JPH0521980Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention relates to a flat motor, in particular, a disk-shaped magnet is magnetized in the axial direction and rotatably supported on the rotor side, and this magnet is magnetized in the axial direction. The present invention relates to a flat type motor which is arranged to face a fixedly arranged stator coil through an air gap in the direction.

〓Summary of the invention〓 The invention consists of disposing a rotor yoke for guiding the magnetic flux generated by the magnet that constitutes the rotor of a flat motor on the side opposite to the magnet with respect to the stator coil. A ring-shaped stator yoke is provided to face each other, and the axial suction force generated between the stator yoke and the magnet applies preload to the bearing that rotatably supports the rotor. In addition to minimizing iron loss, the amount of preload can be arbitrarily set depending on the inner diameter of the stator yoke.

<Prior art> For example, as disclosed in Japanese Utility Model Publication No. 52-170, a flat motor has a disk-shaped magnet that is magnetized in the axial direction and rotatably supported on the rotor side. It has a structure in which a magnet is opposed to a fixedly arranged stator coil via an axial air gap. When a ball bearing is used to rotatably support the rotor of such a motor, there is a clearance between the inner and outer rings of the ball bearing and the balls, so a preload is applied to remove this clearance. It is necessary to give it.

〓Problems to be solved by the invention〓 A common method of applying preload is to insert a coil spring between the outer rings of a pair of ball bearings, and apply the preload using the elastic restoring force of this spring. It is. However, such a structure cannot be adopted unless there is sufficient space. In addition, when one of the bearings is constructed of a sintered bearing, a coil spring cannot be used, so the preload must be applied using the attractive force between the stator yoke and the magnet. However, according to such a preloading method, iron loss occurs due to the stator yoke, and power consumption increases. Furthermore, according to such a preloading method that uses the attraction force of a magnet, if the magnet has a large external shape or is made of rare earth metal, the attraction force will be too large and the life of the bearing will be shortened. Alternatively, unnecessarily large bearings may be used to withstand large suction forces. Furthermore, the conventional preloading method using the attraction force of a magnet has the disadvantage that it is difficult to adjust the amount of preload.

The present invention was developed in view of these problems, and it is a flat type that minimizes the iron loss caused by the stator yoke and also allows preload to be applied to the bearing by arbitrarily adjusting the amount of preload. The purpose is to provide motors.

〓Means for solving the problem〓 The present invention magnetizes a disk-shaped magnet in the axial direction, and magnetizes the outer periphery of the magnet for rotation detection, rotatably supports it on the rotor side, and The flat motor is configured such that the magnet faces a stator coil fixedly arranged on a printed wiring board via an air gap in the axial direction, and the magnet is magnetized for detecting rotation of the printed wiring board. a rotor yoke for guiding the magnetic flux generated by the magnet is arranged on the opposite side of the magnet with respect to the stator coil; A ring-shaped stator yoke is provided so as to face the magnetized outer peripheral end surface, and this stator yoke rotatably supports the rotor by an axial attraction force generated between the stator yoke and the magnet. The present invention relates to a flat type motor, characterized in that the rotation detection output obtained from the rotation detection pattern is increased by applying preload to the bearing and closing the magnetic flux generated in the magnetized portion for rotation detection with the stator yoke. It is something.

<Effect> When the stator coil is energized, the current flowing through this coil interlinks with the magnetic flux generated by the magnet on the rotor side, causing the rotor to rotate under the rotational force. By switching the current in the stator coil in accordance with the rotation of the rotor, the rotor including the magnets is rotated.

Moreover, the axial attraction force generated between the stator yoke and the magnet applies preload to the bearing that rotatably supports the rotor.
Further, the magnetic flux generated in the magnetized portion for rotation detection is closed by the stator yoke, and the rotation detection output obtained from the rotation detection pattern is increased by the stator yoke.

