JP3238451B2 - Brushless motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor, and more particularly to an improved structure for detecting a specific rotational position of a rotor.

[0002]

2. Description of the Related Art Conventionally, an ordinary motor performs only a rotary motion. However, some devices that use a motor as a driving source may require a rotary motion and a linear motion. However, since the conventional motor only performs a rotary motion, a cam mechanism or the like is required to extract a linear motion from the rotary motion, which complicates the structure.

To solve this problem, the present applicant has previously filed Japanese Patent Application No. 3-134580. The application shows an embodiment applied to a brushless motor,
That is, as shown in FIG. 9, for example, three rows of coils 2 to 4 each including a plurality of stator coils are provided in the motor case 1 along the axial direction, and power is supplied to any one of the coil rows 2 to 4. , A rotating magnetic field is generated, and by changing the coil array to be energized, the rotor 5 is moved in the axial direction while rotating.

In order to detect the rotational position of the rotor 5 and determine the switching timing of each coil, a Hall element 7 for detecting the magnetism of the permanent magnet 6 of the rotor 5 is provided. In order to detect a specific rotational position in the rotor 5, as shown in FIG.
And a light sensor 9 comprising a light emitting element for irradiating light toward the rotor 5 and a light receiving element for receiving light from the light emitting element reflected by the mirror 8 on the motor case 1 side. .

[0005]

In the above-described brushless motor, in addition to the Hall element 7 for detecting the rotational position of the rotor 5 in order to determine the energization timing for each coil, the rotor 5
Since the mirror 8 and the optical sensor 9 are required to detect the specific rotational position of the optical sensor, the optical sensor 9 must be of a reflective type including a light projecting element and a light receiving element, which hinders miniaturization. In addition, the cost is increased.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a motor that can detect a specific rotational position of a rotor using an element that detects the rotational position of the rotor.

[0007]

According to the present invention, there is provided a brushless motor comprising: a coil array having a plurality of stator coils arranged in an axial direction;
A stator provided a plurality of rows at predetermined intervals in the direction, in the circumferential direction with a permanent magnet having a plurality magnetized magnetic so different poles alternately times
In the brushless motor having a rotor mounted for the rotation drive and the axial drive, placing a plurality of magnetic detecting elements for detecting magnetism of the permanent magnets on the stator side in isolation between predetermined in the axial direction of the rotor and detects a rotational position of the rotor by a detection signal of the magnetic detecting element, and characterized in that a structure for detecting a specific rotational position of the rotor by a phase difference between the detection signals of the plurality of magnetic detection elements Is what you do. In this case, the permanent magnet
Polar boundaries have a skew angle except at least one boundary
Configuration. Also, the shaft of the permanent magnet
The direction length is determined by a plurality of magnetic sensing elements arranged in the axial direction.
Can be configured to span at least two of the children
You.

[0008]

The rotation of the rotor is determined by the detection signal of the magnetic detecting element.
Detecting the shift position and detecting signals from multiple magnetic sensing elements.
The specific rotational position of the rotor can be detected by the phase difference between the signals.
A separate sensor to detect that particular rotational position.
No need to provide.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

In FIG. 2, reference numeral 11 denotes a cylindrical motor case, which is arranged in a vertical axis shape, and has an inner peripheral surface provided with:
For example, three annular yokes 13 to 15 of the stator 12 are fitted in three upper and lower stages.

On the inner peripheral portion of each of the stator yokes 13 to 15, three projections 13a to 15a are provided, for example, three at an angular interval of 120 degrees. Each of these projections 13a-
The 15a, stearyl of a plurality of phases, for example, a three-phase, as shown in FIG. 3
Three stator coils of the Takoiru 16a~1
6c, 17a to 17c, and 18a to 18c are wound (only the stator coils 16a to 16c are shown in FIG. 3). Then, three stator coils 16a to 16c, 17a to 17c, and 18a are arranged in each stage.
To 18c constitute coil arrays 16 to 18.

At the upper and lower ends of the motor case 11,
The bearings 19, 19 are mounted.
The shaft 21 of the rotor 20 is rotatably supported on the rotation shaft 19 and is vertically movable. The rotor 20 is configured as a permanent magnet rotor, and a permanent magnet 23 is provided on an outer peripheral portion of a core 22 fixed to a shaft 21.

