JPS5926785Y2 - Assembly structure of motor position detection part - Google Patents

Description

[Detailed description of the invention] This invention detects the rotational position (rotation angle) of the rotor magnet, and controls the energization button and current direction to the stator coil according to this detection output. This invention relates to an assembly structure of a detection unit.

Hereinafter, prior to explaining the present invention, the operation of the position detection section of the brushless motor will be explained with reference to the drawings.

FIG. 1A is a schematic plan view for explaining an energization control operation by a position detection section of a brushless motor composed of a three-phase stator coil 1 and a two-pole rotor magnet 2. FIG.

In FIG. 1A, the first phase coil 1a is formed by the coil pieces a and a' perpendicular to the plane of the paper, and the coil pieces are formed in the same manner thereafter.

A second phase coil 1b is formed by b', and a third phase coil 1c is formed by coil pieces c and c'.

These first, second, and third phase coils 1 a plb,
lc are arranged with a mechanical angle difference of 120° on the horizontal plane.If the angle in the direction from the central axis R perpendicular to the plane of the paper toward the coil piece a is 0°, the coil piece a is 120°. , the coil piece C is placed at an angle of 2400 degrees.

The rotor magnet 2 is magnetized in the thickness direction.
The magnet 2N has a north pole on the inside (the side facing the stator coil 1), and the magnet 2S has a south pole on the inside.
It has a cylindrical shape.

The junctions t and t' of these magnets 2N and 2S are at an angle of 180 degrees to each other.

With this configuration, a current k flows perpendicularly to the plane of the paper from the back to the front of the coil piece located in the range of the N-pole magnet 2N, and a current k flows from the front to the back of the paper to the coil piece located within the range of the S-pole magnet 2S. When current is applied to each rotor magnet 2, rotational torque is applied to the rotor magnet 2 in a counterclockwise direction, that is, in the direction of arrow X in the figure.

When the rotor magnet 2 rotates due to this rotational torque, the magnetic field applied to the coil pieces also changes, so the current direction of the coil pieces is controlled according to the rotation position or rotation angle of the rotor magnet 20, so that the current direction in the coil pieces is always controlled. Control is performed so that rotational torque in the direction of arrow X is obtained.

This can be done, for example, by a position detection section using a magnetically sensitive element such as a Hall element fixedly disposed at a position facing the end surface of the rotor magnet 2 as a position detection element.

By the way, the joint part t of the rotor magnet 2 is as shown in FIG.
From the position where the angle is 0°, it rotates once in the direction of arrow
The strength of the magnetic field applied to the coil piece a is as shown by the thick solid line in FIG. 1B.

Further, the strength of the magnetic field applied to the coil piece a' at the angle of 180° is as indicated by the broken line in FIG. 1B.

As is clear from these FIGS. 1A and 1B, the joint portion t.

In the vicinity of the rotation angle O0, 180°, 36C)' where t' is located near the coil pieces a and a', the strength of the magnetic field is close to zero, so during this time the coil piece a.

Even if a' is energized, the generated torque is small and the efficiency is poor.

So in reality, for example, the angle cf, 1s o
o, 3600 (7) Without carrying out energization within ±30 degrees, we carried out so-called 1200 energization in the areas from 30 degrees to 150 degrees, the button and from 210 degrees to 3300 degrees, as shown by the diagonal lines in Figure 1B. ing.

In order to perform such 120° energization, the joint t of the rotor magnet 2 must be at an angle of 3 with respect to the coil piece a.
It is necessary to fully detect the rotation by 0° in the direction of the arrow X, and it is necessary to arrange the Hall element 3ak at a position 30 degrees apart from this angle and detect the point of change from the south pole to the north pole.

Similarly, it is necessary to arrange the Hall element 3bk at a position 301 away from the coil piece, and the Hall element 3cffi at a position 30° ahead from the coil piece C.

Since these Hall elements 3a, 3b, and 3c can be distinguished as S poles and N poles, the energization start positions at the S and N poles (positions at angles 300i- and 2100 in FIG. 1B)
can be detected.

The energization stop position may be detected by further arranging three Hall elements at each position, or the energization may be stopped using the energization start position detection signal of the next phase.

Furthermore, the three Hall elements 3a, 3b, and 3c can distinguish between S and N poles, and for example, generate a positive output when an S pole is detected, and a negative output when an N pole is detected. , the current direction of each coil is determined according to the positive/negative of this.The Hall element 3c is moved by a gold magnetic angle of 180 degrees and placed at the position of the Hall element 3c' in FIG. As for 30', by reversing the polarity of the S and N pole detection outputs, it is possible to perform the same operation as the Hall element 3c.

