CN211456940U

CN211456940U - Servo motor

Info

Publication number: CN211456940U
Application number: CN201922231438.1U
Authority: CN
Inventors: 小菅启之; 吉野明; 斋藤清康
Original assignee: Nidec Copal Corp
Current assignee: Nidec Precision Corp
Priority date: 2018-12-27
Filing date: 2019-12-12
Publication date: 2020-09-08
Anticipated expiration: 2029-12-12
Also published as: JP2020108240A; JP7284578B2

Abstract

Provided is a servo motor, which can detect the coil temperature of the servo motor with high precision and control based on the accurate coil temperature. A servo motor (1) is provided with: a motor case (2) having a bottomed cylindrical motor case (10) and an end cover (20); a stator coil (30) disposed on the inner peripheral side of the motor housing; a rotor (1A) having a magnet (40) disposed on the inner peripheral side of the stator coil and an output shaft (3A); a control substrate (4) having a first substrate portion (41) disposed inside the motor case and a second substrate portion (42) disposed outside the motor case; a thermistor (8) disposed on the first substrate portion (41); and an electronic component (5) for rotation control, which is disposed on the second substrate portion (42). The first substrate part (41) has an opposing region (R) that opposes the stator coil (30) in the Z direction, and at least a part of the thermistor (8) is disposed in the opposing region (R).

Description

Servo motor

Technical Field

The utility model relates to a servo motor.

Background

Conventionally, a servo motor is used which controls rotation based on detected values such as position and speed. For example, in a gear motor having a servo motor and a gear unit, the position, speed, and the like of an output gear or a driven member are controlled by detecting the rotational position of the output gear or the position of the driven member and controlling the drive current of the servo motor. Patent document 1 discloses a gear motor having such a servomotor.

Patent document 1: japanese patent application laid-open No. 2018-64405

In a servo motor, in order to prevent a trouble such as winding burnout from occurring due to the influence of heat generation of a coil caused by energization, a coil temperature is monitored, and when the coil temperature exceeds a predetermined upper limit temperature, a limit control is performed to stop the motor.

In the case where the servo motor is a brush motor, since the coil as a heat generation source is provided in the rotor, it is difficult to bring the coil close to the thermistor. Therefore, conventionally, the thermistor is disposed outside the motor case. Therefore, the coil temperature cannot be detected with high accuracy, and control cannot be performed based on an accurate coil temperature.

SUMMERY OF THE UTILITY MODEL

In view of the above problem, an object of the present invention is to detect the coil temperature of a servo motor with high accuracy, and to perform control based on the accurate coil temperature.

The servo motor of the present invention is characterized in that it has: a motor case having a bottomed cylindrical motor case extending in an axial direction and an end cap fixed to an opening of the motor case; a stator coil disposed on an inner peripheral side of the motor case; a rotor having a magnet disposed on an inner peripheral side of the stator coil; a control substrate having a first substrate portion disposed inside the motor case and a second substrate portion disposed outside the motor case; a thermistor disposed on the first substrate portion; and an electronic component for rotation control disposed on the second substrate portion, wherein the first substrate portion has an opposing region opposing the stator coil in the axial direction, and at least a part of the thermistor is disposed in the opposing region.

According to the illustrated embodiment of the present invention, the coil temperature of the servo motor can be measured with high accuracy, and therefore, control based on the accurate coil temperature can be performed.

Drawings

Fig. 1 is a side view of a servo motor according to an embodiment of the present invention.

Fig. 2 is a sectional view of the servo motor of fig. 1 and a partially enlarged view thereof.

Fig. 3 is an exploded perspective view of the servo motor of fig. 1.

Fig. 4 is a configuration diagram of a thermistor and a hall IC.

Fig. 5 is a layout diagram of a thermistor and a hall IC of a modification.

