Continuously variable transmission

Abstract

Provided is a continuously variable transmission with which it is possible to lubricate a gear transmission device without using traction oil. This continuously variable transmission includes: a variator including an input disk having a curved raceway surface and rotating integrally with an input shaft, an output disk having a raceway surface facing the raceway surface, and a roller pressed against the two raceway surfaces; an element to which torque of the output disk is input; a gear transmission device to which torque of the element is input; a first case housing the variator and the element; and a second case housing the first case and the gear transmission device.

Description

continuously variable transmission

[0001] The present invention relates to a continuously variable transmission including a variator and a gear transmission.

[0002] Prior art relating to a continuously variable transmission equipped with a variator including an input disc having a curved raceway surface that rotates integrally with the input shaft, an output disc having a curved raceway surface, and a roller pressed between the two raceway surfaces, and a gear transmission to which the torque of the output disc is input, is disclosed in Patent Document 1. The variator uses a fluid called traction oil to create an oil film between the roller and the raceway surface, and transmits torque via the oil film.

[0003] JP 2008-38902 A

[0004] In the prior art, the variator and gear transmission are housed in a single case, so if the gear transmission shares the same traction oil as the variator, a large amount of traction oil is required. Furthermore, when the gears in the gear transmission transmit torque, a film of traction oil is formed, which can increase losses due to frictional resistance.

[0005] The present invention has been made to solve this problem, and has as its object to provide a continuously variable transmission that can lubricate the gear transmission without using traction oil.

[0006] A first aspect for achieving this object comprises a variator including an input disc having a curved raceway surface and rotating integrally with the input shaft, an output disc having a raceway surface opposite the raceway surface, and a roller pressed against the two raceway surfaces, an element to which the torque of the output disc is input, a gear transmission to which the torque of the element is input, a first case that houses the variator and the element, and a second case that houses the first case and the gear transmission.

[0007] In the second aspect, in the first aspect, the first case is fixed to the second case.

[0008] In a third aspect, the device according to the first or second aspect further includes a first shaft that rotates integrally with the element, and a bearing that supports the first shaft, the bearing being fixed to the first case.

[0009] In a fourth aspect, in any one of the first to third aspects, the gear transmission includes a planetary transmission, and the planetary transmission is arranged on a second shaft arranged parallel to the first shaft, and receives torque from the element.

[0010] A fifth aspect is the fourth aspect, further comprising a clutch disposed on the second shaft to limit relative rotation between the moving body of the planetary transmission and the second shaft, the clutch being housed in the second case.

[0011] According to the continuously variable transmission of the present invention, the variator and an element to which torque from the output disk of the variator is input are housed in a first case, and the first case and the gear transmission are housed in a second case. Since the first case contains traction oil and the second case contains a fluid suitable for lubricating the gear transmission, the gear transmission can be lubricated without using traction oil.

[0012] 1 is a skeleton diagram of a continuously variable transmission according to an embodiment.

[0013] A preferred embodiment of the present invention will now be described with reference to the accompanying drawings. Fig. 1 is a skeleton diagram of a continuously variable transmission 10 according to one embodiment. The continuously variable transmission 10 includes a toroidal type continuously variable transmission (variator) 11 and a gear transmission 30.

[0014] The variator 11 is disposed on an input shaft 14 to which torque from a crankshaft of an engine 12 is transmitted via a clutch 13. The variator 11 includes input discs 15 and 16 that rotate integrally with the input shaft 14, an output disc 17 that is positioned between the input discs 15 and 16 and rotatably disposed on the input shaft 14, and rollers 18 and 19 that are respectively disposed between the input discs 15 and 16 and the output disc 17. In this embodiment, the variator 11 is a double-cavity half-toroidal transmission.

[0015] The variator 11 is equipped with a pressure device (not shown). The pressure device includes, for example, a drum that rotates integrally with the input disc 15. The input discs 15, 16 are attached to the input shaft 14 so as to be axially movable. The drum generates a pressing force (hydraulic pressure) proportional to torque, and elastically presses the input disc 15 toward the output disc 17. The input disc 16 receives the thrust load, and the output disc 17 transmits the torque via rollers 18, 19 disposed between the input discs 15, 16 and the output disc 17. The pressure device is not limited to a hydraulic mechanism that generates a pressing force proportional to torque. For example, it is of course possible to use a mechanical cam mechanism as the pressure device.

