JP2009296809A - Actuator drive motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve responsiveness and durability against vibration and impact in an actuator drive motor used for a throttle valve of a vehicle engine and an optical axis controller of a vehicle headlamp or the like. <P>SOLUTION: An engagement portion 1123 is constituted of inner diameter enlarged portions 1121b formed on the respective opening sides of a first cup-shaped rotor yoke 1121 and a second cup-shaped rotor yoke 1122, and an outer diameter reduced portion 1122b fitted to the inner diameter enlarged portions. A shaft 1110 is fixed at each center of two rotor yokes 1121 and 1122 to form a rotor yoke assembly 1124 while being connected via the engagement portion 1123 and integrated therewith. A magnet 1130 is fixed on the outer circumference of the rotor yoke assembly 1124 to constitute a rotor 1100 of the actuator drive motor. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a motor for driving an actuator used in a throttle valve of an automobile engine, an optical axis control device of an automobile headlamp, and the like. Specifically, it improves responsiveness and improves durability against vibration and impact. Relates to the structure of the rotor.

  Motors for driving actuators used in automotive engine throttle valves and automotive headlamp optical axis control devices are required to have good responsiveness and durability against vibration and impact. Therefore, steel plates are used for the rotor yoke. Thus, a motor has been devised in which the moment of inertia and weight of the rotor is reduced to improve the response and the durability against vibration / impact is improved (for example, see Patent Document 1).

  FIG. 7 shows the structure of the motor described in Patent Document 1. In FIG. 7, the stator is constituted by an iron core 8002 fixed to the inner peripheral surface of a yoke bracket 8001 and wound, and the rotor has magnetic plate members 8022 and 8023 formed in a hollow annular shape as a rotor yoke, and the outer peripheral surface thereof. A cylindrical magnet 8021 is fixed to the shaft, and the shaft 8006 is fixed to pass through the center portions of the magnetic plate members 8022 and 8023. Further, bearings 8007 for rotatably supporting the shaft 8006 of the rotor are disposed at two positions on both ends of the yoke bracket 8001.

  In the motor described in Patent Document 1, the rotor yoke is formed in a hollow ring shape using a magnetic plate material, so that the moment of inertia is reduced to improve the startability and responsiveness, and the lightweight rotor is supported at two locations outside the rotor yoke. Therefore, the structure is strong against vibration and shock.

  FIG. 9 shows another motor structure (second example) in practical use. FIG. 9 shows a brushless motor in which electronic components are mounted inside the motor.

  In FIG. 9, the stator is constituted by an iron core 1210 fixed to the inner peripheral surface of a frame 1410 and provided with a winding 1220, and a rotor 1100 is obtained by stacking rotor yokes 1121 and 1122 formed in a cup shape in the same direction. Is a rotor yoke, and a shaft 1110 is fixed through the center of the rotor yoke 1121, 1122, and a cylindrical magnet 1130 is fixed to the outer peripheral surface thereof. Further, a thrust ring 1140 is fixed to the shaft 1110 and constitutes a thrust bearing together with the bearing 1302.

  The thrust ring 1140 sets a space H101 in the shaft penetrating direction for mounting an electronic component on the printed circuit board 1510, and the diameter D102 of the hole formed in the printed circuit board 1510 is set to a minimum diameter larger than the diameter D101 of the thrust ring. By setting, the mounting area of the electronic parts is secured.

Further, bearings 1301 and 1302 for supporting the shaft 1110 of the rotor 1100 are arranged on the frames 1410 and 1420, and the rotor 1100 is rotatably held. A magnetoelectric conversion element 1521 for detecting the magnetic pole position of the magnet 1130 is mounted on the printed circuit board 1510 and sends a rotor magnetic pole position signal to a motor drive circuit (not shown) to generate a predetermined torque in the motor. It is configured like this.
Japanese Utility Model Publication No. 1-64969 (microfilm of Japanese Utility Model Application No. 62-158767)

  However, in the conventional configuration shown in Patent Document 1, the rotor yoke is divided into two parts so that the rotor magnet cannot be assembled due to the difference in the direction (phase) of the outer periphery of the two parts, or the rotor There was a problem of causing a balance.

  FIG. 8 is a diagram for explaining this problem. 8 is a diagram in which a part of the rotor of FIG. 7 is extracted, and the same components as those in FIG. 7 are denoted by the same reference numerals as those in FIG.

