A BICYCLE FRAME COMPONENT, A METHOD FOR THE MANUFACTURE THEREOF, AND A BICYCLE FRAME
BACKGROUND OF THE INVENTION AND PRIOR ART
The present invention relates to a bicycle frame component comprising a single-piece body which is at least partly cylindrical and which comprises a plurality of wall surfaces which all extend generally perpendicularly to a commune cross-plane.
The invention also relates to a method of producing a bicycle frame component, which includes extruding a profile. The invention also relates to a bicycle frame comprising a plurality of extruded profiles or profile pieces.
A large variety of bicycle frames of this type and comprising one or more bicycle frame components of the type initially defined are already known. Also bicycle frame components produced by means of the method initially defined are already known. Here, the term extrusion also comprises extrusion pressing of profiles.
Nearly without exceptions, the bicycle frame components of the frame are connected with each other through welded joints. Thereby, very strong and reliable joints are obtained. A disadvantage of components to be joined in this way is, however, the amount of work and the costs that are inevitably implied by the welding. The problem is accentuated when metals that are difficult to weld, such as aluminium, form the main constituent in the components in question.
Often, it is also necessary to direct frames that are already welded, as the welding in itself induces tensions in the frame component material, and as these tensions result in skewness of the
frame in question. Directing welded frames requires work, time, and money.
Bicycle frames by which the components thereof are joined in other ways than through welding have also been proposed. Particularly, this is the case of those constructions, where the bicycle frame components are made of plastic materials. One example thereof is shown in the US patent US-A-5 464 240, in which moulded half-shelves of polymer are joined by means of screws, bolts, or rivets to form separate cylindrical tubes that form the frame. However, the bicycle frame components of that case differ, per definition, substantially from the type of components which the present invention relates to. This also goes for the method for producing them, and the frame formed by them.
There are also other types of weldless joints between bicycle frame components according to prior art. For example, as is suggested in the German patent document No. 1 12010, certain bicycle frame components may have connection sockets, while further bicycle frame components, here frame tubes, are screwed into these connection sockets, whereby the frame is mounted by means of screw-joints. However, this technology has its definite disadvantage. For example, the arrangement of the socket, and also the screwing procedure itself, require time as well as money. Even though this technique is very old, there have been tries lately to accomplish similar solutions, however, without any significant success; something that is proved by the fact that the dominating joining technique is still welding, in spite of its disadvantages as told of above.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a bicycle frame component which is easy to produce, which has a construction which is favourable for its torsional rigidity, and which can be brought to engagement in relation to a further frame component in a simple and reliable way, making it possible to lock the frame
component to said further frame component reliably by means of very simple means, such as screw or bolt joints.
This objective is achieved by means of a bicycle frame com- ponent of the type initially defined, which is characterised in that it comprises at least two separate wall surfaces which are generally flat and which extend generally in one plane each, and which are arranged to bear supportingly on a respective support surface of a further frame component. Thereby, the wall surfaces are arranged to either externally enclose or surround the support surfaces, or to be enclosed and surrounded by the support surfaces. The bicycle frame component as well as the further frame component are load-carrying parts of substantial importance for the ability of the frame to carry loads, as when a person is sitting on and riding the bicycle that they constitute a part of.
According to a further embodiment of the bicycle frame component, the at least two bearing wall surfaces are generally opposite and parallel to each other. Thereby, a very stable engagement may be obtained between the bicycle frame component and the further frame component. In the case where the bicycle frame component is elongated, it is preferably provided with said wall surface by at least one of its ends.
According to another preferred embodiment, the body comprises a wall which forms a rib that extends between opposite wall portions of the body in the lengthwise direction thereof. The body is elongated and the rib extends at least along a part of length of the body. Thanks to the rib, the body obtains an improved tor- sional rigidity. Anyone of the wall surfaces of the rib may also be used as a bearing wall surface for a support surface of a further frame component.
According to another preferred embodiment, the two opposite wall portions are connected to each other along a portion of the length of the body, such that a cavity is formed between them.
