JP2001289315A - Automatic transmission for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce idling and stop idling using one oil pump to surely operate an automatic transmission even when viscosity of hydraulic fluid is high. SOLUTION: This automatic transmission has the oil pump 30 supplying hydraulic fluid to a gear shift element constituting the automatic transmission shifting the rotation of a crankshaft of an engine to transmit it to a drive wheel and a planetary gear mechanism as a power synthetic mechanism 35. The planetary gear mechanism has a sun gear 37 provided on a drive shaft 36 driven by the engine and a ring gear 39 driven by an electric motor 47, and a carrier 42 provided with a pinion gear 43 meshing with the sun gear 37 and the ring gear 39 is connected to a pump drive shaft 41 connected to the oil pump 30. Consequently, the oil pump 30 is driven by engine power and motor power.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic transmission for an automobile having an oil pump for operating a transmission element of an automatic transmission.

[0002]

2. Description of the Related Art As an automatic transmission for an automobile, there are a multi-stage automatic transmission having a planetary gear mechanism, that is, a planetary gear train, and a belt-type continuously variable transmission (CVT) which performs an automatic transmission operation in a stepless manner using a belt. In any of the automatic transmissions, a transmission element that constitutes the transmission is driven by a hydraulic pressure generated by an oil pump, and the oil pump is directly connected to a crankshaft of the engine and is driven by the engine. It has become.

The driving torque Tp of the oil pump is expressed by the following equation (1), and it is desirable that the driving torque Tp be as small as possible to consume a part of the engine torque.

Tp = Vth · P / (2π) / ηm (1)
Here, ηm is the mechanical efficiency of the pump, Vth is the discharge amount per one rotation of the pump, and P is the discharge pressure.

Although it is desirable to drive the oil pump directly to the engine in order to simplify the mechanism, the oil pump discharges more oil than required by the automatic transmission, especially in a high rotation speed range. Therefore, power loss occurs in the high rotation speed range.

On the other hand, power L consumed by the oil pump is expressed by the following equation (2).

L = P · Q (2) where P is a discharge pressure and Q is a discharge amount per unit time.

[0008] Since the power consumption L of the pump is a power loss of the engine, it is a multi-stage type to control the hydraulic pressure to a minimum and to reduce the capacity of the pump in order to increase the driving efficiency of the pump. Both the automatic transmission and the belt-type continuously variable transmission have always been addressed as a technical problem. Conventionally, the following techniques have been proposed to reduce the power loss of an oil pump.

For example, the prior art 1 (Japanese Patent Laid-Open No. 3-213772) discloses a CVT hydraulic control device in which an oil pump is provided with two discharge ports. The hydraulic oil from one discharge port is returned to the suction port to reduce the power loss of the pump in the high rotation range.

[0010] Prior example 2 (Japanese Patent Application Laid-Open No. 10-331677)
In order to realize a CVT compatible with the idle stop function, an automatic transmission having two oil pumps, an engine drive pump and a motor drive pump, is disclosed. The discharge ports of these two oil pumps each have a check valve. The pump is connected to a line pressure circuit through the pump, so that an engine-driven pump and a motor-driven pump can be selectively switched.

Japanese Patent Laid-Open No. Hei 10-89445 discloses a multi-stage automatic transmission in which an oil pump is driven by an electric motor, and the operating speed of the pump is independent of the engine speed. By doing so, the power loss caused by driving the pump at a high speed is eliminated, and it is possible to cope with idle stop.

[0012]

[Problems to be Solved by the Invention] In recent years, in order to further improve fuel efficiency, attempts have been made to reduce the idling speed when the vehicle is stopped at a traffic light or the like. To lower the minimum engine speed during idling, it is necessary to increase the capacity of the oil pump in order to secure the function of the automatic transmission. In this case, in the technique of the first prior art, it is necessary to increase the discharge capacity to cope with the low idling. When the engine speed is high, the excess of the discharge amount increases, and the power loss increases. become.

[0013] Even in the case of the preceding example 2, since only the engine-driven pump operates during the operation of the engine, the capacity of the engine-driven pump must be increased in order to reduce idling, and the power loss at the time of high rotation also increases. Will be.

2. Idle stop when vehicle is stopped In order to suppress fuel consumption when the vehicle is stopped, the engine rotation is selectively stopped in some cases.

