JP3009502B2 - Vehicle power transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a first power transmission path including a speed reducer and a second power transmission path including a continuously variable transmission. The present invention relates to a power transmission device for a vehicle in which a power transmission path is switched by switching a friction element.

[0002]

2. Description of the Related Art Conventionally, as a power transmission device for transmitting an engine output, a first power transmission path including a reduction gear (one or more stepped transmission mechanisms) as disclosed in Japanese Patent Application Laid-Open No. 2-240444. And a second power transmission path including a continuously variable transmission, and a clutch (lock-up clutch) for switching the power transmission path. The first and second clutches are engaged and disengaged in accordance with the operation state. And a second power transmission path.

According to this device, a relatively large speed ratio can be obtained in the first power transmission path, and a speed ratio that can be continuously changed on the side of the relatively small speed ratio can be obtained in the second power transmission path. For example, by transmitting the engine output through the first power transmission path in the low vehicle speed operation area and transmitting the engine output through the second power transmission path in the high vehicle speed operation area, It is possible to set and adjust an appropriate gear ratio in the operating region.

[0004]

However, in this type of apparatus, when the power transmission path is rapidly switched by the operation of the clutch, a considerable shock occurs. In order to reduce the shock at the time of switching the power transmission path, it is desirable to reduce the operating speed of the clutch. However, in this case, when the rotational speed difference between the clutch input side and the output side is large, wear tends to occur. In addition, problems such as a decrease in responsiveness during acceleration or the like where the input torque to the friction element is large occur.

In this device, the maximum speed ratio of the continuously variable transmission in the second power transmission path is set to the minimum speed of the first power transmission path in order to suppress a sudden change in the speed ratio when the power transmission path is switched. It is conceivable to provide a region where the speed ratio fluctuation ranges of both transmission paths overlap by setting the speed ratio to be larger than the speed ratio, but this alone cannot sufficiently solve the problem such as the shock.

An object of the present invention is to solve the above-mentioned problem by appropriately adjusting a power transmission path switching operation to prevent abrasion of a friction element while reducing a shock and satisfy acceleration response. It is an object of the present invention to provide a power transmission device for a vehicle that can be used.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a first power transmission path for transmitting an engine output to a wheel via a reduction gear, and an engine output via a continuously variable transmission. A second power transmission path for transmitting power to the wheels;
A power transmission path switching friction element for switching between the two paths, wherein the friction element is switched in accordance with an operating state. Rotation speed adjustment means for adjusting the rotation speed and the output side rotation speed so as to substantially coincide with each other; torque detection means for detecting an input torque at the time of the switching operation of the friction element; and Operating speed control means for controlling the switching operation speed to be lower as the input torque becomes smaller.

In this configuration, it is preferable that the first power transmission path passes through the torque converter and the second power transmission path bypasses the torque converter.

Further, by setting the maximum speed ratio of the continuously variable transmission on the second power transmission path to be larger than the minimum speed ratio of the first power transmission path, a range where the speed ratio fluctuation ranges of both transmission paths overlap with each other. Preferably, the rotational speed adjusting means is configured to adjust the speed ratio of the continuously variable transmission within the overlap region.

[0010]

According to the apparatus of the present invention, when the input torque is small, the switching operation speed of the friction element is reduced, so that the shock accompanying the power transmission path switching is reduced.
In addition, since the input-side rotational speed and the output-side rotational speed are adjusted to be substantially equal to each other, abrasion due to slippage during the switching operation of the clutch can be avoided. On the other hand, when the input torque is large, the acceleration responsiveness is satisfied by increasing the switching operation speed of the friction element.

[0011]

An embodiment of the present invention will be described with reference to the drawings.
1 and 2 show a transmission path component of a power transmission device according to an embodiment of the present invention. In these figures, the power transmission device connected to the output side of the engine 1 is:
First and second power transmission paths 3 and 4 switched by path switching clutch (power transmission path switching friction element) 2
have. The first power transmission path 3 is for transmitting the engine output to the wheel side via a speed reduction device 7, and in this embodiment, is transmitted via a torque converter 5 and a forward / reverse switching device 6.
Power is transmitted to the wheel side via the speed reducer 7. The second power transmission path 4 transmits the engine output to the wheels via the continuously variable transmission 8.