However, the Hall element 3a for the stator coil 1,
If the mounting positions of 3b and 3c are incorrect, normal 1200 energization as described above cannot be performed.

That is, for example, as shown in FIG. 2A, when the Hall element 3a is placed at a position advanced by an angle X0 (~30°) with respect to the coil piece a, as shown in FIG. 2B,
Electricity begins to flow at angle X0, and efficiency decreases.

Therefore, it is necessary to accurately determine the arrangement angles of the Hall elements 3a, 3b, 3c with respect to each coil piece a, b, c.

In addition, as shown in Fig. 3, when the Hall element is disposed facing the end surface of the cylindrical rotor magnet 2 magnetized in the thickness direction (radial direction), The strength of the magnetic field changes depending on the position (in the direction of arrow Y), and in an extreme example, the detected magnetic poles may be reversed, as in the case of Hall elements 3a and 3a' in FIG.

Therefore, in the above case, it is also necessary to accurately determine the radial position.

For this reason, in conventional motors, it is necessary to locate a so-called neutral point, in which a position detection element such as the Hall element 3 is placed at a fixed position relative to the stator coil 1. After finding the position, the position detecting element is fixed with screws or adhesive to assemble the position detecting section.

Therefore, the assembly work is troublesome, the precision of the fixing position is low, and it is difficult to obtain a highly efficient motor 4.

The present invention has been made in view of the above-mentioned circumstances, and is capable of fixing a position detection element such as a Hall element 3, which detects the rotational position of the rotor magnet 2, at a fixed position with respect to the stator coil 1 with high precision. It is an object of the present invention to provide an assembly structure for a motor position detection section that is easy to assemble.

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 4 is an exploded perspective view of the entire configuration of a brushless motor equipped with a position detection section 20 as an embodiment of the present invention, and this figure shows a structure in which a stator coil 12 is wound around a yoke 11 and is supported by a metal support. It has a bobbin 10, a printed circuit board 13 equipped with a control circuit for controlling the motor drive current supplied to the stator coil 12, a button, and a bearing 14 that supports the printed circuit board 13.・
Fixed part A with bracket 15 attached to housing 14
, a rotating part B including a rotor magnet 17 magnetized in the thickness direction so that a predetermined number (for example, 4) of magnetic poles are provided on the inner circumferential surface of the magnet case 16; When the motor case 19, which is rotatably supported and held by the above-mentioned bracket, is integrally connected, and a drive current is sequentially applied to the stator coil 12 through the control circuit 4, In the magnetic field formed by this drive current, the rotating part B having the rotor magnet 17 is urged to rotate with respect to the fixed part A, and drives, for example, a capstan of a tape recorder through the shaft 18. It becomes like this.

The rotor magnet 17 of the brushless motor shown in FIG.
Since the rotor magoff 11 has four poles, a position detection element such as a Hall element, for detecting the zero rotation position (or rotation angle) of the rotor magoff 11, must be arranged as shown in FIG.

That is, since the magnetic angle in the case of four poles is twice the mechanical angle, the coil piece a, which is the reference of the stator coil 12,
The first Hall element 218 is arranged with a mechanical angle difference of 15 degrees from
, the third Hall element 21b.

21c'ffi is placed.

Furthermore, since this Hall element 21 can distinguish between S and N poles, by reversing the sign of the detection output, etc.
The position can be shifted magnetically by 180°, or mechanically by 900°.

Therefore, the third Hall element 21c' is mechanically
If it is shifted by °, the Hall element 21a.

21c' and 21b can be arranged in this order with an angular difference of 30 degrees, and can be arranged within a total angle range of 6000 degrees.

Next, a detailed assembly structure of the position detection section 20 used in the brushless motor shown in FIG. 4 will be explained with reference to FIGS. 6 to 8.

First, referring to FIG. 6, the Hall element 21, which is a position detection element, is attached to a holder 22 and fixed to the printed circuit board 13.

This printed circuit board 13 is attached to the positioning pin 2 of the holder 22.
3. Positioning hole 24 for guiding the meeting, button and this positioning hole 2
For example, the notch 25 has a fitting sound receiving part 25 in a fixed positional relationship with respect to the fitting part 4.

This notch 25 is fitted into a protrusion 26 which is a fitted part provided on the bobbin 10.

Here, the holder 22 holds three Hall elements 21,
They are fixedly arranged with an angular difference of 3 (f), respectively, and are used to fix these Hall elements 21 at a fixed position with respect to the printed circuit board 13.
It has a shape as shown in FIG.

