JP2013099198A - Rotary actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary actuator that has enhanced heat dissipation properties and can suppress pulsation of an output torque.SOLUTION: A rotary actuator 15 includes: an SR motor 40; a resin housing 20 to accommodate the SR motor 40; and a heat sink 80. The heat sink 80 has three protrusions 82, 83 and 84 that protrude radially from a core part 81 constituting a stator core 42 to the outside of the housing 20. The protrusions 82, 83 and 84 are respectively disposed in coils 45, 46 and 47. The heat of the stator core 42 can be conducted directly to the individual protrusions. The stator core 42 and the heat sink 80 form a heat conduction path that conducts and releases the heat of the individual coils to the outside of the housing 20. This achieves enhanced heat dissipation properties. It is also capable of suppressing pulsation of an output torque of the SR motor 40 by allowing each of phase coils to have an equal amount of heat released.

Description

  The present invention relates to a rotary actuator.

  Conventionally, for example, a rotary actuator used in a drive unit of a shift-by-wire system is known. For example, the rotary actuator disclosed in Patent Document 1 includes a motor including a rotor and a stator. The stator includes a U-phase coil, a V-phase coil, and a W-phase coil, and generates a magnetic field that rotates around the rotor by sequentially energizing each phase coil. The motor is covered with a resin housing.

JP 2009-177982 A

  In the rotary actuator disclosed in Patent Document 1, since the motor is covered with a resin having a lower thermal conductivity than metal, it is difficult to release heat generated in the stator coil and the like out of the housing, that is, heat dissipation is low. There was a problem. When the temperature in the housing rises due to this low heat dissipation, the number of continuous operation of the motor has to be limited, and the electric resistance of the coil increases and the output torque of the motor may decrease.

Further, in the rotary actuator disclosed in Patent Document 1, since the heat radiation amount differs for each phase coil, there is a problem that the strength of the magnetic field generated by each phase coil differs and the pulsation of the output torque of the motor increases. there were.
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a rotary actuator that has high heat dissipation and can suppress pulsation of output torque of a motor.

A rotary actuator according to a first aspect of the present invention includes a motor composed of a rotor and a stator, a housing that accommodates the motor, and a plurality of heat radiation means.
The rotor is rotatably supported by the housing. The stator includes a stator core and a plurality of phase coils, and is fixedly supported by the housing. The stator core includes a ring portion provided in a radially outward direction of the rotor, and a plurality of teeth portions protruding from the ring portion toward the rotor and spaced apart from each other in the circumferential direction. Each coil is composed of a conductive wire wound around each tooth portion of the stator core.

  Each of the heat dissipating means protrudes radially outward from the housing in the same number for each phase of the coil from the position of the stator core in the radial direction with respect to the coil. The heat of the stator core can be directly conducted to each heat radiating means. Each heat radiating means radiates the conducted heat.

  According to such a rotary actuator, the stator core and the heat radiating means form a heat conduction path for conducting the heat of the coil to the outside of the housing and radiating the heat. Most of the heat generated in each coil is dissipated outside the housing via the heat conduction path without going through the resin housing. Thereby, high heat dissipation can be obtained, and an increase in temperature in the housing can be suppressed. Therefore, the restriction on the number of continuous operation of the motor can be relaxed, and the decrease in the output torque of the motor due to the increase in the electric resistance of the coil can be suppressed.

  Further, the same number of heat dissipating means is provided for each phase coil. Thereby, the amount of heat radiation can be made uniform for each phase coil. Therefore, the strength of the magnetic field generated by each phase coil can be made uniform in the rotational direction, and the pulsation of the output torque of the motor can be suppressed.

In the invention according to claim 2, each heat dissipating means is formed integrally with the stator core. According to a third aspect of the present invention, each heat dissipating means is made of the same member as at least one of the plurality of annular plates constituting the stator core.
According to these, the number of parts can be reduced, the number of assembling steps can be reduced, and the manufacturing cost can be reduced.

In the invention according to claim 4, each heat radiation means is in contact with the stator core in the axial direction. In the invention according to claim 5, each heat dissipating means is fitted in the annular recess of the outer diameter wall of the stator core.
According to these, each heat radiating means can be brought into contact with the stator core over a wide range, and more heat of the stator core can be conducted to the heat radiating means.

