Continuously variable transmission for vehicles

Abstract

In a continuously variable transmission (1) for a vehicle, a speed change mechanism (2) comprises: a primary pulley (3), a secondary pulley (4), and a belt (V) wound around the primary pulley (3) and the secondary pulley (4). A spring (Sp) is provided on the secondary pulley (4) to generate a force in a direction of narrowing the groove width of a V-shaped groove (43) of the secondary pulley (4). When the vehicle reaches a predetermined speed or higher, the speed ratio of the speed change mechanism (2) becomes higher than the lowest speed ratio due to the centrifugal oil pressure of the oil (OL) stored in the pressure receiving chamber (R1, R2) of the primary pulley (3).

Description

Technical Field

[0001] The present invention relates to a continuously variable transmission for a vehicle. Background Art

[0002] The speed change mechanism of a continuously variable transmission for a vehicle has a basic structure in which a belt is wound around a pair of pulleys (a primary pulley and a secondary pulley) (for example, Patent Document 1).

[0003] Each pulley includes a fixed pulley and a sliding pulley provided on a shaft portion of the fixed pulley so as to be movable in the rotation axis direction.

[0004] In the speed change mechanism, the oil pressure supplied to the pulley pressure receiving chamber attached to the sliding pulley is adjusted to change the groove width between the fixed pulley and the sliding pulley, thereby changing the belt winding radius of a pair of pulleys (primary pulley and secondary pulley).

[0005] A return spring is provided on the secondary pulley to prevent the belt from slipping when the vehicle is towed. When the vehicle is towed without supplying oil pressure to the pulley pressure chamber, the return spring generates a belt clamping force between the fixed pulley and the sliding pulley to prevent the belt from slipping.

[0006] The clamping force of the secondary pulley controls the occurrence of belt slip. No return spring is provided on the primary pulley side. In addition, when being pulled, no oil pressure is supplied to the pulley pressure chamber on the primary pulley side and the pulley pressure chamber on the secondary pulley side.

[0007] Here, the speed ratio of the speed change mechanism when being pulled is determined by the magnitude of the thrust difference between the primary pulley and the secondary pulley. In this way, since the clamping force of the secondary pulley side provided with the return spring becomes larger, the speed ratio of the speed change mechanism becomes the lowest gear state when being pulled.

[0008] This means that the speed ratio of the transmission mechanism is in the lowest gear state from the input shaft side, but is in the highest gear state from the output shaft side. Therefore, as the vehicle speed increases when being towed, the primary pulley reaches a very high speed.

[0009] When the primary pulley reaches an extremely high rotation speed, problems may occur, such as affecting the durability of a bearing in contact with the primary pulley.

[0010] Therefore, it is required to be able to suppress the rotation speed of the primary pulley during pulling.

[0011] Prior art literature

[0012] Patent Literature

[0013] Patent Document 1: Japanese Patent Application Publication No. 2008-75792 Summary of the invention

[0014] The vehicle continuously variable transmission of the present invention has a speed change mechanism including a primary pulley, a secondary pulley, and an annular member wound around the primary pulley and the secondary pulley.

[0015] The secondary pulley is provided with a force applying member that generates a force in a direction of narrowing the groove width of the secondary pulley.

[0016] When the vehicle reaches a predetermined speed or higher while being towed, the speed ratio of the speed change mechanism is shifted to a higher gear side than the lowest gear ratio by the centrifugal oil pressure of the oil stored in the pulley pressure receiving chamber of the primary pulley.

[0017] According to the present invention, when the vehicle reaches a predetermined speed or higher and the primary pulley rotates at a high speed, the oil stored in the pulley pressure chamber of the primary pulley generates centrifugal force, generating a centrifugal oil pressure effect of thrust in a direction narrowing the groove width of the primary pulley.

[0018] As a result, the differential thrust between the primary pulley and the secondary pulley is reduced, and the speed ratio of the speed change mechanism is shifted to the high gear side.

[0019] Since the change in the speed ratio acts in the direction of decreasing the rotation speed of the primary pulley as the vehicle speed increases, it is possible to suppress the rotation speed of the primary pulley from reaching an extremely high level. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a diagram for explaining the main structure of the continuously variable transmission.

[0021] Figure 2 This is a diagram for explaining the main structure around the planetary gear set of the forward / reverse switching mechanism.

[0022] Figure 3 It is a diagram for explaining the primary pulley and the forward / reverse switching mechanism and their surroundings of the continuously variable transmission.

[0023] Figure 4 This is a diagram for explaining the function of the pressure-receiving chamber (pulley pressure-receiving chamber) when the vehicle is towed. DETAILED DESCRIPTION

[0024] Hereinafter, an embodiment of the present invention will be described by taking a case of a belt-type continuously variable transmission 1 for a vehicle as an example.

[0025] Figure 1 It is a diagram for explaining the main structure of the continuously variable transmission 1 .

[0026] Figure 2 This is a diagram for explaining the main structure around the planetary gear set 6 of the forward / reverse switching mechanism 5 .

[0027] Figure 3It is a diagram for explaining the primary pulley 3 and the forward / reverse travel switching mechanism 5 and their surroundings of the continuously variable transmission 1 .

[0028] like Figure 1 As shown, in the belt-type continuously variable transmission 1 , the rotational driving force of an engine (not shown) as a driving source is input to the forward / reverse switching mechanism 5 via a torque converter (not shown).

[0029] The forward / reverse switching mechanism 5 includes a planetary gear set 6 , a forward clutch 51 , and a reverse brake 52 .