The torque converter 5 has an input shaft 5
a inside the pump cover 11 connected to the
1 includes a pump impeller 12 integral with the turbine impeller 1, a turbine liner 13 facing the pump impeller 12, and a stator 14 mounted on a hollow fixed shaft 15 via a one-way clutch 16 in a state located therebetween. The input shaft 5a is connected to an engine output shaft, and the turbine liner 13 is connected to a turbine shaft 17 as an output shaft. The space inside the pump cover 11 is filled with oil as a working fluid. A hollow rotary shaft 18 is connected to the pump impeller 12, and an oil pump 50 is attached to the rear end of the shaft 18.

The speed reducer 7 includes a turbine shaft 17
And two planetary gear mechanisms 20 and 21 for backward and forward movement arranged in series on the same axis as the
A sun gear 22 shared by 0 and 21 is connected to the turbine shaft 17.

The reverse planetary gear mechanism 20 is of a single pinion type, and the rotation of the sun gear 22
Is transmitted to a ring gear 25 via a pinion 24 supported by the ring gear 25. The carrier 23 is connected to the hollow fixed shaft 15 and fixed to the casing 10. The ring gear 25 is connected to the output shaft 30 via the reverse clutch 6a. on the other hand,
The forward planetary gear mechanism 21 is of a double pinion type, and the rotation of the sun gear 22 is transmitted to a ring gear 28 via an inner pinion 26 and an outer pinion 27 supported by the carrier 23. The ring gear 28 is connected to an output shaft 30 via a forward clutch 6b and a one-way clutch 29.

The reverse clutch 6a and the forward clutch 6b constitute a forward / reverse switching device 6.
When the reverse clutch 6a is engaged,
The input from the turbine shaft 17 is transmitted to the output shaft 30 via the reverse planetary gear mechanism 20. When the forward clutch 6b is engaged, the input from the turbine shaft 17 is transmitted to the output shaft 30 via the forward planetary gear mechanism 21.

On the other hand, in the present embodiment, the continuously variable transmission 8 of the second power transmission path 4 includes two toroidal transmissions 31 and 3.
2, both toroidal type transmissions 31, 32
Are arranged in series and coaxially with the output shaft 30 at a position adjacent to the speed reducer 7. Each of the toroidal transmissions 31 and 32 has a pair of disks 33 and 34 which are arranged apart from each other in the axial direction, and these disks 33 and 3
4 and a roller 35 that is in sliding contact with the disks 33 and 34.

One disk (output disk) 33 of the pair of disks is fixed to the output shaft 30,
The other disk (input disk) 34 is connected to the output shaft 30.
, And can move in the axial direction. The tilt angle θ of the roller 35 is changed by a hydraulic mechanism described later, and the gear ratio of the toroidal transmissions 31 and 32 is changed accordingly. That is, the rotation of the input disk 34 is transmitted to the output disk 33 via the roller 35, and the speed ratio at this time is determined by the radius Ri of the position where the roller 35 slides on the input disk 34 and the radius Ri of the position where the roller 35 slides on the output disk 33. According to the ratio with the radius Ro, when the roller 35 tilts, the sliding contact portion changes, so that the speed ratio changes.

The two toroidal transmissions 31, 32 are:
The input disk 34 is arranged inside and the output disk 33 is arranged outside. An intermediate disk 36 is disposed between the input disks 34, and a cam 37 for applying a pressing force corresponding to the input torque to the input disk 34 is provided between the intermediate disk 36 and the input disks 34. Is equipped.

The input to the continuously variable transmission 8 is performed via a bypass shaft 40 arranged in parallel with the turbine shaft 17 and the output shaft 30. That is, the first gear 41 is provided at the front end of the bypass shaft 40, and the first gear 41 is connected to the second gear via the idle gear 42.
The second gear 43 is linked to the hollow rotary shaft 18 directly connected to the input side of the torque converter (the pump impeller 12) via the path switching clutch 2. A third gear 44 is provided at the rear end of the bypass shaft 40, and the third gear 44 is meshed with a fourth gear 45 provided on the intermediate disk 36.

