JP2010005783A - Electric rotary joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric rotary joint which can efficiently cool motors with a speed reducer despite of a small space and can also efficiently cool driver devices disposed around the respective motors with a speed reducer. <P>SOLUTION: An electric motor 4 comprises a driver device 50 for regulating the rotation of a rotating shaft of the electric motor 4. At least a part of the driver device 50 is housed in any one of a first frame 2 and a second frame. A cooling path for cooling the electric motor 4 is provided in a joint part 15 and the first frame 2 or the second frame. An axial flow fan 70 is provided along the cooling path. At least a part of the driver device 50 is disposed on the air suction side of the axial flow fan 70. The electric motor 4 is disposed on the air ejection side of the axial flow fan 70. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electric rotary joint that rotatably connects two frames.

For example, an articulated industrial robot, a biped walking type mobile robot, and the like are provided with a motor with a speed reducer at a joint that rotatably connects one frame and the other frame, The frame is rotatably connected via a motor with a speed reducer.
Here, this type of robot is often equipped with a control CPU and a motor drive circuit (driver device) for controlling the drive of the motor with a speed reducer. Since these control CPUs and motor drive circuits are vulnerable to heat, a frame forming the outer shape of the robot, for example, the control CPUs and motor drive circuits are centrally arranged in the body part, and intake ports for taking air into the body part There is a case where an exhaust port for radiating heat in the body part is provided.

  In addition, considering the case where the robot is operated outdoors in the body part where the control CPU and motor drive circuit are centrally arranged, the outer surface of the body part is divided into a part that is easily exposed to direct sunlight and a part that is not easily exposed to direct sunlight. A technique is proposed that separates the color or surface treatment method. As a result, damage to the control CPU and motor drive circuit due to heat is efficiently prevented (see, for example, Patent Document 1).

JP 2006-116630 A

  However, the above-described conventional technology does not disclose any technology for efficiently cooling a motor with a reduction gear mounted on a joint portion. For this reason, there exists a subject that a motor with a reduction gear may become high temperature, motor efficiency may fall, or a motor with a reduction gear may be damaged by heat.

Moreover, since the motor with a reduction gear forms a joint part, it is necessary to install the motor with a reduction gear in a space-saving manner. For this reason, there is a problem that it is difficult to forcibly cool the motor with a reduction gear.
Furthermore, since the control CPU and the motor drive circuit are centrally arranged on the body part, there is a problem that the body part is enlarged.

  Therefore, the present invention has been made in view of the above-described circumstances, and can efficiently cool a motor with a speed reducer while saving space, and a driver while arranging each driver device in the vicinity of each motor with a speed reducer. The apparatus also provides an electric rotary joint that can be efficiently cooled.

In order to solve the above-described problem, the invention described in claim 1 is provided with a motor with a speed reducer at a joint portion connecting one frame and the other frame, and the one frame and the other frame are connected to each other. In the electric rotary joint that is rotatably connected via the motor with a speed reducer, the motor with the speed reducer has a driver device for performing rotation control of the rotating shaft, and at least a part of the driver device is provided. Built in either the one frame or the other frame, and provided with a cooling passage for cooling the motor with a speed reducer in the joint portion and the one frame or the other frame. A blower fan is provided in the middle of the cooling passage, at least a part of the driver device is disposed on the air suction side of the blower fan, and the motor with a speed reducer Characterized in that arranged on the air discharge side of the serial blower fan.
By comprising in this way, a driver apparatus and a motor with a reduction gear can be forcedly cooled with one ventilation fan, utilizing the empty space inside a flame | frame effectively.
Moreover, since the motor with a speed reducer that generates heat more easily than the driver device is disposed on the air discharge side of the blower fan, the driver device is disposed on the air suction side of the blower fan. And fresh air can be applied to the driver device without stagnation.

In the invention described in claim 2, the one frame and the casing of the motor with a speed reducer are integrally formed, the other frame and the speed reducer of the motor with a speed reducer are linked, the blower fan, and At least a part of the driver device is built in the one frame.
Thus, by integrally molding the casing of the motor with a speed reducer and one frame, the heat radiation area of the entire motor with the speed reducer can be increased.
Further, by incorporating at least part of the blower fan and the driver device in one frame, it is possible to reduce the size of the entire rotary electric joint.

The invention described in claim 3 is characterized in that a plurality of fins are provided along the air flow in the cooling passage, and the plurality of fins are integrally formed with at least the casing of the motor with a reduction gear.
By comprising in this way, the thermal radiation area of the whole motor with a reduction gear can be increased further.

According to a fourth aspect of the present invention, the driver device includes a motor drive circuit board on which switching elements constituting a bridge circuit are mounted, and a power supply circuit board that supplies current to the motor drive circuit board and includes a smoothing capacitor. The motor drive circuit board is arranged on the motor side with a speed reducer, and the power circuit board is arranged on the air suction side of the blower fan.
In this way, by dividing the driver device, the layout of the driver device can be improved, so that the free space can be used effectively.
Also, by arranging the motor drive circuit board on the motor side with a speed reducer, the heat generated by the motor drive circuit board can be dissipated through the frame, and the power circuit board is arranged on the air suction side of the blower fan. Thus, the power supply circuit board can be forcibly cooled using a blower fan.

The invention described in claim 5 is characterized in that the blower fan is an axial fan.
With this configuration, the thickness direction of the blower fan can be reduced.

According to a sixth aspect of the present invention, at least two frames are rotatably connected via a joint portion, a motor with a speed reducer is provided in one of the frames, and the motor with a speed reducer is annular. The rotor, a rotor rotatably provided on the radially inner side of the stator, a reduction mechanism provided on one end side of the rotor, which decelerates and outputs the rotation speed of the rotation shaft of the rotor, and the rotation shaft An electric rotary joint that rotates the other frame about the joint portion by connecting the speed reduction mechanism and another frame of the frames. A cooling passage for cooling the motor with a speed reducer is provided in the one frame, and a casing for fixing the stator is integrally formed in the middle of the cooling passage. Both of the driver devices are arranged, at least one part of the cooling passage is provided with a blower fan, and the blower fan is arranged with the air discharge side facing the cooling passage. To do.
By comprising in this way, a driver apparatus and a motor with a reduction gear can be forcedly cooled with one ventilation fan, utilizing the empty space inside a flame | frame effectively. Further, by integrally molding the motor housing on the frame, the heat radiation area of the motor with a reduction gear can be increased.