  In FIG. 8, when the shaft 8006 is fixed to the magnetic plates 8022 and 8023 by a method such as press-fitting or bonding, it is very rare that both are fixed in a state of zero perpendicularity, and both have a certain inclination. It is fixed with. Since the magnitude and direction (phase) of this inclination differ for each of the magnetic plates 8022 and 8023, the effective outer diameter D93 of the rotor is larger than the outer diameters D91 and D92 of the magnetic plates 8022 and 8023, respectively. Therefore, there is a problem that it is impossible to assemble the cylindrical magnet 8021 having an inner diameter slightly larger than D91 and D92 so as to be fitted to the rotor yoke.

  In addition, the inclination of the shaft 8006 and the magnetic plate members 8022 and 8023 causes the outer periphery of the magnetic plate members 8022 and 8023 to oscillate, causing a problem of causing rotor unbalance.

  An object of the present invention is to solve such a conventional problem, and to provide a motor in which the moment of inertia and weight of the rotor is reduced to increase the response and the durability against vibration and impact is improved. To do.

  In addition, the configuration of another motor that is described as a second example and put into practical use not only causes the same problem as in the case of Patent Document 1, but also requires a new thrust ring 1140, which increases the number of parts. In addition, since the durability against vibration and impact depends on the fixing force for fixing the thrust ring 1140 to the shaft 1110, there is a problem that reliability is lowered.

  The present invention solves these problems, and reduces the moment of inertia and weight of the rotor without increasing the number of parts or reducing the reliability, thereby improving the response and durability against vibration and impact. An object of the present invention is to provide a motor with improved performance.

  In order to solve the above-described problems, the present invention includes at least a cup-shaped first rotor yoke and a second rotor yoke, and an engaging portion is formed on the opening side of the two rotor yokes. The two rotor yokes are connected to each other, and a shaft is fixed to the center of each of the two connected rotor yokes to form a rotor yoke assembly, and a magnet is fixed to the outer periphery of the rotor yoke assembly to provide a rotor for the actuator drive motor. Is configured.

  Further, an inner diameter enlarged portion is provided on the opening side of the first rotor yoke, and an outer diameter reduced diameter portion that is fitted to the inner diameter enlarged portion is provided on the opening side of the second rotor yoke, and the engagement is engaged with each other. Part.

In addition to the above configuration, a printed circuit board on which a magnetoelectric conversion element for detecting the magnetic pole position of the magnet fixed to the rotor is mounted is provided, and a protruding portion having a diameter smaller than the inner diameter of the magnet is provided on the rotor yoke facing the printed circuit board. And a hole larger than the protruding portion of the rotor is provided in the center of the printed circuit board so as to penetrate the protruding portion of the rotor, and an end surface of the protruding portion is used as a thrust bearing member.

  ADVANTAGE OF THE INVENTION According to this invention, the responsiveness of the motor for actuator drive used for the throttle-axis of a motor vehicle engine, the optical-axis control apparatus of the headlight of a motor vehicle, etc. can improve the durability with respect to a vibration and an impact.

  According to the first and second aspects of the present invention, since the shaft is fixed in a state where the two cup-shaped rotor yokes are connected via the engaging portion, the outer peripheral deflection phases of the two rotor yokes coincide with each other. The rotor magnet is not made impossible to assemble because of the correction.

  Further, by connecting the two rotor yokes by the engaging portion, the outer peripheral runout of the two rotor yokes is corrected and offset, and the rotor unbalance is reduced.

  Further, since the openings of the two rotor yokes are connected and integrated, the rigidity of the rotor yoke assembly is improved, and the durability against vibration and shock of the motor can be improved. In addition, since the rigidity of the rotor yoke assembly is improved, the rotor yoke can be made thinner and lighter than before, so that the responsiveness can be further improved.

  In addition to the effects of the inventions described in claims 1 and 2, the invention described in claim 3 is provided with a protrusion for fixing the shaft to only one of the two cup-shaped rotor yokes. When the two rotor yokes are connected by the connecting member, the outer runout of the rotor yoke on the side without the protruding portion is the outer periphery of the rotor yoke on the side where the protruding portion is provided. Since it is corrected and corrected in accordance with the run-out, the rotor magnet can not be assembled.

  Further, the outer peripheral runout of the two rotor yokes is corrected and offset, and the rotor unbalance is reduced.

  In addition to the effects of the inventions described in the first to third aspects, the invention described in claim 4 is formed by forming the height of the rotor yoke provided with the protrusions to be equal to or less than the diameter. Since the outer peripheral runout on the opening side of the rotor yoke provided with can be reduced, the outer peripheral runout of the other rotor yoke to be corrected and corrected accordingly can be further reduced.

