according to the present invention, and FIG. 3 is an exploded view of bottom bracket assembly  100 . As shown in those figures, bottom bracket assembly  100  comprises bottom bracket  33 , a dust tube  104  disposed within bottom bracket  33 , wherein dust tube  104  includes annular grooves  108  and  112  at the opposite ends thereof, O-ring seals  116  and  120  fitted within annular grooves  108  and  112 , respectively, and adapter assemblies  124 A and  124 B fitted to the ends of bottom bracket  33  and dust tube  104 . Adapter assemblies  124 A and  124 B are used in part to position axle  59  laterally within bottom bracket  33  so that front sprockets  62  are properly aligned with rear sprockets  56 . Such positioning allows front and rear derailleurs  70  and  74  to operate chain  66  in a satisfactory manner.  
         [0020]    As shown more clearly in FIGS. 3 and 4, in this embodiment adapter assembly  124 A comprises an adapter member  130 A, a bearing ring  134 A, a bearing unit  138 A, a seal ring  142 A, a seal guard  146 A, an O-ring  150 A, two ring-shaped spacers  154 A, and two soft urethane ring-shaped spacer covers  158 A that fit around the outer peripheral surfaces of spacers  154 A as shown in FIG. 2. Similarly, as shown in FIG. 3, adapter assembly  124 B comprises an adapter member  130 B, a bushing in the form of a bearing ring  134 B, a bearing unit  138 B, a seal ring  142 B, a seal guard  146 B, an O-ring  150 B, one ring-shaped spacer  154 B, and a soft urethane ring-shaped spacer cover  158 B that fits around the outer peripheral surface of spacers  154 B. Spacers  154 A and  154 B help to set the lateral position of axle  59  as shown in FIG. 2. In this embodiment there are two spacers  154 A on the right side of bottom bracket assembly  100  and only one spacer on the left side of bottom bracket assembly  100 . Thus, axle  59 , crank arms  60 A and  60 B and sprockets  62  are shifted slightly to the right relative to bottom bracket  33 .  
         [0021]    The adapter assemblies  124 A and  124 B are constructed the same except for the number of spacers, and they operate in the same manner, so only the details of the components of adapter assembly  124 A will be described in detail. As shown more clearly in FIG. 4, adapter member  130 A comprises a smaller diameter tubular portion  162 A having a threaded outer peripheral surface  166 A and a thickened inner portion  170 A, a radially outwardly extending side wall  174 A, and a larger diameter portion  178 A having an inner peripheral surface  182 A and an outer peripheral surface  186 A forming a tool engaging surface  190 A. When adapter assembly  124 A is in the assembled state, threaded outer peripheral surface  166 A of smaller diameter portion  162 A completely screws into a threaded inner peripheral surface  194 A (FIG. 3) of bottom bracket  33  until side wall  174 A of adapter member  130 A abuts against a side edge  198 A of bottom bracket  33  as shown in FIG. 2. Thus, in this embodiment there are no exposed portions of the threaded outer peripheral surface  166 A.  
         [0022]    Bearing ring  134 A comprises a tubular portion  200 A and a radially outwardly extending side wall  204 A. When adapter assembly  124 A is in the assembled state, bearing ring  134 A contacts the inner peripheral surface  182 A of larger diameter portion  178 A of adapter member  130 A, and side wall  204 A abuts against an abutment  208 A formed on inner peripheral surface  182 A. In this embodiment, bearing ring  134 A is formed of a nonmetallic material such as POM plastic.  
         [0023]    In this embodiment, bearing unit  138 A is a conventional sealed bearing unit comprising an inner bearing race  212 A, an outer bearing race  216 A, a plurality of ball bearings  220 A disposed between inner bearing race  212 A and outer bearing race  216 A, and annular side covers  224 A. When adapter assembly  124 A is in the assembled state, outer race  216 A contacts bearing ring  134 A. Since bearing ring  134 A is formed of a nonmetallic material, squeaking and other undesirable noises caused by the contact between these two components are minimized or eliminated. Of course, bearing ring  134 A could be formed of any material that suits the application or for cost reasons.  
         [0024]    Seal guard  146 A functions as a support for seal ring  142 A and O-ring  150 A, and it comprises an annular base member  230 A, an inner tubular member  234 A and an outer tubular member  238 A. In this embodiment, seal guard  146 A is formed of a nonmetallic material such as POM plastic. Inner tubular member  234 A extends from a radially inner side surface of base member  230 A and, in this embodiment, extends from a radially innermost edge  242 A of base member  230 A to form a radially inner peripheral surface or inner ledge  246 A. When adapter assembly  124 A is in the assembled state, inner ledge  246 A contacts and supports inner bearing race  212 A of bearing unit  138 A. A protuberance  248 A extends radially outwardly (approx. 0.1 mm in this embodiment) from the free edge  249 A of inner tubular member  234 A to lock bearing unit  138 A in position on inner tubular member  234 A. Since seal guard  146 A is formed of a nonmetallic material, squeaking and other undesirable noises caused by the contact between these two components are minimized or eliminated. Of course, seal guard  146 A could be formed of any material that suits the application or for cost reasons.  