In the case of the preceding example 1, when the rotation of the engine stops, the operation of the hydraulic system also stops. During the stop, the hydraulic oil leaks from the hydraulic cylinders of the various parts and the hydraulic oil escapes from the hydraulic system due to gravity drainage. Therefore, the hydraulic pressure is not stabilized for a certain time immediately after the engine is started. For this reason, for example, if the vehicle is idle-stopped for a signal, it is required that the signal changes and the vehicle can be started immediately. However, such a time delay is not preferable for a rapid start.

3. Problems when applying an electric pump to an automatic transmission When the hydraulic source of the automatic transmission is a motor-driven pump alone, as in the preceding example 3, motor start-up reliability is required. The reason is that an automobile is required to be able to run even in an extremely low temperature environment of -30 ° C or lower, but in such an environment, the viscosity of hydraulic oil is extremely high, and if the electric motor does not have sufficient generated torque. The oil pump cannot be started. The use of a high-torque electric motor increases the weight and increases the cost.

An object of the present invention is to achieve low idling and idle stop by using one oil pump so that an automatic transmission can be reliably operated even when the viscosity of hydraulic oil is high. It is in.

[0018]

According to the present invention, there is provided an automatic transmission for an automobile having an automatic transmission for shifting the rotation of a crankshaft of an engine and transmitting the rotation to drive wheels. An oil pump that supplies hydraulic oil to the speed change element, a power of an engine torque transmission shaft driven by the engine, and a power of a motor main shaft driven by an electric motor are combined and transmitted to the oil pump. A power combining mechanism, wherein the oil pump is driven by engine power and motor power.

In the automatic transmission for an automobile according to the present invention, the power combining mechanism includes a sun gear, a ring gear arranged concentrically with the sun gear, and a carrier rotatably supporting a pinion gear meshing with the sun gear and the ring gear. A single pinion planetary gear train, wherein the carrier is connected to a pump drive shaft, one of the ring gear and the sun gear is connected to the engine torque transmission shaft, and the other is connected to the motor main shaft. And

In the automatic transmission for an automobile according to the present invention, the power combining mechanism includes a sun gear, a ring gear disposed concentrically with the sun gear, a first pinion gear meshing with the ring gear, and the sun gear and the first pinion gear. A double pinion planetary gear train having a carrier that rotatably supports the meshing second pinion gears, wherein the ring gear is connected to the pump drive shaft,
One of the carrier and the sun gear is connected to the engine torque transmission shaft, and the other is connected to the motor main shaft.

An automatic transmission for an automobile according to the present invention is characterized in that it has a one-way clutch for preventing reverse rotation of the motor main shaft.

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a skeleton diagram showing a drive system having an automatic transmission for an automobile according to an embodiment of the present invention. As the automatic transmission, a belt-type continuously variable transmission (CVT) is used.
Is used. As shown in FIG. 1, the rotation of a crankshaft 1 driven by an engine (not shown) is transmitted to a continuously variable transmission 4 via a torque converter 2 as a starting device and a forward / reverse switching device 3. It has become.

The torque converter 2 has a lock-up clutch 5, which is connected to a turbine shaft 6. One side of the lock-up clutch 5 is a supply chamber, that is, an apply chamber 7a, and the other side is an open chamber, that is, a release chamber 7b, and the hydraulic pressure supplied to the release chamber 7b is circulated through the apply chamber 7a to thereby provide a torque converter. 2 is activated.

The crankshaft 1 is directly connected to a casing 8 of the torque converter 2. An engine torque transmitting shaft 9 is fixed to the casing 8, and the engine torque transmitting shaft 9 is directly connected to the crankshaft 1 via the casing 8. Have been.

The forward / reverse switching device 3 includes a forward clutch 11 for transmitting the rotation of the turbine shaft 6 as an output shaft of the torque converter 2 to the continuously variable transmission 4 in a forward direction, and a reversing clutch for transmitting the rotation in a reverse direction. When the forward clutch 11 is connected by supplying hydraulic pressure to the clutch oil chamber 11a, the rotation of the turbine shaft 6 is controlled by the continuously variable transmission 4.
When the reverse brake 12 is connected by supplying hydraulic pressure to the brake oil chamber 12a, the speed is reduced and transmitted in the reverse direction.