Thereby, the torsional rigidity of the component is improved.
Advantageously, the rib defined above extends through this cavity, and the opposite wall portions are formed by the walls of a cylinder having, for example, an elliptic shape, whereby a very high torsional rigidity of the component is obtained.
According to another preferred embodiment, the rib is exposed to be within reach from outside along a portion of the lengthwise direction of the body, that is not only through an end mouth of the component in question. Thereby, the rib can be used as a support surface, for instance for a further component, which is arranged to extend from the body in question to, for instance, a further bicycle frame component. For example, the rib can form a support for a bar which extends between the bicycle frame component and a further frame component connected thereto, when there is an angle between said components.
According to another preferred embodiment, the component is an extruded profile which comprises aluminium as its main constituent. The advantage of such a component is that it is easy to pro- duce, can be given good strength properties through a correct heat treatment, and by use of a correct alloy, and is corrosion resistant, and, above all, light.
According to a further embodiment, the component is any one of a bicycle's upper frame profile, extending from a steering bar guide to a saddle holder, a lower frame profile, extending from said steering bar guide to a pedal hub holder, said steering bar guide, said pedal hub holder, and an arm which extends from the region of the pedal hub to the region of the rear wheel hub for carrying the rear wheel of the bicycle.
Another object of the invention is to provide a method for producing a bicycle frame component, which method makes it possible to obtain a bicycle frame component by means of relatively simple means and a small amount of work, such that the bicycle frame component very easily can be brought into engagement with a further frame component in a stable and reliable way.
This is achieved by means of the method initially defined, which is characterised in that the component, by the extrusion, is provided with at least two separate wall surfaces which are gener- ally flat and extend generally in one plane each, and which are arranged to bear supportingly on a corresponding support surface respectively of a further frame component. The wall surfaces are arranged in order to either externally enclose and surround the support surfaces or to be enclosed and surrounded by the support surfaces.
According to a preferred embodiment, by way of the extrusion the component is given a body which is at least partly cylindrical, i.e. the cylindrical body extends at least along a part of the length of the component. Thereby, the component, which is supposed to be elongated, obtains a good torsional rigidity in spite of a possibly large length/cross-section ratio. When said bearing surfaces are arranged inside the cylindrical body, a supplementary further component provided with support surfaces can be displaced into it and engaged with it in a stable way, given that the fitting is tight.
According to another preferred embodiment, the component, by way of the extrusion, is given a cylindrical profile with a rib which extends between two opposite wall portions along the length of the component, such that the profile is divided into an upper and a lower half. The rib also contributes by further increasing the torsional rigidity of the profile. Furthermore, its wall surfaces may be used as bearing surfaces for an engagement with further components. Thereby, the walls of the rib are preferably flat.
According to another preferred embodiment of the method, one of the upper and lower half of the profile is bevelled along a part thereof, such that the rib is exposed to be within reach from out- side along this part. Thereby, the rib is made more easy to reach in order to act as a support surface for possible further components.
Another object of the invention is to provide a bicycle frame which is comprised by a plurality of frame components that, thanks to their construction, are very easy to manufacture and to bring into a fitting engagement with each other.
This object is achieved by means of a bicycle frame of the type initially defined, which is characterised in that profiles or profile pieces connected to each other are arranged to be brought into engagement with each other by means of displacement and with fitting, and that they are locked in this position by means of separate securing members. By a couple of profiles connected to each other, one portion of one of the profiles is thereby inserted into and surrounded by a portion of the second profile. Prefer- ably, the securing members are comprised by screws, bolts, rivets, pins or the like, whereby the need of welded joints by the frame is avoided. These securing members are arranged to prevent profiles or profile pieces connected to each other from being displaced from the engagement position into which they initially were displaced. The securing members preferably penetrate and extend crosswise to one or more mutual displacement directions of components connected to each other.
