JP2003333818A - Brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brushless motor which can shorten an overall length and also can facilitate the arrangement of a Hall element and the adjustment of an arrangement position. <P>SOLUTION: In this brushless motor which is equipped with a field coil around the rotor magnet of an inner rotor having a rotary shaft and also is equipped with a Hall element for detecting a magnetic field at the rotation of the rotor magnet, one end of the rotor magnet is formed with a small- diameter part which is made by making the diameter of an end smaller than that of the other section of the rotor magnet, and a Hall element storage is arranged between the inside periphery of a field coil and the outside periphery of the small-diameter part of the rotor magnet. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inner rotor magnet type brushless motor.

[0002]

2. Description of the Related Art Conventionally, as a small motor, an inner rotor magnet type brushless motor has been generally known as well as a coreless motor. The structure of the brushless motor will be described below with reference to the drawings.

The brushless motor 300 includes, as shown in FIG. 3, an inner rotor portion 302, a field coil 301,
A Hall element 303, a Hall sensor substrate 304, a housing case 305, etc. are provided. Note that FIG. 3 illustrates a side cross section of the brushless motor 300.

The inner rotor portion 302 comprises a substantially cylindrical rotor magnet 321, a rotating shaft 322 fixed through the center of the rotor magnet 321, and a magnet yoke 325. The rotary shaft 322 is rotatably supported by bearings 362 and 372 at the axial center positions of the flange 306 and the end flange 307 located at both openings of the substantially cylindrical housing case 305.

The field coil 301 is arranged around the inner rotor portion 302 and is fixed to the inner peripheral surface of the housing case 305 via laminated steel plates 351 arranged in the axial direction.
Further, in the case of a three-phase coil, for example, the field coil 301 is an inner rotor unit 302 under the control of the drive circuit based on the detection result of the Hall element 303 including the other two 120 ° equidistant positions (not shown). A rotating magnetic field is generated to drive the rotation.

Hall sensor substrates 304 are respectively connected to three hall elements 303 for detecting changes in the magnetic field during rotation of the rotor magnet 321, and the changes in the magnetic field detected by the hall elements 303 at these respective locations. Is output as a signal to the drive circuit side (not shown). The drive circuit is
Based on the Hall element output signal, the inner rotor section
In order to drive 302 to rotate, the timing of supplying a current from a drive circuit (not shown) to the field coil 301 is controlled.

Brushless motor 30 configured as described above
0 is to generate a rotating magnetic field in the field coil 301 by controlling the supply timing of the current from the drive circuit to the field coil 301 based on the detection result of each Hall element 303.
The rotating magnetic field causes the inner rotor portion 302 to rotate and gives a rotating torque to the rotating shaft 322.

[0008]

By the way, in order for the rotating magnetic field generated in the field coil to be efficiently supplied to the rotation of the inner rotor portion, the field coil and the rotor magnet are placed as close as possible, or It is necessary to increase the effective range facing each other. At the same time, since the Hall element needs to accurately detect the magnetic field of the rotor magnet, it is desired to bring the Hall element and the rotor magnet close to each other.

Therefore, as shown in FIG.
1 is provided as close as possible to the rotor magnet 321, and the rear end of the field coil 301 is positioned closer to the front side than the rear end face of the rotor magnet 321.
A space D for disposing the Hall element 303 is provided outside the rotor magnet 321 behind the rear end of the 301.
The hall element 303 is arranged in the space D.

However, in the above structure, the Hall element
Only in order to detect the magnetic field of the rotor magnet 321 with 303, the total length of the rotor magnet 321 is made longer than the total length of the field coil 301, so that the A dimension portion shown in FIG. It was necessary, and there was a problem that the total length of the motor became long.

Further, the brushless motor 3 of the hall element 303
After mounting the end flange 307 so as to close the rear end portion of the housing case 305, the Hall element 303 connected to the Hall sensor substrate 304 is inserted into the slit 371 of the end flange 307. Had to do. Further, in order to accurately detect the magnetic field of the rotor magnet 321 by the hall element 303, it is also necessary to finely adjust the arrangement position of the hall element 303 by rotating the hall sensor substrate 304 itself within the range of the slit 371. there were. In particular, when these operations are performed on a small brushless motor, it is troublesome and complicated.

In addition, in such a configuration, the Hall element
Hall sensor board 304 to which 303 is connected is end flange
It will be provided on the rear end surface of 307. Therefore, since it is necessary to provide the cover 353 member on the rear side of the end flange 307 so as to cover the exposed Hall sensor substrate 304 from the rear side, as shown in the B dimension portion shown in FIG. 2B, Brushless motor 300 by this cover 353 member
Had become even longer.