The continuously variable transmission 4 has an input shaft or primary shaft 13 connected to the forward / reverse switching device 3, and an output shaft or secondary shaft 14 parallel to the input shaft. A primary pulley 15 is provided on the primary shaft 13. The primary pulley 15 is slidable in the axial direction by a ball spline or the like on the primary shaft 13 opposed to the fixed pulley 15 a fixed to the primary shaft 13. The pulley has a movable pulley 15b, and the gap between the cone surfaces of the pulley, that is, the pulley groove width is variable. A secondary pulley 16 is provided on the secondary shaft 14, and the secondary pulley 16 slides in the axial direction on the secondary shaft 14 in opposition to the fixed pulley 16a fixed to the secondary shaft 14 like the movable pulley 15b. A movable pulley 16b that is freely mounted, and the groove width of the pulley is variable.

A belt 17 is stretched between the primary pulley 15 and the secondary pulley 16, and by changing the groove width of both pulleys 15, 16, the ratio of the winding diameter to the respective pulleys 15, 16 is changed. Is changed, the rotation of the primary shaft 13 is transmitted to the secondary shaft 14 at a continuously variable speed.

The rotation of the secondary shaft 14 is transmitted to wheels 19a, 19b via a gear train having a reduction gear and a differential device 18. In the case of a front wheel drive vehicle, the wheels 19a, 19b are connected to the front wheels. Becomes
In the case of a four-wheel drive vehicle, an extension mechanism is provided between the differential device 18 and the rear wheels.

To change the groove width of the primary pulley 15, a plunger 21 having a cylindrical portion and a disk portion is fixed to the primary shaft 13.
Primary cylinder 22 that slidably contacts the outer peripheral surface of the cylinder
Is fixed to the movable pulley 15b, and the plunger 21
A drive oil chamber 23 is formed between the movable pulley 15b.

To change the groove width of the secondary pulley 16, a plunger 26 having a tapered cylindrical portion is fixed to the secondary shaft 14, and a secondary cylinder 27 slidably contacting the outer peripheral surface of the plunger 26. The drive oil chamber 28 is fixed to the movable pulley 16b, and is formed between the plunger 26 and the movable pulley 16b.

The forward / reverse switching device 3 and the continuously variable transmission 4 are incorporated in a transmission case 29, and the driving oil chambers 23 and 28 provided in the continuously variable transmission 4 and the clutch provided in the forward / reverse switching device 3 are provided. An oil pump 30 is provided to supply hydraulic oil to a transmission element that is operated by hydraulic pressure, such as the oil chamber 11a and the brake oil chamber 12a.

FIG. 2 is an enlarged sectional view showing a main part of FIG. 1, and FIG. 3 is a sectional view showing the oil pump 30 as viewed from a direction along the line AA in FIG.
Numeral 0 has a pump body 32 attached to a rear cover 31a fixed to the transmission case 29. The oil pump 30 is a trochoid pump. As shown in FIG. 3, an outer rotor 33 and an inner rotor 34 are eccentrically mounted on each other so as to be rotatable in the pump body 32. Is provided with an inner gear 33a, and an inner rotor 34
Is provided with an outer gear 34a.

A power combining mechanism 35 is provided in the pump body 32, and the power combining mechanism 35 is incorporated in a gear housing 40 attached to the pump body 32. The power combining mechanism 35 has a sun gear or sun gear 37 provided on a first drive shaft 36 and an internal gear or ring gear 39 provided concentrically and provided on a hollow second drive shaft 38. A plurality of pinion gears 43 meshing with a sun gear 37 and a ring gear 39 are rotatably mounted on a carrier 42 provided on a hollow pump drive shaft 41 rotatably mounted outside the first drive shaft 36. I have. The pump drive shaft 41 is connected to an inner rotor 34 which is a drive unit of the oil pump 30.

FIG. 4 is a skeleton diagram showing the power combining mechanism 35 as viewed from a direction along the line BB in FIG. 2. The pinion gear 43 includes a sun gear 37 and a ring gear 3 respectively.
The power combining mechanism 35 shown in FIG. 2 is a single pinion planetary gear train, that is, a single pinion type planetary gear mechanism.

As shown in FIG. 1, an engine torque transmitting shaft 9 is directly connected to the crankshaft 1 via a casing 8 of the torque converter 2, and a driving sprocket 44 is fixed to the engine torque transmitting shaft 9. A chain 46 is mounted on the driven sprocket 45 and the driven sprocket 44 fixed to the first drive shaft 36,
The drive shaft 36 is driven by the engine. These sprockets 44, 45 and chain 4
6 is a front cover 3 fixed to the rear cover 31a.
1b.

