Bottom bracket assembly

Abstract: A bottom bracket assembly includes a first bowl (31) and a second bowl (32) each having an outer thread (312 and 322) engaged in an inner thread of a bottom bracket (30) respectively. An axle (10) is mounted in a tube (20) which includes a first end having an outer thread (202) engaged in an inner thread (314) of the first bowl (31) and a second end having a tapered surface (204) urging on a tapered surface (324) of the second bowl (32). A ball bearing (42) is mounted between an annular recess (310) of the first bowl (31) and an annular recess (11) of the axle (10). A ball bearing (41) is mounted between an annular recess (21) of the tube (20) and an annular recess (12) of the axle (10).

Description: The present invention relates to a bottom bracket assembly. GB-A-2166810 shows a pedal crank bearing for bicycles where a tubular piece is inserted into an annular space defined by the external frame sleeve of the cranck bearing and by an housing part positioned inside the frame sleeve so as to fix the housing part in the frame sleeve, specifically in the radial direction. Formed on the tubular piece there is a flange which projects radially outwards and which is laid against the end face of the frame sleeve, thereby limiting the depth of the insertion of the tubular piece. By such an arrangement, the tubular piece simply exerts a radial force on the housing part and cannot exert an axial force on said housing part synchronously, such that the engagement between the housing part and the tubular piece is not snugly arranged and such that the tubular piece easily becomes loosened from the housing part during long-term utilization. A conventional bottom bracket assembly is shown in Fig. 2. However, by such an arrangement, there are still some shortcomings in the conventional bottom bracket assembly. Referring to Fig. 2, a conventional bottom bracket assembly in accordance with the prior art comprises a bottom bracket 80 including a first end portion and a second end portion each having an inner threaded portion (not labeled) formed along an inner periphery thereof. A tube 81 is mounted in the bottom bracket 80 and includes a first end having an outer threaded portion 812 formed along an outer periphery thereof for engagement in the inner threaded portion of the first end portion of the bottom bracket 80, and a second end having a tapered surface 814 formed along an outer periphery thereof. A first annular recess 85 and a second annular recess 84 are respectively defined in an inner periphery of the first and second ends of the tube 81. A bowl member 86 includes an outer threaded portion 862 formed along an outer periphery thereof for engagement in the inner threaded portion of the second end portion of the bottom bracket 80. A tapered surface 864 is formed along an inner periphery thereof for urging on the tapered surface 814 of the tube 81. An axle 90 is rotatably mounted in the tube 81 and includes a first end portion having an outer threaded portion 93 formed along an outer periphery thereof, and a second end portion having third annular recess 91 defined in an outer periphery thereof. A race 92 is threadedly mounted around the outer threaded portion 93 of the axle 90 and has a fourth annular recess 922 defined in an outer periphery thereof. A nut 95 is threadedly mounted around the outer treaded portion 93 of the axle 90 for urging on the race 92 and a washer 94 is mounted therebetween. A first ball bearing 83 is rotatably mounted between the first annular recess 85 of the tube 81 and the fourth annular recess 922 of the race 92 and a second ball bearing 82 is rotatably mounted between the second annular recess 84 of the tube 81 and the third annular recess 91 of the axle 90. Preferably, a first waterproof gasket 97 is mounted around the nut 95 and engaged in the first end of the tube 81, and a second waterproof gasket 96 is mounted around the second end portion of the axle 90 and engaged in the second end of the tube 81. By such an arrangement, the first and second ball bearings 83 and 82 have to be respectively urged by the race 92 and the bowl member 86 synchronously such that a force exerted on the first ball bearing 83 by the race 92 must be equal to that exerted on the second ball bearing 82 by the bowl member 86, thereby accomplishing a structural coupling stably. If the two forces are not balanced, the ball bearings 83 and 82 are easily worn out, so greatly causing time-consuming adjustment of the forces exerted by the race 92 and the bowl member 86 respectively on the first and second ball bearings 83 and 82. In addition, the bottom bracket assembly requires a lot of parts for assembling, so causing a great cost in manufacturing. In accordance with the present invention the above problems are solved by the features of claim 1. Accordingly, by such an arrangement, the first flange portion of the first bowl member is abutted against the second flange portion of the tube and the tapered surface of the second bowl member is securely urged on the tapered surface of the tube so as to exert a radial and axial force on the tube, which is subsequently transmitted to the axle, thereby easily positioning the axle in the bottom bracket. In the drawings: Fig. 1 is a front plan partially cross-sectional view of a bottom bracket assembly in accordance with the present invention; and Fig. 2 (as disclosed above) is a front plan partially cross-sectional view of a conventional bottom bracket assembly in accordance with the prior art. Referring to Fig. 1, a bottom bracket assembly in accordance with the present invention comprises a bottom bracket 30 including afirst end portion and a second end portion each having a threaded portion (not labeled) formed along an inner periphery thereof. A first bowl member 31 has a first outer threaded portion 312 formed along an outer periphery thereof for engagement in the threaded portion of the first end portion of the bottom bracket 30. An inner threaded portion 314 is formed along an inner periphery of the first bowl member 31. A first annular recess 310 is defined in the inner periphery of the first bowl member 31, and a first flange portion 316 is formed on a distal end of the first bowl member 31. A second bowl member 32 has a second outer threaded portion 322 formed along an outer periphery thereof for engagement in the threaded portion of the second end portion of the bottom bracket 30, and a first tapered surface 324 is formed along an inner periphery of the second bowl member 32. A tube 20 is fixedly mounted in the bottom bracket 30 and comprises a first end having a third outer threaded portion 202 formed along an outer periphery thereof for engagement in the inner threaded portion 314 of the first bowl member 31 and a second end having a second tapered surface 204 formed along an outer periphery thereof for urging on the first tapered surface 324 of the second bowl member 32. A second annular recess 21 is defined in an inner periphery of the second end of the tube 20. A second flange portion 22 is formed on the first end of the tube 20 for abutting against the first flange portion 316 of the first bowl member 31. An axle 10 is rotatably mounted in the tube 20 and comprises a first end portion having a third annular recess 11 defined in an outer periphery thereof and a second end portion having a fourth annular recess 12 defined in an outer periphery thereof. A first ball bearing 42 is rotatably mounted between the first annular recess 310 of the first bowl member 31 and the third annular recess 11 of the axle 10, and a second ball bearing 41 is rotatably mounted between the second annular recess 21 of the tube 20 and the fourth annular recess 12 of the axle 10. Preferably, the bottom bracket assembly further comprises a first washer 44 mounted around the first end portion of the axle 10 and engaged in the first bowl member 31 for water-proofing purposes, and comprises a second washer 43 mounted around the second end portion of the axle 10 and engaged in the second end of the tube 20 for water-proofing purposes.

