JP2000130530A - Power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power transmission device improved in the transmission efficiency during forwarding and reversing, and increased in a reduction ratio in reverse stage. SOLUTION: When a forwarding/reversing switching device 17 is provided on the downstream side of a troidal type continuously variable transmission 15, a reduction ratio in reverse stage is a total reduction ratio represented by the product of a reduction ratio of the troidal type continuously variable transmission 15 and a reduction ratio of reverse stage gear 27 incorporated in the forwarding/reversing switching device 17 to obtain a larger reduction ratio. Since a friction multiple disk clutch 19 for interrupting power is interposed between the forwarding/reversing switching device 17 and a final transmission, inertia to be synchronized ends with the inertia of the friction multiple disk clutch 19 by disengaging the friction multiple disk clutch 19 when switching the device to forwarding or reversing, and thereby the transmission efficiency is improved compared to conventional power transmission device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission device having a continuously variable transmission, and more particularly to a power transmission device suitable for a vehicle.

[0002]

2. Description of the Related Art As a power transmission device having a continuously variable transmission, for example, a power transmission device having a belt-type continuously variable transmission and a power transmission device having a toroidal type continuously variable transmission have been known. I have. This type of power transmission device generally includes a fluid coupling connected to an output shaft of an engine, a continuously variable transmission connected to the fluid coupling, and switching the output from the continuously variable transmission in a forward direction or a reverse direction. And a forward / reverse switching device.

A power transmission device suitable for a vehicle includes a power transmission device having a toroidal type continuously variable transmission. Generally, a toroidal type continuously variable transmission rotates in a state of contacting an input disk and an output disk disposed opposite to each other, and both of the disks, and continuously changes the rotation of the input disk according to a tilt angle. And a transmission unit including a pair of power rollers for transmitting the power to the output disk. As a toroidal-type continuously variable transmission mounted on an automobile, a double-cavity toroidal-type continuously variable transmission in which two of the transmission units are arranged in tandem on the same shaft is generally used.

The outline of this double-cavity toroidal type continuously variable transmission will be described with reference to FIG.
The toroidal-type continuously variable transmission 15 shown in FIG. 4 has two sets of toroidal transmission units 1 and 2 arranged in parallel on the same axis. The toroidal transmission unit 1 faces an input shaft 13 to which torque output from an output shaft of the engine is input via a fluid coupling such as a torque converter 40, an input disk 4 driven by the input shaft 13, and an input disk 4. Output disks 5 connected to the output shafts 22 of the toroidal transmission units 1 and 2 and the input disks 4 and the output disks 5 and frictionally engaged with the toroidal curved surfaces of the two disks 4 and 5. A pair of power rollers 6 is provided. Like the toroidal transmission unit 1, the toroidal transmission unit 2 includes an input disk 7 driven by an input shaft 13,
An output disk 8 is disposed opposite to the input disk 7 and is connected to the connecting shaft 22, and a pair of power rollers 9 are in frictional contact with both disks.

In the toroidal type continuously variable transmission 15, the power rollers 6 and 9 respectively have their own rotation axis 1.
It is rotatable around zero and tiltable about a tilt axis 11 perpendicular to the rotation axis 10. By changing the tilt angle of the power rollers 6 and 9 at the same time, the rotation of the input disks 4 and 7 can be transmitted to the output disks 5 and 8 by changing the rotation in a stepless manner.

In the toroidal transmission section 1, the input disk 4 is connected to the main shaft 3 via a ball spline (not shown).
, And can move in the axial direction of the main shaft 3 and can rotate integrally with the main shaft 3. The main shaft 3 is arranged on the same axis as the input shaft 13. The distal end of the input shaft 13 is supported relative to the main shaft 3 by, for example, a bearing so as to be rotatable and immovable in the axial direction. On the back side of the input disk 4 opposite to the toroidal surface,
A cam mechanism 12 is provided. That is, the cam mechanism 12
Is constituted by a flange-like loading cam 18 provided at the tip of the input shaft 13 and a cam roller 16 interposed between the loading cam 18 and the rear surface of the input disk 4.