         [0025]    Outer tubular member  238 A extends from a radially outer side surface of base member  230 A and, in this embodiment, is spaced apart from a radially outermost edge  250 A of base member  230 A to form a radially outer peripheral surface or outer ledge  254 A. When adapter assembly  124 A is in the assembled state, outer ledge  254 A contacts and supports seal ring  142 A and the outer bearing race  216 A of bearing unit  138 A. Thus, bearing unit  138 A is sandwiched between inner ledge  246 A and outer ledge  254 A. While inner tubular member  234 A and outer tubular member  238 A extend from the same side of base member  230 A in this embodiment, it is not necessary for them to do so.  
         [0026]    In this embodiment, seal ring  142 A functions as an outer seal, and it is a generally L-shaped ring member having a base portion  258 A and a radially outwardly extending lip portion  262 A that forms an acute angle with base portion  258 A. Base portion  258 A contacts and is supported by outer ledge  254 A, and lip portion  262 A contacts the inner peripheral surface  128 A of adapter member  130 A. Of course, seal ring  142 A may take many different forms, and there need not be direct contact between the components. O-ring  150 A functions as an inner seal, and it is disposed at the radially inner edge  242 A of base member  230 A opposite inner tubular member  234 A. When adapter assembly  124 A is in the assembled state, O-ring  150 A contacts axle  59 . Seal ring  142 A and O-ring  150 A in combination prevent contaminants from entering the space containing bearing unit  138 A more advantageously than prior art sealing structures.  
         [0027]    [0027]FIG. 5 is a detailed cross sectional view of a bearing ring  134 A′ that represents an alternative embodiment of the bearing ring  134 A shown in FIG. 4. As with bearing ring  134 A, bearing ring  134 A′ comprises a tubular portion  200 A′ and a radially outwardly extending side wall  204 A′. However, in this embodiment a centrally disposed bushing protuberance  260 A extends radially inwardly from tubular portion  200 A for contacting outer bearing race  216 A when adapter assembly  124 A is in the assembled state. If bearing unit  138 A is tilted for some reason as shown by the broken lines in FIG. 5, such as if bottom bracket  33  is bent as a result of a manufacturing defect or a collision, then bushing protuberance  260 A accommodates such tilting. Although bushing protuberance  260 A has a trapezoidal shape in this embodiment, it could have a spherical or other shape to perform the same function  
         [0028]    As shown in FIG. 3, right side crank arm  60 A comprises a crank arm body  300 , an axle mounting boss  304  having an axle mounting opening  308  with a splined inner peripheral surface  312 , a pedal mounting boss  316  having a pedal mounting opening  320  with a threaded inner peripheral surface  324 , and four sprocket mounting arms  328  extending radially outwardly from axle mounting boss  304 . In this embodiment, each sprocket mounting arm  328  has three sprocket mounting openings  328 A,  328 B and  328 C for mounting three front sprockets.  
         [0029]    As shown in FIGS. 6 and 7, left side crank arm  60 B comprises a crank arm body  330 , an axle mounting boss  331  having an axle mounting opening  332  with a splined inner peripheral surface  333 , and a pedal mounting boss  334  having a pedal mounting opening  335  with a threaded inner peripheral surface  336 . In this embodiment, axle mounting boss  311  includes a first mounting ear  337  spaced apart from but in close proximity to a second mounting ear  338 . First mounting ear  337  includes an unthreaded fastener opening  339  and a threaded fastener opening  340 , and second mounting ear  338  includes an unthreaded fastener opening  341  and a threaded fastener opening  342 . A crank arm bolt  343  having a threaded shank  344  and a head  345  extends through unthreaded fastener opening  339  in first mounting ear  337  and screws into threaded opening  342  in second mounting ear  338  such that head  345  abuts against first mounting ear  337 . Similarly, a crank arm bolt  346  having a threaded shank  347  and a head  348  extends through unthreaded fastener opening  341  in second mounting ear  338  and screws into threaded opening  340  in first mounting ear  337  such that head  348  abuts against second mounting ear  338 . Crank arm bolts  343  and  346  thus tighten first mounting ear  337  and second mounting ear  338  towards each other for clamping axle mounting boss  331  around axle  59  as discussed below.  
