Pulley and belt type continuously variable transmission

Abstract

To provide a pulley which achieves improvement of abrasion resistance of an inner peripheral surface of a fixed boss.SOLUTION: A drive pulley 110 comprises: a fixed sheave 111 that has a fixed sheave surface 111S which contacts with a V belt 130; a fixed boss 116 that extends rightward from the fixed sheave 111 and is formed in a cylindrical shape; a movable sheave 112 that has a movable sheave surface 112S disposed in a position such that the movable sheave surface 112S contacts with the V belt 130 and faces the fixed sheave surface 111S, and can move close to and away from the fixed sheave 111; and a movable boss 117 that projects rightward from the movable sheave 112, is formed in a cylindrical shape, is externally fitted on the fixed boss 116, and slides along an outer peripheral surface 116B of the fixed boss 116. A crankshaft 68 is inserted into the fixed boss 116, and an oxide film is formed on an inner peripheral surface 116A of the fixed boss 116.SELECTED DRAWING: Figure 3

Description

【Technical Field】 【0001】 The present invention relates to a pulley used in a belt-type continuously variable transmission and a belt-type continuously variable transmission provided with the pulley. 【Background Art】 【0002】 Conventionally, as a transmission used in vehicles such as motorcycles, a belt-type continuously variable transmission is known. The belt-type continuously variable transmission includes a driving pulley, a driven pulley, and a V-belt (driving belt) wound around the driving pulley and the driven pulley. The driving pulley and the driven pulley each include a fixed sheave and a movable sheave that can approach and separate from the fixed sheave. For example, Patent Document 1 discloses a V-belt continuously variable transmission including a driving pulley provided on a crankshaft, a driven pulley (corresponding to the driven pulley) provided on a driven shaft, and a V-belt wound around the driving pulley and the driven pulley. 【Prior Art Documents】 【Patent Documents】 【0003】 【Patent Document 1】 Japanese Unexamined Patent Application Publication No. 2010-236647 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 Incidentally, the drive pulley and driven pulley each comprise a fixed sheave having a fixed sheave surface in contact with the drive belt, a cylindrical fixed boss, and a movable sheave having a movable sheave surface in contact with the drive belt, and sliding along the outer diameter side of the fixed boss, allowing it to approach and move away from the fixed sheave. The fixed boss of the drive pulley is positioned abutting against the fixed sheave. The fixed boss of the driven pulley is formed integrally with the fixed sheave and protrudes from the fixed sheave. Here, since the movable sheave moves axially around the outer circumference of the fixed bosses of the drive pulley and driven pulley, the strength and wear resistance to sliding of the fixed bosses were increased by, for example, applying hard chrome plating after high-frequency induction hardening. However, due to the properties of hard chrome plating and high-frequency induction hardening, it was difficult to harden the inner surface of the fixed boss, resulting in the problem of low wear resistance of the inner surface of the fixed boss. 【0005】 The present invention has been made in view of the above, and its object is to provide a pulley with improved wear resistance of the inner circumferential surface of the fixed boss, and a belt-type continuously variable transmission equipped therewith. [Means for solving the problem] 【0006】 The pulley according to the present invention is a pulley used in a belt-type continuously variable transmission, and the pulley comprises a fixed sheave having a fixed sheave surface that contacts a drive belt, a fixed boss extending from the fixed sheave in a first direction and formed in a cylindrical shape, a movable sheave having a movable sheave surface that contacts the drive belt and is positioned opposite the fixed sheave surface and is capable of approaching and moving away from the fixed sheave, and a movable boss extending from the movable sheave in the first direction and formed in a cylindrical shape, which fits onto the fixed boss and slides along the outer circumferential surface of the fixed boss, a shaft is inserted into the fixed boss, and an oxide film is formed on the inner circumferential surface of the fixed boss. 