The input disk 7 of the toroidal transmission 2 is
It is attached to the other end of the main shaft 3 via a ball spline (not shown). Since the input disks 4 and 7 are respectively connected to the main shaft 3 via ball splines, they can slide in the thrust direction of the main shaft 3 and can rotate integrally with the main shaft 3. A part of the power from the input shaft 13 is transmitted to the input disk 4 via the loading cam 18, and the rest is transmitted to the input disk 7 via the main shaft 3 that rotates integrally with the input disk 4. At this time, when power is transmitted from the loading cam 18 to the input disk 4, a thrust corresponding to the transmitted torque is generated by the action of the cam roller 16. The thrust is transmitted to the input disk 4, the power roller 6, and the output disk 5 of the toroidal transmission unit 1 to exert a frictional engagement force between these rotating elements.
Further, the thrust is transmitted to the input disk 7, the power roller 9 and the output disk 8 of the toroidal transmission unit 2 via the main shaft 3 as a reaction of the cam roller 16, and a frictional engagement force is applied between these rotary elements.

The output disks 5, 8 are connected by spline fitting or the like to the cylindrical portions provided on both sides of the connecting shaft 22 so that the output disks 5, 8 can rotate integrally. The connecting shaft 22 is a hollow shaft fitted to the main shaft 3, and a sprocket 23 is integrally formed at an intermediate portion of the hollow shaft. The output disks 5, 8 are ball bearings (not shown) that support loads in the thrust direction and the radial direction via the connection shaft 22.
At the casing 25 of the transmission. Therefore,
The output disks 5 and 8 have their rear surfaces regulated axially by a casing 25.

A sprocket 23 is provided at an intermediate portion of the connecting shaft 22.
The rotation of the connecting shaft 22 is transmitted via a chain transmission 43 to a sprocket 44 attached to one end of a counter shaft 45 disposed parallel to the connecting shaft 22, and taken out from the counter shaft 45. It is.

A forward / reverse switching device 14 is disposed downstream of the toroidal type continuously variable transmission 15. That is, the forward / reverse switching device 14 includes the forward clutch 46 and the reverse clutch 38.
It is constituted by such as. The rotation of the counter shaft 45 is output to a transmission output shaft 49 via a forward clutch 46 and a reduction mechanism 48, and further transmitted to a differential device (not shown) that is a final reduction gear. The rotation of the input shaft 13 is controlled by a planetary gear mechanism 47 with a reverse clutch.
Can be transmitted to the transmission output shaft 49 in reverse. The output to the transmission output shaft 49 can be selected from forward rotation through the counter shaft 45 and reverse rotation through the planetary gear mechanism 47.

The forward / reverse switching device 14 will be described in detail.
At the other end of the counter shaft 45, a forward clutch 46, which is a friction multi-plate clutch, is provided. The output side of the forward clutch 46 is connected to a gear 30 rotatably fitted and supported on a counter shaft 45, and the gear 30 is connected to a transmission output shaft 49.
Gear 31 and the gear 30,
31 constitutes a speed reduction mechanism 48. Forward clutch 4
Numeral 6 is capable of switching the counter shaft 45 and the gear 30 to a slipping state or a torque transmitting state. Therefore, when the vehicle is moving forward, the forward clutch 46 is connected and the state is switched to the torque transmission state. When the vehicle is moving backward, the forward clutch 46 is disengaged and the state is switched to the idling state.

