GB2385641A - Internal assembly semi-cartridge bearing arrangement - Google Patents

Abstract

An internal assembly semi-cartridge bearing arrangement for the bottom bracket of a bicycle is disclosed wherein an axle shaft A is positioned relative to frame F and cartridge radial bearings B-1 and B-2, B-3 and B-4, are press-fitted in to fixed bottom bracket cup C-1 and cup C-2 respectively, and spacers OS-1 and OS-2 are press-fitted in to extended lips C-1 and C-2 respectively (between cartridge radial bearings B-2 and B-3). An internal spacer IS is centrally located over axle A, which are then both inserted in to radial bearings B-2, B-1 from the bottom bracket cup C-2 region. The alignment of spacers IS and OS-2 within the bicycle frame produces a full cartridge unit having fully tightened cups so as to prevent the ingression of dirt or water. The overall aim of the invention is to provide smooth rotation of a bicycle's pedal crank arms.

Description

<Desc/Clms Page number 1>

Internal Assembly Semi Cartridge Bottom Bracket.

This invention relates to the'bottom bracket'bearing assembly used on a bicycle to allow the smooth rotation of the pedal crank arms.

Bicycle pedal cranks have been evolving in to different areas. For certain uses a high strength crank arm assembly is required. To that end, many manufacturers are currently offering'oversize'axles together with oversize arms.

This development was primarily designed for the larger American Standard'BMX' type frame shells. Obtaining robust, high strength bearings to operate between the press fit, fixed position, frame cups and the large diameter axle has not been a problem.

However, the strength of the BMX type oversize axle and crank has become desirable to use on other designs of Bicycle that use the'English Standard Threaded'bottom bracket shells. This factor significantly reduces the available bearing space between the frame (F) and axle (A), causing manufacturers to utilise small, relatively fragile industrial cartridge radial bearings (Bl, 2, 3 & 4).

Longevity of these small bearings operatmg under high loads has become a potential problem.

I have identified one primary factor which would be extremely beneficial in significantly extending bearing longevity ; The existing'Oversize Axle'type cranksets for use within'English Bottom Brackets' utilise threaded frame cups and a central axle bearing spacer. This assembly system allows the fitter to apply an optional and variable sideload to the bearings during assembly and subsequent use.

I believe that the radial type Industrial cartridge bearings commonly utilised within these assemblies are being destroyed ahead of their potential life in most cases by a relatively un-quantifiable factor relating to the sideload applied. Additionally, there is a potential problem with the ingress of water and Dirt into the bearings from inside of the frame.

Accordingly, I have designed a secondary'external edge cartridge bearing'spacer system (OS-1 and OS-2) which equals the effective spacing size of the inner edge axle spacer (IS). This equalised spacing system eliminates the'unknown'side loading factor during assembly and therefore allows the radial cartridge bearing to rotate along their designed axis without significant side-loading, and thus to maximise the bearing life.

To attain a functional completed assembly with maximum bearing space I have designed a Semi-Cartridge unit (see Note 2 below).

<Desc/Clms Page number 2>

The key component (s) that allows this functionality are the'split, self aligning Outer Spacers (OS-1 and OS-2).

This'Split part'allows an effective'Cartridge Type Unit'to be assembled easily within the bicycle frame itself (i. e.'Blind').

Additionally, my design benefits also offers partial water sealing to the internal of the bottom bracket by the assembled appearance of a'cartridge type'complete unit once in position.

Note 1: The design attached uses a separate inner bearing spacer (IS), but this part can also be an integral part of the Axle (A). The only difference being that the separate spacer (IS) and Axle (A) allow for the Axle (A) to adjust to differing'chainlines'by using external spacers and crank arm fixings.

An integral Axle & Inner spacer would be more suited to non-sliding axle assemblies where specific pre-determined chainline would be utilised.

The system would in all other aspects function in the same manner.

Note 2: Pre-assembled'cartridge'type bottom bracket units have been used extensively in the bicycle industry with conventional sie axles for many years with great success. Such pre-assembled cartridge units require additional space to be utilised in securing the unit into the frame... i. e. The internal radial bearings are fitted inside the'cartridge wall', the'cartridge wall'is then inserted into threaded cups that allow assembly into the frame. Thus, the conventional'cartridge unit'requires an additional'cartridge wall'before fitment into the frame cups.

However, due to the minimum space available when using'Oversize'axles, it is desirable to remove the need for the'cartridge wall'and fix the radial bearings directly into the threaded cups, therefore maximising the use of the potential space and allowing the biggest bearing size possible.

Note 3: The'Semi-cartridge system'allows separate components to be altered or repaired without replacing the complete'Cartridge Unit'. e. g. If an axle were to become bent or damaged by accident, then ONLY that part need be replaced, instead of replacing the complete Cartridge Unit, as would be the accepted normal procedure for the Complete Cartridge Type units noted above in 2.

<Desc/Clms Page number 3>

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which ; Assembly system, from initial external components ;

1) Radial Bearings Bl an B2 are'light press-fit'into'Fixed'Bottom Bracket Cup C-l OS-1 is a light press-fit into the extended lip on Bottom Bracket Cup C-l behind B2.

2) Radial Bearings B3 and B4 are'light press-fit'into Bottom Bracket Cup C-2 OS-2 is a light press-fit into the extended lip on Bottom Bracket Cup C-2 behind B3.

3)

C-l (including Bl, B2 and OS-1) is threaded directly into Bicycle frame (F) until the outside'lip'of C-l secures to the edge ofF.

4) Internal Spacer IS is positioned centrally over Axle A (see also Notel above re : integral axle/spacer). A and IS are then inserted into B2JB1 and Cl from the C2 end of the opening in F.

5) C-2 (including B3, B4 and OS2) is screwed directly into F from C-2 side.

C2 end of Axle (A) passes into B3, B4 and C2.

OS-2 Cone'picks-up'08-1 and automatically aligns OS-2 and OS-I together.

C-2 is fully tightened into F.

6) Semi Cartridge System is now an effective Full Cartridge Unit with fully tightened cups and adjusted cups bearings and effective internal Water and Dirt sealing.

No further adjustments are required.

Claims (7)

CLAIMS;

1) A bicycle bottom bracket system that allows the internal assembly (i. e.'Blind' within the frame) of a'cartridge type'unit.

2) Radius'cone nose'spacer (part OS-2) allows simple assembly and perfect alignment within the bicycle frame, as per 1 above.

3) Internal assembly of the'semi-cartridge unit'as per 1 & 2 noted above allows maximum of the potential space available between axle and frame by removing the need for a conventional cartridge unit wall between the external edge of the radial bearings and the internal of the frame cups.

4) Inner and outer equalised radial cartridge bearing spacers remove excess side loading to the radial bearings.

5) Once assembled, the'Semi-Cartridge'forms an effective'cartridge'and thus protects the complete assembly from the ingress of water and dirt from inside the bicycle frame.

6) The'Semi-cartridge system'allows separate components to be altered or repaired without replacing the complete'Cartridge Unit'

7) An Internal Assembly Semi-Cartridge Bicycle Bottom Bracket unit as described herein with reference to an example shown in figures 1,2 & 3 attached.