CN1550406A - Crank arm for bicycle - Google Patents
Crank arm for bicycle Download PDFInfo
- Publication number
- CN1550406A CN1550406A CNA2004100379870A CN200410037987A CN1550406A CN 1550406 A CN1550406 A CN 1550406A CN A2004100379870 A CNA2004100379870 A CN A2004100379870A CN 200410037987 A CN200410037987 A CN 200410037987A CN 1550406 A CN1550406 A CN 1550406A
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- Prior art keywords
- arm
- bicycle
- shaft sleeve
- sleeve part
- claw
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Abstract
In the crank arm A for bicycle, an intermediate arm part 1, a base end boss part which is provided on one end part in the longitudinal direction of the intermediate arm part and fitted to a crank shaft of a bicycle, a tip boss part which is provided on the other end part in the longitudinal direction of the intermediate arm part with a pedal fitted thereto, and a gear mounting part having a plurality of fingers radially extending at equal intervals from the base end boss part with the axis thereof as a center and with front gears mounted thereon are integrally provided. In addition, in a pair of fingers adjacent to both sides of the intermediate arm part out of the plurality of fingers, the ends thereof are integrated the base ends of the intermediate arm part. A recessed part having a first part disposed in a longitudinal area integrated with the pair of fingers and a second part continuous from the first part to an intermediate part in the longitudinal direction of the intermediate arm part is formed in a back surface side of the intermediate arm part along the longitudinal axis of the intermediate arm part.
Description
Technical field
The present invention relates to bicycle crank arm, relate in particular to the right side crank arm of sprocket wheel before being equipped with.
Background technology
Crank web of bicycle is made of with the right side crank arm that is installed in the right part of above-mentioned bent axle the left crank arm of the left part that is installed in bent axle, and wherein crankshaft revolution is bearing on the axis (Bottom Bracket) of vehicle frame.The leading section of each crank arm is equipped with stretcher, but the crank arm on right side is equipped with preceding sprocket wheel.
Fig. 9 represents the traditional right side crank arm of an example.In this crank arm B, the middle arm 101 that be installed in cardinal extremity shaft sleeve part 102 on the bent axle, the front end shaft sleeve part 103 of stretcher is housed, between cardinal extremity shaft sleeve part 102 and front end shaft sleeve part 103, extends and be equipped with before sprocket wheel installation portion 104 these members of sprocket wheel integrally formed.Sprocket wheel installation portion 104 possesses 5 claws 141, and these claws are radial extension with equidistant from distance from cardinal extremity shaft sleeve part 102 on every side in its axle center, and the hole portion 142 of sprocket wheel before being used for installing is being set on each claw 141.
In recent years, its weight of the demand for development of bicycle was more and more lighter, and was like this too for each parts that constitute bicycle.In order to realize the purpose of above-mentioned crank arm B lightness, for example, arm 101 forms in the mode of hollow in the middle of can considering to make, and perhaps in its back side one side recess is set.But, in this crank arm B, especially trample stretcher and when bicycle is driven, powerful flexure stress effect thereon, this flexure stress is big more near cardinal extremity shaft sleeve part 102 more.Therefore, do not add any consideration and adopt the method for above-mentioned lightness, the local strength of crank arm B is reduced, therefore must avoid making in this way.
Summary of the invention
This invention is based on above-mentioned situation and draws, and its problem is to provide a kind of lightness crank web of bicycle of not damage strength.
For solving above-mentioned problem, in this invention, adopted following technological means.
Promptly, the crank web of bicycle that this invention provided, it is characterized in that, this crank web of bicycle be in the middle of arm, cardinal extremity shaft sleeve part, front end shaft sleeve part, these member one of sprocket wheel installation portion and the crank web of bicycle that forms, wherein, the cardinal extremity shaft sleeve part is arranged on end of length direction of this centre arm, and is installed on the bent axle of bicycle; The front end shaft sleeve part is arranged on another end of the length direction of above-mentioned middle arm, and stretcher is installed; The sprocket wheel installation portion has a plurality of claws, and they are the center from above-mentioned cardinal extremity shaft sleeve part with its axle center, are radial with equidistant from distance and stretch out, and preceding sprocket wheel is housed simultaneously; Wherein, in above-mentioned a plurality of claw, the both sides of arm in the middle of above-mentioned and a pair of claw of adjacency, the cardinal extremity of its cardinal extremity and above-mentioned middle arm becomes one, the back side one side of arm in the middle of above-mentioned is formed with recess along the length-wise axis of this centre arm, and this recess has first and second portion, first is configured in the length direction zone that forms one with above-mentioned a pair of claw, and second portion extends to the length direction pars intermedia of above-mentioned middle arm from this first.
