JP3005801U - Bicycle crank arm connection structure - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a bicycle crank arm connection structure capable of firmly connecting and fixing a crank shaft and a crank arm that constitute a bicycle. [Structure] Since a tightening member formed by an elastic body is appropriately interposed between the tightening members screwed to one end of the crankshaft and the insertion holes formed in the base end of the crank arm, the tightening member is tightened. The loosening member is elastically deformed by the tightening force of the tightening member such as the tightening nut or the tightening bolt, and the loosening member is closely adhered to the mating pressure contact surface without a gap, thereby correcting mutual dimensional errors. In addition, the shock and vibration applied at the time of getting on and off the vehicle are buffered by the elasticity of the loosening member, and the looseness and looseness of the mutual connecting portions are prevented. In addition, the elasticity of the loosening prevention member and the loosening prevention projection prevents the tightening member from rotating in the loosening direction, and maintains the state in which they are firmly connected and fixed to each other for a long period of time.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a bicycle crank arm connecting structure used for connecting and fixing a crank shaft and a crank arm that constitute a bicycle, for example.

[0002]

[Prior art]

 Conventionally, as a method of connecting and fixing the crank shaft and the crank arm as in the above-described example, for example, a crank shaft is supported on a hanger portion of a frame body that constitutes a bicycle, and the crank shaft is projected to both end side center portions of the hanger portion. The insertion parts formed at both ends of the crankshaft and the insertion holes formed at the base ends of the crank arms are fitted to each other, and the insertion parts of the crankshaft projecting to the center of each insertion hole. There is a connection method in which a tightening nut or a tightening bolt is screwed and fixed via a metal washer.

[0003]

[Problems to be solved by the device]

 However, if the machining accuracy of either the crank arm or crank shaft described above is poor and the dimensional error that occurs at the mating parts is large, the insertion parts formed on the crank shaft and the insertion parts formed on the crank arm. Since there is a gap in the fitting part with the hole, it is difficult to match and fix each other. Moreover, since the tightening nut or the tightening bolt is screwed and fixed to one end of the crank shaft via the metal washer, if an excessive tightening force is applied to the tightening nut or the tightening bolt, the metal The pressure contact part of the parts is significantly worn out, and the tightening force necessary for connecting and fixing the crankshaft and the crank arm cannot be obtained.

In addition, since one foot is placed on the pedal of the crank arm connected to the entry / exit side (generally left side) of the bicycle, there is looseness in the connecting portion between the crank shaft and the crank arm, and therefore there is play during entry / exit. There is a problem that the tightening nut or the tightening bolt may be loosened due to the momentary impact applied, and the crank arm may fall off from one end of the crank shaft when riding or running. .

In view of the above problems, the present invention forms an appropriate elastic body between the facing surfaces of the tightening member screwed to one end of the crankshaft and the insertion hole formed at the base end of the crank arm. An object of the present invention is to provide a crank arm connecting structure for a rotating vehicle, in which a crank shaft and a crank arm are fitted and fixed to each other by interposing a loosening member, and can be maintained in a strongly connected and fixed state for a long period of time.

[0006]

[Means for Solving the Problems]

 The invention according to claim 1 is characterized in that the pressure contact side peripheral edge portion of the tightening member screwed into one side end portion of the crankshaft and the press contact side peripheral edge portion of the insertion hole formed at the base end portion of the crank arm are opposed to each other. It is characterized in that the bicycle crank arm has a structure in which a loosening member having elasticity is interposed between the surfaces.

According to a second aspect of the invention, in addition to the structure of the first aspect of the invention, a loosening member is provided on the pressure contact side of the tightening member facing the pressure contact side peripheral portion of the insertion hole formed in the crank arm. It is characterized in that it is a connecting structure of a bicycle crank arm covered with.

According to a third aspect of the present invention, in addition to the configuration of the first aspect of the invention, a locking member is provided on the pressure contact side of the tightening member facing the pressure contact side peripheral edge portion of the insertion hole formed in the crank arm. It is characterized in that it is a structure for connecting bicycle crank arms to which is fixed.

