JP2001153191A - Motive power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motive power transmission device capable of imparting braking force in a noncontact state to one of rotary elements for constituting a planetary gear mechanism. SOLUTION: This motive power transmission device provided with an input shaft driven by motive power of a prime mover, an output shaft arranged on the same shaft as the input shaft and a planetary gear mechanism arranged between the input shaft and the output shaft, is provided with a braking drum composed of a magnetic material connected to one of rotary elements for constituting the planetary gear mechanism and a permanent magnet movably arranged in the shaft direction on the outer peripheral side of the braking drum so as to regulate rotation. This permanent magnet is positioned in a braking position opposed to an outer peripheral surface of the braking drum and a braking releasing position unopposed to the outer peripheral surface of the braking drum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power transmission device mounted on a vehicle or the like, and more particularly to a power transmission device having a planetary gear mechanism.

[0002]

2. Description of the Related Art A planetary gear mechanism comprises a sun gear, a ring gear disposed concentrically with the sun gear, a planetary gear meshing with the ring gear and the sun gear, and a rotating element such as a planetary carrier for supporting the planetary gear. . Such a planetary gear mechanism fixes power to the input side by fixing any one of the sun gear, the ring gear, and the planetary carrier, and connecting the remaining one to the input side and the other to the output side. It can be transmitted to the output side via a planetary gear mechanism. Conventionally, in a power transmission device having such a planetary gear mechanism, a brake band or a multi-plate disc brake has been generally used as a means for fixing any one of a sun gear, a ring gear, and a planetary carrier constituting the planetary gear mechanism. ing.

[0003]

However, since the brake band and the multiple disc brake brake the rotational force by the frictional force, they are worn and have a problem in durability.

[0004] The present invention has been made in view of the above-mentioned facts, and a main technical problem thereof is to provide a power transmission device capable of applying a braking force to one of the rotating elements constituting a planetary gear mechanism in a non-contact manner. Is to do.

[0005]

According to the present invention, to solve the above-mentioned main technical problems, an input shaft driven by the power of a prime mover and an output shaft arranged on the same shaft as the input shaft are provided. A power transmission device comprising a shaft, and a planetary gear mechanism disposed between the input shaft and the output shaft;
A braking drum made of a magnetic material connected to one of the rotating elements constituting the planetary gear mechanism, magnet means arranged on the outer peripheral side of the braking drum so as to be restricted in rotation and axially movable; There is provided a magnet operating means for operating the magnet means in the axial direction and positioning the braking means at a braking position facing the outer peripheral surface of the brake drum and at a braking release position not facing the outer peripheral surface of the braking drum. A power transmission device is provided.

Further, according to the present invention, an input shaft driven by the power of a prime mover, an output shaft disposed on the same axis as the input shaft, and an output shaft disposed between the input shaft and the output shaft. A power transmission device having a plurality of planetary gear mechanisms provided therein, a braking drum made of a magnetic material connected to one of rotating elements constituting each of the plurality of planetary gear mechanisms, and each of the braking drums Magnet means arranged on the outer circumference of the brake drum so as to be restricted in rotation and movable in the axial direction, the magnet means being actuated in the axial direction, and a braking position facing each outer circumferential surface of each of the brake drums and each of the brake drums And a magnet actuating means positioned at a braking release position that does not face the outer peripheral surface of the power transmission device.

One of the plurality of planetary gear mechanisms has a mechanism for reversing the rotation direction.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a power transmission device constructed according to the present invention will be described below in more detail with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram in which a power transmission device configured according to the present invention is applied to a speed increasing device. The speed increasing device shown in FIG. 1 includes an input shaft 2 driven by the power of a prime mover, an output shaft 3 disposed on the same shaft as the input shaft 2, and a drive shaft between the input shaft 2 and the output shaft 3. And a planetary gear mechanism 4 disposed at The planetary gear mechanism 4 includes a sun gear 41, a ring gear 42, a planetary gear 43, and a rotating element of a planetary carrier 44. The sun gear 41 is attached to the output shaft 3. The ring gear 42 is disposed concentrically with the sun gear 41,
The input shaft 2 is rotatably supported. The planetary gear 43 is rotatably supported by a planetary carrier 44 and is disposed so as to mesh with the sun gear 41 and the ring gear 42. A planetary carrier 44 that rotatably supports the planetary gear 43 is attached to the input shaft 2.
The planetary gear mechanism 4 configured as described above includes a ring gear 4
2 can be transmitted to the output shaft 3 by increasing the rotation of the input shaft 2 by applying a braking force to the output shaft 3 and releasing the fixing or braking of the ring gear 42 from the input shaft 2 to the output shaft 3. Power transmission to the vehicle.