〓Example〓 The present invention will be described below with reference to an illustrated example.
FIG. 2 shows a flat type motor according to an embodiment of the present invention, and this motor is equipped with a case 10 that also serves as a mechanical chassis. This case 10 is formed with a boss portion 11 whose center is a through hole, and an upper ball bearing 12 and a lower sintered bearing 1 are mounted on this boss portion 11.
A support shaft 14 is rotatably supported via 3. A chuck boss 15 is press-fitted onto the upper end of the support shaft 14, and is used to rotate, for example, a magnetic disk.

A rotor boss 1 is attached to the lower end of the support shaft 14 which is rotatably supported by a pair of bearings 12 and 13.
6 is fixed by press fitting. A rotor magnet 17 is attached to the rotor boss 16. That is, magnet 1
The rotor magnet 17 is attached to the rotor boss 16 with the lower end surface of the rotor magnet 17 in contact with a reference surface 18 consisting of a stepped portion, and the rotor case 19 is placed on top of the rotor magnet 17. Further, a rotor yoke 20 is fitted and attached to the lower end side of the rotor boss 16. The magnet 17 held in this manner has eight poles as shown in Fig. 3, and the segment-shaped portions that make up each pole are magnetized so that both ends in the axial direction have different poles. has been done. Further, the outer circumferential side of this magnet 17 is magnetized for FG.

As shown in FIGS. 1 and 2, a printed wiring board 25 is placed below the magnet 17.
are arranged. And this printed wiring board 2
As shown in FIG. 4, six motor coils 26 to 31 are arranged circumferentially at 60 degree intervals on the motor 5, and are opposed to the magnet 17 through an air gap in the axial direction. ing.
Note that an FG pattern is formed on the upper surface of the printed wiring board 25 including the motor coils 26 to 31. Further, a suction yoke 32 is disposed below the printed wiring board 25 so as to suppress the outer periphery of the coils 26 to 31. This yoke 32
The rotor is sucked downward by using the suction force of the magnet 17, and a preload is applied to the upper ball bearing 12. The yoke 32 is coupled to the case 19 together with the printed wiring board 25 by screws 33.

Next, as shown in FIG. 5, the motor coils 26 to 31 on the printed wiring board 25 include coils 26, 29, coils 27, 30, and The coils 28, 31 are connected in series with each other, and the series circuit of each pair of coils is connected to the power supply side via transistors 41, 43, 45, respectively, and transistors 42, 44,
46 to the ground side. The base of the transistors 41 and 42 is an inverting amplifier 47.
The bases of transistors 43 and 44 are connected to the positive and negative terminals of inverting amplifier 48, and the bases of transistors 45 and 46 are connected to the positive and negative terminals of inverting amplifier 49. are connected to each other. And these amplifiers 47, 48,
49 are both connected to a logic circuit 53. This logic circuit 53 is connected to three Hall elements 50, 51, and 52 that detect the rotational position of the magnet 17.

In the above configuration, the three Hall elements 50 to 52 connected to the logic circuit 53 shown in FIG. 5 are adapted to detect the rotational position of the magnet 17 held by the rotor boss 16. The detection output is supplied to a logic circuit 53. The logic circuit 53 forms three sine waves whose phases are shifted by 120 degrees from each other based on the detection of these three Hall elements 50 to 52, and inverts these inverting amplifiers 47, 48, 49.
We are trying to supply each. The first inverting amplifier 47 is supplied with a sine wave without delay, and the second inverting amplifier 48 is supplied with a sine wave whose phase is delayed by 120 degrees. Then, the third inverting amplifier 49 is supplied with a sine wave whose phase is delayed by 240 degrees.

The three inverting amplifiers 47, 48, and 49 each amplify the input sine wave and output it as it is from the positive side terminal, and also invert the input sine wave and output it from the negative side terminal. In other words, the first inverting amplifier 47 amplifies the output of the logic circuit 53 with no phase lag and supplies the output to the base of the transistor 41. In contrast, the first inverting amplifier 47 supplies a sine wave obtained by inverting this output to the base of the transistor 41. I am trying to supply it to 42 bases. Similarly, the inverting amplifier 48 supplies an output with a phase delay of 120 degrees to the base of the transistor 43, and also supplies a sine wave obtained by inverting this to the base of the transistor 44. Similarly, the inverting amplifier 49 supplies a 240 degree phase-shifted sine wave to the base of the transistor 45, and also supplies the inverted sine wave to the base of the transistor 46.