A planetary gear mechanism 47 is disposed between the main shaft 3 and the transmission output shaft 49. The planetary gear mechanism 47 includes a sun gear 34, a sun gear 3
4 and a ring gear 37 meshed with the pinion 36 and connected to the transmission output shaft 49.
Between the carrier 35 and the casing 25 of the transmission, a reverse clutch 38 including a friction multi-plate clutch for switching the carrier 35 to the idling state or the fixed state with respect to the casing 25 is incorporated. Therefore, when the vehicle is moving forward, the reverse clutch 38 is disengaged to switch the carrier 35 to the idling state. As a result, the rotation of the main shaft 3 is not transmitted to the transmission output shaft 49. When the vehicle is moving in reverse, the reverse clutch 38 is connected and the carrier 35 is switched to the fixed state, so that the rotation of the main shaft 3 is taken out from the transmission output shaft 49 as reverse rotation via the planetary gear mechanism 47.

[0013]

As described above, in the conventional power transmission device, the engine torque is output via the toroidal transmission units 1 and 2 when the vehicle is moving forward, and the engine torque is output when the vehicle is traveling backward. , 2 without passing through the planetary gear mechanism 47. And
Switching between forward and reverse is performed by connecting or disconnecting the forward clutch 46 and the reverse clutch 38. As described above, in the conventional power transmission device, two friction multi-plate clutches for intermittent power, that is, the forward clutch 46 and the reverse clutch 38 are required for switching between forward and backward traveling.

However, the conventional forward / reverse switching device 14
In either case, one of the two friction multi-plate clutches 38 and 46 is always idle when the vehicle is moving forward or backward, so that heat generation from the clutch plate due to the idle rotation cannot be avoided. Moreover, the inertia and drag torque of the friction multi-plate clutches 38 and 46 are large, and it is inevitable that the transmission efficiency of the friction multi-plate clutch is reduced due to idling. Further, the friction multi-plate clutch is expensive and disadvantageous. Further, since the reverse gear ratio is determined only by the gear ratio of the planetary gear mechanism 47, it is difficult to obtain a large gear ratio. For example, when the speed ratio of the toroidal transmission units 1 and 2 (the ratio of the input speed to the output speed) is 0.5 to 2 and the speed ratio of the forward speed reduction mechanism 48 is 2, the total speed ratio is 1 to 4. To match the speed ratio range of the forward gear, the gear ratio of the reverse gear is required to be about 4. However, in order to obtain the gear ratio of about 4 by the planetary gear mechanism 47, the diameter of the ring gear 37 must be considerably increased. There must be. However, there is a limit to increasing the diameter of the ring gear 37 due to the problem of interference with the casing 25 of the transmission.

[0015] The conventional power transmission device has the above-mentioned problems. Therefore, it is necessary to improve the transmission efficiency at the time of forward and reverse movements and to increase the reduction ratio of the reverse gear. Had become.

[0016]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems. In order to switch back and forth, a sleeve-type sliding clutch is used. By providing only one friction multi-plate clutch, the transmission efficiency is improved during forward and reverse travels, and the power intermittent clutch is used only at the time of forward / reverse switching to make it smaller than the starting clutch, and the reverse The reduction gear ratio of the reverse gear is increased by adopting the reduction gear train of the forward / reverse switching device instead of the planetary gear mechanism as the reduction gear of To provide an inexpensive power transmission device.

The present invention is configured as follows to achieve the above object. That is, the present invention provides a fluid coupling connected to an output shaft of an engine, a continuously variable transmission coupled to the fluid coupling, and a front-rear switching device for switching an output from the continuously variable transmission in a forward direction or a reverse direction. In a power transmission device provided with a forward / reverse switching device, the forward / reverse switching device is provided downstream of the continuously variable transmission, and an intermittent clutch including a friction multi-plate clutch is provided between the forward / reverse switching device and the final reduction gear. The present invention relates to a power transmission device interposed. Here, the final reduction gear means a differential device when this power transmission device is applied to a vehicle.