The bearings 19, 19 are made of a non-magnetic material, for example, ceramics. Also, shaft 2
1 is provided with a stopper 21a for abutting on the bearings 19, 19 to regulate the movement limit position when the rotor 20 moves in the axial direction as described later.

As shown in FIGS. 1 and 4, the permanent magnet 23 is magnetized with a plurality of poles, for example, eight poles, so that the poles are alternately alternately arranged in the circumferential direction of the rotor 20. When the boundary between the adjacent different poles of the permanent magnet 23 is indicated by a broken line in FIGS. 1 and 4, an angle formed by the boundary and the rotation center line C of the rotor 20 shown in FIG. The skew angle is set to zero for one boundary line A and to a predetermined angle α for the other boundary line B. Thus, the configuration is such that one boundary A is different from the other boundary B.

On the other hand, as shown in FIG. 3, hall elements 24a to 24c and 25a as magnetic detecting elements for detecting the magnetism of the permanent magnets 23 are provided on the stator yokes 13 to 15 at the respective stages.
3 to 25c, 26a to 26c (only the upper ones are shown in FIG. 3) are arranged at a position between each of the stator coils 16a to 16c, between the stator coils 17a to 17c, and between the stator coils 18a to 18c. Has been established.

In this case, the Hall elements 24a to 26a, 24b to 26b and 24c to 26c corresponding to the upper and lower sides are respectively arranged on a straight line along the axial direction. The axial length of the permanent magnet 23 of the rotor 20 is set so as to face at least two of the three stages of Hall elements, regardless of the position of the rotor 20 within the vertical movement range. Length is set.

In FIG. 5, which shows the electric circuit configuration of the motor thus constructed, drive circuits 27 to 29 are provided.
a through 16c, 17a through 17c, and 18a through 18c are controlled to cut off the power. Since the specific control configurations of the drive circuits 27 to 29 are all the same, only the drive circuit 27 of the upper coil array 15 will be described here, and the description of the other drive circuits 28 and 29 will be omitted.

That is, the drive circuit 27 includes three pairs of a PNP transistor 30 and an NPN transistor 31. The collectors of these transistors 30 and 31 are connected to Y-connected stator coils 16a to 16c, respectively, and the emitter of the PNP transistor 31 is connected to the plus terminal of the DC power supply 32 and is connected to the NPN
The emitter of the transistor 31 is grounded. The bases of the transistors 30 and 31 are connected to a control circuit 33 constituted by a logic circuit via resistors 34, respectively.

On the other hand, Hall elements 24a to 24c, 25a
25c and 26a to 26c are detected by the sensor circuit 35.
a to 35c, 36a to 36c, and 37a to 37c. These sensor circuits 35a to 35c, 36a to 36
c, 37a to 37c are Hall elements 24a to 24c, 25
The detection signals a to 25c and 26a to 26c are amplified and compared with a reference value to form a pulse signal and input to the control circuit 33. In this case, the pulse signals are output from the Hall elements 24a to 24a.
For example, when 4c, 25a to 25c, and 26a to 26c face the N pole of the permanent magnet 23, a high-level pulse signal is output.

The control circuit 33 includes the sensor circuits 35a to 35a-3.
5c, 36a to 36c, 37a to 37c, and the stator coils 16a to 16c, 17a to
The configuration is such that the relative rotational position of the rotor 20 with respect to 17c, 18a to 18c is detected, and the switching timing of each of the transistors 30, 31 via the drive circuits 27 to 29 is determined. And each transistor 3
The switching of 0, 31 causes the stator coils 16a-16c, 17a-17c, 18a of the coil arrays 16-18.
To 18c to form a rotating magnetic field.

In this case, instead of energizing all the coil arrays 16 to 18 to form a rotating magnetic field, in the present embodiment, one of the coil arrays is selectively energized to rotate the rotating magnetic field. To form The switching of the coil array to be energized is performed when the rotor 20 rotates to a specific rotation position.

Here, a configuration for detecting that the rotor 20 has rotated to a specific rotation position will be described. That is, as described above, the axial length of the permanent magnet 23 can be set at three positions regardless of the position of the rotor 20.
c, 25a to 25c, and 26a to 26c, the length is set so as to oppose at least two stages of Hall elements. Therefore, when the rotor 20 rotates, at least two stages of Hall elements each generate a detection signal. Will be output.