In the embodiment shown in FIG. 1, a rotary element braking means 5 for applying a braking force to the ring gear 42 is provided.
Is provided. The rotating element braking means 5 includes a braking drum 6 connected to a ring gear 42 in the illustrated embodiment.
And magnet means 7 arranged on the outer peripheral side of the braking drum 6,
And magnet operating means 8 for operating the magnet means 7 in the axial direction. The braking drum 6 is made of a magnetic material. As shown in FIG. 2, the magnet means 7 includes a magnet support ring 71, first permanent magnets 72 annularly disposed on the inner peripheral surface of the magnet support ring 71, and the first permanent magnets 72.
And second permanent magnets 73 that are annularly arranged adjacent to each other in the axial direction. The magnet support ring 71 is formed of a magnetic material, and has a plurality of guide grooves 711 provided in an axial direction on an outer peripheral surface thereof. The magnet support ring 71 is configured to be restricted in rotation but slidable in the axial direction by fitting the guide groove 711 to a plurality of guide rails 11 provided in the apparatus housing 10 in the axial direction. You. In the illustrated embodiment, the first permanent magnet 72 has magnetic poles on the outer surface joined to the inner surface of the magnet support ring 71 and the inner surface facing the braking drum 6 as shown in FIGS. 2 and 3. Are formed on the N pole and the outer surface is formed on the S pole.
The second permanent magnet 73 has an S-pole on the inner surface and an N-pole on the outer surface. The first permanent magnet 72 and the second permanent magnet 73 may be divided into a plurality (two to six) and disposed annularly, or may be integrally formed annularly. . The magnet means 7 configured in this manner is actuated in the axial direction by the magnet actuation means 8. The magnet actuating means 8 comprises an air cylinder 81 in the illustrated embodiment, and the magnet means 7 is disposed at a braking position opposed to the outer peripheral surface of the braking drum 6 indicated by a solid line in FIG. 6 is located at a release position that does not face the outer peripheral surface.

The magnet means 7 constructed as described above is used in FIG.
3, the permanent magnets 72, 73, the magnet support ring 71, and the magnetic circuit 74 passing through the brake drum 6 are formed as shown in FIG. 3 when positioned at a fixed position facing the outer peripheral surface of the brake drum 6. As a result, the ring gear 42
If the braking drum 6 connected to the motor is rotating, the magnet means 7
And a braking drum 6 generate a relative speed difference, an eddy current is generated on the inner peripheral surface of the braking drum 6 by the relative speed difference, and the braking drum 6, that is, the ring gear 42 receives a braking torque. As a result, the rotational torque of the input shaft is transmitted to the planetary carrier 44, and the planetary gear 43 revolves while rotating along the ring gear 42, so that the output shaft 3 is accelerated via the sun gear 41 meshing with the planetary gear 43. . The rotation speed of the braking drum 6, that is, the ring gear 42, is reduced by receiving the braking torque based on the eddy current. However, when the rotation speed is reduced, the braking torque based on the eddy current is not generated. For this reason, the ring gear 42 rotates around a predetermined low rotation speed even during torque transmission. On the other hand, when the magnet means 7 is positioned at the braking release position shown by the two-dot chain line in FIG. 1, the magnetic force of the magnet means 7 does not act on the braking drum 6 and the ring gear 42 is rotatable, so that the output from the input shaft 2 Power transmission to shaft 3 is shut off. As described above, in the embodiment shown in FIGS. 1 to 3, the rotating element braking means 5 for braking the ring gear 42 functions as a clutch without mechanical contact in the power transmission device.