【0007】 According to the pulley of the present invention, an oxide film is formed on the inner circumferential surface of the fixed boss into which the shaft is inserted. As a result, the sliding properties and wear resistance of the inner circumferential surface of the fixed boss are relatively high. This makes it possible to suppress wear on the inner circumferential surface of the fixed boss even if, for example, force is applied to the shaft and the inner circumferential surface of the fixed boss rubs against the shaft. [Effects of the Invention] 【0008】 According to the present invention, it is possible to provide a pulley in which the wear resistance of the inner circumferential surface of the fixed boss is improved. [Brief explanation of the drawing] 【0009】 [Figure 1] Figure 1 is a side view of a motorcycle according to one embodiment. [Figure 2] Figure 2 is a cross-sectional view of an engine unit according to one embodiment. [Figure 3] Figure 3 is a cross-sectional view of a drive pulley according to one embodiment. [Figure 4] Figure 4 is a cross-sectional view of a driven pulley according to one embodiment. [Figure 5] Figure 5 is a cross-sectional view showing the structure around the torque cam groove of a driven pulley according to one embodiment. [Figure 6] Figure 6 is a plan view of the driven pulley at low speed according to one embodiment. [Figure 7] Figure 7 is a plan view of a driven pulley at high speed according to one embodiment. [Modes for carrying out the invention] 【0010】 The following describes embodiments of the pulley and the belt-type continuously variable transmission equipped with the pulley according to the present invention with reference to the drawings. Here, a so-called scooter-type motorcycle equipped with a belt-type continuously variable transmission will be used as an example, but the motorcycle of the present invention is not limited to a so-called scooter-type motorcycle. Naturally, the embodiments described herein are not intended to particularly limit the present invention. In addition, the same reference numerals are used for members and parts that perform the same function, and redundant explanations are omitted or simplified as appropriate. 【0011】 Figure 1 is a side view of the motorcycle 10. In the following description, unless otherwise specified, front, rear, left, right, top, and bottom refer to the front, rear, left, right, top, and bottom of the motorcycle 10 as seen from the perspective of the driver. The symbols F, Rr, L, R, U, and D in the drawing represent the front, rear, left, right, top, and bottom, respectively. 【0012】 As shown in Figure 1, the motorcycle 10 is equipped with an engine unit 50. 【0013】 As shown in Figure 2, the engine unit 50 comprises an engine 60, a crankcase 61 housing a crankshaft 68 (described later), a belt-type continuously variable transmission 100 (hereinafter referred to as CVT 100), and a transmission case 70 housing the CVT 100. In this embodiment, the engine 60 and the CVT 100 are integrated to constitute the engine unit 50, but the engine 60 and the CVT 100 may be separate. 【0014】 As shown in Figure 2, the engine 60 is a single-cylinder engine with a single cylinder. The engine 60 comprises a cylinder block 62 extending forward from the crankcase 61 and coupled to the crankcase 61, a cylinder head 63 connected to the front of the cylinder block 62, and a cylinder head cover 64 connected to the front of the cylinder head 63. A cylinder 65 is formed inside the cylinder block 62. 【0015】 As shown in Fig. 2, a piston 66 is slidably accommodated in a cylinder 65. The piston 66 is connected to a crankshaft 68 via a connecting rod 67. The crankshaft 68 extends leftward and rightward and is supported by a crankcase 61. The driving force of the crankshaft 68 is transmitted to a rear wheel 44 (see Fig. 1) via a CVT 100. The crankshaft 68 is an example of a shaft. 【0016】 In the present embodiment, the crankcase 61, the cylinder block 62, the cylinder head 63, and the cylinder head cover 64 are separate bodies and are assembled to each other. However, they do not necessarily have to be separate bodies and may be integrally formed as appropriate. For example, the crankcase 61 and the cylinder block 62 may be integrally formed, or the cylinder block 62 and the cylinder head 63 may be integrally formed. Also, the cylinder head 63 and the cylinder head cover 64 may be integrally formed. 【0017】 The specific configuration of the crankcase 61 is not limited in any way. Here, the crankcase 61 is composed of a plurality of members. However, the crankcase 61 may be composed of a single member. Here, the case that houses the crankshaft 68 and the case that houses the CVT 100 are referred to as the crankcase 61 and the transmission case 70, respectively. The crankcase 61 and the transmission case 70 do not necessarily have to be independent members from each other, and one member may constitute part or all of the crankcase 61 and the transmission case 70. For example, a part of the member that constitutes the crankcase 61 may constitute a part of the transmission case 70. 