SUMMARY OF THE INVENTION An object of the present invention is to provide a brushless motor which can shorten the total length of the motor and facilitate the arrangement of Hall elements and the adjustment of the arrangement position.

[0014]

According to a first aspect of the invention, a stator side field coil is provided around a rotor magnet of an inner rotor having a rotating shaft, and a hall element for detecting a magnetic field of the rotor magnet. In the brushless motor, the one end of the rotor magnet is provided with a small-diameter portion in which the diameter of the end is smaller than the other portion of the rotor magnet.
A hall element is arranged between the field coil and the small diameter portion of the rotor magnet.

According to the first aspect of the present invention, one end portion of the rotor magnet is provided with a step which is a small diameter portion in which the diameter of this end portion is smaller than that of the other portion of the rotor magnet. Between the rotor-side small-diameter portion and the stator-side field coil, there is provided a space in which the minimum necessary Hall element is arranged, and the Hall element is arranged in that space. As a result, it is not necessary to extend the entire length of the rotor magnet by the amount of the Hall element as in the conventional example.

Further, in rotating the rotor magnet based on the rotating magnetic field generated in the field coil, it is desired to dispose the rotor magnet and the field coil as close to each other as possible. Since the end portion of the magnetic coil has a low contribution rate to the motor torque of the brushless motor, the motor torque is hardly weakened even when the brushless motor is configured as described above.

Further, in the invention described in claim 2, in claim 1,
In the brushless motor described, the Hall element,
It is characterized in that the rotor magnet is arranged in the small-diameter end portion and within the inner diameter range along the axial direction of the rotating shaft of the field coil.

According to the invention of claim 2, it is possible to obtain the same effect as that of the invention of claim 1.

According to a third aspect of the present invention, in the brushless motor of the first or second aspect of the present invention, a cylindrical housing case having both ends opened is provided, and the brushless motor is fixed to both ends of the housing case. And a flange and an end flange of a lid body that rotatably supports the rotation shaft of the inner rotor arranged in the housing case, and the end flange side of the end portion of the rotor magnet that is a small diameter portion. A hall sensor substrate connected to the hall element and supporting the hall element is fixed to an inner surface facing the hall element.

According to the third aspect of the present invention, since the hall sensor substrate is fixed to the inner surface of the end flange of the rotor magnet on the side of the small diameter which faces the hall element, the hall sensor substrate is fixed. There is no need to provide a cover member for covering the Hall sensor substrate in the exposed state as in the case where the brush is provided on the outside of the end flange, and the total length of the brushless motor can be shortened including the thickness of the cover member.

Further, since the Hall sensor substrate is connected to the Hall element and supports the Hall element, at least a part of the end flange is inserted into the opening at the end of the housing case, and the housing case can be rotationally adjusted. The Hall element is correctly disposed in the brushless motor by being finally fixed from.

According to a fourth aspect of the invention, in the brushless motor according to the third aspect, the end flange to which the Hall sensor substrate is fixed is inserted into one end of the opening of the housing case, and the positioning is fixed to the housing case. It is characterized in that the rotation can be adjusted around the rotation axis before the above.

According to the fourth aspect of the present invention, the Hall element is incorporated into the Hall sensor substrate and fixed, and after the end flange is inserted into one end of the opening of the housing case and before being fixed to the housing case side, The end flange itself of the lid body is rotationally moved around the rotation axis, and each Hall element is rotationally adjusted by the rotational movement, so that the arrangement position of the Hall element in the brushless motor can be changed.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Specific embodiments of the present invention will be described below with reference to the drawings. However, the scope of the invention is not limited to the illustrated example.

FIG. 1 is a side sectional view showing an essential part of a brushless motor, and FIGS. 2 (a) and 2 (b) are comparisons between the brushless motor shown in FIG. 1 and the conventional brushless motor shown in FIG. FIG. In FIG. 2, for simplification, only a half portion from the center line of the side cross section of each brushless motor is shown.

The brushless motor 100 is a small inner rotor magnet type brushless motor similar to the above, and as shown in FIG. 1, for example, a rotating magnetic field is generated by a current supplied from a drive circuit (not shown) of a power source. The field coil 1 on the stator side, the inner rotor portion 2 that rotates based on the rotating magnetic field, the Hall element 3 for detecting a change in the magnetic field during rotation of the rotor magnet 21, and the Hall element 3 are detected. The output signal is the change in the magnetic field,
Hall sensor substrate 4 connected to a drive circuit (not shown) that controls the timing of current supply to field coil 1, housing case 5 that houses these components, and a flange that closes both openings of housing case 5. 6 and an end flange 7 have a schematic structure.