Description of the reference symbols

1: a servo motor; 1A: a rotor; 2: a motor housing; 3: a rotating shaft; 3A: an output shaft; 4: a control substrate; 5: an electronic component for rotation control; 6: a connector; 7: a Hall IC; 8: a thermistor; 9: an elastic member; 10: a motor housing; 11: an opening part; 12: a barrel portion; 13: an end plate portion; 14: a circular hole; 15: a cut-out portion; 16: a protrusion; 19: a gasket; 20: an end cap; 21: a circular hole; 22: an inner cylindrical portion; 23: an inner annular portion; 24: an outer cylindrical portion; 25: an outer annular portion; 30: a stator coil; 31: a winding; 40: a magnet; 41: a first substrate portion; 42: a second substrate portion; 43: a central bore; 44: a cut-out portion; 45: a protrusion; 46: an annular portion; 50: a back yoke; 61: a first bearing member; 62: a second bearing component; 71: a thrust bushing; 72: a gasket; 73: an adhesive; 80: a heat conductive member; h1: the height of the washer in the axial direction; h2: height of the hall IC in the axial direction; l: a rotation axis; r: an opposing region; s: a gap between the stator coil and the first substrate portion.

Detailed Description

Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. In this specification, 3 directions perpendicular to each other are referred to as an X direction, a Y direction, and a Z direction. The Z direction is the axis direction of the servomotor. Further, one side in the Z direction is Z1, the other side in the Z direction is Z2, one side in the X direction is X1, the other side in the X direction is X2, one side in the Y direction is Y1, and the other side in the Y direction is Y2.

< Structure of servomotor >

Fig. 1 is a side view of a servo motor 1 according to an embodiment of the present invention. The servomotor 1 is used for driving various driven members. As shown in fig. 1, the servomotor 1 includes: a motor housing 2; a rotary shaft 3 having an output shaft 3A protruding from the motor case 2 to the Z1 side; and a control board 4, a part of which is housed in the motor case 2. For example, when the rotation of the servomotor 1 is decelerated by a gear unit not shown and transmitted to the driven member, an input gear of the gear unit is fixed to the output shaft 3A. The rotary shaft 3 is disposed at the center of the motor housing 2 and extends in the Z direction. The rotary shaft 3 rotates about a rotation axis L extending in the Z direction.

The control substrate 4 has a first substrate portion 41 disposed inside the motor case 2 and a second substrate portion 42 disposed outside the motor case 2. The portion on the X1 side of the control substrate 4 is the second substrate portion 42, and the portion on the X2 side is the first substrate portion 41. The second base plate portion 42 protrudes from the motor housing 2 in the X1 direction.

A wiring pattern, not shown, is formed on the control substrate 4, and electronic components are arranged. The electronic components disposed on the second substrate portion 42 include the electronic components 5 for rotation control, and the electronic components 5 constitute a control circuit for controlling the rotation of the servomotor 1. The electronic component 5 for rotation control is, for example, a microcontroller, a gate driver, an FET, or the like. The control circuit of the servomotor 1 detects the rotational position of the driven member driven in accordance with the rotation of the output shaft 3A by, for example, a sensor not shown, and controls the drive current of the servomotor 1 in accordance with the rotational position of the driven member.

A connector 6 for connecting the circuit on the control substrate 4 to an external device is disposed on the second substrate portion 42. In the present embodiment, the electronic component 5 is disposed on the surface of the second substrate portion 42 on the Z1 side, and the connector 6 is disposed on the surface on the Z2 side. The electronic component 5 and the connector 6 may be disposed on any surface of the second substrate portion 42.

The servomotor 1 includes, as electronic components disposed on the control board 4, at least a hall IC7 and a thermistor 8 (see fig. 2 and 3) described later, in addition to the rotation control electronic component 5 and the connector 6. The hall IC7 and the thermistor 8 are disposed on the first substrate portion 41 and are housed inside the motor case 2.

Fig. 2 is a sectional view of the servo motor 1 of fig. 1 and a partially enlarged view thereof. Fig. 3 is an exploded perspective view of the servo motor 1 of fig. 1. Hereinafter, the motor housing 2 and the internal structure thereof will be described with reference to fig. 2 and 3. The motor housing 2 has a motor case 10 and an end cover 20. The motor case 10 has a bottomed cylindrical shape and extends in the Z direction (axial direction). The end cap 20 is fixed to an opening 11, and the opening 11 is provided at an end of the motor case 10 in the Z2 direction. The motor housing 10 is made of metal, and the end cap 20 is made of resin. In addition, the end cap 20 may also be made of metal.

