CN107869568B

CN107869568B - Belt type continuously variable transmission for vehicle

Info

Publication number: CN107869568B
Application number: CN201710840779.1A
Authority: CN
Inventors: 赤松范一; 原嶋照
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 2016-09-23
Filing date: 2017-09-15
Publication date: 2020-08-11
Anticipated expiration: 2037-09-15
Also published as: JP6493346B2; CN107869568A; JP2018048728A

Abstract

The invention provides a belt type continuously variable transmission for a vehicle. In the belt type continuously variable transmission for a vehicle, the continuously variable transmission relieves the contact surface pressure by forming an R chamfered portion having an R shape at a contact portion of the movable sheave that is in contact with a cylinder block seat in positioning for the movable sheave. The contact surface pressure is reduced to reduce the wear of the positioning portion, so that the fixed sheave and the movable sheave can be arranged at short distances in the axial direction, and the continuously variable transmission can be downsized.

Description

Belt type continuously variable transmission for vehicle

Technical Field

The present invention relates to a continuously variable transmission for a vehicle, which suppresses variation in a transmission gear ratio due to wear of a member that restricts movement of a movable sheave.

Background

As a vehicle transmission, a vehicle continuously variable transmission is known which is configured to include: a fixed sheave integrally formed with the sheave shaft; a main pulley configured by a movable pulley that is capable of moving relative to the pulley shaft in an axial direction thereof; a secondary pulley having the same structure as the primary pulley; a belt wound between the primary pulley and the secondary pulley. In the vehicular continuously variable transmission described in japanese patent application laid-open No. 2008-208861, a cylinder member that constitutes a hydraulic pressure chamber together with the movable sheave comes into contact with the movable sheave when the speed ratio is at a maximum or minimum, and functions as a stopper member that restricts movement of the movable sheave in the axial direction toward the cylinder member.

Disclosure of Invention

When the transmission torque between the primary pulley and the secondary pulley becomes large, a force for bending the pulley shaft provided in each of the fixed pulley and the movable pulley, which are disposed to face each other, outward is generated. Thus, local contact is generated between the movable sheave and the stopper member adjacent thereto, and the pressure at the contact portion, i.e., the contact surface pressure, increases as the transmission torque increases. The increase in the contact surface pressure may cause wear of the stopper member, and the transmission ratio may be changed due to the increase in the wear. On the other hand, from the viewpoint of mountability, it is required to make the vehicular continuously variable transmission as small as possible. In order to achieve such downsizing, a method of reducing the angles of the sheave surfaces of the fixed sheave and the movable sheave and a method of reducing the axial dimension of the movable sheave are effective means. However, in both of these methods, the above-described problem is conspicuous due to an increase in the force of the contact surface between the movable sheave and the stopper member, that is, the contact surface pressure.

The present invention reduces the contact surface pressure between the movable sheave and the stopper member to reduce wear of the stopper member and the movable sheave, thereby suppressing variation in the transmission gear ratio. And the angle of the sheave surface is made smaller than the existing angle by relieving the contact surface pressure of the stopper member with the movable sheave, and the axial dimension of the movable sheave is made shorter than the existing dimension.

A first aspect of the present invention is a belt type continuously variable transmission for a vehicle. The continuously variable transmission includes a pair of variable pulleys and a transmission belt. The pair of variable pulleys includes a fixed pulley and a movable pulley. The fixed pulley is provided integrally with the pulley shaft. The movable sheave is spline-fitted to the pulley shaft so as to be capable of relative movement in the axial direction of the pulley shaft and not capable of relative rotation around the pulley shaft in a state of facing the fixed sheave. The belt is wound around the pair of variable pulleys. The movable sheave includes a cylindrical boss portion protruding toward the stopper member. The stopper member is located on the opposite side of the fixed sheave with respect to the movable sheave. The annular end surface of the boss portion includes an outer peripheral side end surface, an inner peripheral side end surface, and an annular connection surface. The annular end surface faces the stopper member, and the inner peripheral end surface is an end surface that is farther from the stopper member than the outer peripheral end surface. The annular connection surface connects the outer circumferential end surface and the inner circumferential end surface. A chamfered portion is provided on a boundary line between the outer peripheral side end surface and the annular connecting surface.

According to the above configuration, since the chamfered portion is provided at the boundary between the outer peripheral side end surface of the boss portion and the annular connecting surface, the chamfered portion comes into contact with the stopper member, and therefore, the contact surface pressure at the contact portion between the movable sheave and the stopper member can be reduced, and the abrasion of the stopper member and the movable sheave can be suppressed, thereby suppressing the variation in the gear ratio. Further, by reducing the wear of the stopper member and the movable sheave, it is possible to allow a stronger clamping force to be applied to the belt, and it is possible to reduce the angle of the sheave surface as compared with the conventional art, and to shorten the axial dimension of the movable sheave as compared with the conventional art, thereby also achieving a reduction in size of the belt type continuously variable transmission for a vehicle.