  According to the fifth aspect of the present invention, in addition to the effects of the first to fourth aspects of the present invention, the second rotor yoke is formed with a protruding portion whose diameter is smaller than the outer diameter of the portion where the magnet is fixed. As a result, the hole diameter of the printed circuit board can be reduced, so that the mounting area of the electronic component can be increased. In addition, since there is no protruding portion, it is possible to obtain an operation and effect that it becomes easy to obtain accuracy such as flatness and squareness of a portion functioning as a thrust bearing.

  According to the sixth aspect of the present invention, in the motor according to the fifth aspect, it is possible to accurately set an end play when the end face of the rotor yoke assembly is used as a thrust bearing member. This has the effect of further enhancing durability against vibration.

  According to a seventh aspect of the present invention, there is provided an actuator used in a throttle valve of an automobile engine, an optical axis controller device of a headlight of an automobile, and the like by using the motor having the structure described in any one of the first to sixth aspects. Not only can the rotor moment of inertia of the drive motor be reduced, improving the response of the actuator, but also reducing the weight of the rotor of the motor, which is the heaviest component of the actuator and is vulnerable to vibration and shock. Therefore, the durability of the actuator against vibration and impact can be improved.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a sectional structural view of a motor according to Embodiment 1 of the present invention.

  In FIG. 1, a stator constituted by an iron core 1210 provided with a winding 1220 is fixed to an inner peripheral surface of a frame 1410 (same as the yoke bracket 8001 in FIG. 7). Then, the first rotor yoke 1121 and the second rotor yoke 1122 formed in a cup shape are opposed to the inner peripheral side of the stator, and the shafts are fixed through the centers of the first rotor yoke 1121 and the second rotor yoke 1122. A rotor yoke assembly 1124 formed by 1110 is disposed.

  An inner diameter enlarged portion 1121b is formed on the opening side of the first rotor yoke 1121, and an outer diameter reduced diameter portion 1122b fitted to the inner diameter enlarged portion 1121b is formed on the opening side of the second rotor yoke 1122. . The inner diameter enlarged portion 1121b and the outer diameter reduced diameter portion 1122b constitute an engaging portion 1123. While the outer diameter reduced diameter portion 1122b is engaged and inserted into the inner diameter enlarged portion 1121b, the openings of the two rotor yokes 1121 and 1122 are opened. The end faces are connected facing each other.

  A cylindrical magnet 1130 is fixed to the outer peripheral surface of the rotor yoke assembly 1124 to constitute the rotor 1100. Further, bearings 1301 and 1302 for supporting the shaft 1110 of the rotor 1100 are arranged on the frames 1410 and 1420, and the rotor 1100 is rotatably held.

  FIG. 2A shows the details of the rotor yoke assembly 1124 including the first rotor yoke 1121, the second rotor yoke 1122, and the shaft 1110 shown in FIG. 1, and the first rotor yoke 1121 and the second rotor at the engaging portion 1123. FIG. 10 is a cross-sectional structure diagram for explaining an assembling method for engaging / connecting the rotor yoke 1122 with each other.

  In FIG. 2A, the first rotor yoke 1121 and the second rotor yoke 1122 formed in a cup shape are formed with protrusions 1121a and 1122a for fixing (press-fitting) the shaft 1110 at the center. As described above, the inner diameter enlarged portion 1121b formed on the opening side of the first rotor yoke 1121 and the outer diameter formed on the opening side of the second rotor yoke 1122 so as to be fitted to the inner diameter enlarged portion 1121b. An engagement portion 1123 is constituted by the reduced diameter portion 1122b. Then, before the shaft 1110 is fixed to the protruding portions 1121a and 1122a by press-fitting or the like, the engagement portion 1123 is connected with the end surfaces of the openings facing each other while engaging and inserting the two rotor yokes 1121 and 1122.

At this time, the outer diameter reduced portion 1122b of the second rotor yoke of the engaging portion 1123 is set slightly smaller than the diameter of the inner diameter enlarged portion 1121b of the first rotor yoke 1121, so that the first rotor yoke 1121 and the second rotor yoke 1121 The rotor yoke 1122 can be integrated with the shake phase of the outer periphery of the opening being matched. Thereafter, the shaft 1110 passes through the centers of the protruding portions 1121a and 1122a of the two rotor yokes 1121 and 1122, and is fixed by press-fitting or the like.

  According to such a configuration, the first rotor yoke 1121 and the second rotor yoke 1122 are connected and integrated by the engaging portion 1123 so that the rotor magnet cannot be assembled.