In the invention according to claim 6, each heat radiating means has a plate shape having a thickness in the axial direction, a first heat radiating surface on one side in the axial direction, a second heat radiating surface on the other side in the axial direction, and a diameter. It has a third heat radiating surface in the outward direction.
According to this, since the heat radiation surface is formed in a wide range, the heat radiation performance can be effectively enhanced.

In a seventh aspect of the invention, the housing includes a first housing located on one side in the axial direction with respect to each heat radiating means, and a second housing located on the other side in the axial direction with respect to each heat radiating means. Each heat dissipating means is sandwiched between the first housing and the second housing, and is fastened together with a screw for fixing the first housing and the second housing.
According to this, it is not necessary to separately provide a fixing member for fixing the heat dissipating means, and the number of parts can be reduced.

  In the invention according to claim 8, the first housing and the second housing are made of resin. Also, a metal insert collar is embedded in one of the first housing and the second housing so that the screw is inserted and sandwiched between the heat radiating means and the head of the screw. In addition, a metal insert nut is embedded in the other of the first housing and the second housing so as to be screwed into contact with the heat dissipation means and exposed to the outside of the housing.

  According to this, the first heat conduction path formed by the stator core and the heat radiation means, the second heat conduction path formed by the stator core, the heat radiation means and the insert nut, and the stator core, the heat radiation means, the insert collar, and the screw. Since it has the 3rd heat conduction path which a head forms, heat dissipation can be improved more effectively.

It is a figure which shows the shift-by-wire system using the rotary actuator by 1st Embodiment of this invention. It is a longitudinal cross-sectional view which shows the rotary actuator by 1st Embodiment of this invention. It is the III-III sectional view taken on the line of FIG. It is a figure which expands and shows the arrow IV part of FIG. 2, Comprising: It is a figure which shows each heat conduction path. It is a longitudinal cross-sectional view which shows the rotary actuator by 2nd Embodiment of this invention. It is the VV sectional view taken on the line of FIG. It is a longitudinal cross-sectional view which shows the rotary actuator by 3rd Embodiment of this invention.

Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In the embodiments, substantially the same components are denoted by the same reference numerals and description thereof is omitted.
(First embodiment)
The rotary actuator according to the first embodiment of the present invention is used as a drive unit of the shift-by-wire system shown in FIG. The shift-by-wire system 1 has a function of switching the shift range of the automatic transmission for the vehicle by operating the manual valve 2 and a function of locking the rotation of the automatic transmission by restricting the rotation of the parking gear 4. . First, the shift-by-wire system 1 will be described.

As shown in FIG. 1, the shift-by-wire system 1 includes an electronic control device 5, a rotary actuator 15, a control rod 6, a detent mechanism 7, and a parking mechanism 11.
The electronic control unit 5 operates the rotary actuator 15 according to the operation position of a not-shown select lever operated by the driver. The rotary actuator 15 drives the control rod 6 to rotate. The control rod 6 rotates integrally with the output shaft of the rotary actuator 15.

  The detent mechanism 7 includes a detent plate 8 that rotates integrally with the control rod 6, and a detent spring 10 that fixes the rotational position of the detent plate 8. The detent plate 8 has an engagement protrusion 9 that can be engaged with the valve member 3 of the manual valve 2 in the axial direction, and moves the valve member 3 in the axial direction according to the rotational position. As a result, the shift range of the automatic transmission is switched.

  The parking mechanism 11 includes a parking lock pole 12 that can approach and separate from the parking gear 4, a park rod 13 that moves in a direction parallel to the axis of the parking gear 4 according to the rotational position of the detent plate 8, and the park rod 13 Is formed of a cam member 14 that causes the parking lock pole 12 to approach and separate from the parking gear 4 in accordance with the movement. The cam member 14 moves the parking lock pole 12 to a position where it engages with the parking gear 4 when the detent plate 8 rotates to a predetermined parking position. As a result, the rotation of the output shaft of the automatic transmission that rotates integrally with the parking gear 4 is locked.

