Sheave for continuously variable transmission, continuously variable transmission, saddle-type vehicle, and method for manufacturing sheave for continuously variable transmission

Abstract

A sheave (100) for a continuously variable transmission comprises: a boss member (110) formed from a first metal material; and a sheave member (120) formed from a second metal material different from the first metal material and including a sheave surface (121) and a rear surface (122). The sheave member is attached to an attachment region (AR), which is a part of an outer peripheral surface (110os) of the boss member, by plastic flow joining. The attachment region has a stepped shape including a first region (R1) of relatively small diameter, a second region (R2) of relatively large diameter, and a step surface (SS1) located at the boundary between the first region and the second region. The first region, the step surface, and the second region are arranged in the above order proceeding from the sheave-surface side to the rear-surface side, and the sheave member is in contact with the step surface.

Description

Sheave for continuously variable transmission, continuously variable transmission, straddle-type vehicle, and method for manufacturing sheave for continuously variable transmission

[0001] The present invention relates to a sheave for a continuously variable transmission, a continuously variable transmission, a straddle-type vehicle, and a method for manufacturing a sheave for a continuously variable transmission.

[0002] Belt-type continuously variable transmissions are widely used in scooter-type motorcycles and the like. Belt-type continuously variable transmissions include a drive pulley, a driven pulley, and a belt stretched between them. The drive pulley is composed of a fixed sheave fixed to the engine crankshaft and a movable sheave that is positioned opposite the fixed sheave and is movable in the axial direction of the crankshaft.

[0003] A commonly used method for moving the movable sheave is to use centrifugal force acting on a centrifugal weight (called a "centrifugal type"), but in recent years, a method using an electric actuator (called an "electronically controlled type") has also been proposed. A continuously variable transmission that employs electronic control for moving the movable sheave is disclosed in, for example, Patent Document 1.

[0004] JP 2018-66434 A

[0005] The movable sheave is required to have a wide range of performance characteristics, such as high strength and rigidity and excellent heat dissipation. In order to improve the performance of the movable sheave, the inventors of the present application considered constructing the movable sheave from multiple components made of different metal materials. By adopting such a configuration, it is possible to arrange the desired appropriate materials in different parts of the movable sheave, and it is believed that the performance of the movable sheave can be improved.

[0006] However, various structures and methods can be considered for specific structures for combining components made of different materials and methods for firmly joining them, and it has been found that depending on the structure and method adopted, as will be described later, manufacturing may become complicated, the positional accuracy during joining may be low, or the layout may need to be expanded.

[0007] The embodiments of the present invention have been made in consideration of the above problems, and their purpose is to provide a suitable structure and manufacturing method for constructing a movable sheave for a continuously variable transmission from multiple components formed from different materials.

[0008] This specification discloses a sheave for a continuously variable transmission, a continuously variable transmission, a saddle-ride type vehicle, and a method for manufacturing a sheave for a continuously variable transmission, as described in the following items.

[0009] [Item 1] A sheave for a continuously variable transmission comprising: a boss member formed from a first metal material and having a boss hole; and a sheave member formed from a second metal material different from the first metal material, the sheave member including a sheave surface that receives a belt and a back surface located on the opposite side of the sheave surface, wherein the sheave member is attached to an attachment region that is a part of the outer peripheral surface of the boss member by plastic flow bonding, and the attachment region has a stepped shape including a first region having a relatively small diameter, a second region having a relatively large diameter, and a stepped surface located at the boundary between the first region and the second region, and the first region, the stepped surface, and the second region are arranged in this order from the sheave surface side toward the back surface side, and the sheave member abuts against the stepped surface.

[0010] In the continuously variable transmission sheave according to the embodiment of the present invention, the boss member and the sheave member are formed from different metal materials, so that it is possible to arrange desired and appropriate materials in different portions of the sheave (specifically, the portion having the boss hole and the portion having the sheave surface that receives the belt). The sheave member is attached to an attachment region that is part of the outer peripheral surface of the boss member by plastic flow bonding. Therefore, even if the sheave member and the boss member are formed from different metal materials, they can be joined relatively easily, with high positional accuracy, and in a compact manner (i.e., without enlarging the layout).

[0011] In a continuously variable transmission sheave according to an embodiment of the present invention, the mounting region, which is part of the outer peripheral surface of the boss member, has a stepped shape including a first region having a relatively small diameter, a second region having a relatively large diameter, and a stepped surface located at the boundary between the first and second regions. The first region, the stepped surface, and the second region are arranged in this order from the sheave face side to the back face side, and the sheave member abuts against the stepped surface. This prevents the sheave member from coming loose due to the force applied from the belt during operation of the continuously variable transmission. In other words, the stepped surface functions as a retainer for the sheave member.

[0012] [Item 2] The sheave for a continuously variable transmission according to item 1, wherein the first region of the mounting region of the boss member has a plurality of grooves, and the sheave member has a plurality of ridges that fit into the plurality of grooves.

[0013] In a continuously variable transmission sheave according to an embodiment of the present invention, for example, the first region of the mounting region of the boss member has a plurality of grooves, and the sheave member has a plurality of ridges that fit into these grooves, thereby achieving a mechanical connection. The ridges of the sheave member can be formed when the sheave member abuts against a stepped surface of the boss member and plastically deforms (more specifically, when the metal material of the sheave member plastically flows into the grooves of the boss member) when the sheave member is mounted to the boss member.

[0014] [Item 3] The sheave for a continuously variable transmission according to Item 2, wherein a gap is provided between the bottom of each of the plurality of grooves and the top of the ridge that fits into the groove.

[0015] From the viewpoint of preventing cracking of the sheave member during plastic flow bonding, it is preferable to provide a gap between the bottom of each groove and the top of the ridge that fits into that groove. If plastic flow bonding is performed so that no gap exists between the bottom of the groove and the top of the ridge, the amount of plastic deformation of the metal material of the sheave member must be sufficiently large, which may cause cracking of the sheave member. By performing plastic flow bonding so that a gap is provided between the bottom of the groove and the top of the ridge, cracking of the sheave member can be suppressed.

[0016] [Item 4] The sheave for a continuously variable transmission according to Item 2 or 3, wherein the plurality of grooves include two first grooves extending in a circumferential direction of the boss member and a plurality of second grooves located between the two first grooves and extending in an axial direction of the boss member.

[0017] The plurality of grooves in the boss member preferably include two first grooves extending in the circumferential direction and a plurality of second grooves located between the two first grooves and extending in the axial direction of the boss member. The circumferentially extending first grooves engage with the protrusions of the sheave member, thereby preventing the sheave member from coming loose. Furthermore, the axially extending second grooves engage with the protrusions of the sheave member, thereby preventing the sheave member from rotating (twisting) relative to the boss member.

[0018] [Item 5] The sheave for a continuously variable transmission according to Item 4, wherein the length of each of the plurality of second grooves is 3 mm or more.

[0019] The portion of the mounting area of ​​the boss member where the multiple grooves are formed is the "joint portion" that actually contributes to the joint. As the length of the second groove increases, the length of the joint portion along the axial direction of the boss hole (which can be called the "engagement length") also increases, improving the joint strength and thereby suppressing tilt of the sheave member due to the force applied from the belt. Furthermore, as the length of the second groove increases, the meshing area between the boss member and the sheave member increases, thereby increasing the effect of suppressing rotation of the sheave member relative to the boss member and improving the heat dissipation of the sheave member. Specifically, the length of the second groove is preferably 3 mm or more.

[0020] [Item 6] The sheave for a continuously variable transmission according to Item 4 or 5, wherein the depth of each of the plurality of second grooves is 2 mm or less.

[0021] If the depth of the second groove is too large, the amount of plastic deformation of the metal material of the sheave member must be increased, which may cause cracking of the sheave member. From the viewpoint of preventing cracking of the sheave member, the depth of the second groove is preferably 2 mm or less.

[0022] [Item 7] The sheave for a continuously variable transmission according to any one of Items 4 to 6, wherein the ratio of length to depth of each of the plurality of second grooves is 5 or greater.

[0023] From the viewpoint of increasing the length of the joint and the meshing area between the boss member and the sheave member, the ratio of the length to the depth of the second groove is preferably 5 or more.

[0024] [Item 8] The sheave for a continuously variable transmission according to any one of Items 4 to 7, wherein the plurality of second grooves are arranged so that there is substantially no gap between two adjacent second grooves, and a ridge portion defined between the two adjacent second grooves has a radius of curvature of 0.5 mm or less.

[0025] When the plurality of second grooves are arranged so that there is substantially no gap between two adjacent second grooves, the ridge defined between two adjacent second grooves preferably has a radius of curvature of 0.5 mm or less, which increases the area of ​​the bonding interface and improves the bonding strength.

[0026] [Item 9] The sheave for a continuously variable transmission according to any one of Items 4 to 8, wherein the inclination angle of the side surface of each of the plurality of second grooves with respect to the depth direction is 30° or more and 60° or less.

[0027] The inclination angle of the side surface of the second groove with respect to the depth direction is preferably 30° to 60°, which facilitates plastic flow of the metal material of the sheave member and suppresses cracking of the sheave member.

[0028] [Item 10] The sheave for a continuously variable transmission according to any one of Items 4 to 9, wherein the bottom of each of the plurality of second grooves has a radius of curvature of 0.5 mm or less.

[0029] The bottom of the second groove preferably has a radius of curvature of 0.5 mm or less, which increases the area of ​​the bonding interface and improves the bonding strength.

[0030] [Item 11] The sheave for a continuously variable transmission according to any one of Items 4 to 10, wherein the depth of each of the plurality of first grooves is 2 mm or less.

[0031] From the viewpoint of suppressing cracking of the sheave member, the depth of the first groove is preferably 2 mm or less. From the viewpoint of preventing the sheave member from coming off, the depth of the first groove is preferably 0.5 mm or more.

[0032] [Item 12] The sheave for a continuously variable transmission according to any one of Items 2 to 11, wherein the inner circumferential surface of the boss member has a spline region where a spline structure is formed, and when the region where the plurality of grooves are formed in the attachment region is referred to as a joint, a clearance is provided between the joint and the spline region in the axial direction of the boss member.

[0033] The inner peripheral surface of the boss member may have a spline region in which a spline structure is formed for spline coupling with the shaft member inserted into the boss hole. It is preferable that a clearance be provided in the axial direction of the boss member between the spline region and the joint portion, which is the region in which multiple grooves are formed in the mounting region. When the sheave member is attached to the boss member by plastic flow bonding, a force that squeezes the joint portion of the boss member inward in the radial direction may act. Providing an axial clearance between the joint portion and the spline region makes it easier to ensure the boss member can slide relative to the shaft member.