According to a seventh aspect of the present invention, the stator includes a cylindrical stator iron core that is fitted and fixed to the casing, and a plurality of teeth portions that project radially inward from the stator iron core. The teeth portion is composed of a main pole arranged at equal intervals in the circumferential direction and wound with a coil, and an auxiliary pole arranged between the main poles and not wound with the coil. These coils and a heat conducting member in contact with the auxiliary electrode are interposed in the gap with the auxiliary electrode.
By comprising in this way, the heat which arises from a coil can be transmitted also to an auxiliary pole via a heat transfer member other than a main pole.

According to an eighth aspect of the present invention, a heat sink is provided in the casing, and the heat sink includes a base portion that is in contact with the casing and a plurality of fins that are formed so as to rise from the base portion and are arranged in parallel. , At least a part of the driver device is disposed on the tip side of the plurality of fins, and a passage formed by the base portion, the plurality of fins, and at least a part of the driver device is configured as the cooling passage. It is characterized by.
By comprising in this way, the thermal radiation area of the motor with a reduction gear and a driver apparatus can be enlarged further. Further, it is possible to reliably wind the driver device.

According to the first aspect of the present invention, the driver device and the motor with a speed reducer can be forcibly cooled with one blower fan while effectively utilizing the empty space inside the frame.
Moreover, since the motor with a speed reducer that generates heat more easily than the driver device is disposed on the air discharge side of the blower fan, the driver device is disposed on the air suction side of the blower fan. And fresh air can be applied to the driver device without stagnation.
For this reason, the motor with a reduction gear can be efficiently cooled while saving space, and the driver device can also be efficiently cooled while arranging the driver device in the vicinity of the motor with the reduction gear.

According to the second aspect of the present invention, the heat radiation area of the entire motor with a speed reducer can be increased by integrally forming the casing of the motor with the speed reducer and the one frame. For this reason, the motor with a reduction gear can be cooled more efficiently.
Further, by incorporating at least part of the blower fan and the driver device in one frame, it is possible to reduce the size of the entire rotary electric joint.

  According to the third aspect of the present invention, the heat radiation area of the entire motor with a speed reducer can be further increased, and the motor with a speed reducer can be cooled more efficiently.

According to the invention described in claim 4, since the layout of the driver device can be improved by dividing the driver device, an empty space can be used effectively, and the rotary electric joint can be further downsized. It becomes possible.
Also, by arranging the motor drive circuit board on the motor side with a speed reducer, the heat generated by the motor drive circuit board can be dissipated through the frame, and the power circuit board is arranged on the air suction side of the blower fan. Thus, the power supply circuit board can be forcibly cooled using a blower fan. For this reason, it becomes possible to cool a driver apparatus efficiently.

  According to the invention described in claim 5, the thickness direction of the blower fan can be reduced, and the rotary electric joint can be further downsized.

  According to the sixth aspect of the present invention, the driver device and the motor with a speed reducer can be forcibly cooled with one blower fan while effectively utilizing the empty space inside the frame. Further, by integrally molding the motor housing on the frame, the heat radiation area of the motor with a reduction gear can be increased. For this reason, it becomes possible to cool the motor with a reduction gear and the driver device efficiently while saving space.

  According to the seventh aspect of the present invention, the heat generated from the coil can be transmitted to the auxiliary pole through the heat transfer member in addition to the main pole. For this reason, a sufficient heat transfer path can be secured from the coil to the motor housing, and the motor with a reduction gear can be cooled more efficiently.

  According to the eighth aspect of the present invention, the heat radiation area of the motor with a reduction gear and the driver device can be further increased. Further, it is possible to reliably wind the driver device. For this reason, it becomes possible to cool a motor with a reduction gear and a driver device more efficiently.

It is a perspective view of the electric rotary joint in 1st embodiment of this invention. It is a perspective view of the state where the 2nd frame of the electric rotary joint in a first embodiment of the present invention was removed. It is a section perspective view of the electric rotary joint in a first embodiment of the present invention. It is a perspective view of the state where the 2nd frame of the electric rotary joint in a first embodiment of the present invention was removed. It is a top view of the axial fan in a first embodiment of the present invention. It is sectional drawing of the reduction gear in embodiment of this invention. It is explanatory drawing which shows the flow of the air in 1st embodiment of this invention. It is explanatory drawing which shows the flow of the air in 1st embodiment of this invention. It is a perspective view of the electric rotary joint in 2nd embodiment of this invention. It is a perspective view of the 1st frame in the second embodiment of the present invention. It is sectional drawing which follows the AA line of FIG. It is the B section enlarged view of FIG. It is a top view of the electric rotary joint in the second embodiment of the present invention. It is a side view of the electric rotary joint in 2nd embodiment of this invention. It is operation | movement explanatory drawing of the electric rotary joint in 2nd embodiment of this invention. It is a side view of the electric rotary joint of other embodiments in the second embodiment of the present invention. It is operation | movement explanatory drawing of the electric rotary joint of other embodiment in 2nd embodiment of this invention.

Next, a first embodiment of the present invention will be described with reference to FIGS. In the following drawings, for the convenience of explanation, the direction of the electric rotary joint 1 is appropriately changed so that the most visible portion appears.
As shown in FIGS. 1 to 3, the electric rotary joint 1 is used, for example, in a joint portion of an industrial robot such as an articulated robot, and connects the first frame 2 and the second frame 3. An electric motor 4 and a speed reducer 6 constituting a motor with a speed reducer are provided in the joint portion 15 to be performed. And the 1st frame 2 and the 2nd frame 3 are connected via the electric motor 4 and the reduction gear 6 so that rotation is possible.
The first frame 2 and the second frame 3 are formed in a rectangular tube shape. The first frame 2 and the second frame 3 are arranged on the same straight line, and are rotated around an axis J intersecting the straight line.

The electric motor 4 is disposed such that the axis of the rotating shaft 5 coincides with the axis J, and a speed reducer 6 is attached to the rotating shaft 5.
The electric motor 4 includes a front bracket 7, a rear bracket 8, a stator 10 fixed to the inside of the front bracket 7 and the rear bracket 8, and a rotor that is rotatably provided inside the stator 10 in the radial direction. 11. In addition, a motor drive circuit board 51 constituting a driver device 50 for driving the electric motor 4 is arranged inside the front bracket 7, and an encoder for detecting the rotation angle of the rotary shaft 5 inside the rear bracket 8. 40 is disposed.

The front bracket 7 is formed in a bottomed cylindrical shape and is integrally formed with the first frame 2.
That is, a part of the first frame 2 serves as the front bracket 7. Between the peripheral wall 12 of the front bracket 7 and the end face 2a of the first frame 2 on the electric motor 4 side, a plurality of fins 81 are erected along a direction substantially perpendicular to the axis J. The fins 81 are formed along the peripheral wall 12 of the front bracket 7 from the position corresponding to the axis J to the end surface 2a of the first frame 2, and have a substantially triangular shape in an axial plan view. The fins 81 are integrated with the peripheral wall 12 of the front bracket 7 and the first frame 2.