Therefore, when the path switching clutch 2 is off, the rotation transmission between the hollow rotary shaft 18 and the bypass shaft 40 is interrupted, and the engine output is reduced to the first level.
Is transmitted to the output shaft 30 via the torque converter 5, the forward / reverse switching device 6 and the reduction device 7 of the power transmission path 3.
On the other hand, when the path switching clutch 2 is on, the engine output is bypassed from the torque converter 5 to the continuously variable transmission 8 from the hollow rotary shaft 18 to the gears 43, 42, 41, the bypass shaft 40 and the gears 44, 45. , And the first power transmission path 3 does not substantially work because the one-way clutch 29 becomes free in this case.

The clutches 6a and 6b of the path switching clutch 2 and the forward / reverse switching device 6 are switched as shown in Table 1 according to the driving state of the vehicle.

[0022]

[Table 1]

FIG. 3 shows a hydraulic control circuit for performing the switching operation of the clutches 2, 6a and 6b and the speed ratio control of the continuously variable transmission 8. In this figure, reference numeral 51 denotes a regulator valve, which adjusts the hydraulic pressure (line pressure) of hydraulic oil discharged from the oil pump 50 according to a control pressure supplied from a reducing valve 52 via a control pressure supply line. It has become. A first duty solenoid valve 53 is connected to a control pressure supply line for the regulator valve 51, and the line pressure is controlled by the duty control.

The line pressure is controlled by a ratio control valve 54 for the toroidal transmissions 31, 32,
It is sent to the manual valve 55.

The hydraulic line led out from the ratio control valve 54 is connected to the toroidal transmission 31,
32, a pair of roller tilting actuators 5
The actuator 56 tilts the roller 35 by the operation of a piston 56a according to the oil pressure. A second duty solenoid valve 57 is provided in the pilot line for the ratio control valve 54, and the hydraulic pressure supplied to the roller tilt actuator 56 is controlled by the duty control, and the roller 35 is tilted accordingly. Thus, the gear ratio is controlled.

The manual valve 55 has an output line leading to the forward clutch 6b, an output line leading to the reverse clutch 6a,
8 and an output line extending to the path switching clutch 2. The manual valve 55 supplies hydraulic pressure to the reverse clutch 6a in the reverse travel range (R range), and supplies hydraulic pressure to the forward clutch 6a and the input side of the control valve 58 in the forward travel range (D range). It operates in response to a manual operation so that

A third duty solenoid valve 59 is provided on a pilot line for the control valve 58.
The control valve 58 is configured to supply and discharge the hydraulic pressure to and from the path switching clutch 2 in accordance with the operation of the duty solenoid valve 59.

Each of the duty solenoid valves 53,
57 and 59 are controlled by a duty control signal output from a control unit (ECU) 61. The ECU 61 receives a detection signal 71 of an engine speed, a detection signal 72 of a vehicle speed, a detection signal 73 of a throttle opening, and the like from respective sensors.

The functional configuration of the ECU 61 will be described with reference to FIG. The ECU 61 includes a line pressure control unit 62 that controls the first duty solenoid valve 53 according to the engine torque and the like, and a target speed ratio that sets the speed ratio of the continuously variable transmission 8 in the toroidal operation state described below according to the operation state. Speed ratio control means 63 for controlling the second duty solenoid valve 57, and a path switching control means 64. The path switching control means 64 sets a power transmission state (torque converter operating state) by the first power transmission path 3 in a specific operation area such as a low vehicle speed area according to an operation state such as a vehicle speed during forward running. In the operating range of, the basic control of the switching of the path switching clutch 3 is performed so that the power is transmitted by the second power transmission path 4 (toroidal operation state). An operation region (torque region) in which the first power transmission path 3 is to be used and an operation region (toroidal region) in which the second power transmission path 4 is to be used are set in advance by a map.

Further, the ECU 61 controls the path switching clutch 3
The rotation speed adjusting means 65, the torque detection means 66 and the operating speed control means 6
7 is included.

When the path switching clutch 2 is switched from the disengaged state to the engaged state, the rotational speed adjusting means 65 controls the input-side rotational speed (the rotational speed of the hollow rotary shaft 18) and the output-side rotational speed (the rotational speed of the gear 43). ) Is adjusted so that the speed ratio fluctuation ranges of the two power transmission paths 3 and 4 overlap each other. Specifically, the speed of the continuously variable transmission 8 is controlled by the duty control of the second duty solenoid valve 57. By adjusting the ratio, the above-described rotation speed adjustment is performed.