[0030] When the forward clutch 51 is engaged, the planetary gear set 6 of the forward / reverse switching mechanism 5 outputs the rotation input from the torque converter side to the speed change mechanism 2 in a clockwise rotation. When the reverse brake 52 is engaged, the rotation input from the torque converter side is output to the speed change mechanism 2 in a counterclockwise rotation.

[0031] (Planetary Gear Set)

[0032] like Figure 2 As shown, the planetary gear set 6 includes a sun gear 61 that rotates integrally with the rotation transmission shaft 9 and a ring gear 62 that rotates integrally with the clutch drum 7 , with a pair of pinion gears 63A, 63B located between the sun gear 61 and the ring gear 62 .

[0033] The pinion 63A and the pinion 63B are arranged so that the teeth provided on the outer periphery mesh with each other. The pinion 63A meshes with the outer periphery of the sun gear 61, and the pinion 63B meshes with the inner periphery of the ring gear 62. The planetary gear set 6 is a double pinion type planetary gear mechanism. Alternatively, it may be a single pinion type planetary gear mechanism.

[0034] The pinion gear 63A is supported by a pinion shaft 631 via a needle bearing NB. Both ends of the pinion shaft 631 are supported by side plates 640 and 641 of the gear carrier 64 .

[0035] In the planetary gear set 6 , when the sun gear 61 and / or the ring gear 62 rotate about the rotation axis X1 , the pinion 63A supported by the pinion shaft 631 and the pinion 63B meshing with the pinion 63A revolve around the rotation axis X1 while rotating.

[0036] The planetary gear set 6 is accommodated inside the clutch drum 7 together with the forward clutch 51 .

[0037] The clutch drum 7 includes a bottom wall portion 71 that is annular when viewed from the rotation axis X1 direction, an outer peripheral wall portion 72 that surrounds the entire outer circumference of the bottom wall portion 71 , and an inner peripheral wall portion 73 that surrounds the entire inner circumference of the bottom wall portion 71 .

[0038] The ring gear 62 of the planetary gear set 6 is spline-fitted to the inner circumference of the front end 72 a side of the outer peripheral wall portion 72 .

[0039] The inner peripheral wall portion 73 is cylindrical along the rotation axis X1. The peripheral wall portion 73 is formed from the speed change mechanism 2 side ( Figure 2 The left side of the device is inserted into the cylindrical supporting wall portion 12 which serves as the fixed side member.

[0040] In this state, the clutch drum 7 is supported on the outer periphery of the support wall portion 12 in a state where the clutch drum 7 is allowed to rotate about the rotation axis X1 .

[0041] A connecting portion 74 extending toward the inner diameter side (rotation axis X1 side) around the supporting wall portion 12 is provided at the front end of the inner peripheral wall portion 73 , and a cylindrical supporting tube 75 is provided on the inner diameter side of the connecting portion 74 .

[0042] The support tube 75 extends linearly from the lower end of the connecting portion 74 in a direction away from the sun gear 61 (right direction in the figure). The front end 75a of the support tube 75 extends to the inner diameter side of the support wall portion 12, and faces the front end 14a of the cylindrical shaft 14 pressed into the inner circumference of the support wall portion 12 with a gap therebetween.

[0043] Needle bearing NB1 is provided between the outer periphery of support tube 75 and the inner periphery of peripheral wall 73. Needle bearing NB1 is interposed between connection portion 74 and front end 12a of support wall 12 in the direction of rotation axis X1 to prevent direct contact between connection portion 74 and support wall 12.

[0044] The inner periphery of the support cylinder 75 is supported on the outer periphery of the rotation transmission shaft 9 via a bushing BS (a metal ring with low friction resistance). The clutch drum 7 having the support cylinder 75 is supported by the support wall portion 12 rotatably around the rotation axis X1 while the inclination relative to the rotation axis X1 is restricted by the support cylinder 75.

[0045] The rotation transmission shaft 9 is an output shaft of a torque converter (not shown). The front end 9a of the rotation transmission shaft 9 penetrates the inner diameter side of the support tube 75 in the direction of the rotation axis X1, and the sun gear 61 is integrally formed on the outer circumference of the front end 9a of the rotation transmission shaft 9 at a position avoiding interference with the support tube 75.

[0046] On the rotation transmission shaft 9 , the sun gear 61 projects from the outer circumference at a position away from the torque converter side (right side in the figure) from the front end 9 a toward the radially outer side of the rotation axis X1 .

[0047] The needle roller bearing NB2 is interposed between one side surface 61 a of the sun gear 61 in the direction of the rotation axis X1 and the contact portion 74 on the clutch drum 7 side.

[0048] The needle roller bearing NB3 is interposed between the other side surface 61 b ​​of the sun gear 61 in the direction of the rotation axis X1 and the side plate portion 640 .

[0049] The front end 9 a side of the rotation transmission shaft 9 is inserted into the inner side of the cylindrical connecting portion 643 provided on the inner diameter side of the gear carrier 64 .

[0050] A bushing BS is provided between the outer periphery of the rotation transmission shaft 9 and the inner periphery of the connection portion 643, and the connection portion 643 of the carrier 64 is supported by the rotation transmission shaft 9 via the bushing BS. The connection portion 643 of the carrier 64 and the rotation transmission shaft 9 are relatively rotatable about the rotation axis X1.

[0051] The side plate portion 640 of the carrier 64 extends radially outward from the end portion of the coupling portion 643 on the torque converter side, and the other end 311 b of the shaft portion 311 of the primary pulley 3 abuts against the side plate portion 640 in the direction of the rotation axis X1.