Since the forward / reverse switching device is provided on the downstream side of the continuously variable transmission, the reduction ratio at the reverse stage of the power transmission device is the same as the reduction ratio of the continuously variable transmission and the forward / reverse switching device. Since the total reduction ratio is obtained by multiplying the reduction ratio by the reduction ratio of the reduction mechanism, a large reduction ratio can be obtained. In addition, a forward / reverse switching device is provided downstream of the continuously variable transmission, and an intermittent clutch for intermittent power transmission consisting of a friction multi-plate clutch is interposed between the forward / reverse switching device and the final reduction gear. By disengaging the intermittent clutch when the device is switched to forward or reverse, only the inertia to be synchronized needs to be the inertia up to the intermittent clutch, so that the transmission efficiency is improved as compared with the related art.

In the above power transmission device, the forward / reverse switching device connects the rotation of the output shaft of the continuously variable transmission to the final reduction gear by switching a sleeve of a sleeve sliding clutch. This is a reduction gear train that outputs a forward or reverse rotation to the transmission output shaft. That is, when the sleeve is switched to the reverse gear, the rotation of the output shaft of the continuously variable transmission is transmitted to the transmission output shaft via the reduction gear train of the reverse gear. When the sleeve is switched to the forward gear, the rotation of the output shaft of the continuously variable transmission is transmitted to the transmission output shaft via the reduction gear train of the forward gear.

[0020] In the power transmission device, a one-way clutch is interposed between the main shaft of the continuously variable transmission and the transmission output shaft. When the rotation speed of the transmission output shaft is lower than the rotation speed of the main shaft, the one-way clutch is idle, and the rotation of the main shaft is transmitted to the transmission output shaft via the continuously variable transmission. However, when the rotation speed of the transmission output shaft becomes higher than the rotation speed of the main shaft, the one-way clutch is locked, that is, the main shaft and the transmission output shaft are directly connected, and power is transmitted from the main shaft through the continuously variable transmission. Without transmission to the transmission output shaft. Here, even if the engine is coasted, the locked state of the one-way clutch is continued, and the engine brake is activated.

In the above power transmission device, the continuously variable transmission is a toroidal type continuously variable transmission. The reduction ratio in the reverse gear of the power transmission device is a total reduction ratio obtained by multiplying the reduction ratio of the toroidal-type continuously variable transmission by the reduction ratio of the reduction mechanism of the forward / reverse switching device. Is obtained.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a power transmission device according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a first embodiment of a power transmission device according to the present invention. The toroidal type continuously variable transmission employed in this embodiment has the same structure as that of the conventional one shown in FIG. 4, so that the same members are given the same reference numerals and detailed description thereof will be omitted.

This power transmission device includes a torque converter 40, which is a fluid coupling connected to an output shaft of the engine, a toroidal-type continuously variable transmission 15 connected to the torque converter 40, and a toroidal-type continuously variable transmission 15. A forward / reverse switching device 17 for switching the output in the forward direction or the reverse direction is provided. Further, in this power transmission device, a forward / reverse switching device 17 is provided downstream of the toroidal-type continuously variable transmission 15, and a speed change between the forward / reverse switching device 17 and a differential device (not shown) serving as a final reduction gear is performed. Machine output shaft 4
In FIG. 9, an intermittent clutch for intermittent power at the time of forward / reverse switching, that is, a friction multi-plate clutch 19 is interposed.

