Transmission and saddle-riding type vehicle including the same

Abstract

To provide a transmission capable of easily preventing coming-off of a circlip and a saddle-riding type vehicle including the transmission.SOLUTION: A transmission 30 includes an output shaft 43, a second gear 45 and a circlip 46. The output shaft 43 includes a groove part 43a. The second gear 45 includes a through hole B for inserting the output shaft 43. The second gear 45 is supported by the output shaft 43. The circlip 46 is fitted into the groove part 43a. The circlip 46 regulates movement of the second gear 45 in an axial direction C of the output shaft 43 relative to the output shaft 43. The circlip 46 has a cross section 46b. The cross section 46b of the circlip 46 has a circular shape.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a transmission and a straddle-type vehicle equipped with the same. [Background technology]

[0002] Patent Document 1 discloses an assembly. The assembly includes a shaft, a component, a groove, and a retaining ring. The groove is formed in the shaft. A retaining ring is fitted into the groove. The retaining ring is, for example, a circlip. The circlip has a rectangular cross section. The component contacts the circlip. The circlip restricts relative movement between the shaft and the component in the axial direction. The component applies a thrust load to the circlip. The thrust load is also called an axial load. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5805392 Summary of the Invention [Problem to be solved by the invention]

[0004] The cross section of the circlip is rectangular. Therefore, the circlip easily deforms the groove. For example, when a thrust load acts on the circlip, the circlip easily deforms the groove. If the groove is deformed, the circlip easily comes off the groove.

[0005] The present invention has been made in view of the above circumstances, and has as its object to provide a transmission that can easily prevent circlips from coming off, and a saddle-type vehicle equipped with the same. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention has the following configuration. That is, the present invention is a transmission, a shaft portion having a groove; a gear having a through hole for inserting the shaft portion and supported by the shaft portion; a circlip that is fitted into the groove and restricts movement of the gear relative to the shaft in the axial direction of the shaft; Equipped with The circlip has a circular cross section. It is a transmission.

[0007] The transmission includes a shaft, a gear, and a circlip. The shaft has a groove. The gear has a through hole for inserting the shaft. The gear is supported on the shaft. The circlip is fitted into the groove. The circlip restricts movement of the gear relative to the shaft in the axial direction of the shaft.

[0008] The circlip has a cross section. The cross section of the circlip is circular. Therefore, the circlip does not easily deform the groove. Even when the gear hits the circlip, the circlip does not easily deform the groove. Therefore, the circlip does not easily come off the groove. In other words, it is easy to prevent the circlip from coming off the groove. Therefore, it is easy for the circlip to restrict the movement of the gear described above.

[0009] In summary, in this transmission, it is easy to prevent the circlip from coming off, and therefore it is easy to restrict the gear from moving relative to the shaft in the axial direction of the shaft.

[0010] In the above-mentioned transmission, When the circlip is fitted into the groove, it is preferable that at least half of the circlip is housed in the groove.

[0011] Therefore, it is even easier to prevent the circlip from coming out of the groove.

[0012] In the above-mentioned transmission, It is preferable that the depth of the groove is 50% or more of the diameter of the cross section of the circlip and is less than the diameter of the cross section of the circlip.

[0013] The depth of the groove is 50% or more of the diameter of the cross section of the circlip. Therefore, it is easy to accommodate more than half of the circlip in the groove. The depth of the groove is less than the diameter of the cross section of the circlip. Therefore, it is impossible for the groove to accommodate the entire circlip. Therefore, when the circlip is fitted into the groove, a part of the circlip always protrudes from the groove. When the circlip is fitted into the groove, a part of the circlip always protrudes from the groove radially outward of the axis of the shaft. Therefore, it is easy for the circlip to restrict movement of the gear relative to the shaft in the axial direction of the shaft.

[0014] In the above-mentioned transmission, The depth of the groove is preferably 60% or less of the diameter of the cross section of the circlip.

[0015] Therefore, when the circlip is fitted into the groove, the portion of the circlip that protrudes from the groove is sufficiently large, making it easy for the circlip to restrict movement of the gear relative to the shaft in the axial direction of the shaft.

[0016] In the above-mentioned transmission, It is preferable that the groove has a semicircular shape in a cross section along the axis of the shaft portion.

[0017] Therefore, the groove portion comes into proper contact with the circlip. It is easy to increase the contact area between the circlip and the groove portion. Therefore, it is more difficult for the circlip to deform the groove portion. Therefore, it is more easy to prevent the circlip from coming off the groove portion.

[0018] In the above-mentioned transmission, It is preferable that the groove portion has an arc portion and a straight portion, and that the arc portion and the straight portion are continuous with each other.

[0019] Therefore, it is easy to form the grooves.

[0020] In the above-mentioned transmission, The shaft portion and the gear are preferably coupled together by press fitting. In other words, in the above-mentioned transmission, The shaft portion is preferably press-fitted into the through hole.

[0021] Therefore, when a relatively large force is applied to the gear, the gear may move relative to the shaft in the axial direction of the shaft, and may also move relative to the shaft around the axis of the shaft. When the gear moves relative to the shaft in the axial direction of the shaft, and when the gear moves relative to the shaft around the axis of the shaft, the gear simultaneously applies a thrust force and a rotational force to the circlip. The thrust force is a force in the axial direction of the shaft. The rotational force is a force about the axis of the shaft. As described above, the circlip has a circular cross section. Therefore, even when a thrust force and a rotational force act simultaneously on the circlip, the circlip is unlikely to deform the groove. Therefore, even when a thrust force and a rotational force act simultaneously on the circlip, it is easy to prevent the circlip from coming off the groove. Rather, when a thrust force and a rotational force act simultaneously on the circlip, the effect of this transmission in preventing the circlip from coming off is remarkable.

[0022] In the above-mentioned transmission, The gear is preferably a helical gear.

[0023] For this reason, the thrust force that the gear applies to the circlip can be relatively large. As described above, the circlip has a circular cross section. Therefore, even when a relatively large thrust force acts on the circlip, the circlip is unlikely to deform the groove. Therefore, even when a relatively large thrust force acts on the circlip, it is easy to prevent the circlip from coming off the groove. Rather, when a relatively large thrust force acts on the circlip, the effect of this transmission in preventing the circlip from coming off is remarkable.

[0024] In the above-mentioned transmission, It is preferable that the through hole has a first end portion facing the circlip, and the gear has a chamfered portion that widens the diameter of the first end portion toward the circlip.

[0025] Therefore, the chamfered portion shifts the contact position between the gear and the circlip radially outward from the axis of the shaft portion, making it easier to prevent the circlip from slipping out of the groove when the gear comes into contact with the circlip.

[0026] In the above-mentioned transmission, It is preferable that the chamfered portion has an outer peripheral edge, the circlip has an outer peripheral edge, and when the circlip is fitted into the groove, the outer peripheral edge of the chamfered portion is located inward from the outer peripheral edge of the circlip.