In preferred embodiment, above-mentioned recess forms as follows, and its first has deep, and reduces gradually in the second portion degree of depth.
In a plurality of claws, adjacent a pair of claw becomes one at its cardinal extremity and middle arm owing to clip middle arm, therefore, when trampling stretcher energetically, the section factor that can resist near the powerful bending moment of the base end part (the cardinal extremity shaft sleeve part) of arm in the middle of concentrating on obviously increases.Therefore, in this invention, only limit forms recess at the cardinal extremity of this centre arm in its back side one side.By adopting this structure, though form the weight that recess can alleviate crank arm, its intensity can not produce any problem yet.And, because recess is formed at the back side one side of middle arm, therefore, also can not influence the outward appearance of surface one side of crank arm.
In addition in a preferred embodiment, in above-mentioned each claw, at least in the middle of above-mentioned on the back side one side of a pair of claw of the both sides adjacency of arm, form the rib that extends along its length-wise axis respectively, and, the first of above-mentioned recess is connected with the side of above-mentioned rib and the side of above-mentioned cardinal extremity shaft sleeve part.
By adopting this structure, in the first of above-mentioned recess, can enlarge its shared zone to greatest extent, like this, just can further alleviate the weight of crank arm.In addition, be connected with the side of rib by the first that makes recess, further expansion should be resisted the concentrated section factor of flexure stress of the base end part that is applied to above-mentioned middle arm, thereby can carry out intensity compensation.And, can guarantee the intensity of each claw, and make its weight saving, so just can further alleviate the weight of crank arm.
In addition in a preferred embodiment, in the length direction pars intermedia of the back side one side of above-mentioned each claw, it is linked to each other with above-mentioned rib, so the shaft sleeve part that the installation sprocket wheel is used is with regard to the one expansion molding.
So shaft sleeve part increases above-mentioned section factor all the more, therefore can further guarantee intensity compensation to the flexure stress on the arm in the middle of acting on.
Further feature of this invention and advantage, carrying out following detailed explanation by the reference accompanying drawing then can be clearer.
Description of drawings
Fig. 1 is the exploded perspective view of a routine bicycle drive division.
Fig. 2 is the front elevation of a routine crank web of bicycle of this invention.
Fig. 3 is the left surface figure of crank web of bicycle shown in Figure 2.
Fig. 4 is the back view of crank web of bicycle shown in Figure 2.
Fig. 5 is the section-drawing along the V-V line of Fig. 2.
Fig. 6 is the section-drawing along the VI-VI line of Fig. 4.
Fig. 7 is the section-drawing along the VII-VII line of Fig. 4.
Fig. 8 is the section-drawing along the VIII-VIII line of Fig. 4.
Fig. 9 is the back view of a routine traditional crank arm.
The specific embodiment
Below with reference to Fig. 1～Fig. 8, the preferred implementation of this invention is specifically described.
As shown in Figure 1, crank web of bicycle A is installed on the bent axle 5 (with reference to Fig. 5) on bicycle right side, thus sprocket wheel 6a～6c before can supporting.As shown in Figure 2, this crank web of bicycle A have bar-shaped middle arm 1, respectively be formed at length direction one end (base end part) of this centre arm 1 and the cardinal extremity shaft sleeve part 2 on the other end (leading section) and front end shaft sleeve part 3, install before the sprocket wheel installation portion 4 used of sprocket wheel 6a～6c, these members are material and integrally formed with aluminum alloy etc.
As shown in Figure 5, form direction of principal axis through hole 20 in cardinal extremity shaft sleeve part 2.This direction of principal axis through hole 20 has taper square hole portion 21 and spot-facing portion 22, wherein taper square hole portion 21 dwindles more to the D1 of this direction of principal axis foreign side more, and spot-facing portion 22 is formed at the outer aspect of above-mentioned cardinal extremity shaft sleeve part 2, and it has the big internal diameter of catercorner length than the outer square end of above-mentioned taper square hole portion 21.In the present embodiment, taper square hole portion 21 has the shape of the section that slightly is square, and a bevel angle relative with the axle of the cardinal extremity shaft sleeve part 2 of its inner face is between 1.8 °～2.2 °.This taper square hole portion 21 is that taper is entrenched in the part on the taper angle axial region 51, and taper angle axial region 51 is formed at the end of bent axle 5, and therefore, the taper angle axial region 51 that is formed at the end of bent axle 5 also has the bevel angle that equates with above-mentioned taper square hole portion 21.