  Further, the vibration of the outer periphery of the opening of the first rotor yoke 1121 and the second rotor yoke 1122 is corrected, and the unbalance of the rotor 1100 is reduced, so that vibration and noise during operation are reduced. Then, the rigidity can be increased by integrating with the engaging portion 1123. Further, since the rotor yoke assembly 1124 is integrally formed, there is no fixed portion that may move even when a vibration or impact is applied in the thrust direction, so that vibration can be achieved without increasing the number of parts constituting the motor. -It has the effect of realizing a brushless motor with high durability against impact. Furthermore, it is possible to realize an excellent motor having distinctive features such as a hollow rotor structure and high responsiveness due to a small moment of inertia, and high durability against vibration and impact due to the light weight and high rigidity of the rotor. .

  In the above embodiment, the example in which the rotor yoke assembly 1124 is formed by connecting and integrating the first rotor yoke 1121 and the second rotor yoke 1122 directly by the engaging portion 1123 is shown. It is not limited. For example, as shown in FIG. 2B, a connection ring 1125 is disposed between the first rotor yoke 1121 and the second rotor yoke 1122, and one opening of the connection ring 1125 and the first rotor yoke 1121. Engaging portions 1123 are formed in the opening, the other opening of the connecting ring 1125, and the opening of the second rotor yoke 1122, respectively, and the first rotor yoke 1121 and the second rotor 1123 are formed by these two engaging portions 1123. The rotor yoke 1122 may be integrated by connecting and integrating the rotor yoke 1122 via the connecting ring 1125.

  In the embodiment shown in FIG. 2B, the inner diameter enlarged portion 1125a is formed at the open portions at both ends of the connecting ring 1125, and the first rotor yoke 1121 and the opening portion of the second rotor yoke 1122 are respectively provided on the opening side. The outer diameter reduced diameter portions 1121c and 1122b are formed so as to be fitted to the inner diameter enlarged portion 1125a to constitute the engaging portion 1123. In this configuration, the first rotor yoke 1121 and the second rotor yoke 1122 can have the same shape, so only one type of mold is required to manufacture the rotor yoke. This mold is advantageous in terms of product accuracy, mold durability, and mold cost because it requires only a small depth when the rotor yoke is formed in a cup shape.

(Embodiment 2)
FIG. 3 is a sectional view showing the structure of the rotor yoke assembly of the motor according to the second embodiment of the present invention.

  In FIG. 3, the second rotor yoke 1122 formed in a cup shape has a protruding portion 1122a for fixing the shaft 1110 at the center, while the other first rotor yoke 1121 has a protruding portion. Absent. Similarly to the first embodiment, after the two rotor yokes 1121 and 1122 are engaged and connected by the engaging portion 1123 and integrated, the shaft 1110 is inserted into the protruding portion 1122a of the second rotor yoke 1122 and the center of the first rotor yoke 1121. Is fixed by press-fitting or the like.

According to such a configuration, the first rotor yoke 1121 can be configured to have a weaker fixing force with respect to the shaft 1110 than the second rotor yoke 1122, so that in addition to the functions and effects of the first embodiment, the protruding portion There is no runout of the first rotor yoke 1121.
It is possible to achieve an effect that the correction and correction can be more easily performed in accordance with the shake of the second rotor yoke 1122 in which the protruding portion 1122a is formed.

(Embodiment 3)
FIG. 4 is a sectional structural view showing the structure of the rotor yoke assembly of the motor according to Embodiment 3 of the present invention.

  In FIG. 4, the second rotor yoke 1122 formed in a cup shape has a protruding portion 1122a for fixing the shaft 1110 at the center, while the other first rotor yoke 1121 has a protruding portion. Absent.

  Further, the second rotor yoke 1122 in which the protruding portion 1122a is formed has a height H41 that is equal to or smaller than the diameter D41, and the diameter D42 of the first rotor yoke 1121 in which the protruding portion is not formed is However, the height H42 of the rotor yoke 1122 is larger than H41.

  Then, after the two rotor yokes 1121 and 1122 are engaged and connected by the engaging portion 1123 and integrated as in the first embodiment, the shaft 1110 is connected to the protruding portion 1122a of the second rotor yoke 1122 and the first rotor yoke 1121. It is fixed by press-fitting or the like through the center.

