JP2008220008A - Brushless motor and fluid pump device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure accuracy in detecting the magnetic pole of a Hall element even when the Hall element is surface mounted over a circuit board and thus provided in a position shifted from a sensor magnet section in the axial direction and in the radial direction. <P>SOLUTION: The edge of the outer circumferential surface 54A of the sensor magnet section 54 on the housing 28 side is formed in a chamfered shape. The edge is constructed as a magnetic flux induction surface 56 for inducing magnetic flux to a Hall element 58. With this construction, it is possible to input a lot of vertical components of magnetic flux from the magnetic flux induction surface 56 to the Hall element 58 even when the Hall element 58 is surface mounted over a circuit board 32 and thus provided in a position shifted from the sensor magnet section 54 in the axial direction and in the radial direction. As a result, it is possible to increase magnetic flux inputted to the Hall element 58 and thus ensure accuracy in detecting the magnetic pole of the Hall element 58. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a brushless motor and a fluid pump device, and more particularly, to a brushless motor configured to detect a rotational position of a rotor by a magnetic pole detection means and a fluid pump device including the brushless motor.

Conventionally, as this type of brushless motor and fluid pump device, for example, there is the following (see, for example, Patent Document 1). For example, Patent Document 1 discloses an example of a motor pump provided with a brushless motor. In this motor pump, a magnet for detecting the rotational position is provided at the end of the rotor, and a hall element is provided on the outer side in the radial direction with respect to the magnet so as to face the magnet for detecting the rotational position.
Japanese Patent Laying-Open No. 2003-129898 (FIG. 1) Japanese Patent Laying-Open No. 2005-344589 (FIGS. 1 and 2) JP 2006-183669 A (FIG. 3) Japanese Utility Model Publication No. 3-117363 (FIGS. 1 and 4)

  By the way, in the motor pump described in Patent Document 1, since the Hall element is disposed in a radial direction opposite to the rotational position detection magnet, a large amount of magnetic flux is input to the Hall element from the rotational position detection magnet. The magnetic pole detection accuracy of the Hall element can be ensured. However, in the motor pump described in Patent Document 1, for example, when the Hall element is provided at a position shifted in the axial direction and the radial direction with respect to the magnet for detecting the rotational position, the magnet for detecting the rotational position is changed to the Hall element. There is a possibility that the input magnetic flux is reduced and the magnetic pole detection accuracy of the Hall element is lowered. Therefore, there is room for improvement in order to ensure the magnetic pole detection accuracy of the magnetic pole detection means even if the Hall element is provided at a position shifted in the axial direction and the radial direction with respect to the magnet for detecting the rotational position.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to detect the magnetic pole of the magnetic pole detection means even if the magnetic pole detection means is provided at a position shifted in the axial direction and the radial direction with respect to the magnet portion. It is an object of the present invention to provide a brushless motor and a fluid pump device that can ensure accuracy.

  In order to solve the above-mentioned problem, a brushless motor according to claim 1 is a stator that generates a rotating magnetic field, and a rotor that is arranged to face the stator in a radial direction and is rotated by receiving a rotating magnetic field from the stator. And a magnet portion that is provided integrally with the rotor and formed with a plurality of magnetic poles in the circumferential direction, and is provided at a position that is offset in the axial direction and the radial direction with respect to the magnet portion, and detects the position of the magnetic pole of the magnet portion. And a magnetic flux guide surface provided on the circumferential surface of the magnet portion and facing the magnetic pole detection means.

  In the brushless motor according to the first aspect, the rotor is disposed so as to face the stator in the radial direction. When a rotating magnetic field is generated in the stator, the rotor is rotated by receiving the rotating magnetic field. The rotor is integrally provided with a magnet portion having a plurality of magnetic poles formed in the circumferential direction, and a magnetic flux guiding surface is formed on the circumferential surface of the magnet portion. Then, the magnetic flux induced by the magnetic flux guiding surface is input to the magnetic pole detecting means, whereby the position of the magnetic pole of the magnet portion during rotation of the rotor is detected by the magnetic pole detecting means, and based on the detection result of the magnetic pole detecting means. By forming a rotating magnetic field of the stator, the magnet rotor is rotated at a predetermined rotational speed.