Next, the configuration of the rotary actuator 15 will be described in detail with reference to FIGS.
2 and 3, the rotary actuator 15 includes a housing 20, a switched reluctance motor (hereinafter referred to as "SR motor") 40, a reduction gear 60, an output shaft 70, a bracket 75, and a metal plate for heat dissipation. 80 etc.

The housing 20 includes a rear housing 21 and a front housing 30.
The rear housing 21 is made of resin and includes a bottomed cylindrical portion 22, a connector portion 23, and a plurality of fixing portions 24. A metal stator holding member 25 formed in a bottomed cylindrical shape is embedded in the bottomed cylindrical portion 22. The connector part 23 has a plurality of terminals 26 that can be connected to the electronic control unit 5 of FIG. Each fixing portion 24 is formed so as to protrude outwardly from the bottomed cylindrical portion 22. A metal insert nut 27 is embedded in the fixed portion 24.

  The front housing 30 is made of resin and includes a bottomed cylindrical portion 31, an output portion 32, and a plurality of fixing portions 34. The bottomed tube portion 31 is positioned so as to be coaxial with the bottomed tube portion 22, and is disposed so that the open end portion is positioned on the bottomed tube portion 22 side. The output part 32 is formed in a cylindrical shape so as to protrude from the center of the bottom part of the bottomed cylindrical part 31 to the side opposite to the rear housing 21. The output part 32 and the bottom part of the bottomed cylinder part 31 have a common through-hole 33. Each fixing portion 24 is formed to protrude radially outward from a position corresponding to the fixing portion 24 in the circumferential direction of the bottomed cylindrical portion 31. A metal insert collar 35 is embedded in the fixed portion 24. The insert collar 35 has a screw insertion hole 36 coaxial with the screw hole 28 of the insert nut 27.

The front housing 30 is fixed to the rear housing 21 with screws 37 in a state where a metal plate 80 for heat dissipation is sandwiched between the front housing 30 and the rear housing 21. The screw 37 is inserted into the screw insertion hole 36 of the insert collar 35 and screwed into the screw hole 28 of the insert nut 27. The inner space of the housing 20 is a space outside the housing by a seal member 38 provided between the front housing 30 and the heat radiating metal plate 80 and a seal member 39 provided between the rear housing 21 and the heat radiating metal plate 80. Is sealed.
The bracket 75 is for attaching the housing 20 to a transmission case (not shown), for example, and is fixed to the outer wall at the bottom of the front housing 30 with screws 37.

The SR motor 40 is a three-phase brushless motor and includes a stator 41 and a rotor 48.
The stator 41 has a stator core 42, a U-phase coil 45, a V-phase coil 46 and a W-phase coil 47. The stator core 42 includes a ring portion 43 fitted to the inner diameter wall of the stator holding member 25, and a plurality of teeth portions 44 protruding from the ring portion 43 in the inner diameter direction. As shown in FIG. 3, twelve teeth portions 44 are formed at equal intervals in the circumferential direction. As shown in FIG. 2, the stator core 42 is formed by laminating a plurality of annular plates including the heat radiating metal plate 80 in the plate thickness direction.

U-phase coil 45, V-phase coil 46, and W-phase coil 47 are each composed of a conductive wire wound around each tooth portion 44. Four U-phase coils 45, four V-phase coils 46 and four W-phase coils 47 are provided, and one U-phase coil, one V-phase coil and one W-phase coil are arranged in the circumferential direction.
Each of the coils 45 to 47 is electrically connected to the bus bar portion 57. As shown in FIG. 2, the bus bar portion 57 is provided on the bottom side of the rear housing 21 with respect to the stator 41. The bus bar portion 57 is formed of a thin metal plate, for example, and is electrically connected to the terminal 26 of the connector portion 23. A current is supplied to each of the coils 45 to 47 via the bus bar portion 57.

  The rotor 48 is provided in the radially inward direction of the stator 41 and has a rotor shaft 49 and a rotor core 54. The rotor shaft 49 has one end 50 on the bottom side of the front housing 30 rotatably supported by the front bearing 58 and the other end 51 on the bottom side of the rear housing 21 rotatably supported by the rear bearing 59. Further, the rotor shaft 49 forms a rotor core fixing portion 52 and an eccentric portion 53 in order from the one end portion 50 side between the one end portion 50 and the other end portion 51. The one end portion 50, the rotor core fixing portion 52, and the other end portion 51 are arranged coaxially with each other, and the eccentric portion 53 is arranged so as to be eccentric with respect to the rotor core fixing portion 52.