[0027] [Function and Effect] Therefore, the chamfered portion is small, which makes it easy to prevent the gear from becoming too large.

[0028] In the above-mentioned transmission, In a cross section of the shaft taken along the axis, the angle between the chamfered portion and the shaft is preferably 45 degrees or less.

[0029] For this reason, when the gear comes into contact with the circlip, the force that the gear applies to the circlip increases relatively slowly. Therefore, when the gear comes into contact with the circlip, the force that the circlip applies to the groove increases relatively slowly. Therefore, even when the gear comes into contact with the circlip, it is more difficult for the circlip to deform the groove. Therefore, it is more easy to prevent the circlip from coming off the groove.

[0030] In the above-mentioned transmission, The chamfered portion preferably has an inner peripheral edge, and the inner peripheral edge preferably contacts the shaft portion.

[0031] Therefore, the contact area between the gear and the shaft in the axial direction of the shaft is not reduced due to the chamfered portion, and it is easy to prevent a reduction in the contact area between the gear and the shaft.

[0032] In the above-mentioned transmission, The chamfered portion preferably has a first length in the axial direction, and the first length is preferably smaller than the diameter of the cross section of the circlip.

[0033] Therefore, it is easy to make the chamfered portion small, and therefore it is easy to prevent the gear from becoming too large.

[0034] In the above-mentioned transmission, The circlip preferably comes into direct contact with the groove.

[0035] Therefore, it is easy to make the depth of the groove shallower, and therefore it is easy to maintain the strength of the shaft.

[0036] The present invention is a saddle-ride type vehicle equipped with the above-described transmission.

[0037] A straddle-type vehicle is equipped with a transmission. The transmission is equipped with a circlip. As described above, it is easy to prevent the circlip from coming off. [Effects of the Invention]

[0038] According to the present invention, it is easy to prevent the circlip from coming off. [Brief explanation of the drawings]

[0039] [Figure 1] 1 is a left side view of a saddle-ride type vehicle according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. [Figure 4] Figure 4(a) is a cross-sectional view of a portion of the gear, and Figure 4(b) is a side view of a portion of the gear. [Figure 5] FIG. 4 is a cross-sectional view of a portion of the shaft and gear. [Figure 6] Figure 6(a) is a plan view of the circlip, Figure 6(b) is a front view of the circlip, and Figure 6(c) is a cross-sectional view of the circlip taken along line cc in Figure 6(a). [Figure 7] FIG. 4 is a cross-sectional view of a portion of the shaft, gear, and circlip. [Figure 8] FIG. 4 is a cross-sectional view of a portion of the shaft, gear, and circlip. [Figure 9] FIG. 10 is a cross-sectional view of a portion of a shaft portion and a gear according to a modified embodiment. [Figure 10] FIG. 10 is a cross-sectional view of a portion of a shaft portion and a gear according to a modified embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0040] A saddle-ride type vehicle according to the present invention will now be described with reference to the drawings.

[0041] 1. Schematic configuration of saddle-type vehicle 1 1 is a left side view of a saddle-ride type vehicle 1 according to an embodiment. The schematic configuration of the saddle-ride type vehicle 1 will be described.

[0042] FIG. 1 shows the front-rear direction X, width direction Y, and up-down direction Z of a saddle riding type vehicle 1. The front-rear direction X, width direction Y, and up-down direction Z are defined relative to a driver (also called a rider) riding on the saddle riding type vehicle 1. The front-rear direction X, width direction Y, and up-down direction Z are perpendicular to each other. The front-rear direction X and width direction Y are horizontal. The up-down direction Z is vertical.

[0043] The terms "front," "rear," "up," "down," "right," and "left" refer to the directions of a driver riding in the saddle-riding vehicle 1, respectively. Unless otherwise specified, "front" and "rear" in this specification include not only directions parallel to the longitudinal direction X but also directions close to the longitudinal direction X. A direction close to the longitudinal direction X is, for example, a direction forming an angle of 45 degrees or less with the longitudinal direction X. Similarly, unless otherwise specified, "right" and "left" include not only directions parallel to the width direction Y but also directions close to the width direction Y. Unless otherwise specified, "up" and "down" include not only directions parallel to the vertical direction Z but also directions close to the vertical direction Z. In each drawing, FRONT, REAR, UP, DOWN, RIGHT, and LEFT are indicated as appropriate for reference.

[0044] The saddle-type vehicle 1 includes a handlebar 2, a front fork 3, and a front wheel 4. The front fork 3 is connected to the handlebar 2. The front fork 3 extends downward and forward from the handlebar 2. The front wheel 4 is supported at a lower part of the front fork 3. The front wheel 4 is rotatable relative to the front fork 3.

[0045] The saddle-type vehicle 1 includes a power unit 10 and a rear wheel 5. The rear wheel 5 is supported by the power unit 10. The rear wheel 5 is supported at a rear portion of the power unit 10. The power unit 10 drives and rotates the rear wheel 5. The power unit 10 is supported by a body frame (not shown). The power unit 10 swings relative to the body frame. The power unit 10 extends rearward from the body frame.

[0046] 2 is a cross-sectional view of the power unit 10 taken along line II-II in FIG. 1. The power unit 10 includes an engine 20 and a transmission 30. The engine 20 generates power. The transmission 30 transmits the power from the engine 20 to rear wheels 5. The rear wheels 5 rotate due to the power transmitted to them.

[0047] The engine 20 includes a crankcase 21, a crankshaft 22, and a cylinder unit 23. The crankcase 21 houses the crankshaft 22. The cylinder unit 23 is provided in front of the crankcase 21. The cylinder unit 23 is connected to the crankcase 21. The cylinder unit 23 extends forward from the crankcase 21.

[0048] The cylinder unit 23 has a cylinder body 23a, a cylinder head 23b, and a cylinder hole 23c. The cylinder head 23b is connected to the cylinder body 23a. The cylinder body 23a is connected to the crankcase 21. The cylinder hole 23c is formed in the cylinder body 23a. The cylinder hole 23c is a space.

[0049] The engine 20 includes a piston 24 and a connecting rod 25. The piston 24 is housed in a cylinder bore 23c. The piston 24 slides within the cylinder bore 23c. The piston 24 is connected to the connecting rod 25. The connecting rod 25 is connected to a crankshaft 22. The piston 24 is connected to the crankshaft 22 via the connecting rod 25. Power from the engine 20 is output through the crankshaft 22.

[0050] The transmission 30 includes a primary shaft 31, a primary pulley 32, a secondary shaft 33, a secondary pulley 34, and a V-belt 35. The primary shaft 31 is connected to the crankshaft 22. The primary shaft 31 is integral with the crankshaft 22. The primary shaft 31 supports the primary pulley 32. The secondary shaft 33 is disposed parallel to the primary shaft 31. The secondary shaft 33 supports the secondary pulley 34. The V-belt 35 is wound around the primary pulley 32 and the secondary pulley 34.