In the belt type continuously variable transmission for a vehicle, the spline fitting of the pulley shaft and the movable pulley may be any one of involute spline fitting, rolling spline fitting, and drum shaft spline fitting. According to this configuration, it is possible to ensure good relative movement of the fixed sheave and the movable sheave that are formed integrally with the sheave shaft in the axial direction of the sheave shaft.

In the belt type continuously variable transmission for a vehicle, the chamfered portion may be provided in a range on an inner diameter side of a half or less of a difference between an outer diameter and an inner diameter of the annular end surface. According to this structure, even if a force that expands the movable sheave and the fixed sheave in parallel with the axial direction of the sheave shaft is generated due to an increase in transmission torque, the contact surface of the sleeve end portion that contacts the adjacent stopper member is sufficiently ensured by forming the R chamfered portion so as to be confined within a predetermined portion. By ensuring a large contact surface, the average surface pressure from the sleeve end toward the stopper member is suppressed. This suppresses wear of the stopper member and the movable sheave, and also suppresses variation in the transmission gear ratio. Further, by reducing the wear of the stopper member and the movable sheave, the angle of the sheave surface can be reduced as compared with the conventional art, and the axial dimension of the movable sheave can be shortened as compared with the conventional art, whereby the belt type continuously variable transmission for a vehicle can be also downsized.

Drawings

Features, advantages and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals refer to like elements, and wherein:

fig. 1 is a diagram illustrating a schematic configuration of a power transmission path from an engine to drive wheels constituting a vehicle to which the present invention is applied.

Fig. 2 is a diagram illustrating switching of the running mode of the power transmission device in the vehicle of fig. 1.

Fig. 3 is a sectional view illustrating the structures of a pair of movable pulleys and fixed pulleys and peripheral components in the belt type continuously variable transmission of fig. 1.

Fig. 4 is an enlarged sectional view illustrating the movable sheave and the sheave shaft of fig. 3.

Fig. 5 is a cross-sectional view showing an example of a deformation mode of the pair of movable and fixed sheaves and the peripheral members of fig. 3.

Fig. 6 is a sectional view showing a detailed structure of the movable sheave having the R chamfered portion at the end of the sleeve to which the present invention is applied, by further enlarging fig. 4.

Fig. 7 is a pressure distribution diagram showing contact surface pressures generated at respective contact surfaces on a sleeve end portion having an R chamfer and a sleeve end portion not having an R chamfer on the basis of relative positions with respect to an opposed pulley.

Fig. 8 is a cross-sectional view of the movable sheave and the sheave shaft of fig. 3 in a case where a rolling spline is used for spline fitting.

Fig. 9 is a view of the sleeve end portion in a region where the R-chamfered portion is formed, as viewed from the axial direction.

Fig. 10 is a sectional view showing a detailed structure of a sleeve end portion and a spline end portion of a movable sheave in a conventional structure.

Detailed Description

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

Fig. 1 is a diagram illustrating a schematic configuration of a vehicle 10 to which the present invention is applied. In fig. 1, a vehicle 10 includes: an engine 12 such as a gasoline engine or a diesel engine that functions as a driving source for running, drive wheels 14, and a power transmission device 16 provided between the engine 12 and the drive wheels 14. The power transmission device 16 includes, in a casing 18 as a non-rotating member: a torque converter 20 as a fluid type transmission device coupled to the engine 12, an input shaft 22 coupled to the torque converter 20, a belt type continuously variable transmission 24 (hereinafter referred to as a continuously variable transmission) coupled to the input shaft 22, a forward/reverse switching device 26 similarly coupled to the input shaft 22, a gear transmission mechanism 28 as a gear transmission portion coupled to the input shaft 22 via the forward/reverse switching device 26 and provided in parallel with the continuously variable transmission 24, the output shaft 30 and the counter shaft 32, which are common output rotary members of the continuously variable transmission 24 and the gear transmission mechanism 28, a reduction gear device 34 composed of a pair of gears that are provided so as to be incapable of relative rotation with respect to the output shaft 30 and the counter shaft 32 and that mesh with each other, a differential gear 38 connected to a gear 36 that is provided so as to be incapable of relative rotation with respect to the counter shaft 32, a pair of axles 40 coupled to the differential gear 38, and the like. In the power transmission device 16 configured in this manner, the power of the engine 12 (synonymous with torque or force if not particularly distinguished) is transmitted to the pair of drive wheels 14 sequentially via the torque converter 20, the continuously variable transmission 24 or the forward/reverse switching device 26, the gear transmission mechanism 28, the reduction gear device 34, the differential gear 38, the axle 40, and the like. Further, during operation of the engine 12, the output torque of the engine 12 is always input to the input shaft 22.