  The rotor core 54 includes a boss portion 55 fixed to the outer diameter wall of the rotor core 54 of the rotor shaft 49 by press-fitting, for example, and a plurality of salient poles 56 protruding from the boss portion 55 in the radially outward direction. As shown in FIG. 3, eight salient poles 56 are formed at equal intervals in the circumferential direction. As shown in FIG. 2, the rotor core 54 is formed by laminating a plurality of plates in the thickness direction.

The reduction gear 60 is a kind of so-called planetary gear device, and includes a ring gear 61 and a planetary gear 62.
The ring gear 61 is an annular internal gear that is positioned radially outward of the eccentric portion 53 of the rotor shaft 49 and is arranged coaxially with the one end portion 50 and the other end portion 51 of the rotor shaft 49. The ring gear 61 is fixed to the inner diameter wall of the bottomed cylindrical portion 22 of the front housing 30.

The planetary gear 62 is an external gear that is positioned in the radially inward direction of the ring gear 61, is arranged coaxially with the eccentric portion 53 of the rotor shaft 49, and meshes with the ring gear 61. The planetary gear 62 is supported by the middle bearing 64 so as to be capable of rotating about the eccentric portion 53 and revolving around the rotation axis of the rotor shaft 49.
The planetary gear 62 forms a plurality of torque transmission protrusions 63 protruding to the opposite side of the rotor core 54. The torque transmission protrusions 63 are formed at equal intervals around the rotation axis of the planetary gear 62. The torque transmission protrusion 63 functions as a rotation transmission means for transmitting the rotation component of the planetary gear 62 to the output shaft 70 together with a torque transmission hole 73 described later.

  The output shaft 70 includes a shaft portion 71 and a flange portion 72. The shaft portion 71 is disposed on the rotation shaft of the rotor shaft 49 and is rotatably supported by the output portion 32 of the front housing 30. The flange portion 72 is formed integrally with an end portion of the shaft portion 71 on the planetary gear 62 side. The flange portion 72 has a plurality of torque transmission holes 73 into which the torque transmission protrusions 63 of the planetary gear 62 are loosely fitted. The torque transmission holes 73 are formed at equal intervals around the rotation axis of the rotor shaft 49, that is, around the revolution axis of the planetary gear 62, and constitute a rotation transmission means together with the torque transmission hole 73. The output shaft 70 is coupled to the one end portion 50 of the rotor shaft 49 through the speed reducer 60 and the rotation transmitting means so as to be able to transmit torque.

  The heat radiating metal plate 80 is sandwiched between a plurality of annular plates constituting the stator core 42, and together with these annular plates, a core portion 81 that forms the ring portion 43 and the teeth portion 44 of the stator core 42, and the core portion 81. Three projections 82, 83, 84 project radially out of the housing 20. The heat radiating metal plate 80 is sandwiched between the front housing 30 and the rear housing 21 and fastened to the screw 37 together. The heat radiation metal plate 80 can directly conduct the heat of the stator core 42 without passing through, for example, air or a resin member.

  Protruding portion 82 is positioned radially outward with respect to any one of each U-phase coil 45 and is formed integrally with stator core 42. Protrusion 83 is formed radially outward with respect to any one of each V-phase coil 46. Protrusion 84 is formed radially outward with respect to any one of W phase coils 47. These protrusions 82, 83, and 84 are arranged at equal intervals in the circumferential direction. Hereinafter, when the protrusions 82, 83, 84 are not particularly distinguished, they are simply referred to as “projections”. The protrusions of the heat radiating metal plate 80 are plate-shaped with a thickness in the axial direction, the first heat radiating surface 85 on one side in the axial direction, the second heat radiating surface 86 on the other side in the axial direction, and the radially outward direction. The third heat radiation surface 87 is provided.