[0034] [Item 13] The sheave for a continuously variable transmission according to Item 12, wherein the spline region includes a first spline portion having a first spline minor diameter and a second spline portion having a second spline minor diameter larger than the first spline minor diameter, and the second spline portion is disposed on the joint portion side relative to the first spline portion.

[0035] If a configuration is adopted in which the spline region includes a first spline portion having a first spline minor diameter and a second spline portion having a second spline minor diameter larger than the first spline minor diameter, and the second spline portion is positioned closer to the joint portion than the first spline portion, it becomes easier to ensure the sliding ability of the boss member relative to the shaft member.

[0036] [Item 14] The sheave for a continuously variable transmission according to any one of Items 2 to 13, wherein the first region of the mounting region includes a first press-fit portion into which the sheave member is press-fitted, the second region of the mounting region includes a second press-fit portion into which the sheave member is press-fitted, and a length of the second press-fit portion along the axial direction of the boss member is greater than a length of the first press-fit portion along the axial direction of the boss member.

[0037] From the viewpoint of suppressing tilt of the sheave member due to the force applied from the belt, it is preferable that the length of the second press-fit portion included in the second region of the mounting region is greater than the length of the first press-fit portion included in the first region of the mounting region.

[0038] [Item 15] The sheave for a continuously variable transmission according to any one of Items 1 to 14, wherein the back surface of the sheave member has a plurality of fins.

[0039] If the back surface of the sheave member has a plurality of fins, the heat dissipation performance can be further improved.

[0040] [Item 16] The sheave for a continuously variable transmission according to any one of Items 1 to 15, wherein the first metal material is an iron alloy, and the second metal material is an aluminum alloy.

[0041] By using an iron alloy as the first metal material and an aluminum alloy as the second metal material, it is possible to ensure sufficient strength and rigidity for the boss member while improving the heat dissipation properties and reducing the weight of the sheave member.

[0042] [Item 17] A continuously variable transmission comprising: a rotating shaft; and a movable sheave supported on the rotating shaft so as to be slidable in the axial direction of the rotating shaft, wherein the movable sheave is the sheave for a continuously variable transmission according to any one of items 1 to 16.

[0043] [Item 18] A straddle-type vehicle equipped with the continuously variable transmission according to Item 17.

[0044] [Item 19] A method for manufacturing a boss member comprising: a step (A) of preparing a boss member formed from a first metal material and having a boss hole; a step (B) of preparing a sheave member formed from a second metal material different from the first metal material, the sheave member including a sheave surface that receives a belt and a back surface located on the opposite side of the sheave surface; and a step (C) of attaching the sheave member to an attachment region that is a part of the outer peripheral surface of the boss member by plastic flow bonding, wherein when a direction parallel to the axial direction of the boss member and from one end of the boss member to the other end is referred to as a first direction, the step (C) is performed by pressurizing the sheave member and / or the boss member to move the sheave member relative to the boss member in the first direction, and the attachment region of the boss member has a stepped shape including a first region that is relatively small in diameter, a second region that is relatively large in diameter, and a step surface located at the boundary between the first region and the second region, The first region, the step surface, and the second region are arranged in this order along the first direction, and in step (C), the plastic flow bonding is performed by a portion of the sheave member abutting against the step surface of the boss member and plastically deforming.

[0045] In the method for manufacturing a sheave for a continuously variable transmission according to an embodiment of the present invention, a boss member and a sheave member made of different metal materials are prepared, so that desired and appropriate materials can be disposed in different portions of the sheave (specifically, the portion having the boss hole and the portion having the sheave surface that receives the belt). The sheave member is attached to an attachment region that is a part of the outer peripheral surface of the boss member by plastic flow bonding. Therefore, even if the sheave member and the boss member are made of different metal materials, they can be joined relatively easily, with high positional accuracy, and in a compact manner (i.e., without enlarging the layout).

[0046] In a manufacturing method according to an embodiment of the present invention, the mounting region, which is a portion of the outer peripheral surface of the boss member, has a stepped shape including a first region having a relatively small diameter, a second region having a relatively large diameter, and a stepped surface located at the boundary between the first and second regions. The first region, the stepped surface, and the second region are arranged in this order along the direction of relative movement of the sheave members (first direction) in step (C). In step (C), a portion of the sheave member abuts against the stepped surface of the boss member and plastically deforms, thereby achieving plastic flow bonding. Even in the completed sheave, the sheave member abuts against the stepped surface of the boss member, preventing the sheave member from coming loose due to the force applied from the belt during operation of the continuously variable transmission. In other words, the stepped surface not only causes plastic deformation of the sheave member during plastic flow bonding, but also functions as a retainer for the sheave member in the resulting sheave.

[0047] [Item 20] The manufacturing method according to Item 19, wherein the first region of the mounting region of the boss member has a plurality of grooves, and in step (C), a plurality of ridges that fit into the plurality of grooves are formed on the sheave member.

[0048] In a manufacturing method according to an embodiment of the present invention, for example, the first region of the mounting region of the boss member has a plurality of grooves, and in step (C), a plurality of ridges that fit into the plurality of grooves are formed in the sheave member, thereby performing mechanical joining. The plurality of ridges in the sheave member are formed by the sheave member abutting against the stepped surface of the boss member and plastically deforming the sheave member (more specifically, by the plastic flow of the metal material of the sheave member into the grooves of the boss member).

[0049] [Item 21] In the manufacturing method according to Item 19 or 20, in the step (C), when the amount of relative movement of the sheave member from the time when a part of the sheave member first comes into contact with the step surface to the time when the relative movement of the sheave member with respect to the boss member is completed is defined as a push-in length L, and the radial length of the step surface is defined as a step height D, a ratio L / D of the push-in length L to the step height D is 1.9 or more.

[0050] The greater the length (axial length of the boss hole) of the portion of the boss member attachment area that actually contributes to the joint (joint), the greater the joint strength. From the viewpoint of ensuring favorable plastic flow of the metal material of the sheave member throughout the entire joint, which has a long axial length, it is preferable that the ratio L / D of the push-in length L to the step height D be 1.9 or greater.

[0051] [Item 22] The manufacturing method according to any one of Items 19 to 21, wherein the step (C) is performed by pressing the sheave member in the first direction with a pressing jig while the boss member is supported by a first support jig, and the movement of the sheave member is completed in the step (C) when the pressing jig hits the first support jig.

[0052] Step (C) is performed, for example, by pressing the sheave member in the first direction with a pressing jig while the boss member is supported by a first support jig. In this case, it is preferable that the movement of the sheave member is completed when the pressing jig abuts against the first support jig in step (C). This makes it easy to keep the amount of movement of the sheave member (the pressing length L) constant.

[0053] [Item 23] The manufacturing method according to Item 22, wherein the step (C) is performed in a state where the back surface of the sheave member is elastically supported by a second support jig.

[0054] Step (C) is preferably performed in a state where the rear surface of the sheave member is elastically supported by the second support jig, thereby making it possible to suppress unintended deformation of the sheave member.

[0055] [Item 24] The manufacturing method according to any one of Items 19 to 23, wherein the step (C) is performed in a state where a centering jig is disposed so as to abut against both the inner peripheral surface of the boss member and the inner peripheral surface of the sheave member.

[0056] Step (C) is preferably performed with the centering jig positioned so as to abut against both the inner peripheral surfaces of the boss member and the sheave member, which makes it easier to align the axial centers of the boss member and the sheave member.

[0057] According to the embodiments of the present invention, it is possible to provide a suitable structure and manufacturing method for constructing a movable sheave for a continuously variable transmission from a plurality of members formed from different materials.

[0058] 1 is a left side view schematically showing a motorcycle 1 according to an embodiment of the present invention; FIG. 2 is a horizontal cross-sectional view schematically showing an engine unit 8 provided in the motorcycle 1; FIG. 3 is an enlarged view showing a primary pulley 41 and a sheave drive mechanism 44 of a continuously variable transmission 15 provided in the engine unit 8; FIG. 4 is an enlarged view showing the primary pulley 41 and the sheave drive mechanism 44; FIG. 5 is an enlarged view showing a secondary pulley 42 and a centrifugal clutch 45 of the continuously variable transmission 15; FIG. 6 is an enlarged view showing the secondary pulley 42 and the centrifugal clutch 45; FIG. 7 is a cross-sectional view schematically showing a sheave (first movable sheave) 100 of the primary pulley 41; FIG. 8 is a side view schematically showing the sheave 100, as viewed from the axially outer side; FIG. 9 is a side view schematically showing the sheave 100, as viewed from the axially inner side; FIG. 10 is a cross-sectional view schematically showing an attachment region AR and its vicinity; FIG. 11 is a perspective view showing a plurality of grooves 112 and their vicinity of a boss member 110; FIG. 12 is a cross-sectional view showing a boss member 110 prepared in a first preparation step; 1A and 1B are side views of a boss member 110 prepared in a first preparation step, as viewed from the axially outer side; FIG. 1C is a side view of a boss member 110 prepared in a first preparation step, as viewed from the axially inner side; FIG. 1D is a cross-sectional view of a sheave member 120 prepared in a second preparation step; FIG. 1E is a side view of a sheave member 120 prepared in a second preparation step, as viewed from the axially outer side; FIG. 1F is a side view of a sheave member 120 prepared in a second preparation step, as viewed from the axially inner side; and FIG. 1G is a diagram showing an example of an attachment step. The upper diagram shows the positional relationship between the sheave member 120 and the boss member 110 at time T1 when the second step surface SS2 of the sheave member 120 first contacts the first step surface SS1 of the boss member 110, and the lower diagram shows the positional relationship between the sheave member 120 and the boss member 110 at time T2 when the relative movement of the sheave member 120 with respect to the boss member 110 is completed. 1 is an enlarged cross-sectional view of a groove 112 and a ridge 124 fitted therein, showing a cross section perpendicular to the direction of extension of a first groove 112A. FIG. 2 is an enlarged cross-sectional view of a groove 112 and a ridge 124 fitted therein, showing a cross section perpendicular to the direction of extension of a second groove 112B. FIG. 3 is a cross-sectional view schematically showing a sheave 100.1 is a diagram for explaining a specific example of a method for manufacturing the sheave 100. FIG. 2 is a diagram for explaining a specific example of a method for manufacturing the sheave 100. FIG.