[0051] The primary pulley 32 has a primary fixed sheave 32a and a primary movable sheave 32b. The primary fixed sheave 32a is fixed to the primary shaft 31. The primary fixed sheave 32a does not move relative to the primary shaft 31. The primary fixed sheave 32a rotates together with the primary shaft 31.

[0052] The primary moving sheave 32b is disposed opposite the primary fixed sheave 32a. The primary moving sheave 32b is supported by the primary shaft 31 so as to be movable relative to the primary shaft 31. The primary moving sheave 32b is movable in the axial direction of the primary shaft 31. The primary moving sheave 32b rotates together with the primary shaft 31.

[0053] The distance between the primary fixed sheave 32a and the primary movable sheave 32b changes as the primary movable sheave 32b moves in the axial direction relative to the primary shaft 31. This changes the winding diameter of the V-belt 35 around the primary pulley 32.

[0054] The secondary pulley 34 has a secondary fixed sheave 34a and a secondary movable sheave 34b. The secondary fixed sheave 34a is fixed to the secondary shaft 33. The secondary fixed sheave 34a does not move relative to the secondary shaft 33. The secondary fixed sheave 34a rotates together with the secondary shaft 33.

[0055] The secondary moving sheave 34b is disposed opposite the secondary fixed sheave 34a. The secondary moving sheave 34b is supported by the secondary shaft 33 so as to be movable relative to the secondary shaft 33. The secondary moving sheave 34b is movable in the axial direction of the secondary shaft 33. The secondary moving sheave 34b rotates together with the secondary shaft 33.

[0056] The distance between the secondary fixed sheave 34a and the secondary movable sheave 34b changes as the secondary movable sheave 34b moves in the axial direction relative to the secondary shaft 33. This changes the winding diameter of the V-belt 35 around the secondary pulley 34.

[0057] The secondary pulley 34 includes a spring 34c that biases the secondary movable sheave 34b toward the secondary fixed sheave 34a.

[0058] The transmission 30 changes the gear ratio by changing the winding diameter of the V-belt 35 around the primary pulley 32 and the secondary pulley 34. The gear ratio is the ratio between the rotation speed of the primary shaft 31 and the rotation speed of the secondary shaft 33.

[0059] The transmission 30 includes a reducer 40. The reducer 40 transmits power from the secondary shaft 33 to the rear wheel 5.

[0060] The reducer 40 includes an input shaft 41 and an output shaft 43. The reducer 40 transmits power from the input shaft 41 to the output shaft 43.

[0061] The input shaft 41 is connected to the secondary shaft 33. The input shaft 41 is integral with the secondary shaft 33.

[0062] The output shaft 43 is arranged parallel to the input shaft 41. The reducer 40 rotatably supports the output shaft 43. The output shaft 43 is rotatable around an axis C. The axis C is the central axis of the output shaft 43. The output shaft 43 is connected to the rear wheel 5. The output shaft 43 supports the rear wheel 5. The output shaft 43 is a drive shaft for rotating the rear wheel 5. The rear wheel 5 rotates together with the output shaft 43.

[0063] 3 is a cross-sectional view of the reducer 40. The reducer 40 includes an intermediate shaft 42. The intermediate shaft 42 is disposed between an input shaft 41 and an output shaft 43. The intermediate shaft 42 connects the input shaft 41 and the output shaft 43. Power is transmitted from the input shaft 41 to the output shaft 43 via the intermediate shaft 42.

[0064] The reducer 40 includes a gear 41a and a first gear 44. The gear 41a is integrally formed with the input shaft 41. The first gear 44 is supported by an intermediate shaft 42. Specifically, the first gear 44 has a through hole A. The through hole A is a space. The intermediate shaft 42 is inserted into the through hole A. The first gear 44 meshes with the gear 41a. The input shaft 41 and the intermediate shaft 42 are connected via the gear 41a and the first gear 44.

[0065] The reducer 40 includes a gear 42a and a second gear 45. The gear 42a is formed on the intermediate shaft 42. The second gear 45 is supported on the output shaft 43. Specifically, the second gear 45 has a through hole B. The through hole B is a space. The output shaft 43 is inserted into the through hole B. The second gear 45 meshes with the gear 42a of the intermediate shaft 42. The intermediate shaft 42 and the output shaft 43 are connected via the gear 42a and the second gear 45.

[0066] The second gear 45 has an outer peripheral surface 45a. The outer peripheral surface 45a extends in the circumferential direction of the axis C. The outer peripheral surface 45a contacts the gear 42a. The outer peripheral surface 45a has teeth for meshing with the gear 42a. When power is transmitted between the gear 42a and the second gear 45, a rotational force acts on the second gear 45. The rotational force is a force around the axis C.

[0067] Hereinafter, the direction around the axis C of the output shaft 43 will be referred to as the "first rotation direction" where appropriate.

[0068] For example, gear 42a is a helical gear.

[0069] For example, the second gear 45 is also a helical gear. The teeth of the second gear 45 are formed obliquely with respect to the central axis of the second gear 45. The teeth of the second gear 45 are formed obliquely with respect to the axis C.

[0070] When the second gear 45 is a helical gear, a rotational force and a thrust force act on the second gear 45 when power is transmitted between the gear 42a and the second gear 45. The thrust force is a force in the direction of the axis C. The thrust force is also called a thrust load. The thrust force is also called an axial load.

[0071] The direction parallel to the axis C is referred to as the "thrust direction" as appropriate.

[0072] For example, the output shaft 43 and the second gear 45 are coupled by press-fitting. The output shaft 43 is press-fitted into the through-hole B. For example, the press-fitting is a strong press-fitting. For example, the press-fitting is an interference fit.

[0073] The second gear 45 is fixed to the output shaft 43 by press-fitting. When the second gear 45 is fixed to the output shaft 43, the second gear 45 rotates together with the output shaft 43. When the second gear 45 is fixed to the output shaft 43, the second gear 45 rotates integrally with the output shaft 43. When the second gear 45 is fixed to the output shaft 43, the second gear 45 is immovable relative to the output shaft 43. When the second gear 45 is fixed to the output shaft 43, the second gear 45 is immovable relative to the output shaft 43 in the first rotational direction. When the second gear 45 is fixed to the output shaft 43, the second gear 45 is immovable in the thrust direction relative to the output shaft 43.

[0074] However, even when the second gear 45 is fixed to the output shaft 43, if an extremely large impact acts on the second gear 45, the second gear 45 may slip relative to the output shaft 43. When the output shaft 43 and the second gear 45 are coupled by press fitting, the second gear 45 may slip in the first rotation direction relative to the output shaft 43. When the output shaft 43 and the second gear 45 are coupled by press fitting, the second gear 45 may slip in the thrust direction relative to the output shaft 43. When the output shaft 43 and the second gear 45 are coupled by press fitting, the second gear 45 may slip in the first rotation direction and the thrust direction relative to the output shaft 43 at the same time.