【0018】 As shown in Fig. 2, the CVT 100 includes a driving pulley 110 that is a driving-side pulley, a driven pulley 120 that is a driven-side pulley, and a V-belt 130 wound around the driving pulley 110 and the driven pulley 120. The V-belt 130 is an example of a driving belt. 【0019】 As shown in Fig. 2, the drive pulley 110 has a fixed sheave 111, a movable sheave 112, a fixed boss 116 disposed to abut against the fixed sheave 111, and a movable boss 117 extending rightward from the movable sheave 112. In the drive pulley 110 of the present embodiment, the rightward direction is an example of the first direction. The fixed sheave 111 and the movable sheave 112 are attached to the left end portion of the crankshaft 68, and the drive pulley 110 rotates together with the crankshaft 68. The fixed sheave 111 is located to the left, i.e., outward, of the movable sheave 112. The fixed sheave 111 is immovable in the axial direction of the crankshaft 68. The movable sheave 112 is movable in the axial direction of the crankshaft 68. The movable sheave 112 is configured to be able to approach and separate from the fixed sheave 111. A V-shaped belt groove for supporting the V-belt 130 is formed by the fixed sheave 111 and the movable sheave 112. 【0020】 As shown in Fig. 3, the fixed sheave 111 is formed in a disc shape. The fixed sheave 111 has a fixed sheave surface 111S that contacts the V-belt 130. The fixed sheave surface 111S is inclined outward (here, leftward) as it goes from the radially inner side to the radially outer side. The fixed boss 116 extends rightward from the fixed sheave 111. The fixed boss 116 is disposed at the central portion of the fixed sheave 111. The fixed boss 116 is disposed on the surface 111F of the fixed sheave 111 where the fixed sheave surface 111S is formed. The fixed boss 116 protrudes rightward from the surface 111F. The fixed boss 116 is formed in a cylindrical shape. The fixed boss 116 is formed, for example, from carbon steel. The crankshaft 68 is inserted into the fixed boss 116. An oxide film is formed on the inner peripheral surface 116A of the fixed boss 116. Therefore, for example, fretting wear that may occur between the crankshaft 68 and the inner peripheral surface 116A of the fixed boss 116 can be suppressed, and rattling and seizure of the crankshaft 68 can be suppressed. Also, an oxide film is formed on the outer peripheral surface 116B of the fixed boss 116. 【0021】 The oxide film formed on the inner circumferential surface 116A and outer circumferential surface 116B of the fixed boss 116 contains, for example, oxides derived from the metal constituting the fixed boss 116. The oxide film contains, for example, triiron tetroxide (Fe3O4). The oxide film is formed, for example, by gas soft nitriding followed by steam treatment. The maximum height Rz of the surface on which the oxide film is formed is, for example, 1 μm to 12.5 μm (e.g., 1 μm to 3.2 μm). The maximum height Rz is a value measured according to JIS B 0601:2013. In addition, compounds derived from gas soft nitriding (e.g., Fe3N or Fe4N) may be present between the inner circumferential surface 116A and outer circumferential surface 116B of the fixed boss 116 and the oxide film. 【0022】 As shown in Figure 3, the movable sheave 112 is formed in a disc shape. The movable sheave 112 has a movable sheave surface 112S that contacts the V-belt 130. The movable sheave surface 112S is inclined outward (to the right in this case) as it moves from the radially inward to the radially outward. The movable sheave surface 112S is positioned opposite the fixed sheave surface 111S. The V-belt 130 is sandwiched between the movable sheave surface 112S and the fixed sheave surface 111S. The movable boss 117 is connected to the movable sheave 112. The movable boss 117 is formed integrally with the movable sheave 112. The movable boss 117 is located in the central part of the movable sheave 112. The movable boss 117 is located on the back surface 112R of the movable sheave 112, which is on the opposite side (to the right in this case) from the movable sheave surface 112S. The movable boss 117 protrudes to the right from the back surface 112R. The movable boss 117 is formed in a cylindrical shape. The movable boss 117 is fitted onto the fixed boss 116 and slides along the outer circumferential surface 116B of the fixed boss 116. 