Form tapped bore 31 on front end shaft sleeve part 3, it has the axis parallel with the taper square hole portion 21 of above-mentioned cardinal extremity shaft sleeve part 2, and stretcher axle (diagram is omitted) is screwed in this tapped bore.
As Fig. 2 and shown in Figure 4, sprocket wheel installation portion 4 possesses 5 claw 41a～41e, and they are radial with equal intervals around the heart therein from cardinal extremity shaft sleeve part 2 and stretch out.Leading section at each claw 41a～41e forms hole portion 42, as shown in Figure 1, preceding sprocket wheel 6a, 6b is installed exactly by using these hole portions 42.As shown in Figure 5, and in the back side one side of the length direction pars intermedia of each claw 41a～41e, towards interior side D2 and the outstanding shaft sleeve part 43A that forms, this shaft sleeve part 43A is formed with tapped bore portion 43.As shown in Figure 1, preceding sprocket wheel 6c is installed exactly by using these tapped bore portions 43.In addition, in the back side of each claw 41a～41e one side, as Fig. 4 and shown in Figure 7, form rib 44 in its Width central authorities, it extends from the side of above-mentioned cardinal extremity shaft sleeve part 2 along the length-wise axis of claw.This rib 44 also is connected with above-mentioned shaft sleeve part 43A.
In above-mentioned claw 41a～41e, with a pair of claw 41a, the 41b of above-mentioned middle arm 1 adjacency, the cardinal extremity of its cardinal extremity and middle arm 1 becomes one.In this centre arm 1, comprise the length direction zone that becomes one, probably be only limited to cardinal extremity, form axis along its length and the recess 7 that extends in its back side one side.
Its particular case is, as shown in Figure 4, above-mentioned recess 7 has first 71 and second portion 72, wherein, in the length direction zone that arm 1 and a pair of claw 41a, 41b became one in the middle of first 71 was configured in, and second portion 72 is configured in the front E2 of middle arm 1.When forming first 71, make side and the rib 44 of a pair of claw 41a, 41b and the side smooth connection of projection 43A of itself and cardinal extremity shaft sleeve part 2.As shown in Figure 8, and the second portion 72 of recess 7 forms in the mode that is formed wall 73 by recess and surround, and as shown in Figure 4 at its peristome, just becomes more little towards front E2 Width W size more.
As shown in Figure 4, recess forms wall 73 and has level and smooth outstanding protrusion 73a, so the Width size on the border of the first of recess 7 and second portion 71,72 is extremely narrow, and more towards second portion, the Width size enlarges all the more.In addition, as shown in Figure 5, the deep of recess 7 is positioned at first 71, and more towards second portion 72, its degree of depth reduces all the more.
In addition, as shown in Figure 8, above-mentioned recess forms wall 73 and has rib shape portion 74, and it is as the rib shape by carry out face 73a that above-mentioned chamfered produces in middle arm 1.
Effect to the bicycle crank arm A of above-mentioned structure describes below.
By forming above-mentioned recess 7 and it is carried out above-mentioned chamfered, then can make the weight saving of above-mentioned crank web of bicycle A at middle arm 1.
On the bicycle that this crank web of bicycle A is housed, when trampling stretcher, the Width W of middle arm 1 bears powerful stress, and this stress is very big at the cardinal extremity of middle arm 1.But, in the crank arm A of above-mentioned structure and since the cardinal extremity of middle arm 1 with become one at the claw 41a of its both sides adjacency, the cardinal extremity of 41b, therefore, the section factor that can resist above-mentioned flexure stress increases.Because recess 7 is connected with rib 44 that is arranged on claw 41a, 41b or shaft sleeve part 43A, therefore above-mentioned section factor increases all the more in addition.So even if above-mentioned so powerful flexure stress is applied to it, its intensity does not have any problem yet.And, owing to the recess 7 in this embodiment is connected with the side of above-mentioned rib 44 or cardinal extremity shaft sleeve part 2, so, the shared zone of recess is enlarged, the effect that alleviates crank arm weight by this recess is apparent in view.So the crank web of bicycle A of above-mentioned structure can realize intensity compensation and lightness well.