[0059] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description, a motorcycle is used as an example of a saddle-ride type vehicle according to an embodiment of the present invention, but the saddle-ride type vehicle according to an embodiment of the present invention is not limited to a motorcycle.

[0060] [Configuration of Motorcycle and Engine Unit] A motorcycle 1 according to an embodiment of the present invention will be described with reference to Figure 1. Figure 1 is a left side view that schematically shows the motorcycle 1. The motorcycle 1 shown in Figure 1 is a scooter-type motorcycle 1. Note that the motorcycle according to the embodiment of the present invention is not limited to the scooter-type motorcycle 1, and may be a street type, an off-road type, a moped type, or the like.

[0061] In the following description, the terms front, rear, left, and right refer to the front, rear, left, and right, respectively, as seen from the rider seated on the motorcycle 1. Additionally, the terms top and bottom refer to the top and bottom, respectively, when the motorcycle 1 is stopped on a horizontal plane.

[0062] As shown in FIG. 1 , the motorcycle 1 includes a body frame 2 , a body cover 3 , a front wheel 4 , a rear wheel 5 , a steering device 6 , a seat 7 , and an engine unit 8 .

[0063] The body cover 3 covers the body frame 2. The steering device 6 is supported by the body frame 2 so as to be rotatable left and right. The steering device 6 includes a front fork 11, a steering shaft 12, and a handle member 13.

[0064] The front forks 11 rotatably support the front wheel 4. The steering shaft 12 is connected to the front forks 11. The steering shaft 12 is supported by the body frame 2 so as to be rotatable left and right. A handle member 13 is connected to the steering shaft 12.

[0065] The seat 7 is disposed behind the handle member 13. The engine unit 8 is disposed below the seat 7. The engine unit 8 is supported by the body frame 2 so as to be able to swing up and down. The engine unit 8 rotatably supports the rear wheel 5. The engine unit 8 includes an engine 14 and a continuously variable transmission 15.

[0066] The continuously variable transmission 15 is disposed to the side of the engine 14. The continuously variable transmission 15 transmits the driving force from the engine 14 to the rear wheels 5.

[0067] 2 is a horizontal cross-sectional view schematically showing the engine unit 8. As shown in FIG. 2, the engine 14 includes a crankcase 21, a crankshaft 22, a cylinder body 23, a cylinder head 24, a piston 25, a connecting rod 26, and a valve train 27.

[0068] The crankshaft 22 is housed in the crankcase 21. The crankshaft 22 is rotatably supported by the crankcase 21 via bearings 28 and 29. The crankshaft 22 includes a first shaft end 22A and a second shaft end 22B. The continuously variable transmission 15 is connected to the first shaft end 22A. The generator 31 is connected to the second shaft end 22B.

[0069] The cylinder body 23 is connected to the crankcase 21. The cylinder head 24 is connected to the cylinder body 23. A connecting rod 26 and a piston 25 are disposed within the cylinder body 23. The piston 25 is connected to the crankshaft 22 via the connecting rod 26. An ignition device 32 is attached to the cylinder head 24. The valve mechanism 27 includes a camshaft 33. A cam chain 34 is wound around the camshaft 33 and the crankshaft 22. Rotation of the crankshaft 22 is transmitted to the camshaft 33 via the cam chain 34, causing the camshaft 33 to rotate. As a result, intake valves and exhaust valves (not shown) of the engine 14 are driven by the valve mechanism 27.

[0070] The continuously variable transmission 15 is electrically controlled to change the gear ratio in response to a command signal from a controller (not shown). In other words, the continuously variable transmission 15 is an electronically controlled transmission.

[0071] As shown in FIG. 2, the continuously variable transmission 15 includes a crankshaft 22, a primary pulley 41, a secondary pulley 42, a belt 43, a sheave drive mechanism 44, a centrifugal clutch 45, an output shaft 46, a reducer 47, and a transmission case 48.

[0072] The primary pulley 41 is connected to the crankshaft 22. The primary pulley 41 includes a V-shaped first groove 41A. The secondary pulley 42 is connected to the rear wheel 5 via an axle 49. The secondary pulley 42 includes a V-shaped second groove 42A.

[0073] The belt 43 is wound around the primary pulley 41 and the secondary pulley 42. The belt 43 has a trapezoidal cross section corresponding to the shapes of the first groove 41A and the second groove 42A. The secondary pulley 42 is connected to an output shaft 46 via a centrifugal clutch 45. The output shaft 46 is connected to an axle 49 via a reducer 47. The output shaft 46 is rotatably supported by a reducer case 51 (described later) via bearings 53 and 54. The axle 49 is rotatably supported by the reducer case 51 via bearings 55 and 56.

[0074] The reducer 47 includes a reducer case 51 and a gear 52. The reducer case 51 houses the gear 52. The gear 52 transmits the rotation of the output shaft 46 to the axle 49. Note that in Figure 2, only one gear 52 out of the multiple gears of the reducer 47 is shown, and the other gears are omitted.

[0075] The transmission case 48 axially covers the primary pulley 41, the secondary pulley 42, the belt 43, the centrifugal clutch 45, and the output shaft 46.

[0076] 3 and 4 are enlarged views showing the primary pulley 41 and the sheave drive mechanism 44. As shown in FIGS. 3 and 4, the primary pulley 41 includes a first movable sheave 100 and a first fixed sheave 58.

[0077] The first movable sheave 100 is supported relative to the crankshaft 22 so as to be movable in the axial direction of the crankshaft 22 (hereinafter simply referred to as the axial direction). The first movable sheave 100 is disposed axially inward (left side in FIG. 3 ) relative to the first fixed sheave 58.

[0078] The first moving sheave 100 is supported by the crankshaft 22 so as to be unable to rotate in the circumferential direction of the crankshaft 22. The first moving sheave 100 is fixed to the crankshaft 22 by a spline. The first moving sheave 100 rotates integrally with the crankshaft 22.

[0079] The first movable sheave 100 includes a first sheave member 120 and a first boss member 110. The first sheave member 120 is disposed opposite the first fixed sheave 58. The first sheave member 120 is fixed to the outer peripheral surface of the first boss member 110. A first groove 41A is provided between the first sheave member 120 and the first fixed sheave 58. The first boss member 110 extends in the axial direction from the first sheave member 120. The first boss member 110 includes a first boss hole 111. The first boss hole 111 extends in the axial direction. The crankshaft 22 extends through the first boss hole 111.

[0080] The crankshaft 22 includes an outer shaft 62. The outer shaft 62 is attached to the outer peripheral surface of the first shaft end 22A. The first movable sheave 100 is fixed to the outer shaft 62 by a spline. The outer shaft 62 extends through a first boss hole 111. A first bushing 63 and a second bushing 64 are press-fitted into the first boss hole 111. The first bushing 63 and the second bushing 64 are formed of a sliding material. The first bushing 63 and the second bushing 64 are disposed between the inner peripheral surface of the first boss hole 111 and the outer peripheral surface of the outer shaft 62. As the first movable sheave 100 moves axially, the first bushing 63 and the second bushing 64 slide axially relative to the outer shaft 62. The first boss hole 111 is filled with a lubricant such as grease. The gap between the first boss member 110 and the outer shaft 62 is sealed by oil seals 65 and 66.

[0081] The first fixed sheave 58 is fixed to the crankshaft 22. The first fixed sheave 58 is fixed to the crankshaft 22 by a nut 40. The first fixed sheave 58 is fixed to the crankshaft 22 so as to be immovable in the axial direction. The first fixed sheave 58 is fixed to the crankshaft 22 so as to be imrotatable relative to the crankshaft 22. The first fixed sheave 58 rotates integrally with the crankshaft 22.

[0082] The sheave drive mechanism 44 axially moves the first movable sheave 100. As shown in FIG.

[0083] The electric actuator 67 is, for example, an electric motor. The electric actuator 67 may be an actuator other than an electric motor. The electric actuator 67 includes a rotating shaft 70. The rotating shaft 70 is connected to a first driving member 68 via a gear 71. The rotation of the rotating shaft 70 is transmitted to the first driving member 68 via the gear 71.

[0084] 3 and 4, the first drive member 68 includes a first hole 72. The first hole 72 extends axially through the first drive member 68. The crankshaft 22 passes through the first hole 72. The first drive member 68 is supported on the crankshaft 22 via a bearing 50. The first drive member 68 is supported rotatably relative to the crankshaft 22. The first drive member 68 is supported so as to be immovable in the axial direction relative to the crankshaft 22.

[0085] The first driving member 68 includes a gear portion 73 and a feed screw portion 74. The gear portion 73 extends from the feed screw portion 74 in the radial direction of the crankshaft 22. The gear portion 73 meshes with the gear 71. The rotation of the rotary shaft 70 of the electric actuator 67 is transmitted to the gear portion 73 via the gear 71. This causes the first driving member 68 to rotate. The feed screw portion 74 extends in the axial direction from the gear portion 73. A first screw 75 is provided on the outer peripheral surface of the feed screw portion 74.

[0086] A crankcase cover 76 is attached to the crankcase 21. The crankcase cover 76 includes an opening 76A. The opening 76A is disposed facing the primary pulley 41. The second driving member 69 extends through the opening 76A of the crankcase 21. An oil seal 77 seals the gap between the second driving member 69 and the crankcase cover 76.

[0087] The second drive member 69 includes a second bore 78. The second bore 78 extends axially through the second drive member 69. The crankshaft 22 and the first boss member 110 extend through the second bore 78.

[0088] The second drive member 69 is supported by the first boss member 110 via a bearing 79. The second drive member 69 is rotatably supported by the first boss member 110. The second drive member 69 is supported by the first boss member 110 so as to be immovable in the axial direction. The second drive member 69 moves axially together with the first movable sheave 100. An oil seal 80 seals the gap between the second drive member 69 and the first boss member 110. A second screw 81 is provided on the inner circumferential surface of the second drive member 69. The second screw 81 meshes with the first screw 75. When the first drive member 68 rotates, the second drive member 69 moves axially as shown in FIG. 4 . This causes the first movable sheave 100 to move axially.

[0089] 5 and 6 are enlarged views showing the secondary pulley 42 and the centrifugal clutch 45. As shown in Figures 5 and 6, the secondary pulley 42 includes a second fixed sheave 82 and a second movable sheave 83. The second fixed sheave 82 is supported rotatably on the output shaft 46. The second fixed sheave 82 is supported immovably in the axial direction on the output shaft 46.

