JPH03198647A - Brushless motor - Google Patents

Abstract

PURPOSE:To enable a position detecting means to be directly attached to a circuit board so as to dispense with the connection by a lead between the position detecting means and the circuit by enabling the magnetic flux of a rotor to be transmitted to the position detecting means through a magnetic substance, and providing a housing with a position detecting means on the opposite side to a stator and a rotor. CONSTITUTION:This is equipped with a stator 14, a rotor 24, which is provided on one side of a housing 10, a position detecting means (hole element), which is provided on the other side of the housing 10 and detects magnetically the rotational position of the rotor 24, and a magnetic substance 36, which is provided piercing the housing 10 and one end of which is connected magnetically to the hole element 34 and the other end of which is arranged close to the rotor 24 so that it may transmit the magnetic flux of the rotor 24 to the hole element 34. That is, since the magnetic flux of the rotor 24 can be transmitted to the hole element 34 through a magnetic substance 36, the hole element 34 can be arranged on the opposite side to the stator 14 and the rotor 24 for the housing 10. Hereby, the hole element 34 can be mounted directly on the circuit outside the housing 10, so the connection by a lead wire becomes needless.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a brushless motor, and more particularly to a brushless motor equipped with a position detection means for magnetically detecting the rotational position of a rotor.

(Prior Art) An example of a brushless motor having a position detection means for detecting the rotational position of a rotor is an ultra-high-speed scanner motor that drives a polygon mirror that scans a light beam such as a laser blink. FIG. 4 shows a sectional view of a conventional scanner motor that drives a polygon mirror. Stator 100
... are fixed to the housing 102, and a rotor 106 having a magnet ring 104 rotates outside the stator 100. polygon mirror 10
8 is fixed to the upper end of the rotating shaft 110 and rotates as the rotor 10G rotates. In order to detect the rotational position of the rotor 1.degree. 6, a Hall element 112 serving as position detection means is fixed on the inner bottom surface of the housing 102 at a position facing the lower end surface of the magnet ring 104. As the magnet ring 104 rotates on this Hall element 112, the magnetic pole centers of the magnet ring 104 approach and separate, so that the output terminal of the Hall element 112 is connected to the rotor 10.
A position signal indicating the 60th rotation position is generated, making it possible to detect the rotational position of the rotor 106. FIG. 5 shows a sectional view of a high-output motor used as a main motor of a conventional copying machine. In order to obtain a large torque in a high-output motor, the coils 202 of the stator 200 have a large amount of winding. In this motor as well, the rotational position of the magnet ring 208 of the rotor 206 is detected by the Hall element 204. FIG. 6 shows a molded motor used in a conventional air conditioner.

The stator 300... is molded with resin to form the housing 30.
2, and a rotor 304 rotates inside it. A Hall element 304 serving as a position detection means is insert-molded in the housing 302, and is capable of detecting the rotational position of the magnet ring 308 of the rotor 30G.

(Problems to be Solved by the Invention) However, the conventional brushless morph described above has the following problems.

First, in the scanner motor shown in FIG.
2 and a circuit 114 outside the housing 102 must be connected with a lead wire 116, which requires a soldering process. The board 118 mounted with the Hall element 112 inside the housing 102 and the circuit 114 outside the housing 102 must be connected by a lead wire 116.
In the case of a phase brushless motor, there are problems in that eight lead wires 116 are required, which requires a large number of man-hours for soldering, and the work efficiency of motor assembly work is low. In the high-output motor shown in FIG. 5, since the coils 202 have a large amount of windings, the height of the coil end (top end surface) is high. In this case, the magnet ring 208 is also required to be tall, which poses problems such as increased cost due to the increased size and increased inertia due to the increased dead weight of the rotor 206. In order to solve this problem, a method has been proposed that uses a short magnet ring and a vertical Hall element with extended leads as a position detection means, but due to its structure, the vertical Hall element cannot be mounted on a printed circuit board. The work efficiency is poor because an automatic mounter cannot be used in this case.

In addition, the lead has insufficient rigidity, so it easily falls over and has low reliability. Furthermore, if the Hall element 204 is provided close to the coil 202, the coil 204 with a large amount of winding can be
When a large current flows through the coils 202, accurate position detection may not be possible due to the influence of magnetic flux generated from the coils 202. Furthermore, since the amount of winding of the coils 202 is large, the amount of heat generated by the coils 202 is also large, and the Hall element 20
There is also the issue of heat-resistant treatment in step 4. Furthermore, in the case of the molded motor shown in FIG. 6, in order to position and mold the Hall element 304 at a predetermined position, it is necessary to fix the Hall element 304, and a fixing means is required. In addition, when using a vertical Hall element, the gaps between the leads are made in a staggered manner.
After that, soldering must be performed, which takes time and effort for insulation treatment, increasing manufacturing costs. Moreover, if it is molded, there is a problem that heat countermeasures cannot be taken for the Hall element 304.

Furthermore, if the Hall element 304 is damaged or misaligned, it cannot be replaced and the housing 302 and stator 3 cannot be replaced.
00... has to be discarded, which is uneconomical.