A bearing 14 that rotatably supports one end side of the rotary shaft 5 is provided at the center in the radial direction of the front bracket 7.
In this way, by integrally molding the first frame 2 and the front bracket 7, the front bracket 7 can be configured by a part of the first frame 2. That is, the first frame 2 can have a function of holding the stator 10 and the rotating shaft 5.

On the other hand, the rear bracket 8 is made of aluminum and has a bottomed cylindrical shape, and is provided so as to close the opening of the front bracket 7. A bearing 17 that rotatably supports the rear side of the rotary shaft 5 is provided at the center in the radial direction of the rear bracket 8.
The outer peripheral portion of the stator 10 is inserted and fixed to the peripheral wall 18 of the rear bracket 8 on the opening side. That is, the stator 10 is in a state of being fitted and fixed to the front bracket 7 and the rear bracket 8 respectively. The axial lengths of the peripheral walls 12 and 18 of the front bracket 7 and the rear bracket 8 are set such that a gap cannot be formed when the stator 10 is housed in the brackets 7 and 8. . Thereby, it is possible to prevent dust from entering from the mating surface of the front bracket 7 and the rear bracket 8.

The stator 10 is formed by laminating magnetic metal plates in the axial direction or pressurizing soft magnetic powder, and has a substantially cylindrical stator core 21. The outer periphery of the stator iron core 21 is inserted into the front bracket 7 and the rear bracket 8.
On the inner peripheral side of the stator core 21, a plurality of teeth (not shown) project radially inward, and a plurality of coils (not shown) are wound through insulators 22 that are insulating materials. Has been.

  Each terminal portion of the coil is connected to a motor drive circuit board 51 of the driver device 50 via a terminal 24 such as a pin header. The driver device 50 is configured by dividing a motor drive circuit board 51 formed in a substantially annular shape and a power supply circuit board 52 formed in a substantially rectangular shape in plan view. Is electrically connected.

  In the driver device 50, the motor drive circuit board 51 of the two circuit boards 51 and 52 is disposed inside the front bracket 7, and the power circuit board 52 is disposed in the first frame 2. . Therefore, the motor drive circuit board 51 is set such that the diameter of the hole formed in the center is set to a size allowing the rotation shaft 5 to be inserted, and the outer diameter is set smaller than the inner diameter of the peripheral wall 12 of the front bracket 7. ing. On the other hand, the outer shape of the power circuit board 52 is set to a size that can be accommodated in an empty space in the first frame 2.

The motor drive circuit board 51 switches the energization to each coil 23. A plurality of switching elements 48 are mounted on the surface opposite to the stator 10, and the switching elements 48 are turned on / off. A pre-drive circuit (not shown) to be controlled is mounted.
The switching element 48 connects a transistor such as a field effect transistor (FET) and a diode that prevents reverse flow between the drain and source of the FET (transistor) in parallel to a motor drive power supply (not shown). It has the structure. A bare chip is used as the FET, and the space occupied by the FET is reduced by resin molding the bare chip. The switching element 48 forms an H bridge circuit for each phase, and the current supplied to each coil (not shown) is switched for each phase by switching each on / off.

  A heat dissipation sheet 46 is provided on the switching element 48 mounted on the motor drive circuit board 51. The heat dissipation sheet 46 is formed in a substantially annular shape so as to correspond to the location where the switching element 48 is disposed. The motor drive circuit board 51 is fixed to the front bracket 7 via the heat dissipation sheet 46.

The power supply circuit board 52 is for supplying a current to the motor drive circuit board 51, and is composed of two boards 52a and 52b, both of which are fixed by stud bolts 49.
On one substrate 52a of the power supply circuit substrate 52, an aluminum electrolytic capacitor 58 for smoothing the power supply, a lead wire 53, a connector portion 55 for connecting a flexible substrate 54 described later, and the like are mounted. The aluminum electrolytic capacitor 58 is connected to a motor drive power supply (not shown), and is a circuit for smoothing the pulsating current contained in the rectified current to a state closer to direct current. As a result, a smoothed current can be supplied to the H bridge circuit of the motor drive circuit board 51.

  The other substrate 52b of the power circuit board 52 is fixed to a mounting base 47 provided on the inner side of the first frame 2, and the entire power circuit board 52 is positioned substantially in the center in the longitudinal direction in the first frame 2. It is supposed to be.

Here, as shown in FIGS. 2, 4, and 5, an axial fan 70 is provided on the end surface 2 a of the first frame 2 on the electric motor 4 side. The axial fan 70 is disposed with the air suction side 70a facing the power supply circuit board 52 side and the air discharge side 70b facing the electric motor 4 side. That is, the first frame 2 is centered on the axial fan 70 and has a static pressure on the power circuit board 52 side and a dynamic pressure on the electric motor 4 side.
The axial fan 70 surrounds a fan boss 71 rotatably supported at the center in the axial direction, a plurality of fan blades 72 integrally formed on the outer peripheral surface of the fan boss 71, and the periphery of the fan blade 72. The fan shroud 73 is formed.

The fan shroud 73 includes a cylindrical portion 73a disposed around the fan blade 72 and a skirt portion 73b formed so as to expand from the end of the cylindrical portion 73a toward the inner wall of the first frame 2 from the electric motor 4 side end. ing.
An opening 79 corresponding to the cylindrical portion 73 a of the fan shroud 73 is formed on the end surface 2 a on the electric motor 4 side of the first frame 2. As a result, the air inside the first frame 2 is sucked into the axial fan 70 and discharged to the electric motor 4 through the opening 79.

That is, a cooling passage 74 for cooling the electric motor 4 is provided from the first frame 2 to the joint portion 15 where the first frame 2 and the second frame 3 are connected. . Therefore, the axial fan 70 is disposed in the middle of the cooling passage 74.
Here, the plurality of fins 81 provided between the peripheral wall 12 of the front bracket 7 and the end surface 2a of the first frame 2 on the electric motor 4 side are erected along a direction substantially orthogonal to the axis J. Therefore, it is provided so as to follow the flow of air blown by the axial flow fan 70. For this reason, the air flow is not blocked by the plurality of fins 81.