[0052] In this state, the inner periphery of the shaft portion 311 is spline-fitted with the outer periphery of the connection portion 643 , and the connection portion 643 of the carrier 64 and the shaft portion 311 on the speed change mechanism 2 side are connected to each other in a relatively non-rotatable manner.

[0053] In the planetary gear set 6 , the sun gear 61 is an input portion to which rotation is input from the torque converter side, and the carrier 64 is an output portion to which rotation is output to the speed change mechanism side.

[0054] However, when the vehicle equipped with the continuously variable transmission 1 is towed, the input portion and the output portion are reversed.

[0055] That is, when the vehicle equipped with the continuously variable transmission 1 is towed, the rotation of the drive wheels is input from the primary pulley 3 of the speed change mechanism 2 to the planetary gear set 6 .

[0056] (Speed ​​Shifting Mechanism)

[0057] like Figure 1 As shown, the speed change mechanism 2 includes a pair of pulleys (a primary pulley 3 and a secondary pulley 4) and a belt V (an endless member) wound around the pair of pulleys.

[0058] In the speed change mechanism 2, by changing the winding radius of the belt V on a pair of pulleys (primary pulley 3, secondary pulley 4), the rotation input from the forward / reverse switching mechanism 5 is changed to a desired speed change and output to the final reduction mechanism (not shown).

[0059] Here, in the continuously variable transmission 1 of this embodiment, no clutch is provided on the downstream side of the speed change mechanism 2 on the power transmission path of the rotational driving force of the engine (driving source). Therefore, it is a form in which the power transmission between the speed change mechanism 2 and the drive wheel (not shown) side cannot be cut off.

[0060] Therefore, when the vehicle equipped with the continuously variable transmission 1 is towed, the rotation of the drive wheel is input to the speed change mechanism 2, so that the pair of pulleys (primary pulley 3 and secondary pulley 4) constituting the speed change mechanism 2 rotate. Furthermore, the rotation input from the drive wheel side to the speed change mechanism 2 is finally input to the forward / reverse switching mechanism 5 side.

[0061] The primary pulley 3 has a fixed pulley 31 (fixed pulley) and a sliding pulley 32 (movable pulley).

[0062] The fixed pulley 31 includes a shaft portion 311 disposed along the rotation axis X1 and a pulley portion 312 extending radially outward from the outer periphery of the shaft portion 311 .

[0063] The bearings 34A and 34B are respectively inserted and fixed to one end 311 a and the other end 311 b in the longitudinal direction of the shaft portion 311 .

[0064] One end 311 a and the other end 311 b of the shaft portion 311 are rotatably supported by the support hole 15 on the side cover 13 and the support portion 101 on the transmission case 10 via bearings 34A and 34B, respectively.

[0065] In this state, the gear carrier 64 (see Figure 3 ) is connected to the other end 311b of the shaft portion 311 in a non-rotatable manner.

[0066] The slide pulley 32 includes an annular base portion 321 externally inserted into the shaft portion 311 of the fixed pulley 31 , and a pulley portion 322 extending radially outward from the outer periphery of the annular base portion 321 .

[0067] The annular base portion 321 of the sliding pulley 32 is spline-fitted to the outer periphery of the shaft portion 311 , and the sliding pulley 32 is provided in a state where relative rotation with the fixed pulley 31 is restricted and movable in the axial direction (rotation axis X1 direction) of the shaft portion 311 .

[0068] The pulley portion 312 of the fixed pulley 31 and the pulley portion 322 of the sliding pulley 32 face each other with a gap therebetween in the direction of the rotation axis X1.

[0069] In the primary pulley 3 , a V-shaped groove 33 around which the belt V is wound is formed between the pulley surface 312 a of the fixed pulley 31 and the pulley surface 322 a of the slide pulley 32 .

[0070] like Figure 3 As shown, on the outer diameter side of the pulley portion 322, a cylindrical cylinder portion 323 is provided on a pressure receiving surface 322b on the opposite side of the pulley surface 322a.

[0071] The cylinder portion 323 is provided along the direction of the rotation axis X1 and is formed to have a predetermined length L1 in a direction away from the pulley portion 322 .

[0072] The outer peripheral portion 35 a of the front plunger 35 abuts against the inner periphery of the cylinder portion 323 .

[0073] The D-ring 8 is attached to the outer peripheral portion 35 a of the front plunger 35 , and the gap between the inner periphery of the cylinder portion 323 and the outer peripheral portion 35 a is sealed by the D-ring 8 .

[0074] The inner peripheral portion 35 b of the front plunger 35 abuts against the outer periphery of the annular base portion 321 of the slide pulley 32 from the radially outer side.

[0075] The D-ring 8 is attached to the inner peripheral portion 35 b of the front plunger 35 , and the gap between the outer periphery of the annular base 321 and the inner peripheral portion 35 b is sealed by the D-ring 8 .

[0076] In the primary pulley 3, a space between the front plunger 35 and the pulley portion 322 forms a pressure receiving chamber R1 (pulley pressure receiving chamber) to which the operating oil pressure is supplied.

[0077] The annular base portion 321 is provided with a small diameter portion 324 at an end portion opposite to the pulley portion 322 .

[0078] The annular rear plunger 36 is pressed into the small diameter portion 324. The inner peripheral portion 36b of the rear plunger 36 is pressed into the step portion of the small diameter portion 324 on the pulley portion 322 side (right side in the figure) and fixed.