[0075] The reducer 40 includes a circlip 46. The circlip 46 is attached to the output shaft 43. The circlip 46 restricts the second gear 45 from moving relative to the output shaft 43 in the thrust direction.

[0076] The output shaft 43 has a groove 43a in which a circlip 46 is fitted.

[0077] The circlip 46 and the second gear 45 are aligned along the axis C. The circlip 46 is disposed to the left of the second gear 45, for example.

[0078] The circlip 46 is separated from the second gear 45. The circlip 46 is not in contact with the second gear 45. However, if the second gear 45 were to move in the thrust direction relative to the output shaft 43, the second gear 45 would come into contact with the circlip 46. When the second gear 45 comes into contact with the circlip 46, the circlip 46 prevents the second gear 45 from moving further in the thrust direction relative to the output shaft 43.

[0079] The second gear 45 has a side surface 45b. The side surface 45b extends in a radial direction of the axis C. The side surface 45b is, for example, perpendicular to the axis C.

[0080] For example, the circlip 46 faces the side surface 45b. If the second gear 45 moves in the thrust direction relative to the output shaft 43, the circlip 46 comes into contact with the side surface 45b.

[0081] The output shaft 43 corresponds to the shaft portion of the present invention. The second gear 45 corresponds to the gear of the present invention.

[0082] 2. 2nd gear 45 Fig. 4(a) is a cross-sectional view of a portion of the second gear 45. Fig. 4(b) is a side view of a portion of the second gear 45. When viewed from the axis C, the second gear 45 has a substantially annular shape.

[0083] The through hole B extends along the axis C. The through hole B has a first end B1. The first end B1 is located near the side surface 45b. The first end B1 is a part of the through hole B.

[0084] The second gear 45 has an inner peripheral surface 45c. The inner peripheral surface 45c extends in the circumferential direction of the axis C. The inner peripheral surface 45c defines the through hole B. The inner peripheral surface 45c is in contact with the through hole B.

[0085] The inner circumferential surface 45c includes a joint 45d. In a cross section taken along the axis C, the joint 45d extends linearly. In a cross section parallel to the axis C, the joint 45d is parallel to the axis C.

[0086] The joint portion 45d has an inner diameter D1 that is constant along the axis C.

[0087] The inner circumferential surface 45c further includes a chamfered portion 45e. In a cross section parallel to the axis C, the chamfered portion 45e is inclined with respect to the axis C. The chamfered portion 45e is tapered. The chamfered portion 45e is an inclined surface. For example, in a cross section parallel to the axis C, the chamfered portion 45e extends linearly. Alternatively, in a cross section parallel to the axis C, the chamfered portion 45e may be curved.

[0088] The chamfered portion 45e defines a first end B1 of the through-hole B. The chamfered portion 45e extends from the joint portion 45d to the side surface 45b.

[0089] The chamfered portion 45e includes an inner peripheral edge 45f. The inner peripheral edge 45f is located at the boundary between the chamfered portion 45e and the joint portion 45d. The inner peripheral edge 45f has an inner diameter equal to the inner diameter D1.

[0090] The chamfered portion 45e includes an outer peripheral edge 45g. The outer peripheral edge 45g is located at the boundary between the chamfered portion 45e and the side surface 45b. The outer peripheral edge 45g has an inner diameter D2. The inner diameter D2 is greater than the inner diameter D1.

[0091] When viewed from the axis C, the outer peripheral edge 45g is a circle centered on the axis C. When viewed from the axis C, the inner peripheral edge 45f is a circle centered on the axis C. The inner peripheral edge 45f is smaller than the outer peripheral edge 45g. The inner peripheral edge 45f is located inward of the outer peripheral edge 45g.

[0092] 5 is a cross-sectional view of a portion of the output shaft 43 and the second gear 45. The joint portion 45d contacts the output shaft 43. The joint portion 45d is joined to the output shaft 43.

[0093] The chamfered portion 45e does not contact the output shaft 43. The chamfered portion 45e is spaced apart from the output shaft 43.

[0094] The inner peripheral edge 45f contacts the output shaft 43.

[0095] The outer peripheral edge 45g does not contact the output shaft 43. The outer peripheral edge 45g is spaced apart from the output shaft 43.

[0096] The chamfered portion 45e has an inclination angle θ. The inclination angle θ is the angle between the chamfered portion 45e and the output shaft 43 in a cross section along the axis C. For example, the inclination angle θ is 45 degrees or less.

[0097] The chamfered portion 45e has a first length D3 and a second length D4. The first length D3 is the length of the chamfered portion 45e along the axis C. The second length D4 is the length of the chamfered portion 45e along the radial direction of the axis C. The first length D3 is greater than the second length D4.

[0098] 3. Groove The groove 43a is formed on the outer circumferential surface of the output shaft 43. The groove 43a extends around the axis C of the output shaft 43.

[0099] The groove 43a is recessed from the outer peripheral surface of the output shaft 43 inward in the radial direction of the axis C. The groove 43a is recessed from the outer peripheral surface of the output shaft 43 inward in the radial direction of the axis C.

[0100] FIG. 5 shows the boundary K. The boundary K is an imaginary curved surface that indicates the gap between the inside and outside of the groove portion 43a. The boundary K is located on an extension of the outer peripheral surface of the output shaft 43. The groove portion 43a is recessed radially inward from the boundary K with respect to the axis C. The groove portion 43a is recessed radially inward from the boundary K with respect to the axis C.

[0101] The groove 43a has a depth D5, which is the length of the groove 43a in the radial direction of the axis C.

[0102] The depth D5 is greater than the second length D4.

[0103] The depth D5 is less than the first length D3.

[0104] For example, in a cross section along the axis C, the groove portion 43a has a semicircular shape.

[0105] Specifically, the groove portion 43a includes an arc portion 43b. The arc portion 43b has an arc shape in a cross section along the axis C. The arc portion 43b is semicircular.

[0106] The groove 43a does not face the joining portion 45d, and the groove 43a does not face the inner peripheral edge 45f.

[0107] 4. Circlip 46 The circlip 46 will now be described. Figure 6 is a diagram showing the circlip 46. Figure 6(a) is a plan view of the circlip 46. Figure 6(b) is a front view of the circlip 46. Figure 6(c) is a cross-sectional view taken along line cc in Figure 6(a).

[0108] The circlip 46 is a type of retaining ring.

[0109] The circlip 46 is formed in an annular shape and has a notched portion 46a formed by cutting out a part of the annular shape.

[0110] Specifically, the circlip 46 includes a ring 47. The ring 47 forms a notch 46a. The ring 47 has an open end. The ring 47 has a first end 47a and a second end 47b. The second end 47b of the ring 47 is spaced apart from the first end 47a of the ring 47.

[0111] The circlip 46 has a circular cross section 46b, in other words, the ring 47 has a circular cross section.

[0112] The circlip 46 has elasticity.