According to a fourth aspect of the present invention, in addition to the configuration of the first aspect of the invention, elastic force is applied to the pressure-contact side peripheral edge portion of the loosening member in a direction opposite to the loosening direction of the loosening member. It is characterized in that it is a structure for connecting bicycle crank arms, which is formed with a loosening protrusion for giving

According to a fifth aspect of the present invention, in addition to the structure of the first aspect of the invention, a proper number of loosening protrusions are formed in the circumferential direction on the pressure-contact side peripheral portion of the loosening member. It is characterized in that it has a structure for connecting bicycle crank arms.

According to a sixth aspect of the present invention, in addition to the configuration of the first aspect of the invention, either one of the press contact side peripheral edge portion of the insertion hole formed in the crank arm or the press contact side peripheral edge portion of the tightening member is provided. An annular recess is formed on the one side, and a ring-shaped loosening member is fitted and fixed in the annular recess formed on the one pressure-contact side peripheral edge portion, and the pressure-contact side peripheral edge portion of the locking member is located outside the annular recessed portion. It is characterized in that it is a bicycle crank arm connection structure that is appropriately protruded.

According to a seventh aspect of the invention, in addition to the configuration of the sixth aspect of the invention, the slack stop member is loosened at the peripheral edge portion of the slack stop member projecting outward from the annular recess. It is characterized in that it is a structure for connecting bicycle crank arms, which is formed with a locking protrusion that imparts elasticity in a direction opposite to the direction.

The invention according to claim 8 is, in addition to the structure of the invention according to claim 1, a crank for a bicycle, comprising a tightening nut that is screwed onto a screw shaft formed in the insertion portion of the crankshaft. It is characterized in that it has an arm connection structure.

According to a ninth aspect of the present invention, in addition to the configuration of the first aspect of the invention, a bicycle crank including a tightening bolt that is screwed into a screw hole formed in the insertion portion of the crankshaft. It is characterized in that it has an arm connection structure.

[0015]

[Action]

 In the connecting structure according to claim 1, an elastic loosening member is interposed between the facing surfaces of the tightening member screwed into one end of the crankshaft and the insertion hole formed in the base end of the crank arm. This tightening prevents the tightening member from rotating in the loosening direction due to the contact resistance of the locking member. In addition, the loose-fitting member closely adheres to the press-contact surface of the other side without any gap, compensating for mutual dimensional error and cushioning the impact and vibration applied when getting on and off.

According to a second aspect of the present invention, in addition to the operation of the first aspect, a loosening stop member is provided on the pressure contact side of the tightening member facing the pressure contact side peripheral edge of the insertion hole formed in the crank arm. The coating facilitates the handling and management of the assembled parts.

According to a third aspect of the present invention, in addition to the action of the first aspect, a loosening stop member is provided on the pressure contact side of the tightening member facing the pressure contact side peripheral edge portion of the insertion hole formed in the crank arm. By fixing, it becomes easy to handle and manage the assembled parts.

In the connection structure according to the fourth aspect, in addition to the action according to the first aspect, the tightening member is rotated in the loosening direction by the elasticity of the loosening protrusion formed on the peripheral edge portion of the loosening member on the pressure contact side. Prevent.

In the joint structure according to the fifth aspect, in addition to the action according to the first aspect, the contact area and the contact resistance are large due to the elastic deformation of the loosening protrusion formed on the peripheral edge portion of the loosening member on the pressure contact side. Therefore, the tightening member is prevented from rotating in the loosening direction.

According to a sixth aspect of the present invention, in addition to the operation of the first aspect, the connecting structure is provided on either the pressure contact side peripheral edge portion of the insertion hole formed in the crank arm or the pressure contact side peripheral edge portion of the tightening member. By fitting and fixing the ring-shaped loosening member in the formed annular recess, it is possible to prevent the tightening member from rotating in the loosening direction, as in the case of claim 1.

In the connection structure according to claim 7, in addition to the operation according to claim 6, the tightening member rotates in the loosening direction by the elasticity of the loosening protrusion formed on the protruding side peripheral surface portion of the loosening member. Prevent.

According to the connection structure of claim 8, in addition to the effect of claim 1, by screwing a tightening nut to a screw shaft formed in the insertion portion of the crankshaft via a locking member, Similar to the first aspect, the tightening nut is prevented from rotating in the loosening direction.