  Here, the magnetic pole detection means for detecting the position of the magnetic pole of the magnet part is provided at a position shifted in the axial direction and the radial direction with respect to the magnet part, but the magnetic flux from the magnet part is guided to the magnetic pole detection means. For this purpose, the magnetic flux guiding surface is provided on the circumferential surface of the magnet portion and faces the magnetic pole detection means. Therefore, as described above, even if the magnetic pole detecting means is provided at a position shifted in the axial direction and the radial direction with respect to the magnet part, the magnetic flux guiding surface configured to face the magnetic pole detecting means on the circumferential surface of the magnet part. Many vertical components of the magnetic flux from are input to the magnetic pole detection means. For this reason, much magnetic flux input to the magnetic pole detection means is secured.

  Thus, according to the brushless motor of the first aspect, even if the magnetic pole detection means is provided at a position shifted in the axial direction and the radial direction with respect to the magnet portion, a large amount of magnetic flux is input to the magnetic pole detection means. Therefore, the magnetic pole detection accuracy of the magnetic pole detection means can be ensured.

  A brushless motor according to a second aspect is the brushless motor according to the first aspect, wherein the magnetic flux guiding surface is chamfered at an edge of the circumferential surface.

  According to the brushless motor of the second aspect, the magnetic flux guiding surface is formed in a chamfered shape at the edge of the circumferential surface, so that the magnetic pole detecting means is surely directed. Thereby, many vertical components of the magnetic flux from the magnetic flux guide surface can be input to the magnetic pole detection means.

  A brushless motor according to a third aspect is the brushless motor according to the first aspect, wherein the magnetic flux guiding surface is formed in an arc shape at an edge of the circumferential surface.

  According to the brushless motor of the third aspect, the magnetic flux guiding surface is formed in an arc shape at the edge of the circumferential surface, so that the magnetic pole detecting means is surely directed. Thereby, many vertical components of the magnetic flux from the magnetic flux guide surface can be input to the magnetic pole detection means.

  A brushless motor according to a fourth aspect of the invention is the brushless motor according to the first aspect, wherein the magnetic flux guiding surface is formed in a polyhedral shape at an edge of the circumferential surface.

  According to the brushless motor of the fourth aspect, the magnetic flux guiding surface is formed in a multi-face shape on the edge of the circumferential surface, so that the magnetic pole detecting means is surely directed. Thereby, many vertical components of the magnetic flux from the magnetic flux guide surface can be input to the magnetic pole detection means.

  The brushless motor according to claim 5 is the brushless motor according to any one of claims 1 to 4, wherein the magnetic pole detection means is constituted by a Hall element surface-mounted on a circuit board. It is characterized by.

  According to the brushless motor of the fifth aspect, the magnetic pole detection means is constituted by a Hall element surface-mounted on the circuit board. Here, in general, Hall elements surface-mounted on a circuit board are specially mounted on lead-type Hall elements pin-mounted on a circuit board (for example, soldering separately from other surface-mount type elements). Step) is not required, and a holder for holding the circuit board is not necessary. Therefore, the magnetic pole detection means is constituted by the Hall element surface-mounted on the circuit board, so that the number of manufacturing steps can be reduced and the cost can be reduced as compared with the case of using the lead type Hall element pin-mounted on the circuit board. it can.

  In order to solve the above problem, a fluid pump device according to a sixth aspect includes the brushless motor according to any one of the first to fifth aspects.

  According to the fluid pump device of the sixth aspect, since the brushless motor according to any one of the first to fifth aspects is provided, the magnetic pole detecting means is axially and radially with respect to the magnet portion. Even if it is provided at a shifted position, a large amount of magnetic flux input to the magnetic pole detection means can be secured, so that the magnetic pole detection accuracy of the magnetic pole detection means can be secured.

  Hereinafter, the example which applied the brushless motor 10 of this invention to the fluid pump apparatus P1 is demonstrated.

  FIG. 1 is a side sectional view showing an overall configuration of a fluid pump device P1 to which a brushless motor 10 according to an embodiment of the present invention is applied. FIG. 2 is an enlarged view of a main part of FIG. FIG. 4 is a perspective view showing the overall configuration of the circuit board 32 provided in the fluid pump device P1 of FIG. 1. FIG. 4 shows a hall element 58 from the sensor magnet portion 54 of the rotor 30 provided in the fluid pump device P1 of FIG. Explanatory drawing explaining the flow of the magnetic flux to is shown, respectively.

  First, the configuration of a fluid pump device P1 to which the brushless motor 10 according to an embodiment of the present invention is applied will be described.

  The fluid pump device P1 to which the brushless motor 10 according to an embodiment of the present invention is applied is preferably used as an electric water pump for an engine cooling device of an automobile, for example, as shown in FIG. A pump unit 12 and a motor unit 14 arranged side by side in the axial direction are provided.