The insert collar 35 is sandwiched between the heat radiating metal plate 80 and the head of the screw 37. The head of the screw 37 is exposed to the outside of the housing 20 and has a fourth heat radiating surface 88 capable of radiating heat conducted from the heat radiating metal plate 80 via the insert collar 35.
One end of the insert nut 27 is in contact with the metal plate 80 for heat dissipation, and the other end is exposed outside the housing 20. The insert nut 27 has a fifth heat radiating surface 89 capable of radiating heat directly conducted from the heat radiating metal plate 80.

  As shown by an arrow X in FIG. 4, the stator core 42 and the heat radiating metal plate 80 form a first heat conduction path. Further, as indicated by an arrow Y in FIG. 4, the stator core 42, the heat radiating metal plate 80, and the insert nut 27 form a second heat conduction path. Further, as indicated by an arrow Z in FIG. 4, the stator core 42, the heat radiating metal plate 80, the insert collar 35, and the heads of the screws 37 form a third heat conduction path. The protrusions of the heat radiating metal plate 80, the insert nuts 27, and the heads of the screws 37 function as “heat radiating means” for radiating heat conducted from the stator core 42 to the outer space of the housing 20.

In the rotary actuator 15 configured as described above, when the energization is switched in the order of the U-phase coil 45, the V-phase coil 46, and the W-phase coil 47, the rotor 48 rotates counterclockwise in FIG. When the energization is switched in the order of the V-phase coil 46 and the U-phase coil 45, the rotor 48 rotates clockwise in FIG. The rotor 48 rotates 45 degrees each time energization of the U-phase coil 45, the V-phase coil 46, and the W-phase coil 47 is completed.
When the rotor 48 rotates as described above, the planetary gear 62 revolves around the rotation axis of the rotor shaft while rotating around the eccentric portion of the rotor shaft 49 by rolling on the inner diameter wall of the ring gear 61. At this time, the planetary gear 62 rotates at a reduced speed with respect to the rotor shaft 49.

When the planetary gear 62 rotates as described above, the rotation component of the planetary gear 62 is transmitted to the output shaft 70 via the torque transmission protrusion 63 and the torque transmission hole 73. The output shaft 70 outputs this rotation to the control rod 6.
Heat generated by energizing each coil is conducted from the stator core 42 through the heat radiating metal plate 80 to the protrusions of the heat radiating metal plate 80, the insert nuts 27, and the heads of the screws 37. Heat is radiated from surfaces 85-89.

As described above, the rotary actuator 15 according to the first embodiment includes the SR motor 40 including the rotor 48 and the stator 41, the resin housing 20 that houses the SR motor 40, and the heat radiating metal plate 80. Prepare.
The heat radiating metal plate 80 includes a core portion 81 that constitutes the stator core 42, and three projecting portions 82, 83, and 84 that project radially from the core portion 81 to the outside of the housing 20.

  Protruding portion 82 is positioned radially outward with respect to any one of each U-phase coil 45 and is formed integrally with stator core 42. Protrusion 83 is formed radially outward with respect to any one of each V-phase coil 46. Protrusion 84 is formed radially outward with respect to any one of W phase coils 47. These protrusions 82, 83, and 84 are arranged at equal intervals in the circumferential direction. Heat of the stator core 42 can be directly conducted to the protrusions 82, 83, and 84. These protrusions 82, 83, 84 function as “heat dissipating means” for dissipating heat conducted from the stator core 42 to the space outside the housing 20.

  According to such a rotary actuator 15, the stator core 42 and the heat radiating metal plate 80 form a first heat conduction path for conducting the heat of each coil to the outside of the housing 20 for heat radiation. Most of the heat generated in each coil is radiated to the outside of the housing 20 via the first heat conduction path without passing through the resin housing 20. Thereby, high heat dissipation can be obtained, and the rise in temperature in the housing 20 can be suppressed. Therefore, the restriction on the number of continuous operations of the SR motor 40 can be relaxed, and a decrease in the output torque of the SR motor 40 due to an increase in the electrical resistance of each coil can be suppressed.

  Moreover, the protrusion part of the metal plate 80 for thermal radiation is provided one for every phase coil. Thereby, the amount of heat radiation can be made uniform for each phase coil. Therefore, the strength of the magnetic field generated by each phase coil can be made uniform in the rotation direction, and the pulsation of the output torque of the SR motor 40 can be suppressed.