As shown in FIG. 2, an electric motor 47 is mounted on the transmission case 29, and a motor main shaft 48 of the electric motor 47 is directly connected to the second drive shaft 38 and a pump drive shaft 41 provided with a carrier 42. Denotes an inner rotor 3 as a pump drive unit of the oil pump 30
4.

Thus, the sun gear 37 is connected to the first drive shaft 3
6, and the ring gear 39 is connected to the second
It is connected to the motor main shaft 48 via the drive shaft 38,
The oil pump 30 is configured such that engine power and motor power are combined by a power combining mechanism 35 and transmitted to an inner rotor 34 as a pump drive unit. However, the sun gear 37 may be driven by the electric motor 47 and the ring gear 39 may be driven by the engine.

FIG. 5 is a block diagram showing a control unit 50 for controlling the rotation of the electric motor 47. The control unit 50 includes a target motor rotation setting unit 51, a motor driver 52 for driving the motor in accordance with the target value, and a fail detection unit 5.
And the motor rotation speed is determined by the motor driver 5 based on the signal of the rotation sensor 54 attached to the electric motor 47.
2 is feedback controlled.

In order to determine the target motor speed, the target motor speed setting section 51 includes a throttle opening signal 5
5, an engine speed signal 56, a vehicle speed signal 57, a range switch signal 58, a brake switch signal 59, and a hydraulic oil temperature signal 60 are respectively transmitted.

The target motor rotation setting section 51 is connected to a bidirectional signal line for sending and receiving an engine cooperation signal 61 and a transmission cooperation signal 62. The engine coordination signal 61 receives, for example, an idle stop notice signal from the engine or sends out an idle stop prohibition signal when the motor fails. The transmission coordination signal 62 receives, for example, a pump rotation up request or sends out a fail signal to cause the transmission to change the lockup schedule or the shift line.

In general, the speed-related equation for a single planetary gear train is expressed by the following equation (3), and the pump speed ωc is the sum of the engine speed ωs and the motor speed ωr.

Ωr · Zr + ωs · Zs = ωc × (Zr +
Zs) (3) where Zr is the number of teeth of the ring gear, and Zs is the number of teeth of the sun gear.

FIG. 6 is a characteristic diagram showing the relationship of the equation (3). In this figure, the motor speed ωr is plotted on the horizontal axis and the motor speed ωr on the vertical axis under the condition that the engine speed ωs is constant. The rotation speed ωc is shown. The pump rotation speed ωc when the motor rotation speed ωr is 0 is {Zs / (Zr + Zs)}
.Omega.s, and the oil pump 30 is driven at a rotation speed reduced with respect to the engine rotation speed. When the motor rotational speed ωr is increased to match the engine rotational speed ωs, the pump rotational speed ωc becomes the same as the engine rotational speed ωs, and when the motor rotational speed ωr is further increased, the pump is rotated at a rotational speed exceeding the engine rotational speed ωs. Can be driven.

Therefore, in the illustrated automatic transmission, the required flow rate of the working oil can be ensured by increasing the rotation of the electric motor 47 even when the engine is running at a low speed. In particular, the electric motor 47 even when the engine is stopped.
Thus, the oil pump 30 can be driven.

Conversely, if the rotation of the electric motor 47 is reduced, the number of rotations of the oil pump 30 is reduced, so that the power loss can be reduced. To further reduce the rotation speed of the oil pump, the electric motor 47 is rotated in the reverse direction.
In the case of reverse rotation, part of the engine torque is
Therefore, if a regenerative circuit is connected to the electric motor 47, it can be used as electric energy and the number of revolutions of the oil pump 30 can be efficiently controlled.

Even when the electric motor 47 cannot be started, the oil pump can be driven by the rotation of the engine, so that the reliability of the automatic transmission can be improved.

In particular, if a motor with a brake, that is, a motor with an electromagnet type mechanical brake that locks the rotation of the motor when power is not supplied, is used as the electric motor 47, the motor may run idle due to coil disconnection or breakage of the driver circuit. Also, since the pump can be driven only by the engine, the reliability of the automatic transmission can be improved.

Further, since the planetary gear train is used as the power combining mechanism 35, the pump driving torque can be distributed to the electric motor 47 and the engine, and the load on the motor can be reduced. The following equation shows the distribution ratio of the pump driving torque.

