JP2018168858A - Continuously variable transmission - Google Patents

Abstract

To suppress vibration of a continuously variable transmission, to reduce vibration noise occurring from the continuously variable transmission.SOLUTION: A continuously variable transmission has a movable sheave 23, and the movable sheave 23 has a hollow shaft part 23a and a movable sheave body part 23b. At an axial center part of the hollow shaft part 23a, provided is an engagement part 51 engaging to a rotational shaft so as to freely slide in an axis direction. At a base end part of the hollow shaft part 23a, provided is a base end side fitting part 52 fitted to an outer peripheral surface of the rotational shaft in a slidable manner. At a tip part of the hollow shaft part 23a, provided is a tip side fitting part 53 fitted to the outer peripheral surface of the rotational shaft in a slidable manner. A position of an anti-node of axial vibration on a secondary shaft 12, or the rotational shaft, is arranged at an axial center part of the tip side fitting part 53.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a continuously variable transmission having a primary pulley, a secondary pulley, and a power transmission element such as a chain wound around them.

  A continuously variable transmission for a vehicle has a variable-width primary pulley provided on an input-side primary shaft and a variable-width secondary pulley provided on an output-side secondary shaft, and these pulleys A power transmission element such as a chain is wound around the frame. The primary pulley has a fixed sheave provided integrally with the primary shaft, and a movable sheave that is slidably mounted in the axial direction on the primary shaft and rotates integrally with the primary shaft, and is disposed between the fixed sheave and the movable sheave. A power transmission element is wound around the groove. The secondary pulley has a fixed sheave integrally provided on the secondary shaft and a movable sheave that is slidably mounted on the secondary shaft in the axial direction and rotates integrally, and is formed between the fixed sheave and the movable sheave. A power transmission element is wound around the groove.

  Patent Documents 1 and 2 describe a continuously variable transmission in which a chain is used as a power transmission element.

JP 2009-144751 A JP 2011-112112 A

  In the continuously variable transmission described in Patent Document 1, the movable sheave and the fixed sheave each include a pulley body and a power transmission surface forming member fixed thereto in order to improve the shift response and suppress the generation of noise. And the rigidity of the pulley body is higher than the rigidity of the power transmission surface forming member. In the chain type continuously variable transmission described in Patent Document 2, the center position between the fixed sheave of the primary pulley and the sheave surface of the movable sheave and the fixing of the secondary pulley are reduced in order to reduce the chain jar noise generated during deceleration. The axial distance between the sheave and the center position between the sheave surfaces of the movable sheave is misaligned. Thus, the secondary shaft is supported so as to be movable in the axial direction within a predetermined range in accordance with the thrust load applied to the output gear from the differential device.

  In a continuously variable transmission having a chain as a power transmission element, chain noise is generated when the vehicle travels because the distance between the pitches of the chain is large. As a result of various experimental results to suppress the occurrence of chain noise, if the vibration force of the chain and the bending mode unique to the pulley overlap, the vibration in the bearing increases and the increased vibration is propagated to the transmission case. It turned out that the chain noise becomes large. In order to suppress chain noise, it is conceivable to reinforce the rigidity of the transmission case that supports the bearing or to attach a case cover, but such measures increase the weight and cost of the transmission. Also, depending on the transmission, there are cases where the case cannot be reinforced or the cover cannot be attached due to restrictions on the design layout.

  An object of the present invention is to suppress vibration of a continuously variable transmission and reduce vibration noise generated from the continuously variable transmission.

  A continuously variable transmission according to the present invention includes a fixed sheave integrally provided on a rotating shaft, a hollow shaft portion that slides axially on the rotating shaft and rotates integrally with the rotating shaft, and a proximal end of the hollow shaft portion A continuously variable transmission in which a chain is wound around a groove of the pulley, and provided at a central portion in the axial direction of the hollow shaft portion. An engagement portion that is slidably engaged with the rotation shaft in the axial direction, and a proximal end fitting portion that is provided at a proximal end portion of the hollow shaft portion and is slidably fitted to the outer peripheral surface of the rotation shaft. And a distal end side fitting portion that is provided at the distal end portion of the hollow shaft portion and is slidably fitted to the outer peripheral surface of the rotating shaft, and the position of the antinode of the shaft vibration of the rotating shaft is It arrange | positioned in the axial direction center part of the front end side fitting part.