[0016] Curved raceway surface 20 on input disk 15 faces curved raceway surface 21 on output disk 17. Curved raceway surface 22 on input disk 16 faces curved raceway surface 23 on output disk 17. Rollers 18 and 19 are each rotatably supported by a carriage (not shown). Roller 18 is pressed against raceway surfaces 20 and 21 by a carriage with a caster angle, and roller 19 is pressed against raceway surfaces 22 and 23 by a carriage with a caster angle.

[0017] The input shaft 14, the first shaft 24, and the second shaft 25 are arranged parallel to each other on different axes. A driving element 26 coupled to the output disk 17 transmits torque to a driven element 27 supported on the first shaft 24. In this embodiment, the driving element 26 and the driven element 27 are gears, and the driving element 26 is always in mesh with the driven element 27, and torque is transmitted by the gear meshing.

[0018] The driving element 26 and the driven element 27 are not limited to gears and may be other means for transmitting torque. Examples of other means for transmitting torque include a sprocket that transmits torque by a chain wound around the driving element 26 and the driven element 27, a pulley that transmits torque by a belt wound around the driving element 26 and the driven element 27, and a roller that transmits torque by friction between the driving element 26 and the driven element 27.

[0019] The variator 11, driving element 26, and driven element 27 are housed in a first case 28. If a chain or belt is interposed between the driving element 26 and the driven element 27, the chain or belt is also housed in the first case 28. Traction oil is housed in the first case 28. The traction oil forms an oil film between the roller 18 and the raceway surfaces 20 and 21, and between the roller 19 and the raceway surfaces 22 and 23, and the shear resistance of the oil film appears as a traction force that pulls the input discs 15 and 16, the rollers 18 and 19, and the output disc 17 in that order, thereby transmitting torque.

[0020] The input shaft 14 and the first shaft 24 pass through a first case 28 via an oil seal. In this embodiment, the driven element 27 is coupled to the first shaft 24, and the first shaft 24 rotates integrally with the driven element 27. The first shaft 24 is rotatably supported by bearings 29 fixed to the first case 28, so that the bearings 29 can be arranged in positions suitable for arranging the bearings 29. The bearings 29 are arranged symmetrically on both sides of the driven element 27.

[0021] The gear transmission 30 is a device for amplifying the torque of the driven element 27. The gear transmission 30 includes a first gear 31 connected to the input shaft 14, a second gear 32 rotatably disposed on the second shaft 25 and meshing with the first gear 31, a third gear 33 connected to the first shaft 24, a fourth gear 34 rotatably disposed on the second shaft 25 and meshing with the third gear 33, and a first planetary transmission 35 connected to the second gear 32 and the fourth gear 34. The first planetary transmission 35 is disposed on the second shaft 25.

[0022] The gear transmission 30 further includes a fifth gear 42 coupled to the input shaft 14, a sixth gear 43 rotatably disposed on the second shaft 25 and meshing with the fifth gear 42, a seventh gear 44 coupled to the first shaft 24, an eighth gear 45 rotatably disposed on the second shaft 25 and meshing with the seventh gear 44, and a second planetary transmission 46 coupled to the sixth gear 43 and the eighth gear 45. The second planetary transmission 46 is also disposed on the second shaft 25.

[0023] The fifth gear 42 is disposed on the input shaft 14 on the opposite side of the first case 28 from the first gear 31. The seventh gear 44 is disposed on the first shaft 24 on the opposite side of the first case 28 from the third gear 33. Because the third gear 33 is disposed between the first gear 31 and the first case 28, and the seventh gear 44 is disposed between the fifth gear 42 and the first case 28, the space occupied by the first gear 31, the third gear 33, the fifth gear 42, the seventh gear 44, and the first case 28 can be reduced.

[0024] The first planetary transmission 35 is a high-speed transmission, and the second planetary transmission 46 is a low-speed transmission. The first planetary transmission 35 and the second planetary transmission 46 have different gear ratios. The first planetary transmission 35 includes a sun gear 36 connected to the second gear 32, a ring gear 37 connected to the fourth gear 34, a pinion 38 meshing with the sun gear 36 and the ring gear 37, and a carrier 39 that rotatably supports the pinion 38. A cylindrical third case 40 connected to the carrier 39 is rotatably disposed on the second shaft 25. A clutch 41 disposed in the third case 40 has the function of transmitting and interrupting torque from the third case 40 to the second shaft 25 between the third case 40 and the second shaft 25.