In this way, the power transmission device 16 includes the gear transmission mechanism 28 as the first transmission unit and the continuously variable transmission 24 as the second transmission unit, which are provided in parallel between the engine 12 (here, the input shaft 22 as the input rotary member for transmitting the power of the engine 12 is also synonymous) and the drive wheels 14 (here, the output shaft 30 as the output rotary member for outputting the power of the engine 12 to the drive wheels 14 is also synonymous). Thus, the power transmission device 16 includes a plurality of power transmission paths PT1, such as a first power transmission path PT1 for transmitting the power of the engine 12 from the input shaft 22 to the drive wheels 14 (i.e., the output shaft 30) via the gear train 28, and a second power transmission path PT2 for transmitting the power of the engine 12 from the input shaft 22 to the drive wheels 14 (i.e., the output shaft 30) via the continuously variable transmission 24, in parallel between the input shaft 22 and the output shaft 30. The power transmission device 16 switches the first power transmission path PT1 and the second power transmission path PT2 according to the running state of the vehicle 10. Therefore, the power transmission device 16 includes a plurality of engagement devices that selectively switch the power transmission path PT through the first power transmission path PT1 and the second power transmission path PT2 to transmit the power of the engine 12 to the drive wheels 14. The engagement device includes a first clutch C1 that connects or disconnects the first power transmission path PT1 and a second clutch C2 that is a second engagement device that connects or disconnects the second power transmission path PT 2.

The torque converter 20 is provided around an input shaft 22 so as to be coaxial with the input shaft 22, and includes a pump impeller 20p coupled to the engine 12 and a turbine runner 20t coupled to the input shaft 22. A mechanical oil pump 42 is connected to the pump impeller 20p, and the oil pump 42 is rotationally driven by the engine 12. Thus, an operating fluid pressure is generated for performing shift control of the continuously variable transmission 24, operating the plurality of engagement devices, or supplying lubricating oil to each component of the power transmission device 16. During operation of the engine 12, the output torque of the engine 12 is always input to the input shaft 22 via the torque converter 20.

The forward/reverse switching device 26 is provided on the first power transmission path PT1 coaxially with the input shaft 22 around the input shaft 22, that is, on the first shaft RC1, and includes a double-pinion planetary gear device 26p, a first clutch C1, and a first brake B1. The planetary gear device 26p is a differential mechanism having three rotation elements, i.e., a carrier 26c as an input element, a sun gear 26s as an output element, and a ring gear 26r as a reaction element. The carrier 26c is integrally coupled to the input shaft 22, the ring gear 26r is selectively coupled to the housing 18 via the first brake B1, the sun gear 26s is coupled to the small-diameter gear 44, and the small-diameter gear 44 is provided around the input shaft 22 so as to be rotatable coaxially with respect to the input shaft 22. The carrier 26C and the sun gear 26s are selectively coupled via a first clutch C1. Thus, the first clutch C1 is an engagement device that selectively couples two of the three rotational elements for forward gear travel, and the first brake B1 is an engagement device that selectively couples the ring gear 26r, which is the reaction force element, to the housing 18 for reverse travel.

The gear transmission mechanism 28 includes a small-diameter gear 44 and a large-diameter gear 48, and the large-diameter gear 48 is provided around the gear mechanism counter shaft 46 so as to be relatively non-rotatable coaxially with respect to the gear mechanism counter shaft 46, and meshes with the small-diameter gear 44. The gear transmission mechanism 28 includes an idler gear 50 provided around the gear mechanism counter shaft 46 so as to be relatively rotatable coaxially with respect to the gear mechanism counter shaft 46, and an output gear 52 provided around the output shaft 30 so as to be relatively non-rotatable coaxially with respect to the output shaft 30 and meshing with the idler gear 50. The output gear 52 is larger in diameter than the idler gear 50. Therefore, the gear transmission mechanism 28 is a gear transmission mechanism in which one speed ratio (gear position) as a predetermined speed ratio (gear position) is formed on the power transmission path PT between the input shaft 22 and the output shaft 30. A meshing clutch D1 for selectively connecting and disconnecting the large diameter gear 48 and the idler gear 50 is further provided around the gear mechanism counter shaft 46. The meshing clutch D1 is provided in the power transmission device 16, is a device that is disposed on the power transmission path between the forward/reverse switching device 26 (the first clutch C1 is also synonymous), and the output shaft 30, functions as a third engagement device that connects or disconnects the first power transmission path PT1, and is included in the plurality of engagement devices. That is, the meshing clutch D1 is provided on the output shaft 30 side of the first clutch C1. The third engagement device is engaged with the first clutch C1 to form a first power transmission path PT 1.