The motor housing 10 includes a cylindrical tube portion 12 and an end plate portion 13 that closes an end portion of the tube portion 12 in the Z1 direction. The rotary shaft 3 is rotatably supported by a first bearing member 61 attached to the motor housing 10 and a second bearing member 62 attached to the end cover 20. The first bearing member 61 is disposed in the circular hole 14, and the circular hole 14 penetrates through the center portion of the end plate portion 13 of the motor case 10. The second bearing member 62 is disposed in the circular hole 21, and the circular hole 21 penetrates through the center portion of the end cap 20.

A stator coil 30, a magnet 40 disposed on the inner peripheral side of the stator coil 30, and a back yoke 50 supporting the stator coil 30 are disposed on the inner peripheral side of the motor case 10. The back yoke 50 is fixed to the inner circumferential surface of the tube portion 12 of the motor case 10. The stator coil 30 is fixed to the inner peripheral surface of the back yoke 50. Therefore, the stator coil 30 is fixed to the motor case 10 via the back yoke 50. The back yoke 50 is fixed to the motor housing 10 by pressing and an adhesive. The stator coil 30 is fixed to the back yoke 50 by an adhesive.

The stator coil 30 and the back yoke 50 are fixed to the motor case 2, and constitute a stator portion of the servo motor 1. The servomotor 1 has a rotor 1A that rotates relative to the stator portion. The rotor 1A includes a rotary shaft 3 and a magnet 40 fixed to the rotary shaft 3. The rotor 1A is disposed at a position where the magnet 40 and the stator coil 30 radially face each other. The rotor 1A is supported to be rotatable about a rotation shaft 3.

The stator coil 30 is a cylindrical coil having U-phase, V-phase, and W-phase windings 31. The back yoke 50 is made of metal, and is a laminated plate obtained by laminating annular metal plates. As shown in fig. 2, the length (height) of the back yoke 50 in the Z direction is smaller than the length (height) of the stator coil 30 in the Z direction. The back yoke 50 is fixed to the motor case 10 at a position closer to the Z1 side than the center in the Z direction. The end of the stator coil 30 on the Z1 side protrudes from the back yoke 50 toward the Z1 side and extends to the vicinity of the end plate portion 13 of the motor case 10. A gasket 19 is interposed between the stator coil 30 and the end plate portion 13. The end of the stator coil 30 on the Z2 side protrudes from the back yoke 50 toward the Z2 side. The end of the stator coil 30 on the Z2 side faces the first substrate portion 41 disposed in the opening 11 of the motor case 10. A Z-direction gap S is formed between the stator coil 30 and the first substrate portion 41. The stator coil 30 is connected to the first substrate portion 41 by drawing out the end portions of the respective 2U-phase, V-phase, and W-phase windings 31 in the Z2 direction.

< fixing Structure of control Board >

As shown in fig. 2, the first substrate portion 41 is disposed on the Z2 side of the stator coil 30 and the magnet 40. As shown in fig. 3, a circular center hole 43 is provided in the center of the first substrate portion 41. As shown in fig. 2, the rotary shaft 3 passes through the center hole 43, and is held by the second bearing member 62 on the Z2 side of the center hole 43. The first base plate portion 41 is fixed to the motor case 2 by being sandwiched between the end portion of the motor case 10 in the Z2 direction and the end cover 20 in the Z direction (axial direction). Further, an elastic member 9 is disposed between the first substrate portion 41 and the end cap 20.

As shown in fig. 3, notches 44 cut radially inward are provided at a plurality of positions on the outer peripheral edge of the first substrate portion 41. Each of the cutout portions 44 is cut inward in the radial direction with a size that both end portions in the circumferential direction are slightly larger than the plate thickness (thickness in the radial direction) of the motor case 10. Further, the central portion in the circumferential direction of each notch 44 is notched radially inward more than both end portions in the circumferential direction. In the present embodiment, the cutout portions 44 are provided at 3 at intervals of 120 °. At the 3-position notch 44, the U-phase, V-phase, and W-phase windings 31 are disposed, which are drawn out from the stator coil 30 in the Z2 direction.