As shown in FIGS. 2 and 3, the rotor 11 includes a rotary shaft 5 formed in a hollow shape, and a cylindrical ring magnet (not shown) that is externally fitted and fixed to the rotary shaft 5. . The ring magnet is magnetized so that the magnetic poles change in order in the circumferential direction.
Under such a configuration, when a current flows through a coil (not shown) wound around the stator 10, a magnetic field is formed, and a magnetic attractive force or a repulsive force generated between the magnetic field and the ring magnet is generated. The rotating shaft 5 rotates.

  The other end of the rotating shaft 5 protrudes from the rear bracket 8, and a sensor magnet 28 is provided here via an attachment member 29. The sensor magnet 28 constitutes one of the encoders 40 for detecting the rotation angle of the rotary shaft 5 and is magnetized in two poles. The mounting member 29 is formed by integrally molding a cylindrical portion 29a that is externally fitted and fixed to the rotary shaft 5 and an outer flange portion 29b that is provided at the outer end of the cylindrical portion 29a. The outer flange portion 29b is for positioning the sensor magnet 28 in the axial direction. The sensor magnet 28 is fixed such that one end surface thereof is in contact with the outer flange portion 29b.

On the outer side in the axial direction of the rear bracket 8, a substantially annular encoder substrate 30 is disposed inward of the sensor magnet 28 in the axial direction. The encoder board 30 is fastened and fixed to the rear bracket 8 by a bolt 32 via a collar 31.
The encoder board 30 constitutes the other side of the encoder 40. On the encoder board 30, four Hall elements 41 are mounted, and a rotation angle detection circuit (not shown) is mounted. .

  The hall elements 41 are arranged at 90 ° intervals on the circumference centering on the rotation axis of the rotor 11 at positions facing the sensor magnets 28 on the encoder substrate 30. The Hall element 41 detects a change in the magnetic field generated from the sensor magnet 28 as position information of the rotation shaft 5 and outputs a signal having a predetermined waveform to the rotation angle detection circuit. The rotation angle detection circuit detects the rotation angle of the rotation shaft 5 based on the output signal from the hall element 41.

  The encoder board 30 is electrically connected to the motor drive circuit board 51 of the driver device 50 via the flexible board 54. That is, the Hall element 41 and the rotation angle detection circuit can be driven by supplying the power of the driver device 50 to the encoder board 30, and the rotation angle position information of the rotary shaft 5 on the encoder board 30 is output to the driver device 50. You can also

One end of the rotary shaft 5 is in a state of protruding outward in the axial direction via the motor drive circuit board 51 of the driver device 50, the heat dissipation sheet 46, and the front bracket 7. A speed reducer 6 is attached to one end of the rotating shaft 5 protruding.
As shown in FIGS. 3 and 6, the speed reducer 6 is obtained by integrating a cross roller bearing 61 and a harmonic drive (registered trademark) that can receive loads in both the thrust direction and the radial direction. That is, the speed reducer 6 includes a wave generator 62 that is externally fitted and fixed to the rotary shaft 5, and a flex spline 63 that is disposed on the outer periphery of the wave generator 62. Is arranged. The inner ring (inner race) 61a of the cross roller bearing 61 also serves as a circular spline 64 of Harmonic Drive (registered trademark).

  The wave generator 62 includes a cam 65 having an elliptical shape in plan view and a ball bearing 66 provided on the outer periphery thereof. A shaft hole 67 for connecting the rotary shaft 5 and the cam 65 is formed at the center in the radial direction of the cam 65, whereby the rotary shaft 5 and the cam 65 rotate together.

A flex spline 63 provided on the outer peripheral surface of the ball bearing 66 of the wave generator 62 is an elastic gear, and has a cylindrical gear main body 68 and an outer flange portion 69 integrally formed at the outer end of the gear main body 68. It consists of and.
The gear body 68 is deformed into an ellipse by the wave generator 62, and the inner peripheral surface is formed to be slidable with the wave generator 62. A tooth portion 78 is formed on the outer peripheral surface of the gear body 68.

  In the outer flange portion 69 of the flex spline 63, a thick portion 77 is formed on the entire outer periphery. The radial width of the thick portion 77 is set so as to substantially match the radial width of the outer ring (outer race) 61 b of the cross roller bearing 61. The thick portion 77 has a plurality of bolt holes (not shown). The bolts 76 are screwed into the bolt holes so that the outer flange portion 69 and the second frame 3 are fastened together with the outer ring (outer race) 61 b of the cross roller bearing 61. Here, a plate-like mounting stay 83 is integrally provided at a portion corresponding to the flex spline 63 of the second frame 3. As a result, the outer flange portion 69 and the second frame 3 can be fastened together with the outer ring 61 b of the cross roller bearing 61.

  The inner ring 61 a of the cross roller bearing 61 is formed with a tooth portion 84 that meshes with the tooth portion 78 of the flexspline 63 on the inner peripheral surface side. Since the gear main body 68 of the flexspline 63 is deformed into an ellipse by the wave generator 62, the tooth 78 of the gear main body 68 and the tooth 84 of the inner ring 61a, that is, the circular spline, are in the long axis portion of the ellipse of the flexspline 63. 64 is engaged. On the other hand, in the minor axis portion of the ellipse of the flexspline 63, the tooth portions 78 and 84 are completely separated from each other.

Further, the number of teeth of the tooth portion 84 of the inner ring 61 a (circular spline 64) of the cross roller bearing 61 is set to be larger than the number of teeth of the tooth portion 78 formed on the flexspline 63.
Further, a plurality of bolt holes 85 are formed in the inner ring 61a of the cross roller bearing 61, and the bolts 86 are screwed into the inner ring 61a so that the inner ring 61a of the cross roller bearing 61 is moved to the first frame 2 (front frame). Fastened and fixed to the bracket 7).

Next, based on FIG. 3, FIG. 6, operation | movement of the electric rotary joint 1 is demonstrated.
First, when the rotating shaft 5 rotates, for example, clockwise (in the direction of arrow A in FIG. 6), the wave generator 62 of the speed reducer 6 rotates together with the rotating shaft 5.
Then, the gear main body 68 of the flexspline 63 is elastically deformed so as to follow the rotation of the wave generator 62, and the meshing positions of the teeth 78 of the flexspline 63 and the teeth 84 of the circular spline 64 (inner ring 61a) are sequentially changed. Moving.

At this time, the circular spline 64 (the inner ring 61a of the cross roller bearing 61) is fastened and fixed to the first frame 2 (front bracket 7) by the bolt 86, and the number of teeth of the tooth portion 78 of the flexspline 63 is the circular spline. Since it is set to be smaller than the number of teeth of the 64 tooth portions 84, the flexspline 63 rotates counterclockwise (in the direction of arrow C in FIG. 6) by the amount of teeth.
Then, the second frame 3 that is fastened to the outer flange portion 69 of the flexspline 63 with the bolt 76 and the outer ring 61b of the cross roller bearing 61 rotate integrally with the flexspline 63 in the counterclockwise direction. As a result, the second frame 3 rotates about the axis J with respect to the first frame 2.