According to a ninth aspect of the present invention, in addition to the operation of the first aspect, the tightening bolt is screwed into the screw hole formed in the insertion portion of the crankshaft via the locking member, As in the first aspect, the tightening bolt is prevented from rotating in the loosening direction.

[0024]

[Effect of device]

 According to this invention, a loosening member formed of an appropriate elastic body is interposed between the facing surfaces of the tightening member screwed into one end of the crankshaft and the insertion hole formed in the base end of the crank arm. Since the tightening force of the tightening members such as tightening nuts and tightening bolts causes the loosening member to elastically deform, and the loosening member comes into close contact with the mating pressure contact surface without any gap, mutual dimensional error will occur. It can be corrected, and the crankshaft and the crank arm can be fitted and fixed to each other. In addition, the momentary shock and vibration applied at the time of getting on and off the vehicle is buffered by the elasticity of the loosening prevention member, and it is possible to reliably prevent looseness or looseness from occurring at the mutual connecting portions.

Furthermore, the elasticity of the loosening protrusion formed on the loosening member prevents the tightening member from rotating in the loosening direction, and the elastic deformation of the loosening member and the loosening protrusion causes the contact area to the other side and Since the contact resistance is increased, it is possible to positively prevent the tightening members from rotating in the loosening direction, and it is possible to maintain a state in which they are firmly connected and fixed to each other for a long period of time. At the same time, by integrally mounting the tightening member or the loosening member on the peripheral edge of the crank arm on the pressure contact side, the parts can be handled and managed easily without being lost during assembly.

[0026]

【Example】

 1 and 2 show a crank arm for a bicycle according to a first embodiment in which both axial ends of a crank shaft 3 constituting a bicycle 1 and left and right crank arms 5, 5 are connected and fixed by respective tightening nuts 6, 6. The connecting structure of the bicycle crank arm is such that the crank shaft 4 is rotatably supported by the hanger portion 3 of the frame body 2 of the bicycle 1, and the crank arm is provided at the center of both ends of the hanger portion 3. Both shaft ends of the shaft 4 are appropriately projected. After that, the square insertion portions 4a, 4a formed at both shaft end portions of the crankshaft 4 and the square insertion holes 5a, 5a formed at the base end portions of the crank arms 5, 5 are fitted respectively. The connecting structure is such that the tightening nuts 6 and 6 are respectively screwed into and fixed to the respective inserting portions 4a and 4a of the crankshaft 4 projecting from the central portions of the respective inserting holes 5a and 5a.

As shown in FIG. 3, FIG. 4, and FIG. 5, the above-mentioned tightening nut 6 is provided, for example, on the entire pressure contact side of the tightening nut 6 facing the pressure contact side peripheral portion of the insertion hole 5 a formed in the crank arm 5. The locking member 7 formed of an appropriate elastic material such as synthetic rubber or synthetic resin is integrally formed, and the wedge-shaped locking projections 7a are formed in a circular shape on the peripheral edge of the locking member 7 on the pressure contact side. Appropriate locations (for example, 4 locations and 6 locations) are formed at predetermined intervals in the circumferential direction, and the respective locking protrusions 7a are provided with elasticity in a direction opposite to the loosening direction of the tightening nut 6. It has a wedge shape.

That is, when the crank shaft 4 and the crank arm 5 are connected and fixed by the tightening nut 6, the crank shaft 4 and the crank arm 5 are formed at the base end portion of the crank arm 4 and the insertion portion 4 a formed at one end portion of the crank shaft 4. The tightening nut 6 is engaged with the screw shaft 4b formed in the inserting portion 4a of the crankshaft 4 by tightening the tightening nut 6 so that the loosening member 7 is secured by the tightening force of the tightening nut 6. Since the elastic member is elastically deformed and the loosening member 7 is closely attached to the peripheral edge portion of the insertion hole 5a formed in the crank arm 5 on the pressure contact side without any gap, mutual dimensional error can be corrected and the crankshaft 4 and the crank arm 5 can be corrected. Can be fitted and fixed to each other. In addition, the momentary impact and vibration applied when getting on and off the vehicle is buffered by the elasticity of the locking member 7, and it is possible to reliably prevent rattling or loosening at the connecting portion between the crankshaft 4 and the crank arm 5. .