The two sets of coils connected in series are connected to each other at one end, and the other end is connected to the connection point between transistors 41 and 42, the connection point between transistors 43 and 44, and transistor 4.
5 and 46, respectively. Therefore, these coils 26, 29, coils 27, 30, and coils 28, 31 are 120
The current is applied in a manner that is shifted from each other by degrees, and the direction of current flow is reversed. For example, when the transistors 41 and 44 are electrically connected, a current flows from the power supply side through the transistor 41 to the coils 29 and 26, and further this current flows through the coils 27 and 30 and the transistor 44 to the ground side. become. On the other hand, when the rotational position is shifted and at a certain rotation angle, the transistor 42 and the transistor 4
3 conducts, transistor 4 is connected from the power supply side.
3. Current flows in the order of coils 30 and 27, coils 26 and 29, and transistor 42, and the direction of the current is reversed from the above case.

In this way, the currents flowing through the six coils 26 to 31 interlink with the magnetic flux generated by the rotor magnet 17, so that the rotor receives rotational force and rotates. In this way 6
The 3-phase brushless motor with 8 coils and 120 degree bidirectional current flow generates rotational force, and this output drives the magnetic disk to rotate through the chuck boss 15, for example, or through a transmission means (not shown). It will be taken out to the outside.

Furthermore, in the flat type motor according to this embodiment, an attraction force is generated between the rotor magnet 17 by the attraction stator yoke 32, and
Preload is applied to the upper ball bearing 12. Stator yoke 32 is magnet 1
Since it faces the lower end surface on the outer circumferential side of 7, a magnetic attraction force is generated between the two. Therefore, this makes it possible to attract the support shaft 14 downward, and generates a preload force that urges the inner ring of the ball bearing 12 downward.
It becomes possible to eliminate the clearance between the balls of No. 2 and the inner and outer rings. Therefore, such a structure allows the rotor to rotate smoothly without wobbling in the thrust direction.

The suction stator yoke 32 that gives preload to the ball bearing 12 in this way has an inner diameter of
That is, by arbitrarily selecting the value of the dimension D in FIG. 4, it is possible to adjust the attraction force between the rotor magnet 17 and the optimum preload amount in the thrust direction. It becomes possible to set it so that it occurs. It should be noted that if the stator yoke 32 is made of a silicon steel plate, the iron loss will be reduced, but there is no particular problem if the stator yoke 32 is made of a steel plate. and magnet 1
Since most of the magnetic flux generated in the rotor yoke 7 passes through the rotor yoke 20 disposed inside the opening of the stator yoke 32, iron loss is extremely reduced and power consumption is also reduced. Furthermore, as shown in Fig. 3, the magnet 17 of this motor is magnetized on its outer circumferential side for FG in order to obtain an output with a frequency proportional to the rotational speed. Even if preloading is carried out, it is possible to carry out preloading by the stator yoke 32. In this case, since the magnetic flux generated in the magnetized portion for FG is closed by the stator yoke 32, the FG output obtained from the FG pattern formed on the top surface of the printed wiring board 25 increases. become.

Furthermore, the bearing 12 of the motor according to this embodiment
According to the preload, even if one ball bearing 12 is supported by a sintered bearing 13 and the other is supported by a sintered bearing 13, as shown in FIGS. You will be able to give Therefore, it is possible to reduce costs compared to the case where two ball bearings are used. Furthermore, even when using a motor with a large outer diameter of the magnet 17 or a magnet with a large attraction force such as a rare earth magnet, the attraction force can be reduced by increasing the inner diameter D of the stator yoke 32. This makes it possible to avoid applying an unnecessarily large preload to the bearing 12. Therefore, from this, it is possible to extend the life of the ball bearing 12, or it is not necessary to use a ball bearing of an unnecessarily large size.