【0023】 As shown in Figure 2, the driven pulley 120 includes a fixed sheave 121, a movable sheave 122, a fixed boss 126 projecting to the left from the fixed sheave 121, and a movable boss 127 projecting to the left from the movable sheave 122. In the driven pulley 120 of this embodiment, the left is an example of a first direction. The fixed sheave 121 and the movable sheave 122 are mounted on the main shaft 72, and the driven pulley 120 rotates with the main shaft 72 after the centrifugal clutch 150 engages. The fixed sheave 121 is located to the right, i.e., inward, of the movable sheave 122. The fixed sheave 121 is immovable in the axial direction of the main shaft 72. The movable sheave 122 is movable in the axial direction of the main shaft 72 along the outer circumference of the fixed boss 126. The movable sheave 122 is configured to move closer to and further away from the fixed sheave 121. A V-shaped belt groove is formed by the fixed sheave 121 and the movable sheave 122 to support the V-belt 130. The main shaft 72 is connected to the rear axle 76, which rotatably supports the rear wheel, via a gear mechanism 74. 【0024】 As shown in Figure 4, the fixed sheave 121 is formed in a disc shape. The fixed sheave 121 has a fixed sheave surface 121S that contacts the V-belt 130. The fixed sheave surface 121S is inclined outward (to the right in this case) from the radially inward to the radially outward. The fixed boss 126 is connected to the fixed sheave 121. The fixed boss 126 is fixed to the fixed sheave 121, for example, by welding. The fixed boss 126 is located in the central part of the fixed sheave 121. The fixed boss 126 is positioned on the surface 121F of the fixed sheave 121 on which the fixed sheave surface 121S is formed. The fixed boss 126 protrudes to the left from the surface 121F. The fixed boss 126 is formed in a cylindrical shape. The main shaft 72 is inserted into the fixed boss 126. Here, the main shaft 72 is an example of a shaft. An oxide film is formed on the inner circumferential surface 126A of the fixed boss 126. An oxide film is formed on the outer circumferential surface 126B of the fixed boss 126. The formed oxide films are similar to the oxide films formed on the inner circumferential surface 116A of the fixed boss 116, etc. 【0025】 As shown in Figure 5, the driven pulley 120 includes a torque cam groove 118 formed through the movable boss 127, a guide pin 128 inserted into the torque cam groove 118, and a pin hole 129 formed in the fixed boss 126. The guide pin 128 is inserted into the torque cam groove 118. The torque cam groove 118 guides the movement of the movable sheave 122. The torque cam groove 118 generates a thrust that grips the V-belt 130, transmitting the driving force from the V-belt 130 to the rear axle 76. As shown in Figure 6, the torque cam groove 118 extends in the circumferential direction of the movable boss 127. The torque cam groove 118 is formed in a substantially oval shape. The movable sheave 122 can move relative to the fixed sheave 121 in the axial direction of the main shaft 72 along the torque cam groove 118. The movable sheave 122 can rotate relative to the fixed sheave 121 along the torque cam groove 118. 【0026】 As shown in Figure 5, a guide roller 128G is attached to the guide pin 128. The guide roller 128G is rotatably mounted around the guide pin 128. The guide roller 128G is a component that allows the guide pin 128 to move smoothly along the torque cam groove 118. The guide roller 128G is a component that suppresses misalignment between the guide pin 128 and the torque cam groove 118. The pin hole 129 penetrates the fixed boss 126 radially. The guide pin 128 is inserted into the pin hole 129. The guide pin 128 is fixed to the pin hole 129. The guide pin 128 is fixed to the inner circumferential surface 126C of the fixed boss 126 that partitions the pin hole 129. An oxide film similar to the oxide film formed on the inner circumferential surface 116A of the fixed boss 116 is formed on the inner circumferential surface 126C of the fixed boss 126 that partitions the pin hole 129. The oxide film is preferably formed over the entire inner circumferential surface 126C. Inner circumferential surface 126C is an example of another inner circumferential surface. Inner circumferential surface 126C is connected to inner circumferential surface 126A and outer circumferential surface 126B. Inner circumferential surface 126C is a surface that extends radially from the fixed boss 116. 