TWI898495B - Thick and thin gear plates - Google Patents

Abstract

A thick-thin gear plate comprises a plate unit, a thin gear unit, and a thick gear unit. The thin gear unit includes a plurality of thin protruding teeth, a plurality of front tooth bases and a plurality of rear tooth bases arranged alternately between the thin protruding teeth, a thin tooth back surface flush with a rear surface of the plate unit, and a thin tooth front surface. Each thin protruding tooth has a driving surface, a slip surface asymmetrical in shape to the driving surface, and a tooth top surface. Each rear tooth base has a first chamfer connecting to the thin tooth front surface and a second chamfer connecting to the thin tooth back surface. The thick tooth unit includes several thick teeth and several grooves connecting the thick teeth. Each thick tooth is integrally formed on the front surface of the thin tooth behind the rear tooth base. The width of the thick tooth is equal to the width of the groove, and the thickness of the thick tooth accounts for 30-50% of the thickness of the thin tooth. The present invention can achieve a guiding and correction effect when transmitting a chain.

Description

Thick and thin gear plates

The present invention relates to a gear, and in particular to a thick-thin gear for use in bicycles or motorcycles.

A conventional transmission system for a bicycle or motorcycle typically includes at least two gears spaced apart front and rear, and a chain wound around the gears. Each gear includes several teeth formed around its periphery. The chain comprises several inner links, several outer links, several rollers positioned between the inner links, and several axles connecting the inner and outer links. The inner links and the rollers define several interlocking spaces.

During transmission, the gear plate rotates in a transmission direction to engage and drive the chain. However, because the gear plate lacks any guide design, the protruding teeth easily collide with or even get stuck on the ends of the inner chain plates when engaging the engagement space, resulting in an unusual sound and even preventing smooth insertion and engagement. Therefore, improvement is needed.

Therefore, an object of the present invention is to provide a thick-thin gear disc that can overcome at least one of the shortcomings of the prior art.

Therefore, the thick-thin gear disc of the present invention rotates in a transmission direction and includes a disc unit, a thin gear unit, and a thick gear unit.

The disk unit includes a disk back surface and a disk front surface spaced apart from each other.

The thin tooth unit is arranged along the periphery of the disc unit and includes a plurality of thin protruding teeth, a plurality of front tooth bottoms and a plurality of rear tooth bottoms arranged in a staggered manner and connected between the thin protruding teeth, a thin tooth back surface that is flush with the disc back surface and on the same plane, and a thin tooth front surface opposite to the thin tooth back surface. Each of the thin protruding teeth has a driving surface along the transmission direction, a A slip surface opposite to the transmission direction, and a tooth top surface located on the top side and connecting the driving surface and the slip surface. The driving surface has a front rounded corner portion that is smoothly connected to the tooth top surface. The driving surface and the slip surface are asymmetrical in shape. Each rear tooth bottom has a first chamfer connected to the front surface of the thin tooth, and a second chamfer connected to the back surface of the thin tooth and corresponding to the first chamfer.

The thick tooth unit is arranged along the periphery of the disc unit and includes a plurality of thick protruding teeth and a plurality of grooves connecting the thick protruding teeth. Each thick protruding tooth is arranged on the thin protruding tooth behind the rear tooth base and is integrally formed on the front surface of the thin tooth of the thin tooth unit. The width of the thick protruding tooth is equal to the width of the groove, and the thickness of each thick protruding tooth accounts for 30-50% of the thickness of the thin protruding tooth.

The effectiveness of this invention is that the above-mentioned design can increase the stability of the engagement with the chain, thereby improving transmission efficiency.

10: Axis

11: Transmission direction

2: Disk unit

21: Back of the disk

22: Front of the disk

3: Thin tooth unit

31: Thin convex teeth

311: Driving surface

312: Slip surface

313: Top of tooth

314: Back of tooth tip

315: Front of tooth tip

316: Front rounded corner

317: Rear rounded corner

318: Limiting convex part

32: Front tooth bottom

33: Posterior tooth bottom

331: First Chamfer

332: Second chamfer

35: Back of thin teeth

36: Thin teeth front

4: Thick tooth unit

41: Thick protruding teeth

411: Top Edge

42: Thick Teeth

43: Groove

44: Thick teeth front

O: Center of circle

P: Node diameter

θ: Indentation Angle

9: Chain

91: Inner link

911: Inner link

912: Chain

913: Incline guide part

92: External link

921: Outer chain link

922: Chain

93: Merging Space

Other features and functions of the present invention will be clearly presented in the embodiments with reference to the accompanying drawings, in which: FIG1 is a perspective view illustrating a first embodiment of the thick-thin gear plate of the present invention; FIG2 is a fragmentary enlarged perspective view illustrating the first embodiment; FIG3 is a fragmentary enlarged front view illustrating the first embodiment; FIG4 is a fragmentary enlarged rear view illustrating the first embodiment; FIG5 is a cross-sectional view taken along line V-V in FIG3; FIG6 is a fragmentary exploded cross-sectional view illustrating the first embodiment engaged with a chain; FIG7 is a fragmentary enlarged perspective view illustrating a second embodiment of the thick-thin gear plate of the present invention; and FIG8 is a fragmentary enlarged front view illustrating the second embodiment.