[0079] In this state, the rear plunger 36 is set in a state where the relative rotation with the annular base 321 is restricted and cannot move in the direction of the rotation axis X1.

[0080] The outer peripheral portion 36 a of the rear plunger 36 abuts against the inner periphery of the cylindrical peripheral wall portion 372 of the rear cylinder 37 from the rotation axis X1 side.

[0081] The D-ring 8 is attached to the outer peripheral portion 36 a of the rear plunger 36 , and the gap between the inner periphery of the peripheral wall portion 372 and the outer peripheral portion 36 a is sealed by the D-ring 8 .

[0082] The rear cylinder 37 is composed of a disc portion 371 inserted outside the shaft portion 311 and a peripheral wall portion 372 surrounding the entire outer circumference of the disc portion 371 .

[0083] The shaft portion 311 is press-fitted into the inner circumference 371 b of the disc portion 371 , and the inner circumference 371 b of the disc portion 371 is held between the step portion 314 provided on the shaft portion 311 and the bearing 34A externally inserted on the shaft portion 311 .

[0084] The bearing 34A is positioned in the direction of the rotation axis X1 by a nut N screwed onto the outer periphery of the shaft portion 311 , and movement of the rear cylinder 37 adjacent to the bearing 34A in a direction away from the slide pulley 32 is restricted by the bearing 34A.

[0085] The peripheral wall portion 372 is formed with an outer diameter smaller than the inner diameter of the cylindrical cylinder portion 323 , and a front end portion 372 a of the peripheral wall portion 372 abuts against the front plunger 35 inside the cylinder portion 323 in the direction of the rotation axis X1 .

[0086] The front end portion 372 a of the peripheral wall portion 372 restricts movement of the front plunger 35 in a direction away from the pulley portion 322 (leftward in the figure).

[0087] The outer peripheral portion 35 a and the inner peripheral portion 35 b of the front plunger 35 are offset in the direction of the rotation axis X1 , and the outer peripheral portion 35 a is located closer to the pulley portion 322 of the slide pulley 32 than the inner peripheral portion 35 b .

[0088] The front end portion 372 a of the peripheral wall portion 372 abuts against a region on the outer peripheral portion 35 a side of the front plunger 35 in the direction of the rotation axis X1 .

[0089] In the primary pulley 3, a space surrounded by the rear plunger 36, the front plunger 35, and the peripheral wall portion 372 of the rear cylinder 37 serves as a second pressure receiving chamber R2 (pulley pressure receiving chamber) to which the operating oil pressure is supplied.

[0090] In the sliding pulley 32, the pressure receiving chamber R1 and the pressure receiving chamber R2 are adjacent to each other on the inner side (left side in the figure) viewed from the pulley surface 322a, sandwiching the front plunger 35. The pressure receiving chamber R1 and the pressure receiving chamber R2 constitute the pulley pressure receiving chamber on the primary pulley 3 side.

[0091] Therefore, the pressure receiving area of ​​each pulley pressure receiving chamber (each pressure receiving chamber R1, R2) can be reduced, so that the outer diameter of the primary pulley 3 (pulley parts 322, 312) can be reduced.

[0092] The shaft portion 311 of the fixed pulley 31 is provided with an in-shaft oil passage 313 for supplying actuating oil pressure to the pressure receiving chambers R1 and R2 .

[0093] In the shaft portion 311, the shaft inner oil passage 313 opens at one end 311a toward the side cover 13 side (left side in the figure). The support cylinder 152 provided in the side cover 13 is loosely fitted on the side cover 13 side (left side in the figure) of the shaft inner oil passage 313. The cylindrical bushing 153 is externally fitted on the support cylinder 152, and the side cover 13 side of the shaft portion 311 is rotatably supported by the bushing 153 internally fitted in the shaft inner oil passage 313.

[0094] In this state, the seal ring S provided on the outer periphery of the bushing 153 seals the gap between the outer periphery of the bushing 153 and the inner periphery of the in-shaft oil passage 313 .

[0095] The support hole 15 of the bearing 34A is opened in the side cover 13 at the portion facing the transmission case 10. A recess 151 is formed in the center of the support hole 15 when viewed from the direction of the rotation axis X1 to avoid interference with the shaft portion 311 of the fixed pulley 31. The support cylinder 152 is provided in the center of the recess 151.

[0096] The oil pressure (oil OL) is supplied to the support cylinder 152 from the oil pressure control circuit (not shown) via the oil passage 131 in the side cover. The oil pressure supplied to the support cylinder 152 is supplied to the pressure receiving chambers R1 and R2 (pulley pressure receiving chambers) attached to the sliding pulley 32 through the shaft oil passage 313.

[0097] In the primary pulley 3, the sliding pulley 32 is displaced in the direction of the rotation axis X1 by adjusting the supply pressure to the pressure receiving chambers R1 and R2 (pulley pressure receiving chambers) attached to the sliding pulley 32. As a result, the groove width of the V-shaped groove 33 between the pulley surfaces 312a and 322a changes according to the supply pressure of the oil OL, thereby changing the winding radius of the belt V of the primary pulley 3.

[0098] like Figure 1 As shown, the secondary pulley 4 includes a fixed pulley 41 (fixed pulley) and a sliding pulley 42 (movable pulley).

[0099] The fixed pulley 41 includes a shaft portion 411 (pulley shaft) disposed along the rotation axis X2 and a pulley portion 412 extending radially outward from the outer periphery of the shaft portion 411 .