[0090] The second fixed sheave 82 includes a second sheave member 84 and a second boss member 85. The second sheave member 84 is disposed opposite the second movable sheave 83. A second groove 42A is provided between the second sheave member 84 and the second movable sheave 83. The second boss member 85 extends in the axial direction from the second sheave member 84. The second boss member 85 includes a second boss hole 86. The second boss hole 86 extends in the axial direction through the second boss member 85.

[0091] The output shaft 46 is rotatably supported by the transmission case 48 via a bearing 95. The output shaft 46 extends through the second boss hole 86. A bushing 91 is press-fitted into the second boss hole 86. The bushing 91 is made of a sliding material. The bushing 91 is disposed between the inner peripheral surface of the second boss hole 86 and the outer peripheral surface of the output shaft 46.

[0092] The second boss member 85 is rotatably supported on the output shaft 46 by a bushing 91 and a bearing 92. A lubricant such as grease is filled in the second boss hole 86. An oil seal 93 seals the gap between the second boss member 85 and the output shaft 46.

[0093] The second moving sheave 83 is disposed axially outward (to the right in FIG. 5 ) relative to the second fixed sheave 82. The second moving sheave 83 is supported non-rotatably relative to the second boss member 85. The second moving sheave 83 rotates integrally with the second fixed sheave 82. The second moving sheave 83 is supported axially movably relative to the second boss member 85. For example, the second moving sheave 83 is fixed to the second boss member 85 by a spline. A spring 87 is disposed between the second moving sheave 83 and the centrifugal clutch 45. The spring 87 biases the second moving sheave 83 toward the second fixed sheave 82.

[0094] When the vehicle speed is lower than a predetermined coupling speed, the centrifugal clutch 45 is in a disengaged state in which the continuously variable transmission 15 is disconnected from the rear wheels 5, as shown in Fig. 5. When the vehicle speed is equal to or higher than the coupling speed, the centrifugal clutch 45 is in an engaged state in which the continuously variable transmission 15 is connected to the rear wheels 5, as shown in Fig. 6.

[0095] The centrifugal clutch 45 includes a drive plate 88, a clutch shoe 89, and a clutch outer 90. The drive plate 88 is fixed to the second boss member 85. The drive plate 88 rotates integrally with the second boss member 85.

[0096] The clutch shoe 89 is connected to the drive plate 88. The clutch shoe 89 rotates integrally with the drive plate 88. The clutch shoe 89 is supported so as to be movable in the radial direction relative to the drive plate 88. The clutch shoe 89 is biased radially inward by a clutch spring (not shown).

[0097] The clutch outer 90 is fixed to the output shaft 46 by a nut 94. The clutch outer 90 rotates integrally with the output shaft 46. The clutch outer 90 covers the clutch shoes 89 in the radial direction.

[0098] When the vehicle speed is slower than a predetermined engagement speed, the clutch shoes 89 are separated from the clutch outer 90 by the biasing force of the clutch spring. Therefore, the centrifugal clutch 45 is in a disengaged state, and the rotation of the secondary pulley 42 is not transmitted to the output shaft 46. When the vehicle speed is equal to or higher than the engagement speed, the clutch shoes 89 move radially outward due to centrifugal force against the biasing force of the clutch spring. This brings the clutch shoes 89 into contact with the clutch outer 90, and the centrifugal clutch 45 is in an engaged state. When the centrifugal clutch 45 is in an engaged state, the rotation of the secondary pulley 42 is transmitted to the output shaft 46 via the drive plate 88, the clutch shoes 89, and the clutch outer 90.

[0099] In the continuously variable transmission 15 having the above-described configuration, when the vehicle speed is equal to or higher than the coupling speed, the centrifugal clutch 45 is engaged. As a result, the rotation of the crankshaft 22 is transmitted to the rear wheel 5 via the primary pulley 41, the belt 43, the secondary pulley 42, the centrifugal clutch 45, the output shaft 46, the reducer 47, and the axle 49. This allows the motorcycle 1 to travel.

[0100] Furthermore, the gear ratio of the continuously variable transmission 15 is electrically controlled by moving the first movable sheave 100 with the sheave drive mechanism 44. The gear ratio of the continuously variable transmission 15 means the ratio of the rotational speed of the crankshaft 22 to the rotational speed of the output shaft 46.

[0101] Specifically, when the electric actuator 67 rotates the first drive member 68 in a certain direction, the second drive member 69 moves axially outward as shown in FIG. 4 . This causes the first movable sheave 100 to move axially outward together with the second drive member 69. When the first movable sheave 100 moves axially outward, the width of the first groove 41A between the first movable sheave 100 and the first fixed sheave 58 decreases. This increases the diameter of the portion of the belt 43 wound around the primary pulley 41 (hereinafter referred to as the first winding diameter). As the first winding diameter increases, the diameter of the portion of the belt 43 wound around the secondary pulley 42 (hereinafter referred to as the second winding diameter) decreases. This decreases the gear ratio. In this case, as shown in FIG. 6 , the second movable sheave 83 moves axially outward against the biasing force of the spring 87, and the width of the second groove 42A increases.

[0102] When the electric actuator 67 rotates the first drive member 68 in the reverse direction, the second drive member 69 moves axially inward, as shown in FIG. 4 . This causes the first movable sheave 100 to move axially inward together with the second drive member 69. When the first movable sheave 100 moves axially inward, the width of the first groove 41A between the first movable sheave 100 and the first fixed sheave 58 increases. This reduces the first winding diameter. When the first winding diameter decreases, the second winding diameter increases. This increases the gear ratio. In this case, as shown in FIG. 5 , the second movable sheave 83 moves axially inward due to the biasing force of the spring 87, and the width of the second groove 42A decreases.

[0103] Next, the structure of the first movable sheave 100 of the primary pulley 41 will be described in more detail with reference to Figures 7, 8, and 9. As can be seen from the above description, the first movable sheave 100 is supported by the crankshaft (rotating shaft) 22 so as to be slidable in the axial direction of the crankshaft 22. In the following description, the first movable sheave 100 will be simply referred to as the "sheave." Figure 7 is a cross-sectional view schematically showing the sheave 100, and Figures 8 and 9 are side views schematically showing the sheave 100. Figure 8 is a view of the sheave 100 viewed from the axially outer side, while Figure 9 is a view of the sheave 100 viewed from the axially inner side.

[0104] As shown in Figures 7, 8 and 9, the sheave 100 comprises a first boss member (hereinafter simply referred to as the "boss member") 110 and a first sheave member (hereinafter simply referred to as the "sieve member") 120.

[0105] The boss member 110 and the sheave member 120 are formed from different metal materials. The materials of the boss member 110 and the sheave member 120 may each be a pure metal or an alloy. In this specification, "homogeneous" metal materials means that the main component elements (the metal element that is most abundant) of the metal materials are the same, and "heterogeneous" metal materials means that the main component elements of the metal materials are different. For example, pure aluminum and aluminum alloys are the same metal material, and carbon steel and stainless steel are the same metal material. Furthermore, aluminum alloys and stainless steel are dissimilar metal materials. In the following description, the metal material forming the boss member 110 may be referred to as the "first metal material," and the metal material forming the sheave member 120 may be referred to as the "second metal material." In this embodiment, a material that is more easily plastically deformed than the first metal material (i.e., softer than the first metal material) is used as the second metal material. In other words, the first metallic material is made of a material that is less susceptible to plastic deformation than the second metallic material (i.e., harder than the second metallic material).

[0106] The boss member 110 is generally cylindrical and has a first boss hole (hereinafter simply referred to as "boss hole") 111. The central axis of the boss hole 111 substantially coincides with the central axis of the crankshaft 22. The inner circumferential surface 110is of the boss member 110 has a spline region SR in which a spline structure (specifically, spline grooves sg) is formed. The boss member 110 is made of, for example, an iron alloy.

[0107] The sheave member 120 is generally disk-shaped with a through hole in the center, and includes a sheave surface 121 and a back surface 122. The sheave surface 121 faces the first fixed sheave 58 and receives the belt 43. The back surface 122 is located opposite the sheave surface 121. The back surface 122 has a plurality of fins 123. Each of the plurality of fins 123 extends in the radial direction. The sheave member 120 is formed from, for example, an aluminum alloy.

[0108] The sheave member 120 is attached by plastic flow bonding to an attachment area AR, which is part of the outer circumferential surface 110os of the boss member 110. The attachment area AR is located at one end of the boss member 110 (the end on the side of the first fixed sheave 58 in the continuously variable transmission 15).

[0109] Here, the structure of the attachment area AR and its vicinity will be described with further reference to Fig. 10. Fig. 10 is an enlarged cross-sectional view showing the attachment area AR and its vicinity.

[0110] The mounting area AR has a first region R1 and a second region R2 having different diameters. The first region R1 has a smaller diameter than the second region R2. In other words, the second region R2 has a larger diameter than the first region R1. A radially extending step surface SS1 exists at the boundary between the first region R1 and the second region R2. Thus, the mounting area AR has a stepped shape including the first region R1 having a relatively small diameter, the second region R2 having a relatively large diameter, and the step surface SS1 located at the boundary between the first region R1 and the second region R2.

[0111] The first region R1, the step surface SS1, and the second region R2 are arranged in this order from the sheave surface 121 side toward the back surface 122 side. The sheave member 121 abuts against the step surface SS1.

[0112] The inner circumferential surface 120is of the sheave member 120 has a third region R3 and a fourth region R4 having different diameters. The third region R3 has a smaller diameter than the fourth region R4. In other words, the fourth region R4 has a larger diameter than the third region R3. A radially extending step surface SS2 exists at the boundary between the third region R3 and the fourth region R4. Thus, the inner circumferential surface 120is of the sheave member 120 includes the third region R3 having a relatively small diameter, the fourth region R4 having a relatively large diameter, and the step surface SS2 located at the boundary between the third region R3 and the fourth region R4, and the step surface SS2 abuts against the step surface SS1 of the boss member 110. In the following description, the step surface SS1 of the boss member 110 may be referred to as the "first step surface," and the step surface SS2 of the sheave member 120 may be referred to as the "second step surface."

