KR101906296B1

KR101906296B1 - Transmission connecting with servo motor and power pack having servo motor and transmission

Info

Publication number: KR101906296B1
Application number: KR1020170029411A
Authority: KR
Inventors: 오세종
Original assignee: 세종뉴텍 주식회사
Priority date: 2017-03-08
Filing date: 2017-03-08
Publication date: 2018-10-11
Also published as: KR20180102805A; WO2018164334A1

Abstract

The transmission according to the present invention includes a drive shaft connected to a servo motor, a planetary gear unit connected to the drive shaft, and a control unit for controlling the drive shaft and the planetary gear unit in a shifting position The transmission according to the present invention can precisely control the operation of the transmission using a servomotor and can perform high-output operation through shifting if necessary. And the operation stability of other industrial automation apparatuses using servo motors such as a robot driving pack, a motor cylinder, a servo press, and a nut runner can be improved by making it possible to prevent malfunction and position deviation of the apparatus during shift operation There is an effect that the efficiency can be improved.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a transmission having a servomotor and a transmission connected to a servomotor,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission connected to a servomotor, and to a power unit including a servo motor and a transmission. More particularly, the present invention relates to a transmission having a servomotor and a transmission connected to a servomotor for transmitting the power of the servomotor to an output side. To a power unit.

Power devices using servo motors are used in various devices. For example, a drive pack for a robot, a motor cylinder, a servo press, a nut runner, and the like. However, the power unit using the conventional servomotor has a fixed reduction ratio, so that it is difficult to effectively respond when a high output or high speed operation is required to be converted.

Industrial robots are usually capable of transporting objects with light weight or moving at a set speed and speed when performing low torque tasks. However, there may arise a problem that the user has to arbitrarily adjust the output of the robot every time when a relatively heavy weight item is to be transferred or when a high torque operation is required, or when another machine for additional work is required There is an inconvenience that can be.

In addition, the output may need to be adjusted while the object is being transported. If such a situation occurs, the robot must perform the output fluctuation while maintaining the previous operating state and position. Therefore, There is a possibility that a malfunction or misalignment may occur during shifting operation.

Korean Utility Model Registration No. 20-0381933, "No-load rotating structure of robot arm"

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an automatic transmission shift control apparatus and a control method thereof, which can prevent an erroneous operation or departure from a working position And a power unit having a servo motor and a transmission.

Another object of the present invention is to provide a transmission that is connected to a servo motor that transmits power during a shift operation for adjusting output or prevents a part of gears that are transmitted from becoming temporarily free to rotate .