[0100] The slide pulley 42 includes an annular base portion 421 externally inserted into the shaft portion 411 of the fixed pulley 41 , and a pulley portion 422 extending radially outward from the outer periphery of the annular base portion 421 .

[0101] The pulley portion 412 of the fixed pulley 41 and the pulley portion 422 of the sliding pulley 42 face each other with a gap therebetween in the direction of the rotation axis X2.

[0102] In the secondary pulley 4 , a V-shaped groove 43 around which the belt V is wound is formed between the pulley surface 412 a of the fixed pulley 41 and the pulley surface 422 a of the slide pulley 42 .

[0103] The shaft portion 411 of the fixed pulley 41 has bearings 44A and 44B externally inserted at one end portion 411 a and the other end portion 411 b in the direction of the rotation axis X2 .

[0104] The other end portion 411 b of the shaft portion 411 in the direction of the rotation axis X2 is rotatably supported by the support portion 102 on the transmission case 10 side via a bearing 44B.

[0105] One end portion 411 a of the shaft portion 411 in the direction of the rotation axis X2 is rotatably supported by the support hole 16 on the side cover 13 via a bearing 44A.

[0106] The support hole 16 of the bearing 44A opens in the side cover 13 at a portion facing the transmission case 10. A recess 161 is formed in the center of the support hole 16 to avoid interference with the shaft portion 411 of the fixed pulley 41 when viewed from the rotation axis X2.

[0107] A support tube 162 is provided in the center of the recessed portion 161 . The support tube 162 protrudes toward the transmission 10 side (right side in the figure), and the front end side of the support tube 162 is loosely fitted in the shaft oil passage 413 of the fixed pulley 41 .

[0108] A cylindrical bushing 163 is externally fitted on the support tube 162 , and the side cover 13 side of the shaft portion 411 is rotatably supported by the bushing 163 which is internally fitted in the in-shaft oil passage 413 .

[0109] In this state, the seal ring S provided on the outer periphery of the bushing 163 seals the gap between the outer periphery of the bushing 163 and the inner periphery of the in-shaft oil passage 413 .

[0110] The shaft oil passage 413 opens at one end 411a of the shaft 411. The shaft oil passage 413 extends linearly in the shaft 411 along the rotation axis X2 of the fixed pulley 41, and crosses the inner diameter side of the sliding pulley 42 inserted outside the shaft 411 in the rotation axis X2 direction.

[0111] An oil hole 414 is provided at the front end side (right side in the figure) of the in-shaft oil passage 413 so as to communicate with the in-shaft oil passage 413 and the outer periphery of the shaft portion 411 .

[0112] The support cylinder 162 is supplied with hydraulic pressure from a hydraulic control circuit (not shown) via the oil passage 132 in the side cover. The hydraulic pressure supplied to the support cylinder 162 is supplied to the pressure receiving chamber R3 located on the outer diameter side of the shaft portion 411 via the in-shaft oil passage 413 .

[0113] In the secondary pulley 4, the supply pressure to the pressure receiving chamber R3 (pulley pressure receiving chamber) attached to the slide pulley 42 is adjusted, so that the slide pulley 42 is displaced in the direction of the rotation axis X2. As a result, the groove width of the V-shaped groove 43 between the pulley surfaces 412a and 422a changes according to the supply pressure, thereby changing the winding radius of the belt V of the secondary pulley 4.

[0114] The pulley portion 422 of the slide pulley 42 is provided with a cylinder portion 423 on a pressure receiving surface 422 b opposite to a pulley surface 422 a .

[0115] The cylinder portion 423 is provided along the direction of the rotation axis X2 and is formed to have a predetermined length L2 in a direction away from the pulley portion 422 .

[0116] The outer peripheral portion 45 a of the plunger 45 abuts against the inner periphery of the cylinder portion 423 .

[0117] The D-ring 8 is attached to the outer peripheral portion 45 a of the plunger 45 , and the gap between the inner periphery of the cylinder portion 423 and the outer peripheral portion 45 a is sealed by the D-ring 8 .

[0118] A cylindrical fitting portion 451 is provided on the inner diameter side of the plunger 45. The fitting portion 451 is spline-fitted to the outer periphery of the shaft portion 411 of the fixed pulley 41. The fitting portion 451 of the plunger 45 is positioned between the bearing 44B and the step portion 411c of the shaft portion 411 in the direction of the rotation axis X2.

[0119] The plunger 45 extends the outer diameter side of the annular base portion 421 of the slide pulley 42 in a region adjacent to the fitting portion 451 in a direction approaching the pulley portion 422 (leftward in the figure), and then bends toward the outer diameter side.

[0120] In the plunger 45, one end of the spring Sp contacts the region 452 bent on the outer diameter side from the direction of the rotation axis X2. The other end of the spring Sp contacts the pressure receiving surface 422b of the pulley portion 422. The spring Sp is set in a compressed state in the direction of the rotation axis X2, and the sliding pulley 42 is pressed in the direction of reducing the groove width of the V-shaped groove 43 by the force acting from the spring Sp.

[0121] This is for maintaining the clamping force of the belt V in the secondary pulley 4 when the engine (driving source) is stopped without supplying oil from the hydraulic control circuit to the pressure receiving chambers R1, R2, R3 on the speed change mechanism 2 side.

[0122] Furthermore, even when the vehicle equipped with the continuously variable transmission 1 is being towed, the engine (driving source) is in a stopped state, and the supply of oil pressure from the oil pump driven by the engine to the pressure receiving chambers R1 , R2 , and R3 is stopped.

