WO2021189301A1

WO2021189301A1 - Spline crank structure

Info

Publication number: WO2021189301A1
Application number: PCT/CN2020/081135
Authority: WO
Inventors: 徐金兴
Original assignee: 徐金兴
Priority date: 2020-03-25
Filing date: 2020-03-25
Publication date: 2021-09-30

Abstract

Disclosed is a spline crank structure, comprising a central shaft (10) and cranks (20) arranged at two ends of the central shaft (10), wherein external splines (11) for assembling the cranks (20) are arranged on two ends of the central shaft (10), the radii of the external splines (11) are tapered from the middle of the central shaft (10) to the ends of the central shaft (10), and the ends of the external splines (11) close to the central shaft (10) are connected to an outer surface of the central shaft (10); and internal splines (21) matching the external splines (11) are arranged at the ends of the cranks (20). According to the spline crank structure, the radii of the external splines of the central shaft are configured to be tapered from the middle of the central shaft to the end of the central shaft, such that after the cranks are installed and locked on the external splines, the cranks are closely fitted to the external splines, and the contact area and installation stability of the cranks and the external splines are increased, thereby preventing loosening; and the structural strength and the torsion between the cranks and the central shaft can also be improved, thereby prolonging the service life of a product.

Description

A spline crank structure

Technical field

The invention relates to the field of bicycle parts, in particular to a spline crank structure.

Background technique

Bicycles, also known as bicycles or bicycles, are usually small two-wheeled land vehicles. After a person rides on the car, he uses his foot on the pedal as the driving force, which is a green and environmentally friendly means of transportation. English bicycle. Among them, bi means two, and cycle means wheel, that is, a two-wheeled vehicle. In Mainland China, Taiwan, and Singapore, they are usually called "bicycles" or "bicycles"; in Hong Kong and Macau, they are usually called "bicycles" (in fact, they are usually called in Cantonese); and in Japan they are called "self-spin (turn) bikes" ". There are many types of bicycles, including ordinary bicycles, road bicycles, exercise bicycles, mountain singles and so on.

The crank structure is an important part of the bicycle, which connects the chainring and the pedals. The crank and the bottom bracket of the existing bicycle crank structure are mostly assembled through splines and shaft holes, and the shaft holes are straight holes. To facilitate assembly, the shaft holes are slightly larger than the splines, so that there is a gap between the two , Resulting in a certain degree of looseness. After the product is used for a long time, it is easy to cause the pedal to shake and affect the user experience.

technical problem

The purpose of the present invention is to provide a spline crank structure, which improves the stability and strength of the structure so as to prolong the service life of the product.

Technical solutions

In order to achieve the above objective, the solution of the present invention is:

A spline crank structure includes a central shaft and cranks arranged at both ends of the central shaft; wherein both ends of the central shaft are provided with external splines for the crank to be assembled, and the radius of the external splines is along the The middle portion of the bottom bracket gradually decreases toward the end of the bottom bracket, and the end of the external spline close to the bottom bracket is connected to the outer surface of the bottom bracket; the end of the crank is provided with An inner spline that matches the outer spline.

The external spline includes a number of concave surfaces uniformly arranged along the circumferential direction of the external spline, and a number of edge surfaces connected between adjacent concave surfaces. The outer surface of the shaft.

The edge surface gradually narrows along the middle part of the middle shaft toward the end part of the middle shaft.

The number of the concave surfaces is at least three.

A foolproof structure is arranged between the outer spline and the inner spline.

The foolproof structure is embodied in that the external spline has at least one special concave surface with a curvature different from other concave surfaces.

The crank is installed at the end of the bottom bracket through a plug screw.

An end of the external spline away from the middle part of the central shaft is provided with a first mounting part for assembling the plugging screw.

The first mounting part is an external thread or an internal thread for assembling the plugging screw.

The connection between the external spline and the middle part of the central shaft is provided with a second mounting portion, and a chainring and a locking member for locking the chainring are mounted on the outer periphery of the second mounting portion.

The second mounting portion is an external thread provided on the outer circumference of the bottom bracket, and an end of the second mounting portion close to the center portion of the bottom bracket is provided with embossing; the locking member is provided with the second A mounting hole matching the mounting part; the chain ring is provided with a through hole matching the embossing; the second mounting part penetrates the through hole, and the locking member is threadedly connected with the second mounting part And pressing the chain ring to fit on the embossing.