[0113] Here, the first region R1 of the mounting region AR of the boss member 110 has a plurality of grooves 112, and the third region R3 of the sheave member 120 has a plurality of ridges (linear protrusions) 124 that fit into these grooves 112, thereby forming a mechanical joint. As will be described later, the ridges 124 of the sheave member 120 are formed when the sheave member 120 abuts against the step surface SS1 of the boss member 110 and plastically deforms (more specifically, the metal material of the sheave member 120 undergoes plastic flow and flows into the grooves 112 of the boss member 110) when the sheave member 120 is mounted to the boss member 110. In the following description, the region JP in the mounting region AR where the plurality of grooves 112 are formed will be referred to as the "joint portion."

[0114] Also, in the example shown, the first region R1 of the mounting region AR includes a first press-fit portion PF1 into which the sheave member 120 is pressed, and the second region R2 of the mounting region AR includes a second press-fit portion PF2 into which the sheave member 120 is pressed.

[0115] Fig. 11 is a perspective view showing the plurality of grooves 112 and the vicinity thereof of the boss member 110. As shown in Fig. 11, the plurality of grooves 112 includes two first grooves 112A and a plurality of second grooves 112B.

[0116] Each of the two first grooves 112A extends in the circumferential direction of the boss member 110. The cross-sectional shape of each of the first grooves 112A is substantially triangular. In other words, the first grooves 112A are so-called V-grooves.

[0117] Each of the multiple second grooves 112B is located between two first grooves 112A and extends in the axial direction of the boss member 110. Each second groove 112B is continuous with two first grooves 112A. The cross-sectional shape of each second groove 112B is substantially triangular. In other words, the second grooves 112B are also what is known as V-grooves.

[0118] The sieve 100 having the above-described configuration can be manufactured by the method described below.

[0119] First, a boss member 110 made of a first metallic material is prepared (first preparation step). Separately from the first preparation step, a sheave member 120 made of a second metallic material different from the first metallic material is prepared (second preparation step). As already explained, the second metallic material is a material that is more susceptible to plastic deformation than the first metallic material.

[0120] 12A, 12B, and 12C are diagrams showing the boss member 110 prepared in the first preparation step. Fig. 12A is a cross-sectional view of the boss member 110, and Figs. 12B and 12C are side views of the boss member 110.

[0121] The boss member 110 prepared in the first preparation step has substantially the same shape as the boss member 110 in the finished sheave 100. Here, if a direction D1 (see FIG. 12A ) that is parallel to the axial direction of the boss member 110 and extends from one end 110a of the boss member 110 (the axially outer end in the continuously variable transmission 15) toward the other end 110b (the axially inner end in the continuously variable transmission 15) is referred to as a “first direction,” the first region R1, first step surface SS1, and second region R2 of the mounting region AR of the boss member 110 are arranged in this order along the first direction D1.

[0122] 13A, 13B, and 13C are diagrams showing the sheave member 120 prepared in the second preparation step. Fig. 13A is a cross-sectional view of the sheave member 120, and Figs. 13B and 13C are side views of the sheave member 120.

[0123] The sheave member 120 prepared in the second preparation process has a shape slightly different from that of the sheave member 120 in the finished sheave 100. The inner circumferential surface 120is of the prepared sheave member 120 includes a third region R3 having a relatively small diameter, a fourth region R4 having a relatively large diameter, and a second step surface SS2 located at the boundary between the third region R3 and the fourth region R4. However, the inner circumferential surface 120is of the prepared sheave member 120 does not have a protrusion 124. Furthermore, the position of the second step surface SS2 in the prepared sheave member 120 differs from the position of the second step surface SS2 in the finished sheave 100. In the prepared sheave member 120, the axial length of the third region R3 is greater than the axial length of the third region R3 in the finished sheave 100. In other words, in the prepared sheave member 120, the length along the axial direction of the fourth region R4 is shorter than the length along the axial direction of the fourth region R3 in the finished sheave 100. Therefore, it can be said that the position of the second step surface SS2 in the prepared sheave member 120 is shifted toward the back surface 122 with respect to the position of the second step surface SS2 in the finished sheave 100.

[0124] After the first and second preparation steps, the sheave member 120 is attached to the attachment area AR, which is a part of the outer circumferential surface 110os of the boss member 110, by plastic flow bonding (attachment step). This attachment step is performed by applying pressure to the sheave member 120 and / or the boss member 110 to move the sheave member 120 relative to the boss member 110 in the first direction D1.

[0125] An example of the mounting process is shown in Fig. 14. In the example shown in Fig. 14, the mounting process is performed by applying pressure to the sheave member 120 and moving it in the first direction D1. In the mounting process, a portion of the sheave member 120 abuts against the step surface SS1 of the mounting region AR of the boss member 120 and undergoes plastic deformation, thereby performing plastic flow bonding.

[0126] Figure 15 shows, in the upper part, the positional relationship between the sheave member 120 and the boss member 110 at time T1 when the second step surface SS2 of the sheave member 120 (part of the sheave member 120) first comes into contact with the first step surface SS1 of the boss member 110, and, in the lower part, the positional relationship between the sheave member 120 and the boss member 110 at time T2 when the relative movement of the sheave member 120 with respect to the boss member 110 is completed.

[0127] 15, the plastic deformation of the sheave member 120 forms a ridge 124 that fits into the groove 112 of the boss member 110, thereby achieving a mechanical joint. Also, a comparison of the upper and lower rows of FIG. 15 reveals that the position of the second step surface SS2 is shifted toward the sheave surface 121 due to the plastic deformation of the sheave member 120.

[0128] The lower part of Figure 15 shows the original shape of the sheave member 120 (i.e., the shape without plastic deformation) using imaginary lines (two-dot chain lines). The distance L from the original position SS2' of the second step surface SS2 to the position of the second step surface SS2 after plastic deformation is the relative movement amount of the sheave member 120 from time T1 to time T2 described above, and will be referred to below as the "push-in length." Furthermore, the radial length D of the first step surface SS1 (which is also the radial length of the second step surface SS2) will be referred to below as the "step height."

[0129] 14 illustrates an example in which the sheave member 120 is pressurized and moved in the first direction D1, but the installation process is not limited to this. The boss member 110 may be pressurized and moved in the direction opposite to the first direction D1 (the second direction). Alternatively, the sheave member 120 may be pressurized and moved in the first direction D1, and the boss member 110 may be pressurized and moved in the second direction.

[0130] In this manner, the sheave 100 is obtained. After the attachment step, machining or the like may be performed on the boss member 110 and / or the sheave member 120, if necessary.

[0131] As described above, in the sheave 100 according to the embodiment of the present invention, the boss member 110 and the sheave member 120 are formed from different metal materials, allowing desired and appropriate materials to be disposed in different portions of the sheave 100 (specifically, the portion having the boss hole 111 and the portion having the sheave surface 121 that receives the belt 43). The sheave member 120 is attached to the attachment area AR, which is a portion of the outer peripheral surface 110os of the boss member 110, by plastic flow bonding. Therefore, even though the sheave member 120 and the boss member 110 are formed from different metal materials, they can be joined relatively easily with high positional accuracy and in a compact manner (i.e., without enlarging the layout). In contrast, joining the boss member and the sheave member using other joining methods (e.g., riveting or casting) can result in complicated manufacturing, low positional accuracy during joining, and enlargement of the layout.

[0132] In the sheave 100 according to the embodiment of the present invention, the mounting region AR, which is a portion of the outer peripheral surface 110os of the boss member 110, has a stepped shape including a first region R1 having a relatively small diameter, a second region R2 having a relatively large diameter, and a step surface SS1 located at the boundary between the first region R1 and the second region R2. The first region R1, step surface SS1, and second region R2 are arranged in this order from the sheave surface 121 toward the back surface 122, and the sheave member 120 abuts against the step surface SS1. This prevents the sheave member 120 from coming loose due to a force (a force acting in the first direction D1) applied by the belt 43 during operation of the continuously variable transmission 15. In other words, the step surface SS1 functions as a retainer for the sheave member 120.

[0133] While Fig. 10 and other figures illustrate an example in which no gap exists between the groove 112 of the boss member 110 and the ridge 124 of the sheave member 120, as shown in Figs. 16A and 16B , a gap ga may be provided between the bottom 112b of each groove 112 and the top 124t of the ridge 124 that fits into that groove 112. Fig. 16A shows a cross section perpendicular to the extension direction of the first groove 112A, and Fig. 16B shows a cross section perpendicular to the extension direction of the second groove 112B. In the configuration shown in Fig. 16A , a gap ga is provided between the bottom 112b of the first groove 112A and the top 124t of the ridge 124 that fits into the first groove 112A. In the configuration shown in FIG. 16B, a gap ga is provided between the bottom 112b of the second groove 112B and the top 124t of the protrusion 124 that fits into the second groove 112B.

[0134] From the perspective of preventing cracking of the sheave member 120 during plastic flow bonding, it is preferable to provide a gap ga between the bottom 112b of each groove 112 and the top 124t of the ridge 124 that fits into that groove 112, as shown in Figures 16A and 16B. If plastic flow bonding is performed so that no gap ga exists between the bottom 112b of the groove 112 and the top 124t of the ridge 124, the amount of plastic deformation of the metal material of the sheave member 120 must be sufficiently large, which may cause cracking of the sheave member 120. By performing plastic flow bonding so that a gap ga is provided between the bottom 112b of the groove 112 and the top 124t of the ridge 124, cracking of the sheave member 120 can be suppressed.

[0135] As illustrated, the plurality of grooves 112 of the boss member 120 preferably include two first grooves 112A extending in the circumferential direction and a plurality of second grooves 112B located between the two first grooves 112A and extending in the axial direction of the boss member 110. The ribs 124 of the sheave member 120 are fitted into the first grooves 112A extending in the circumferential direction, thereby preventing the sheave member 120 from coming loose. Furthermore, the ribs 124 of the sheave member 120 are fitted into the second grooves 112B extending in the axial direction of the boss member 110, thereby preventing the sheave member 120 from rotating (twisting) relative to the boss member 110.

[0136] Within the mounting region AR of the boss member 110, the joint portion JP (see FIG. 10 ), where multiple grooves 112 are formed, actually contributes to the joint. As the length L2 (see FIG. 16A ) of the second groove 112B increases, the length of the joint portion JP along the axial direction of the boss hole 111 (which can be referred to as the “engagement length”) also increases, improving the joint strength and thereby suppressing tilt of the sheave member 120 due to the force applied from the belt 43. Furthermore, as the length L2 of the second groove 112B increases, the meshing area between the boss member 110 and the sheave member 120 increases, thereby enhancing the effect of suppressing rotation of the sheave member 120 relative to the boss member 110 and improving the heat dissipation of the sheave member 120. Specifically, the length L2 of the second groove 112B is preferably 3 mm or greater.