In addition, arm 1 and a pair of claw 41a, 41b boundary member in the middle of stress when trampling stretcher also concentrates on, but, form wall 73 with the recess of the cooresponding middle arm 1 of this stress concentration part, strengthened by rib shape portion 74, make the gauge of Width W become big by above-mentioned protrusion 73a simultaneously, therefore, can resist above-mentioned concentrated stress.In addition, from the distolateral forward E2 of the base end side E1 of middle arm 1, recess 7 shoals, and like this, the thickness of recess 7 diapires is becoming thicker with the cooresponding place of above-mentioned stress concentration part, does not have local variation simultaneously.Therefore, the diapire of this recess 7 also has the effect of the above-mentioned concentrated stress of opposing.So as mentioned above, in this crank web of bicycle, only the cardinal extremity at middle arm forms recess, therefore, do not form that section factor can not be reduced to more than necessity yet in the zone of this recess.
As above explanation, above-mentioned crank web of bicycle A is damage strength and realize lightness not.
Certainly, scope of the present invention is not limited to above-mentioned embodiment.For example, above-mentioned sprocket wheel installation portion 4 also can be the structure that 3 preceding sprocket wheel 6a～6c can be installed, and also can be by omitting above-mentioned jut 43A, the structure of 2 or 1 preceding sprocket wheels being installed.
Claims (4)
1. crank web of bicycle, it is characterized in that, be in the middle of arm, cardinal extremity shaft sleeve part, front end shaft sleeve part, these member one of sprocket wheel installation portion and form, wherein, the cardinal extremity shaft sleeve part is arranged on end of length direction of this centre arm, and is installed on the bent axle of bicycle; The front end shaft sleeve part is arranged on another end of the length direction of described middle arm, and stretcher is installed; The sprocket wheel installation portion has a plurality of claws, is the center from described cardinal extremity shaft sleeve part with its axle center, is radial with equidistant from distance and stretches out, and preceding sprocket wheel is housed simultaneously,
In described a plurality of claws, a pair of claw of the both sides adjacency of arm in the middle of described, its base end side becomes one with the base end side of described centre arm.
Rear side at described middle arm, length-wise axis along this centre arm forms recess, this recess has first and second portion, first is configured in the length direction zone that becomes one with described a pair of claw, and second portion extends to the length direction pars intermedia of described middle arm from this first.
2. crank web of bicycle as claimed in claim 1 is characterized in that,
Described recess forms, and its first has deep, and reduces gradually in the second portion degree of depth.
3. crank web of bicycle as claimed in claim 2 is characterized in that,
In described each claw, at least in the middle of described on the back side one side of a pair of claw of the both sides adjacency of arm, form the rib that extends along its length-wise axis respectively, and, the first of described recess is connected with the side of described rib and the side of described cardinal extremity shaft sleeve part.
4. crank web of bicycle as claimed in claim 3 is characterized in that,
In the length direction pars intermedia of the back side of described each claw one side, link to each other with described rib, and the one expansion is formed with the shaft sleeve part that the installation sprocket wheel is used.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2003137136 | 2003-05-15 | ||
| JP2003137136A JP2004338538A (en) | 2003-05-15 | 2003-05-15 | Crank arm for bicycle |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1550406A true CN1550406A (en) | 2004-12-01 |
Family
ID=33526875
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNA2004100379870A Pending CN1550406A (en) | 2003-05-15 | 2004-05-14 | Crank arm for bicycle |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP2004338538A (en) |
| CN (1) | CN1550406A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102099244A (en) * | 2008-07-21 | 2011-06-15 | 3T设计有限公司 | Crank set for a bicycle |
| CN109421879A (en) * | 2017-08-21 | 2019-03-05 | 株式会社岛野 | Crank arm |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010058589A (en) | 2008-09-02 | 2010-03-18 | Sugino Engineering:Kk | Bicycle gear crank |
| CN103538681B (en) * | 2012-07-10 | 2015-07-22 | 耀马车业(中国)有限公司 | Improved structure of chainwheel and crank for electric bicycle |
-
2003
- 2003-05-15 JP JP2003137136A patent/JP2004338538A/en active Pending
-
2004
- 2004-05-14 CN CNA2004100379870A patent/CN1550406A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102099244A (en) * | 2008-07-21 | 2011-06-15 | 3T设计有限公司 | Crank set for a bicycle |
| CN109421879A (en) * | 2017-08-21 | 2019-03-05 | 株式会社岛野 | Crank arm |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2004338538A (en) | 2004-12-02 |
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| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C02 | Deemed withdrawal of patent application after publication (patent law 2001) | ||
| WD01 | Invention patent application deemed withdrawn after publication |