According to a preferred embodiment of the bicycle frame, each of the profiles or profile pieces comprises at least two separate wall surfaces which are generally flat and which extend generally in one plane each, and which are arranged to bear supportingly on a corresponding support surface respectively of a further profile or profile piece, which is in engagement and connected there- with. The further profile or profile piece may be of a construction corresponding to the extruded profile or profile piece in question, but could also be of a different construction. Thanks to the arrangement of the flat wall surfaces, which act as bearing surfaces, a very well defined and stable engagement position between separate profiles or profile pieces can be obtained. The portions mentioned above thereby comprise the wall surfaces and support surfaces respectively.
According to another preferred embodiment, the profiles or profile pieces comprise one or more of a bicycles upper frame profile, extending from a steering bar guide to a saddle holder, a lower frame profile, extending from said steering bar guide to a pedal hub holder, said steering bar guide, said pedal hub holder, and an arm which extends from the region of the pedal hub to the region of the rear wheel hub for carrying the rear wheel.
The invention also relates to a bicycle frame characterised in that it comprises at least one inventive bicycle frame component.
Further features and advantages of the invention will become clear through the following, detailed description, and the rest of the dependent patent claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Hereinafter, the invention will be described by way of example, but not to delimit it, with reference to the annexed drawings, in which:
fig. 1 shows a schematic exploded view of one embodiment of the inventive frame with its frame components,
fig. 2 shows a detail of the frame according to fig. 1 ,
fig. 3 shows another detail of the frame according to fig. 1 , and
figs. 4, 5, and 6 show cross-sections of profiles, out of which an upper frame profile, lower frame profile, and a rear arm of the frame, respectively, are produced.
DETAILED DESCRIPTION OF AN EMBODIMENT
In fig. 1 a schematic exploded view of an embodiment of the inventive frame is shown, the frame comprising a plurality of frame
components 1 -1 1 , which all are formed by extruded profiles, here extrusion pressed aluminium profiles, a plurality of which have been cut, bevelled, and provided with a plurality of holes for mutual joining of the components in question by means of screw, bolt, rivet joints, or the like.
The frame components comprise an upper frame profile 1 , a lower frame profile 2, a steering bar guide 3, a pedal hub holder 4, two arms 5 extending from the region of the pedal hub to the region of the rear wheel hub of a bicycle in order to hold the rear wheel, an intermediate piece 6, a bar 7, upper and lower bar holders 8, 9 respectively, support pieces 10, a front fork 1 1 , and a shock absorber 12. Furthermore, the frame comprises rear hub holders 13 that are to be inserted into the arms 5, and a saddle holder 14 to be inserted into and fixed in the upper frame profile 1 in order to carry a saddle.
The upper frame profile 1 is elongated, cylindric, and arranged to be connected with and extend from the lower frame profile 2 to the saddle holder 14. It is formed by an A-profile, shown in cross- section in fig. 4. The profile presents two opposite walls 15, 16 forming the legs of the A, and a rib 17. The internal wall surfaces 18, 19 of the walls 15, 16 are generally flat and extend in planes that are parallel to each other. The rib 17 comprises an upper and a lower wall surface 20, 12 respectively, which also are flat and run in planes that are parallel to each other. Moreover, the profile comprises opposite flanges 22, 23 projecting into the profile from the opposite walls 15, 16 thereof and running in the lengthwise direction of the profile. The upper frame profile 1 has been formed by bevelling the walls 15, 16 along the lengthwise direction of the profile, as can be seen in figs. 1 and 2. In an end region, where the upper frame profile 1 is to be displaced over and fixed to the lower frame profile 2, holes 24 are arranged in the walls 15, 16 in order to permit locking of the upper frame pro- file 1 in relation to the lower frame profile 2 in an engagement position, where the upper frame profile 1 , through a displacement, has been brought to bear with the wall surfaces 18, 19 of
the walls 15, 16 on corresponding support surfaces 25 respectively of the lower frame profile 2. The support surfaces of the latter have been formed as opposite flat surfaces have been cut out of opposite outer walls of said frame profile. The upper frame profile is pivotably arranged in relation to the lower frame profile 2.