[0137] If the depth D2 (see FIG. 16B ) of the second groove 112B is too large, it is necessary to increase the amount of plastic deformation of the metal material of the sheave member 120, which raises concerns about cracking of the sheave member 120. From the viewpoint of suppressing cracking of the sheave member 120, it is preferable that the depth D2 of the second groove 112B be 2 mm or less.

[0138] From the viewpoint of increasing the length of the joint JP and increasing the meshing area between the boss member 110 and the sheave member 120, it is preferable that the ratio L2 / D2 of the length L2 to the depth D2 of the second groove 112B be 5 or greater.

[0139] 16B, when the plurality of second grooves 112B are arranged so that there is substantially no gap between two adjacent second grooves 112B, the ridge portion pp defined between two adjacent second grooves 112B preferably has a curvature radius of 0.5 mm or less, which increases the area of ​​the bonding interface and improves the bonding strength.

[0140] The inclination angle θ of the side surface of the second groove 112B with respect to the depth direction is preferably 30° or more and 60° or less, which makes it easier for the metal material of the sheave member 120 to undergo plastic flow and suppresses cracking of the sheave member 120.

[0141] The bottom 112b of the second groove 112B preferably has a radius of curvature of 0.5 mm or less, which increases the area of ​​the bonding interface and improves the bonding strength.

[0142] From the viewpoint of preventing the sheave member 120 from coming loose, the depth D1 of the first groove 112A (see FIG. 16A) is preferably 0.5 mm or more. Furthermore, from the viewpoint of suppressing cracking of the sheave member 120, the depth D1 of the first groove 112A is preferably 2 mm or less.

[0143] As already explained, the inner peripheral surface 110is of the boss member 110 has a spline region SP where a spline structure is formed for spline coupling with a shaft member inserted into the boss hole 111. As shown in FIG. 17 , it is preferable to provide a clearance in the axial direction of the boss member 110 between the joint JP (the region where the multiple grooves 112 are formed) of the attachment region AR and the spline region SP. When the sheave member 120 is attached to the boss member 110 by plastic flow bonding, a force that squeezes the joint JP of the boss member 110 inward in the radial direction may act. Providing an axial clearance between the joint JP and the spline region SP makes it easy to ensure the boss member 110 can slide relative to the shaft member.

[0144] 17, the spline region SP includes a first spline portion SP1 having a first spline minor diameter and a second spline portion SP2 having a second spline minor diameter larger than the first spline minor diameter, and the second spline portion SP2 is disposed on the joint portion JP side of the first spline portion SP1. By adopting such a configuration, it is easier to ensure the slidability of the boss member 110 relative to the shaft member.

[0145] From the viewpoint of suppressing tilt of the sheave member 120 due to the force applied from the belt 43, it is preferable that the length of the second press-fit portion PF2 included in the second region R2 of the mounting region AR is greater than the length of the first press-fit portion PF1 included in the first region R1 of the mounting region AR.

[0146] In the configuration illustrated in Fig. 9 and other figures, the rear surface 122 of the sheave member 120 has a plurality of fins 123. When the rear surface 122 of the sheave member 120 has a plurality of fins 123, heat dissipation can be further improved. Note that the number, shape, size, etc. of the fins 123 are not limited to those illustrated in Fig. 9.

[0147] There are no particular limitations on the first metallic material forming the boss member 110 and the second metallic material forming the sheave member 120. By using an iron alloy as the first metallic material and an aluminum alloy as the second metallic material, it is possible to improve the heat dissipation and reduce the weight of the sheave member 120 while ensuring sufficient strength and rigidity for the boss member 110. For example, mechanical structural carbon steel can be suitably used as the iron alloy, and for example, an Al-Si alloy can be suitably used as the aluminum alloy.

[0148] As a combination of the first metal material and the second metal material, in addition to the above-mentioned combination of iron alloy and aluminum alloy, a combination of iron alloy and magnesium alloy, a combination of titanium alloy and aluminum alloy, a combination of iron alloy and copper alloy, etc. may be used.

[0149] As already explained, the greater the length (the length along the axial direction of the boss hole 111) of the portion of the attachment region AR of the boss member 110 that actually contributes to the joint (the joint portion JP), the greater the joint strength. From the viewpoint of favorably plastically flowing the metal material of the sheave member 120 throughout the entire joint portion JP, which has a large axial length, it is preferable that the ratio L / D of the push-in length L to the step height D be greater than a certain level, and specifically, it is preferable that it be 1.9 or greater.

[0150] Here, a more specific example of a method for manufacturing the sheave 100 will be described with reference to FIGS. 18A and 18B.

[0151] Although not mentioned above, the area of ​​the outer peripheral surface 110os of the boss member 110 other than the mounting area AR can function as a support area SR (see FIG. 18A ) for supporting the boss member 110 during the mounting process. The support area SR includes a fifth region R5 having a relatively large diameter, a sixth region R6 having a relatively small diameter, and a step surface (third step surface) SS3 located between the fifth region R5 and the sixth region R6 and extending in the radial direction. The fifth region R5, the third step surface SS3, and the sixth region R6 are arranged in this order along the first direction D1.

[0152] The attachment process can be performed, for example, as shown in FIG. 18B, by pressing the sheave member 120 in the first direction D1 with a pressing jig 220 while the boss member 110 is supported by a first support jig 210.

[0153] The first support jig 210 has a support hole 211 having approximately the same diameter as the sixth region R6 of the support region SR of the boss member 110. With the boss member 110 fitted into the support hole 211, the third step surface SS3 of the boss member 110 abuts against the upper end surface 210a of the first support jig 210, whereby the boss member 110 is supported by the first support jig 210.

[0154] The pressing jig 220 has a pressing surface 220a that abuts against the sheave surface 121 of the sheave member 120 to press the sheave member 120, and an abutting surface 220b that protrudes further toward the first support jig 210 than the pressing surface 220a. In the attachment process, the abutting surface 220b of the pressing jig 220 abuts against the first support jig 210, thereby completing the movement of the sheave member 120.

[0155] In this manner, in the attachment process, it is preferable that the movement of the sheave member 120 is completed when the pressing jig 220 abuts against the first support jig 210. This makes it easy to keep the movement amount (push-in length L) of the sheave member 120 constant.

[0156] 18B , a second support jig 230 capable of elastically supporting the supported member is also used in the attachment process. The specific configuration of the second support jig 230 is not particularly limited. The second support jig 230 includes, for example, a gas spring.

[0157] The mounting process is performed in a state in which the rear surface 122 of the sheave member 120 is elastically supported by the second support jig 230, thereby making it possible to suppress unintended deformation of the sheave member 120.

[0158] 18B, a centering jig 240 is also used in the attachment process. The centering jig 240 is substantially cylindrical, and an outer peripheral surface 240os of the centering jig 240 includes a first portion p1 that abuts against an inner peripheral surface 110is of the boss member 110 and a second portion p2 that abuts against an inner peripheral surface 120is of the sheave member 120.

[0159] The installation process is carried out with the centering jig 240 positioned so that it abuts both the inner surface 110is of the boss member 110 and the inner surface 120is of the sheave member 120, making it easier to align the axial center of the boss member 110 with the axial center of the sheave member 120.

[0160] As described above, the sheave 100 for a continuously variable transmission according to an embodiment of the present invention is a sheave 100 for a continuously variable transmission comprising: a boss member 110 formed from a first metal material and having a boss hole 111; and a sheave member 120 formed from a second metal material different from the first metal material, the sheave member 120 including a sheave surface 121 that receives a belt 43 and a back surface 122 located opposite the sheave surface 121, and the sheave member 120 is attached to an attachment region AR, which is part of the outer peripheral surface 110os of the boss member 110, by plastic flow bonding. The mounting region AR has a stepped shape including a first region R1 having a relatively small diameter, a second region R2 having a relatively large diameter, and a step surface SS1 located at the boundary between the first region R1 and the second region R2, and the first region R1, the step surface SS1, and the second region R2 are arranged in this order from the sheave surface 121 side toward the back surface 122 side, and the sheave member 120 abuts against the step surface SS1.

[0161] In the continuously variable transmission sheave 100 according to the embodiment of the present invention, the boss member 110 and the sheave member 120 are formed from different metal materials, so that desired and appropriate materials can be disposed in different portions of the sheave 100 (specifically, the portion having the boss hole 111 and the portion having the sheave surface 121 that receives the belt 43). The sheave member 120 is attached to the attachment region AR, which is part of the outer peripheral surface 110os of the boss member 110, by plastic flow bonding. Therefore, even though the sheave member 120 and the boss member 110 are formed from different metal materials, they can be joined relatively easily, with high positional accuracy, and in a compact manner (i.e., without enlarging the layout).

[0162] In the continuously variable transmission sheave 100 according to the embodiment of the present invention, the mounting region AR, which is a portion of the outer peripheral surface 110os of the boss member 110, has a stepped shape including a first region R1 having a relatively small diameter, a second region R2 having a relatively large diameter, and a stepped surface SS1 located at the boundary between the first region R1 and the second region R2. The first region R1, the stepped surface SS1, and the second region R2 are arranged in this order from the sheave surface 121 side toward the back surface 122 side, and the sheave member 120 abuts against the stepped surface SS1. This prevents the sheave member 120 from coming loose due to the force applied from the belt 43 during operation of the continuously variable transmission 15. In other words, the stepped surface SS1 functions as a retainer for the sheave member 120.

[0163] In one embodiment, the first region R1 of the mounting region AR of the boss member 110 has a plurality of grooves 112, and the sheave member 120 has a plurality of ridges 124 that fit into the plurality of grooves 112.

[0164] In the continuously variable transmission sheave 100 according to the embodiment of the present invention, for example, the first region R1 of the mounting region AR of the boss member 110 has a plurality of grooves 112, and the sheave member 120 has a plurality of ridges 124 that fit into these grooves 112, thereby achieving mechanical joining. The ridges of the sheave member 120 can be formed when the sheave member 120 abuts against the step surface SS1 of the boss member 110 and plastically deforms (more specifically, the metal material of the sheave member 120 undergoes plastic flow and flows into the grooves 112 of the boss member 110) when the sheave member 120 is mounted to the boss member 110.

[0165] In one embodiment, a gap ga is provided between the bottom 112 b of each of the plurality of grooves 112 and the top 124 t of the protrusion 124 that fits into the groove 112 .