Before the present invention is described in detail, it should be noted that similar components are represented by the same reference numerals in the following description.

Referring to Figure 1, a first embodiment of the thick-thin gear of the present invention is applied to a transmission system of a bicycle or motorcycle and is rotatable about an axis 10 in a transmission direction 11. The thick-thin gear comprises a disc unit 2, a thin tooth unit 3, and a thick tooth unit 4.

Referring to Figures 2 to 5, the disk unit 2 is generally in the shape of a circular flat plate and includes a disk back surface 21 and a disk front surface 22 spaced apart from each other.

The thin tooth unit 3 is arranged along the periphery of the disc unit 2 and includes a plurality of thin teeth 31 arranged at equal angles, a plurality of front tooth bases 32 and a plurality of rear tooth bases 33 arranged in a staggered manner and connected between the thin teeth 31, a plurality of thin tooth back surfaces 35 formed by the thin teeth 31 and aligned with the disc back surface 21 and located on the same plane, and a thin tooth front surface 36 opposite the thin tooth back surface 35.

Each of the thin tooth 31 has a driving surface 311 along the transmission direction 11, a slip surface 312 opposite to the transmission direction 11 and asymmetrical in shape with the driving surface 311, a tooth top surface 313 located on the top side and connecting the driving surface 311 and the slip surface 312, a tooth tip back surface 314 extending from an edge curve of the tooth top surface 313 to the thin tooth back surface 35, and a tooth tip front surface 315 extending from the other edge curve of the tooth top surface 313 to the thin tooth front surface 36. The driving surface 311 has a front rounded corner 316 that smoothly connects to the tooth top surface 313. The radius of the front rounded corner 316 is approximately 6-14 mm. The release surface 312 has a rear rounded corner 317 that smoothly connects to the tooth top surface 313. The radius of the rear rounded corner 317 is approximately 2-6 mm. The front tooth bottom 32 is located on the front side of the thin tooth 31 in the transmission direction 11, while the rear tooth bottom 33 is located on the opposite side. Each rear tooth bottom 33 has a first chamfer 331 connected to the front face 36 of the thin tooth and a second chamfer 332 connected to the back face 35 of the thin tooth and corresponding to the first chamfer 331. The angles of the first chamfer 331 and the second chamfer 332 are approximately 15° to 45°, preferably 15° to 40°.

The thick tooth unit 4 is disposed along the periphery of the disc unit 2 and includes a plurality of thick protruding teeth 41 arranged at equal angles, a plurality of thick tooth bases 42 connecting the equally thick protruding teeth 41, a plurality of grooves 43 defined by the equally thick protruding teeth 41 and the equally thick tooth bases 42, and a thick tooth front face 44 aligned and coplanar with the disc front face 22. Each thick protruding tooth 41 is disposed on the thin protruding tooth 31 behind the rear tooth base 33 and is integrally formed with the thin tooth front face 36. The thick tooth 41 has a top edge 411 that is lower than the tooth top surface 313 of the thin tooth 31. The width of the top edge 411 decreases obliquely toward the tooth top surface 313 and smoothly connects to the tooth tip front surface 315. Viewed along the transmission direction 11, the thickness of the thick tooth 41 accounts for 30-50% of the thickness of the thin tooth 31. Viewed along the axis 10, the width of the thick tooth 41 is equal to the width of the groove 43. In other words, the distance between the thick tooth front surface 44 and the thin tooth front surface 36 is equal to the width of the groove 43.

Referring to Figures 2, 5, and 6, during use, the thick and thin gears rotate along the transmission direction 11, adapted to engage and drive a chain 9. The chain 9 comprises a plurality of interlocking inner links 91 and a plurality of outer links 92. Each inner link 91 has two parallel inner links 911 and two spaced rollers 912 disposed between the inner links 911. Each inner link 911 has two inclined guides 913 formed on the inner side of each end. Each outer link 92 has two parallel outer links 921 staggered between the outer sides of the two inner links 91, and two chain shafts 922 spaced apart and connecting the outer links 921 and the inner links 911. A space 93 is defined between the inner links 911 and the chain rollers 912.

During the operation of the thick-thin gear disc, the thin teeth 31 and the thick teeth 41 engage the engaging spaces 93. During engagement, the first chamfers 331 and the second chamfers 332 contact the corresponding beveled guides 913 of the inner link 911, ensuring a secure engagement and preventing wear and tear on the chain 9 due to deviation. This reduces any unwanted noise during engagement. Furthermore, the thick teeth 41 contact the inner side of the corresponding outer link 921, guiding the chain 9 in advance and enhancing engagement strength and stability. This prevents chain drop and ensures smoother transmission.