  According to such a configuration, as in the second embodiment, the first rotor yoke 1121 can be configured to have a weaker fixing force with respect to the shaft 1110 than the second rotor yoke 1122, and the second portion 1122a in which the protruding portion 1122a is formed. Since the height H41 of the rotor yoke 1122 is formed to have a dimension equal to or smaller than the diameter D41, the deflection of the outer periphery of the opening of the second rotor yoke 1122 can be further reduced. As a result, the vibration of the first rotor yoke 1121 can be easily corrected and corrected in accordance with the vibration of the second rotor yoke 1122 in which the vibration of the outer periphery of the opening is further reduced. Can be prominent.

(Embodiment 4)
FIG. 5 is a sectional structural view of a motor according to Embodiment 4 of the present invention.

  In FIG. 5, parts having the same functions as those in FIG. 1 are given the same reference numerals as those in FIG.

  In FIG. 5, the second rotor yoke 1122 formed in a cup shape has a protruding portion 1122a for fixing the shaft 1110 at the center thereof, but the other first rotor yoke 1121 has no protruding portion. The first rotor yoke 1121 is configured so that the fixing force to the shaft 1110 is weaker than that of the second rotor yoke 1122.

  In addition, the first rotor yoke 1121 in which the protruding portion is not formed has a protruding portion having a diameter D61 smaller than the outer diameter D63 of the portion to which the magnet 1130 is fixed. This overhanging portion passes through a hole having a diameter D62 larger than that of the overhanging portion drilled in the center of the printed circuit board 1510, and an end surface is brought into contact with a bearing 1302 fixed to the frame 1420 to constitute a thrust bearing portion. ing. Similar to the first embodiment, after the two rotor yokes 1121 and 1122 are engaged and connected by the engaging portion 1123 to be integrated, the shaft 1110 is integrated with the protruding portion 1122a of the second rotor yoke 1122 and the center of the first rotor yoke 1121. Is fixed by press-fitting or the like.

  According to such a configuration, in addition to the operations and effects achieved by the first to fourth embodiments, the first rotor yoke 1121 is formed with a protruding portion whose diameter D61 is smaller than the outer diameter of the portion to which the magnet 1130 is fixed. As a result, the diameter D62 of the hole in the printed board 1510 can be reduced, so that the mounting area of the electronic component can be increased. In addition, since there is no protruding portion, it is possible to obtain an operation and effect that it becomes easy to obtain accuracy such as flatness and squareness of a portion functioning as a thrust bearing.

(Embodiment 5)
FIG. 6A is a sectional structural view showing the structure of the rotor yoke of the motor according to Embodiment 5 of the present invention, and FIG. 6B is an explanatory view for explaining the assembling method.

  In FIG. 6A, the first rotor yoke 1121 and the second rotor yoke 1122 formed in a cup shape are formed with protruding portions 1121a and 1122a for fixing the shaft 1110 by press fitting or the like at the center thereof. The inner diameter enlarged portion 1121b formed on the opening side of the first rotor yoke 1121 and the outer diameter reduced portion formed on the opening side of the second rotor yoke 1122 so as to be fitted to the inner diameter enlarged portion 1121b. 1122b constitutes an engaging portion 1123. When the shaft 1110 is fixed, as shown in FIG. 6B, the first rotor yoke 1121 and the shaft 1110 are first fixed by press-fitting or the like, and then the engagement portion 1123 is sandwiched therebetween. The second rotor yoke 1122 is fixed by press fitting or the like.

  At this time, the end surfaces of the opening portions of the two rotor yokes 1121 and 1122 are not brought into contact with each other, and the engagement portion 1123 is engaged with a clearance as shown by L71 in FIG. A shaft 1110 is fixed to the center of the rotor yokes 1121 and 1122 to constitute a rotor yoke assembly 1124.

  According to such a configuration, the L72 dimension of FIG. 6A can be set regardless of the dimensions of the first rotor yoke 1121 and the second rotor yoke 1122, and therefore the end surface of the rotor yoke assembly 1124 is used as a thrust bearing member. The end play can be set accurately. Thereby, in addition to the effect | action and effect which the said Embodiment 1-Embodiment 4 show | play, the effect that durability with respect to the vibration of a shaft and a parallel direction can be improved can be show | played.

  In the above description, the example in which the rotor yoke is configured to have a protruding portion for fixing the shaft has been described. However, the present invention can be similarly applied to a case in which parts for fixing the rotor yoke and the shaft are separately provided. It is.