Next, the flow of air by the axial fan 70 will be described with reference to FIGS.
7 and 8, when the axial fan 70 is driven, the air in the first frame 2 is sucked into the axial fan 70 and discharged toward the electric motor 4 side. At this time, in the first frame 2 and the joint portion 15, the power supply circuit board 52 side has a negative pressure and the electric motor 4 side has a positive pressure with the axial flow fan 70 as the center. For this reason, the wind speed on the electric motor 4 side of the axial fan 70 is faster than the wind speed on the power circuit board 52 side.

  The air discharged from the axial fan 70 hits the peripheral wall 12 of the front bracket 7 of the electric motor 4 and flows out to the outside. At this time, the discharged air flows out along the standing direction of the fins 81. That is, air flows out between the fin 81 and the fin 81.

  The electric motor 4 is efficiently cooled by being blown with air discharged from the axial fan 70. At this time, since the front bracket 7, the fin 81, and the first frame 2 are integrally formed with each other, the heat of the front bracket 7 is transmitted to the fin 81 and the first frame 2. For this reason, the fin 81 and the 1st flame | frame 2 have a role as a heat sink. In particular, since air flows between the fin 81 and the fin 81, heat exchange is efficiently performed between the air and the fin 81.

  On the other hand, the negative pressure side of the axial flow fan 70 has a slower wind speed than the positive pressure side, but the air in the first frame 2 is sucked by the axial flow fan 70, so that while the axial flow fan 70 is driven, Fresh air that does not exchange heat with the power circuit board 52 flows continuously. For this reason, the power supply circuit board 52 can be efficiently cooled as compared with the case where the air in the first frame 2 is stagnant.

Here, the heat generation amount of the power circuit board 52 is smaller than the heat generation amount of the electric motor 4 having a coil to which a current is supplied. For this reason, by disposing the axial fan 70 so that the electric motor 4 side becomes the air discharge side 70b, the electric motor 4 having a large amount of generated heat can be efficiently cooled.
The electric motor 4 is disposed in the joint portion 15 that is open to the atmosphere, whereas the power circuit board 52 is disposed inside the first frame 2 that is surrounded by the power circuit board 52. For this reason, even if the air suction side 70a of the axial flow fan 70 is arranged toward the power circuit board 52, a sufficient wind speed for cooling the power circuit board 52 can be obtained.

Since the motor drive circuit board 51 of the driver device 50 is mounted with the switching element 48 that is repeatedly turned on / off while being supplied with current, the amount of heat generated by the motor drive circuit board 51 is also relatively large.
Since the motor drive circuit board 51 is fixed to the front bracket 7 via the heat radiating sheet 46, the heat of the motor drive circuit board 51 is reduced to the front bracket 7, the fins 81, and the deceleration via the heat radiating sheet 46. Will be transmitted to the machine 6. At this time, since the air discharged from the axial fan 70 is blown to the front bracket 7, the fins 81, and the speed reducer 6, the motor drive circuit board 51 is also efficiently cooled as a result.

Therefore, according to the first embodiment described above, the cooling passage 74 for cooling the electric motor 4 is provided from the first frame 2 to the joint portion 15, and the axial fan 70 is disposed in the middle of the cooling passage 74. By disposing, the driver device 50, the electric motor 4, and the speed reducer 6 can be forcibly cooled by one axial fan 70 while effectively utilizing the empty space inside the first frame 2.
Moreover, the electric motor 4 that generates heat more easily than the power circuit board 52 of the driver device 50 is disposed on the air discharge side 70b of the axial fan 70, while the power circuit board 52 is disposed on the air suction side 70a of the axial fan 70. Since it arrange | positions, while being able to blow a wind with a high wind speed to the electric motor 4 and the reduction gear 6, fresh air can be applied to the power supply circuit board 52 without stagnation.
Therefore, the electric motor 4 and the speed reducer 6 can be efficiently cooled while saving space, and the driver device 50 can be efficiently cooled while the driver device 50 is disposed in the vicinity of the electric motor 4.

Further, by integrally molding the front bracket 7 and the first frame 2 of the electric motor 4, the heat radiation area of the entire electric motor 4 can be increased. For this reason, the electric motor 4 can be cooled more efficiently.
Furthermore, by incorporating the axial fan 70 and the power supply circuit board 52 of the driver device 50 in the first frame 2, it is possible to reduce the size of the electric rotary joint 1 as a whole.

  And since the some fin 81 is standingly arranged along the direction substantially orthogonal to the axis line J between the surrounding wall 12 of the front bracket 7, and the end surface 2a by the side of the electric motor 4 of the 1st frame 2, it is electric. The heat radiation area of the entire motor 4 can be further increased. For this reason, it becomes possible to cool the electric motor 4 and the speed reducer 6 more efficiently.

Further, by dividing the driver device 50 into the motor drive circuit board 51 and the power supply circuit board 52, the layout of the driver device 50 can be improved.
Furthermore, by disposing the motor drive circuit board 51 on the electric motor 4 side, the heat generated by the motor drive circuit board 51 can be dissipated through the first frame 2 and the speed reducer 6, and the power circuit board 52 is pivoted. By disposing on the air suction side 70 a of the flow fan 70, the power supply circuit board 52 can be forcibly cooled using the axial fan 70.
For this reason, it becomes possible to cool efficiently according to the role of each circuit board 51 and 52, and an empty space can be used effectively. Therefore, while further reducing the size of the electric rotary joint 1, it is possible to enhance the cooling effect and improve the motor efficiency.

  By using the axial fan 70 as the forced cooling fan, the thickness direction of the fan itself can be reduced. For this reason, the space occupied in the thickness direction for installing the axial fan 70 can be reduced in size, and the electric rotary joint 1 can be further reduced in size.

  In the first embodiment described above, the case where the axial fan 70 and the power supply circuit board 52 of the driver device 50 are housed in the first frame 2 has been described. However, the present invention is not limited to this, and the axial fan 70 and the power circuit board 52 may be provided in the second frame 3. In this case, the fin 81 functioning as a heat radiating plate is formed integrally with only the front bracket 7 of the electric motor 4 so that the fin 81 and the second frame 3 are separated from each other.