That is, when the path switching clutch 2 is disengaged, the power transmission between the input side and the output side is interrupted, but even in this state, the power transmission from the first power transmission path 3 is stopped. Since the disk and the like of the continuously variable transmission 8 are also rotating with the rotation of the output shaft 30 due to power transmission, if the speed ratio of the continuously variable transmission 8 is changed, the output side rotation speed of the switching clutch 2 changes. . Further, as shown in FIG. 5, the speed ratio variation range A due to the second power transmission path 4 is on the side where the speed ratio is relatively small, and the speed ratio variation range B due to the first power transmission path 3 is relatively small. Although set to a larger value, the maximum speed ratio i _{A of} the second power transmission path 4 is made larger than the minimum speed ratio i _{B of} the first power transmission path 3 (speed ratio of the reduction gear 7). The speed ratio fluctuation ranges of the paths 3 and 4 are set so as to partially overlap. Since the switching from the torque converter operating state to the toroidal operating state is normally performed at a position close to the minimum speed ratio of the first power transmission path 3, the overlap range a
By adjusting the speed ratio of the continuously variable transmission 8, it is possible to adjust the input-side rotational speed and the output-side rotational speed of the path switching clutch 2 before the engagement thereof.

The torque detecting means 66 detects the input torque to the path switching clutch 2 at the time of the switching operation of the path switching clutch 2, and based on, for example, the throttle opening and the engine speed, the speed ratio of the torque converter 5, and the like. To calculate the input torque.

At the time of the switching operation of the path switching clutch 2, the operating speed control means 67 performs the third operation in accordance with the input torque.
By controlling the duty solenoid valve 59, the switching operation speed is reduced as the input torque is reduced, that is, the engagement time (or the release time) is controlled to be increased as the input torque is reduced (see FIG. 6).
Specifically, the operating oil pressures P1 and P2 for the path switching clutch 2 as shown in FIG. 7 (a change in hydraulic pressure when the path switching clutch 2 is engaged) and FIG. 8 (a change in oil pressure when the path switching clutch 2 is released). And the change rates K1 and K2 thereof are set according to the input torque, and the smaller the input torque, the smaller the change rates K1 and K2 (two-dot chain lines in FIGS. 7 and 8).
Like that.

This control will be specifically described with reference to the flowchart of FIG.

When this flowchart starts, the control unit firstly operates the vehicle speed and the throttle opening TVO.
Is read (step S1). Next, it is determined whether or not the current state is the toroidal operation state, that is, whether or not the path switching clutch 25 is in the engaged state (step S2).

If the determination in step S2 is NO, that is, if the torque converter is operating, it is determined whether the operating state has shifted to the toroidal region on the map (step S3). If this determination is NO, the torque converter operating state is maintained as it is (step S4).

If the determination in step S3 is YES, while the path switching clutch 2 is in the disengaged state, the second duty solenoid valve 57 is duty-controlled so that the input side rotation speed of the path switching clutch 2 is controlled. The gear ratio of the toroidal transmissions 31 and 32 is changed so that the speed and the output side rotational speed match (step S5). Subsequently, based on the throttle opening and the like, the path switching clutch 2
Is calculated (step S6), and the hydraulic pressure P1 and the rate of change K1 (see FIG. 7) for the path switching clutch 2 are set in accordance with the input torque (step S7). The fastening time Δt1 is set to be long. Then, by controlling the third duty solenoid valve 59 so as to supply the hydraulic pressure to the path switching clutch 2 in accordance with this setting, the path switching clutch 2 is engaged and the toroidal operation state is set (steps S8 and S9).

If the determination in step S2 is YES, that is, if the vehicle is in the toroidal operation state, it is determined whether the operation state has shifted to the torque converter region on the map (step S10). When this determination is NO, the toroidal operation state is maintained as it is (step S11).

If the determination in step S10 is YES, the input torque of the path switching clutch 2 is calculated (step S12), and the hydraulic pressure P2 and the rate of change K2 (FIG. 8) for the path switching clutch 2 are calculated according to the input torque. (See step S13), and in this case, the release time Δt2 is set to be longer as the input torque is smaller.
The third duty solenoid valve 59 is configured to discharge the hydraulic pressure from the path switching clutch 2 according to this setting.
, The path switching clutch 2 is released and the torque converter is activated (steps S14 and S15).