[0025] The second planetary transmission 46 includes a sun gear 47 connected to the sixth gear 43, a ring gear 48 connected to the eighth gear 45, a pinion 49 meshing with the sun gear 47 and the ring gear 48, and a carrier 50 that rotatably supports the pinion 49. A cylindrical third case 51 connected to the carrier 50 is rotatably disposed on the second shaft 25. A clutch 52 disposed in the third case 51 has the function of transmitting and interrupting torque from the third case 51 to the second shaft 25 between the third case 51 and the second shaft 25.

[0026] When the clutch 41 is engaged and the clutch 52 is disengaged, torque is transmitted from the third case 40 to the second shaft 25, and when the clutch 41 is disengaged and the clutch 52 is engaged, torque is transmitted from the third case 51 to the second shaft 25. In this embodiment, the clutches 41 and 52 are friction clutches. Because the clutches 41 and 52 are disposed in the space on the second shaft 25 created between the first planetary transmission 35 and the second planetary transmission 46, the overall length of the second shaft 25 can be shortened.

[0027] A reversing mechanism 53 is connected to the second shaft 25. The reversing mechanism 53 reverses the direction of rotation of the second shaft 25 and transmits the rotation. The reversing mechanism 53 includes a drum 54 connected to the second shaft 25, a first hub 55 and a second hub 56 arranged axially next to each other and inside the drum 54, a first clutch 57 arranged between the first hub 55 and the drum 54, and a second clutch 58 arranged between the second hub 56 and the drum 54.

[0028] A third shaft 59, arranged coaxially with the second shaft 25, is connected to the first hub 55, and a ninth gear 60, arranged rotatably on the third shaft 59, is connected to the second hub 56. A tenth gear 61, which meshes with the ninth gear 60, is connected to the fourth shaft 62. The first clutch 57 and the second clutch 58 function by mechanical actuation, electromagnetic actuation, hydraulic actuation, pneumatic actuation, or the like. When the first clutch 57 is engaged and the second clutch 58 is disengaged, the torque of the second shaft 25 is transmitted to the third shaft 59, and when the first clutch 57 is disengaged and the second clutch 58 is engaged, the torque of the second shaft 25 is reversed and transmitted to the fourth shaft 62.

[0029] The first case 28, the gear transmission 30, the clutches 41 and 52, and the reversing mechanism 53 are housed in a second case 63. The input shaft 14, the third shaft 59, and the fourth shaft 62 pass through the second case 63 via oil seals. The first case 28 is fixed to the second case 63. Since the first case 28 can be prevented from colliding with the variator 11 or the gear transmission 30, damage to the variator 11 or the gear transmission 30 and the generation of abnormal noise can be reduced. Furthermore, force based on the mechanical energy of the first case 28 generated by vibrations or the like can be prevented from being applied to the input shaft 14 passing through the first case 28.

[0030] The second case 63 contains a fluid (lubricating oil) suitable for lubricating the gear transmission 30, the clutches 41, 52, and the reversing mechanism 53. The lubricating oil is a different fluid from the traction oil contained in the first case 28, and an example of the lubricating oil is a fluid having a μ smaller than that of the traction oil (the ratio T / N of the tangential force T to the pressing force N). Because the traction oil is contained in the first case 28 and the lubricating oil is contained in the second case 63, the gear transmission 30 can be lubricated without using traction oil. Compared to when the gear transmission 30 shares traction oil with the variator 11, the amount of traction oil can be reduced, and the lubricating oil can also reduce the frictional resistance of the gear transmission 30.

[0031] When a continuously variable transmission 10 is mounted on a vehicle (not shown) such as an automobile or agricultural machine and an engine 12 drives the wheels, clutch 13 is engaged when starting (moving forward) the vehicle, and clutch 52 and first clutch 57 are engaged, while clutch 41 and second clutch 58 are disengaged. In continuously variable transmission 10, torque output by variator 11 is amplified by second planetary transmission 46 for low speeds and output from third shaft 59. This allows the vehicle to start and accelerate continuously without interruption of torque or gear change shock.

[0032] As the vehicle speed increases, clutch 41 is engaged and clutch 52 is disengaged. In continuously variable transmission 10, the torque output by variator 11 is amplified by first planetary transmission 35 for high speeds and output from third shaft 59. Because continuously variable transmission 10 is equipped with first planetary transmission 35 and second planetary transmission 46, transmission efficiency can be improved by switching from second planetary transmission 46 to first planetary transmission 35 according to vehicle speed.

[0033] When the vehicle is traveling at high speeds, the continuously variable transmission 10 distributes the torque of the input shaft 14 to the variator 11 and the first planetary transmission 35, so the torque transmitted by the variator 11 can be reduced compared to when the variator 11 transmits all of the torque of the input shaft 14. Since the energy loss generated in the variator 11 can be reduced, the size and weight of the variator 11 can be reduced and the transmission efficiency of the continuously variable transmission 10 can be improved.