[0166] From the perspective of preventing cracking of the sheave member 120 during plastic flow bonding, it is preferable to provide a gap ga between the bottom 112b of each groove 112 and the top 124t of the ridge 124 that fits into that groove 112. If plastic flow bonding is performed so that no gap ga exists between the bottom 112b of the groove 112 and the top 124t of the ridge 124, the amount of plastic deformation of the metal material of the sheave member 120 must be sufficiently large, which may cause cracking of the sheave member 120. By performing plastic flow bonding so that a gap ga is provided between the bottom 112b of the groove 112 and the top 124t of the ridge 124, cracking of the sheave member 120 can be suppressed.

[0167] In one embodiment, the plurality of grooves 112 include two first grooves 112A extending circumferentially around the boss member 110, and a plurality of second grooves 112B located between the two first grooves 112A and extending axially around the boss member 110.

[0168] The plurality of grooves 112 of the boss member 110 preferably include two first grooves 112A extending in the circumferential direction and a plurality of second grooves 112B located between the two first grooves 112A and extending in the axial direction of the boss member 110. The ribs 124 of the sheave member 120 are fitted into the first grooves 112A extending in the circumferential direction, thereby preventing the sheave member 120 from coming loose. Furthermore, the ribs 124 of the sheave member 120 are fitted into the second grooves 112B extending in the axial direction of the boss member 110, thereby preventing the sheave member 120 from rotating (twisting) relative to the boss member 110.

[0169] In one embodiment, the length L2 of each of the plurality of second grooves 112B is 3 mm or greater.

[0170] Within the mounting region AR of the boss member 110, the portion JP where the multiple grooves 112 are formed is the "joint portion" that actually contributes to the joint. As the length L2 of the second groove 112B increases, the length of the joint portion JP along the axial direction of the boss hole 111 (which can be referred to as the "engagement length") also increases, improving joint strength and thereby suppressing tilt of the sheave member 120 due to force applied from the belt 43. Furthermore, as the length L2 of the second groove 112B increases, the meshing area between the boss member 110 and the sheave member 120 increases, thereby enhancing the effect of suppressing rotation of the sheave member 120 relative to the boss member 110 and improving the heat dissipation of the sheave member 120. Specifically, the length L2 of the second groove 112B is preferably 3 mm or greater.

[0171] In one embodiment, the depth D2 of each of the plurality of second grooves 112B is 2 mm or less.

[0172] If the depth D2 of the second groove 112B is too large, it is necessary to increase the amount of plastic deformation of the metal material of the sheave member 120, which raises concerns about cracking of the sheave member 120. From the viewpoint of suppressing cracking of the sheave member 120, it is preferable that the depth D2 of the second groove 112B be 2 mm or less.

[0173] In one embodiment, the ratio L2 / D2 of the length L2 to the depth D2 of each of the second grooves 112B is 5 or greater.

[0174] From the viewpoint of increasing the length of the joint JP and increasing the meshing area between the boss member 110 and the sheave member 120, it is preferable that the ratio L2 / D2 of the length L2 to the depth D2 of the second groove 112B be 5 or greater.

[0175] In one embodiment, the plurality of second grooves 112B are arranged so that there is substantially no gap between two adjacent second grooves 112B, and the ridge portion pp defined between the two adjacent second grooves 112B has a radius of curvature of 0.5 mm or less.

[0176] When the multiple second grooves 112B are arranged so that there is substantially no gap between two adjacent second grooves 112B, the ridge portion pp defined between two adjacent second grooves 112B preferably has a curvature radius of 0.5 mm or less, which increases the area of ​​the bonding interface and improves the bonding strength.

[0177] In one embodiment, the inclination angle θ of the side surface of each of the second grooves 112B with respect to the depth direction is equal to or greater than 30° and equal to or less than 60°.

[0178] The inclination angle θ of the side surface of the second groove 112B with respect to the depth direction is preferably 30° or more and 60° or less, which makes it easier for the metal material of the sheave member 120 to undergo plastic flow and suppresses cracking of the sheave member 120.

[0179] In one embodiment, the bottom 112b of each of the plurality of second grooves 112B has a radius of curvature of 0.5 mm or less.

[0180] The bottom 112b of the second groove 112B preferably has a radius of curvature of 0.5 mm or less, which increases the area of ​​the bonding interface and improves the bonding strength.

[0181] In one embodiment, the depth D1 of each of the plurality of first grooves 112A is 2 mm or less.

[0182] From the viewpoint of suppressing cracking of the sheave member 120, the depth D1 of the first groove 112A is preferably 2 mm or less. From the viewpoint of preventing the sheave member 120 from coming off, the depth D1 of the first groove 112A is preferably 0.5 mm or more.

[0183] In one embodiment, the inner surface 110is of the boss member 110 has a spline region SP in which a spline structure is formed, and when the region in the mounting region AR in which the multiple grooves 112 are formed is called a joint JP, a clearance is provided in the axial direction of the boss member 110 between the joint JP and the spline region SP.

[0184] The inner peripheral surface 110is of the boss member 110 may have a spline region SP in which a spline structure is formed for spline coupling with a shaft member inserted into the boss hole 111. It is preferable to provide a clearance in the axial direction of the boss member 110 between the spline region SP and a joint portion JP, which is an area in the mounting region AR where multiple grooves 112 are formed. When the sheave member 120 is attached to the boss member 110 by plastic flow bonding, a force that squeezes the joint portion JP of the boss member 110 inward in the radial direction may act. Providing an axial clearance between the joint portion JP and the spline region SP makes it easier to ensure the boss member 110 can slide relative to the shaft member.

[0185] In one embodiment, the spline region SP includes a first spline portion SP1 having a first spline minor diameter and a second spline portion SP2 having a second spline minor diameter larger than the first spline minor diameter, and the second spline portion SP2 is disposed on the joint portion JP side relative to the first spline portion SP1.

[0186] By adopting a configuration in which the spline region SP includes a first spline portion SP1 having a first spline minor diameter and a second spline portion SP2 having a second spline minor diameter larger than the first spline minor diameter, and the second spline portion SP2 is positioned on the joint portion JP side relative to the first spline portion SP1, it becomes easier to ensure the sliding ability of the boss member 110 relative to the shaft member.

[0187] In one embodiment, the first region R1 of the mounting area AR includes a first press-fit portion PF1 into which the sheave member 120 is pressed, and the second region R2 of the mounting area AR includes a second press-fit portion PF2 into which the sheave member 120 is pressed, and the length of the second press-fit portion PF2 along the axial direction of the boss member 110 is greater than the length of the first press-fit portion PF1 along the axial direction of the boss member 110.

[0188] From the viewpoint of suppressing tilt of the sheave member 120 due to the force applied from the belt 43, it is preferable that the length of the second press-fit portion PF2 included in the second region R2 of the mounting region AR is greater than the length of the first press-fit portion PF1 included in the first region R1 of the mounting region AR.

[0189] In one embodiment, the back surface 122 of the sheave member 120 has a plurality of fins 123 .

[0190] If the rear surface 122 of the sheave member 120 has a plurality of fins 123, the heat dissipation performance can be further improved.

[0191] In one embodiment, the first metal material is an iron alloy, and the second metal material is an aluminum alloy.

[0192] By using an iron alloy as the first metal material and an aluminum alloy as the second metal material, it is possible to ensure sufficient strength and rigidity for the boss member 110 while improving the heat dissipation properties and reducing the weight of the sheave member 120.

[0193] The continuously variable transmission 15 according to an embodiment of the present invention comprises a rotating shaft (crankshaft 22) and a movable sheave 100 supported on the rotating shaft so as to be slidable in the axial direction of the rotating shaft, and the movable sheave 100 is a sheave 100 for a continuously variable transmission having any of the configurations described above.

[0194] The straddle-type vehicle according to the embodiment of the present invention includes the continuously variable transmission 15 having the above-described configuration.

[0195] A manufacturing method of a sheave 100 for a continuously variable transmission according to an embodiment of the present invention includes the steps of: (A) preparing a boss member 110 formed from a first metal material and having a boss hole 111; (B) preparing a sheave member 120 formed from a second metal material different from the first metal material, the sheave member 120 including a sheave surface 121 that receives a belt 43 and a back surface 122 located opposite the sheave surface 121; and (C) attaching the sheave member 120 to an attachment region AR, which is part of the outer peripheral surface 110os of the boss member 110, by plastic flow bonding. When a direction D1 parallel to the axial direction of the boss member 110 and directed from one end 110a to the other end 110b of the boss member 110 is referred to as a first direction, the step (C) is performed by applying pressure to the sheave member 120 and / or the boss member 110 to move the sheave member 120 in the first direction D1 relative to the boss member 110. The attachment region AR of the boss member 110 has a stepped shape including a first region R1 having a relatively small diameter, a second region R2 having a relatively large diameter, and a step surface SS1 located at the boundary between the first region R1 and the second region R2, and the first region R1, the step surface SS1, and the second region R2 are arranged in this order along the first direction D1. In the step (C), a portion of the sheave member 120 abuts against the step surface SS1 of the boss member 110 and plastically deforms, thereby performing the plastic flow bonding.

[0196] In the manufacturing method of the continuously variable transmission sheave 100 according to the embodiment of the present invention, the boss member 110 and the sheave member 120 are prepared from different metal materials, so that desired and appropriate materials can be disposed in different portions of the sheave 100 (specifically, the portion having the boss hole 111 and the portion having the sheave surface 121 that receives the belt 43). The sheave member 120 is attached to the attachment region AR, which is part of the outer peripheral surface 110os of the boss member 110, by plastic flow bonding. Therefore, even if the sheave member 120 and the boss member 110 are formed from different metal materials, they can be joined relatively easily, with high positional accuracy, and in a compact manner (i.e., without enlarging the layout).

[0197] In addition, in a manufacturing method according to an embodiment of the present invention, the mounting region AR, which is a portion of the outer peripheral surface 110os of the boss member 110, has a stepped shape including a first region R1 having a relatively small diameter, a second region R2 having a relatively large diameter, and a step surface SS1 located at the boundary between the first region R1 and the second region R2. The first region R1, the step surface SS1, and the second region R2 are arranged in this order along the direction of relative movement of the sheave member 120 (first direction D1) in step (C). In step (C), a portion of the sheave member 120 abuts against the step surface SS1 of the boss member 110 and plastically deforms, thereby performing plastic flow bonding. Even in a completed state of the sheave 100, the sheave member 120 abuts against the step surface SS1 of the boss member 110, preventing the sheave member 120 from coming loose due to the force applied from the belt 43 during operation of the continuously variable transmission 15. That is, the step surface SS1 not only causes plastic deformation of the sheave member 120 during plastic flow bonding, but also functions as a retainer for the sheave member 120 in the obtained sheave 100.