Of these, the housing case 5 is a substantially cylindrical (cylindrical) member made of, for example, a non-magnetic material. The inner peripheral surface of the housing case 5 has, for example, a thickness laminated in the axial direction in order to prevent an eddy current from flowing.
An annular laminated steel plate 51 of about 0.5 mm is provided.

On the inner peripheral surface side of the laminated steel plate 51, for example, a cylindrical field coil 1 extending in the axial direction is provided as a stator portion. The field coil 1 varies depending on the type of brushless motor, but in the present embodiment, a hexagonal wound sheet coil using a hexagonal winding frame in the winding step is shown as the field coil 1 formed into a cylindrical shape. There is.
Further, the inner rotor portion 2 is provided inside the cylindrical field coil 1.
Is provided.

The inner rotor portion 2 is made of, for example, a high-performance rare earth permanent magnet, and has a substantially cylindrical rotor magnet 21 extending in the same direction as the field coil 1 so as to be close to the field coil 1, and this rotor. The magnet 21 includes a rotating shaft 22 fixed through substantially the center of the magnet 21 and a magnet yoke 25 serving as a back yoke.

The rotor magnet 21 is provided so that the rear end face of the end flange 7 side thereof and the rear end face of the field coil 1 are substantially aligned, and the axial length of the rotor magnet 21 is the same as that of the field coil 1. It is equal to or slightly less than the axial length. Further, the rotor magnet 21 has a rear end portion (end portion on the end flange side).
On the side of the field coil 1 in the circumferential direction of 211, for example, a small diameter portion 23 which is a stepped portion cut out in a ring shape over the entire circumference is provided. That is, the diameter of the step portion is smaller than that of the other outer peripheral portion of the rotor magnet 21.

The small-diameter portion 23 has, for example, a dimensional length in the axial direction that is slightly longer than the axial length of the Hall element 3. In addition, the clearance between the inner and outer diameters from the outer peripheral surface of the small diameter portion 23 to the inner surface of the field coil 1 is larger than the thickness of the Hall element 3.

In this way, in the space between the small diameter portion 23 of the step portion and the field coil 1, for example, the Hall element housing portion E in which the Hall element 3 is housed is formed. The Hall element 3 is housed in the Hall element housing portion E, so that the Hall element 3 is arranged within a range along the axial direction of the rotating shaft 22 of the field coil 1.

On the other hand, the rotary shaft 22 is located coaxially with the housing case 5, and
Bearings 62 and 72 are rotatably supported by bearings 62 and 72 on both sides of the flange 6 and the end flange 7 provided at both openings of the valve 5.

The flange 6 is, for example, a housing case 5
The rotary shaft 22 is provided with a fixing portion 61 which is fixed in a state of covering the output side opening portion thereof, and the fixing portion 61 is press-fitted into the opening portion of the housing case 5.
It is fitted and fixed to. The outer diameter of the fixed portion 61 is slightly larger than the inner diameter of the end portion of the housing case 5.

Further, the flange 6 is provided with a recess in the brushless motor 100 substantially at the center thereof, and a bearing 62 for pivotally supporting the rotary shaft 22 is fitted in the recess. And, through this bearing 62, the rotating shaft
22 penetrates substantially the center of the flange 6. The flange 6
Although not shown, a gear or the like that rotates together with the rotating shaft 22 to be driven is attached to the outer side (on the output side of the left rotating shaft in FIG. 1).

On the other hand, the end flange 7 is provided with a fixing portion 71 for fixing the housing case 5 in a state of covering the opening on the opposite output side (the end portion side of the rotor magnet which is the small diameter portion). By fitting and inserting the fixing portion 71 into the opening of the housing case 5 shown in the figure, the Hall element 3 is rotationally adjusted and then positioned, and fixed to the housing case 5 by caulking. The outer diameter of the fixed portion 71 is substantially equal to or slightly smaller than the inner diameter of the end portion of the housing case 5 opposite to the output side. The fixing method is not limited to the crimp fixing.

The end flange 7 is provided with a recess at substantially the center inside the brushless motor 100, and a bearing 72 for receiving the rotary shaft 22 is fitted in the recess. The rotary shaft 22 is located approximately at the center of the end flange 7 via the bearing 72.

The end flange 7 is provided with the Hall sensor substrate 4 on its inner end surface (inner surface facing the Hall element) 73. In case of three-phase coil, this Hall sensor board
4, in the same position as the recess 41 formed in the end flange 7,
The Hall elements 3 are mounted at 120 ° even distribution. Each hall element 3 is specifically, the hall element housing portion E
Are provided at circumferential positions substantially equal to the central position in the radial direction.