  In the continuously variable transmission according to the present invention, the excitation force generated in the rotating shaft is concentratedly applied to the front end side fitting portion of the pulley, and the vibration propagated from the bearing supporting the rotating shaft to the transmission case is suppressed. The Thereby, the vibration noise generated from the continuously variable transmission can be reduced.

It is sectional drawing which shows the continuously variable transmission which is one embodiment. It is sectional drawing which shows the generation | occurrence | production state of the bending mode of the secondary axis | shaft when rotating a continuously variable transmission. It is an expanded sectional view showing a part of a secondary axis. It is a load characteristic graph which shows the local maximum contact load of the front end side fitting part of the continuously variable transmission of this invention, and the local maximum contact load of the front end side fitting part which is a comparative example. It is a surface pressure characteristic diagram which shows notionally the size and distribution of surface pressure applied to the direction of vibration and the tip side fitting part about the present invention and a comparative example, (A) shows the characteristic of the present invention, (B ) Shows the characteristics of the comparative example. The result of having measured the generation | occurrence | production state of chain noise about this invention and a comparative example by rotationally driving a continuously variable transmission is shown. It is sectional drawing which shows a part of primary pulley.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the continuously variable transmission 10 has a primary shaft 11 and a secondary shaft 12 as rotating shafts, and the respective shafts are arranged in parallel to each other. Both ends of the primary shaft 11 are rotatably supported by a transmission case (not shown) by bearings 13a and 13b, and both ends of the secondary shaft 12 are rotatably supported by the transmission case by bearings 14a and 14b. Engine torque is input to the primary shaft 11, and the secondary shaft 12 outputs engine torque after shifting to the drive wheels.

  The primary shaft 11 is provided with a pulley, that is, a primary pulley 15. The primary pulley 15 is slid in the axial direction on the primary shaft 11 so as to face the fixed sheave 16 integrally with the primary shaft 11 and the fixed sheave 16. And a movable sheave 17 that is movably mounted. The movable sheave 17 includes a hollow shaft portion 17a that slides in the axial direction on the primary shaft 11 and rotates integrally with the primary shaft 11, and a movable sheave body portion 17b that is integrally provided at the base end portion of the hollow shaft portion 17a. have.

  The secondary shaft 12 is provided with a pulley, that is, a secondary pulley 21. The secondary pulley 21 is slid in the axial direction on the secondary shaft 12 so as to face the fixed sheave 22 integrally with the secondary shaft 12. And a movable sheave 23 that is movably mounted. The movable sheave 23 includes a hollow shaft portion 23a that slides in the axial direction on the secondary shaft 12 and rotates integrally with the secondary shaft 12, and a movable sheave body portion 23b that is integrally provided at the base end portion of the hollow shaft portion 23a. Have.

  Between the power transmission surface 24a of the fixed sheave 16 in the primary pulley 15 and the power transmission surface 24b of the movable sheave main body 17b, a groove 25a whose width is variable by the axial movement of the movable sheave 17 is formed. A groove 25b is formed between the power transmission surface 26a of the fixed sheave 22 in the secondary pulley 21 and the power transmission surface 26b of the movable sheave main body 23b. Chains 27 are mounted in the grooves 25a and 25b of both pulleys and wound around the respective pulleys. When the gear ratio is on the lowest speed side, the winding diameter of the chain 27 with respect to the primary pulley 15 is minimum, and the winding diameter with respect to the secondary pulley 21 is maximum. When the gear ratio is on the highest speed side, the winding diameter with respect to the primary pulley 15 is maximum, and the winding diameter with respect to the secondary pulley 21 is minimum. In FIG. 1, a state in which the winding diameter of the chain 27 around the secondary pulley 21 is the maximum diameter is indicated by a solid line. The position of the chain 27 indicated by a solid line with respect to the primary pulley 15 at this time indicates the minimum winding diameter.

  In FIG. 1, the upper half of the movable sheave 17 is shown closest to the fixed sheave 16, and the lower half is shown farthest from the fixed sheave 16. On the other hand, the movable sheave 23 is shown in a state where the upper half is farthest from the fixed sheave 22, and the lower half is shown in a state closest to the fixed sheave 22.