Moreover, in 1st Embodiment, the metal plate 80 for heat dissipation is integrally formed from the core part 81 which comprises the stator core 42, and the projection parts 82, 83, and 84 as a thermal radiation means. That is, the projecting portions 82, 83, 84 of the heat radiating metal plate 80 are made of the same member as the core portion 81 constituting the stator core 42 and are formed integrally with the stator core 42.
According to this, compared with the case where the protrusion part of the metal plate 80 for heat dissipation is formed separately from the stator core 42, the number of parts can be reduced, the number of assembling steps can be reduced, and the manufacturing cost can be reduced.

In the first embodiment, the protrusions 82, 83, 84 of the heat radiating metal plate 80 are plate-shaped with a thickness in the axial direction, and the first heat radiating surface 85 on one side in the axial direction and the other in the axial direction. A second heat radiating surface 86 on the side and a third heat radiating surface 87 in the radially outward direction.
According to this, since the heat radiation surface is formed in a wide range, the heat radiation performance can be effectively enhanced.

In the first embodiment, the heat radiating metal plate 80 is sandwiched between the front housing 30 and the rear housing 21 and fastened together with the screw 37.
According to this, it is not necessary to separately provide a fixing member for fixing the heat radiating metal plate 80, and the number of parts can be reduced.

In the first embodiment, the insert collar 35 is sandwiched between the heat radiating metal plate 80 and the head of the screw 37. The head of the screw 37 has a fourth heat radiating surface 88 capable of radiating heat conducted from the heat radiating metal plate 80 via the insert collar 35. The insert nut 27 has a fifth heat radiating surface 89 whose one end abuts against the heat radiating metal plate 80 and whose other end is exposed to the outside of the housing 20 and can radiate heat directly conducted from the heat radiating metal plate 80. ing.
According to this, the second heat conduction path formed by the stator core 42, the heat radiating metal plate 80, and the insert nut 27, and the stator core 42, the heat radiating metal plate 80, the insert collar 35, and the head of the screw 37 are formed. Since it has the 3rd heat conduction path to form, heat dissipation can be improved effectively.

(Second Embodiment)
Next, the rotary actuator according to the second embodiment will be described with reference to FIGS.
As shown in FIGS. 5 and 6, in the second embodiment, the heat radiating metal plate 90 is formed in an annular shape and is fixed to the radially outer wall of the stator core 92 by, for example, press fitting. This heat radiating metal plate 90 has projections 82, 83, 84 and three connection portions 91 that connect the projections 82, 83, 84 to each other. The protrusions 82, 83, and 84 are in contact with the stator core 92 at the radially inner surface. The heat dissipating metal plate 90 can directly conduct the heat of the stator core 92 without passing through, for example, air or a resin member.

According to the rotary actuator including such a heat radiating metal plate 90, the heat generated in each coil is radiated from the heat radiating surfaces of the protrusions of the heat radiating metal plate 90 via the stator core 92 and the heat radiating metal plate 90. Therefore, heat dissipation can be improved like the first embodiment.
Moreover, it is the same as that of 1st Embodiment that the projection part of the metal plate 90 for heat dissipation can be equalized for every phase coil by providing one projection part for every phase coil. Thereby, the strength of the magnetic field generated by each phase coil can be made uniform in the rotation direction, and the pulsation of the motor output torque can be suppressed.

(Third embodiment)
Next, a rotary actuator according to a third embodiment will be described with reference to FIG.
As shown in FIG. 7, in the third embodiment, the heat radiating metal plate 95 includes protrusions 82, 83, 84 that fit into an annular groove 98 provided on the outer diameter wall of the stator core 97, and the protrusions 82, 83, It has three connection parts 96 which connect 84s. The protrusions 82, 83, and 84 are in contact with the stator core 97 on both axial surfaces and radially inner surfaces. The heat dissipating metal plate 95 can directly conduct the heat of the stator core 97 without passing through, for example, air or a resin member.
According to the rotary actuator including such a heat radiating metal plate 95, the heat generated in each coil is radiated from the heat radiating surfaces of the protrusions of the heat radiating metal plate 95 via the stator core 97 and the heat radiating metal plate 95. Therefore, heat dissipation can be improved like the first embodiment.