7 and 8 , the structure of a second embodiment of a thick-thin gear plate of the present invention is substantially the same as that of the first embodiment, with the difference being that the driving surface 311 of each thin tooth 31 has a limiting protrusion 318 connected to the rear tooth bottom 33 or the front tooth bottom 32 and protruding toward the transmission direction 11 . The design of the stopper protrusion 318 allows it to preemptively contact the chain roller 912 during engagement, guiding the chain roller 912 to the corresponding front tooth bottom 32 or rear tooth bottom 33. This effectively reduces the impact and running-in during initial engagement with the chain roller 912, thereby reducing friction, lowering noise, and increasing service life. Furthermore, during transmission, the gears engage more securely with the chain roller 912, effectively achieving efficient and labor-saving transmission.

Furthermore, the slip surface 312 of the second embodiment is an inclined straight surface, extending gradually from the tooth top surface 313 toward the rear tooth bottom 33. The line connecting the centers O of the two adjacent front tooth bottoms 32 and rear tooth bottoms 33 is defined as a pitch diameter P. The angle θ between the slip surface 312 and the pitch diameter P is 45° to 55°, with a preferred angle θ between the slip surface 312 and the pitch diameter P being 48° to 54°. The angled bevel design of the sliding surface 312 not only creates a larger space for the roller 912 to slide smoothly, but also saves material, achieving a lightweight design.

In summary, the thick and thin gear design of the present invention can provide a guiding and correcting effect, improve the stability of the engagement with the chain 9, reduce friction noise, and improve transmission efficiency, thus truly achieving the purpose of this invention.

However, the above descriptions are merely examples of the present invention and should not be construed to limit the scope of the present invention. Any simple equivalent variations and modifications made within the scope of the patent application and the contents of the patent specification are still covered by the present patent.

11: Transmission direction

2: Disk unit

22: Front of the disk

3: Thin tooth unit

31: Thin convex teeth

311: Driving surface

312: Slip surface

313: Top of tooth

314: Back of tooth tip

315: Front of tooth tip

316: Front rounded corner

317: Rear rounded corner

32: Front tooth bottom

33: Posterior tooth bottom

331: First Chamfer

36: Thin teeth front

4: Thick tooth unit

41: Thick protruding teeth

411: Top Edge

42: Thick Teeth

43: Groove

44: Thick teeth front

Claims (10)

A thick-thin gear disc rotates in a transmission direction and comprises: a disc unit comprising a disc back surface and a disc front surface spaced apart from each other; a thin tooth unit disposed along the periphery of the disc unit and comprising a plurality of thin protruding teeth, a plurality of front tooth bottoms and a plurality of rear tooth bottoms arranged in a staggered manner and connected between the thin protruding teeth, a thin tooth back surface aligned with the disc back surface and on the same plane, and a thin tooth front surface opposite to the thin tooth back surface, each of the thin protruding teeth having a driving surface along the transmission direction and an anti-locking surface. A sliding surface extending in the transmission direction, and a tooth top surface located on the top side and connecting the driving surface and the sliding surface. The driving surface has a front rounded corner portion that is smoothly connected to the tooth top surface. The driving surface and the sliding surface are asymmetrical in shape. Each rear tooth bottom has a first chamfer connected to the front surface of the thin tooth, and a second chamfer connected to the back surface of the thin tooth and corresponding to the first chamfer; and A thick tooth unit is disposed along the periphery of the disc unit and includes a plurality of thick protruding teeth and a plurality of grooves connecting the thick protruding teeth. Each of the thick protruding teeth is disposed on the thin protruding teeth behind the rear tooth base and is integrally formed on the front surface of the thin tooth of the thin tooth unit. The width of the thick protruding teeth is equal to the width of the grooves, and the thickness of each thick protruding tooth accounts for 30-50% of the thickness of the thin protruding teeth. The thick-thin gear disc as described in claim 1, wherein the thick-tooth unit further includes a thick-tooth front surface that is flush with the front surface of the disc body and located on the same plane, and the distance between the thick-tooth front surface and the thin-tooth front surface is equal to the width of the groove. The thick-thin gear disc as described in claim 1, wherein the radius of the front rounded corner portion of the driving surface is 6-14 mm. The thick-thin gear plate as described in claim 1, wherein the angle of the first chamfer is 15°~40°, and the angle of the second chamfer is 15°~40°. The thick-thin tooth plate as described in claim 1, wherein the thick protruding tooth has a top edge, the top edge is lower than the tooth top surface of the thin protruding tooth, and extends obliquely and descendingly toward the tooth top surface. The thick-thin gear plate as described in claim 1 or 3, wherein each of the slip-off surfaces has a rear fillet portion that is smoothly connected to the tooth top surface, and the radius of the rear fillet portion is 2-6 mm. The thick-thin gear plate as described in claim 1, wherein the slip surface is an inclined straight surface that gradually extends from the tooth top surface toward the rear tooth bottom. The thick-thin gear plate as described in claim 7, wherein a centerline connecting the centers of the two adjacent front tooth bottoms and the rear tooth bottoms is defined as a pitch diameter, and an angle between the slip surface and the pitch diameter is 45° to 55°. The thick-thin gear disc as described in claim 8, wherein the angle between the slip surface and the pitch diameter is 48°-54°. As described in claim 1, the thick-thin gear plate, wherein the driving surface has a limiting protrusion connected to the rear tooth bottom or the front tooth bottom and protruding toward the transmission direction.