The peripheral edge of the through hole is provided with a ring of flange protruding in the direction of the locking member, the peripheral edge of the mounting hole is formed with a relief step corresponding to the flange, and the locking member is attached to the tooth And the flange is fitted in the relief step.

Beneficial effect

After adopting the above technical solution, the present invention sets the radius of the outer spline of the central shaft so that the middle part of the central shaft gradually decreases toward the end of the central shaft, so that the crank is installed on the external spline and locked, and then forms with the external spline. Tight fitting installation improves the contact area and installation stability of the two, thereby avoiding looseness, and can increase the structural strength, as well as the torsion between the crank and the bottom shaft, so as to extend the service life of the product.

Description of the drawings

Figure 1 is a perspective view of a specific embodiment of the present invention;

Figure 2 is an exploded view of a specific embodiment of the present invention;

Figure 3 is a front view of a crank of a specific embodiment of the present invention;

Figure 4 is a front view of a shaft in a specific embodiment of the present invention;

Figure 5 is a side view of the shaft in a specific embodiment of the present invention;

Description with reference signs: bottom bracket 10; external spline 11; concave surface 111; edge surface 112; first mounting part 12; second mounting part 13; embossing 14; crank 20; internal spline 21; chain plate 30; Hole 31; flange 32; locking member 40; mounting hole 41;

Embodiments of the present invention

In order to further explain the technical solution of the present invention, the present invention will be described in detail below through specific embodiments.

The present invention is a spline crank structure, which includes a central shaft 10 and cranks 20 arranged at both ends of the central shaft 10.

Wherein, both ends of the central shaft 10 are provided with external splines 11 for the crank 20 to assemble. The radius of the external splines 11 gradually decreases from the middle of the central shaft 10 to the end of the central shaft 10, and the external splines 11 are close to One end of the bottom bracket 10 is connected to the outer surface of the bottom bracket 10; the end of the crank 20 is provided with an internal spline 21 matching the external spline 11.

Referring to Figs. 1 to 5, specific embodiments of the present invention are shown.

The above-mentioned external spline 11 includes a plurality of concave surfaces 111 uniformly arranged along the circumferential direction of the external spline 11, and a plurality of edge surfaces 112 connected between adjacent concave surfaces 111. The end of the edge surface 112 close to the middle of the central shaft 10 is connected to the central shaft 10.的外面。 The outer surface. The concave surface 111 can increase the contact area between the external spline 11 and the internal spline 21, thereby achieving the purpose of increasing the bearing, torque, and strength of the bottom bracket 10; compared with the traditional bottom bracket 10, the bottom bracket 10 of the present invention can Instead of a thicker traditional mandrel, the purpose of saving materials is achieved; at the same time, the connection of the ridge 112 to the outer surface of the central shaft 10 can also avoid faults, greatly reducing the rate of defective products in the production process (referring to the formation of external splines At 11 o'clock, the connection between the external spline 11 and the body of the bottom bracket 10 is broken).

The above-mentioned edge surface 112 gradually narrows from the center of the center shaft 10 to the end of the center shaft 10, so that the edge surface 112 is trapezoidal, which can ensure that the center shaft 10 and the crank 20 are assembled tighter and improve the accuracy of assembly.

The number of the aforementioned concave surfaces 111 is at least three.

A foolproof structure is provided between the above-mentioned outer spline 11 and the inner spline 21 to facilitate the rapid positioning and installation of the bottom bracket 10 and the crank 20 and improve the installation efficiency.

The above-mentioned foolproof structure is embodied that the above-mentioned outer spline 11 has at least one special concave surface 111' with a curvature different from that of other concave surfaces 111. In this embodiment, this special concave surface 111' is a flat surface.

The crank 20 is installed at the end of the bottom bracket 10 by a plug screw (not shown in the figure), and this assembly method is also commonly used in the art.

An end of the external spline 11 away from the middle of the central shaft 10 is provided with a first mounting portion 12 for assembling a plug screw. In this embodiment, the first installation part 12 is an external thread for assembling the plugging screw; in practical applications, according to different installation environments and requirements, the first installation part 12 may also be an internal thread.