Moreover, it is the same as that of 1st Embodiment that the projection part of the metal plate 95 for thermal radiation is provided one for every phase coil, and can also equalize the thermal radiation amount for every phase coil. Thereby, the strength of the magnetic field generated by each phase coil can be made uniform in the rotation direction, and the pulsation of the motor output torque can be suppressed.
Further, since the protrusions of the metal plate 95 for heat dissipation are in contact with the stator core 97 on both sides in the axial direction and the surfaces in the radial direction, the protrusions are brought into contact with the stator core 97 over a wide range so that the heat of the stator core 97 is increased. More can be conducted to the protrusion.

(Other embodiments)
In other embodiments of the present invention, the number of phases of the coil may be two or four or more.
Moreover, in other embodiment of this invention, each thermal radiation means may be isolate | separated from each other in the circumferential direction, and does not need to be plate shape. Moreover, the number of the integral multiple of the number of phases of a coil may be formed in a thermal radiation means.
The stator core may be formed from a plurality of segment stator cores separated for each tooth.

In another embodiment of the present invention, the housing is not necessarily divided on both sides in the axial direction with respect to the heat radiating metal plate. For example, the metal plate for heat dissipation may be provided so as to protrude out of the housing through a through hole penetrating the housing in and out.
Moreover, in other embodiment of this invention, a rotary actuator may be used for apparatuses other than a shift-by-wire system among vehicles.
Moreover, in other embodiment of this invention, a rotary actuator does not necessarily need to be equipped with a reduction gear.

  The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from the spirit of the invention.

DESCRIPTION OF SYMBOLS 15 ... Rotary actuator 20 ... Housing 42, 92, 97 ... Stator core 43 ... Ring part 44 ... Teeth part 45 ... U-phase coil (coil)
46 ... V-phase coil (coil)
47 ... W phase coil (coil)
48 ... Rotor 80, 90, 95 ... Metal plate for heat dissipation 82, 83, 84 ... Projection (heat dissipation means)

Claims (8)

A rotatable rotor;
A stator core having a ring portion provided in a radially outward direction of the rotor, and a plurality of teeth portions protruding from the ring portion toward the rotor side and spaced apart from each other in the circumferential direction;
A multi-phase coil composed of a conductive wire wound around each tooth portion of the stator core;
A housing for accommodating the rotor, the stator core and the coils, rotatably supporting the rotor, and fixedly supporting the stator core;
The stator core projects radially out of the housing by the same number for each phase of the coil from the radially outward position with respect to the coil, and heat of the stator core can be directly conducted, and a plurality of the heat dissipating the conducted heat Metal heat dissipation means;
A rotary actuator comprising:   The rotary actuator according to claim 1, wherein each of the heat dissipating means is formed integrally with the stator core. The stator core is formed by laminating a plurality of annular plates in the axial direction,
The rotary actuator according to claim 2, wherein each of the heat dissipating means is formed of the same member as at least one of the annular plates.   The rotary actuator according to claim 1, wherein each of the heat dissipating means is in contact with the stator core in the axial direction.   5. The rotary actuator according to claim 4, wherein each of the heat dissipating means is fitted in an annular recess of the outer diameter wall of the stator core.   Each of the heat radiating means has a plate shape having a thickness in the axial direction, and includes a first heat radiating surface on one side in the axial direction, a second heat radiating surface on the other side in the axial direction, and a third heat radiating surface in the radially outward direction. It has, The rotary actuator as described in any one of Claims 1-5 characterized by the above-mentioned. The housing has a first housing located on one side in the axial direction with respect to the heat radiating means, and a second housing located on the other side in the axial direction with respect to the heat radiating means,
2. Each of the heat dissipating means is sandwiched between the first housing and the second housing, and is fastened together with a screw for fixing the first housing and the second housing. The rotary actuator according to claim 6. The first housing and the second housing are made of resin,
The screw head is exposed outside the housing;
One of the first housing and the second housing is embedded with a metal insert collar through which the screw is inserted and sandwiched between the heat radiating means and the head of the screw,
The other of the first housing and the second housing is embedded with a metal insert nut that is screwed into contact with the heat radiating means and exposed to the outside of the housing. 8. The rotary actuator according to 7.

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