Sprocket and transmission system

Abstract

A toothed disc and a transmission system, the transmission system comprises two toothed discs and a chain, the chain comprises a plurality of chain rollers, and a meshing space is formed between every two chain rollers. At least one of the toothed discs comprises a plurality of tooth-shaped structures, each of the tooth-shaped structures forms an arc surface meshing with the circumference of the chain roller, a driving surface extending outward from the arc surface, a slip surface opposite to the driving surface, and a tooth top surface connecting the driving surface and the slip surface, the connecting line between the centers of two adjacent arc surfaces is defined as a pitch diameter, the included angle between the slip surface and the pitch diameter is 45° to 55°, the arc surface has a cut-off point, a starting point connecting the driving surface, and a connecting point on a center connecting line connecting the center of the arc surface and the center of the toothed disc, a first arc length from the starting point to the connecting point is greater than a second arc length from the cut-off point to the connecting point, and the above design can improve the stability of meshing.

Description

Technical Field

[0001] The present invention relates to a transmission system, and in particular to a gear wheel and a transmission system used on a bicycle or a motorcycle. Background Art

[0002] See Figure 6 A conventional transmission system 4 for a bicycle or motorcycle typically includes two spaced-apart sprockets 41 (only a portion is shown enlarged in the figure) with a plurality of teeth 411 formed around their circumferences, and a chain 42 (only a portion is shown enlarged in the figure) that is engaged with the teeth 411 of the sprockets 41. The chain 42 includes a plurality of chain rollers 421, with an engagement space 422 formed between each pair of chain rollers 421 for the corresponding teeth 411 to engage.

[0003] Each latching tooth 411 includes an arcuate base region 412 and a radially outwardly extending protruding tooth region 413 connected to the base region 412. The base region 412 and the protruding tooth region 413 cooperate to form an arcuate surface 414 that engages with the chain roller 421, a driving surface 415 extending from the arcuate surface 414 toward the protruding tooth region 413, a run-off surface 416 facing away from the driving surface 415, and a tooth top surface 417 connecting the driving surface 415 and the run-off surface 416. The arcuate surface 414 is divided into two equal halves centered on a line L connecting the center O1 of the arcuate surface 414 and the center O2 of the toothed disc 41. The run-off surface 416 is mirror-symmetrical to the driving surface 415.

[0004] During transmission, due to the change in the rotation angle of the toothed disc 41, the chain roller 421 will gradually come into contact with the driving surface 415 and the arc surface 414 connected thereto, and during the loading process, there will be a sliding engagement between the arc surface 414 and the driving surface 415, which will disperse the loading force and make it less concentrated. Therefore, it is necessary to improve this. Summary of the Invention

[0005] An object of the present invention is to provide a toothed disc that overcomes at least one of the disadvantages of the prior art.

[0006] The toothed disc of the present invention is suitable for meshing and driving a chain, the chain including a plurality of chain rollers, a meshing space being formed between each two of the chain rollers, the toothed disc rotates along a transmission direction and includes a plurality of tooth-shaped structures, each of the tooth-shaped structures including a tooth bottom area for the corresponding chain roller to be embedded, and a convex tooth area protruding radially outward and capable of extending into the corresponding meshing space, the tooth bottom area and the convex tooth area cooperate to form an arc surface meshing with the circumference of the chain roller, a driving surface extending from the arc surface toward the convex tooth area, and a tooth area facing away from the driving surface. A slip surface that extends obliquely from the surface, and a tooth top surface connecting the driving surface and the slip surface, defining a centerline between the centers of two adjacent arc surfaces as a pitch diameter, an angle θ between the slip surface and the pitch diameter is 45° to 55°, the arc surface has a cutoff point, a starting point away from the cutoff point and connected to the driving surface, and a connecting point on a center line connecting the center of the arc surface and the center of the toothed disc, a first arc length from the starting point to the connecting point is greater than a second arc length from the cutoff point to the connecting point.

[0007] Furthermore, the convex portion of each outer waist segment has a wide inner side surface facing the outer engagement space and extending in a direction away from the other opposite outer waist segment, and the concave portion has a narrow inner side surface facing the outer engagement space and protruding in a direction toward the other opposite outer waist segment.