Therefore, it is an object of the present invention to provide a brushless morph that is easy to assemble, does not require heat countermeasures for the position detection means, and is inexpensive.

(Means for solving problems) In order to solve the above problems, the present invention includes the following configuration.

That is, a housing, a stator fixed to one side with respect to the housing, and a rotor provided on one side with respect to the housing and rotatably provided with respect to the stator. , a position detection means provided on the other side with respect to the housing for magnetically detecting the rotational position of the rotor; and a position detection means inserted through the housing, with one end magnetically connected to the position detection means. and a magnetic body disposed close to the rotor so as to be able to transmit the magnetic flux of the rotor to the position detection means, or a stator and the stator molded with resin. a rotor provided in the housing to be rotatable with respect to the stator; and a rotor provided outside the housing to magnetically detect the rotational position of the rotor = 7 - a position sensing means insert-molded in the housing, one end magnetically connected to the position sensing means and the other end close to the rotor so as to be capable of transmitting magnetic flux of the rotor to the position sensing means; and a magnetic body disposed in the same direction.

(effect) The effect will be explained.

Since the magnetic flux of the rotor can be transmitted to the position detecting means via the magnetic body, the position detecting means can be disposed on the opposite side of the stator and rotor with respect to the housing. Therefore, since the position detecting means can be directly attached to the circuit outside the housing, connection using lead wires is not necessary. Furthermore, even if the coil end of the stator is high in a high-output motor, the rotor can be made shorter and lighter by increasing the length of the magnetic body. Therefore, the inertia of the rotor can also be reduced. By providing the position detection means on the opposite side of the housing from the stator and rotor, or on the outside of the molded housing, the influence of heat generated by the coil can be eliminated. Furthermore, in the case of a molded motor, since the position detection means is not molded, it is possible to replace only the position detection means while leaving the stator unchanged.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, a first embodiment will be described with reference to FIG.

The first embodiment is a brushless morph used as a scanner motor for driving a polygon mirror for scanning a light beam of a laser printer.

10 is a housing, with a stator 1 at the center 12/+ circumference.
4... The coils are fitted and fixed on the outside.

Reference numeral 16 denotes a rotating shaft, which is rotatably inserted into the center hole of the center part 12 of the housing 10, and which is rotatably inserted into the center hole of the center part 12 of the housing 10.
It is supported by...

A polygon mirror 20 is attached to a boss 22 fixed to the upper end of the rotating shaft 1G, and is rotatable together with the rotating shaft 16.

A rotor 24 is made up of a rotor main body 26 in the shape of an upside-down cup, and a magnet ring 28 fixed to the inner circumferential surface of the rotor main body 26.

The inner peripheral surface and lower end surface of the magnet ring 28 are alternately magnetized with 2n N and S poles (n=natural number). The rotor main body 26 is attached to the post 22, and the rotor 24 is rotatable together with the rotating shaft 16 and, in turn, together with the polygon mirror 20.

30 is a control circuit board on which electronic components 32 are arranged and printed wiring is provided.

The substrate 30 is fixed to the lower surface side of the housing 10.

Reference numeral 34 denotes a Hall element serving as a position detection means, and is provided on the lower surface of the control circuit board 30.

The output of the Hall element 34 changes in accordance with the approach/separation of the magnetic pole center of the magnet ring 28, and a detection section (not shown) captures the change in the output and detects the rotational position of the rotor 240.

36 is a magnetic material, which is fixed by penetrating the control circuit board 30 and the housing 10. The lower end of the magnetic body 36 is in contact with the upper surface of the Hall element 34, and the upper end is located close to the lower end surface of the magnet ring 28. A gap 38 between the magnetic body 36 and the magnet ring 28 is a distance that allows the magnetic body 36 to transmit the magnetic flux of the magnet ring 28 . As a result, the magnetic body 36 at the center of the magnetic pole of the magnet ring 28
Approaching and moving away from is transmitted to the Hall element 34 via the magnetic body 36.

With the above configuration, the rotational position of the rotor 24 is detected by the Hall element 34 via the magnetic body 36 as a change in the position of the magnetic pole center due to a change in the position of the magnet ring 28.

In the case of the first embodiment, there are no circuit parts inside the housing 10 because the Hall element 34 is directly connected to the control circuit board 30 located outside the housing 10. Therefore, there is no need to connect the two circuits with lead pieces.

Next, a second embodiment will be described with reference to FIG.

The second embodiment takes a high-output brushless morph as an example.

Note that the same structural members as the first embodiment include the 11th embodiment. The same member numbers as in the first embodiment are given, and explanations thereof will be omitted.

The stators 14 are externally fitted and fixed to the center portion 12 of the housing 10. Coil 40 of stator 14...
In order to produce high output, the amount of winding is large, and the height of the coil end (upper end surface) is formed high.

The rotor 24 consists of a cup-shaped rotor body 26 and a magnet ring fixed to the inner peripheral surface of the rotor body 26, and is rotatably inserted into the center hole of the center portion 12 of the housing 10. It is fixed to the lower end of the shaft 16 via a post 22.