Next, another embodiment of the magnet means 7 will be described with reference to FIGS. The magnet means 7 shown in FIGS. 4 and 5 has a plurality of first permanent magnets 72 and a plurality of second permanent magnets 73 alternately arranged in the circumferential direction on the inner peripheral surface of a magnet support ring 71. It is. First permanent magnet 72
The outer surface joined to the inner surface of the magnet support ring 71 and the inner surface facing the braking drum 6 are magnetic poles, and the inner surface is configured as an N pole and the outer surface is configured as an S pole. In addition, the second permanent magnet 7
No. 3 has an S-pole inner surface and an N-pole outer surface. When the magnet means 7 configured as described above is positioned at a fixed position facing the outer peripheral surface of the braking drum 6, as shown in FIG. 5, the permanent magnets 72 and 73 and the magnet support ring 71 and the A magnetic circuit 74 passing through the drum 6 is formed. As a result, if the brake drum 6 is rotating, a relative speed difference is generated between the magnet means 7 and the brake drum 6, and an eddy current is generated on the inner peripheral surface of the brake drum 6 due to the relative speed difference.
A braking torque is generated on the braking drum 6. 4 and 5
Has a configuration in which the first permanent magnets 72 and the second permanent magnets 73 are alternately arranged in the circumferential direction, so that the dimension in the width direction can be reduced.

Next, an example in which the present invention is applied to a reduction gear will be described with reference to FIG. The embodiment shown in FIG.
Except that the sun gear 41 of the planetary gear mechanism 4 is attached to the input shaft 2 and the planetary gear 43 is attached to the output shaft 3, it is substantially the same as the embodiment shown in FIGS. The members are given the same reference numerals,
The description is omitted. In the embodiment shown in FIG. 6, the magnet means 7 of the rotating element braking means 5 is positioned at a braking position opposite to the outer peripheral surface of the braking drum 6 shown by a solid line in the figure, and applies a braking force to the braking drum 6, that is, the ring gear 42. Accordingly, the rotation of the input shaft 2 can be increased and transmitted to the output shaft 3. When the magnet means 7 is positioned at the braking release position indicated by a two-dot chain line in the figure, the magnetic force of the magnet means 7 does not act on the braking drum 6 and the ring gear 42 becomes rotatable. The power transmission to is shut off. As described above, also in the embodiment shown in the figure, the rotating element fixing means 5 for fixing the ring gear 42 is used.
Functions as a clutch without mechanical contact in the power transmission.

Next, an example in which the present invention is applied to a transmission will be described with reference to FIG. In the embodiment shown in FIG. 7, the same members as those in the above embodiments are denoted by the same reference numerals, and description thereof will be omitted. In the embodiment shown in FIG. 7, a first planetary gear mechanism 4a, a second planetary gear mechanism 4b, a third planetary gear mechanism 4c, and a fourth planetary gear mechanism are provided between an input shaft 2 and an output shaft 3. 4d and a fifth planetary gear mechanism 4e are provided. The first planetary gear mechanism 4a includes a sun gear 4 like the planetary gear mechanism 4 described above.
1a, a ring gear 42a, a planetary gear 43a, and a planetary carrier 44a.
The sun gear 41a is mounted on the input shaft 2 and rotatably supports the planetary gear 43a.
4 a is attached to the output shaft 3. In the illustrated embodiment, the planetary carrier 44a has a large tooth width. The first braking drum 6a is connected to the ring gear 42a.

The second planetary gear mechanism 4b includes a sun gear 41.
b is attached to the input shaft 2, and a planetary carrier 44b that rotatably supports the planetary gear 43a is connected to the ring gear 42a of the first planetary gear mechanism 4a. The second braking drum 6b is connected to the ring gear 42b.

The third planetary gear mechanism 4c includes a sun gear 41.
c is rotatably disposed on the input shaft 2, and a ring gear 42c
Is connected to the ring gear 42b of the second planetary gear mechanism 4b, and a planetary carrier 44c rotatably supporting the planetary gear 43c is attached to the input shaft 2. The third braking drum 6c is connected to the ring gear 42c.

The fourth planetary gear mechanism 4d includes a sun gear 41.
d is connected to the sun gear 41c of the third planetary gear mechanism 4c and rotatably disposed on the input shaft 2. A ring gear 42d is mounted on the input shaft 2 and a planetary gear 43
A fourth braking drum 6d is connected to a planetary carrier 44d that rotatably supports d.

The fifth planetary gear mechanism 4e includes a ring gear 4
A planetary gear 43e meshing with 2e is configured to mesh with the planetary gear 43a of the first planetary gear mechanism 4a, and a planetary carrier 44e rotatably supporting the planetary gear 43a is attached to the input shaft 2. The ring gear 42e has a fifth braking drum 6e.
Are connected. A predetermined interval is provided between the fifth braking drum 6e and the first braking drum 6a.