  The pump unit 12 includes a pump housing 16 configured in a substantially concave disk shape. The inside of the concave portion of the pump housing 16 is configured as a pump chamber 18. The pump housing 16 is provided with a suction port and a discharge port (not shown). Both the suction port and the discharge port are in communication with the pump chamber 18.

  An impeller 22 configured with a plurality of blades 20 is rotatably disposed in the pump chamber 18. The impeller 22 is formed integrally with a rotor 30 to be described later, and is configured to suck fluid from the suction port and to discharge the fluid in the pump chamber 18 from the discharge port to the outside as it rotates.

  The motor unit 14 includes the brushless motor 10 according to an embodiment of the present invention, and includes a stator 24, a pump body 26, a housing 28, a rotor 30, and a circuit board 32. Configured.

  The stator 24 is configured in an annular shape having a hole formed through in the axial direction, and integrally includes a core, a coil, and the like. The stator 24 is configured to generate a rotating magnetic field when supplied with a current from a circuit board 32 described later.

  The pump body 26 includes an inner cylinder portion 36 and an outer cylinder portion 38, and is assembled integrally with the pump housing 16 described above. In the pump body 26, a space between the inner cylinder portion 36 and the outer cylinder portion 38 is configured as an annular press-fit accommodation hole 40. The press-fit accommodation hole 40 has an opening on the housing 28 side and is formed along the axial direction. The above-described stator 24 is press-fitted and accommodated in the press-fitting accommodation hole 40. In addition, a support portion 42 is provided at the bottom of the inner cylinder portion 36 provided in the pump body 26, and a rotation shaft 44 disposed along the axial direction is supported on the support portion 42. .

  The housing 28 is disposed on one end side of the pump body 26 and is assembled integrally with the pump body 26. The housing 28 is provided with a substantially disk-shaped main body 46 that closes the opening of the outer cylinder portion 38 of the pump body 26. The housing 28 is provided with a connector 48 for electrically connecting a circuit board 32 and an external control device which will be described later.

  The rotor 30 is rotatably accommodated in an inner cylindrical portion 36 provided in the pump body 26, and is rotatably supported on the rotation shaft 44 via a bearing member 50. The entire rotor 30 is resin-molded with a plastic magnet (plastic magnet), and has a plurality of magnetic poles in the circumferential direction by preliminarily magnetizing the outer peripheral portion.

  Further, the rotor 30 is formed to have a longer axial length than the stator 24. A portion of the rotor 30 that is arranged to face the stator 24 in the radial direction is configured as a rotor magnet portion 52 that receives a rotating magnetic field from the stator 24 and generates a rotational force. Further, a portion of the rotor 30 that protrudes toward the housing 28 from the stator 24 is configured as a sensor magnet portion 54 (corresponding to a magnet portion) for detecting the rotational position.

  Moreover, the edge part by the side of the housing 28 in 54 A of outer peripheral surfaces (equivalent to the circumferential direction surface) of the sensor magnet part 54 is formed in the chamfering shape. And the part comprised by this chamfering shape is comprised as the magnetic flux guidance surface 56 for guiding a magnetic flux to the Hall element 58 mentioned later. The magnetic flux guiding surface 56 is a strongly magnetized surface and, as shown in FIG. 2, is configured to face the hall element 58 so that the hall element 58 described later is positioned on the normal line L. Yes.

  The circuit board 32 is disposed between the rotor 30 and the housing 28 described above. As shown in FIG. 3, the circuit board 32 has a surface mount type Hall element 58 (corresponding to a Hall IC or magnetic pole detection means) and other elements 60 such as a driver IC surface mounted. . The Hall element 58 is for detecting the position of the magnetic pole of the sensor magnet unit 54, and as shown in FIG. 2, the end surface of the sensor magnet unit 54 is radially outer than the outer peripheral surface 54A of the sensor magnet unit 54. It is disposed closer to the housing 28 than 54B.

  Next, the operation and effect of the fluid pump device P1 to which the brushless motor 10 according to one embodiment of the present invention is applied will be described.

  In the fluid pump device P1 according to the embodiment of the present invention, when a control signal is output from the external control device, the circuit board 32 generates a rotating magnetic field in the stator 24, and the rotor 30 is rotated by receiving the rotating magnetic field. The

  As described above, the rotor 30 is integrally provided with the sensor magnet portion 54 having a plurality of magnetic poles formed in the circumferential direction, and a magnetic flux guiding surface 56 is formed on the outer peripheral surface 54A of the sensor magnet portion 54. ing. As a result, during rotation of the rotor 30, the magnetic flux induced by the magnetic flux guiding surface 56 is input to the hall element 58 as indicated by the arrow W <b> 1 in FIG. 4.