The actuator driving motor according to the present invention can improve responsiveness and durability against vibration / impact, so that the actuator driving motor used in the throttle valve of the automobile engine, the optical axis control device of the headlight of the automobile, etc. Useful as a motor.
(Other example 1)
The actuator driving motor according to the present invention has a small moment of inertia of the rotor and good responsiveness. Therefore, a motor for driving a mechanism of an office device such as a printer or a copying machine where the starting characteristics are important, a joint of a manipulator or a small robot It is also useful as a drive motor.

1 is a sectional structural view showing a motor according to a first embodiment of the present invention. (A) Cross-sectional structure diagram for explaining details and an assembling method of a rotor yoke assembly composed of a rotor yoke, a connecting member and a shaft in the first embodiment of the present invention, (b) a modification of the first embodiment of the present invention. Cross-sectional structure diagram for explaining details and an assembling method of a rotor yoke assembly including an example rotor yoke, a connecting member, and a shaft Sectional structural drawing of the rotor yoke assembly comprised by the rotor yoke, the connection member, and the shaft in Embodiment 2 of this invention Sectional structural drawing of the rotor yoke assembly comprised by the rotor yoke, the connection member, and the shaft in Embodiment 3 of this invention Sectional structure figure which shows the motor by Embodiment 4 of this invention. (A) Cross-sectional structure diagram showing a rotor yoke according to a fifth embodiment of the present invention, (b) A structure of a rotor yoke assembly composed of a rotor yoke, a connecting member and a shaft according to a fifth embodiment of the present invention and an assembling method thereof. Cross-sectional structure diagram Cross-sectional structure diagram of conventional motor (Patent Document 1) The figure for demonstrating the subject of the conventional motor (patent document 1). Cross-sectional structure of a conventional motor (second example)

Explanation of symbols

1100 Rotor 1110, 8006 Shaft 1121 First rotor yoke 1122 Second rotor yoke 1121a, 1122a Protruding portion for shaft fixation 1121b First rotor yoke inner diameter enlarged portion 1121c Second rotor yoke outer diameter reduced diameter portion 1122b Second rotor yoke Rotor yoke outer diameter reduced portion 1123 engaging portion 1124 rotor yoke assembly 1125 connecting ring 1125a inner diameter enlarged portion 1130, 8021 magnet 1140 thrust ring 1210, 8002 iron core 1220 winding 1301, 1302, 8007 bearing 1410, 1420, 8001 Frame or yoke bracket 1510 Printed circuit board 1521 Magnetoelectric transducer 8022, 8023 Rotor yoke H41, H42, H101 Height D63 Mug Tsu DOO fixed outer diameter D91, D92, D93 outer diameter D41, D42, D61, D62, D101, D102 diameter L71, L72 dimensions

Claims (7)

At least a cup-shaped first rotor yoke and a second rotor yoke are provided, an engagement portion is formed on the opening side of the two rotor yokes, and the two rotor yokes are connected and connected via the engagement portions. A rotor having a magnet fixed to the outer periphery of a rotor yoke assembly formed by fixing a shaft to the center of each of the two rotor yokes, and a stator made of an iron core disposed opposite to the magnet and provided with windings; A brushless motor comprising a bearing for supporting the shaft of the rotor and a frame for interposing the stator and holding the bearing at both ends. An inner diameter enlarged portion is provided on the opening side of the first rotor yoke, an outer diameter reduced diameter portion that is fitted to the inner diameter enlarged portion is provided on the opening side of the second rotor yoke, and engaging portions that are engaged with each other are provided. The brushless motor according to claim 1 constituted. The brushless motor according to claim 2, wherein a protruding portion for fixing the shaft to only one of the two rotor yokes is provided. 4. The brushless motor according to claim 3, wherein the height of the rotor yoke provided with the protruding portion is formed equal to or less than the diameter, and the height of the other rotor yoke is formed larger than the height of the rotor yoke provided with the protruding portion. Provided with a printed circuit board on which a magnetoelectric conversion element for detecting the magnetic pole position of the magnet fixed to the rotor is mounted, and a protruding portion having a diameter smaller than the outer diameter of the portion to which the magnet is fixed is provided on the rotor yoke facing the printed circuit board The center of the printed circuit board is provided with a hole larger than the protruding portion of the rotor yoke so as to pass through the protruding portion of the rotor yoke, and the end surface of the protruding portion is used as a thrust bearing member. The brushless motor according to the item. 6. The brushless motor according to claim 5, wherein the rotor yoke assembly is formed by connecting the opening end faces of the two rotor yokes in a separated state without contacting each other, and fixing the shafts. An actuator equipped with the brushless motor according to any one of claims 1 to 6.

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