The rib 17 extends along generally the whole length of the upper frame profile 1 with exception of the region where the latter sur- rounds and engages the lower frame profile 2. The flanges 22, 23 run along a substantial part of the length of the frame profile 1 and a bar holder 8 is arranged, such that it is displaceable with a part thereof between the rib 17 and the flanges 22, 23. The rib 17 and the flanges 22, 23 define opposite, parallel bearing surfaces, against which the bar holder 8 can be supported. The bar holder 8 is suitably fixed to the upper frame profile 1 by means of a screw or the like, said screw or the like being provided to penetrate a recess 26 provided in the upper profile 1 , said recess being provided in the rib 17 and running in the lengthwise direc- tion of the upper frame profile 1 . By displacing the bar holder 8 along the lengthwise direction of the upper frame profile 1 and by pivoting the upper profile 1 in relation to the lower frame profile 2, a displacement of the saddle position is enabled. It should also be stated that a further bar holder 9 is fixed to the lower frame profile 2, and that a bar 7 runs between and is connected to both of the bar holders 8, 9. The bar 7 as well as the bar holders 8, 9 are made of extruded profiles, here extrusion pressed aluminium profiles.
The lower frame profile 2 is elongated, cylindric, and extends from a steering bar guide to a pedal hub holder 4. The lower frame profile 2 is made of an extrusion pressed aluminium profile, having an elliptic cross-section and a rib 27 which extends inside the ellipse between opposite lateral walls 50, 51 thereof. The profile presents generally planar, inner wall surfaces 28, 29 which extend in generally opposite, parallel planes, and each wall surface 28, 29 extends on both sides of the rib 27 as seen in
the height direction of the ellipse. The wall surfaces 28, 29 form bearing surfaces, against which support surfaces of further components suitably may support. A generally flat wall surface 30, which is parallel to the wall surfaces 46, 47 of the rib 27 is also provided at one end of the profile, here the bottom of the ellipse. This surface and a lower wall surface of the rib 27 form opposite bearing surfaces which are generally parallel and which suitably can support a further component's corresponding support surfaces. As can be seen in fig. 1 , the pedal hub holder 4 is arrang- ed such that it can be inserted into one of the ends of the lower frame profile 2 in order to engage and be supported by the wall surfaces 28, 29 of the lower frame profile 2. Correspondingly, the steering bar guide 3 is arranged in such a way that a piece thereof, comprised by two parallel walls 31 , 32 with outer support surfaces, can be inserted into the opposite end of the lower frame profile 2 and bear with said support surfaces on and engage parts of the inner wall surfaces 28, 29 of the lower frame profile. A number of holes are indicated in the ends of the lower frame profile 2 as well as in the walls 31 , 32 of the steering bar guide 3 and in the walls 33, 34 of the pedal hub holder 4. These holes are to be penetrated by screws, bolts, pins, or the like in order to fix the components as they are inserted into each other in the way defined above.
The lower frame profile 2 is bevelled along a portion thereof, such that the rib 27 is exposed and a positioning of the bar holder 9 directly towards the latter is made possible. Thereby, the bar holder 9 is arranged in such a way that it can engage and be supported by the upper wall surface of the rib 27 as well as the wall surfaces 28, 29 of the lateral walls. It is also arranged in such a way that it can be fixed against the rib 27 by means of screw or bolt joints or the like.
The pedal hub holder 4 is made of an extrusion pressed alu- minium profile and comprises a cylindric part with an opening 35 for receiving a pedal hub (not shown). It also comprises another cylindric part, with an opening 36, said part being arranged such
that it can be inserted into and engage an intermediate piece 6. Thereby, the opening 36 is to be arranged in alignment with a corresponding opening 37 of the intermediate piece 6. By means of a shaft, not shown, or a bearing device, which penetrates the two openings 36, 37, the intermediate piece 6 and the pedal hub holder 4 are, accordingly, arranged in order to be pivotably connected to each other. There is also provided a shock absorber 12, which is to extend between and be connected to the intermediate piece 6 and the lower profile 2. In this case the shock absorber is to be directly connected to the intermediate piece, and to be connected to the lower frame profile 2 via the bar holder 9. Thanks to the pivotable arrangement of the intermediate piece 6 and the arrangement of the shock absorber, a rear axle suspension with a shock absorbing function is obtained by a bicycle with this frame.