【0027】 As shown in Figure 4, the movable sheave 122 is formed in a disc shape. The movable sheave 122 has a movable sheave surface 122S that contacts the V-belt 130. The movable sheave surface 122S is inclined outward (to the left in this case) as it goes from the radially inward to the radially outward. The movable sheave surface 122S is positioned opposite the fixed sheave surface 121S. The V-belt 130 is sandwiched between the movable sheave surface 122S and the fixed sheave surface 121S. The movable boss 127 is connected to the movable sheave 122. The movable boss 127 is fixed to the movable sheave 122, for example, by welding. The movable boss 127 is located in the central part of the movable sheave 122. The movable boss 127 is fixed to the inner circumferential surface of the through-hole portion of the movable sheave 122 by welding or the like. The movable boss 127 protrudes to the left from the movable sheave 122. The movable boss 127 is formed in a cylindrical shape. The movable boss 127 is fitted onto the fixed boss 126 and slides along the outer circumferential surface 126B of the fixed boss 126. The inner circumferential surface 127A of the movable boss 127 has an oxide film similar to the oxide film formed on the inner circumferential surface 116A of the fixed boss 116. The phase difference between the fixed sheave 121 and the movable sheave 122 is determined by attaching a guide pin 128 and a guide roller 128G to a pin hole 129 formed in the fixed boss 126 of the fixed sheave 121 and a torque cam groove 118 formed in the movable boss 127 of the movable sheave 122. 【0028】 As shown in Figure 6, at low speeds, for example, the movable sheave 122 is closest to the fixed sheave 121. At this time, the guide pin 128 is located at the leftmost position of the torque cam groove 118. Then, as the movable sheave 122 moves to the left along the torque cam groove 118, the reduction ratio of the CVT 100 is changed. As shown in Figure 7, at high speeds, for example, the movable sheave 122 is furthest from the fixed sheave 121. At this time, the guide pin 128 is located at the rightmost position of the torque cam groove 118. Then, as the movable sheave 122 moves to the right along the torque cam groove 118, the reduction ratio of the CVT 100 is changed. Furthermore, when the movable sheave 122 moves axially along the torque cam groove 118 in the main shaft 72, an external force is applied to the inner circumferential surface 126C that partitions the pin hole 129 into which the guide pin 128 is inserted. As a result, the inner circumferential surface 126C is prone to wear. However, as described above, an oxide film is formed on the inner circumferential surface 126C, which provides high wear resistance and suppresses wear of the inner circumferential surface 126C. This prevents the guide pin 128 from tilting relative to the pin hole 129. 【0029】 As shown in Figure 2, the transmission case 70 is located to the left of the crankcase 61. The transmission case 70 comprises a case body 80 fixed to the crankcase 61 and a cover 82 detachably fixed to the case body 80. The case body 80 houses the CVT 100. Specifically, the case body 80 houses the drive pulley 110, the driven pulley 120, and the V-belt 130. An opening 81 is formed to the left of the drive pulley 110 in the case body 80. The cover 82 covers the opening 81 in the case body 80. 【0030】 As described above, in the drive pulley 110 of this embodiment, an oxide film is formed on the inner circumferential surface 116A of the fixed boss 116 into which the crankshaft 68 is inserted. Therefore, the sliding properties and wear resistance of the inner circumferential surface 116A of the fixed boss 116 are relatively high. As a result, even if force is applied to the crankshaft 68, for example, and the inner circumferential surface 116A of the fixed boss 116 and the crankshaft 68 rub against each other, wear of the inner circumferential surface 116A of the fixed boss 116 can be suppressed. 【0031】 The driven pulley 120 of this embodiment includes a torque cam groove 118 formed through the movable boss 127 and guiding the movement of the movable sheave 122, a guide pin 128 inserted into the torque cam groove 118, and a pin hole 129 formed in the fixed boss 126 and to which the guide pin 128 is fixed, and an oxide film is formed on the inner circumferential surface 126C of the fixed boss 126 that partitions the pin hole 129. According to the above embodiment, when the movable sheave 122 moves along the torque cam groove 118, an external force from the movable sheave 122 is applied to the guide pin 128 inserted into the torque cam groove 118, so the inner circumferential surface 126C of the fixed boss 126 that partitions the pin hole 129 and the guide pin 128 may rub against each other. Here, an oxide film is formed on the inner circumferential surface 126C, and since the sliding properties and wear resistance of the inner circumferential surface 126C are relatively high, wear of the inner circumferential surface 126C can be suppressed. 