Specifically, the meshing clutch D1 includes: a clutch sleeve 54 provided around the gear mechanism counter shaft 46 so as to be relatively non-rotatable coaxially with respect to the gear mechanism counter shaft 46; a clutch gear 56 disposed between the idler gear 50 and the clutch sleeve 54 and fixed to the idler gear 50; the sleeve 58 is cylindrical and is spline-fitted (engaged) to the clutch sleeve 54 so as to be incapable of relative rotation about the gear mechanism counter shaft 46 and capable of relative movement in a direction parallel to the shaft. The sleeve 58, which rotates integrally with the clutch sleeve 54 at all times, is moved toward the clutch gear 56 and meshed with the clutch gear 56, whereby the idler gear 50 and the gear mechanism counter shaft 46 are connected together. The meshing clutch D1 includes a known synchronizing gear mechanism S1 that synchronizes rotation when the sleeve 58 and the clutch gear 56 are engaged with each other. In the intermesh clutch D1 configured in this manner, the fork shaft 60 is operated by the hydraulic actuator 62. Thus, the sleeve 58 is slid in a direction parallel to the axis of the gear mechanism counter shaft 46 by the shift fork 64 fixed to the fork shaft 60, and is switched between the engaged state and the released state.

The first power transmission path PT1 is formed by engaging the intermesh clutch D1 with the first clutch C1 (or the first brake B1) provided on the input shaft 22 side of the intermesh clutch D1. In the power transmission device 16, when the first power transmission path PT1 is formed, the power of the engine 12 can be transmitted from the input shaft 22 to the output shaft 30 via the gear transmission mechanism 28, and the power transmission state is enabled. On the other hand, the first power transmission path PT1 is set to a neutral state (power transmission cut-off state) in which the power transmission is cut off when at least the first clutch C1 and the first brake B1 are released together or at least the intermesh clutch D1 is released.

The continuously variable transmission 24 includes: a primary pulley (primary pulley) 66 that is provided on the input shaft 22 that rotates together with the engine 12, and whose effective diameter is variable; a sub-pulley (sub-pulley) 70 that is provided on the rotating shaft 68 coaxial with the output shaft 30 and has a variable effective diameter; and a belt 72 wound between the

pulleys

66 and 70. Therefore, even when the vehicle is stopped during operation of the engine 12 in which the torque converter 20 couples the continuously variable transmission 24 to the engine and the second clutch C2 is released, the continuously variable transmission 24 transmits power to the output shaft 30 by frictional force (belt clamping force) between the

pulleys

66 and 70 and the transmission belt 72. The main sheave 66 is subjected to pressure regulation control of a sheave hydraulic pressure supplied to the main sheave 66 (i.e., a line pressure Pin supplied to the hydraulic cylinder 66 c) by a hydraulic control circuit (not shown), thereby applying a main thrust Win (equal to the line pressure Pin × a pressure receiving area) that changes the V-groove width between the fixed sheave 66a and the movable sheave 66 b. The sub sheave 70 is subjected to pressure regulation control of the sheave hydraulic pressure supplied to the sub sheave 70 (i.e., the sub pressure Pout supplied to the secondary side hydraulic cylinder 70 c) by the hydraulic pressure control circuit, thereby applying a sub thrust Wout (the sub pressure Pout × the pressure receiving area) that changes the V groove width between the fixed sheave 70a and the movable sheave 70 b. In the continuously variable transmission 24, the main thrust force Win (main pressure Pin) and the sub thrust force Wout (sub pressure Pout) are controlled, respectively, so that the V groove width of each of the

pulleys

66, 70 is changed and the winding diameter (effective diameter) of the transmission belt 72 is changed. Therefore, the speed change ratio γ cvt (primary pulley rotation speed Npri/secondary pulley rotation speed Nsec) is changed and the frictional force between the

pulleys

66, 70 and the transmission belt 72 is controlled so that the transmission belt 72 does not slip.

The output shaft 30 is disposed around the rotation shaft 68 so as to be rotatable relative to the rotation shaft 68 coaxially therewith. The second clutch C2 is provided on the drive wheel 14 (synonymous with the output shaft 30 herein) side (i.e., between the secondary pulley 70 and the output shaft 30) with respect to the continuously variable transmission 24, and selectively connects or disconnects the secondary pulley 70 (the rotary shaft 68) and the output shaft 30. The second power transmission path PT2 is formed by the second clutch C2 being engaged. When the second power transmission path PT2 is formed in the power transmission device 16, the power of the engine 12 can be transmitted from the input shaft 22 to the output shaft 30 via the continuously variable transmission 24. On the other hand, the second power transmission path PT2 is set to the neutral state when the second clutch C2 is released.

Fig. 2 is a diagram for explaining switching of the running mode by using an engagement table of an engagement device for each running mode (running model) of the power transmission device 16. In fig. 2, C1 corresponds to the operating state of the first clutch C1, C2 corresponds to the operating state of the second clutch C2, B1 corresponds to the operating state of the first brake B1, D1 corresponds to the operating state of the meshing clutch D1, "o" indicates engagement (connection), "x" indicates release (cut).

In fig. 2, in a running mode in which the power of the engine 12 is transmitted to the output shaft 30 via the gear train 28 (i.e., a running mode in which the first power transmission path PT1 through the gear train 28 is utilized), that is, a gear running mode, the first clutch C1 and the meshing clutch D1 are engaged and the second clutch C2 and the first brake B1 are released. In the gear running mode, forward running is possible. When the first brake B1 and the meshing clutch D1 are engaged and the second clutch C2 and the first clutch C1 are released, reverse travel is possible.