  The magnetic flux induced by the magnetic flux guiding surface 56 is input to the Hall element 58, whereby the Hall element 58 detects the position of the magnetic pole of the sensor magnet unit 54 during the rotation of the rotor 30. Further, the circuit board 32 shown in FIG. 1 switches the timing of supplying current to the coil provided in the stator 24 based on the detection result of the Hall element 58 to generate a rotating magnetic field in the stator 24. As a result, the rotor 30 is rotated at a predetermined rotational speed, and the impeller 22 is rotated together with the rotor 30, whereby fluid is sucked into the pump chamber 18 from the outside via the suction port, and the fluid in the pump chamber 18 is discharged. It is discharged to the outside through the outlet.

  Here, as shown in FIG. 2, the Hall element 58 for detecting the position of the magnetic pole of the sensor magnet unit 54 is surface-mounted on the circuit board 32, so that the sensor magnet unit 54 has an axial direction and diameter. The magnetic flux guiding surface 56 for guiding the magnetic flux from the sensor magnet portion 54 to the Hall element 58 is provided on the outer peripheral surface 54A of the sensor magnet portion 54 so as to displace the Hall element 58. It is designed to be suitable.

  Therefore, as described above, even if the Hall element 58 is surface-mounted on the circuit board 32 and provided at a position shifted in the axial direction and the radial direction with respect to the sensor magnet portion 54, the outer peripheral surface of the sensor magnet portion 54. Many vertical components (see arrow W1 in FIG. 4) of the magnetic flux from the magnetic flux guiding surface 56 configured to face the Hall element 58 in 54A are input to the Hall element 58. Therefore, a large amount of magnetic flux input to the Hall element 58 is ensured, and the magnetic pole detection accuracy of the Hall element 58 can be ensured.

  Here, in order to clarify the operation and effect of the fluid pump device P1 according to the embodiment of the present invention, a comparison with the fluid pump device P2 according to the comparative example will be described.

  FIG. 11 is a side sectional view showing the overall configuration of a fluid pump device P2 according to a comparative example, FIG. 12 is an enlarged view of a main part of FIG. 11, and FIG. 13 is provided in the fluid pump device P2 of FIG. FIG. 14 is an explanatory diagram for explaining the flow of magnetic flux from the sensor magnet portion 154 of the rotor 130 provided in the fluid pump device P2 of FIG. 11 to the Hall element 158. Each is shown.

  In the fluid pump device P2 according to this comparative example, as shown in FIG. 12, the outer peripheral surface 154A of the sensor magnet portion 154 is configured so that the entire surface faces radially outward.

  In the fluid pump device P2 according to this comparative example, the hall element 158 is a lead type as shown in FIG. 13, and is mounted on the circuit board 132 by soldering or the like. Further, the Hall element 158 is fixedly held on the circuit board 132 by a holder 162 of a resin molded product, and as shown in FIG. 12, the sensor main body portion 158A faces the sensor magnet portion 154 in the radial direction. Has been placed.

  In the fluid pump device P2 according to this comparative example, as indicated by an arrow W2 in FIG. 14, the magnetic flux from the outer peripheral surface 154A that is the strongly magnetized surface of the sensor magnet unit 154 and faces radially outward is transferred to the Hall element 158. To be detected by.

  However, when the magnetic flux from the outer peripheral surface 154A facing the radially outer side in the sensor magnet portion 154 is detected by the Hall element 158 as described above, the sensor main body portion 158A of the Hall element 158 is connected to the sensor magnet portion 154 as described above. It is necessary to arrange them facing each other in the radial direction. For this reason, as shown in FIG. 13, it is necessary to use a lead type having a long lead 158B for the hall element 158.

  However, in general, this type of lead type hall element 158 is more expensive than the surface mount type hall element 58 (see FIG. 3). Further, the lead type hall element 158 needs to be mounted on the circuit board 132 in a mounting process different from the other surface mounting type element 160. For this reason, the manufacturing man-hour of the circuit board 132 increases.

  Further, when the lead type hall element 158 is used, the holder 162 for fixing and holding the circuit board 132 is required as described above. For this reason, not only the number of parts increases but the cost is increased, and an assembly process of the Hall element 158 and the holder 162 is also required, and the number of manufacturing steps of the circuit board 132 is further increased.