The first substrate portion 41 has: a protruding portion 45 provided between the circumferentially adjacent cutout portions 44; and an annular portion 46 provided on the inner peripheral side of the protruding portion 45. The radially outer end edge of the projection 45 is formed in an arc shape centering on the center point of the center hole 43. In the present embodiment, the protruding portions 45 are arranged at 3 at intervals of 120 ° as in the case of the notch portions 44. 1 of the 3-position protrusions 45 faces in the direction X1 and is connected to the second substrate portion 42. The number of the notches 44 and the protrusions 45 may be other than 3.

The control substrate 4 is fixed to the motor case 2 by sandwiching the front end portion of the protruding portion 45 of the first substrate portion 41 between the motor case 10 and the end cover 20. As shown in fig. 3, the motor housing 10 has notch portions 15 formed by cutting the end portion of the tubular portion 12 on the opening 11 side (Z2 side) in the Z1 direction at a plurality of positions. Each cutout portion 15 is provided at a position overlapping the protruding portion 45 of the first substrate portion 41 when viewed from the Z direction. As described above, the protruding portion 45 is provided at 3, and therefore the cutout portion 15 is also provided at 3.

At the end of the motor case 10 on the opening 11 side (Z2 side), a protruding portion 16 protruding in the Z2 direction is provided between circumferentially adjacent cut-out portions 15. When the control board 4 and the motor case 2 are assembled, the first board portion 41 is fitted into the opening 11 of the motor case 10 from the Z2 side. At this time, the protruding portions 45 of the first substrate portion 41 are arranged at the 3-place cutout portions 15, respectively. Next, the end cap 20 is fitted into the inner peripheral side of the protruding portion 16 from the Z2 side of the first substrate portion 41. At this time, the annular elastic member 9 is disposed between the first substrate portion 41 and the end cap 20. By attaching the double-sided tape to the surface of the elastic member 9 and attaching the elastic member 9 to the end cap 20 for assembly, the positional displacement of the elastic member 9 can be suppressed, and the assemblability can be improved. Then, the end cap 20 is fixed to the motor case 10 by pressing the 3-projection 16 from the outer peripheral side.

When the end cover 20 is fixed, the first base plate portion 41 sandwiches the 3-position projecting portion 45 between the edge of the cutout portion 15 of the motor case 10 and the end cover 20. The elastic member 9 overlaps with the front end portion of the protruding portion 45 when viewed from the Z direction. Therefore, the elastic member 9 is interposed between the end cap 20 and the protrusion 45. The elastic member 9 is compressed in the Z direction between the end cap 20 and the protrusion 45 and elastically deformed. Therefore, the first base plate portion 41 is pressed against the motor housing 2 by the elastic restoring force of the elastic member 9.

As shown in fig. 2 and 3, the end cap 20 has: an inner cylindrical portion 22 surrounding the circular hole 21; an inner annular portion 23 that extends while being bent radially outward from an end portion of the inner cylindrical portion 22 in the Z2 direction; an outer cylindrical portion 24 that extends from an outer circumferential end of the inner annular portion 23 while being bent in the Z1 direction; and an outer annular portion 25 that extends while being bent radially outward from an end portion of the outer cylindrical portion 24 in the Z1 direction. In the end cap 20, the portion holding the second bearing member 62 is the cylindrical inner cylindrical portion 22, and therefore the second bearing member 62 can be stably held.

< arrangement of thermistor and Hall IC >

Fig. 4 is a layout diagram of the thermistor and the hall IC, and is a plan view of the control board 4 viewed from the Z1 side. In fig. 4, the broken line indicates the shape of the stator coil 30 as viewed from the Z1 side. As shown in fig. 2 and 4, the first substrate portion 41 has an annular facing region R that faces the stator coil 30 in the Z direction (axial direction). The central portion in the circumferential direction of the cutout portion 44 of the first substrate portion 41 is located in the opposing region R. As described above, the U-phase, V-phase, and W-phase windings 31 drawn from the stator coil 30 are arranged at the circumferential center of the 3-point cutout 44.