In a running mode in which the power of the engine 12 is transmitted to the output shaft 30 by the Continuously Variable Transmission 24 (i.e., a running mode in which the power is transmitted through the second power Transmission path PT2 via the Continuously Variable Transmission 24), that is, a Continuously Variable Transmission (hereinafter, referred to as a CVT running mode), the second clutch C2 is engaged and the first clutch C1 and the first brake B1 are released. In the CVT running mode, forward running is possible. In the CVT running mode, the meshing clutch D1 is engaged in the CVT running (medium vehicle speed) mode, while the meshing clutch D1 is released in the CVT running (high vehicle speed) mode. The meshing clutch D1 functions as a driven input cutoff clutch that cuts off input from the drive wheels 14.

The gear running mode is selected in a low vehicle speed region including, for example, when the vehicle is stopped. In the power transmission device 16, the speed ratio γ gear (also referred to as speed ratio EL) formed by the first power transmission path PT1 passing through the gear train 28 is set to a value (i.e., a speed ratio on the low speed side) greater than the maximum speed ratio (i.e., the lowest speed ratio which is the speed ratio on the lowest vehicle speed side) γ max that can be formed by the second power transmission path PT2 passing through the continuously variable transmission 24. That is, the second power transmission path PT2 has the speed ratio γ cvt on the higher vehicle speed side (high speed side) than the speed ratio EL formed by the first power transmission path PT 1. For example, the speed ratio EL corresponds to a first speed ratio γ 1, which is a speed ratio γ of a first speed gear stage in the power transmission device 16, and the lowest speed ratio γ max of the continuously variable transmission 24 corresponds to a second speed ratio γ 2, which is a speed ratio γ of a second speed gear stage in the power transmission device 16. Therefore, the gear running mode and the CVT running mode are switched according to, for example, a shift line for switching the first-speed shift stage and the second-speed shift stage in the shift map of the stepped transmission. In the CVT running mode, for example, a shift is performed in which the speed ratio γ CVT is changed based on the running state such as the accelerator opening degree or the vehicle speed.

Fig. 3 is a sectional view of the main pulley 66 of the continuously variable transmission 24 of fig. 1. The main sheave 66 includes: a disk-shaped fixed pulley 66a integrally formed with a pulley shaft 78 rotatably supported by the housing 18 via a bearing 74 and a bearing 76; a movable sheave 66b provided so as to form a V-shaped first sheave groove 80 with the fixed sheave 66a, and relatively movable in the axial direction while being relatively non-rotatable with respect to the sheave shaft 78; and a hydraulic cylinder 66c that moves the movable sheave 66b in the axial direction in accordance with the supplied hydraulic pressure, and changes the groove width of the first sheave groove 80 by moving the fixed sheave 66a and the movable sheave 66b closer to or farther from each other in the axial direction. The pulley shaft 78 is supported by the first shaft RC1 so as to be rotatable about the first shaft RC1 by the bearing 74 and the bearing 76, both ends of the outer periphery of which are fitted in the housing 18. A groove having an involute curve on a side surface is formed on the inner diameter of the movable sheave 66 b. Further, the movable sheave 66b and the pulley shaft 78 are relatively movable without relative rotation by involute spline fitting (hereinafter, spline fitting) using a groove formed in the movable sheave 66b and a groove formed in the outer diameter of the pulley shaft 78.

The fixed sheave 66a of the main sheave 66 is a disk-shaped member that radially protrudes from the outer peripheral surface of the sheave shaft 78. The fixed sheave 66a is formed with a conical tapered surface 82 formed in a direction away from the movable sheave 66b as the diameter of the tapered surface increases.

The movable sheave 66b of the main sheave 66 is constituted by: a boss portion 88 spline-fitted to an inner peripheral portion thereof so as to be movable relative to the pulley shaft 78 in the axial direction and not to be rotatable relative to the pulley shaft about the first axis RC 1; a disk portion 90 that protrudes radially from the end portion on the fixed sheave 66a side in the axial direction of the boss portion 88; and an outer peripheral tube portion 92 extending in parallel with the first shaft RC1 in the axial direction from the outer peripheral portion of the disc portion 90 toward a direction away from the fixed sheave 66 a. The disk portion 90 is formed with a conical tapered surface 94 formed in a direction away from the fixed sheave 66a as the diameter of the disk portion increases. The first pulley groove 80 is formed by the tapered surface 94 formed on the movable pulley 66b and the tapered surface 82 formed on the fixed pulley 66 a.