Moreover, the elasticity of the respective loosening protrusions 7a formed on the loosening member 7 prevents the tightening nut 6 from rotating in the loosening direction, and the respective loosening protrusions 7a formed on the loosening member 7 are prevented. Since the contact area and contact resistance are increased due to the elastic deformation of ..., The tightening nut 6 can be positively prevented from rotating in the loosening direction, and it is possible to maintain a state in which they are firmly connected and fixed to each other for a long period of time. In addition, by integrally covering the loosening member 7 on the peripheral portion of the tightening nut 6 on the pressure contact side, the parts are not lost during assembly, and the parts can be easily handled and managed.

FIGS. 6 and 7 show an example in which a single loosening protrusion 7 b is continuously formed in the circumferential direction on the peripheral edge portion of the loosening member 7 on the pressure contact side, and the insertion hole 5 a formed in the crank arm 5 is formed. Facing the press-contact side peripheral portion, the press-contact side peripheral portion of the stopper member 7 is provided with a stopper protrusion 7b having an appropriate shape such as a quadrangular cross section, a trapezoidal cross section, or a semicircular cross section with respect to the circumferential direction. Are continuously formed. That is, by inserting the insertion portion 4a formed at one end of the crankshaft 4 into the insertion hole 5a formed at the base end of the crank arm 5, the screw formed at the insertion portion 4a of the crankshaft 4 is inserted. When the tightening nut 6 is screwed onto the shaft 4b and tightened, the locking member 7 covered with the tightening nut 6 is closely attached to the peripheral portion of the insertion hole 5a formed in the crank arm 5 on the pressure contact side without any gap. In addition, the elastic deformation of the loosening protrusion 7b formed on the loosening member 7 increases the contact area and the contact resistance, which can positively prevent the tightening nut 6 from rotating in the loosening direction. In addition, a single row of the loosening protrusions 7b having the same shape as the above-mentioned example may be partially formed in the circumferential direction on the pressure-contact side peripheral portion of the loosening member 7. The stop projection 7b is elastically deformed in the radial direction and the circumferential direction, and the contact area and contact resistance are increased. Moreover, the elasticity of the loosening protrusions 7b formed on the respective portions can prevent the tightening nut 6 from rotating in the loosening direction.

8 and 9, a plurality of (for example, four, six, eight) loosening protrusions 7c ... Are continuously formed in the circumferential direction on the pressure-contact side peripheral edge of the loosening member 7. Another example is shown, in which, for example, a trapezoidal cross section, a square cross section, and a semicircle cross section are provided on the pressure contact side peripheral edge of the locking member 7 so as to face the pressure contact side peripheral edge of the insertion hole 5a formed in the crank arm 5. A loosening protrusion 7c having an appropriate shape such as a shape and a triangular cross section is continuously formed in the circumferential direction. That is, the insertion portion 4a formed at one end of the crankshaft 4 and the insertion hole 5a formed at the base end of the crank arm 5 are fitted to each other to form the insertion portion 4a of the crankshaft 4. By tightening the tightening nut 6 by screwing it onto the screw shaft 4b, the locking member 7 covered with the tightening nut 6 is tightly adhered to the peripheral edge portion of the insertion hole 5a formed in the crank arm 5 on the pressure contact side. It Further, the elastic deformation of the respective loosening protrusions 7c formed on the loosening member 7 increases the contact area and the contact resistance, which can positively prevent the tightening nut 6 from rotating in the loosening direction.

FIG. 10 shows a plurality of loosening protrusions 7c (for example, 4, 6, 8) having the same shape as the above-mentioned example in the peripheral edge portion of the loosening member 7 in the circumferential direction in the circumferential direction. Another example of partial formation is shown, and similarly to the above example, the loosening protrusions 7c ... Formed on each part are elastically deformed in the radial direction and the circumferential direction, and the contact area and contact resistance increase. . Moreover, it is possible to prevent the tightening nut 6 from rotating in the loosening direction due to the elasticity of the respective loosening protrusions 7c formed on the respective portions.

FIG. 11 shows a bicycle crank arm coupling structure according to a second embodiment in which both axial end portions of the crank shaft 4 and the left and right crank arms 5, 5 are coupled and fixed by respective fastening bolts 8, 8. The loosening member 7 of the first embodiment described above is integrally formed on the pressure contact side peripheral edge of the tightening bolt 8 so as to face the pressure contact side peripheral edge of the insertion hole 5a formed in the crank arm 5.