The hall IC7 is disposed on the surface of the first substrate portion 41 on the Z1 side. The surface of the first substrate portion 41 on the Z1 side is a surface facing the magnet 40. The hall IC7 is connected to a control circuit provided in the second substrate portion 42 via a wiring pattern. The control circuit detects the rotational position of the rotor 1A from the output of the hall IC 7. In the present embodiment, the hall ICs 7 are arranged at 3 at intervals of 120 °. Each hall IC7 is disposed at an angular position that coincides with the center in the circumferential direction of the protruding portion 45 in the annular portion 46 of the first substrate portion 41. As shown in fig. 2, a part of each hall IC7 faces the magnet 40 in the Z direction.

The thermistor 8 is disposed on the surface of the first substrate portion 41 on the Z1 side. That is, the thermistor 8 is disposed on a surface of the first substrate portion 41 on the side facing the stator coil 30. The thermistor 8 is connected to a control circuit provided in the second substrate portion 42 via a wiring pattern. The control circuit detects the coil temperature based on the output of the thermistor 8. The control circuit controls the current supplied to the stator coil 30 in accordance with the coil temperature. For example, limit control for preventing burning of the winding 31 is performed.

At least a part of the thermistor 8 is disposed in the facing region R. As shown in fig. 2 and 4, the thermistor 8 is disposed on the outer periphery side of the hall IC7, and the end of the thermistor 8 on the hall IC7 side (X2 side) is disposed in the facing region R. In the first substrate portion 41, the opposing region R is a position closest to the stator coil 30. Therefore, by disposing the thermistor 8 in the facing region R, the thermistor 8 and the stator coil 30 can be brought closest to each other.

The thermistor 8 is disposed on the same side (X1 side) as the second substrate portion 42 with respect to the rotation axis L as the center of the stator coil 30 when viewed from the Z direction (axial direction). That is, in the first substrate portion 41, the thermistor 8 is disposed in a region where the distance from the second substrate portion 42 is small and the wiring length for connection to the control circuit provided in the second substrate portion 42 is short. More specifically, the thermistor 8 is disposed at the center in the circumferential direction of the protruding portion 45 connected to the second substrate portion 42. The center in the circumferential direction of the protruding portion 45 connected to the second substrate portion 42 is a position where the distance from the control circuit provided in the second substrate portion 42 is minimum.

< Heat-conductive Member >

As shown in fig. 2, a heat conductive member 80 having a higher thermal conductivity than air is disposed in a gap between the stator coil 30 and the thermistor 8. The heat conduction member 80 is disposed in a state where the Z1 side is in contact with the stator coil 30 and the Z2 side is in contact with the thermistor 8. Thereby, the heat of the stator coil 30 is easily transmitted to the thermistor 8, and the heat of the stator coil 30 is not easily escaped to the first substrate portion 41. For example, a heat conductive adhesive having higher heat conductivity than air can be used as the heat conductive member 80. Alternatively, a heat conductive tape can be used as the heat conductive member 80.

< spacer >

Spacers for regulating the Z-direction movement of the rotor 1A are attached to the rotary shaft 3 on the Z1 side and the Z2 side of the magnet 40, respectively. In the present embodiment, the spacer includes a thrust bushing 71 and a washer 72, the thrust bushing 71 is disposed between the first bearing member 61 and the magnet 40, and the washer 72 is disposed between the magnet 40 and the first base plate portion 41. As shown in fig. 2, the thrust washer 71 is in surface contact with the magnet 40 in the Z1 direction. On the other hand, the washer 72 is fixed to a surface of the magnet 40 facing away from the Z2 direction. An adhesive 73 is disposed in a gap between the washer 72 and the surface of the magnet 40 in the Z2 direction.