Although the present invention has been described above with reference to an illustrated embodiment,
The present invention is not limited to the above embodiments, and various modifications can be made based on the technical idea of the present invention. For example, in the above embodiment, the printed wiring board 25 is disposed below the magnet 17, and the coils 26 to 31 are supported on the lower surface of the printed wiring board 25. Coil 26 on the top surface of
- 31 may be mounted so that the coils 26 - 31 directly face the magnet 17.
Even in such a case, by attaching the suction stator yoke 32 to the lower surface of the printed wiring board 25, it is possible to achieve the same effects as in the above embodiment.

Effects of the invention As described above, the present invention magnetizes a disc-shaped magnet in the axial direction, magnetizes its outer circumference for rotation detection, rotatably supports it on the rotor side, and It is a flat type motor in which a magnet faces a stator coil fixedly arranged on a printed wiring board via an air gap in the axial direction, and the outer peripheral side is magnetized for detecting the rotation of the magnet on the printed wiring board. A rotation detection pattern is formed at a position corresponding to the stator coil, and a rotor yoke for guiding the magnetic flux generated by the magnet is placed on the opposite side of the magnet with respect to the stator coil. A ring-shaped stator yoke is provided to face the side end face, and the axial suction force generated between this stator yoke and the magnet applies preload to the bearing that rotatably supports the rotor. The rotation detection output obtained from the rotation detection pattern is increased by closing the magnetic flux generated in the magnetized portion for detection with the stator yoke.

Therefore, according to the present invention, it is possible to apply preload to the bearing that rotatably supports the rotor by the axial attraction force generated between the stator yoke and the magnet. Moreover, the magnitude of the preload applied to the bearing in this way can be set to an optimal value by arbitrarily selecting the dimension of the inner diameter of the stator yoke. Furthermore, since most of the magnetic flux generated by the magnet passes through the rotor yoke, it is possible to reduce iron loss and create a motor with low power consumption, and it is no longer necessary to apply an unnecessarily large preload to the bearings.

In addition, according to the present invention, the magnetic flux generated in the magnetized part for rotation detection formed on the outer circumference of the magnet is closed by the ring-shaped stator yoke, and the rotation detected by the rotation detection pattern is closed by the ring-shaped stator yoke. The detection output will be increased. Therefore, using such a rotation detection output, it is possible to reliably control the rotation of the motor.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of the main parts of a motor according to an embodiment of the present invention, and FIG. 2 is a vertical cross-sectional view of the entire motor.
Figure 3 is a plan view of the magnet of this motor, Figure 4
The figure is a bottom view of the motor, and FIG. 5 is a circuit diagram showing the drive circuit of this motor. In addition, in the symbols used in the drawings, 12... Ball bearing, 14... Support shaft, 16... Rotor boss, 17... Rotor magnet, 19... Rotor case, 20... Rotor yoke, 25... Printed wiring board, 26-31...Motor coil, 32
...It is a stator yoke for suction.

Claims (1)

[Scope of Claim for Utility Model Registration] A disc-shaped magnet is magnetized in the axial direction, and its outer circumference is magnetized for rotation detection, rotatably supported on the rotor side, and this magnet is magnetized in the axial direction. A flat type motor which is arranged to face a stator coil fixedly arranged on a printed wiring board via an air gap, and corresponds to the outer peripheral side of the printed wiring board where the magnet is magnetized for rotation detection. A rotation detection pattern is formed at a position, a rotor yoke for guiding the magnetic flux generated by the magnet is arranged on the opposite side of the stator coil from the magnet, and the magnet is magnetized for rotation detection. A ring-shaped stator yoke is provided to face the end surface on the outer peripheral side, and this stator yoke applies preload to a bearing that rotatably supports the rotor by an axial suction force generated between the stator yoke and the magnet. In addition, a flat motor characterized in that the rotation detection output obtained from the rotation detection pattern is increased by closing the magnetic flux generated in the magnetized portion for rotation detection with the stator yoke.