[0123] Here, the biasing force of the spring Sp acts in a direction to change the speed ratio of the speed change mechanism 2 to the lowest speed side, and in a direction to increase the winding radius of the belt V of the secondary pulley 4 .

[0124] Furthermore, if the winding radius of the belt V of the secondary pulley 4 increases, the winding radius of the belt V of the primary pulley 3 decreases when oil is not supplied to the pressure receiving chambers R1 and R2 on the primary pulley 3 side.

[0125] Therefore, when the engine (drive source) is stopped due to the lack of oil supply from the hydraulic control circuit, the speed ratio of the speed change mechanism 2 becomes the lowest speed ratio or a speed ratio close to the lowest speed ratio.

[0126] In this state, when the vehicle equipped with the continuously variable transmission 1 is towed, the rotation input from the drive wheel side to the secondary pulley 4 is accelerated by the primary pulley 3 and output.

[0127] As described above, the shaft portion 311 of the primary pulley 3 is connected to the carrier 64 (connection portion 643 ) of the planetary gear set 6 . Therefore, the rotation of the primary pulley 3 at a higher speed is input to the carrier 64 of the planetary gear set 6 .

[0128] Thus, as the running speed of the vehicle increases while being towed, the primary pulley 3 and the carrier 64 of the planetary gear set 6 rotate at a higher speed.

[0129] Furthermore, when the vehicle's speed when being towed reaches a specified speed or above, the durability of the bearings 34A and 34B supporting the shaft 311 of the primary pulley 3 and the needle bearings NB2 and NB3 on both sides of the sun gear 61 in the planetary gear set 6 will be affected.

[0130] This is because when the vehicle is towed, the engine (driving source) is stopped and lubricating oil OL cannot be supplied from the hydraulic control circuit to the bearings 34A, 34B and the needle bearings NB2, NB3.

[0131] In particular, when the ignition switch is turned off while the vehicle is being towed, the power supply from the battery and the generator stops. Therefore, not only the engine (drive source) but also the electric oil pump stops, and the oil pressure supply of the electric oil pump is not performed. In addition, all actuators for oil pressure control also stop.

[0132] Therefore, the lubricating oil OL is not newly supplied to the bearings 34A and 34B, the needle roller bearings NB2 and NB3, and the like.

[0133] Figure 4 This is a diagram for explaining the function of the pressure-receiving chambers R1 and R2 (pulley pressure-receiving chambers) when the vehicle is towed. Figure 4 (a) is a diagram showing the state of the oil OL remaining in the pressure receiving chamber R1 when the vehicle equipped with the continuously variable transmission 1 stops in a state where the oil OL is not supplied from the hydraulic control circuit. Figure 4 (b) is a diagram for explaining the effect of the oil OL remaining in the pressure receiving chamber R1 when the vehicle equipped with the continuously variable transmission 1 is towed (when being towed) without supply of the oil OL from the hydraulic control circuit.

[0134] In addition, Figure 4 In the figure, the cross-hatching indicates the residual oil OL.

[0135] As described above, in the continuously variable transmission 1 of the present embodiment, the D-ring 8 having high sealing performance is adopted for sealing the front plunger 35 and the rear plunger 36 .

[0136] Specifically, in the slide pulley 32, the gap between the outer peripheral portion 35a of the front plunger 35 and the inner periphery of the cylinder portion 323 and the gap between the inner peripheral portion 35b of the front plunger 35 and the outer periphery of the annular base 321 are sealed by the D ring 8. Therefore, the pressure receiving chamber R1 is oil-sealed.

[0137] The gap between the outer peripheral portion 36a of the rear plunger 36 and the inner peripheral portion of the peripheral wall portion 372 of the rear cylinder 37 is sealed by the D ring 8, and the inner peripheral portion 36b of the rear plunger 36 is pressed into the small diameter portion 324 of the annular base 321. Therefore, the pressure receiving chamber R2 is also oil-sealed.

[0138] In the shaft oil passage 313 that supplies oil to the pressure receiving chambers R1 and R2, a gap between the inner periphery of the shaft oil passage 313 and the outer periphery of the bushing 153 fitted in the shaft oil passage 313 is sealed by a seal ring S. Therefore, the shaft oil passage 313 is also sealed by oil.

[0139] Furthermore, since the oil pump stops in conjunction with the stop of the engine (driving source), after the supply of oil OL to the pressure-receiving chambers R1 and R2 via the in-shaft oil passage 313 stops, at least the oil OL in the pressure-receiving chamber R1 cannot be completely discharged (see Figure 4 (a)).

[0140] exist Figure 4 (a) shows a state in which the oil OL remains in a region on the lower side in the vertical direction with respect to the installation state of the continuously variable transmission 1.

[0141] exist Figure 4 In the state (a), when the vehicle equipped with the continuously variable transmission 1 is towed, the rotation input from the driving wheel side to the secondary pulley 4 is input to the primary pulley 3 via the belt V, and the primary pulley 3 rotates around the rotation axis X1 (refer to Figure 4 (b)).

[0142] Thus, the oil OL remaining in the pressure receiving chamber R1 moves toward the outer diameter side due to the centrifugal force generated by the rotation. Figure 4 As shown in (b), the oil OL in the pressure receiving chamber R1 is brought close to the inner periphery of the cylinder portion 323 .

[0143] When the traveling speed of the towed vehicle increases, the pressing force of the oil OL in the pressure receiving chamber R1 against the inner periphery of the cylinder portion 323 increases, and centrifugal oil pressure is generated in the pressure receiving chamber R1.