[0008] Furthermore, an included angle θ between the slip surface and the pitch diameter is 48° to 54°.

[0009] Furthermore, the arc length of the arc surface accounts for 27-35% of the total circumference of the arc surface.

[0010] Furthermore, the diameter of the arc surface is not less than the diameter of the chain roller.

[0011] Furthermore, the slip surface is an inclined straight surface, which extends inward from the tooth top surface and gradually tilts toward the arc surface of the other tooth-shaped structure.

[0012] Furthermore, the driving surface has a limiting protrusion connected to the starting point of the arc surface and protruding toward the transmission direction.

[0013] Furthermore, a transmission system comprises: two sprockets, arranged at intervals in front and behind, at least one of the sprockets being the sprocket described in the present invention; and a chain, in the shape of a closed ring and meshing around the sprockets, the chain comprising a plurality of chain rollers arranged at intervals along a length direction, a plurality of chain plates arranged on opposite sides of the chain rollers in an alternating manner, and a plurality of chain shafts respectively passing through the chain rollers and connecting the chain plates, with an engagement space formed between every two chain rollers.

[0014] Furthermore, the front toothed disc is the toothed disc described in the present invention, the slip surface of the toothed disc is inclined along the transmission direction, and the driving surface of each toothed structure is located in front of the slip surface along the transmission direction.

[0015] Furthermore, the toothed disc at the rear is the toothed disc described in the present invention, the slip surface of the toothed disc is inclined against the transmission direction, and the driving surface of each toothed structure along the transmission direction is located behind the slip surface.

[0016] An object of the present invention is to provide a transmission system that overcomes at least one of the disadvantages of the prior art.

[0017] The transmission system of the present invention comprises two sprockets and a chain. The sprockets are spaced apart in a front-to-rear manner, and at least one of the sprockets is as described above. The chain is in the form of a closed loop and meshes around the sprockets. The chain comprises a plurality of chain rollers spaced apart along a length, a plurality of chain plates staggered and arranged on opposite sides of the chain rollers, and a plurality of chain shafts passing through the chain rollers and connecting the chain plates. An engagement space is formed between every two chain rollers.

[0018] The present invention has the advantages that the shape design of the tooth structure can improve the stability of meshing, reduce the friction loss between the chain rollers, and achieve maximum power transmission with minimum energy loss, thereby reducing weight and improving transmission efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Other features and effects of the present invention will be clearly presented in the embodiments with reference to the accompanying drawings, in which:

[0020] Figure 1 is a side view schematically illustrating an embodiment of a transmission system of the present invention;

[0021] Figure 2 This is an incomplete exploded perspective view of the embodiment:

[0022] Figure 3 is a fragmentary, partially cut-away side view of the embodiment, illustrating a chain engaged with a sprocket;

[0023] Figure 4 is a fragmentary, partially cut-away side view of the embodiment, illustrating the chain about to engage with the sprocket;

[0024] Figure 5 is a fragmentary, partially cut-away side view of the embodiment, illustrating the chain about to be released from the chainring; and

[0025] Figure 6The present invention is an incomplete partial cross-sectional side view of a conventional chain, illustrating a state in which a chain is engaged with a toothed disc. DETAILED DESCRIPTION

[0026] See Figure 1 、 2 3. An embodiment of the transmission system of the present invention comprises two toothed discs 1 spaced apart from each other and each rotating in a transmission direction 10, and a chain 2 in the form of a closed loop that meshes around the toothed discs 1. The chain 2 is driven by the toothed discs 1 to move in a circular motion along a longitudinal direction 20, and comprises a plurality of chain rollers 21 spaced apart along the longitudinal direction 20, a plurality of chain plates 22 staggered in two rows and disposed on opposite sides of the chain rollers 21, and a plurality of chain shafts 23 passing through the chain rollers 21 and connecting the chain plates 22. An engagement space 24 is formed between every two chain rollers 21. Since the structure of the chain 2 is not the focus of the present invention, its shape and number of components may vary and are not limited to this embodiment.