Furthermore, the frame comprises two arms 5 which are to be connected with one of their ends, respectively, to the intermediate piece 6 and to receive at their second end, a rear hub holder 13 that is to carry the rear wheel of the bicycle. The arms 5 are made of an extrusion pressed aluminium profile, the cross- section of which is seen in fig. 6. The profile is a profile with a hole and a rib 38 which extends between the lateral walls 39, 40 thereof. Further, a number of flanges 41 -44 are arranged, such that they project from the lateral walls 39, 40 towards the interior of the profile 5. The flanges 41 -44 act as supports for the support pieces 10 that have the shape of sticks with a rectangular cross- section and that are to be inserted into one of the ends of the arms 5. The task of the support pieces 10 is to support a screw joint or the like between the arms 5 and the intermediate piece 6. They are provided with holes that are to be positioned in alignment with corresponding holes of the arms, and to be penetrated by screws, bolts, or the like. Further, the arms 5 comprise a flange 45 which extends from the rib 38. The flange 45 extends generally parallel to one 39 of the lateral walls of the arm 5, and generally perpendicularly to the rib 38 and the rest of the flanges 41 -44. Together with the rib 38 and the flat wall 39, it forms bear-
ing surfaces with which rear hub holders 13 are to be engaged. The flat wall 39 is arranged such that it can bear with its outside against the intermediate piece.
In order to accomplish the arms 5, profile pieces with the cross- section seen in fig. 6 have been bevelled at their lower side along a portion of the length of the profile piece in order to give the arms the design that can be seen in fig. 1 . As long as this can be permitted from a mechanical strength point of view, it is an advantage from a weight saving point of view.
As to the front fork 1 1 , it should be stated that also that one is made of an extrusion pressed aluminium profile, which has been bent in such a way that it presents the shape of a U . The bottom portion of said U is to be connected to the very steering bar or a part connected to the latter. Furthermore, the profile forming the fork is strengthened at the inside by means of another profile (not shown) which has been inserted into the former before it was bent. The part 52 connected to the steering bar penetrates the fork and is fixed by means of a fixing member (not shown), suitably a nut or the like, in order not to be displaced or turned in relation to the fork 1 1 . At both its ends, the fork is arranged to receive front hub holders 53, generally in the same way as in the case with the arms 5 and rear hub holders 13.
Figs. 2 and 3 show more in detail how the rod 7 is to be connected to the upper and lower frame profile 1 and 2, respectively, through the rod holders 8 and 9, respectively. It can also be seen how the shock absorber 12 is to be connected to the rod holder 9 through a screw joint, said rod holder 9 being connected to the lower frame profile 2.
It should be realised that the holes shown in figs. 1 -3 that are not specifically given any reference numbers are all provided to be penetrated by screws, bolts, rivets, or the like for a mutual joining of the bicycle frame components by means of screw, bolt, rivet, pin joints, or the like.
By producing a frame as defined above and with the bicycle frame components defined, it is thus possible to produce a bicycle, which, above all, is characterised in that it is strong and light, and has frame parts that can easily be substituted. The frame can be produced without the need of any welding procedures for the mutual joining of individual components. Thanks to the use of aluminium as a construction material and by avoiding any welding, the need of subsequent lacquering of the frame in order to conceal welded joints etc. is eliminated. One could do with anodising the frame, something that reduces the production costs further.
It is obvious that a plurality of variants and alternative embodi- ments of the method described above and the inventive frame, as well as the frame components thereof, will be obvious to the man skilled in the art without departing from the frame of the invention. Therefore, the invention should only be delimited by what is stated in the annexed claims, supported by the description and the annexed drawings.
For example, the rod holder 9 arranged by the lower frame profile 2 could be displaceably arranged in order to be fixed in different positions along the length of the lower frame profile.