The hydraulic cylinder 66c includes a bottomed cylindrical cylinder member 96 disposed on the back side of the tapered surface 94 in the axial direction of the movable sheave 66 b. The cylinder member 96 is fixed so as not to be movable in the axial direction by a nut 98 being coupled thereto in a state where the inner peripheral portion thereof is held in the axial direction between the step portion of the pulley shaft 78 and the bearing 76 by a disc-shaped cylinder block 100 functioning as a stopper. The movable sheave 66b is in contact with a cylinder block 100 as an abutment target member provided in a fixed position in the direction of the first axis RC1, and thereby forms a speed ratio on the lowest vehicle speed side where the distance between the movable sheave 66b and the fixed sheave 66a is maximized and the speed ratio γ cvt is the lowest. The cylinder member 96 has a curved shape, and a cylindrical portion concentric with the first shaft RC1 is formed on the outer peripheral side of the cylinder member 96. The inner peripheral surface of the cylindrical portion and the outer peripheral end portion of the outer peripheral cylindrical portion 92 of the movable sheave 66b are configured to be slidable via an oil seal. Thereby, a liquid-tight hydraulic chamber 97 (97 is not shown) is formed between the cylinder member 96 and the movable sheave 66 b. The hydraulic pressure chamber 97 is supplied with hydraulic pressure from a hydraulic pressure control circuit, not shown, via a hydraulic passage formed in the pulley shaft 78 or a hydraulic passage formed in the movable pulley 66 b.

Fig. 4 is an enlarged view of a portion surrounded by an oval broken line in fig. 3, that is, the boss portion 88 and the cylinder block 100 of the movable pulley 66b and a portion a serving as a peripheral portion thereof. An inner peripheral spline tooth is formed on the inner diameter side of the cylindrical boss portion 88, the boss portion 88 has a boss portion inner peripheral surface 88i passing through the top of the inner peripheral spline tooth, and a boss portion outer peripheral surface 88o formed of a fixed outer diameter on the cylinder block 100 side.

Fig. 5 is a diagram showing a deformation pattern exaggerated to facilitate understanding of an example of a deformation pattern generated when the transmission torque transmitted from the primary pulley 66 to the secondary pulley 70 is increased. Fig. 5 shows the main pulley 66, in which the opening of the first pulley groove 80 on the upper side of the first shaft RC1 is larger than the normal position, and the opening of the first pulley groove 80 on the lower side of the first shaft RC1 is smaller than the normal position. At the same time, the first axis RC1 shows a bend toward the upper side of fig. 5.

Fig. 10 is a view showing an end face of the conventional art, and is an enlarged view B1 including a portion where the boss portion 88 contacts the cylinder block 100 and a boss portion inner peripheral surface 88i of the boss portion 88. In enlarged view B1, an end surface 102 facing the cylinder block 100 of the boss portion 88 has: an annular inner peripheral end surface 108 that is C-chamfered on the inner diameter side, an annular outer peripheral end surface 104 that is formed radially outward and axially outward from the inner peripheral end surface 108 and that contacts the cylinder block 100, and an annular connecting surface 106 that connects the inner peripheral end surface 108 and the outer peripheral end surface 104. Further, the inner periphery side end surface 108 and the annular connection surface 106 are connected by, for example, an R shape (other paragraph is modified for an R chamfered portion) or a gentle curve formed with a predetermined radius of curvature R1.

As shown in an enlarged view B1 of fig. 10, a boundary between the outer peripheral end surface 104 and the annular connection surface 106 forms a ridge line formed by straight line connection in cross section, and the inner peripheral edge of the outer peripheral end surface 104 is in contact with the cylinder block 100. Therefore, when the fixed sheave 66a and the movable sheave 66b are deformed as shown in fig. 5, that is, the first sheave groove 80 is wider than the normal position as the distance from the secondary sheave 70 increases, for example, due to a large transmission torque transmitted from the main sheave 66 to the secondary sheave 70, the ridge line between the outer peripheral side end face 104 and the annular connecting face 106 locally contacts the cylinder block 100 at the end face of the related art in fig. 10, and a large contact face pressure (MPa) is generated at the contact portion.

The enlarged view B2 of fig. 6 of the present embodiment differs from the enlarged view B1 of fig. 10 in that an R chamfered portion 110 formed with a curvature substantially equal to R2 is provided between the outer peripheral side end face 104 and the annular connecting surface 106, and the enlarged view B2 has the same sectional shape as the enlarged view B1 except for the R chamfered portion 110. When the fixed sheave 66a and the movable sheave 66B are deformed as shown in fig. 5 due to a large transmission torque transmitted from the main sheave 66 to the sub sheave 70 or the like, the R chamfered portion 110, which is the boundary between the outer peripheral end surface 104 and the annular connecting surface 106 in fig. 6, has a predetermined radius of curvature R2, so that the area of the contact portion with the cylinder block 100 is enlarged as compared with the cross-sectional shape of the enlarged view B1, and the contact surface pressure is reduced. By reducing the contact surface pressure, wear of the outer peripheral end surface 104 of the cylinder block 100 and the movable sheave 66b that are in contact with each other can be reduced, and variation in the transmission gear ratio γ cvt can be reduced. Further, the R-chamfered portion 110 has a predetermined radius of curvature R2, but is not particularly limited thereto, and may be formed of a curve or a polygon having a plurality of surfaces, which can reduce the contact surface pressure of the outer peripheral end surface 104 with the cylinder block 100 when the deformation shown in fig. 5 occurs in the fixed sheave 66a and the movable sheave 66 b.