A power unit having a servo motor and a transmission according to the present invention includes a servo motor, a drive shaft connected to the servo motor, a planetary gear unit connected to the drive shaft, A speed change gear portion for allowing the planetary gear unit to perform a speed change operation in a state in which the planetary gear unit is simultaneously set at a predetermined speed change position and an actuator for operating the speed change gear portion; A controller for controlling operations of the servo motor, the transmission, and the driving unit; and at least one position sensor for sensing a position of the speed change gear unit.
The planetary gear unit includes a sun gear provided at one end of the drive shaft, a plurality of planetary gears meshed with the outer periphery of the sun gear, a ring gear meshed with the plurality of planetary gears at the outer periphery of the plurality of planetary gears, A carrier rotatable by the planetary gears, the planetary gears being coupled to the plurality of planetary gears at the same time, and an output shaft for outputting rotational power of the carrier to the outside.
Wherein the ring gear is formed with at least one or more first engagement grooves formed on an outer circumferential surface thereof and a gear extending from the engagement portion and meshing with a plurality of the planetary gears on an inner circumferential surface thereof and having at least one or more second engagement grooves formed on an outer circumferential surface thereof And the shift gear portion may include a first engaging protrusion and a second engaging protrusion selectively engaged with the first engaging recess and the second engaging recess.
Wherein the transmission gear portion includes a first sliding portion that is key-engaged with the driving shaft and is rotatable together with the driving shaft, the first sliding portion being slidable along the driving shaft, the first sliding portion being formed with the first coupling protrusion, A second sliding part formed with a shift bar for supporting the outer periphery of the first sliding part so as to be able to rotate and move in the axial direction of the first sliding part and having the second coupling protrusion selectively engaged with the second coupling groove at the other end, .
The gap between one end of the first engaging projection and the end of the second engaging projection facing the first engaging projection is smaller than an interval between an inlet end of the first engaging groove and an inlet end of the second engaging groove .
The shift gear portion may be provided with a shift position indicating portion for indicating a shift position, and a shift position detecting sensor for detecting the position of the shift position indication portion may be provided near the shift gear portion.
The transmission connected to the servomotor according to the present invention includes a drive shaft, a planetary gear unit connected to the drive shaft, and a transmission for shifting the drive shaft and the planetary gear unit in a shifting position, A gear portion, an actuator for operating the speed change gear portion, and at least one position sensing sensor for sensing a position of the speed change gear portion.
The planetary gear unit includes a sun gear provided at one end of the drive shaft, a plurality of planetary gears meshed with the outer periphery of the sun gear, a ring gear meshed with the plurality of planetary gears at the outer periphery of the plurality of planetary gears, A carrier rotatable by the planetary gears, the planetary gears being coupled to the plurality of planetary gears at the same time, and an output shaft for outputting rotational power of the carrier to the outside.
Wherein the ring gear is formed with at least one or more first engagement grooves formed on an outer circumferential surface thereof and a gear extending from the engagement portion and meshing with a plurality of the planetary gears on an inner circumferential surface thereof and having at least one or more second engagement grooves formed on an outer circumferential surface thereof And the shift gear portion may include a first engaging protrusion and a second engaging protrusion selectively engaged with the first engaging recess and the second engaging recess.
Wherein the transmission gear portion includes a first sliding portion that is key-engaged with the driving shaft and is rotatable together with the driving shaft, the first sliding portion being slidable along the driving shaft, the first sliding portion being formed with the first coupling protrusion, A second sliding part formed with a shift bar for supporting the outer periphery of the first sliding part so as to be able to rotate and move in the axial direction of the first sliding part and having the second coupling protrusion selectively engaged with the second coupling groove at the other end, .
The gap between one end of the first engaging projection and the end of the second engaging projection facing the first engaging projection is smaller than an interval between an inlet end of the first engaging groove and an inlet end of the second engaging groove .
The shift gear portion may be provided with a shift position indicating portion for indicating a shift position, and a shift position detecting sensor for detecting the position of the shift position indication portion may be provided near the shift gear portion.

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The power transmission apparatus includes a transmission, a servomotor and a transmission connected to the servomotor according to the present invention. The power transmission apparatus includes a servomotor for precisely controlling operation of the servomotor. When necessary, It is possible to improve the operation stability and efficiency of other industrial automation devices using servo motors such as a robot driving pack, a motor cylinder, a servo press, and a nut runner .

1 is a block diagram of a power unit according to an embodiment of the present invention and including a servomotor and a transmission.
2 is a diagram showing a sectional configuration of a transmission portion in a power unit including a servo motor and a transmission according to an embodiment of the present invention.
3 is an exploded perspective view showing a main portion of a transmission according to an embodiment of the present invention.
4 is a diagram for explaining a high output operation state of the transmission according to the embodiment of the present invention.
5 is a view for explaining the shift operation of the transmission according to the embodiment of the present invention.
6 is a view for explaining a high-speed operation state of the transmission according to the embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The power transmission system including the transmission, servo motor and transmission connected to the servomotor described below can be implemented in various industrial automation devices such as a robot driving pack, a motor cylinder, a servo press, a nut runner, But can be practiced with reference to the embodiments of the present invention described below within the technical scope of the present invention.

1 is a block diagram of a power unit according to an embodiment of the present invention and including a servomotor and a transmission. 1, a power unit according to an embodiment of the present invention includes a servomotor 20, a transmission 100, and a driving unit 30, and includes a servomotor 20, a transmission 100, and a driving unit 30 (Not shown).

The control unit 10 further includes an actuator 101 for a shift operation by using signals provided from the transmission 100 from the first position sensor 103, the second position sensor 104 and the shift position sensor 106, ).

Fig. 2 is a diagram showing a cross-sectional structure of a transmission portion in a power unit including a servomotor and a transmission according to an embodiment of the present invention. Fig. 3 is a cross-sectional view illustrating a main part of a transmission according to an embodiment of the present invention. It is a perspective view.

2 is a cross-sectional view of the structure of the transmission 100. One side of the transmission 100 is axially coupled to the servo motor 20 and the other side of the transmission 100 is axially coupled to the power unit.

In the embodiment of the present invention, the power unit may be implemented as a robot drive pack, a motor cylinder, a servo press, a nut runner, etc., and the transmission 100 is coupled to a shaft that provides power to the power unit. In this embodiment, the configuration of the power unit is not described in detail. Power devices such as robot drive packs, motor cylinders, servo presses, and nut runners are commonly known in the art, and coupling such power devices to transmission 100 according to embodiments of the present invention is also well known in the art An average technician can easily perform it.