The forward / reverse switching device 17 is operated by switching the sleeve 21 of the sleeve sliding clutch 20 to connect the two output disks 5 and 8 of the toroidal type continuously variable transmission 15 to each other. Continuously variable transmission 15
Is a reduction gear train that outputs the rotation of the output shaft (i.e., the output shaft) to the transmission output shaft 49 connected to the differential device by rotating forward or reverse. That is, the forward / reverse switching device 17 includes a counter shaft 45 arranged parallel to the main shaft 3 of the toroidal type continuously variable transmission 15 and a transmission output shaft arranged coaxially with the main shaft 3 and connected to the differential device. 49 and a spline gear 24 fixed to the tip of the transmission output shaft 49
, A forward gear 26 and a reverse gear 27 provided between the counter shaft 45 and the transmission output shaft 49, and an axially slidable forward gear 26 or a reverse gear 27.
And a sleeve 21 for connecting one of the two to the spline gear 24. The forward gear 26 is a gear 28 fixed to a counter shaft 45 and a gear 29 meshing with the gear 28. The forward gear 26 is rotatably attached to a transmission output shaft 49 and engages with the sleeve 21. The resulting dog teeth 32 are constituted by a two-stage gear train including a gear 29 provided integrally. The reverse gear 27 is integrally provided with an input gear 33 fixed to a counter shaft 45 and a dog tooth 39 which is rotatably attached to a transmission output shaft 49 and can be engaged with the sleeve 21. And a three-stage gear train including an output gear 41 and an intermediate gear 42 meshing with both the input gear 33 and the output gear 41. The sleeve 21 moves the spline gear 2 when moving forward.
4 and the dog teeth 32 of the gear 29 are connected, and the spline gear 24 and the dog teeth 39 of the output gear 41 are connected during reverse travel.

The rotation direction of the counter shaft 45 is opposite to the rotation direction of the input shaft 13 of the toroidal type continuously variable transmission 15.
At the time of forward movement, the sleeve 21 meshes with the dog teeth 32 and the spline gear 24 provided on the transmission output shaft 49, and the rotation of the counter shaft 45 is reversed and output to the transmission output shaft 49. Therefore, during forward movement, the transmission output shaft 49 rotates in the same direction as the rotation direction of the input shaft 13.
In reverse, the sleeve 21 meshes with the dog teeth 39 and the spline gear 24 provided on the transmission output shaft 49,
A rotation in the same direction as the rotation of the counter shaft 45 is output to the transmission output shaft 49. Therefore, when the vehicle is traveling backward, the transmission output shaft 49 rotates in the direction opposite to the rotation direction of the input shaft 13.

When the forward / reverse switching device 17 is switched to the forward stage, the frictional multi-plate clutch 19 for intermittent power is temporarily disengaged, the sleeve 21 is shifted rightward in FIG. 19 is connected. When switching to the reverse gear, the friction multiple disc clutch 1
9, the sleeve 21 is shifted leftward in FIG. 1, and then the friction multiple disc clutch 19 is connected again.

The rotation of the engine is controlled by the torque converter 40.
Through the toroidal-type continuously variable transmission 15 and through the toroidal transmission units 1 and 2 regardless of whether the vehicle is moving forward or backward, the connecting shaft 22, the chain transmission 43, and the counter shaft 45. , Via the forward / reverse switching device 17,
Output to transmission output shaft 49. Therefore, the reduction ratio of the reverse gear in the conventional gear is the planetary gear mechanism 47 (FIG. 4).
In the power transmission device of this embodiment, the reduction ratio of the reverse gear is increased by operating the toroidal-type continuously variable transmission 15 in comparison with the reduction ratio of As a result, the reverse gear 27, which is a three-stage gear train,
, A large reduction ratio can be realized as a whole. Conversely, since this power transmission device can obtain a large reduction ratio, a small reverse gear 27 can be employed, and the size of the device can be reduced as a whole.

In this power transmission device, a forward / reverse switching device 17 is provided downstream of the toroidal-type continuously variable transmission 15.
One friction multi-plate clutch 19 for intermittent power at the time of forward / reverse switching is provided further downstream of the forward / backward switching device 17, and the forward / backward switching is performed by the sleeve 2 of the forward / backward switching device 17.
1 is shifted, the inertia to be synchronized at the time of gear shifting is the friction multiple disc clutch 1
Since only the inertia up to 9 is required, the inertia to be synchronized at the time of shifting can be reduced. Therefore, this power transmission device has improved transmission efficiency as compared with the conventional power transmission device shown in FIG.