Although not shown, the end flange 7 is provided with a through hole for passing a plurality of lead wires, one end of which is connected to a drive circuit, for supplying a current to the field coil 1. There is.

Next, the brushless motor 100 of the Hall element 3
The arrangement and the adjustment method of the arrangement position will be described.

First, the laminated steel plates 51 and the field coil 1 are arranged and fixed on the inner peripheral surface of the housing case 5, and the flange 6 is press-fitted into the opening on the output side (left side in the figure) of the rotary shaft 22 of the housing case 5. The inner rotor portion 2 is fixed and inserted into the housing case 5 so that the rotation shaft 22 of the inner rotor portion 2 penetrates the bearing 62 at the center of the flange 6.

On the other hand, in the case of a three-phase coil, the end surface 73 of the end flange 7 on the inner side of the brushless motor 100 is 120 °.
The Hall sensor substrate (4) having the Hall elements (3) arranged and fixed thereto is fixed at equal distribution positions. Then, the end flange 7 provided with the hall element 3 and the hall sensor substrate 4 is arranged so that the hall element 3 is housed in the hall element housing portion E, and the rotary shaft 22 has a bearing 7 centered on the end flange 7.
It is inserted into the opening of the housing case 5 so as to be inserted into 2.

Then, the entire end flange 7 is attached to the rotary shaft 22.
By rotating the Hall element 3 by rotating it around the center, the Hall element 3 is rotationally adjusted, and the angle of the end flange 7 is specified so that the Hall element 3 has the most suitable arrangement in the positional relationship with the field coil 1. Then, the end flange 7 is caulked and fixed to the housing case 5 side at the specified position. In this way, the arrangement position of the Hall element 3 is finely adjusted and determined.

As a result, the Hall element 3 is correctly placed inside the brushless motor 100.

The flange 6 and the end flange 7 are
For example, the fixing portions 61 and 71 are attached by inserting the fixing portions 61 and 71 into the ends of the openings of the housing case 5, and the fixing portion 61 side of each opening portion is press-fitted and the fixing portion 71 side is fixed. The inserted portion is firmly fixed by crimping it from the outer periphery of the housing case 5, but it is not limited to this. The shape of the housing case may be one in which the flange 6 side is omitted by deep drawing, and a deformed housing case can also be applied.

As described above, according to the brushless motor 100 of the above-described embodiment, each hall is accommodated in the hall element housing portion E provided between the small diameter portion 23 of the step of the rotor magnet 21 and the field coil 1. By arranging the element 3, the entire length of the rotor magnet 21 is reduced by the amount of the hall element 3 as in the conventional case.
There is no need to increase the total length.

Further, since the Hall sensor substrate 4 is provided on the end surface 73 inside the end flange 7, the cover 353 member for covering the Hall sensor substrate 4 as in the conventional case, substantially as shown in FIG. It is not necessary to provide a space for the B dimension shown, and the total length of the brushless motor 100 can be shortened by the thickness of the cover member. Therefore, the total length of the brushless motor 100 can be shortened by the length of the C dimension portion shown in FIG. 2A in comparison with the dimension A of FIG. 2B as compared with the conventional brushless motor.

Further, when the brushless motor 100 is configured as described above and the hall element 3 is arranged in the hall element housing portion E which is a space between the small diameter portion 23 of the step portion and the field coil 1,
Since the end portion of the field coil 1 has a low contribution to the motor torque of the brushless motor 100, the motor torque is hardly weakened.

The hall sensor substrate 4 connected to the hall element 3 and supporting the hall element 3 is integrally provided on the inner end surface 73 of the end flange 7, and the end flange 7 has its fixing portion 71 at the housing case 5. The hole element 3 is inserted into the opening end of the housing case 5 and is provided in the housing case 5 in such a manner that it can be rotationally adjusted. It can be provided.

The present invention is not limited to the above embodiment. For example, although the rear end portion 211 of the rotor magnet 21 is cut out in a ring shape to make a step to form the small diameter portion 23, the present invention is not limited to this.
Rotate the end of the rotor magnet 21 in the radial direction.
The shape is arbitrary as long as there is a space in which the Hall element housing portion E smaller than the other portions of 21 can be secured.

Further, in the above embodiment, one end of the rotor magnet 21 and one end of the field coil 1 are provided so as to be substantially aligned with each other.
It suffices that the end surface of the rotor magnet 21 is located inside the cylinder at a position shorter than the end surface of the field coil 1 as long as the end surface of the rotor magnet 21 is located within an effective range along the axial direction of the rotating shaft 22. good.