The ball element 34, which is a position detection means, is attached to the housing 10.
The control circuit board 30 is fixed to the top surface of the control circuit.

The magnetic body 36 is inserted and fixed into the housing 10 , has an upper end in contact with the Hall element 34 , and a lower end close to the upper end surface of the magnet ring 28 .

In the case of this embodiment, as clearly shown in FIG. 2, the position of the upper end surface of the magnet ring 28 is lower than the coil ends of the coils 40, but 2. The length of the magnetic body 36 is long. Therefore, it is sufficiently close to the magnet ring 28. Therefore, it becomes possible to use a magnet ring 28 with a short height.

Also in the second embodiment, the rotor 24 by the Hall element 34
The method of detecting the rotational position is the same. In the second embodiment, since the coil 40... has a large amount of winding, the coil 40...
. . generates a large amount of heat, but since the ball element 34 is located above the housing 10, it is not affected by the heat from the coils 40 . Further, as described above, it is possible to use a short magnet ring 28, so a lightweight and inexpensive magnet ring can be used.

Next, a third embodiment will be described with reference to FIG.

The third embodiment takes a brushless molded motor as an example. Similarly, the same component numbers as in the first embodiment are given to the same components as in the first embodiment, and explanations thereof will be omitted.

The stators 14 are molded with synthetic resin, and the synthetic resin forms the housing 10.

The rotor 24 is rotatable within the housing 10, and the rotor 24 is attached to a yoke 4 that is externally fitted and fixed to the rotating shaft 16.
2, and a magnet ring 2 externally fitted and fixed to the yoke 42.
It consists of 8.

A Hall element 34 serving as a position detection means is attached to a control circuit board 30 provided outside the housing 10.

The magnetic body 36 is insert-molded into the housing 10, with a lower end in contact with the Hall element 34 and an upper end in a position close to the outer peripheral surface of the magnet ring 28.

Also in the third embodiment, the rotor 24 by the Hall element 34
The method of detecting the rotational position is the same. In the third embodiment, the inside of the housing 10 is a closed space, and the temperature inside the housing 10 rises due to heat generated from the stators 14. However, since the Hall element 34 is provided outside the housing 10, it is not affected by heat.

Furthermore, since the Hall element 34 is not insert molded into the housing 10, only the Hall element 34 can be replaced.

In the three embodiments described above, as a method of increasing the magnetic flux transmission efficiency of the magnet rotor, the adjacent magnet ring surface of the magnetic body is also magnetized with the same number of poles as that magnetized on the surface facing the stator. This is effective. It is also effective to configure the magnetic circuit on the side of the position detecting means that is not in contact with the magnetic material, such as by using an iron substrate as the material of the printed circuit board on which the position detecting means is mounted.

Although various preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention. It is.

(Effects of the Invention) When the brushless morph according to the present invention is used, the position detection means can be provided on the side opposite to the stator and rotor with respect to the housing. Since the position detection means can be directly attached to the circuit board, there is no need to connect the position detection means to the circuit using lead wires, reducing the number of man-hours required to assemble the motor. You can try to bring it down. Further, since the position detection means is disposed on the opposite side of the housing from the stator and rotor, the influence of heat from the coil can be eliminated. Further, in the case of a high-output motor, by adjusting the length of the magnetic body, a rotor that is short in height relative to the height of the coil end can be used, and an inexpensive and lightweight rotor can be used. Regarding the brushless morph according to claim 2, since the position detecting means is located outside the housing, the influence of heat can be eliminated, and since the position detecting means is not insert molded, only the position detecting means can be replaced. play

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the first embodiment of the brushless morph according to the present invention, FIG. 2 is a sectional view showing the second embodiment, FIG. 3 is a sectional view showing the third embodiment, and FIG. ~Figure 6 is a sectional view showing a conventional brushless morph. 10... Housing, 14... Stator, 24...
...Rotor, 34...Hall element, 6-36...Magnetic material.

Claims (1)

[Claims] 1. A housing, a stator fixed to one side with respect to the housing, and a stator provided on one side with respect to the housing,
a rotor rotatably provided with respect to the stator; a position detection means provided on the other side with respect to the housing for magnetically detecting the rotational position of the rotor; and a position detection means inserted into the housing. one end is magnetically connected to the position detecting means, and the other end is provided with a magnetic body disposed close to the rotor so as to be able to transmit the magnetic flux of the rotor to the position detecting means. A brushless motor featuring 2. a stator; a housing formed by resin-molding the stator; a rotor provided within the housing so as to be rotatable with respect to the stator; and a rotor provided outside the housing and configured to rotate with respect to the stator. a position detecting means for magnetically detecting the rotational position of the rotor; and a position detecting means that is insert-molded in the housing, one end of which is magnetically connected to the position detecting means, and the other end of which transmits the magnetic flux of the rotor to the position detecting means. A brushless motor comprising: a magnetic body disposed close to a rotor so as to be able to transmit information.