Claims: A bottom bracket assembly comprising: a bottom bracket (30) comprising a first end portion and a second end portion, each having a threaded portion formed along an inner periphery thereof; a first bowl member (31) having a first outer threaded portion (312) formed along an outer periphery thereof for engagement in said threaded portion of said first end portion of said bottom bracket (30) and a first annular recess (310) defined in the inner periphery of said first bowl member (31); a second bowl member (32) having a second outer threaded portion (322) formed along an outer periphery thereof for engagement in said threaded portion of said second end portion of said bottom bracket (30); a tube (20) fixedly mounted in said bottom bracket (30) and comprising a first end having a third outer threaded portion (202) formed along an outer periphery thereof and a second annular recess (21) defined in an inner periphery of said second end of said tube (20); an axle (10) rotatably mounted in said tube (20) and comprising a first end portion having a third annular recess (11) defined in an outer periphery thereof and a second end portion having a fourth annular recess (12) defined in an outer periphery thereof; a first ball bearing (42) rotatably mounted between said first annular recess (310) of said first bowl member (31) and said third annular recess (11) of said axle (10); and a second ball bearing (41) rotatably mounted between said second annular recess (21) of said tube (20) and said fourth annular recess (12) of said axle (10); characterised in that: said first bowl member (31) further has an inner threaded portion (314) formed along an inner periphery thereof and a first flange portion (316) formed on a distal end thereof, said third outer threaded portion (202) formed along an outer periphery of said tube (20) engaging in said inner threaded portion (314) of said first bowl member (31); said second bowl member (32) further has a first tapered surface (204) formed along an inner periphery thereof; said tube (20) further has a second end having a second tapered surface (324) formed along an outer periphery thereof for urging on said first tapered surface (204) of said second bowl member (32), and a second flange portion (22) formed on said first end of said tube (20) for abutting against said first flange portion (316) of said first bowl member (31). The bottom bracket assembly in accordance with claim 1, characterised by further comprising a first washer (44) mounted around said first end portion of said axle (10) and engaged in said first bowl member (31) for water-proofing, and a second washer (43) mounted around said second end portion of said axle (10) and engaged in said second end of said tube (20) for water-proofing.

Inventors: CHI YI-CHEN, CHI, YI-CHEN
Applicants: CHI YI CHEN, CHI, YI-CHEN
Application year: 1996
Main classification: B62K19
IPC codes: B62M3, F16C25, F16C19, F16C35