That is, when the crankshaft 4 and the crank arm 5 are connected and fixed by the tightening bolt 8, the insertion portion 4 a formed at one end of the crankshaft 4 and the base end of the crank arm 5 are formed. As described in the first embodiment, the tightening bolt 8 is screwed into the screw hole 4c formed in the inserting portion 4a of the crank shaft 4 by fitting the tightening bolt 8 into the screw hole 5a. The tightening force causes the loosening member 7 to elastically deform, and the loosening member 7 covered with the tightening bolt 8 is closely attached to the peripheral edge of the insertion hole 5a formed in the crank arm 5 on the pressure contact side. It is possible to prevent looseness, looseness, and the like from occurring at the connecting portion between the crankshaft 4 and the crank arm 5. In addition, the elasticity of the loosening prevention member 7 can positively prevent the tightening bolt 8 from rotating in the loosening direction, and it is possible to maintain the state in which they are firmly connected and fixed to each other for a long period of time, and at the time of assembly. In addition, the parts can be handled and managed easily without being lost.

Further, by appropriately forming the number of the loosening protrusions 7b or the respective loosening protrusions 7c ... On the peripheral edge portion of the loosening member 7 covered with the tightening bolts 8 on the pressure contact side, the loosening protrusions are formed in the same manner as described above. The elastic deformations of 7b or the respective locking protrusions 7c ... Can firmly connect and fix each other.

FIGS. 12 and 13 show a connecting structure for a bicycle crank arm according to a third embodiment, in which a sheet-shaped loosening member 7 is fixed to the press-contact side peripheral edge of the tightening nut 6 and the tightening bolt 8. A sheet-like loosening member 7 is fixed by adhering or baking on the peripheral edge of the tightening nut 6 and the tightening bolt 8 facing the pressure contact side of the insertion hole 5 a formed in 5. That is, the tightening nut 6 is screwed into the screw shaft 4b formed in the insertion portion 4a of the crankshaft 4, or the screw bolt 4 is screwed into the screw hole 4c formed in the insertion portion 4a of the crankshaft 4. By tightening, as in the first embodiment, it is possible to prevent looseness or looseness from occurring at the connecting portion between the crankshaft 4 and the crank arm 5. In addition, the tightening nut 6 and the tightening bolt 8 are positively prevented from rotating in the loosening direction due to elastic deformation of the respective loosening projections 7a formed on the loosening member 7, and are firmly connected and fixed to each other. Can be maintained for a long time.

Further, by appropriately forming the number of the loosening protrusions 7b or the respective loosening protrusions 7c ... on the peripheral portion of the loosening member 7 fixed to the tightening nut 6 and the tightening bolt 8 on the pressure contact side, the first embodiment Similarly, by elastic deformation of the loosening protrusions 7b or the respective loosening protrusions 7c ..., They can be firmly connected and fixed to each other.

FIGS. 14 and 15 show a connecting structure for a bicycle crank arm according to a fourth embodiment, in which a ring-shaped loosening member 7 is fitted and fixed to the peripheral edge portions of the tightening nut 6 and the tightening bolt 8 on the pressure contact side. The annular nuts 6a, 8a having concave surfaces are formed on the peripheral edge portions of the tightening nut 6 and the tightening bolt 8 on the pressure contact side of the insertion hole 5a formed in the crank arm 5 so as to face the pressure contact side peripheral edge portion. A ring-shaped locking member 7 made of an appropriate elastic material such as synthetic rubber or synthetic resin is fitted into and fixed to the annular concave portions 6a, 8a of the fastening bolt 8 and the fastening bolt 8, respectively.