Engine sharing torque Te = {Zs / (Zr + Zs)} · Tp (4) Motor sharing torque Tm = {Zr / (Zr + Zs)} · Tp (5) where Tp is the driving torque of the oil pump. As can be seen from these equations, the torque shared by the electric motor 47 is smaller than when the pump is driven by the motor alone, so that the electric motor 47 can be reduced in size and weight.

FIG. 7 is a sectional view showing a portion corresponding to FIG. 2 of the above-mentioned embodiment in an automatic transmission for a vehicle according to another embodiment of the present invention.

In this automatic transmission, a second drive shaft 38 provided with a ring gear 39 and a gear housing 40
One-way clutch 49
When the motor main shaft 48 rotates forward, the rotation is transmitted to the ring gear 39, and when the ring gear 39 rotates reversely, the reverse rotation of the motor main shaft 48 is restricted so that the ring gear 39 can only perform normal rotation. I have. Thus, it is not necessary to use a motor with a brake as in the above-described embodiment. That is, when the electric motor 47 cannot be started, the ring gear 39
Is supported by the gear housing 40 via the one-way clutch 49, so that the oil pump 30 is driven only by the engine. The one-way clutch 49 is small in size, has a high torque load capacity, and has less restrictions on the use environment than a brake. Therefore, the size and weight of the electric motor 47 can be reduced as compared with the case where a motor with a brake is used. However, in the pump rotation range shown in FIG. 6, the low rotation portion of the pump realized by the reverse rotation of the electric motor 47 cannot be used, so that it is necessary to select the low rotation portion according to the fluctuation range of the consumption flow rate of the hydraulic system. .

FIG. 8 is a skeleton diagram showing a main part of an automatic transmission for a vehicle according to another embodiment of the present invention, and FIG. 9 is a skeleton diagram showing a portion along line CC in FIG. .

As described above, the driving torque of the oil pump 30 is distributed to the engine and the electric motor 47 by the power combining function of the planetary gear mechanism, that is, the planetary gear train, and the larger the torque sharing ratio, the more strongly the pump rotation speed. Has characteristics. Generally, in a single pinion planetary gear train, Zr / Zs = 1.5-3, so that the share of the motor is 60% -75%. If the input member of the planetary gear train is reversed and the sun gear is connected to the motor main shaft 48 of the electric motor 47 and the ring gear 39 is connected to the engine, the motor sharing ratio can be easily reduced (40% to 25%).
%) Can be covered. Motor sharing ratio is 25%
In the case where the number is smaller than the above range, or the region exceeding 75% can be realized by setting extremely large specifications in the ring gear 39, but there is little difference between the case where there is no motor or only the motor and there is little practical demand.

In the embodiment shown in FIGS. 8 and 9, it is considered that there is a practical demand, and it is possible to realize a sharing ratio of about 50%, which cannot be applied to a single pinion planetary gear train.

In this embodiment, the sun gear 37
Is mounted on a first drive shaft 36 in the same manner as described above, and this drive shaft 36 is connected via a chain 46 to an engine torque transmission shaft 9 directly connected to the crankshaft 1 of the engine. On the other hand, the carrier 42 is connected to the motor main shaft 48 via the second drive shaft 38 as shown in FIG. 8, and the ring gear 39 is connected to the inner rotor 34 of the oil pump 30, that is, the drive unit via the hollow pump drive shaft 41. Have been. A first pinion gear 43a meshing with the ring gear 39 and a second pinion gear 43b meshing with the pinion gear 43a and the sun gear 37 are rotatably mounted on the carrier 42 as a pair. Reference numeral 35 denotes a double pinion planetary gear train, that is, a double pinion type planetary gear mechanism.

The speed-related equation and torque-related equation of the double pinion planetary gear train are as follows.

Ωr · (Zr−Zs) + ωs · Zs = ωr × Zr (6) Engine sharing torque Te = (Zs / Zr) · Tp (4) Motor sharing torque Tm = ｛(Zr−Zs) / Zr ｝ Tp (5) If Zr / Zs = 2, the motor sharing ratio is 50%. Therefore, if the power combining mechanism 35 is a double pinion planetary gear train, the motor sharing ratio is difficult to obtain with a single pinion planetary gear train. It can complement a single pinion planetary gear train.

In this type of power combining mechanism 35, the sun gear 37 may be driven by the motor main shaft 48 and the carrier 42 may be driven by the electric motor 47. A one-way clutch 49 for preventing reverse rotation may be provided.