The connection between the external spline 11 and the middle part of the central shaft 10 is provided with a second mounting portion 13, and a chainring 30 and a locking member 40 for locking the chainring 30 are mounted on the outer periphery of the second mounting portion 13. Therefore, the crankset 30 and the central shaft 10 are detachable and installable, and each part of the present invention can be produced and formed separately, and it is convenient to store after disassembly, which saves storage space and reduces transportation costs. In this embodiment, the second mounting portion 13 is an external thread provided on the outer circumference of the center shaft 10, and the end of the second mounting portion 13 close to the center of the center shaft 10 is provided with embossing 14; the locking member 40 is provided with a second mounting The mounting hole 41 that matches the part 13 means that the mounting hole 41 has an internal thread that matches the external thread of the second mounting part; the chain ring 30 is provided with a through hole 31 that matches the embossing 14; the second mounting part 13 penetrates Set in the through hole 31, the locking member 40 is threadedly connected with the second mounting portion 13 and the pressing ring 30 is fitted on the embossing 14. In addition, the assembling method of the pressure plate and the central shaft 10 also includes, but is not limited to, direct threaded fit between the pressure plate and the second mounting portion 13.

The peripheral edge of the through hole 31 is provided with a ring of flange 32 protruding in the direction of the locking member 40, the peripheral edge of the mounting hole 41 is formed with a step 42 corresponding to the flange 32, and the locking member 40 is attached to the chainring 30 and The flange 32 is fitted in the relief step 42 to realize the positioning and installation of the locking member 40 and the chainring 30, thereby improving installation efficiency and accuracy, and structural stability.

Through the above structure, the present invention sets the radius of the outer spline 11 of the center shaft 10 so that the middle of the center shaft 10 gradually decreases toward the end of the center shaft 10, so that the crank 20 is installed on the outer spline 11 and locked, and The external spline 11 forms a tight fitting installation, which improves the contact area and installation stability of the two, thereby avoiding looseness, and can increase the structural strength and the torsion force between the crank 20 and the central shaft 10 to prolong the service life of the product.

The foregoing embodiments and drawings do not limit the product form and style of the present invention, and any appropriate changes or modifications made by those of ordinary skill in the art should be regarded as not departing from the patent scope of the present invention.

Claims

A spline crank structure, characterized in that it comprises a central shaft and cranks arranged at both ends of the central shaft;

Wherein, both ends of the bottom bracket are provided with external splines for assembling the crank, and the radius of the external splines gradually decreases along the middle of the bottom bracket toward the ends of the bottom bracket, and The end of the external spline close to the central shaft is connected to the outer surface of the central shaft; the end of the crank is provided with an internal spline matching the external spline.
The spline crank structure according to claim 1, wherein:

The external spline includes a number of concave surfaces uniformly arranged along the circumferential direction of the external spline, and a number of edge surfaces connected between adjacent concave surfaces. The outer surface of the shaft.
The spline crank structure according to claim 2, characterized in that:

The edge surface gradually narrows along the middle part of the middle shaft toward the end part of the middle shaft.
The spline crank structure according to claim 2, characterized in that:

The number of the concave surfaces is at least three.
The spline crank structure according to claim 2, characterized in that:

A foolproof structure is arranged between the outer spline and the inner spline.
A spline crank structure according to claim 5, characterized in that:

The foolproof structure is embodied in that the external spline has at least one special concave surface with a curvature different from other concave surfaces.
The spline crank structure according to claim 1, wherein:

The crank is installed at the end of the bottom bracket through a plug screw.
A spline crank structure according to claim 7, characterized in that:

An end of the external spline away from the middle part of the central shaft is provided with a first mounting part for assembling the plugging screw.
A spline crank structure according to claim 8, characterized in that:

The first mounting part is an external thread or an internal thread for assembling the plugging screw.
The spline crank structure according to claim 1, wherein:

The connection between the external spline and the middle part of the central shaft is provided with a second mounting portion, and a chainring and a locking member for locking the chainring are mounted on the outer periphery of the second mounting portion.
The spline crank structure of claim 10, wherein:

The second mounting portion is an external thread provided on the outer circumference of the bottom bracket, and an end of the second mounting portion close to the center portion of the bottom bracket is provided with embossing; the locking member is provided with the second A mounting hole matching the mounting part; the chain ring is provided with a through hole matching the embossing; the second mounting part penetrates the through hole, and the locking member is threadedly connected with the second mounting part And pressing the chain ring to fit on the embossing.
The spline crank structure of claim 11, wherein:

The peripheral edge of the through hole is provided with a ring of flange protruding in the direction of the locking member, the peripheral edge of the mounting hole is formed with a relief step corresponding to the flange, and the locking member is attached to the tooth And the flange is fitted in the relief step.