[0144] This centrifugal oil pressure acts in a direction (rightward in the figure) that moves the sliding pulley 32 toward the fixed pulley 31. That is, the centrifugal oil pressure acts to generate a thrust in a direction that narrows the groove width of the V-groove 33 of the primary pulley 3.

[0145] Thus, the difference (thrust difference) between the thrust generated on the secondary pulley 4 side by the urging force of the spring Sp and the thrust generated on the primary pulley 3 side by the centrifugal oil pressure decreases as the traveling speed of the towed vehicle increases.

[0146] Then, when the traveling speed of the towed vehicle exceeds a predetermined vehicle speed (threshold speed), the speed ratio of the speed change mechanism 2 changes from the lowest gear to the high gear side.

[0147] As a result, the rotation input from the primary pulley 3 to the forward / reverse switching mechanism 5 (planetary gear set 6) is smaller than that at the lowest gear.

[0148] In addition, the greater the speed of the towed vehicle, the greater the change in the speed ratio of the speed change mechanism 2 to the high gear side. Thus, the greater the speed of the towed vehicle, the less the rotation input from the primary pulley 3 to the forward / reverse switching mechanism 5 (planetary gear set 6) side.

[0149] Therefore, after the traveling speed of the towed vehicle exceeds a predetermined vehicle speed (threshold speed), the primary pulley 3 is prevented from reaching an extremely high rotation speed as in the conventional case.

[0150] This can appropriately prevent the durability of the bearing in contact with the primary pulley and the durability of the bearing on the planetary gear set 6 from being affected.

[0151] In the present embodiment, the following conditions are set so that the pulley portion 322 of the sliding pulley 32 is displaced toward the pulley portion 312 of the fixed pulley 31 when the traveling speed of the towed vehicle exceeds a predetermined vehicle speed (threshold speed).

[0152] (a) The volume of the pressure chamber R1, (b) The volume of the path (oil path) from the oil path 313 in the shaft to the pressure chamber R1, (c) The amount of oil remaining in the pressure chamber R1 (pulley pressure chamber) of the primary pulley 3 when the speed ratio of the speed change mechanism 2 is the lowest gear.

[0153] The amount of oil remaining in the pressure chamber R1 (pulley pressure chamber) of the primary pulley 3 when the speed ratio of the variator 2 is the lowest gear is calculated in advance and / or derived experimentally in consideration of the thrust generated by the spring Sp provided on the secondary pulley 4 .

[0154] Furthermore, in order to allow the amount of the derived oil to remain, the distance between the front plunger 35 of the primary pulley 3 and the pressure receiving surface 322 b of the slide pulley 32 is set when the speed ratio of the speed change mechanism is the lowest speed.

[0155] Furthermore, when the traveling speed of the towed vehicle is less than the predetermined speed, the above-mentioned conditions are set so that the speed ratio of the speed change mechanism 2 is maintained at the lowest gear ratio even if the oil stored in the pressure receiving chamber R1 of the primary pulley 3 generates a centrifugal oil pressure effect.

[0156] This is because the speed ratio does not need to be set to the high gear side while the rotation speed of the primary pulley 3 is a rotation speed that does not affect the durability of the bearing in contact with the primary pulley and the durability of the bearing on the planetary gear set 6 side.

[0157] Furthermore, in the present embodiment, when the speed ratio of the speed change mechanism 2 is changed from the lowest gear to the high gear side, the changed speed ratio is set to a speed ratio higher than the speed ratio of the lowest gear and lower than the gear ratio (mid-gear speed ratio) between the lowest gear ratio and the highest gear ratio. Specifically, it is a speed ratio greater than the speed ratio 1 (mid-gear speed ratio).

[0158] This is to facilitate the return to the lowest gear in consideration of restartability when the rotation speed of the drive wheel decreases. In addition, it is also to prevent the speed ratio from changing extremely greatly when the oil OL is not supplied to the pressure receiving chamber R1 (pulley pressure receiving chamber).

[0159] Furthermore, as the speed ratio becomes higher, the torque required to move the pulley in the vehicle on the towed side (towed vehicle) becomes larger.

[0160] Thus, a larger driving force (power) is required in the vehicle on the towing side, and the load on the vehicle on the towing side increases. Therefore, it is preferable not to make the load too large.

[0161] As described above, the continuously variable transmission 1 of this embodiment does not supply oil pressure from the oil pump driven by the engine to the pressure receiving chambers R1, R2, and R3 when the vehicle equipped with the continuously variable transmission 1 is being towed. This is because when being towed, the engine (drive source) is stopped and the oil pump driven by the engine is also stopped again.

[0162] Therefore, the oil OL remains in the pressure receiving chamber R1 of the primary pulley 3. When pulled, the centrifugal oil pressure generated by the oil OL remaining in the pressure receiving chamber R1 generates a thrust that shifts the speed ratio of the speed change mechanism 2 from the lowest gear to the high gear side.

[0163] This prevents the primary pulley 3 from rotating at an extremely high speed due to the rotation input from the drive wheel side, thereby not affecting the durability of the bearing supporting the primary pulley 3 and the durability of the bearing on the adjacent planetary gear set 6 side.

[0164] Here, when the vehicle is being towed, particularly when the ignition switch is off while the vehicle is being towed, the oil pump driven by the engine (driving source) is stopped, and the driving oil OL is not supplied to the speed change mechanism 2 .