The transmission as the power transmission in the embodiment shown in FIG. 7 includes the above-mentioned braking drums 6a, 6b, 6
c, 6d and 6e, ie, a ring gear 42a, a ring gear 42b, a sun gear 41c, and a planetary carrier 44d.
And a rotating element braking means 5 for selectively applying a braking force to the ring gear 42e. The rotating element braking means 5 comprises magnet means 7 and magnet operating means 8 for operating the magnet means 7 in the axial direction. The magnet actuating means 8 moves the magnet means 7 to a neutral position (N) located between the first braking drum 6a and the fifth braking drum 6e.
(Brake release position that does not face the outer peripheral surface of any brake)
And the first speed position facing the outer peripheral surface of the first braking drum 6a
(I), a second speed position (II) facing the outer peripheral surface of the second braking drum 6b, a third speed position (III) facing the outer peripheral surface of the third braking drum 6c, and a fourth braking drum. In the figure of the fourth speed position (IV) facing the outer peripheral surface of 6d and the neutral position (N), the vehicle is selectively positioned at the reverse position (R) on the right side.

The transmission shown in FIG. 7 is configured as described above, and its operation will be described below. Magnet means 7
Is located at the neutral position (N) as shown in FIG. 7, the ring gear 42 of the first planetary gear mechanism 4a
a and the ring gear 42b of the second planetary gear mechanism 4b and the third
Since the sun gear 41c of the planetary gear mechanism 4c, the planetary carrier 44d of the fourth planetary gear mechanism 4d, and the ring gear 42e of the fifth planetary gear mechanism 4e are not fixed, the power transmission from the input shaft 2 to the output shaft 3 is not performed. Will be shut off.

When the transmission is operated at the first speed, the braking force acts on the brake drum 6a, that is, the ring gear 42a of the first planetary gear mechanism 4a when the magnet means 7 is positioned at the first speed position (I). As a result, the rotational torque transmitted to the input shaft 2 is transmitted from the sun gear 41a of the first planetary gear mechanism 4a to the planetary gear 43a, and the planetary gear 43a revolves while rotating along the ring gear 42a. The power is transmitted to the output shaft 3 via the transmission shaft 44a. In this case, the rotation speed of the input shaft 2 is reduced and transmitted to the output shaft 3. In the illustrated embodiment, the first speed corresponds to the gear ratio (λ1) between the sun gear 41a and the ring gear 42a.
) (The ratio of the number of teeth of the sun gear 41a to the number of teeth of the ring gear 42a) is 1: 2, the speed ratio (φ1) is φ
When 1 = λ1 / (1 + λ1), it becomes 0.333, and the torque ratio becomes about three times.

When the transmission is operated at the second speed, when the magnet means 7 is positioned at the second speed position (II), a braking force acts on the braking drum 6b, that is, the ring gear 42b of the second planetary gear mechanism 4b. When a braking force is applied to the ring gear 42b, the rotational torque transmitted to the input shaft 2 is applied to the second planetary gear mechanism 4
b is transmitted from the sun gear 41b to the planetary gear 43b, and the planetary gear 43b revolves while rotating along the ring gear 42b. As a result, the power transmitted to the ring gear 42b is transmitted to the output shaft 3 via the planetary carrier 44b, the ring gear 42a of the first planetary gear mechanism 4a, the planetary gear 43a, and the planetary carrier 44a. In this case, the rotation speed of the input shaft 2 is transmitted to the output shaft 3 after being increased from the case of the first speed described above. In the illustrated second embodiment, the speed ratio (λ2) (the ratio between the number of teeth of the sun gear 41b and the number of teeth of the ring gear 42b) is 1: 2 when the gear ratio of the sun gear 41b and the ring gear 42b is 1: 2. φ2) is φ2 = λ2 / (1 + λ)
1) · (1 + λ2), which is 0.556, and the torque ratio is about 1.8 times.