  A first cylinder 31 is mounted on the hollow shaft portion 17 a of the primary pulley 15, and a partition wall portion 17 c provided on the movable sheave 17 is slidably in contact with the inner peripheral surface of the cylindrical portion 31 a of the cylinder 31. Yes. A second cylinder 32 is fixed to the primary shaft 11, and the tip of the cylinder 32 is in contact with the outer surface of the cylinder 31. A partition wall portion 33 is fixed to the hollow shaft portion 17a, and the partition wall portion 33 is slidably in contact with the inner peripheral surface of the cylindrical portion 32a of the cylinder 32. A first primary oil chamber 34 a is defined by the cylinder 31 and the movable sheave 17, and a second primary oil chamber 34 b is defined by the cylinder 32 and the partition wall 33.

  An oil passage 35 is formed at one end of the primary shaft 11, and the oil passage 35 is connected to the first primary oil via a communication hole 36 formed in the primary shaft 11 and a communication hole 37 formed in the hollow shaft portion 17 a. It communicates with the chamber 34a. An oil passage 38 is formed at the other end of the primary shaft 11, and the oil passage 38 communicates with the second primary oil chamber 34 b through a communication hole 39 formed in the primary shaft 11. The movable sheave 17 of the primary pulley 15 is driven by the hydraulic oil supplied to both primary oil chambers 34a and 34b to a position approaching and separating from the fixed sheave 16, and the width of the groove 25a is adjusted.

  A plunger 41 is attached to the secondary shaft 12, and the plunger 41 has a portion with a different outer diameter, and the cross-sectional shape is stepped. The inner peripheral surface of the cylindrical portion 23 c of the movable sheave 23 is slidably in contact with the large diameter portion 41 a of the plunger 41. A secondary oil chamber 42 is defined by the plunger 41 and the movable sheave 23. A coil spring 43 is mounted between the plunger 41 and the movable sheave 23, and a spring force in a direction toward the fixed sheave 22 is biased to the movable sheave 23 by the coil spring 43.

  An oil passage 44 is formed at one end of the secondary shaft 12, and the oil passage 44 communicates with the secondary oil chamber 42 through a communication hole 45 formed in the secondary shaft 12. By the hydraulic oil supplied to the secondary oil chamber 42, the movable sheave 23 of the secondary pulley 21 is driven to a position approaching and separating from the fixed sheave 22, and the width of the groove 25b is adjusted. A cover member 46 is fixed to the cylindrical portion 23 c of the movable sheave 23, and a balance oil chamber 47 is formed by the cover member 46 and the plunger 41, and lubricating oil in the transmission case flows into the balance oil chamber 47.

  The secondary shaft 12 is provided with an output gear 48, and the engine torque input to the primary shaft 11 is shifted by the continuously variable transmission 10 and output from the output gear 48 to the drive wheels.

  A meshing portion 51 is provided on the inner peripheral surface of the axial direction central portion of the hollow shaft portion 17a of the movable sheave 17 in the primary pulley 15, and this meshing portion 51 is formed of a spline or the like provided on the primary shaft 11. It meshes with the meshing portion so as to be slidable in the axial direction. When the inner diameter portion of the movable sheave body portion 17b is the base end portion of the hollow shaft portion 17a, the hollow shaft portion 17a protrudes toward the end portion of the primary shaft 11 away from the chain 27, and the protruding end is the hollow shaft portion. The tip of 17a is used. A base end side fitting portion 52 that is slidably fitted to the outer peripheral surface of the primary shaft 11 is provided at the base end portion of the hollow shaft portion 17a. On the other hand, a distal end side fitting portion 53 that is slidably fitted to the outer peripheral surface of the primary shaft 11 is provided at the distal end portion of the hollow shaft portion 17a.

  Similarly, a meshing portion 51 is provided on the inner surface of the central portion in the axial direction of the hollow shaft portion 23 a of the movable sheave 23 in the secondary pulley 21, and this meshing portion 51 is formed from a spline or the like provided on the secondary shaft 12. The meshing portion is slidably engaged in the axial direction. When the inner diameter portion of the movable sheave body portion 23b is the base end portion of the hollow shaft portion 23a, the hollow shaft portion 23a protrudes toward the end portion of the secondary shaft 12 away from the chain 27, and the protruding end is the hollow shaft portion. Let it be the tip of 23a. A base end side fitting portion 52 that is slidably fitted to the outer peripheral surface of the secondary shaft 12 is provided at the base end portion of the hollow shaft portion 23a. On the other hand, a distal end side fitting portion 53 that is slidably fitted to the outer peripheral surface of the secondary shaft 12 is provided at the distal end portion of the hollow shaft portion 23a.