[0165] Therefore, the thrust acting on the pressure receiving chambers R1 and R2 of the primary pulley 3 (the thrust for shifting the speed ratio of the speed change mechanism 2 toward the high gear side) is only the thrust due to the centrifugal oil pressure.

[0166] In other words, it can be said that the thrust due to the centrifugal oil pressure causes the speed ratio of the speed change mechanism 2 to be higher than the lowest speed.

[0167] As described above, the continuously variable transmission 1 of the present embodiment has the following structure.

[0168] (1) A continuously variable transmission 1 for a vehicle includes a speed change mechanism 2 having a primary pulley 3 , a secondary pulley 4 , and a belt V (an endless member) wound around the primary pulley 3 and the secondary pulley 4 .

[0169] The secondary pulley 4 is provided with a spring Sp (biasing member) that generates a biasing force in a direction to narrow the groove width of the V-shaped groove 43 of the secondary pulley 4 .

[0170] When the vehicle reaches a predetermined speed or higher while being towed, the centrifugal oil pressure of the oil stored in the pulley pressure receiving chamber of the primary pulley 3 causes the speed ratio of the speed change mechanism 2 to be higher than the lowest speed ratio.

[0171] If the dimensions of the primary pulley 3 are designed so that the amount of oil remaining in the pressure receiving chambers R1 and R2 (pulley pressure receiving chambers) of the primary pulley 3 becomes sufficient when the speed ratio of the speed change mechanism 2 is at the lowest gear, the following effects can be achieved.

[0172] (a) When the vehicle is being towed and the primary pulley 3 is rotating at a high speed, the remaining oil generates centrifugal force, thereby generating a centrifugal oil pressure action that acts as a thrust in a direction that narrows the groove width of the V-groove 33 of the primary pulley 3 .

[0173] As a result, the differential thrust between the primary pulley 3 and the secondary pulley 4 is reduced, and the speed ratio of the variator 2 is shifted to a higher speed side than the lowest speed.

[0174] Therefore, when the vehicle speed increases, the rotation speed of the primary pulley 3 decreases, so that it is possible to suppress the primary pulley 3 from reaching an extremely high rotation speed.

[0175] This prevents the primary pulley 3 from reaching an extremely high rotation speed, and thus can appropriately prevent the occurrence of a situation that affects the durability of the bearing in contact with the primary pulley 3 and the durability of the bearing on the planetary gear set 6 side.

[0176] The continuously variable transmission 1 of the present embodiment has the following structure.

[0177] (2) When the traveling speed of the vehicle when being towed is less than a specified vehicle speed (threshold speed), even when the centrifugal oil pressure of the oil stored in the pressure chamber R1 (pulley pressure chamber) of the primary pulley 3 is generated, the speed ratio of the transmission mechanism 2 is maintained at the lowest gear ratio.

[0178] When being towed, since there is no hydraulic pressure supplied, it is preferable not to change the speed ratio as much as possible. If the vehicle speed does not increase extremely, there is no concern that the primary pulley 3 will rotate at an extremely high speed, so the lowest gear state is maintained.

[0179] The continuously variable transmission 1 of the present embodiment has the following structure.

[0180] (3) When the vehicle reaches a speed above a specified speed while being towed, the centrifugal oil pressure of the oil OL stored in the pressure chamber R1 (pulley pressure chamber) of the primary pulley 3 causes the speed ratio of the transmission mechanism 2 to be higher than the lowest gear ratio and lower than the middle gear ratio (speed ratio = "1").

[0181] (a) When the rotation decreases, it is preferable to be able to easily return to the lowest gear in consideration of restartability. In addition, (b) it is not preferable to change the speed ratio extremely greatly in the state where the oil pressure is not supplied to the pulley pressure chamber. Therefore, the speed ratio is maintained at a speed ratio close to the lowest gear side, for example, at a speed ratio greater than the speed ratio = "1" (mid-gear speed ratio).

[0182] In addition, Figure 4 (a) illustrates a case where the oil OL remains in the pressure receiving chamber R1 and a part of the in-shaft oil passage 313 when the vehicle equipped with the continuously variable transmission 1 stops without supply of the oil OL from the hydraulic control circuit.

[0183] The form in which the oil OL remains is not limited to this form. For example, as long as the required centrifugal oil pressure effect can be generated, the oil OL may remain densely in the entire area of ​​the pressure receiving chamber R1 and the in-shaft oil passage 313.

[0184] Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above and can be appropriately modified within the scope of the technical concept of the invention.

Claims

1. A continuously variable transmission for a vehicle, comprising a transmission mechanism, the transmission mechanism comprising: a primary pulley, a secondary pulley, and an annular member wound around the primary pulley and the secondary pulley, characterized in that: The secondary pulley is provided with a force applying member, which generates a force in a direction of narrowing the groove width of the secondary pulley. After the supply of oil to the pressure-receiving chamber of the primary pulley is stopped, the pressure-receiving chamber of the primary pulley is sealed so that oil remains. After the supply of oil to the pressure chamber of the primary pulley is stopped, the amount of residual oil is set so that when the vehicle reaches a specified speed or above when being towed, the speed ratio of the transmission mechanism becomes higher than the lowest gear ratio and lower than the middle gear ratio through the centrifugal oil pressure of the oil stored in the pressure chamber of the primary pulley.

2. The continuously variable transmission for a vehicle according to claim 1, wherein: When the vehicle speed is less than the predetermined speed, the speed ratio of the speed change mechanism is maintained at the lowest speed ratio even when a centrifugal oil pressure action of the oil stored in the pressure receiving chamber of the primary pulley is generated.

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