  On the other hand, according to the fluid pump device P1 according to the embodiment of the present invention, as shown in FIG. 2, the sensor magnet portion 54 is provided with a chamfered magnetic flux guiding surface 56 on the outer peripheral surface 54A. Therefore, it is not necessary to arrange the Hall element 58 so as to face the sensor magnet portion 54 in the radial direction. For this reason, a surface mount type element can be used for the Hall element 58 and surface mount can be performed on the circuit board 32.

  Then, by using a surface mount type of the Hall element 58, the Hall element 58 can be mounted on the circuit board 32 in the same mounting process as the other surface mount type elements 60, so that a special mounting process ( For example, another surface mounting type element 60 and a separate soldering step) are not required, and a holder 162 (see FIG. 13) for fixing and holding the circuit board 32 is not required. Therefore, by using a surface mount type Hall element 58, the number of manufacturing steps can be reduced and the cost can be reduced as compared with the case of using a lead type Hall element 158 (see FIG. 13) pin-mounted on the circuit board 32. Can go down.

  Further, according to the fluid pump device P1 according to the embodiment of the present invention, as described above, the Hall element 58 is surface-mounted on the circuit board 32, so that the sensor magnet portion 54 is displaced in the axial direction and the radial direction. Even if it is provided at the position, the vertical element (see arrow W1 in FIG. 4) of the magnetic flux from the magnetic flux guiding surface 56 configured to face the hall element 58 on the outer peripheral surface 54A of the sensor magnet portion 54 58 can be entered. As a result, a large amount of magnetic flux input to the Hall element 58 can be secured, and therefore the magnetic pole detection accuracy of the Hall element 58 can be secured.

  Further, according to the fluid pump device P1 according to the embodiment of the present invention, the magnetic flux guide surface 56 is formed in a chamfered shape at the edge of the outer peripheral surface 54A, so that the Hall element 58 is surely faced. Yes. Thereby, many vertical components of the magnetic flux from the magnetic flux guiding surface 56 can be input to the Hall element 58.

  Next, a modification of the fluid pump device P1 to which the brushless motor 10 according to one embodiment of the present invention is applied will be described.

  In the above embodiment, the magnetic flux guiding surface 56 is formed in a chamfered shape at the edge of the outer peripheral surface 54A of the sensor magnet portion 54 on the housing 28 side, but may be formed as follows.

  That is, for example, as shown in FIG. 5, the magnetic flux guide surface 56 may be formed in an arc shape (concave curved shape) on the edge portion on the housing 28 side of the outer peripheral surface 54 </ b> A of the sensor magnet portion 54. Further, for example, as shown in FIG. 6, the magnetic flux guiding surface 56 may be formed in a multifaceted shape on the edge of the outer peripheral surface 54 </ b> A of the sensor magnet portion 54 on the housing 28 side.

  As described above, even if the magnetic flux guiding surface 56 is formed in an arc shape or a multi-face shape on the edge of the outer peripheral surface 54A, the magnetic flux guiding surface 56 can be reliably directed to the Hall element 58. Many vertical components of the magnetic flux can be input to the Hall element 58.

  In the above-described embodiment, the Hall element 58 is disposed on the radially outer side with respect to the outer peripheral surface 54A of the sensor magnet portion 54, and the outer peripheral surface 54A of the sensor magnet portion 54 is directed so that the magnetic flux guiding surface 56 faces the Hall element 58. However, it may be configured as follows.

  That is, for example, as shown in FIG. 7, the Hall element 58 is arranged on the radially inner side with respect to the inner peripheral surface 54 </ b> C of the sensor magnet portion 54, and the sensor magnet so that the magnetic flux guiding surface 56 faces the Hall element 58. It may be provided on the inner peripheral surface 54 </ b> C of the portion 54.

  Further, in the above embodiment, in the inner rotor type brushless motor 10 in which the rotor 30 is disposed on the radially inner side of the stator 24, the Hall element 58 is disposed on the radially outer side with respect to the outer peripheral surface 54A of the sensor magnet portion 54, Although the magnetic flux guiding surface 56 is provided on the outer peripheral surface 54A of the sensor magnet portion 54, it may be configured as follows.

  That is, for example, as shown in FIG. 8, the brushless motor 10 is an outer rotor type in which the rotor 30 is disposed on the radially outer side of the stator 24, and the Hall element 58 is in the radial direction with respect to the outer circumferential surface 54 </ b> A of the sensor magnet unit 54. The magnetic flux guide surface 56 may be provided on the outer peripheral surface 54 </ b> A of the sensor magnet unit 54.