Hereinafter, the configuration of the transmission according to the embodiment of the present invention will be described in more detail with reference to FIG. 2 and FIG.

As shown in FIG. 2, the transmission 100 includes a housing 102 that forms an appearance. The drive shaft 110 is exposed to the left side of the housing 102 and is axially coupled to the servo motor 20. [ A bearing 105 is provided at a position where the drive shaft 110 passes through the housing 102.

An actuator 101 is installed at an upper portion of the housing 102. The actuator 101 includes an axis extending through the housing 102 and into the housing 102. This axis can be driven in the left and right directions in the drawing. In the embodiment of the present invention, the actuator 101 may be implemented by pneumatic, hydraulic, motor, or the like.

The planetary gear unit 120 is installed at the right end of the drive shaft 110. The planetary gear unit 120 is installed at the right end of the drive shaft 110 coupled to the servo motor 20, And a plurality of planetary gears 122 disposed around the sun gear 121. The sun gear 121 rotates together with the drive shaft 110, The planetary gears 122 are engaged with the outer periphery of the sun gear 121 at the same time.

These planetary gears 122 are mounted on the carrier 124 at equal intervals by the planetary gear support shaft 122a and each planetary gear 122 is rotatably supported by the planetary gear support shaft 122a Is installed. That is, a ball bearing or an oil-less bearing may be provided between the outer periphery of the planetary gear support shaft 122a and the inner periphery of the planetary gear 122.

A ring gear 123 is provided on the outer periphery of the planetary gears 122. The ring gear 123 includes a gear portion 123c having a gear surface which meshes with the outer periphery of the planetary gears 122 and has a gear face meshing with the planetary gear 122 on its inner periphery, And a connecting portion 123a having a diameter smaller than that of the gear portion 123c. The bearing 105 is provided at least at one or more positions in contact with the outer periphery of the drive shaft 110 of the ring gear 123.

At least one first engagement groove 123b is formed on the outer periphery of the connection portion 123a of the ring gear 123. [ Although a plurality of first coupling grooves 123b are formed in the embodiment of the present invention, at least one first coupling groove 123b may be formed in another embodiment. In the embodiment of the present invention, when the plurality of first coupling grooves 123b are formed, each of the first coupling grooves 123b may be positioned at equal intervals on the outer circumference of the coupling portion 123a.

The gear surface is formed on the inner periphery of the gear portion 123c of the ring gear 123. However, At least one second coupling groove 123d is formed on the outer periphery of the gear portion 123c at the same angular position as the first coupling groove 123b.

The first engaging groove 123b is open at its left end, and the second engaging groove 123d is open at its left and right ends. If necessary, only the right end can be opened. The opening ends of the fastening protrusions to be described later enter and are fastened in directions opposite to each other.

Next, a speed change gear portion 140 for shifting operation is provided on the outer side of the planetary gear portion 120. The transmission gear portion 140 includes a first sliding portion 141 which is engaged with and disconnected from the connecting portion 123a of the ring gear 123 and is engaged with and separated from the gear portion 123c of the ring gear 123 And the second sliding portion 142 is formed. The second sliding portion 142 is connected to the actuator 101 and receives power from the actuator 101 to linearly move.

The first sliding portion 141 of the speed change gear portion 140 is formed in a substantially cylindrical shape and inserted into the outer periphery of the drive shaft 110, And a key groove 141a to be engaged with the key projection 111 is formed on the inner peripheral surface. Therefore, the first sliding portion 141 is slidable along the longitudinal direction of the driving shaft 110, and is always rotated together with the driving shaft 110.

A circular annular support groove 141b extending along the outer circumference is formed on an outer circumferential surface of the first sliding portion 141. The inner circumference of the first sliding portion 141 is formed with a left side portion in which the above- And the right side portion has an inner diameter that is larger than the left side portion and is provided in a stepped shape. At least the first engaging projection 141c is formed in this stepped portion. The first coupling protrusion 141c is engaged with the first coupling groove 123b provided in the coupling portion 123a of the ring gear 123 when performing the shifting operation. That is, the first coupling protrusion 141c is fastened or separated from the first coupling groove 123b by the sliding operation of the first sliding portion 141 in the left-right direction.