When the transmission is operated at the third speed, when the magnet means 7 is positioned at the third speed position (III), a braking force acts on the braking drum 6c, that is, the sun gear 41c of the third planetary gear mechanism 4c. When a braking force is applied to the sun gear 41c, the rotational torque transmitted to the input shaft 2 is changed to the third planetary gear mechanism 4c.
From the planetary carrier 44c to the planetary gear 43c
And the planetary gear 43c revolves around the sun gear 41c while rotating. As a result, the power transmitted to the planetary gear 43c is transmitted to the ring gear 42c, the ring gear 42b of the second planetary gear mechanism 4b connected to the ring gear 42c, the planetary gear 43b, the planetary carrier 44b, and the ring gear of the first planetary gear mechanism 4a. The power is transmitted to the output shaft 3 via the planetary gear 42a, the planetary gear 43a, and the planetary carrier 44a. In this case, the rotation speed of the input shaft 2 is increased and transmitted to the output shaft 3. The third speed in the illustrated embodiment is the gear ratio (λ3) of the sun gear 41c and the ring gear 42c (the sun gear 41c
(The ratio of the number of teeth of the ring gear 42c to the number of teeth of the ring gear 42c) is 1: 2, the speed ratio (φ3) is φ3 = ｛1 / (1 + λ).
1) · (1 + λ2)｝ × (1 + λ1 + λ2 + λ)
3) In the above, 1.111 is obtained, and the torque ratio becomes about 0.9 times.

When the transmission is operated at the fourth speed, if the magnet means 7 is positioned at the fourth speed position (IV), a braking force acts on the braking drum 6d, that is, the planetary carrier 44d of the fourth planetary gear mechanism 4d. When a braking force is applied to the planetary carrier 44d, the rotational torque transmitted to the input shaft 2 is transmitted to the ring gear 42d to rotate the planetary gear 43d and rotate the sun gear 41d. As a result, the power transmitted to the sun gear 41d is transmitted to the sun gear 43c, the planetary gear 43c, the ring gear 42c, and the ring gear 4c of the third planetary gear mechanism 4c connected to the sun gear 41d.
Ring gear 42b, planetary gear 42b, planetary carrier 4 of second planetary gear mechanism 4b
4b, ring gear 42 of the first planetary gear mechanism 4a
a, planetary gear 43a, planetary carrier 44a
Is transmitted to the output shaft 3 via the. In this case, the rotation speed of the input shaft 2 is further increased and transmitted to the output shaft 3 as compared with the above-described third speed. In the illustrated embodiment, the fourth speed corresponds to the gear ratio (λ4) between the sun gear 41c and the ring gear 42d.
) (The ratio of the number of teeth of the sun gear 41c to the number of teeth of the ring gear 42d) is 1: 2, the speed ratio (φ4) is φ
3 = {1 / (1 + λ1) · (1 + λ2)} × ｛(λ
3 / λ4) + (λ3 + λ2 + λ1 + 1)｝
Thus, the torque ratio becomes about 0.64 times.

Next, when the transmission is operated in reverse, when the magnet means 7 is positioned at the reverse position (R), a braking force acts on the brake drum 6e, that is, the ring gear 42e of the fifth planetary gear mechanism 4e. When a braking force acts on the ring gear 42e, the rotational torque transmitted to the input shaft 2 is changed from the sun gear 41a of the first planetary gear mechanism 4a to the planetary gear 43a.
And the planetary gear 43a is driven. When the planetary gear 43a is driven, the planetary gear 43e of the fifth planetary gear mechanism 4e revolves while rotating along the ring gear 42e. This planetary gear 43e
Is driven by the planetary gear 43a of the first planetary gear mechanism 4a, so that the rotation direction is reversed. As a result, the power transmitted to the planetary gear 43e drives the output shaft 3 in the reverse direction via the planetary carrier 44e. In the illustrated embodiment, the reverse travel is performed by the sun gear 4.
1a and the gear ratio (λ5) of the ring gear 42e (the ratio of the number of teeth of the sun gear 41a to the number of teeth of the ring gear 42e) is 0.
In the case of 3: 1, the speed ratio (φ5) is φ5 = −
(Λ5 / (1−λ5)) is 0.429, and the torque ratio is about 2.3 times.

As described above, in the transmission shown in FIG. 7, the magnet means 7 is moved to the first speed position (I), the second speed position (II), the third speed position (III), the fourth speed position (IV) and the reverse speed. By selectively positioning at the position (R), it is possible to obtain an output of a predetermined gear ratio. Rotating element fixing means 5 for applying a braking force to the ring gear, sun gear, and planetary carrier.
Is a braking mechanism using eddy current, so that there is no mechanical contact portion and durability can be improved. In addition, in the braking mechanism using the eddy current, a sliding force is generated between the braking drum and the magnet means to apply a braking force, and the planetary gear mechanism can function. Therefore, the input shaft 2 of the transmission shown in FIG. Even when the vehicle is directly connected to an internal combustion engine which is a prime mover of the vehicle, the vehicle can be driven to start from a stopped state. That is, when the transmission configured according to the present invention is applied to a transmission of a vehicle, it is possible to eliminate a fluid coupling such as a friction clutch and a torque converter used for starting the vehicle.