[0113] The ring 47 is made of metal. The ring 47 is made of a round wire. The ring 47 is obtained by shaping the round wire.

[0114] The ring 47 is flexible. The ring 47 is semi-flexible. The ring 47 is elastic.

[0115] The circlip 46 has an inner diameter D6.

[0116] The circlip 46 has an outer peripheral edge 46c.

[0117] 7 is a cross-sectional view of a portion of the output shaft 43, the second gear 45, and the circlip 46. The circlip 46 is fitted into the groove portion 43a.

[0118] When the circlip 46 is fitted into the groove portion 43a, the circlip 46 is in direct contact with the groove portion 43a.

[0119] The inner diameter D6 of the circlip 46 in an unloaded state is slightly smaller than the diameter of the groove 43a of the output shaft 43. Therefore, when the circlip 46 is attached to the groove 43a, the inner diameter D6 expands slightly. The circlip 46 exerts an elastic force to reduce the inner diameter D6. Therefore, the circlip 46 pushes the groove 43a radially inward of the axis C. When the circlip 46 is attached to the groove 43a, the elastic restoring force of the circlip 46 causes the circlip 46 to push the groove 43a.

[0120] When the circlip 46 is fitted in the groove portion 43a, more than half of the circlip 46 is housed in the groove portion 43a. When the circlip 46 is fitted in the groove portion 43a, another part of the circlip 46 is located outside the groove portion 43a. When the circlip 46 is fitted in the groove portion 43a, another part of the circlip 46 protrudes from the groove portion 43a.

[0121] The cross section 46b of the circlip 46 has a diameter D7. The depth D5 of the groove 43a is 50% or more of the diameter D7.

[0122] The depth D5 is less than the diameter D7.

[0123] For example, the depth D5 is 60% or less of the diameter D7.

[0124] The cross section 46b of the circlip 46 has a center O.

[0125] For example, when the circlip 46 is fitted in the groove portion 43a, the center O is located on the boundary K. In other words, when the circlip 46 is fitted in the groove portion 43a, the center O is located at the same position as the outer peripheral surface of the output shaft 43 in the radial direction of the axis C.

[0126] Alternatively, when the circlip 46 is fitted in the groove 43 a, the center O is located inside the groove 43 a. In other words, when the circlip 46 is fitted in the groove 43 a, the center O is located inward of the boundary K in the radial direction of the axis C.

[0127] The circlip 46 is separated from the second gear 45. The circlip 46 is not in contact with the second gear 45.

[0128] The circlip 46 and the side surface 45b are spaced apart in the direction of the axis C. For example, the entire circlip 46 may be disposed to the left of the side surface 45b. Alternatively, the entire circlip 46 may be disposed to the right of the side surface 45b.

[0129] The circlip 46 faces the side surface 45b.

[0130] The circlip 46 faces the chamfered portion 45e.

[0131] The circlip 46 faces the first end B1 of the through hole B.

[0132] The inner diameter of the chamfered portion 45e expands toward the circlip 46.

[0133] The chamfered portion 45e increases the diameter of the first end B1 toward the circlip .

[0134] The outer diameter of the circlip 46 is larger than the diameter of the inner peripheral edge 45f of the chamfered portion 45e.

[0135] When the circlip 46 is fitted in the groove portion 43a, the outer peripheral edge 46c of the circlip 46 is located outward in the radial direction of the axis C from the inner peripheral edge 45f of the chamfered portion 45e. In other words, when the circlip 46 is fitted in the groove portion 43a, the inner peripheral edge 45f is located inward in the radial direction of the axis C from the outer peripheral edge 46c.

[0136] The outer diameter of the circlip 46 is larger than the diameter of the outer peripheral edge 45g of the chamfered portion 45e.

[0137] When the circlip 46 is fitted in the groove portion 43a, the outer peripheral edge 46c of the circlip 46 is located outward in the radial direction of the axis C from the outer peripheral edge 45g of the chamfered portion 45e. In other words, when the circlip 46 is fitted in the groove portion 43a, the outer peripheral edge 45g is located inward in the radial direction of the axis C from the outer peripheral edge 46c.

[0138] The first length D3 of the chamfered portion 45e is smaller than the diameter D7 of the cross section 46b.

[0139] The second length D4 of the chamfered portion 45e is smaller than the diameter D7.

[0140] The second length D4 is smaller than half the diameter D7, which corresponds to the radius of the cross section 46b.

[0141] The sum of the second length D4 and the depth D5 is smaller than the diameter D7.

[0142] 8 is a cross-sectional view of a portion of the output shaft 43, the second gear 45, and the circlip 46. In FIG.

[0143] The second gear 45 may slip relative to the output shaft 43. The second gear 45 may move relative to the output shaft 43. The movement of the second gear 45 may be caused, for example, by an excessively large force or an excessively large torque being input to the second gear 45. For example, the gear 42a may apply an excessively large force or an excessively large torque to the second gear 45. For example, the output shaft 43 may apply an excessively large force or an excessively large torque to the second gear 45.

[0144] When the second gear 45 moves in the thrust direction relative to the output shaft 43, the second gear 45 may come into contact with the circlip 46. When the second gear 45 comes into contact with the circlip 46, the second gear 45 applies a thrust force to the circlip 46.

[0145] As described above, when the output shaft 43 and the second gear 45 are coupled by press fitting, the second gear 45 may simultaneously slip in the first rotation direction and the thrust direction relative to the output shaft 43. Therefore, when the second gear 45 comes into contact with the circlip 46, the second gear 45 may simultaneously apply a thrust force and a rotation force to the circlip 46.

[0146] When the second gear 45 abuts against the circlip 46 , the outer peripheral edge 45 g comes into contact with the circlip 46 .

[0147] 8 shows the contact position E between the second gear 45 and the circlip 46. The contact position E is shifted radially outwardly about the axis C. The contact position E is shifted radially outwardly about the axis C by the second length D4.

[0148] Specifically, the contact position E is located radially outward from the boundary K in the direction of the axis C. In other words, the contact position E is located radially outward from the outer circumferential surface of the output shaft 43 in the direction of the axis C. For example, the contact position E is located radially outward from the center O in the direction of the axis C.

[0149] 5. Effects of the embodiment The transmission 30 includes an output shaft 43, a second gear 45, and a circlip 46. The output shaft 43 has a groove 43a. The second gear 45 has a through hole B for inserting the output shaft 43. The second gear 45 is supported on the output shaft 43. The circlip 46 is fitted into the groove 43a. The circlip 46 restricts movement of the second gear 45 relative to the output shaft 43 in the direction of the axis C of the output shaft 43.

[0150] The circlip 46 has a cross section 46b. The cross section 46b of the circlip 46 is circular. Therefore, the circlip 46 does not easily deform the groove portion 43a. Even when the second gear 45 comes into contact with the circlip 46, the circlip 46 does not easily deform the groove portion 43a. Even when a thrust force acts on the circlip 46, the circlip 46 does not easily deform the groove portion 43a. Therefore, the circlip 46 does not easily come off the groove portion 43a. In other words, it is easy to prevent the circlip 46 from coming off the groove portion 43a. Therefore, it is easy for the circlip 46 to restrict the movement of the second gear 45 described above. It is easy for the circlip 46 to restrict the movement of the second gear 45 described above with a simple structure.