Next, the second sliding portion 142 is slidably supported by the actuator 101 in the left-right direction in a state where the second sliding portion 142 is pivotally supported by the support shaft 142a having both ends supported inside the housing 102 so as to be slidable in the left- . And a shift bar 142b extending downward toward the first sliding portion 141 and partially inserted into the support groove 141b of the first sliding portion 141 is provided at the left end of the second sliding portion 142 . The end of the shift bar 142b is bent so as to bend to both sides and is formed so that each end of the shift bar 142b is partially inserted into both sides of the support groove 141b.

A second coupling protrusion 142c protruding downward is formed at the right end of the second sliding portion 142. [ The second engagement protrusion 142c is engaged with or separated from the second engagement recess 123d by driving the second sliding portion 142 in the left and right directions.

A first position detecting sensor 103 and a second position detecting sensor 104 are installed on the outer sides of the left and right sides of the second sliding portion 142. The first position sensing sensor 103 and the second position sensing sensor 104 sense the operation position of the second sliding portion 142 and transmit a signal of the operation state to the control portion 10.

The distance D2 between the right end of the first engaging projection 141c and the left end facing the first engaging projection 141c of the second engaging projection 142c is smaller than the distance between the entrance end of the first engaging projection 123c 2 is smaller than the distance D1 between the inlet ends 123d of the two coupling grooves. That is, "D1 > D2" (see Fig. 5). The planetary gear unit 140 always supports the planetary gear unit 120 through the first engagement groove 123b or the second engagement groove 123d so that the planetary gear unit 120 and the drive shaft 110 are engaged with the speed change gear unit 140 In a state of being free to rotate during an operation for shifting of the vehicle.

On the other hand, a shift position detecting sensor 106 may be provided for determining an accurate shift position for a shift operation. In the embodiment of the present invention, the shift position detecting sensor 106 may be installed at the lower portion of the housing 102 so as to accurately determine the position of the first engagement groove 123b. A separate shift position indicator 141d may be formed on the outer periphery of the connection portion 123a for the purpose of position identification by sensing the shift position sensor 106. [ The shift position detection sensor 106 may be implemented by a proximity sensor or an optical sensor, and the shift position indication section 141d may be implemented by a groove, a projection, or a light receiving sensor.

In order to determine the shift position, the angle detecting function of the servo motor 20 and the encoder can be used without using the above-described shift position detecting sensor 106. [ The encoder of the servo motor 20 can be used for detecting the angular data within one rotation and detecting the amount of movement at the origin according to the operation of the transmission 100. [ Therefore, the accurate position of the first coupling groove 123b can be sensed by using the encoder.

Hereinafter, the operation of the transmission, the servomotor, and the power unit including the transmission will be described in connection with the servo motor according to the embodiment of the present invention.

4 is a view for explaining a high output operation state of the transmission according to the embodiment of the present invention. FIG. 5 is a view for explaining the shifting operation of the transmission according to the embodiment of the present invention, and FIG. Speed operating state of the transmission according to the example.

The initial state of the power unit according to the embodiment of the present invention may be any one of the states of high-speed operation, high-output operation, or shifting operation of the transmission for shifting.

First, as shown in FIG. 4, the high output operation state of the transmission 100 according to the embodiment of the present invention will be described. In the embodiment of the present invention, the high output state is an operation in which the transmission 100 decelerates the speed provided by the servomotor 20 to exert a high output torque.

To this end, the actuator 101 moves the transmission gear portion 140 to the left in the drawing. Accordingly, the first sliding portion 141 slides to the left along the driving shaft 110, so that the first coupling protrusion 141c and the first coupling groove 123b are separated from each other. The second engaging protrusion 142c of the second sliding portion 142 is inserted into the second engaging groove 123d of the ring gear 123. At this time, the controller 10 can recognize that the high power mode state is ready according to the position of the second sliding portion 142 sensed by the first position sensing sensor 103 and the second position sensing sensor 104.

In this state, when the power is transmitted to the driving shaft 110 through the servo motor 20, the first sliding portion 142 rotates together with the driving shaft 110. However, since the second engagement protrusion 142c and the second engagement recess 123d are engaged with each other, the ring gear 123 is restrained from rotating.

The rotational power of the drive shaft 110 is transmitted to the plurality of planetary gears 122 through the sun gear 121 and the planetary gears 122 rotate to revolve around the sun gear 121, The carrier 124 rotates at a rotational speed smaller than the rotational speed of the sun gear 121. The output shaft 130 rotates due to the rotation of the carrier 124 and the rotation speed of the drive shaft 110 is reduced and transmitted through the planetary gear unit 120 so that high output power transmission is achieved by relatively high torque.