The control circuit 33 is provided with three Hall elements 24a to 24c, 25a to 25c, 26a to 26 arranged in each stage for detecting a specific rotational position of the rotor 20.
c, the detection signals of one Hall element, for example, 24a, 25a, 26a, and the pulse signals from the sensor circuits 35a, 36a, 37a of the Hall elements 24a, 25a, 26a for each stage. Detect the phase difference.

On the other hand, the boundary line between adjacent different poles of the permanent magnet 23 is provided with a skew angle on all other boundary lines B except one boundary line A. When the boundary line B provided with the skew angle passes through the hall elements 24a to 26a, the sensor circuit 3 of the hall elements 24a to 26a is assumed to rotate in the direction indicated by D.
5a to 37a output pulse signals at different timings.

For example, now, one Hall element 24 in the upper stage
one Hall element 25a of the middle and a stage and outputs a detection signal. Then, when the boundary line B provided with the skew angle passes through the Hall elements 24a and 25a, there is a difference in the time when the boundary line B passes through the Hall elements 24a and 25a. Therefore, the sensor circuit 3
The timings at which the pulse signals 5a and 36a output the pulse signals are different, and have a certain phase difference E as shown in FIGS. However, the boundary line A where no skew angle is provided is defined by the Hall elements 24a and 25a.
a, the boundary line B is defined by both Hall elements 24
a and 25a simultaneously. Therefore, the pulse signals output from the sensor circuits 35a and 36a have a phase difference of zero.

As described above, the control circuit 33 detects the phase difference between the pulse signals from the sensor circuits 35a, 36a and 37a, and when the phase difference becomes zero, the rotor 20 is at a specific rotational position. It is configured to detect that.

When the rotor 20 rotates to a specific rotational position, which coil array is to be energized is determined based on a coil array designating signal input from the microcomputer 38 to the control circuit 33. That is, when the control circuit 33 detects a specific rotational position of the rotor 20, a reference position signal is input from the control circuit 33 to the microcomputer 38. The microcomputer 38 determines the number of times of input of the reference position signal and
The relationship with the order of energization of the power supply to the power supply 15 is stored in a memory (not shown), and a coil designation signal is input to the control circuit 33 according to the program.

When the switch (not shown) is turned on to start the motor as shown in, for example, FIG. After the energization, when the first reference position signal is input, the energization of the middle coil row 17 is continued. Then, when the second reference position signal is input, the middle coil array 17 is cut off and the upper coil array 16 is energized, so that the reference position signal is input. A coil array to be energized is selected every time.

When the energized coil array changes, the rotor 20 is attracted by the magnetic force formed by the energized coil array, moves in the axial direction, and moves at the position where the magnetic resistance is minimized. Stop moving. When the coil array to be energized is changed, the magnetic center of the rotor 20 changes, so that the magnetic force of the newly energized coil array attracts and moves in the axial direction, and at a position where the magnetic resistance is minimized. Stop. For example, when the energized coil array is changed from the middle coil array 17 to the upper coil array 16, the rotor 20 is attracted by the magnetic force of the upper coil array 14 and moves upward.

As a result, the height position of the upper end of the shaft 21 of the rotor 20 depends on the coil array to be energized.
It changes to three stages of F, G, upper, middle, and lower. When the coil array is energized as shown in FIG.
The height position of the upper end of F is the middle position of F until the second reference position signal is output, and the height position from the second reference position signal is output until the third reference position signal is output Changes to the upper position of the upper E. Therefore, since the rotor 20 moves in the axial direction while rotating, it can perform a rotational movement and an axial movement.

According to the present embodiment configured as described above, three upper and lower Hall elements 24a, 25 located on a straight line
The specific rotational position of the rotor 20 can be detected based on the phase difference between the detection signals of the transistors 30 and a.
1 to determine the switching timing, the stator coils 16a to 16c, 17a to 17c, 18a to 18
Hall elements 24a to 24c, 25a to 25c, 26 for detecting the relative rotational position of the rotor 20 with respect to the rotation angle c.
The specific rotational position of the rotor 20 can be detected by using a to 26c. Therefore, a sensor for detecting a specific rotational position of the rotor 20 is not required, so that the cost can be reduced and the size can be reduced.

Since the skew angle is provided at the boundary between the permanent magnets 23, the effect of smooth rotation of the rotor 20 can be obtained.

In the above embodiment, the skew angle may be provided only on one boundary line, and the skew angle may not be provided on the other boundary lines.