  FIG. 2 is a cross-sectional view showing a state of a bending mode generated in the secondary shaft 12 when the continuously variable transmission 10 is rotated. The bending mode is generated by the exciting force of the chain 27 that rotates with the secondary shaft 12.

  A broken line in FIG. 2 indicates a bending moment of the secondary shaft 12 due to the vibration force of the chain 27. As shown in FIG. 2, the amplitude of the bending mode of the secondary shaft 12 decreases toward the both end portions of the secondary shaft 12 with the axial center portion of the proximal end side fitting portion 52 of the movable sheave 23 being reduced, After passing through the peak point, both end surfaces of the secondary shaft 12 become slightly smaller. The shaft vibration at both ends of the secondary shaft 12 is propagated to the transmission case via the bearings 14a and 14b, and the continuously variable transmission 10 generates vibration noise.

  As shown by a broken line in FIG. 2, the bending mode of the secondary shaft 12 is a corrugated node A at the axial center of the base end side fitting portion 52, and the peak point is a corrugated antinode B. When the length of the hollow shaft portion 23a of the movable sheave 23 and the length of the distal end side fitting portion 53 are set so that the axial center portion of the distal end side fitting portion 53 contacts the position of the antinode B, the distal end side fitting is performed. Surface pressure is applied to the antinode B of the secondary shaft 12 at the joint portion 53, and deformation of the contact portion increases. As a result, the rigidity of the contact portion is increased, and the amplitude of the bending mode of the secondary shaft 12 is decreased. Thus, if the front end side fitting part 53 is set in the position of the antinode B of the bending mode of the secondary shaft 12, the secondary pulley 21 will be a vibration suppression structure, the vibration transmitted to the bearing 14a will be suppressed, and from the bearing 14a. Vibration transmitted to the transmission case is suppressed. Since vibration transmitted to the transmission is suppressed, vibration noise generated from the continuously variable transmission 10 due to the vibration force of the chain 27 is reduced.

  The vibration waveform shown in FIG. 2 indicates a bending mode that appears when the secondary shaft 12 is rotated at a rotational speed between 4200 and 4800 rpm.

  FIG. 3 is an enlarged cross-sectional view showing a part of the secondary shaft 12, in which the position of the node A and the position of the antinode B are shown enlarged, and the distance between the node A and the antinode B is L0. In FIG. 3, the maximum winding diameter of the chain 27 around the secondary pulley 21 is indicated by Dmax, and the base end surface 52 a of the base end side fitting portion 52 of the movable sheave 23 and the tip end surface 53 a of the tip end side fitting portion 53 are shown. The axial length between them is indicated by L1. As shown in FIG. 3, the axial length L1 of the movable sheave 23 is set to a value smaller than the maximum winding diameter Dmax (L1 <Dmax).

  Even when the movable sheave 23 moves in the axial direction, the length of the meshing portion 51 needs to be set to a predetermined value in order to maintain the meshing portion 51 meshed with the meshing portion of the secondary shaft 12. The length of 51 cannot be shortened. If the axial length L1 of the movable sheave 23 is set to a value shorter than the maximum winding diameter Dmax while maintaining the lengths of the meshing part 51 and the base end side fitting part 52, The central portion in the axial direction is set to the position of the antinode B in the bending mode of the secondary shaft 12 and the surface pressure applied to the distal end side fitting portion 53, that is, the contact per unit area between the secondary shaft 12 and the movable sheave 23. The load is increased. As the surface pressure increases, the deformation of the contact portion of the secondary shaft 12 increases, and the rigidity of the contact portion increases. As a result, the bending mode amplitude of the secondary shaft 12 is suppressed in combination with the arrangement of the front end side fitting portion 53 at the position of the antinode B of the bending mode of the secondary shaft 12 caused by the vibration force of the chain 27. Is done.

  In particular, at a low speed gear ratio at which the winding diameter of the chain 27 is maximum, a large fastening load is applied to the movable sheave main body 23b of the secondary pulley 21 so as to bend in the direction of expanding the groove 25b. By increasing the surface pressure of the distal end side fitting portion 53, the vibration suppressing effect of the secondary shaft 12 can be enhanced.

  FIG. 4 is a load characteristic graph showing the local maximum contact load of the front end side fitting portion 53 of the continuously variable transmission 10 of the present invention and the local maximum contact load of the front end side fitting portion which is a comparative example. In the present invention, L1 / Dmax is set to 0.94. On the other hand, L1 / Dmax was set to about 1 in the comparative example. As shown in FIG. 4, in the present invention, the local maximum contact load (surface pressure) can be increased more than twice as compared with the comparative example.