As shown in FIGS. 16 and 17, the above-mentioned loosening prevention member 7 is located on the outer peripheral side of the annular recesses 6 a, 8 a formed in the tightening nut 6 and the tightening bolt 8 on the pressing side peripheral edge of the loosening member 7. The protrusions are appropriately dimensioned to be fitted and fixed, and wedge-shaped loosening protrusions 7d ... Are circumferentially arranged at predetermined positions on the pressure-contact side peripheral edge of the loosening member 7 at appropriate positions (for example, 4 Locations, 6 locations). That is, the tightening nut 6 is screwed into the screw shaft 4b formed in the insertion portion 4a of the crankshaft 4, or the tightening bolt 8 is screwed into the screw hole 4c formed in the insertion portion 4a of the crankshaft 4. By tightening, as in the first embodiment, it is possible to prevent looseness, looseness, and the like from occurring in the connecting portion between the crankshaft 4 and the crank arm 5. Moreover, the elasticity of each of the loosening protrusions 7d formed on the loosening member 7 positively prevents the tightening nut 6 and the tightening bolt 8 from rotating in the loosening direction, and keeps them firmly connected to each other. Can be maintained for a period.

18 and 19 show a bicycle crank arm connection structure according to a fifth embodiment in which a ring-shaped loosening member 7 is fitted and fixed at the peripheral edge of the insertion hole 5a formed in the crank arm 5 on the pressure contact side. As shown, a concave annular recess 5b is formed at the peripheral edge of the insertion hole 5a formed in the crank arm 5 on the pressure contact side, and the locking member 7 of the fourth embodiment described above is fitted and fixed in the annular recess 5b. . That is, the tightening nut 6 is screwed into the screw shaft 4b formed in the insertion portion 4a of the crankshaft 4, or the screw bolt 4 is screwed into the screw hole 4c formed in the insertion portion 4a of the crankshaft 4. By tightening, similarly to the fourth embodiment, the loosening prevention member 7 is closely attached to the peripheral edge portions of the tightening nut 6 and the tightening bolt 8 on the pressure contact side, and the connecting portion between the crankshaft 4 and the crank arm 5 is secured. It is possible to prevent looseness, looseness, and the like from occurring. Moreover, the elasticity of the respective locking protrusions 7d formed on the locking member 7 positively prevent the tightening nut 6 and the tightening bolt 8 from rotating in the loosening direction, and firmly connect and fix them to each other. Can be maintained in a state for a long time.

In the correspondence between the configuration of the present invention and the above-described embodiment, the tightening member of the present invention corresponds to the tightening nut 6 and the tightening bolt 8 of the embodiment, and the annular recess of the tightening member is the same. Although it corresponds to the annular recess 6a of the tightening nut 6 and the annular recess 8a of the tightening bolt 8, the present invention is not limited to the configuration of the above-described embodiment.

In each of the above-described embodiments, the loosening protrusions 7a, 7b, 7c, 7d are formed on the peripheral edge portion of the loosening member 7 on the pressure contact side. However, for example, the fastening nut 6 and the tightening bolt 8 on the pressure contact side. The pressure-contact side peripheral portion of the loosening member 7 attached to the peripheral portion may be formed in a flat plane, and by tightening the tightening member 7 with the tightening nut 6 and the tightening bolt 8, the insertion hole 5a formed in the crank arm 5 is formed. Since the loosening prevention member 7 is pressed against the peripheral edge of the pressure contact side in a plane, the contact area and contact resistance are uniform, and the tightening nut 6 or the tightening bolt 8 can be prevented from rotating in the loosening direction.

In addition, a sheet-shaped loosening prevention member 7 may be adhesively fixed or baked and fixed to the peripheral edge portion of the insertion hole 5a formed in the crank arm 5 on the pressure contact side.

[Brief description of drawings]

FIG. 1 is a left side view showing a hanger portion of a bicycle.

FIG. 2 is a vertical cross-sectional front view showing a connection structure of hanger parts.

FIG. 3 is a cross-sectional view showing a connection structure of the first embodiment in which a locking member is covered with a tightening nut.

FIG. 4 is a bottom view showing a locking member having locking projections formed at four positions.

FIG. 5 is a vertical cross-sectional side view showing a protruding shape of a loosening protrusion.

FIG. 6 is a bottom view showing a loosening member in which a single loosening protrusion is continuously formed in the circumferential direction.

FIG. 7 is a vertical cross-sectional front view showing a protruding shape of a loosening protrusion.

FIG. 8 is a bottom view showing a locking member in which multiple locking projections are continuously formed in the circumferential direction.

FIG. 9 is a vertical cross-sectional front view showing a protruding shape of a loosening protrusion.

FIG. 10 is a bottom view of a loosening member in which loosening protrusions are partially formed in the circumferential direction.