[0027] The sprocket 1 includes a plurality of tooth-shaped structures 3 formed at equal intervals on the periphery. The number of tooth-shaped structures 3 of the sprocket 1 can be increased or decreased according to demand. Generally speaking, the sprocket 1 located at the front is a driving wheel, and the sprocket 1 located at the rear is a driven wheel. Moreover, at least one of the sprockets 1 is provided with the improved tooth-shaped structure 3 of the present invention. In this embodiment, the sprocket 1 located at the front is used as an example for explanation, but the implementation is not limited to this, and it can even be configured on multiple speed sprockets.

[0028] The tooth structures 3 are further described below. Each tooth structure 3 includes a tooth bottom region 31 for embedding the corresponding chain roller 21, and a protruding tooth region 32 that protrudes radially outward and can extend into the corresponding meshing space 24. The tooth bottom region 31 and the protruding tooth region 32 cooperate to form an arcuate surface 33 located within the tooth bottom region 31 and circumferentially meshing with the chain roller 21; a driving surface 34 extending from the arcuate surface 33 toward the protruding tooth region 32; a runaway surface 35 facing away from the driving surface 34 and connected to the arcuate surface 33 of the adjacent tooth structure 3; and a tooth top surface 36 located at the outer end and connecting the driving surface 34 and the runaway surface 35.

[0029] The arc length of the arc surface 33 accounts for 27-35% of the total circumference of the arc surface 33. The diameter of the arc surface 33 is no less than the diameter of the chain roller 21, which increases the contact ratio and ensures that the arc surface 33 is reliably and smoothly engaged with the circumference of the chain roller 21. The arc surface 33 has an end point 331 connecting the slip surface 35 of the adjacent tooth structure 3, a starting point 332, distal from the end point 331 and connected to the driving surface 34, and a connecting point 333 located on a line L connecting the center O1 of the arc surface 33 and the center O2 of the chain wheel 1. A first arc length S1 from the starting point 332 to the connecting point 333 is greater than a second arc length S2 from the end point 331 to the connecting point 333. The line connecting the centers O1 of two adjacent arc surfaces 33 is defined as a pitch diameter P.

[0030] The driving surface 34 has a limiting protrusion 341 connected to the starting point 332 of the arc surface 33 and protruding toward the transmission direction 10. The slip surface 35 is an inclined straight surface, which extends from the tooth top surface 36 inward to the arc surface 33 of the adjacent other tooth structure 3 and gradually extends in a direction away from the driving surface 34. The angle θ between the slip surface 35 and the pitch diameter P is 45° to 55°. Preferably, the angle θ between the slip surface 35 and the pitch diameter P is 48° to 54°. By designing the inclination angle of the slip surface 35, the arc length of the arc surface 33 is reduced, which is smaller than the conventional arc surface 414 (see Figure 6 ) arc length, and the second arc length S2 is smaller than the first arc length S1, and is also relatively smaller than the conventional arc surface 414 (see Figure 6 ) half the arc length, which can reduce weight.

[0031] It should be noted that, in design, the inclination direction of the slip surface 35 of the sprocket 1 located at the rear is opposite to that of the sprocket 1 located at the front, wherein the slip surface 35 of the sprocket 1 located at the front is inclined along the transmission direction 10, that is, the driving surface 34 of each tooth structure 3 along the transmission direction 10 is located in front of the slip surface 35, and the slip surface 35 of the sprocket 1 located at the rear is inclined against the transmission direction 10, that is, the driving surface 34 of each tooth structure 3 along the transmission direction 10 is located behind the slip surface 35, which can avoid the chain 2 from slipping in the rear section of the meshing area, and help to improve the tension maintenance of the chain 2, so as to achieve the maximum power transmission effect with minimal energy loss.

[0032] When in use, the toothed disc 1 rotates along the transmission direction 10 to engage and drive the chain 2 to move. Figure 4As shown, when the convex tooth area 32 of each tooth structure 3 extends into the corresponding meshing space 24, the limiting protrusion 341 first contacts the chain roller 21, and then drives the chain roller 21 to mesh with the arc surface 33 to gradually complete the meshing. By designing the limiting protrusion 341, the chain roller 21 can be contacted first during engagement and guided to the arc surface 33, thereby effectively shortening the impact and running-in during the initial engagement with the chain roller 21, reducing friction, reducing noise, and improving service life. Moreover, after the engagement is completed, the chain roller 21 can be more firmly engaged during transmission, allowing the chain roller 21 to maintain engagement in the arc surface 33, and not sliding between the driving surface 34 and the arc surface 33 due to changes in the rotation angle of the toothed disc 1. This will concentrate the load force, quickly transmit the power, and achieve maximum force transmission with minimal energy loss, thereby effectively achieving labor-saving transmission efficiency.