In the above embodiment, the detection signals of the Hall elements 24a, 25a and 26a located on the same straight line are used to detect the specific rotational position of the rotor 20, but in particular, the hall signals on the same straight line are used. It is not necessary to limit to the element.

Further, in the above embodiment, in order to make one boundary line between the different poles of the permanent magnet 23 different from the other boundary line, all the boundary lines B except the one boundary line A are skewed. The corners are provided, as shown in FIG. 8 showing another embodiment, in which one boundary line H is linearly formed along the axial direction, and the remaining boundary line J is formed by an upper half and a lower half. One boundary line H may be configured to be different from the other boundary line J by providing a step in the circumferential direction. Conversely, for one boundary line, the upper half and the lower half may be circumferentially different from each other. A step may be provided, and the remaining boundary line may be configured to be linear along the axial direction.

In the above embodiment, three coil arrays 16
18 is selectively applied to one of the coil arrays, but two or three coil arrays may be simultaneously energized. In this case, the current flowing through each coil array is The ratio may be changed. In this way, the rotor 20 has the upper end of the shaft 23 not only at the three positions of the upper position A, the middle position B, and the lower position C in the first embodiment, but also between the upper position A and the middle position B, It can be positioned between the middle position B and the lower position C, and can be displaced to any position steplessly by changing the current ratio.

[0037]

In addition, the present invention is not limited to the embodiment described above and shown in the drawings. For example, the magnetic sensing element is not limited to the Hall element, but may be a magnetoresistive element. Various changes can be made without departing from the scope of the present invention.

[0039]

According to the motor of the present invention as described in the foregoing, and detects the rotational position of the rotor by the detection signal of the magnetic detecting element, the rotor by a phase difference between the detection signals of the plurality of magnetic detection elements By adopting a configuration for detecting a specific rotational position, it is possible to detect a specific rotational position of the rotor by using an element for detecting the rotational position of the rotor, which is advantageous in that cost reduction and size reduction can be achieved. It has the effect that it has.

[Brief description of the drawings]

FIG. 1 is a development view of a permanent magnet according to an embodiment of the present invention.

FIG. 2 is an overall vertical side view.

FIG. 3 is an enlarged perspective view of a stator.

FIG. 4 is a perspective view of a permanent magnet of a rotor.

FIG. 5 is an electric circuit configuration diagram.

FIG. 6 is an output waveform diagram of a sensor circuit.

FIG. 7 is a diagram showing a state of energization of each coil array.

FIG. 8 is a view corresponding to FIG. 1, showing another embodiment of the present invention.

FIG. 9 is a diagram corresponding to FIG. 2 for comparison with the present invention.

FIG. 10 is a perspective view showing a configuration for detecting a specific rotational position of a rotor.

[Explanation of symbols]

12 is a stator, 16 to 18 are coil arrays, 16a to 16
c, 17a to 17c, 18a to 18c are stator coils, 20 is a rotor, 23 is a permanent magnet, 24a to 24c,
25a to 25c, 26a to 26c are Hall elements (magnetic detection elements), 35a to 35c, 36a to 36c, 37a to
37c is a sensor circuit.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-128654 (JP, A) JP-A-2-17944 (JP, U) JP-A 61-92181 (JP, U) JP-A 63-92181 131582 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02K 29/08 H02K 11/00 H02K 21/14

Claims (3)

(57) [Claims] 1. A coil having a plurality of stator coils.
A stator having a plurality of rows provided at predetermined intervals in the axial direction and a permanent magnet having a plurality of permanent magnets magnetized so as to be alternately different in the circumferential direction so as to be rotatable and axially driven; in the brushless motor having a <br/> over data, a plurality of magnetic detecting elements for detecting magnetism of the permanent magnets on the stator side and arranged a predetermined distance apart in the axial direction of the rotor, of the magnetic detection element A brushless motor, wherein a rotation position of the rotor is detected by a detection signal, and a specific rotation position of the rotor is detected by a phase difference between detection signals of a plurality of magnetic detection elements. 2. The permanent magnet according to claim 1, wherein the boundary between the magnetic poles is at least.
Also has a skew angle except for one boundary line
The brushless motor according to claim 1. 3. The permanent magnet according to claim 1, wherein said permanent magnet has a length in the axial direction.
At least two of the plurality of magnetic sensing elements
2. The structure according to claim 1, wherein the straddling length is set.
Or the brushless motor according to 2.