[0151] In summary, it is easy to prevent the circlip 46 from coming off in the transmission 30. Therefore, in the transmission 30, it is easy to restrict the second gear 45 from moving relative to the output shaft 43 in the direction of the axis C of the output shaft 43.

[0152] As described above, the circlip 46 has a circular cross section, which makes it easy for the circlip 46 to restrict the above-described movement of the second gear 45 with an inexpensive and highly reliable structure.

[0153] For example, the circlip 46 has a circular cross section 46b. Therefore, the circlip 46 can be molded inexpensively. Therefore, it is easy to reduce the cost of the structure for restricting the movement of the second gear 45 described above.

[0154] For example, the circlip 46 has a circular cross section 46b. This allows the depth D5 of the groove 43a of the output shaft 43 to be shallow. This prevents excessive reduction in the strength of the output shaft 43. Therefore, the structure for restricting the movement of the second gear 45 has high reliability.

[0155] When the circlip 46 is fitted into the groove portion 43a, more than half of the circlip 46 is housed in the groove portion 43a, which makes it even easier to prevent the circlip 46 from coming out of the groove portion 43a.

[0156] Specifically, when the second gear 45 abuts against the circlip 46, the contact position E between the second gear 45 and the circlip 46 is shifted outward in the radial direction of the axis C. For example, the contact position E is located outward in the radial direction of the axis C from the center O. Therefore, when the second gear 45 abuts against the circlip 46, the circlip 46 is likely to be pressed inward in the radial direction of the axis C by the second gear 45. Therefore, when the second gear 45 abuts against the circlip 46, the circlip 46 is likely to be pressed toward the groove portion 43a. Therefore, it is even easier to prevent the circlip 46 from coming off the groove portion 43a.

[0157] The depth D5 of the groove 43a is 50% or more of the diameter D7 of the cross section 46b of the circlip 46, and is less than the diameter D7 of the cross section 46b of the circlip 46.

[0158] The depth D5 is 50% or more of the diameter D7, so that it is easy to accommodate more than half of the circlip 46 in the groove portion 43a.

[0159] The depth D5 is less than the diameter D7. For this reason, it is impossible for the groove 43a to accommodate the entire circlip 46. Therefore, when the circlip 46 is fitted in the groove 43a, a portion of the circlip 46 always protrudes from the groove 43a. When the circlip 46 is fitted in the groove 43a, a portion of the circlip 46 always protrudes outward from the groove 43a in the radial direction of the axis C. Therefore, when the circlip 46 is fitted in the groove 43a, the circlip 46 always restricts the second gear 45 from moving relative to the output shaft 43 in the direction of the axis C.

[0160] The depth D5 is 60% or less of the diameter D7. Therefore, when the circlip 46 is fitted in the groove 43a, the portion of the circlip 46 that protrudes from the groove 43a is sufficiently large. Therefore, it is easy for the circlip 46 to restrict movement of the second gear 45 in the direction of the axis C relative to the output shaft 43.

[0161] As described above, the depth D5 is 60% or less of the diameter D7. Therefore, the depth D5 of the groove 43a is relatively shallow. Therefore, the strength of the output shaft 43 is not excessively reduced. The reduction in the strength of the output shaft 43 due to the formation of the groove 43a in the output shaft 43 can be suppressed.

[0162] In a cross section along the axis C, the groove portion 43a is semicircular. Therefore, the groove portion 43a comes into appropriate contact with the circlip 46. It is easy to increase the contact area between the circlip 46 and the groove portion 43a. Therefore, it is more difficult for the circlip 46 to deform the groove portion 43a. Therefore, it is more easy to prevent the circlip 46 from coming off the groove portion 43a.

[0163] The output shaft 43 and the second gear 45 are coupled by press-fitting. In other words, the output shaft 43 is press-fitted into the through-hole B. Therefore, when a relatively large force is applied to the second gear 45, the second gear 45 may move relative to the output shaft 43 in the direction of the axis C and may also move relative to the output shaft 43 around the axis of the output shaft 43. When the second gear 45 moves relative to the output shaft 43 in the direction of the axis C and moves relative to the output shaft 43 around the axis C, the second gear 45 simultaneously applies a thrust force and a rotational force to the circlip 46. As described above, the circlip 46 has a circular cross section 46b. Therefore, even when a thrust force and a rotational force simultaneously act on the circlip 46, the circlip 46 is unlikely to deform the groove portion 43a. Therefore, it is easy to prevent the circlip 46 from coming off the groove 43a even when a thrust force and a rotational force act simultaneously on the circlip 46. In fact, when a thrust force and a rotational force act simultaneously on the circlip 46, the effect of the present transmission in preventing the circlip 46 from coming off is remarkable.

[0164] When a relatively large force is applied to the second gear 45, the press-fit connection between the output shaft 43 and the second gear 45 may not be maintained. When the press-fit connection between the output shaft 43 and the second gear 45 may not be maintained, the second gear 45 moves relative to the output shaft 43. For example, when the press-fit connection between the output shaft 43 and the second gear 45 may not be maintained, the second gear 45 moves relative to the output shaft 43 in the thrust direction. For example, when the press-fit connection between the output shaft 43 and the second gear 45 may not be maintained, the second gear 45 may move relative to the output shaft 43 in the first rotation direction. For example, when the press-fit connection between the output shaft 43 and the second gear 45 may not be maintained, the second gear 45 may move relative to the output shaft 43 in both the thrust direction and the first rotation direction at the same time. Therefore, the second gear 45 may apply a thrust force and a rotational force to the circlip 46 at the same time. As described above, the circlip 46 has a circular cross section 46b. Therefore, even when a thrust force and a rotational force act simultaneously on the circlip 46, in the present transmission 30, the circlip 46 is unlikely to deform the groove 43a. Therefore, even when a thrust force and a rotational force act simultaneously on the circlip 46, it is easy to prevent the circlip 46 from coming off the groove 43a. In fact, when a thrust force and a rotational force act simultaneously on the circlip 46, the effect of the present transmission 30 in preventing the circlip 46 from coming off is remarkable.

[0165] The second gear 45 is a helical gear. Therefore, the thrust force that the second gear 45 applies to the circlip 46 can be relatively large. As described above, the circlip 46 has a circular cross section 46b. Therefore, even when a relatively large thrust force acts on the circlip 46, the circlip 46 is unlikely to deform the groove 43a. Therefore, even when a relatively large thrust force acts on the circlip 46, it is easy to prevent the circlip 46 from coming off the groove 43a. In fact, when a relatively large thrust force acts on the circlip 46, the effect of the transmission 30 in preventing the circlip 46 from coming off is remarkable.