[0033] Then as Figure 5 As shown, when the chain roller 21 is about to disengage from the corresponding tooth structure 3, the chain roller 21 first gradually leaves the arc surface 33, then leaves the driving surface 34, and finally completely leaves the convex tooth area 32. During this process, compared with the conventional symmetrical convex tooth area 413 (indicated by the imaginary line), the present invention, through the inclined design of the slip surface 35, can not only form a larger space for the chain roller 21 to slide away smoothly, but also save material to achieve a lightweight function.

[0034] In summary, the sprocket and transmission system of the present invention primarily improve the shape of the tooth structure 3 of the sprocket 1, enabling the arc surface 33 to firmly engage with the chain roller 21 during load operation, thereby enhancing the stability of the engagement and ensuring good and reliable transmission performance. Furthermore, the beveled design of the slip surface 35 can reduce weight and increase transmission efficiency, thereby effectively achieving the objectives of the present invention.

[0035] However, the above is merely an embodiment of the present invention and should not be used to limit the scope of implementation of the present invention. All simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the content of the patent specification are still within the scope of the patent of the present invention.

Claims

1. A toothed disc, suitable for meshing and driving a chain, the chain comprising a plurality of chain rollers, a meshing space being formed between every two of the chain rollers, characterized in that: The toothed disc rotates along a transmission direction and includes a plurality of toothed structures, each of which includes a tooth bottom area for the corresponding chain roller to be embedded, and a convex tooth area that protrudes radially outward and can extend into the corresponding meshing space, the tooth bottom area and the convex tooth area cooperate to form an arc surface that meshes with the circumference of the chain roller, a driving surface extending from the arc surface toward the convex tooth area, a slip surface that is opposite to the driving surface and extends obliquely, and a tooth top surface connecting the driving surface and the slip surface, the slip surface is an inclined straight surface, which is from the tooth top surface inward and gradually toward the other toothed structure. The arc surface of the structure extends obliquely, and a centerline between the centers of two adjacent arc surfaces is defined as a pitch diameter. The angle θ between the slip surface and the pitch diameter is 45°~55°. The arc surface has a cutoff point, a starting point away from the cutoff point and connected to the driving surface, and a center point on a center line connecting the center of the arc surface and the center of the toothed disk. A first arc length from the starting point to the center point is greater than a second arc length from the cutoff point to the center point. The driving surface has a limiting convex portion connected to the starting point of the arc surface and protruding toward the transmission direction.

2. The toothed disc according to claim 1, characterized in that: The included angle θ between the slip surface and the pitch diameter is 48°~54°.

3. The toothed disc according to claim 1, characterized in that: The arc length of the arc surface accounts for 27-35% of the total circumference of the arc surface.

4. The toothed disc according to claim 1, characterized in that: The diameter of the arc surface is not less than the diameter of the chain roller.

5. A transmission system, characterized in that: Include: Two toothed discs, spaced apart from each other, at least one of the toothed discs being a toothed disc according to claim 1; and A chain is in the shape of a closed loop and meshed around the toothed discs. The chain includes a plurality of chain rollers arranged at intervals along a length direction, a plurality of chain plates arranged alternately on two opposite sides of the chain rollers, and a plurality of chain shafts respectively passing through the chain rollers and connecting the chain plates, and a meshing space is formed between every two chain rollers.

6. The transmission system according to claim 5, characterized in that: The toothed disc located in the front is the toothed disc as claimed in claim 1, the slip surface of the toothed disc is inclined along the transmission direction, and the driving surface of each toothed structure along the transmission direction is located in front of the slip surface.

7. The transmission system according to claim 5, characterized in that: The toothed disc at the rear is the toothed disc as claimed in claim 1 , the slip surface of the toothed disc is inclined against the transmission direction, and the driving surface of each toothed structure along the transmission direction is located behind the slip surface.

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