FIG. 11 is a cross-sectional view showing a connecting structure of a second embodiment in which a tightening bolt is covered with a locking member.

FIG. 12 is a cross-sectional view showing a connection structure of a third embodiment in which a sheet-like loosening member is fixed to a tightening nut.

FIG. 13 is a cross-sectional view showing another connection structure in which a sheet-like loosening member is fixed to a tightening bolt.

FIG. 14 is a cross-sectional view showing a connection structure of a fourth embodiment in which a ring-shaped loosening member is fixed to a tightening nut.

FIG. 15 is a cross-sectional view showing another connection structure in which a ring-shaped loosening member is fixed to a tightening bolt.

FIG. 16 is a bottom view showing a ring-shaped loosening member having loosening protrusions formed at four positions.

FIG. 17 is a side view showing a protruding shape of a loosening protrusion.

FIG. 18 is a cross-sectional view showing a connecting structure of a fifth embodiment in which a ring-shaped loosening member is fixed to a crank arm side facing a tightening nut.

FIG. 19 is a cross-sectional view showing another connection structure in which a ring-shaped loosening member is fixed to the crank arm side facing the tightening bolt.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Bicycle 2 ... Frame main body 3 ... Hanger part 4 ... Crank shaft 4a ... Insert part 4b ... Screw shaft 4c ... Screw hole 5 ... Crank arm 5a ... Insert hole 5b ... Annular recess 6 ... Tightening nut 6a ... Annular recess 7 ... Loose Stop member 7a, 7b, 7c, 7d ... Loosening protrusion 8 ... Tightening bolt 8a ... Annular recess

Claims (9)

[Scope of utility model registration request] 1. A crankshaft is supported on a hanger portion of a frame body constituting a bicycle, and both shaft end portions of the crankshaft are protruded at both end side center portions of the hanger portion, and then both shaft end portions of the crankshaft. Each insertion part formed in,
For a bicycle in which each insertion hole formed at the base end of each crank arm is fitted respectively, and each tightening member is screwed and fixed to each insertion portion of the crankshaft protruding to the center of each insertion hole. A crank arm connecting structure, wherein a pressure contact side peripheral edge portion of a tightening member screwed into one side end portion of the crank shaft and a press contact side peripheral edge portion of an insertion hole formed at the base end portion of the crank arm are opposed to each other. A structure for connecting a crank arm for a bicycle, in which an elastic locking member is interposed between surfaces. 2. The connecting structure for a crank arm for a bicycle according to claim 1, wherein a slack preventing member is coated on a pressure contact side of the tightening member facing a pressure contact side peripheral portion of an insertion hole formed in the crank arm. 3. The bicycle crank arm connecting structure according to claim 1, wherein a slack preventing member is fixed to the pressure contact side of the tightening member facing the pressure contact side peripheral portion of the insertion hole formed in the crank arm. 4. The crank arm for a bicycle according to claim 1, wherein a loosening protrusion is provided on a peripheral edge portion of the loosening member on the pressure contact side to impart elasticity in a direction opposite to the loosening direction of the loosening member. Connection structure. 5. The bicycle crank arm coupling structure according to claim 1, wherein a proper number of loosening protrusions are formed in a circumferential direction on a peripheral edge portion of the loosening member on the pressure contact side. 6. An annular recess formed in either one of the pressure contact side peripheral edge of the insertion hole formed in the crank arm or the pressure contact side peripheral edge of the tightening member, and the annular recess formed in the one pressure contact side peripheral edge. 2. The bicycle crank arm connecting structure according to claim 1, wherein a ring-shaped loosening member is fitted and fixed to the ring-shaped member, and the press-contacting side peripheral edge portion of the loosening member is appropriately protruded outside the annular recess. 7. A loosening protrusion which gives elasticity in a direction opposite to the loosening direction of the loosening member is formed on the pressure-contact side peripheral edge portion of the loosening member protruding outward from the annular recess. 6. The bicycle crank arm connection structure according to 6. 8. The bicycle crank arm connecting structure according to claim 1, wherein the tightening member is a tightening nut that is screwed into a screw shaft formed in the insertion portion of the crankshaft. 9. The bicycle crank arm connecting structure according to claim 1, wherein the tightening member comprises a tightening bolt that is screwed into a screw hole formed in the insertion portion of the crankshaft.