Next, a second embodiment of the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the same aspect as 1st embodiment, and description is abbreviate | omitted (same also about the following embodiment).
In the second embodiment, the electric rotary joint 91 is used, for example, in a joint portion of an industrial robot such as an articulated robot, and the first frame 92 and the second frame 93 are respectively on the same straight line. The configuration in which the motor with a speed reducer is configured by the electric motor 204 and the speed reducer 6 is the first implementation described above. It is the same as the form.
Here, as shown in FIGS. 9 and 10, in the second embodiment, the electric motor 204 and the speed reducer 6 are not provided in the joint portion 15, and the electric motor 204 and the speed reducer are provided in the first frame 92. 6 is provided.

  The first frame 92 has a pair of plates 96a and 96b that face each other in the axis J direction. Each plate 96a, 96b is formed in a rectangular shape in plan view. Ribs 97a and 97b are formed on both sides of the plates 96a and 96b, respectively, so as to rise from the plates 96a and 96b toward the outside in the axis J direction. An annular portion 95 is integrally formed at one end of the plates 96a and 96b on the second frame 93 side (lower side in FIG. 10) in the longitudinal direction. The annular portion 95 constitutes the joint portion 15.

  Further, on both sides of each plate 96a, 96b in the short direction, short side plates 104a, 104b straddling both 96a, 96b are integrally formed from the substantially longitudinal center to the other end (upper end in FIG. 10). Molded. The short side plates 104a and 104b and the plates 96a and 96b form a rectangular tube from the center in the longitudinal direction of the first frame 92 to the other end. Of the two short-side plates 104a and 104b, one short-side plate 104a (the right-side short-side plate 104a in FIG. 10) has a plurality of fins 117 formed so as to extend over the entire longitudinal direction. Are juxtaposed along the short direction.

  Further, of the pair of plates 96a and 96b, one plate 96a (the front side in the drawing in FIG. 10) has a substantially U-shaped opening 98 in the most part from the center in the longitudinal direction to the other end. Is formed. Two motor housings 99a and 99b provided so as to straddle the pair of plates 96a and 96b are integrally formed in the first frame 92 through the opening 98 in a parallel state along the longitudinal direction. .

  The motor housings 99a and 99b are for fixing the electric motor 204 in place of the front bracket 7 and the rear bracket 8 in the first embodiment described above. Each motor housing 99a, 99b is formed in a bottomed cylindrical shape in which the stator core 21 can be fitted and fixed, and the short side plates 104a, 104b come into contact with the outer peripheral surfaces of the motor housings 99a, 99b. Yes. That is, one short side plate 104a and the plurality of fins 117 formed integrally therewith function as a heat sink 118 for radiating heat transmitted to the motor housings 99a and 99b.

  The plates 96a and 96b are integrated with the two motor housings 99a and 99b and the short side plates 104a and 104b. In addition, both sides in the short direction of the plates 96a and 96b protrude from both sides in the short direction of the short side plates 104a and 104b.

  The motor housings 99a and 99b are arranged so that the respective opening portions 101 face opposite sides. That is, of the two motor housings 99a and 99b, one of the motor housings 99a disposed near the annular portion 95 has the opening 101 facing the one plate 96b side (the right side in FIG. 10). Has been placed. The other motor housing 99b is arranged with the opening 101 facing the other plate 96a side (left side in FIG. 10).

Furthermore, an insertion hole 103 through which the rotary shaft 5 of the electric motor 204 can be inserted is formed in the end portion (bottom portion) 102 of each motor housing 99a, 99b.
In the motor housings 99a and 99b, an electric motor 204 is disposed with the encoder 40 facing the opening 101 side. The stator iron core 21 of the electric motor 204 is fitted and fixed to the motor housings 99a and 99b. Each electric motor 204 fixed in such a state is configured such that the speed reducer 6 is attached to one end of the rotary shaft 5 protruding through the insertion hole 103 of the motor housing 99a, 99b.

  That is, of the two electric motors 204, one electric motor 204 arranged closer to the annular portion 95 is arranged such that the speed reducer 6 is provided on the other plate 96a side (left side in FIG. 10). Will be. Further, the other electric motor 204 is arranged so that the speed reducer 6 is provided on one plate 96b side (right side in FIG. 10) (see FIG. 9).

Here, as shown in FIGS. 11 and 12, the tooth portion 111 protruding from the inner peripheral side of the stator core 21 is disposed between the main pole 112 around which the coil 114 is wound and each main pole 112. And the auxiliary electrode 113 around which the coil 114 is not wound.
The main electrode 112 and the auxiliary electrode 113 are each formed in a substantially T shape in an axial plan view. The main pole 112 is detachably provided along the axial direction with respect to the stator core 21, while the auxiliary pole 113 is integrally formed with the stator core 21. That is, a dovetail groove 115 is formed along the axial direction at a location corresponding to the main pole 112 of the stator iron core 21, while a cross section that can be fitted into the dovetail groove 115 is formed at the base end of the main pole 112. A trapezoidal convex portion 116 is integrally formed. Thereby, the main pole 112 is detachably fixed to the stator iron core 21 along the axial direction.

An insulator 127, which is an insulating material, is mounted on the surface of the main pole 112, and the coil 114 is wound from above the insulator 127. The coil 114 is wound only on the main pole 112, but when the current is supplied to the coil 114 due to the presence of the auxiliary pole 113 in the adjacent coil 114, the magnetic flux is supplied to the auxiliary pole 113 together with the main pole 112. A flow of is formed.
Here, the gap between the coil 114 wound around the main electrode 112 and the auxiliary electrode 113 is filled with a resin P having high heat transfer efficiency. Therefore, the resin P is in close contact with the coil 114 and also in close contact with the auxiliary pole 113.

As shown in FIGS. 9, 11, and 13, the motor drive circuit board 121 of the driver device 120 to which each terminal portion of the coil 114 is connected is arranged inside the electric motor 4 as in the first embodiment. Is placed on the heat sink 118 formed on the first frame 92.
The motor drive circuit board 121 is formed in a rectangular shape in plan view, and is provided for each electric motor 4. The two motor drive circuit boards 121 are arranged side by side in the longitudinal direction. The upper portion of the heat sink 118 is covered by these two motor drive circuit boards 121, and a passage T1 surrounded by one short side plate 104a, a plurality of fins 117, and the motor drive circuit board 121 is formed. .

A plurality of switching elements 48 are mounted on the outer surface of the motor drive circuit board 121. The switching element 48 forms an H-bridge circuit for each phase of the coil 114, and the current supplied to the coil 114 is switched for each phase by switching each on / off.
Here, the rising height H1 of the fin 117 is set to be shorter than the height H2 of the plates 96a and 96b protruding from both sides of the short side plate 104a in the short direction. That is, the motor drive circuit board 121 is housed in a housing portion 119 formed by the heat sink 118 and the plates 96a and 96b. And the part which protruded from the short side plate 104a of each plate 96a, 96b has played the role which protects the switching element 48. FIG.