[0198] In one embodiment, the first region R1 of the mounting region AR of the boss member 110 has a plurality of grooves 112, and in step (C), a plurality of protrusions 124 that fit into the plurality of grooves 112 are formed on the sheave member 120.

[0199] In a manufacturing method according to an embodiment of the present invention, for example, the first region R1 of the mounting region AR of the boss member 110 has a plurality of grooves 112, and in step (C), mechanical joining is performed by forming a plurality of ridges 124 in the sheave member 120 that fit into the plurality of grooves 112. The plurality of ridges 124 of the sheave member 120 are formed when the sheave member 120 abuts against the step surface SS1 of the boss member 110, causing the sheave member 120 to plastically deform (more specifically, when the metal material of the sheave member 120 undergoes plastic flow and flows into the grooves 112 of the boss member 110).

[0200] In one embodiment, in step (C), when the relative movement of the sheave member 120 from time T1 when a part of the sheave member 120 first comes into contact with the step surface SS1 to time T2 when the relative movement of the sheave member 120 with respect to the boss member 110 is completed is defined as the push-in length L, and the radial length of the step surface SS1 is defined as the step height D, the ratio L / D of the push-in length L to the step height D is 1.9 or more.

[0201] The greater the length (the length along the axial direction of the boss hole 111) of the portion of the attachment region AR of the boss member 110 that actually contributes to the joint (the joint portion JP), the greater the joint strength. From the viewpoint of favorably plastically flowing the metal material of the sheave member 120 throughout the entire joint portion JP, which has a long axial length, it is preferable that the ratio L / D of the push-in length L to the step height D be 1.9 or greater.

[0202] In one embodiment, the step (C) is performed by pressing the sheave member 120 in the first direction D1 with a pressing jig 220 while the boss member 110 is supported by a first support jig 210, and in the step (C), the movement of the sheave member 120 is completed when the pressing jig 220 hits the first support jig 210.

[0203] Step (C) is performed, for example, by pressing the sheave member 120 in the first direction D1 with a pressing jig 220 while the boss member 110 is supported by the first support jig 210. In this case, it is preferable that the movement of the sheave member 120 is completed in step (C) when the pressing jig 220 abuts against the first support jig 210. This makes it easy to keep the amount of movement (pressed length L) of the sheave member 120 constant.

[0204] In one embodiment, the step (C) is performed in a state where the back surface 122 of the sheave member 120 is elastically supported by a second support jig 230 .

[0205] It is preferable that the step (C) be performed in a state in which the back surface 122 of the sheave member 120 is elastically supported by the second support jig 230. This makes it possible to suppress unintended deformation of the sheave member 120.

[0206] In one embodiment, the step (C) is performed in a state where a centering jig 240 is positioned so as to abut against both the inner circumferential surface 110is of the boss member 110 and the inner circumferential surface 120is of the sheave member 120.

[0207] Step (C) is preferably performed in a state where the centering jig 240 is positioned so as to abut against both the inner circumferential surface 110is of the boss member 110 and the inner circumferential surface 120is of the sheave member 120. This makes it easy to align the axial center of the boss member 110 with the axial center of the sheave member 120.

[0208] According to an embodiment of the present invention, it is possible to provide a suitable structure and manufacturing method for constructing a movable sheave for a continuously variable transmission from a plurality of members formed from different materials. The sheave for a continuously variable transmission according to an embodiment of the present invention is widely used in continuously variable transmissions for various saddle-ride type vehicles.

[0209] 1: motorcycle, 15: continuously variable transmission, 22: crankshaft, 41: primary pulley, 42: secondary pulley, 43: belt, 44: sheave drive mechanism, 100: sheave (first movable sheave), 110: boss member, 111: boss hole, 112: groove, 112A: first groove, 112B: second groove, 120: sheave member, 121: sheave surface, 122: back surface, 123: fin, 124: protrusion, AR: attachment region, R1: first region, R2: second region, SS1: step surface (first step surface), JP: joint portion

Claims

1. A sheave for a continuously variable transmission comprising: a boss member formed from a first metallic material and having a boss hole; and a sheave member formed from a second metallic material different from the first metallic material, the sheave member including a sheave surface that receives a belt and a back surface located on the opposite side of the sheave surface, wherein the sheave member is attached to an attachment region that is part of the outer peripheral surface of the boss member by plastic flow bonding, the attachment region having a stepped shape including a first region that is relatively small in diameter, a second region that is relatively large in diameter, and a stepped surface located at the boundary between the first region and the second region, the first region, the stepped surface, and the second region being arranged in this order from the sheave surface side toward the back surface side, and the sheave member abutting against the stepped surface.

2. A sheave for a continuously variable transmission as set forth in claim 1, wherein the first region of the mounting region of the boss member has a plurality of grooves, and the sheave member has a plurality of ridges that fit into the plurality of grooves.

3. A sheave for a continuously variable transmission as set forth in claim 2, wherein a gap is provided between the bottom of each of said plurality of grooves and the top of the ridge that fits into said groove.

4. A sheave for a continuously variable transmission as set forth in claim 2 or 3, wherein the plurality of grooves include two first grooves extending in the circumferential direction of the boss member and a plurality of second grooves located between the two first grooves and extending in the axial direction of the boss member.

5. The sheave for a continuously variable transmission according to claim 4, wherein the length of each of the plurality of second grooves is 3 mm or more.

6. A sheave for a continuously variable transmission according to claim 4 or 5, wherein the depth of each of the plurality of second grooves is 2 mm or less.

7. A sheave for a continuously variable transmission according to any one of claims 4 to 6, wherein the ratio of length to depth of each of said plurality of second grooves is 5 or greater.

8. A sheave for a continuously variable transmission as set forth in any one of claims 4 to 7, wherein the plurality of second grooves are arranged so that there is substantially no gap between any two adjacent second grooves, and the ridge defined between any two adjacent second grooves has a radius of curvature of 0.5 mm or less.

9. A sheave for a continuously variable transmission according to any one of claims 4 to 8, wherein the inclination angle of the side surface of each of the plurality of second grooves relative to the depth direction is between 30° and 60°.

10. A sheave for a continuously variable transmission according to any one of claims 4 to 9, wherein the bottom of each of the plurality of second grooves has a radius of curvature of 0.5 mm or less.

11. A sheave for a continuously variable transmission according to any one of claims 4 to 10, wherein the depth of each of the plurality of first grooves is 2 mm or less.

12. A sheave for a continuously variable transmission as set forth in any one of claims 2 to 11, wherein the inner peripheral surface of the boss member has a spline region in which a spline structure is formed, and when the region in the mounting region in which the plurality of grooves are formed is called a joint, a clearance is provided between the joint and the spline region in the axial direction of the boss member.

13. A sheave for a continuously variable transmission as set forth in claim 12, wherein the spline region includes a first spline portion having a first spline minor diameter and a second spline portion having a second spline minor diameter larger than the first spline minor diameter, and the second spline portion is disposed on the joint side relative to the first spline portion.

14. A sheave for a continuously variable transmission as described in any one of claims 2 to 13, wherein the first region of the mounting region includes a first press-fit portion into which the sheave member is press-fitted, the second region of the mounting region includes a second press-fit portion into which the sheave member is press-fitted, and the length of the second press-fit portion along the axial direction of the boss member is greater than the length of the first press-fit portion along the axial direction of the boss member.

15. A sheave for a continuously variable transmission according to any one of claims 1 to 14, wherein the back surface of the sheave member has a plurality of fins.

16. A sheave for a continuously variable transmission according to any one of claims 1 to 15, wherein the first metal material is an iron alloy, and the second metal material is an aluminum alloy.

17. A continuously variable transmission comprising: a rotating shaft; and a movable sheave supported on the rotating shaft so as to be slidable in the axial direction of the rotating shaft, wherein the movable sheave is a sheave for a continuously variable transmission as defined in any one of claims 1 to 16.

18. A straddle-type vehicle equipped with the continuously variable transmission according to claim 17.

19. A method for manufacturing a boss member, comprising: a step (A) of preparing a boss member formed from a first metallic material and having a boss hole; a step (B) of preparing a sheave member formed from a second metallic material different from the first metallic material, the sheave member including a sheave surface that receives a belt and a back surface located opposite the sheave surface; and a step (C) of attaching the sheave member to an attachment region that is a part of the outer peripheral surface of the boss member by plastic flow bonding, wherein a direction parallel to the axial direction of the boss member and from one end of the boss member to the other end is referred to as a first direction, and wherein the step (C) is carried out by applying pressure to the sheave member and / or the boss member to move the sheave member relative to the boss member in the first direction, and the attachment region of the boss member has a stepped shape including a first region having a relatively small diameter, a second region having a relatively large diameter, and a step surface located at the boundary between the first region and the second region, The first region, the step surface, and the second region are arranged in this order along the first direction, and in step (C), the plastic flow bonding is performed by a portion of the sheave member abutting against the step surface of the boss member and plastically deforming.

20. A manufacturing method as set forth in claim 19, wherein the first region of the mounting region of the boss member has a plurality of grooves, and in step (C), a plurality of ridges that fit into the plurality of grooves are formed on the sheave member.

21. A manufacturing method as described in claim 19 or 20, wherein in step (C), the amount of relative movement of the sheave member from the time when a part of the sheave member first comes into contact with the step surface to the time when the relative movement of the sheave member with respect to the boss member is completed is defined as a push-in length L, and the radial length of the step surface is defined as a step height D, and the ratio L / D of the push-in length L to the step height D is 1.9 or more.

22. A manufacturing method as described in any one of claims 19 to 21, wherein step (C) is performed by pressing the sheave member in the first direction with a pressing jig while the boss member is supported by a first support jig, and in step (C), the movement of the sheave member is completed when the pressing jig hits the first support jig.

23. A manufacturing method according to claim 22, wherein step (C) is carried out in a state in which the rear surface of the sheave member is elastically supported by a second support jig.

24. A manufacturing method described in any one of claims 19 to 23, wherein step (C) is performed with a centering jig positioned so that it abuts against both the inner surface of the boss member and the inner surface of the sheave member.

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