As shown in fig. 2, the outer peripheral portion of the gasket 72 is opposed to the edge of the central hole 43 of the first base plate portion 41 in the Z direction. Therefore, the movement of the rotor 1A to the Z2 side is restricted by the washer 72 colliding with the first base plate portion 41. As shown in fig. 2, the height H1 in the Z direction (axial direction) of the washer 72 functioning as a spacer is larger than the height H2 in the Z direction (axial direction) of the hall IC 7. By disposing the washer 72 having such a size on the first base plate portion 41 side (Z2 side) of the magnet 40, the moving range of the rotor 1A can be limited to a range in which the distance between the magnet 40 and the first base plate portion 41 is not less than the height H1 of the washer 72. Therefore, the magnet 40 can be prevented from colliding with the hall IC 7.

< main effects of the present embodiment >

As described above, the servomotor 1 of the present embodiment includes: a motor case 2 having a bottomed cylindrical motor case 10 and an end cap 20, the motor case 10 extending in the Z direction (axial direction), the end cap 20 being fixed to an opening 11 of the motor case 10; a stator coil 30 disposed on the inner peripheral side of the motor case 10; a rotor 1A having a magnet 40 disposed on an inner peripheral side of the stator coil 30 and a rotating shaft 3; a control substrate 4 having a first substrate portion 41 disposed inside the motor case 2 and a second substrate portion 42 disposed outside the motor case 2; a thermistor 8 disposed on the first substrate portion 41; and an electronic component 5 for rotation control disposed on the second substrate portion 42. The first substrate portion 41 has an opposing region R that opposes the stator coil 30 in the Z direction (axial direction), and at least a part of the thermistor 8 is disposed in the opposing region R.

In the present embodiment, the first substrate portion 41 of the control substrate 4 is disposed inside the motor case 2, and the thermistor 8 is disposed on the first substrate portion 41. Thus, the thermistor 8 can be disposed inside the motor case 2, and therefore, the thermistor can be disposed in the vicinity of the stator coil 30. At least a part of the thermistor 8 is disposed in an opposing region R of the first substrate portion 41 that opposes the stator coil 30 in the Z direction (axial direction). By disposing the thermistor 8 at a position on the control board 4 that faces the stator coil 30 in the Z direction (axial direction) in this way, the coil temperature can be measured in the vicinity of the stator coil 30. Therefore, the coil temperature can be measured with high accuracy, and control based on the accurate coil temperature can be performed. For example, the limit control for preventing the burning of the winding 31 can be performed in accordance with the accurate coil temperature.

In the present embodiment, the thermistor 8 and the hall IC7 are disposed with a part of the control board 4 housed inside the motor case 2, and the electronic component 5 for rotation control and the connector 6 are disposed with the other part of the control board 4 disposed outside the motor case 2. In this way, the thermistor 8, the hall IC7, the electronic component 5, and the connector 6 are mounted on a common substrate and integrally assembled with the motor case 2, whereby the wiring structure of the entire servomotor 1 can be simplified. In particular, although the servo motor 1 has a structure in which the thermistor 8 is disposed inside the motor case 2 and the control circuit is disposed outside the motor case 2, wiring to the thermistor 8 and the hall IC7 can be performed inside the substrate. In addition, the first substrate portion 41 can be used to perform wiring to the stator coil 30. Therefore, the wiring structure can be simplified.

In the present embodiment, a heat conductive member 80 having a higher thermal conductivity than air is disposed between the thermistor 8 and the stator coil 30. Therefore, since the heat of the stator coil 30 is transmitted to the thermistor 8 via the heat conductive member 80, the heat of the stator coil 30 is less likely to escape to the first substrate portion 41 than in a structure in which the heat of the stator coil 30 is transmitted to the thermistor 8 via air. Therefore, the coil temperature can be measured more accurately, and therefore, control based on more accurate temperature can be performed.

In the present embodiment, the first base plate portion 41 is sandwiched and fixed between the motor case 10 and the end cover 20 in the Z direction (axial direction). Therefore, the servomotor 1 and the control board 4 can be integrally assembled without an additional fixing member. Therefore, the number of parts can be reduced.

In the present embodiment, the elastic member 9 is disposed between the end cap 20 and the first substrate portion 41. Therefore, the first substrate portion 41 can be pressed against the motor case 10 by the elastic member 9, and therefore, vibration of the control substrate 4 can be suppressed when the servo motor 1 is driven. Therefore, chatter sound caused by vibration of the control board 4 can be suppressed, and silencing can be achieved.