[0166] The through hole B has a first end B1. The first end B1 faces the circlip 46. The second gear 45 has a chamfered portion 45e. The chamfered portion 45e expands the inner diameter of the first end B1 toward the circlip 46. Therefore, the chamfered portion 45e shifts the contact position E radially outwardly about the axis C. Therefore, when the second gear 45 comes into contact with the circlip 46, it is even easier to prevent the circlip 46 from slipping out of the groove.

[0167] Specifically, when the second gear 45 abuts against the circlip 46, the contact position E between the second gear 45 and the circlip 46 is shifted outward in the radial direction of the axis C. For example, the contact position E is located outward in the radial direction of the axis C from the center O. Therefore, when the second gear 45 abuts against the circlip 46, the circlip 46 is likely to be pressed inward in the radial direction of the axis C by the second gear 45. Therefore, when the second gear 45 abuts against the circlip 46, the circlip 46 is likely to be pressed toward the groove portion 43a. Therefore, when the second gear 45 abuts against the circlip 46, it is even easier to prevent the circlip 46 from coming out of the groove portion.

[0168] As described above, the second gear 45 has the chamfered portion 45e. This makes it easier to press-fit the output shaft 43 into the through-hole B of the second gear 45. It is easy to fit the output shaft 43 and the second gear 45 together. It is also easy to align the output shaft 43 and the second gear 45 when connecting them.

[0169] Incidentally, the gear may originally have a chamfered portion in order to couple with the shaft portion. When the gear originally has a chamfered portion, the gear can be used as the second gear 45 without changing the shape of the gear. For example, the gear can be used as the second gear 45 without changing the design of the gear or machining the gear.

[0170] The chamfered portion 45e has an outer peripheral edge 45g. The circlip 46 has an outer peripheral edge 46c. When the circlip 46 is fitted in the groove portion 43a, the outer peripheral edge 45g is located inward of the outer peripheral edge 46c. Therefore, the chamfered portion 45e is small, and it is easy to prevent the second gear 45 from becoming large.

[0171] In a cross section along the axis C, the angle θ between the chamfered portion 45e and the output shaft 43 is 45 degrees or less. For this reason, when the second gear 45 comes into contact with the circlip 46, the force that the second gear 45 applies to the circlip 46 increases relatively gradually. Therefore, when the second gear 45 comes into contact with the circlip 46, the force that the circlip 46 applies to the groove portion 43a increases relatively gradually. Therefore, even when the second gear 45 comes into contact with the circlip 46, it is more difficult for the circlip 46 to deform the groove portion 43a. Therefore, it is more easy to prevent the circlip 46 from coming off the groove portion 43a.

[0172] The chamfered portion 45e has an inner peripheral edge 45f that contacts the output shaft 43. Therefore, the chamfered portion 45e does not reduce the contact area between the second gear 45 and the output shaft 43 in the direction of the axis C. Therefore, it is easy to prevent a reduction in the contact area between the second gear 45 and the output shaft 43.

[0173] The chamfered portion 45e has a first length D3 in the direction of the axis C. The first length D3 is smaller than the diameter D7 of the cross section 46b of the circlip 46. Therefore, it is easy to reduce the size of the chamfered portion 45e, and therefore it is easy to prevent the second gear 45 from becoming large.

[0174] The circlip 46 is in direct contact with the groove 43a. Therefore, it is easy to make the depth D5 of the groove 43a shallow, and therefore it is easy to maintain the strength of the output shaft 43.

[0175] The saddle-type vehicle 1 is equipped with the above-mentioned transmission 30. The transmission 30 includes the circlip 46. As described above, it is easy to prevent the circlip 46 from coming off.

[0176] 6. Modified Embodiments The present invention is not limited to the above-described embodiment, but can be modified as follows.

[0177] (1) In the above-described embodiment, the groove portion 43a is formed in a semicircular shape in a cross section taken along the axis C. However, the present invention is not limited to such an embodiment. The groove portion 43a may have an arc portion and a linear portion in a cross section taken along the axis C.

[0178] FIG. 9 is an enlarged cross-sectional view of a main part according to a modified embodiment. Detailed description of the same configuration as in the embodiment will be omitted. The groove portion 43a includes an arc portion 43b and a straight portion 43c. The arc portion 43b has an arc shape in a cross section along the axis C. The arc portion 43b is, for example, a quadrant. The straight portion 43c has a straight shape in a cross section along the axis C. The arc portion 43b and the straight portion 43c are continuous. The straight portion 43c is inclined with respect to the axis C. The straight portion 43c is not perpendicular to the axis C. The angle between the straight portion 43c and the axis C is, for example, 30 degrees.

[0179] The arc portion 43b, the straight portion 43c, and the second gear 45 are arranged in this order along the axis C. The straight portion 43c is disposed between the arc portion 43b and the second gear 45 in the direction of the axis C. Therefore, the distance between the arc portion 43b and the second gear 45 in the direction of the axis C is greater than the distance between the straight portion 43c and the second gear 45 in the direction of the axis C.

[0180] The straight portion 43c is provided opposite the chamfered portion 45e. At least a portion of the straight portion 43c is located at the same position as the chamfered portion 45e in the direction of the axis C of the output shaft 43.

[0181] This modified embodiment provides the following advantages.

[0182] The groove 43a includes an arc portion 43b and a linear portion 43c, which are continuous with each other. Therefore, it is easy to form the grooves 43a. For example, the grooves 43a can be formed without changing the angle of the cutting tool blade.

[0183] (2) In the above-described embodiment, the second gear 45 has the chamfered portion 45e. However, the present invention is not limited to such an embodiment. The chamfered portion 45e may be omitted. The second gear 45 does not have to have the chamfered portion 45e.

[0184] 10 is an enlarged cross-sectional view of a main part according to a modified embodiment, and detailed description of the same configuration as in the embodiment will be omitted.

[0185] In a cross section along the axis C, the side surface 45b and the joint portion 45d are in contact with each other.

[0186] In a cross section taken along the axis C, the side surface 45b and the inner peripheral surface 45c intersect at a right angle. In a cross section taken along the axis C, the side surface 45b and the joint portion 45d intersect at a right angle.

[0187] For example, the side surface 45b is perpendicular to the axis C of the output shaft 43. The side surface 45b of the second gear 45 extends radially outward from the joint portion 45d of the second gear 45 with respect to the axis C of the output shaft 43.

[0188] According to this modified embodiment, it is easy to ensure the contact area between the output shaft 43 and the second gear 45. For example, it is easy to increase the length of the joint portion 45d in the direction of the axis C. It is also easy to increase the area of ​​the joint portion 45d.