  For example, as shown in FIG. 9, the brushless motor 10 is an outer rotor type in which the rotor 30 is disposed on the radially outer side of the stator 24, and the Hall element 58 has a diameter relative to the inner peripheral surface 54 </ b> C of the sensor magnet unit 54. The magnetic flux guide surface 56 may be provided on the inner peripheral surface 54 </ b> C of the sensor magnet unit 54.

  In the above embodiment, the entire rotor 30 is resin-molded by a plastic magnet (plastic magnet), and the sensor magnet unit 54 is configured integrally with the rotor magnet unit 52. However, the following configuration may be used.

  That is, for example, as illustrated in FIG. 10, the rotor magnet unit 52 and the sensor magnet unit 54 may be configured separately from each other after being separated from each other.

  In the above embodiment, the Hall element 58 is used to detect the position of the magnetic pole of the sensor magnet unit 54. However, the position of the magnetic pole of the sensor magnet unit 54 is detected by other elements. May be.

It is side surface sectional drawing which shows the whole structure of the fluid pump apparatus with which the brushless motor which concerns on one Embodiment of this invention was applied. It is a principal part enlarged view of FIG. It is a perspective view which shows the whole structure of the circuit board provided in the fluid pump apparatus of FIG. It is explanatory drawing explaining the flow of the magnetic flux from the sensor magnet part of the rotor provided in the fluid pump apparatus of FIG. 1 to a Hall element. It is a figure which shows the modification of the magnetic flux guidance surface which concerns on one Embodiment of this invention. It is a figure which shows the modification of the magnetic flux guidance surface which concerns on one Embodiment of this invention. It is a figure which shows the modification of the brushless motor which concerns on one Embodiment of this invention. It is a figure which shows the modification of the brushless motor which concerns on one Embodiment of this invention. It is a figure which shows the modification of the brushless motor which concerns on one Embodiment of this invention. It is a figure which shows the modification of the brushless motor which concerns on one Embodiment of this invention. It is side surface sectional drawing which shows the whole structure of the fluid pump apparatus which concerns on a comparative example. It is a principal part enlarged view of FIG. It is a perspective view which shows the whole structure of the circuit board provided in the fluid pump apparatus of FIG. It is explanatory drawing explaining the flow of the magnetic flux from the sensor magnet part of the rotor provided in the fluid pump apparatus of FIG. 11 to a Hall element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Brushless motor, 12 ... Pump part, 14 ... Motor part, 16 ... Pump housing, 18 ... Pump chamber, 20 ... Blade, 22 ... Impeller, 24 ... Stator, 26 ... Pump body, 28 ... Housing, 30 ... Rotor, 32 ... Circuit board, 36 ... Inner cylinder part, 38 ... Outer cylinder part, 40 ... Press-fit accommodation hole, 42 ... Support part, 44 ... Rotating shaft, 46 ... Main part, 48 ... Connector, 50 ... Bearing member, 52 ... Rotor 54A ... Outer surface (circumferential surface), 54B ... End surface, 54C ... Inner peripheral surface (circumferential surface), 56 ... Magnetic flux induction surface, 58 ... Hall element (magnetic pole) Detection means), 60... Other elements

Claims (6)

A stator that generates a rotating magnetic field;
A rotor that is arranged to face the stator in the radial direction and is rotated by receiving a rotating magnetic field from the stator;
A magnet portion provided integrally with the rotor and formed with a plurality of magnetic poles in the circumferential direction;
A magnetic pole detection means for detecting the position of the magnetic pole of the magnet unit, provided at a position shifted in the axial direction and the radial direction with respect to the magnet unit;
A magnetic flux guiding surface provided on a circumferential surface of the magnet portion and facing the magnetic pole detection means;
A brushless motor characterized by comprising:   The brushless motor according to claim 1, wherein the magnetic flux guiding surface is formed in a chamfered shape at an edge of the circumferential surface.   The brushless motor according to claim 1, wherein the magnetic flux guide surface is formed in an arc shape at an edge of the circumferential surface.   The brushless motor according to claim 1, wherein the magnetic flux guide surface is formed in a multi-face shape at an edge of the circumferential surface.   The brushless motor according to any one of claims 1 to 4, wherein the magnetic pole detecting means is configured by a Hall element surface-mounted on a circuit board.   A fluid pump device comprising the brushless motor according to any one of claims 1 to 5.

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