In the present embodiment, the washer 72 functioning as a spacer is disposed between the magnet 40 and the first substrate portion 41, and the height H1 in the Z direction (axial direction) of the washer 72 is larger than the height H2 in the Z direction (axial direction) of the hall IC 7. Therefore, the washer 72 can suppress the movement of the rotor 1A in the thrust direction, and the hall IC7 can be prevented from colliding with the magnet 40, thereby suppressing damage to the hall IC 7.

In the present embodiment, the thermistor 8 is located on the same side (X1 side) as the second substrate portion 42 with respect to the center of the stator coil 30 when viewed from the Z direction (axial direction). With this arrangement, the distance between the thermistor 8 and the electronic component 5 for rotation control mounted on the second substrate portion 42 can be reduced, and therefore the wiring length can be shortened, and the wiring pattern on the control substrate 4 can be simplified.

< modification example >

Fig. 5 is a layout diagram of the thermistor 8 and the hall IC7 of a modification. In the above-described embodiment, only a part of the thermistor 8 is disposed in the facing region R, but in the arrangement shown in fig. 5, the entire thermistor 8 is disposed in the facing region R. In the arrangement shown in fig. 5, the hall IC7 is arranged on the inner peripheral side of the stator coil 30 as viewed in the Z direction (axial direction). By offsetting the position of the hall IC7 from the stator coil 30 toward the inner peripheral side in this way, the entire space in which the thermistor 8 is disposed in the opposing region R can be secured.

When the entire thermistor 8 is disposed in the facing region R, the heat of the stator coil 30 most easily reaches the thermistor 8. Therefore, the coil temperature can be measured with higher accuracy. Therefore, more accurate control based on the coil temperature can be performed. For example, the limit control for preventing the burning of the winding 31 can be performed in accordance with the more accurate coil temperature. In the arrangement of fig. 5, as in the above-described embodiment, it is preferable to dispose a heat conductive member 80 having a higher thermal conductivity than air between the thermistor 8 and the stator coil 30. This makes it less likely that the heat of the stator coil 30 escapes to the first substrate portion 41, and therefore the coil temperature can be measured more accurately. Therefore, the control based on the coil temperature can be performed according to the accurate coil temperature.

Claims

1. A servo motor is characterized in that a servo motor is provided,

the servo motor includes:

a motor case having a bottomed cylindrical motor case extending in an axial direction and an end cap fixed to an opening of the motor case;

a stator coil disposed on an inner peripheral side of the motor case;

a rotor having a magnet disposed on an inner peripheral side of the stator coil;

a control substrate having a first substrate portion disposed inside the motor case and a second substrate portion disposed outside the motor case;

a thermistor disposed on the first substrate portion; and

an electronic component for rotation control disposed on the second substrate portion,

the first substrate portion has an opposing region that opposes the stator coil in the axial direction,

at least a part of the thermistor is disposed in the opposing region.

2. Servo motor according to claim 1,

the entirety of the thermistor is disposed in the opposing region.

3. Servo motor according to claim 1,

a heat conductive member having a higher thermal conductivity than air is disposed between the thermistor and the stator coil.

4. Servo motor according to claim 2,

5. Servo motor according to any of claims 1 to 4,

the first base plate portion is fixed by being sandwiched between the motor case and the end cover in the axis direction.

6. Servo motor according to claim 5,

an elastic member is disposed between the end cap and the first substrate portion.

7. Servo motor according to any of claims 1 to 4,

the servo motor has a Hall IC disposed on the first substrate portion,

the hall IC is disposed on an inner peripheral side of the stator coil when viewed in the axial direction.

8. Servo motor according to claim 7,

the servo motor has a spacer disposed between the magnet and the first substrate portion,

the height of the spacer in the axis line direction is larger than the height of the hall IC in the axis line direction.

9. Servo motor according to any of claims 1 to 4,

the thermistor is located on the same side as the second substrate portion with respect to the center of the stator coil when viewed from the axial direction.