  Also, of the two motor housings 99a and 99b, one motor housing 99a disposed closer to the annular portion 95 is provided with a bracket 123 at the lower end on the annular portion 95 side. A fan 124 is provided. The bracket 123 is formed in a box shape having an opening 123a, and is formed so as to cover the lower part of the heat sink 118 (lower part in FIG. 11) from the lower end of one motor housing 99a. That is, the bracket 123 is attached in a state where the opening 123a faces the one motor housing 99a side. The bracket 123 forms a passage T2 connected to the passage T1 of the heat sink 118 between the bracket 123 and the one motor housing 99a.

  Furthermore, the bottom wall 123b of the bracket 123 is formed with a blower port 125 continuous with the passage T2, and an axial fan 124 is provided so as to close the blower port 125. That is, each of the passages T1 and T2 is configured as a cooling passage 131 through which the air blown from the axial flow fan 124 passes. The axial flow fan 124 is provided at one end of the cooling passage 131, and in the middle of the cooling passage 131, the motor housing 99a. 99b and the motor drive circuit board 121 are arranged.

  The axial fan 124 is disposed with the air suction side 124a facing the annular portion 95 and the air discharge side 124b facing the motor housing 99a. That is, in the first frame 92, the motor housings 99a and 99b and the motor drive circuit board 121 side are in the dynamic pressure and the annular portion 95 side is in the static pressure with the axial fan 124 as the center.

  As shown in FIG. 9, one end of a connecting member (not shown) is rotatably attached to each of the speed reducers 6 and 6 provided in the two electric motors 4 and 4. The other end of one of these two connecting members is rotatably attached to the second frame 93. The other other end of the two connecting members is attached to a third frame (not shown) or the like attached to the opposite side of the second frame 93 to the first frame 92 side. In addition, as a connection member, a connection bar, a timing belt, etc. are mentioned, for example.

The first frame 92 side end portion of the second frame 93 is formed in an arc shape, and discs 94 are provided at both ends in the axis J direction. These discs 94, 94 constitute the joint portion 15 in cooperation with the annular portion 95 of the first frame 92. The second frame 93 is attached to the first frame 92 so as to be rotatable about the axis J by fitting the annular portion 95 to the disc 94.
With this configuration, when the electric motor 4 is driven, the outer ring 61b of the cross roller bearing 61 that constitutes the speed reducer 6 rotates, and the second frame 93 is centered on the axis line J via a connecting member (not shown). Rotate.

Next, based on FIG. 14, FIG. 15, the effect | action of this 2nd embodiment is demonstrated.
As shown in FIGS. 14 and 15, the heat generated in the coil 114 of the electric motor 4 is transmitted to the main pole 112. In addition, since the gap between the coil 114 and the auxiliary electrode 113 is filled with the resin P having high heat transfer efficiency, it is transmitted to the auxiliary electrode 113 via the resin P. The heat transmitted to the main electrode 112 and the auxiliary electrode 113 is transmitted to the motor housings 99a and 99b through the stator core 21.

The heat transmitted to the motor housings 99a and 99b is transmitted to the short side plates 104a and 104b that are in contact with the outer peripheral surfaces of the motor housings 99a and 99b (see arrow X1 in FIG. 15). And since the several fin 117 is integrally molded by the one short side plate 104a of the two short side plates 104a and 104b, heat is transmitted to this several fin 117. FIG.
On the other hand, the heat generated by the switching element 48 mounted on the motor drive circuit board 121 is transmitted to the fin 117 on which it is placed via the motor drive circuit board 121 (see arrow Y1 in FIG. 15).

  Here, the passage T1 formed by the one short side plate 104a, the fin 117, and the motor drive circuit board 121 constitutes a cooling passage 131. That is, the air discharged from the axial fan 124 is efficiently discharged to the cooling passage 131 without leaking to the outside (see arrow Z1 in FIG. 15). Therefore, it is possible to obtain a wind speed sufficient to cool one short side plate 104a, the fin 117, and the motor drive circuit board 121. For this reason, one short side plate 104a, the fin 117, and the motor drive circuit board 121 are efficiently cooled.

  Therefore, according to the second embodiment described above, the driver device 120 (the motor drive circuit board 121) and the electric motor 4 are forcibly cooled by the single axial fan 124 while effectively utilizing the empty space inside the first frame 92. be able to. Further, by integrally molding the motor housings 99a and 99b on the first frame 92, the heat radiation area of the electric motor 4 can be increased. For this reason, the electric motor 4 and the driver device 120 (motor drive circuit board 121) can be efficiently cooled while saving space.

Further, a plurality of fins 117 are provided on one short side plate 104a, and these function as a heat sink 118 for cooling the motor housings 99a and 99b. In addition to this, the motor drive circuit board 121 is placed on the tips of the plurality of fins 117. For this reason, since the heat radiation area of the electric motor 4 and the driver device 120 (motor drive circuit board 121) can be further increased, these can be cooled more efficiently.
Further, wind is sent to a passage T1 surrounded by one short side plate 104a, a plurality of fins 117, and a motor drive circuit board 121, and a passage T2 formed between the bracket 123 and one motor housing 99a. Therefore, the size of the axial fan 124 can be reduced as compared with the first embodiment.

  Since the resin P having high heat transfer efficiency is filled between the coil 114 and the auxiliary electrode 113, the heat generated in the coil 114 is sufficient not only for the main electrode 112 but also for the auxiliary electrode 113 through the resin P. Communicated. For this reason, a sufficient heat transfer path can be secured between the coil 114 and the motor housings 99a and 99b, and the electric motor 4 can be cooled more efficiently.

In the second embodiment described above, the case where a plurality of fins 117 are provided on one short side plate 104a of the two short side plates 104a and 104b has been described. However, the present invention is not limited to this, and the heat sink 118 may be formed by providing a plurality of fins 117 on the other short side plate 104b.
In this case, as shown in FIGS. 16 and 17, one of the two motor drive circuit boards 121 provided for each electric motor 4 is placed on the fin 117 on the other short side plate 104b side. Alternatively, a passage T1 ′ surrounded by the other short side plate 104b, the plurality of fins 117, and the motor drive circuit board 121 may be formed.