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

For example, although the torque converter 2 is provided in the drive system shown in FIG. 1, the present invention can be applied to a case without the torque converter. FIG. 1 shows a drive system having a continuously variable transmission 4 as an automatic transmission. Even when a multi-stage automatic transmission is provided, an oil pump for driving a shift element constituting the same is shown in FIG. can do.

[0062]

According to the present invention, one oil pump for operating a shift element in an automatic transmission can be driven by the engine and the electric motor, so that the engine can be driven without increasing the size of the transmission. Alternatively, the oil pump can be driven only by the electric motor or by both the engine and the electric motor.

Even if the idling speed is reduced, it is not necessary to increase the capacity of the oil pump.

Even if the idling rotation is stopped when the vehicle stops, the operation of the automatic transmission can be brought into a stable state immediately after the engine is started.

Even when the viscosity of the hydraulic oil is high, the automatic transmission can be reliably operated by starting the oil pump.

By using the power combining mechanism as the planetary gear mechanism, engine power and electric motor power can be combined and transmitted to the oil pump in a limited space.
In addition, the burden ratio of the pump driving torque for driving the oil pump by the electric motor can be easily changed.

[Brief description of the drawings]

FIG. 1 is a skeleton diagram showing a drive system having an automobile automatic transmission according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a main part of FIG. 1;

FIG. 3 is a sectional view showing the oil pump as viewed from a direction along the line AA in FIG. 2;

FIG. 4 is a skeleton diagram showing a power combining mechanism as viewed from a direction along line BB in FIG. 2;

FIG. 5 is a block diagram showing a control unit for controlling the rotation of the electric motor.

FIG. 6 is a characteristic diagram showing operating characteristics of the oil pump shown in FIG.

FIG. 7 is a cross-sectional view showing a portion corresponding to FIG. 2 of the embodiment in an automobile automatic transmission according to another embodiment of the present invention.

FIG. 8 is a skeleton diagram showing a main part of an automatic transmission for a vehicle according to another embodiment of the present invention.

FIG. 9 is a skeleton diagram showing a portion along a line CC in FIG. 8;

[Explanation of symbols]

 Reference Signs List 1 crankshaft 2 torque converter 9 engine torque transmission shaft 29 transmission case 30 oil pump 32 pump body 33 outer rotor 34 inner rotor 35 power combining mechanism 36 first drive shaft 37 sun gear 38 second drive shaft 39 ring gear 41 pump drive shaft 42 carrier 43, 43a, 43b Pinion gear 44, 45 Sprocket 47 Electric motor 48 Motor spindle 49 One-way clutch

 ──────────────────────────────────────────────────続 き Continued on front page F-term (reference)

Claims (4)

[Claims] 1. An automatic transmission for an automobile having an automatic transmission for shifting the rotation of a crankshaft of an engine and transmitting the rotation to drive wheels, comprising: an oil pump for supplying hydraulic oil to a transmission element constituting the automatic transmission. A power combining mechanism that combines the power of an engine torque transmission shaft driven by the engine and the power of a motor main shaft driven by an electric motor and transmits the combined power to the oil pump; An automatic transmission for an automobile, wherein the automatic transmission is driven by a motor and a motor power. 2. The automatic transmission according to claim 1, wherein the power combining mechanism rotatably supports a sun gear, a ring gear disposed concentrically with the sun gear, and a pinion gear meshing with the sun gear and the ring gear. A single pinion planetary gear train having a carrier, wherein the carrier is connected to a pump drive shaft, one of the ring gear and the sun gear is connected to the engine torque transmission shaft, and the other is connected to the motor main shaft. An automatic transmission for a vehicle, comprising: 3. The automatic transmission according to claim 1, wherein the power combining mechanism includes a sun gear, a ring gear arranged concentrically with the sun gear, a first pinion gear meshing with the ring gear, and the sun gear and the first gear. And a carrier that rotatably supports second pinion gears meshing with the pinion gears.A double pinion planetary gear train, wherein the ring gear is connected to the pump drive shaft, and one of the carrier and the sun gear An automatic transmission for an automobile, wherein the automatic transmission is connected to an engine torque transmission shaft, and the other is connected to the motor main shaft. 4. The automatic transmission according to claim 1, further comprising a one-way clutch for preventing the motor main shaft from rotating in a reverse direction.