Fig. 7 is a graph comparing contact surface pressures in a case where the R-chamfered portion 110 is not present at the boundary between the outer peripheral end surface 104 and the annular connection surface 106 (referred to as "no R" in fig. 7) and a case where the R-chamfered portion 110 is present at the boundary between the outer peripheral end surface 104 and the annular connection surface 106 (referred to as "additional R" in fig. 7). The phase (deg) shown as the horizontal axis represents the rotation angle (rotation phase) of the main sheave 66, and the angles farthest from the sub sheaves 70 forming a pair with the main sheave 66 are set to 0 ° and 360 °, and the angle closest to the sub sheaves 70 is set to 180 °, and an example of the distribution of the contact surface pressure in the circumferential direction applied from the outer peripheral end surface 104 to the cylinder block 100 is shown. The contact surface pressure is a value measured by a surface pressure sensor, and is measured under the condition that the same force is applied to the main pulley 66 through the transmission belt 72. In the contact surface pressure under the measurement conditions, when the R chamfered portion 110 is not provided at the boundary between the outer peripheral side end surface 104 and the annular connection surface 106, the value is about 1.6 times to 1.8 times as large as that in the case where the R chamfered portion 110 is provided, so that the wear of the outer peripheral side end surface 104 of the cylinder block 100 and the movable sheave 66b which are in contact with each other can be reduced by providing the R chamfered portion 110, and the variation in the transmission ratio γ cvt can be suppressed. Further, of the contact surface pressures in the radial direction, the maximum contact surface pressure of 0 ° or 360 °, that is, the contact surface pressure at the position farthest from the secondary pulley 70 forming a pair with the primary pulley 66 is about 3.8 times to 4.1 times as large as the contact surface pressure at the position 180 °, that is, the position closest to the secondary pulley 70, and therefore, the cylinder block 100 and the outer peripheral side end surface 104 of the movable pulley 66b, which are in contact with each other at the position farthest from the secondary pulley 70, are worn more greatly.

According to the present embodiment, the axially outer end portion of the movable sheave 66b that is relatively movable in the axial direction of the sheave shaft 78 of the continuously variable transmission 24 includes an inner peripheral end surface 108 that is chamfered on the inner diameter side, an outer peripheral end surface 104 that is formed radially outward and radially outward from the inner peripheral end surface 108, an annular connection surface 106 that connects the inner peripheral end surface 108 and the outer peripheral end surface 104, and an R chamfered portion 110 that forms the inner peripheral edge of the outer peripheral end surface 104 into an R shape. Even when the transmission torque transmitted from the primary pulley 66 to the secondary pulley 70 is large and the deformation that expands the first pulley groove 80 compared to the normal position is formed in the fixed pulley 66a and the movable pulley 66b as the distance from the secondary pulley 70 increases, the R-chamfered portion 110 formed in an R shape is formed on the inner peripheral edge of the outer peripheral side end surface 104, so that the contact surface pressure applied from the outer peripheral side end surface 104 to the cylinder block 100 is reduced, and the wear of the outer peripheral side end surface 104 and the cylinder block 100 is suppressed, thereby suppressing the variation of the speed ratio γ cvt. Further, by reducing the wear, a stronger clamping force applied to the belt is allowed, and the angle of the tapered surfaces 82, 94 of the fixed sheave 66a and the fixed sheave 66b can be made smaller and the axial dimension of the movable sheave 66b can be made shorter than in the related art, thereby enabling downsizing of the continuously variable transmission 24.

Next, another embodiment of the present invention will be explained. In the following description, the same reference numerals are given to the same portions as those of the above-described embodiment, and the description thereof is omitted.

Fig. 8 is a sectional view illustrating only the main sheave 66 on the upper side of the first shaft RC1 as a rotation shaft. In the main pulley 66 shown in fig. 3, the pulley shaft 78 and the movable pulley 66b are spline-fitted (engaged) by grooves having involute curves, that is, by involute splines. On the other hand, in fig. 8, half-moon-shaped grooves are formed in the pulley shaft 78 and the movable pulley 66b, and a plurality of balls made of steel balls are sealed in the grooves, so that torque transmission is performed in the radial direction and spline fitting, that is, rolling spline fitting is performed by rolling splines having high sliding ability in the axial direction. In addition, instead of the plurality of balls, a sleeve-shaped roller may be slid in the axial direction of the sleeve inside the groove to perform spline fitting, that is, barrel shaft spline fitting. In this way, the fixed sheave 66a and the movable sheave 66b formed integrally with the sheave shaft 78 can be prevented from rotating relative to each other about the first shaft RC1, and can be moved relatively in the axial direction of the sheave shaft 78.