According to the apparatus of the present embodiment as described above, basic power transmission path switching control is performed based on a map of a preset operation area, and in a specific operation area such as a low vehicle speed area, a path switching clutch is used. 2, a relatively large speed ratio and a torque multiplying action by the torque converter 5 are obtained, and in other operation regions, the toroidal operation state is established by engagement of the path switching clutch 2. Thus, transmission loss due to the torque converter 5 can be avoided and the continuously variable transmission 8
As a result, the gear ratio is adjusted on the relatively small side, which is advantageous for fuel efficiency and the like.

When the switching from the release to the engagement of the path switching clutch 2 (the switching from the torque converter operating state to the toroidal operating state) is performed, first, the input side rotation speed and the output side rotation speed of the path switching clutch 2 are switched. The switching operation of the path switching clutch 2 is performed after being adjusted so as to match, so that the transition to the toroidal operation state by the engagement of the path switching clutch 2 is smoothly performed while the slip of the path switching clutch 2 is suppressed. Will be

Further, in this case, by adjusting the hydraulic pressure supply according to the input torque of the path switching clutch 2, when the input torque is small, the engagement speed is reduced, so that
Shock accompanying switching of the power transmission path is reduced.
The input / output rotational speeds of the path switching clutch 2 match by the rotational speed adjustment prior to the switching operation as described above, and when the input torque is small, the change in the rotational speed during the switching operation is small. Even if it is made longer, wear due to slippage of the path switching clutch 2 does not occur.

When the input torque is large, if the engagement speed increases, the responsiveness of the shift to an acceleration operation or the like deteriorates, and the change of the input rotation speed during the switching operation causes the path switching clutch 2 to slip. However, such a situation can be avoided by increasing the fastening speed,
Responsibility is ensured.

On the other hand, when the switching from the engagement to the release of the path switching clutch 2 (the switching from the toroidal operation state to the torque converter operation state) is performed, the path switching clutch 2 is in the engaged state before the switching operation, and Since the input / output rotation speeds match, the rotation speed is not adjusted. However, by adjusting the hydraulic discharge according to the input torque of the path switching clutch 2,
Switching speed control is performed so that the release speed is slow when the input torque is small and the release speed is high when the input torque is large. As a result, the effect of reducing the switching shock when the input torque is small and ensuring the acceleration responsiveness when the input torque is large can be obtained as in the case of switching to the engagement of the path switching clutch 2.
10 and 11 show another embodiment of the structure of the power transmission system. In this embodiment, a torque converter 5 is provided with a lock-up clutch 80, and a first power transmission path 3 ′ having a forward / reverse switching device 6 and a speed reduction device 7 at a stage subsequent to the torque converter 5. And a second power transmission path 4 'having a continuously variable transmission 8 connected via a path switching clutch 2'.

That is, a lock-up clutch 80 is provided between the pump cover 11 of the torque converter 5 and the turbine liner 13 to directly connect the two. The forward / reverse switching device 6 and the speed reduction device 7 are connected to the turbine shaft 17 in the same manner as in the above-described embodiment (FIGS. 1 and 2), while being connected to the turbine shaft 17 via a path switching clutch 2 ′. Gear 43 on the second power transmission path 4 'side
Is connected. This gear 43 has a bypass shaft 4
0 is meshed with the gear 41 at the front end through an idle gear 42, and the rear end of the bypass shaft 40 is connected to the toroidal transmission 31,
The structure to which 32 is connected is the same as in the above-described embodiment (FIGS. 1 and 2).

In this embodiment, when the path switching clutch 2 is released, power is transmitted from the output side of the torque converter 5 through the first power transmission path 3 ', and when the path switching clutch 2' is engaged. Power is transmitted through the second power transmission path 4 'without substantially operating the first power transmission path 3'. And which of the routes 3 ', 4'
In this case, it is possible to arbitrarily select a state in which the lock-up clutch 80 is released to pass through the torque converter 5 and a state in which the lock-up clutch 80 is engaged to bypass the torque converter 5. . Therefore, as the basic control, the switching of the path switching clutch 2 'and the switching of the lock-up clutch 80 may be performed according to the operating state.