[0027]

Since the power transmission device according to the present invention is constructed as described above, the following effects can be obtained.

That is, according to the present invention, a braking drum made of a magnetic material is connected to one of the rotating elements constituting the planetary gear mechanism disposed between the input shaft and the output shaft, and Since the magnet means is arranged on the outer peripheral side so as to be restricted in rotation and movable in the axial direction, by positioning the magnet means at a braking position facing the outer peripheral surface of the braking drum, a relative speed difference between the magnet means and the braking drum is obtained. An eddy current can be generated on the inner peripheral surface of the braking drum to apply a braking force to one of the braking drums or rotating elements. As a result, since the planetary gear mechanism can function and transmit power without making mechanical contact, it is possible to obtain a power transmission device that is excellent in durability without wear. Further, in the present invention, a transmission is configured by arranging a plurality of planetary gear mechanisms, and when the transmission is mounted on a vehicle, the vehicle can be driven to start even if the input shaft is directly connected to the prime mover. Thus, it is possible to eliminate a fluid coupling such as a friction clutch and a torque converter used for starting the vehicle.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram in which a power transmission device configured according to the present invention is applied to a speed increasing device.

FIG. 2 is an essential part perspective view showing one embodiment of a magnet unit constituting the power transmission device shown in FIG. 1;

FIG. 3 is an enlarged cross-sectional view showing one embodiment of a rotating element braking means constituting the power transmission device shown in FIG. 1;

FIG. 4 is a main part perspective view showing another embodiment of the magnet means constituting the power transmission device.

FIG. 5 is an enlarged sectional view showing another embodiment of the rotating element braking means constituting the power transmission device.

FIG. 6 is a schematic configuration diagram in which a power transmission device configured according to the present invention is applied to a reduction gear transmission.

FIG. 7 is a schematic configuration diagram in which a power transmission device configured according to the present invention is applied to a transmission.

[Explanation of symbols]

2: input shaft 3: output shaft 4, 4a, 4b, 4c: planetary gear mechanism 41, 41a, 41b, 41c, 41d: sun gear 42, 42a, 42b, 42c, 42d, 42e: ring gear 43, 43a, 43b, 43c 43d, 43e: planetary gears 44, 44a, 44b, 44c, 44d, 44e: planetary carrier 5: rotating element braking means 6: braking drum 7: magnet means 71: magnet support ring 711: guide groove 72: permanent magnet 73: permanent Magnet 8: Magnet actuation means 10: Device housing 11: Guide rail

Claims (3)

[Claims] An input shaft driven by the power of a prime mover, an output shaft disposed on the same axis as the input shaft,
A power transmission device comprising: a planetary gear mechanism disposed between the input shaft and the output shaft; and a braking drum made of a magnetic material connected to one of rotation elements constituting the planetary gear mechanism. Magnet means arranged on the outer peripheral side of the braking drum so as to be restricted in rotation and movable in the axial direction; and actuating the magnet means in the axial direction to provide a braking position facing the outer peripheral surface of the braking drum and the braking. And magnet actuating means positioned at a braking release position that does not face the outer peripheral surface of the drum. A power transmission device characterized by the above-mentioned. 2. An input shaft driven by the power of a prime mover, an output shaft disposed on the same axis as the input shaft,
A power transmission device comprising a plurality of planetary gear mechanisms disposed between the input shaft and the output shaft, wherein the power transmission device is connected to one of rotating elements constituting each of the plurality of planetary gear mechanisms. A braking drum made of a magnetic material; magnet means arranged on the outer peripheral side of each of the braking drums so as to be restricted in rotation and movable in the axial direction; and operating the magnet means in the axial direction to form an outer periphery of each of the braking drums. A power transmission device comprising: a braking position facing each of the surfaces; and a magnet actuating means positioned at a braking release position not facing the outer peripheral surface of each of the braking drums. 3. The power transmission device according to claim 2, wherein one of the plurality of planetary gear mechanisms includes a mechanism for reversing a rotation direction.