Further, other embodiments of the present invention will be explained. In the following description, the same reference numerals are given to the same portions as those of the above-described embodiment, and the description thereof is omitted.

Fig. 9 is a view of the boss portion 88 as viewed from the cylinder block 100 side, and a range in which the R-chamfered portion 110 is formed is set in the outer peripheral side end surface 104. The center value of the outer diameter of the outer peripheral end surface 104, which is the boss portion outer peripheral surface 88o, and the inner diameter of the inner peripheral end surface 108, which is the boss portion inner peripheral surface 88i, is set to the center line 88c, and the R-chamfered portion 110 is formed only in the range between the center line 88c and the boss portion inner peripheral surface 88i, that is, in the region on the inner diameter side of the half or less of the difference between the outer diameter and the inner diameter of the annular end surface 102 of the boss portion 88. In this way, even if a force that expands the fixed sheave 66a and the movable sheave 66b in the direction parallel to the first shaft RC1 is generated due to an increase in transmission torque, the contact area between the cylinder block 100 and the outer peripheral side end surface 104 is reliably ensured because the R-chamfered portion 110 is formed so as to be limited to a predetermined range. This reduces the average surface pressure at the contact portion, thereby suppressing wear due to contact between the cylinder block 100 and the outer peripheral end surface 104, and also reducing variation in the transmission ratio by suppressing wear. Further, by suppressing wear due to contact between the cylinder block 100 and the outer peripheral side end surface 104, the angle of the tapered surfaces 82 and 94 can be made smaller than in the related art, and the axial dimension of the movable sheave 66b can be made smaller than in the related art, whereby the continuously variable transmission 24 can also be made smaller in size.

Although the embodiments of the present invention have been described in detail above with reference to the drawings, the present invention can be applied to other embodiments.

For example, although the foregoing embodiment is configured to provide the R chamfered portion 110 on the outer peripheral side end face 104 of the movable sheave 66b of the main sheave 66, the R chamfered portion 110 may be provided on the outer peripheral side end face 104 of the movable sheave 70b of the secondary sheave 70 without being limited to the main sheave 66, and thus the same effect as that of the main sheave 66 can be expected to be produced also on the secondary sheave 70.

Although the above-described embodiments 2 and 3 have been described using the main pulley 66, the present invention is not particularly limited to the main pulley 66, and can be applied to the sub-pulley 70.

In the above-described embodiment, the cylinder block 100 is in contact with the outer peripheral side end surface 104 and functions as a stopper member, but the stopper member is not particularly limited to the cylinder block 100, and members that function as a position fixing member in the direction of the first axis RC1, for example, the

hydraulic cylinders

66c and 70c, and the like may be used.

The continuously variable transmission 24 of the embodiment is a device that transmits power via the transmission belt 72, but is not limited to a transmission belt, and is not particularly limited as long as it can be wound around each pulley, such as a chain.

In the above-described embodiment, the fixed pulley 66a is formed integrally with the pulley shaft 78, but it is not particularly necessary to form it integrally, and it may be formed integrally by a mechanical method as long as rigidity can be ensured.

The above-described embodiment is merely one embodiment, and the present invention can be implemented in various modifications and improvements based on the knowledge of those skilled in the art.

Claims

1. A belt type continuously variable transmission for a vehicle, characterized by comprising a pair of variable pulleys and a transmission belt wound around the pair of variable pulleys, wherein,

the pair of variable pulleys includes a fixed pulley and a movable pulley,

the fixed pulley is provided integrally with the pulley shaft,

the movable sheave is spline-fitted to the pulley shaft so as to be capable of relative movement in an axial direction of the pulley shaft and not capable of relative rotation around the pulley shaft in a state of facing the fixed sheave,

the movable sheave includes a cylindrical boss portion projecting toward the stopper member,

the stopper member is located on the opposite side of the fixed sheave with respect to the movable sheave,

the annular end surface of the boss portion includes an annular outer peripheral side end surface, an annular inner peripheral side end surface, and an annular connecting surface,

the annular end surface is opposed to the stopper member,

the annular inner peripheral side end surface is an end surface that is farther from the stopper member than the outer peripheral side end surface in the rotation center line direction,

the annular connecting surface connects an inner peripheral edge of the annular outer peripheral side end surface and an outer peripheral edge of the annular inner peripheral side end surface by a tapered surface that is more inclined toward an inner peripheral side as it goes toward the fixed sheave,

a chamfered portion is provided on a boundary line between the outer peripheral side end surface and the annular connecting surface.

2. The belt-type continuously variable transmission for a vehicle according to claim 1,

the spline fitting of the pulley shaft and the movable pulley is one of involute spline fitting, rolling spline fitting and drum shaft spline fitting.

3. The belt-type continuously variable transmission for a vehicle according to claim 1 or claim 2,

the chamfered portion is provided in a range on the inner diameter side of the annular end surface where the difference between the outer diameter and the inner diameter is not more than half of the difference.