         [0030]    Axle  59  has an axle body  348  including a first end portion  350  and a second end portion  354 . First end portion  350  has a plurality of circumferentially disposed splines  358  that protrude radially outwardly relative to an outer peripheral surface  362  of axle body  348  for engaging the splined inner peripheral surface  312  of axle mounting boss  308  of crank arm  60 A as shown in FIG. 2. A radially outwardly extending flange  366  is disposed at the extreme end of end portion  350  for abutting against the laterally outer surface of axle mounting boss  308  of crank arm  60 A. Second end portion  354  of axle  59  has a threaded inner peripheral surface  368  (FIG. 2) and a plurality of circumferentially disposed splines  370  for engaging the splined inner peripheral surface  333  of axle mounting boss  331  of crank arm  60 B. In this embodiment, splines  370  do not extend radially outwardly relative to the outer peripheral surface  362  of axle body  348 . Instead, the splines  370  are flush with the outer peripheral surface of  362  of axle body  348 . Second end portion  354  and axle body  348  thus are capable of freely passing through opening  308  in crank axle mounting boss  304  of crank arm  60 A and though dust tube  104  and adapter assemblies  124 A and  124 B so that second end portion  354  of axle  59  extends into opening  332  in crank axle mounting boss  331  of crank arm  60 B and flange  366  abuts against mounting boss  304  of crank arm  60 A.  
         [0031]    An axle bolt  380  screws into the threaded inner peripheral surface  368  of second end portion  354  of axle  59 . As shown in FIGS. 2, 3,  8  and  9 , axle bolt  380  comprises a bolt body  384  having a threaded outer peripheral surface  388  and an inner peripheral surface  392  defining an opening  396 . A plurality of (e.g., eight) splines  400  are circumferentially disposed on the inner peripheral surface  392  of an end  402  of bolt body  384 , and a flange  404  with a knurled outer peripheral surface  408  extends radially outwardly from end  402  of bolt body  384 . In this embodiment, each spline  400  comprises an arcuate projection  412  adjacent to a groove  416 .  
         [0032]    A tool  450  shown in FIGS. 8 and 10 is provided for screwing axle bolt  380  into the threaded inner peripheral surface  368  of second end portion  354  of axle  59 . Tool  450  comprises a tool body  454  and a tool operating member  460 . Tool body  454  comprises a splined portion  458  and a stepped portion  459  disposed between splined portion  458  and tool operating member  460 , wherein stepped portion  459  extends radially outwardly from splined portion  458 . Splined portion  458  comprises a plurality of (e.g., eight) circumferentially disposed splines, each comprising a radially outwardly extending spline projection  459  adjacent to a spline groove  460 . Tool operating member  460  extends radially outwardly from stepped portion  459  of tool body  454 . In this embodiment, tool operating member  460  has a disk shape, and tool body  454  extends from a side surface  470  of tool operating member  460 . A gripping rim  474  having a knurled outer peripheral surface  478  is disposed at a radially outermost portion of tool operating member  460  such that gripping rim  474  extends laterally from a side surface  478  of tool operating member  460 .  
         [0033]    To assemble axle  59  to bottom bracket  33 , dust tube  104 , O-ring seals  116  and  120  and adapter assemblies  124 A and  124 B are mounted to bottom bracket  33 . Axle  59  is passed through opening  308  in crank axle mounting boss  304  of crank arm  60 A and though adapter assemblies  124 A and  124 B and dust tube  104  so that second end portion  354  of axle  59  extends into opening  332  in crank axle mounting boss  331  of crank arm  60 B and flange  366  abuts against mounting boss  304  of crank arm  60 A. Axle bolt  380  is then screwed into the threaded inner peripheral surface  368  of axle  59  using tool  450  by engaging splined portion  458  of tool  450  with splines  400  of axle bolt  380  and by gripping and turning gripping rim  474  until the desired amount of play exists between crank arms  60 A and  60 B and spacers  154 A and  154 B. Thereafter, bolts  343  and  346  are tightened while axle mounting boss  331  of crank arm  60 B abuts against flange  404  of axle bolt  380  to set the final position of crank arm  60 B and thereby the play between crank arms  60 A and  60 B and spacers  154 A and  154 B.  
         [0034]    While the above is a description of various embodiments of the present invention, further modifications may be employed without departing from the spirit and scope of the present invention. For example, the size, shape, location or orientation of the various components may be changed as desired. Components that are shown directly connected or contacting each other may have intermediate structures disposed between them. The functions of one element may be performed by two, and vice versa. It is not necessary for all advantages to be present in a particular embodiment at the same time. Every feature which is unique from the prior art, alone or in combination with other features, also should be considered a separate description of further inventions by the applicant, including the structural and/or functional concepts embodied by such feature(s). Thus, the scope of the invention should not be limited by the specific structures disclosed or the apparent initial focus on a particular structure or feature.

Technology Classification (CPC): 5