On the other hand, when high-speed operation is required after high output power transmission, the shift gear unit 140 proceeds to shift. 5 is a view for explaining the shift operation of the transmission according to the embodiment of the present invention.

As shown in FIG. 5, the transmission gear portion 140 is slidably operated by the actuator 101 in order to progress the shift. The first engaging projection 141c and the second engaging projection 142c of the speed change gear portion 140 are engaged with the first engaging recess 123b and the second engaging recess 123d of the planetary gear portion 120 at the same time Thereby simultaneously restricting the planetary gear unit 120 and the shift gear unit 140.

Therefore, even if a considerable load is applied to the drive unit or an external force is applied, the drive shaft 110 and the output shaft 130 remain fixed so as not to rotate. Therefore, it is possible to maintain the stable position of the driving apparatus even if the shifting is performed during the operation.

This state is such that the distance D2 between the right end of the first engaging projection 141c and the left end facing the first engaging projection 141c of the second engaging projection 142c is smaller than the distance between the entrance end of the first engaging projection 123b Is smaller than the interval (D1) between the inlet ends (123d) of the second coupling grooves.

Therefore, when the transmission gear portion 140 slides, any one of the first coupling protrusion 141c and the first coupling groove 123b or the second coupling protrusion 142c and the second coupling groove 123d is always engaged Lt; / RTI > If the first coupling protrusion 141c and the first coupling groove 123b and the second coupling protrusions 142c and the second defect groove 123d are disengaged from each other, the drive shaft 110 and the output shaft 130 An external load or an external force applied to the output shaft 130 may be transmitted directly to cause the drive apparatus to idle. The first engaging protrusion 141c and the first engaging recess 123b and the second engaging protrusion 142c and the second engaging recess 123d are always engaged with each other as in the embodiment of the present invention, So that it can be performed stably.

The sensing of the position of the first engagement groove 123b and the second engagement groove 123d for shifting is determined by sensing the position of the shift position instruction portion 141d of the planetary gear unit 120 by the shift position detection sensor 106 For this purpose, the shift position indication portion 141d may be formed on the same axis as the position where the first engagement groove 123b is installed, if necessary. Accordingly, when it is determined that the shift is necessary in the control unit 10 and the shift position indication sensor 141d is first sensed by the shift position indication unit 141d, the shift position can be determined by determining that the position is the shift position. In another embodiment, the synchronous position can be found using the pulse signal generated by the encoder of the servo motor 20, and the synchronous position can be found by periodically searching for the origin position.

After the shifting is completed, high-speed output is performed. 6 is a view for explaining a high-speed operation state of the transmission according to the embodiment of the present invention.

6, when the transmission gear portion 140 is moved to the right end by the actuator 101 in a high output state, the first engaging projection 141c is engaged with the first engaging groove 123b to engage with the first sliding portion 141 and the connecting portion 123a of the planetary gear unit 120 are engaged. The second engaging projection 142c is completely separated from the second engaging recess 123d and consequently the ring gear 123 of the planetary gear unit 120 is rotatable together with the drive shaft 110. [ When the first position sensing sensor 103 and the second position sensing sensor 104 sense the position of the second sliding portion 142, the controller 10 determines that the shift to the high speed output state is completed And transmits a high-speed output command to the servo motor 20. [

In this high-speed output operation, when the driving shaft 110 rotates, the first sliding portion 141 of the transmission gear portion 140 rotates together with the driving shaft 110, and the planetary gear portion 120 rotates together with the first sliding portion 141, The planetary gear unit 120 rotates together with the drive shaft 110 so that the power of the drive shaft 110 is output to the output shaft 130 at a ratio of 1 to 1 so that the rotation speed of the planetary gear unit 120 Power. That is, the high-speed output operation causes the output speed of the servo motor 20 to be transmitted to the output shaft 130 as it is.

The power transmission apparatus including the transmission, the servomotor and the transmission connected to the servo motor according to the embodiment of the present invention can precisely control operation using a servo motor and can perform a shift and a high output operation when necessary.

In addition, it is possible to prevent malfunction and position deviation from occurring during deceleration and high output operation for controlling the output, so that it is used in a robot driving pack, a motor cylinder, a servo press, a nut runner, etc. to perform a stable and effective automation operation .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Embodiments are possible. Accordingly, the technical scope of the present invention should be determined by the appended claims.