16 and 17, when the motor drive circuit board 121 is placed on the fin 117 of each short side plate 104a, 104b, the bracket 133 for attaching the axial fan 124 is It is formed so as to cover the lower part of the motor housing 99a (lower part in FIG. 17) and the lower parts of the two heat sinks 118 and 118.
The bracket 133 is formed in a box shape having an opening 133a, and the opening 133a is arranged toward the one motor housing 99a.

By forming the bracket 133 in this way, a passage T2 is formed on one short side plate 104a side between the bracket 133 and one motor housing 99a, and a passage T2 is formed on the other short side plate 104b side. 'Is formed.
The bottom wall 133b of the bracket 133 is formed with a blower port 134 at the center. The blower port 125 is provided with an axial fan 124 so as to close it.

Under such a configuration, the air discharged from the axial fan 124 branches out at the lower part of the one motor housing 99a and flows out. The air passes through the cooling passage 131 constituted by the passage T1 and the passage T2, and the cooling passage 131 ′ constituted by the passage T1 ′ and the passage T2 ′.
Therefore, even when the plurality of fins 117 are provided on each of the short side plates 104a and 10b, the same effect as when the fins 117 are provided only on one of the short side plates 104a can be obtained.

  In the second embodiment described above, one end of a connecting member (not shown) is rotatably attached to each reduction gear 6 that is a harmonic drive (registered trademark), and the other end of each connecting member is a second one. The case where it is attached to the frame 93 or a third frame (not shown) has been described. However, the present invention is not limited to this, and instead of the speed reducer 6, for example, a speed reduction mechanism using a pulley or the like may be employed.

  Further, in the above-described second embodiment, the case where the gap between the coil 114 wound around the main electrode 112 and the auxiliary electrode 113 is filled with the resin P having high heat transfer efficiency has been described. However, the present invention is not limited to this, and a heat conduction member capable of transferring heat generated in the coil 114 to the auxiliary electrode 113 may be interposed in the gap between the coil 114 and the auxiliary electrode 113. For example, a heat radiating sheet or the like may be used in place of the resin P.

Furthermore, the present invention is not limited to the above-described embodiment, and includes various modifications made to the above-described embodiment without departing from the spirit of the present invention.
For example, in the above-described first embodiment, the case where the axial flow fan 70 is used as the forced cooling fan has been described, and in the above-described second embodiment, the case where the axial flow fan 124 is used has been described. However, the present invention is not limited to this, and a fan other than the axial fans 70 and 124, such as a sirocco fan, may be used.

1,91 Electric rotary joint 2 First frame (one frame)
3 Second frame (the other frame)
4,204 Electric motor (motor with reduction gear)
5 Rotating shaft 6 Reducer (Deceleration mechanism)
7 Front bracket (casing)
DESCRIPTION OF SYMBOLS 10 Stator 11 Rotor 15 Joint part 48 Switching element 50, 120 Driver device 51, 121 Motor drive circuit board 52 Power supply circuit board 52a, 52b Board 58 Aluminum electrolytic capacitor (smoothing capacitor)
70 Axial fan (fan)
70a, 124a Air suction side 70b, 124b Air discharge side 74, 131 Cooling passage 81 Fin 91 First frame (one frame)
92 Second frame (other frames)
96a, 96b Plate 99a, 99b Motor housing (casing)
104a, 104b Short side plate (base part)
111 Teeth section 112 Main pole 113 Supplementary pole 114 Coil 117 Fin 118 Heat sink P Resin (thermal conduction member)
T1, T1 ', T2, T2' passage (cooling passage)

Claims (8)

An electric rotary joint in which a motor with a speed reducer is provided at a joint portion that connects one frame and the other frame, and the one frame and the other frame are rotatably connected via the motor with a speed reducer. ,
The motor with a speed reducer is
It has a driver device for performing rotation control of this rotating shaft,
At least a part of the driver device is built in either the one frame or the other frame,
A cooling passage for cooling the motor with a speed reducer is provided in the joint portion, and the one frame or the other frame, and a blower fan is provided in the middle of the cooling passage,
An electric rotary joint, wherein at least a part of the driver device is disposed on an air suction side of the blower fan, and the motor with a speed reducer is disposed on an air discharge side of the blower fan. The one frame and the casing of the motor with a reduction gear are integrally formed,
Linking the other frame and the speed reducer with the speed reducer,
The electric rotary joint according to claim 1, wherein at least a part of the blower fan and the driver device is built in the one frame. A plurality of fins are provided along the air flow in the cooling passage,
The electric rotary joint according to claim 1, wherein the plurality of fins are integrally formed with at least a casing of the motor with a reduction gear. The driver device is:
A motor drive circuit board on which switching elements constituting a bridge circuit are mounted, and a power supply circuit board that supplies a current to the motor drive circuit board and has a smoothing capacitor, are divided,
The motor drive circuit board is disposed on the motor side with the speed reducer,
The electric rotary joint according to any one of claims 1 to 3, wherein the power circuit board is disposed on an air suction side of the blower fan.   The electric rotary joint according to any one of claims 1 to 4, wherein the blower fan is an axial fan. At least two frames are rotatably connected via a joint portion, and a motor with a speed reducer is provided on one of the frames,
The motor with a speed reducer is
An annular stator;
A rotor provided rotatably on the radially inner side of the stator;
A reduction mechanism that is provided on one end of the rotor and that outputs the rotation speed of the rotating shaft of the rotor by decelerating;
A driver device for performing rotation control of the rotating shaft,
An electric rotary joint that connects the deceleration mechanism and another frame of the frames to rotate the other frame around the joint portion,
A cooling passage for cooling the motor with a reduction gear is provided in the one frame, and a casing for fixing the stator is integrally formed in the middle of the cooling passage, and at least a part of the driver device is disposed. And
A blower fan is provided on one end side of the cooling passage, and the blower fan is disposed with the air discharge side facing the cooling passage. The stator is
A cylindrical stator iron core fitted and fixed to the casing;
A plurality of teeth portions projecting radially inward from the stator core;
The teeth part is
A main pole arranged at equal intervals in the circumferential direction and wound with a coil;
It is composed of an auxiliary pole arranged between the main poles and not wound with the coil,
The electric rotary joint according to claim 6, wherein a heat conduction member in contact with the coil and the auxiliary electrode is interposed in a gap between the coil and the auxiliary electrode. A heat sink is provided in the casing,
The heat sink is
A base portion in contact with the casing;
A plurality of fins formed so as to rise from the base portion, each arranged in parallel;
Disposing at least a part of the driver device on the tip side of the plurality of fins;
The electric rotary joint according to claim 6 or 7, wherein a passage formed by at least a part of the base portion, the plurality of fins, and the driver device is configured as the cooling passage.

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