[0034] When starting the vehicle (reverse), the clutch 13 is engaged, and the clutch 52 and second clutch 58 are engaged, while the clutch 41 and first clutch 57 are disengaged. In the continuously variable transmission 10, the torque output by the variator 11 is amplified by the low-speed second planetary transmission 46 and output from the fourth shaft 62. This allows the vehicle to start and accelerate. When the reversing mechanism 53 is switched while the vehicle is stopped, the mechanism can be simplified and robustness can be improved compared to when the reversing mechanism 53 is switched while the vehicle is moving.

[0035] The present invention has been described above based on an embodiment, but the present invention is not limited to this embodiment in any way, and it can be easily inferred that various improvements and modifications are possible within the scope of the present invention without departing from the spirit of the present invention.

[0036] In the embodiment, a double-cavity half-toroidal transmission is used as the variator 11, but this is not necessarily limited to this. Naturally, a single-cavity variator or a full-toroidal variator can also be used as the variator 11.

[0037] In the embodiment, the case where the driven element 27 is coupled to the first shaft 24 and rotates integrally with the first shaft 24 has been described, but this is not necessarily limited to this. It is of course possible to rotatably arrange the driven element 27 on the first shaft 24, provide two elements coupled to the driven element 27, and rotatably arrange the elements on the first shaft 24. In this case, when torque is transmitted to the driven element 27, one of the elements provided on the first shaft 24 transmits the torque to the fourth gear 34, and the other element transmits the torque to the eighth gear 45.

[0038] In the embodiment, the first planetary transmission 35 and the second planetary transmission 46 are planetary gear units including sun gears 36, 47, ring gears 37, 48, and pinions 38, 49, but this is not necessarily limited to this. It is of course possible to use planetary roller units that transmit power using traction instead of planetary gear units. Using a planetary roller unit can reduce vibration and noise and eliminate backlash.

[0039] In the embodiment, the first planetary transmission 35 and the second planetary transmission 46 are each provided with a single planetary gear train, but this is not necessarily limited to this. It is of course possible to use a compound planetary gear train, which is a combination of multiple single planetary gear trains, in the first planetary transmission 35 or the second planetary transmission 46.

[0040] In the embodiment, the sun gear 36 of the first planetary transmission 35 is coupled to the second gear 32, the ring gear 37 is coupled to the fourth gear 34, and the carrier 39 is coupled to the second shaft 25, but this is not necessarily limited to this. Also, in the embodiment, the sun gear 47 of the second planetary transmission 46 is coupled to the sixth gear 43, the ring gear 48 is coupled to the eighth gear 45, and the carrier 50 is coupled to the second shaft 25, but this is not necessarily limited to this. As long as low-speed and high-speed transmissions can be configured, this is not necessarily limited to the embodiment.

[0041] REFERENCE SIGNS LIST 10 Continuously variable transmission 11 Variator 14 Input shaft 15 Input disc 17 Output disc 18 Roller 20, 21 Raceway surface 24 First shaft 25 Second shaft 27 Driven element (element) 28 First case 29 Bearing 30 Gear transmission 35 First planetary transmission (planetary transmission) 39 Carrier (moving body) 41 Clutch 46 Second planetary transmission (planetary transmission) 50 Carrier (moving body) 52 Clutch 63 Second case

Claims

1. A continuously variable transmission comprising: a variator including an input disc having a curved raceway surface and rotating integrally with an input shaft; an output disc having a raceway surface opposing the raceway surface; and rollers pressed against the two raceway surfaces; an element to which the torque of the output disc is input; a gear transmission to which the torque of the element is input; a first case that houses the variator and the element; and a second case that houses the first case and the gear transmission.

2. A continuously variable transmission according to claim 1, wherein said first case is fixed to said second case.

3. A continuously variable transmission according to claim 1 or 2, further comprising: a first shaft that rotates integrally with said element; and a bearing that supports said first shaft, said bearing being fixed to said first case.

4. The continuously variable transmission according to claim 3, wherein the gear transmission includes a planetary transmission, the planetary transmission being disposed on a second shaft disposed parallel to the first shaft and receiving torque from the element.

5. A continuously variable transmission according to claim 4, further comprising a clutch disposed on said second shaft for limiting relative rotation between said planetary transmission moving body and said second shaft, said clutch being housed in said second case.

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