[0189] (3) In the above-described embodiment, the output shaft 43 and the second gear 45 are coupled by press fitting. However, the present invention is not limited to such an embodiment. The output shaft 43 and the second gear 45 may be coupled by a spline. According to this modified embodiment, the second gear 45 always rotates integrally with the output shaft 43 around the axis C of the output shaft 43. The second gear 45 is always unable to rotate around the axis C of the output shaft 43 relative to the output shaft 43. Even if an extremely large impact acts on the second gear 45, the second gear 45 will not slip relative to the output shaft 43.

[0190] (4) In the above-described embodiment, the output shaft 43 and the second gear 45 are coupled by press-fitting. However, the present invention is not limited to such an embodiment. The second gear 45 may always be supported by the output shaft 43 so as to be rotatable around the axis C of the output shaft 43.

[0191] (5) In the above-described embodiment, the output shaft 43 and the second gear 45 are substantially inseparable from each other. However, the present invention is not limited to such an embodiment. The output shaft 43 and the second gear 45 may be detachable from each other.

[0192] (6) In the above-described embodiment, the reducer 40 rotatably supports the output shaft 43. The output shaft 43 is rotatable about the axis C of the output shaft 43. However, the present invention is not limited to such an embodiment. The reducer 40 may support the output shaft 43 so that it cannot rotate. The output shaft 43 may be unable to rotate about the axis C of the output shaft 43. The output shaft 43 may be fixed to the transmission 30. The output shaft 43 does not have to rotate about the axis C of the output shaft 43.

[0193] (7) In the above-described embodiment, the inclination angle θ is 45 degrees or less. However, the present invention is not limited to such an embodiment. The inclination angle θ may be 30 degrees or less. Furthermore, the inclination angle θ may be 20 degrees or less.

[0194] When the inclination angle θ is small, the force that the circlip 46 applies to the groove portion 43a when the second gear 45 comes into contact with the circlip 46 increases more gradually. Therefore, even when the second gear 45 comes into contact with the circlip 46, it is more difficult for the circlip 46 to deform the groove portion 43a. Therefore, it is easier to prevent the circlip 46 from coming off the groove portion 43a.

[0195] (8) In the above-described embodiment, the outer peripheral edge 45g of the chamfered portion 45e is located radially inward of the axis C relative to the outer peripheral edge 46c of the circlip 46. However, the present invention is not limited to such an embodiment. The outer peripheral edge 45g of the chamfered portion 45e may be located radially outward of the axis C relative to the outer peripheral edge 46c of the circlip 46. In other words, the diameter of the outer peripheral edge 45g of the chamfered portion 45e may be larger than the outer diameter of the circlip 46.

[0196] In this modified embodiment, when the second gear 45 moves in the thrust direction relative to the output shaft 43, the chamfered portion 45e comes into contact with the circlip 46. When the second gear 45 moves in the thrust direction relative to the output shaft 43, the outer peripheral edge 45g of the chamfered portion 45e does not come into contact with the circlip 46. In this modified embodiment as well, the chamfered portion 45e shifts the contact position E outward in the radial direction of the axis C. Therefore, it is even easier to prevent the circlip 46 from coming out of the groove portion 43a.

[0197] (9) In the above-described embodiment, the first length D3 of the chamfered portion 45e is smaller than the diameter D7 of the cross section 46b of the circlip 46. However, the present invention is not limited to such an embodiment. For example, the first length D3 may be greater than the diameter D7.

[0198] (10) In the above-described embodiment, the second gear 45 is a helical gear. However, the second gear 45 is not limited to a helical gear. For example, the second gear 45 may be a spur gear.

[0199] (11) The embodiment and each of the modified embodiments described above in (1) to (10) may be further modified as appropriate by replacing or combining each configuration with the configuration of another modified embodiment. [Explanation of symbols]

[0200] 1: Saddle-type vehicle 2: Handle 3: Front fork 4: Front wheel 5: Rear wheel 10: Power unit 20: Engine 21: Crankcase 22: Crankshaft 23: Cylinder unit 23a: Cylinder body 23b: Cylinder head 23c: Cylinder hole 24: Piston 25: Connecting rod 30: Transmission 31: Primary axis 32: Primary pulley 32a: Primary fixed sheave 32b: Primary moving sheave 33: Secondary axis 34: Secondary pulley 34a: Secondary fixed sheave 34b: Secondary moving sheave 34c: Spring 35: V-belt 40:Reducer 41: Input shaft 41a: Gear 42: Intermediate shaft 42a: Gear 43: Output shaft 43a:Groove 43b: Arc section 43c: Straight section 44: 1st gear 45: 2nd gear 45a: Outer surface 45b: Side 45c: Inner surface 45d: Joint 45e: Chamfered part 45f: Inner edge 45g: outer edge 46: Circlip 46a: Notch 46b: Cross section 46c: Outer edge 47: Ring 47a: 1st end 47b: 2nd end A: Through hole B: Through hole B1: First end

Claims

1. a shaft portion having a groove; a gear having a through hole for inserting the shaft portion and supported by the shaft portion; a circlip that is fitted into the groove and restricts movement of the gear relative to the shaft in the axial direction of the shaft; Equipped with The circlip has a circular cross section. Transmission.

2. 2. The transmission according to claim 1, When the circlip is fitted into the groove, more than half of the circlip is accommodated in the groove. Transmission.

3. 2. The transmission according to claim 1, The depth of the groove is 50% or more of the diameter of the cross section of the circlip and is less than the diameter of the cross section of the circlip. Transmission.

4. 4. The transmission according to claim 3, The depth of the groove is 60% or less of the diameter of the cross section of the circlip. Transmission.

5. 2. The transmission according to claim 1, In a cross section taken along the axis of the shaft portion, the groove portion has a semicircular shape. Transmission.

6. 2. The transmission according to claim 1, The groove portion includes an arc portion and a linear portion, The arc portion and the straight portion are continuous. Transmission.

7. 2. The transmission according to claim 1, The shaft portion and the gear are joined by press fitting. Transmission.

8. 2. The transmission according to claim 1, The gear is a helical gear. Transmission.

9. 2. The transmission according to claim 1, The through hole has a first end facing the circlip, The gear has a chamfer that widens the diameter of the first end toward the circlip. Transmission.

10. 10. The transmission according to claim 9, the chamfered portion has an outer periphery; The circlip has an outer circumferential edge, When the circlip is fitted into the groove, the outer circumferential edge of the chamfered portion is located inward from the outer circumferential edge of the circlip. Transmission.

11. 10. The transmission according to claim 9, In a cross section of the shaft portion taken along the axis, the angle between the chamfered portion and the shaft portion is 45 degrees or less. Transmission.

12. 10. The transmission according to claim 9, the chamfered portion has an inner peripheral edge; The inner circumferential edge contacts the shaft portion. Transmission.

13. 10. The transmission according to claim 9, the chamfered portion has a first length in the axial direction; The first length is smaller than the diameter of the cross section of the circlip. Transmission.

14. 2. The transmission according to claim 1, The circlip is in direct contact with the groove. Transmission.

15. A straddle-type vehicle comprising the transmission according to any one of claims 1 to 14.

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