【0032】 In the driven pulley 120 of this embodiment, an oxide film is formed on the outer circumferential surface 126B of the fixed boss 126. According to the above embodiment, the sliding properties and wear resistance of the outer circumferential surface 126B of the fixed boss 126 are relatively high due to the presence of the oxide film. As a result, wear of the outer circumferential surface 126B of the fixed boss 126 can be suppressed when the movable sheave 122 slides against the fixed sheave 121. 【0033】 In the driven pulley 120 of this embodiment, an oxide film is formed on the inner circumferential surface 127A of the movable boss 127. According to the above embodiment, the sliding properties and wear resistance of the inner circumferential surface 127A of the movable boss 127 are relatively high due to the presence of the oxide film. As a result, wear on the outer circumferential surface 126B of the fixed boss 126 and the inner circumferential surface 127A of the movable boss 127 can be suppressed when the movable sheave 122 slides against the fixed sheave 121. 【0034】 In the drive pulley 110 and driven pulley 120 of this embodiment, the oxide film contains triiron tetroxide (Fe3O4). The oxide film containing triiron tetroxide has excellent wear resistance and sliding properties, and can be formed relatively inexpensively, thus enabling cost reduction. 【0035】 Preferred embodiments of the present invention have been described above. However, the embodiments described above are merely illustrative, and the present invention can be implemented in various other forms. 【0036】 In the embodiments described above, an oxide film was formed on the inner circumferential surface 116A of the fixed boss 116, but this is not limited to that. Instead of forming an oxide film, the wear resistance and sliding properties of the inner circumferential surface 116A of the fixed boss 116 may be improved by applying a known surface treatment to the inner circumferential surface 116A of the fixed boss 116. 【0037】 In the embodiment described above, a guide roller 128G was attached to the guide pin 128, but the guide roller 128G does not have to be attached to the guide pin 128. In this case, the guide pin 128 inserted into the torque cam groove 118 slides directly against the movable boss 127. [Explanation of symbols] 【0038】 10 Motorcycles 68 Crankshaft 72 Main axis 100 CVT (Belt-type continuously variable transmission) 110 Drive pulley 111 Fixed Sheave 111S Fixed sheave surface 112 Movable Sheave 112S Movable sheave surface 116 Fixed Bosses 116A Inner surface 116B Outer surface 117 Movable Boss 118 Torque cam groove 120 Driven pulley 121 Fixed Sheave 121S Fixed sheave surface 122 Movable Sheave 122S Movable sheave surface 126 Fixed Bosses 126A Inner surface 126B Outer surface 126C Inner surface (other inner surfaces) 127 Movable Boss 127A Inner surface 128 Guide pins 129 pin holes 130 V-belt (drive belt)

Claims

[Claim 1] A pulley used in a belt-type continuously variable transmission, The aforementioned pulley is, A fixed sheave having a fixed sheave surface that contacts the drive belt, A fixed boss extending from the fixed sheave in a first direction and formed in a cylindrical shape, A movable sheave having a movable sheave surface positioned in contact with the drive belt and facing the fixed sheave surface, and capable of approaching and moving away from the fixed sheave, The movable sheave comprises a movable boss that extends in the first direction from the movable sheave, is formed in a cylindrical shape, and is fitted onto the fixed boss and slides along the outer circumferential surface of the fixed boss, A shaft is inserted into the aforementioned fixed boss. An oxide film is formed on the inner circumferential surface of the fixed boss. A pulley in which at least one of Fe3N and Fe4N is present between the inner circumferential surface of the fixed boss and the oxide film. [Claim 2] A torque cam groove is formed through the movable boss and guides the movement of the movable sheave, A guide pin inserted into the torque cam groove, The fixed boss comprises a pin hole formed therein, the guide pin being fixed therein, The pulley according to claim 1, wherein the oxide film is formed on the other inner circumferential surface of the fixed boss that partitions the pin hole. [Claim 3] The pulley according to claim 1 or 2, wherein the oxide film is formed on the outer circumferential surface of the fixed boss. [Claim 4] The pulley according to claim 3, wherein the oxide film is formed on the inner circumferential surface of the movable boss. [Claim 5] The aforementioned oxide film is triiron tetroxide (Fe ３ O ４ The pulley according to claim 1 or 2, including ). [Claim 6] A pulley according to claim 1 or 2, A belt-type continuously variable transmission comprising the drive belt sandwiched between the fixed sheave surface and the movable sheave surface.

Images