Next, another embodiment of the power transmission device of the present invention will be described. FIG. 2 is a schematic diagram showing a second embodiment of the power transmission device according to the present invention. The power transmission device of FIG. 2 is different from the power transmission device of FIG. 1 in the structure and arrangement of the forward / reverse switching device. That is, in the first embodiment, the sleeve 21 is disposed on the transmission output shaft 49 side, whereas in the second embodiment, the sleeve 21 is disposed on the counter shaft 45 side. There is no particular difference in other structures. In addition, the forward and backward switching has basically the same operation and effect as the first embodiment.

The forward / reverse switching device 50 includes a forward gear 51, a reverse gear 52, and a sleeve sliding clutch 53. The forward gear 51 is a gear 54 fixed to the transmission output shaft 49, and a gear 55 meshing with the gear 54. The forward gear 51 is rotatably attached to the counter shaft 45 and can be engaged with a sleeve 56. The teeth 57 are constituted by a two-stage gear train including a gear 55 provided integrally. The reverse gear 52 has an output gear 58 fixed to the tip of a transmission output shaft 49 and a dog tooth 59 which is attached to the counter shaft 45 so as to be rotatable relative to the counter shaft 45 and can engage with the sleeve 56. Input gear 60 provided in the
It is constituted by a three-stage gear train including an intermediate gear 61 meshing with both the input gear 60 and the output gear 58.
Further, a spline gear 62 is attached to the counter shaft 45, and the spline gear 62 is arranged between a dog tooth 57 of the gear 55 and a dog tooth 59 of the input gear 60. The sleeve 56 connects the spline gear 62 and the dog teeth 57 of the gear 55 when moving forward, and connects the spline gear 62 and the dog teeth 59 of the input gear 60 when moving backward.

Next, still another embodiment of the power transmission device of the present invention will be described. FIG. 3 is a schematic diagram showing a third embodiment of the power transmission device according to the present invention. The power transmission device of this embodiment is obtained by adding a one-way clutch to the power transmission device of the second embodiment shown in FIG. The one-way clutch 63 is connected to the main shaft 3 of the toroidal type continuously variable transmission 15.
And a transmission output shaft 49. The one-way clutch 63 idles when the rotation speed of the transmission output shaft 49 is lower than that of the main shaft 3 and locks when the rotation speed of the transmission output shaft 49 is going to be higher than that of the main shaft 3. Therefore, when the rotation speed of the transmission output shaft 49 is lower than that of the main shaft 3, the rotation of the main shaft 3 is controlled by the toroidal transmission units 1 and 2 and the forward gear 5 of the forward / reverse switching device 50.
1 to the transmission output shaft 49. However,
When the rotational speed of the transmission output shaft 49 becomes higher than that of the main shaft 3, the one-way clutch 63 is locked, and the main shaft 3 and the transmission output shaft 49 are directly connected. The power is transmitted directly to the transmission output shaft 49 without passing through the units 1 and 2.

To explain this point in more detail, in the forward gear, the transmission is shifted by the toroidal transmission units 1 and 2, the power is transmitted to the counter shaft 45 via the chain transmission 43, the speed is reduced by the forward gear 51, and the transmission Power is transmitted to the output shaft 49. At this time, when the overall speed ratio is slightly larger than the speed ratio (maximum speed increase ratio) when the speed is increased to a maximum by the toroidal speed change units 1 and 2, the main shaft 3 and the transmission output shaft 49 are the same. So that the rotation speed
The gear ratio of the forward gear 51 is determined. That is, the design is made such that (the maximum speed increase ratio of the toroidal transmission portions 1 and 2) × (the gear ratio of the forward gear 51) is slightly smaller than 1. With this design, in the forward gear, the rotation of the main shaft 3 is higher than the rotation of the transmission output shaft 49 from the start to one step before the maximum speed increase, so that the one-way clutch 63 is idle and the power is toroidal transmission. The transmission is transmitted to the transmission output shaft 49 via the sections 1 and 2. Further, the gear ratio of the toroidal transmission units 1 and 2 is further changed to the speed increasing side, and when (the maximum gear ratio of the toroidal transmission unit) × (the gear ratio of the forward gear) becomes slightly smaller than 1, The one-way clutch 63 is locked, and the power is output to the transmission output shaft 49 in a directly connected state without passing through the toroidal transmission units 1 and 2. Here, even if the engine is coasted, the one-way clutch 63 continues to be in the locked state, and the engine brake operates.