Also in the case of such a structure, when the path switching clutch 2 'is switched, the rotation speed adjusting means 6 is used.
5. Processing as torque detecting means 66 and operating speed control means 67 (see FIGS. 4 and 9) is performed.

In addition to these embodiments, for example, a stepped transmission is provided in addition to or as a reduction gear in the first power transmission path, and the stepped transmission in the first power transmission path is provided. A relatively large speed ratio can be obtained, and the continuously variable transmission in the second power transmission path may have a relatively small speed ratio, and these paths may be switchable.

[0050]

As described above, the present invention provides a first power transmission path including a speed reducer, a second power transmission path including a continuously variable transmission, and a friction element that switches between the two paths in accordance with an operation state. In the power transmission device having the above, during the switching operation of the friction element, the input side rotation speed and the output side rotation speed of the friction element are adjusted to substantially match, and according to the input torque of the friction element, The switching operation speed is controlled so as to decrease as the input torque decreases. Therefore, when the input torque is small, the switching operation of the friction element is gently performed to reduce the shock of switching the power transmission path, and furthermore, it is possible to prevent wear of the friction element, while the input torque is large. In some cases, responsiveness can be satisfied by speeding up the switching operation of the friction element.

In this configuration, the maximum speed ratio of the continuously variable transmission in the second power transmission path is made larger than the minimum speed ratio of the first power transmission path, so that the speed ratio fluctuation ranges of both transmission paths are over. If an overlapping area is provided, and the output speed of the friction element is adjusted by adjusting the speed ratio of the continuously variable transmission within the overlap area during the switching operation of the friction element, the friction element can be easily adjusted. The input-side rotation speed and the output-side rotation speed can be matched.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a power transmission path according to an embodiment of the present invention.

FIG. 2 is a block diagram conceptually showing a power transmission path of the embodiment.

FIG. 3 is a block diagram illustrating a hydraulic control circuit.

FIG. 4 is a functional block diagram of a control system.

FIG. 5 is an explanatory diagram showing a speed ratio fluctuation range and the like by each power transmission path.

FIG. 6 is a diagram showing a relationship between input torque and engagement time or release time at the time of a switching operation of a path switching clutch.

FIG. 7 is a diagram showing a change in clutch operating oil pressure when the path switching clutch is engaged.

FIG. 8 is a diagram showing a change in clutch operating oil pressure when the path switching clutch is released.

FIG. 9 is a flowchart of control.

FIG. 10 is an overall configuration diagram of a power transmission path according to another embodiment of the present invention.

FIG. 11 is a block diagram conceptually showing a power transmission path of the embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 engine 2 path switching clutch 3 first power transmission path 4 second power transmission path 5 torque converter 7 reduction gear 8 continuously variable transmission 61 control unit 64 path switching control means 65 rotation speed adjustment means 66 torque detection means 67 operation Speed control means

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-167750 (JP, A) JP-A-2-256959 (JP, A) JP-A-3-56762 (JP, A) JP-A-4-167 277357 (JP, A) JP-A-4-300449 (JP, A) JP-A-4-312261 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16H 37 / 02,47 / 06 F16H 59 / 14,61 / 06

Claims (3)

(57) [Claims] 1. A first power transmission path for transmitting an engine output to a wheel via a reduction gear, and a second power transmission path for transmitting an engine output to a wheel via a continuously variable transmission. A power transmission path switching friction element for switching a path, wherein the friction element is switched in accordance with an operation state. Rotation speed adjusting means for adjusting the number of rotations to substantially match the output side rotation speed, torque detection means for detecting an input torque at the time of the switching operation of the friction element, and switching of the friction element according to the input torque. A power transmission device for a vehicle, comprising: operating speed control means for controlling the operating speed to be lower as the input torque is smaller. 2. The power transmission device for a vehicle according to claim 1, wherein the first power transmission path passes through the torque converter, and the second power transmission path bypasses the torque converter. 3. An area in which the speed ratio fluctuation ranges of both transmission paths overlap by making the maximum speed ratio of the continuously variable transmission of the second power transmission path larger than the minimum speed ratio of the first power transmission path. The power transmission device for a vehicle according to claim 1 or 2, wherein the rotation speed adjusting means is configured to adjust the speed ratio of the continuously variable transmission in the overlap region.