100 ... transmission
101 .. Actuator
110 ... drive shaft
111 ... key projection
120 ... planetary fisherman
140:

Claims

Servo motor;
A planetary gear unit that is connected to the drive shaft; and a control unit that controls the planetary gear unit so that a shift operation is performed in a state in which the drive shaft and the planetary gear unit are positioned at the simultaneously set shift positions, A transmission mechanism including a speed change gear portion and an actuator for operating the speed change gear portion;
A drive unit for receiving power from the servo motor via the transmission;
A controller for controlling operations of the servo motor, the transmission, and the driving unit;
And at least one position sensing sensor for sensing a position of the speed change gear portion, and a power transmission.

The planetary gear unit according to claim 1, wherein the planetary gear unit comprises: a sun gear provided at one end of the drive shaft; a plurality of planetary gears meshed with the outer periphery of the sun gear; And a transmission including a plurality of planetary gears simultaneously engaged with each other, a carrier rotated by the planetary gears, and an output shaft for outputting rotational power of the carrier to the outside.

3. The planetary gear set according to claim 2, wherein the ring gear comprises: a connecting portion having at least one or more first engaging grooves formed on an outer circumferential surface; a gear extending from the connecting portion and meshing with a plurality of the planetary gears on an inner circumferential surface; And a gear portion having a second coupling groove formed therein,
And the transmission gear portion has a first coupling protrusion and a second coupling protrusion selectively engaged with the first coupling groove and the second coupling groove, and a transmission.

The transmission according to claim 3, wherein the shift gear portion includes: a first sliding portion that is key-engaged with the driving shaft and rotatable together with the driving shaft, the first sliding portion being slidable along the driving shaft,
A shift bar that is pivotally supported in parallel with the drive shaft and supports the outer periphery of the first sliding portion so that the first sliding portion can be rotated and moved in the axial direction and the other end of the shift bar is selectively engaged with the second engagement groove, And a second sliding portion formed with a second coupling protrusion, and a power transmission.

5. The connector according to claim 4, wherein an interval between one end of the first engaging projection and an end of the second engaging projection facing the first engaging projection is larger than a distance between an inlet end of the first engaging groove and an inlet end of the second engaging groove And a power transmission mechanism having a servo motor and a transmission.

The transmission according to claim 1, wherein the transmission gear portion is provided with a shift position indicating portion for indicating a shift position, and a gear position sensor for detecting the position of the shift position indication portion is provided in the vicinity of the shift gear portion, The power unit has.

A drive shaft;
A planetary gear unit connected to the drive shaft;
A shift gear portion for shifting the gear to a state in which the drive shaft and the planetary gear portion are simultaneously positioned at a shifting position that is set at the time of shifting operation;
An actuator for operating the transmission gear portion;
And at least one position sensor for sensing a position of the shift gear unit.

The planetary gear unit according to claim 7, wherein the planetary gear unit comprises: a sun gear provided at one end of the drive shaft; a plurality of planetary gears meshing with the outer periphery of the sun gear; A plurality of planetary gears coupled together and connected to a servo motor having a carrier rotating by the planetary gears and an output shaft for outputting rotational power of the carrier to the outside.

9. The planetary gear set according to claim 8, wherein the ring gear comprises: a connecting portion having at least one or more first engaging grooves formed on an outer circumferential surface thereof; a gear extending from the connecting portion and meshing with a plurality of the planetary gears on an inner circumferential surface thereof; And a gear portion having a second coupling groove formed therein,
And the transmission gear portion is connected to a servo motor having a first coupling protrusion and a second coupling protrusion selectively engaged with the first coupling groove and the second coupling groove.

10. The shift control apparatus according to claim 9, wherein the shift gear portion comprises: a first sliding portion that is key-engaged with the drive shaft and is rotatable together with the drive shaft, the first sliding portion being slidable along the drive shaft,
A shift bar that is pivotally supported in parallel with the drive shaft and supports the outer periphery of the first sliding portion so that the first sliding portion can be rotated and moved in the axial direction and the other end of the shift bar is selectively engaged with the second engagement groove, And a second sliding portion formed with a second coupling protrusion.

12. The apparatus of claim 10, wherein a distance between one end of the first engaging projection and an end of the second engaging projection facing the first engaging projection is larger than a distance between an inlet end of the first engaging groove and an inlet end of the second engaging groove And is connected to a servomotor provided so as to be smaller than an interval.

The transmission according to claim 7, wherein the transmission gear portion is provided with a shift position indicating portion for indicating a shift position, and is connected to a servo motor provided with a shift position detecting sensor for sensing the position of the shift position indication portion near the shift gear portion Transmission.

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