  FIG. 5 is a surface pressure characteristic diagram conceptually showing the vibration direction and the size and distribution of the surface pressure applied to the distal end fitting portion of the present invention and the comparative example described above, and FIG. FIG. 5B shows the characteristics of the comparative example. As shown in FIG. 5, assuming that the vibration direction of the secondary shaft 12 is the V direction, a radial contact load is applied to the lower pressure receiving region E and the upper pressure receiving region F, respectively. In the present invention, as shown in FIG. 5A, the contact load in each of the pressure receiving regions E and F is larger than the contact load in the pressure receiving regions E and F of the comparative example shown in FIG. Become. Thereby, as shown with a dashed-two dotted line, the bending mode which generate | occur | produces in the secondary axis | shaft 12 is suppressed, As a result, the vibration added to the bearing 14a can be reduced. The lower pressure receiving region E has a larger contact load than the upper pressure receiving region F.

  FIG. 6 shows the result of measuring the state of occurrence of chain noise for the present invention and the comparative example by rotationally driving the continuously variable transmission. In FIG. 6, the horizontal axis represents the rotational speed of the secondary shaft 12, and the vertical axis represents the chain sound. The solid line indicates the chain sound of the present invention, and the alternate long and short dash line indicates the chain sound of the comparative example. In the present invention, it has been found that chain noise can be reduced, and as shown in FIG. 6, the rotational speed is particularly significantly reduced in the range of 4300 to 4500 rpm.

  FIG. 7 is a cross-sectional view showing a part of the primary pulley 15. The primary pulley 15 is the same as the secondary pulley 21, and the secondary shaft 12 is arranged by disposing the distal end fitting portion 53 at the position of the antinode B in the bending mode of the primary shaft 11 caused by the vibration force of the chain 27. The amplitude of the bending mode is reduced, and the vibration propagated to the bearing 13a is suppressed.

  Further, similarly to the secondary pulley 21, the axial length L 1 between the proximal end surface 52 a of the proximal end fitting portion 52 of the movable sheave 17 and the distal end surface 53 a of the distal end fitting portion 53 is also the primary pulley 15. The maximum winding diameter Dmax of the chain 27 with respect to the primary pulley 15 is set shorter.

  If the primary pulley 15 has a vibration suppressing structure in addition to the secondary pulley 21, the occurrence of chain noise can be further reduced. However, at least one of the secondary pulley 21 and the primary pulley 15 may have a vibration suppressing structure.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.

11 Primary shaft 12 Secondary shaft 15 Primary pulley 16 Fixed sheave 17 Movable sheave 17a Hollow shaft portion 17b Movable sheave body portion 21 Secondary pulley 22 Fixed sheave 23 Movable sheave 23a Hollow shaft portion 23b Movable sheave body portion 27 Chain 34a, 34b Primary oil chamber 42 Secondary oil chamber 51 Engagement portion 52 Base end side fitting portion 52a Base end surface 53 Front end side fitting portion 53a Front end surface

Claims (3)

A fixed sheave integrally provided on the rotary shaft, a hollow shaft portion that slides axially on the rotary shaft and rotates integrally with the rotary shaft, and a movable sheave integrally provided on the proximal end portion of the hollow shaft portion A continuously variable transmission including a pulley including a movable sheave having a main body, wherein a chain is wound around the groove of the pulley;
A meshing portion provided at a central portion in the axial direction of the hollow shaft portion and meshing slidably in the axial direction with the rotating shaft;
A proximal end fitting portion provided at a proximal end portion of the hollow shaft portion and slidably fitted to an outer peripheral surface of the rotating shaft;
A tip-side fitting portion that is provided at a tip portion of the hollow shaft portion and slidably fits on an outer peripheral surface of the rotating shaft;
A continuously variable transmission in which the position of the antinode of the shaft vibration of the rotating shaft is disposed at the axially central portion of the distal end side fitting portion.   The continuously variable transmission according to claim 1, wherein an axial length between a proximal end surface of the proximal end side fitting portion and a distal end surface of the distal end side fitting portion is set to a maximum winding around the pulley of the chain. A continuously variable transmission that is smaller than the diameter.   The continuously variable transmission according to claim 1 or 2, wherein the rotating shaft is a secondary shaft.

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