That is, the holder 22 has the rotor magnet 170
It has three recesses 27 for guiding the Hall element, which are sequentially formed with an angular difference of 3σ in the rotational direction (direction of arrow A positioning pin 23 is implanted.

By the way, like the brushless motor to which this embodiment is applied, the Hall element 2 is provided on the end surface of the rotor magnet 17.
When arranging them to face each other, as explained in FIG. 3, it is also necessary to determine the position in the radial direction, that is, in the direction of the arrow Y in the figure.

From this, in the holder 22 of FIG. 7, the Hall element 2
1 into each recess 27 and fix it in the radial direction (arrow Y
This is undesirable because there is a possibility of displacement in the radial direction, but a holder 22 shown in FIG. 8, which is provided with a stopper piece 28 for preventing displacement in the radial direction, is preferable.

In the recess 27 of the holder 22 having the shape shown in FIG.
After fitting and fixing the Hall element 21, insert the positioning pin 23 into the positioning hole 24 of the printed circuit board 13 to fix the holder 22 and the printed circuit board 13. The button is fixed at a certain angle and radial position.

In the printed circuit board 13, the relative position of the positioning hole 24 and the notch 25 is fixed, and the notch 25
By fitting the hole element 21 into the protrusion 26 of the bobbin 10 and fixing the printed circuit board 13 and the bobbin 10, the Hall element 21 is fixed at a fixed position with respect to the bobbin 10.

As mentioned above, the bobbin 10 includes the stator coil 12
The stator coil 12 supports the yoke 11 wound with
The Hall element 21 is placed at a fixed position with respect to the stator coil 12, for example, as shown in FIG. The rotor magnet 17 is fixed in position, and the radial position is also fixed in a position where the magnetic poles of the rotor magnet 17 can be normally detected.

As is clear from the above description, the Hall element 21 is fixed at a fixed position with respect to the stator coil 12 via the holder 22, the printed circuit board 13, and the bobbin 10.

Therefore, if the positional accuracy of the recess 27 of the holder 22 and the positioning pin 23 and the positional accuracy of the hexagram and the protrusion 26 of the bobbin 10 and the stator coil 12 are high in advance when the button is pressed, the Hall element can be assembled with a simple assembly process. 21 and the stator coil 12 are automatically positioned with high precision.

Note that the present invention is not limited to the above-mentioned embodiments; for example, as a position detection element, in addition to the Hall element 21, a detection head using a coil, a magnetoresistive element, a D
ME etc. can also be used.

Also, a recess 27, a pin 23, and a hole 2 for positioning.
4. The notch 25, the protrusion 26, etc. are not limited to these,
For example, by reversing the concavities and convexities that fit into each other, the printed circuit board 1
3 may be provided with a protrusion, and the bobbin 10 may be provided with a notch. In short, it is sufficient if the respective members can be positioned with high accuracy by a simple fitting operation or the like.

Furthermore, it goes without saying that the motor to which the assembly structure of the position detection section according to the present invention is applied is not limited to two-pole and four-pole motors.

[Brief explanation of drawings]

1 to 3 are diagrams for explaining the operation of the position detection section of a three-phase, two-pole brushless morph, and FIG.
The button and FIG. 2A are schematic plan views, FIGS. 1B and 2B are graphs for explaining the energizing operation of the button in FIG. 1A and FIG. The figures show an embodiment according to the present invention, FIG. 4 is an exploded perspective view of a motor to which the embodiment is applied, FIG. 5 is a schematic plan view schematically showing the motor shown in FIG. 4, and FIG. The exploded perspective views of this embodiment, FIGS. 71 and 8, are perspective views showing different specific examples of the holder 22 of FIG. 6, respectively. 10...Bobbin, 12...Stator coil, 13...
・Flint board, 17...Rotor magnet, 21・
...Hall element, 22...Holder, 25...Notch, 26...Protrusion.

Claims (1)

[Scope of utility model registration request] a position detecting element for detecting the rotational position sound of a rotor magnet of a motor; a holder having a recess for guiding and fittingly fixing the position detecting element; and fixedly supporting the holder;
A printed circuit board having a fitting portion at a fixed position with respect to the fixed position, a control circuit provided on the printed circuit board for controlling a current for driving a motor, and a cover that fits into the fitting portion of the printed circuit board. a bobbin having a fitting part and a stator coil wound around the fixed part with respect to the fitted part; An assembly structure of a position detection section of a motor, characterized in that it is fixed at a fixed position with respect to the stator coil.