[0033]

The power transmission device according to the present invention is configured as described above, and has the following effects.
That is, since an inexpensive sleeve sliding clutch is used as the forward / reverse switching device instead of the expensive friction multi-plate clutch, the overall structure of the power transmission device can be simplified and the cost can be reduced.

Further, since the intermittent friction multi-plate clutch is interposed between the forward / reverse switching device and the final reduction gear, the friction multi-plate clutch is always connected during operation except during forward / reverse switching. In addition, it is possible to prevent the transmission efficiency from decreasing due to the heat generated by the clutch plate. In addition, when switching between forward and reverse, the on-off clutch is temporarily disengaged and then the sleeve is switched, so that the inertia to be synchronized at the time of shifting is only the inertia up to the on-off clutch and can be reduced. Therefore, the transmission efficiency of this power transmission device is improved as compared with the conventional one. Further, the power intermittent clutch is used only at the time of switching between forward and reverse, so that it is possible to reduce the size as compared with the starting clutch.

Further, in this power transmission device, since the planetary gear mechanism is not used in the reverse gear,
The rotation of the engine is transmitted to the final reduction gear via the reduction gear train of the forward / reverse switching device via the toroidal transmission unit. Therefore, the reduction ratio of the reverse gear is a reduction gear ratio obtained by multiplying the reduction gear ratio of the toroidal transmission portion and the reduction gear ratio of the reduction gear train, so that a large reduction gear ratio can be obtained in the reverse gear.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a first embodiment of a power transmission device according to the present invention.

FIG. 2 is a schematic diagram showing a second embodiment of the power transmission device according to the present invention.

FIG. 3 is a schematic view showing a third embodiment of the power transmission device according to the present invention.

FIG. 4 is a schematic diagram showing an example of a conventional power transmission device.

[Explanation of symbols]

 15 Toroidal type continuously variable transmission (continuously variable transmission) 17, 50 Forward / reverse switching device 19 Friction multi-plate clutch (intermittent clutch) 20, 53 Sleeve sliding type clutch 21, 56 Sleeve 22 Output shaft 26, 51 Forward gear (Reduction gear train) 27, 52 reverse gear (reduction gear train) 40 torque converter (fluid coupling) 49 transmission output shaft 63 one-way clutch

Claims (4)

[Claims] 1. A fluid coupling connected to an output shaft of an engine, a continuously variable transmission coupled to the fluid coupling, and a forward / reverse drive for switching an output from the continuously variable transmission in a forward direction or a reverse direction. In a power transmission device provided with a switching device, the forward / reverse switching device is provided downstream of the continuously variable transmission, and an on / off clutch for power disconnection is interposed between the forward / reverse switching device and the final reduction gear. A power transmission device characterized by the above-mentioned. 2. The forward / reverse switching device switches the sleeve of a sleeve-slidable clutch to rotate the output shaft of the continuously variable transmission to a transmission output shaft connected to the final reduction gear. The power transmission device according to claim 1, wherein the power transmission device is a reduction gear train that outputs the rotation in a forward or reverse direction. 3. The power transmission device according to claim 1, wherein a one-way clutch is interposed between a main shaft of the continuously variable transmission and the transmission output shaft. 4. The continuously variable transmission according to claim 1, wherein the continuously variable transmission is a toroidal type continuously variable transmission.
A power transmission device according to the item.