Further, in the above embodiment, the timing of supplying the current from the drive circuit to the field coil 1 is controlled based on the signal output from the Hall element 3 via the Hall sensor substrate 4. However, the present invention is not limited to this, and for example, a drive circuit may be mounted on the Hall sensor substrate 4 to control the timing of supplying the current to the field coil 1.

[0053]

As described above, according to the first aspect of the present invention, a small diameter portion having a step is formed around one end of the rotor magnet so that the diameter of this end is smaller than that of the other portion of the rotor magnet. Therefore, a space for arranging each Hall element is provided between the outer circumference of the small-diameter portion of the rotor magnet of the rotating portion and the inner diameter of the stator cylindrical field coil, and the Hall element can be arranged in the space. it can. Therefore, it is not necessary to lengthen the total length of the rotor magnet by the space for arranging the Hall element as in the past, and at the same time, the positional relationship between the field coil and the rotor magnet can be arranged close to each other. Can be shortened.

Further, since the end portion of the field coil has a low contribution to the motor torque of the brushless motor, even if the brushless motor is configured as described above, the motor torque is hardly weakened due to the characteristics of the motor.

According to the invention described in claim 2, it is possible to obtain the same effect as that of the invention described in claim 1.

According to the third aspect of the invention, the Hall sensor substrate is fixed to the inner surface of the end flange of the rotor magnet on the side of the small diameter which faces the Hall element. It is not necessary to provide a cover member for covering the Hall sensor substrate, and the total length of the brushless motor can be shortened by the thickness of the cover member.

The Hall sensor substrate is connected to the Hall element, supports the Hall element, and is fixed to the end flange. At least a part of the end flange is fitted into the opening at the end of the housing case and is provided in a state in which it can be rotationally adjusted with respect to the housing case. Each Hall element can be arranged accurately and easily.

According to the invention described in claim 4, the Hall element is assembled and fixed in the Hall sensor substrate, and after the end flange is inserted into one end of the opening of the housing case, before being fixed to the housing case side, The end flange itself of the lid body is rotationally moved around the rotation axis, and each Hall element is rotationally adjusted by the rotational movement, so that the arrangement position of the Hall element in the brushless motor can be changed.

[Brief description of drawings]

FIG. 1 is a side sectional view of a brushless motor illustrated as an embodiment of the present invention.

FIG. 2 is a schematic side sectional view showing a comparison between the brushless motor of the present invention and a conventional brushless motor.

FIG. 3 is a side sectional view showing a conventional brushless motor.

[Explanation of symbols]

100, 300 brushless motor 1,301 field coil 2,302 Inner rotor part 21,321 Rotor magnet 211 Edge 22,322 rotary shaft 23 Small diameter part 25, 325 Magnet yoke 3, 303 Hall element 4, 304 Hall sensor board 5,305 housing case 51, 351 laminated steel plate 6,306 flange 61, 71 Fixed part 62, 72, 362, 372 bearings 7,307 End flange 73 Edge E storage

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5H019 AA08 AA10 BB01 BB05 BB15                       BB20 BB22 CC03 EE14 FF01                 5H605 AA08 BB05 BB10 CC08 DD05                       EC20 GG03

Claims (4)

[Claims] 1. A brushless motor comprising a stator side field coil around a rotor magnet of an inner rotor having a rotating shaft and a Hall element for detecting a magnetic field of the rotor magnet. A small diameter portion having a diameter of this end smaller than that of the other portion of the rotor magnet is provided at one end portion of the rotor magnet, and a Hall element is arranged between the field coil and the small diameter portion of the rotor magnet. Brushless motor characterized by having 2. The hall element is arranged in an end portion which is a small diameter portion of the rotor magnet and in an inner diameter range of the field coil along an axial direction of the rotating shaft. The brushless motor according to claim 1. 3. A cylindrical housing case having both ends open, which is fixed to each of both ends of the housing case and is rotatable about a rotation shaft of the inner rotor arranged in the housing case. A flange and an end flange of a supporting lid are provided, and the inner surface of the end flange on the end side, which is the small diameter portion of the rotor magnet, facing the hall element is connected to the hall element and supports the hall element. The brushless motor according to claim 1 or 2, wherein the Hall sensor substrate is fixed. 4. The end flange to which the Hall sensor substrate is fixed is inserted into an end of the opening of the housing case, and is rotationally adjustable about the rotation axis before being positioned and fixed to the housing case. The brushless motor according to claim 3, wherein: