JPS58207895A - Brushless motor - Google Patents

Abstract

PURPOSE:To suppress the decrease in the accuracy of a rotary speed signal to a small value by measuring the displaced time of the detection signals from the prescribed two of two or more magnetic sensors for controlling the energization of armature coils and obtaining a rotary speed signal on the basis of the result. CONSTITUTION:Hall voltages V8, V9 of Hall elements, not shown, for detecting the positions are waveform-shaped by a waveform shaper, not shown, inputted as detection signals Sa, Sb from input terminals 11a, 11b to transistors 12, 14, thereby outputting a voltage signal Sc at an output terminal 17. A period T while the voltage signal Sc is low level corresponds to the displaced time between the signals Sa and Sb, a transistor 21 which inputs at the base the signal Sc is interrupted during the period T, and a constant voltage is applied to a condenser 20 in an integrator 18. Accordingly, a rotary speed signal Sd of the sawtooth state of the period proportional to the signal Sc with the voltage inversely proportional to the period T is outputted to the output terminal 18a of the integrator 18.

Description

[Detailed description of the invention] [Technical field of invention].

The present invention relates to a brushless motor that detects the rotational phase of a rotor and sequentially energizes a plurality of phases of armature coils μ based on the detected output, and particularly includes means for generating a rotor rotational speed signal. Regarding brushless motors.

[Technical background of the invention]

In brushless motors, a rotor rotational speed signal is generated for closed loop control of the rotational speed of the rotor.In this case, a tacho generator or frequency generator generates a high-precision rotational speed signal. It is often used as something suitable for outbreaks.

[Problems with background technology]

In the conventional configuration described above, the structure of the tachogenerator or frequency generator itself is complicated, and moreover, space is required for arranging them, making the overall structure complicated, resulting in an overall high cost. Ta.

Furthermore, when the rotor rotates at a low speed, there may be problems such as the level of the rotational speed signal becoming low, making it difficult to process the signal.

[Purpose of the invention]

The purpose of the present invention is to obtain a highly accurate rotational speed signal with an extremely simple configuration using an originally existing magnetic sensor, and to solve the problem that the level of the rotational speed signal decreases even during low-speed rotation. Furthermore, even if dimensional errors, installation errors, etc. occur in the multiple permanent magnets that make up the field magnetic poles that are detected by the magnetic sensor, the reduction in accuracy of the rotational speed signal can be suppressed to a small level. We provide brushless motors.

[Summary of the invention]

The present invention provides a brushless motor equipped with a rotor having a field magnetic pole in which a plurality of permanent magnets magnetized into two or more poles are arranged in an annular manner. The magnetic sensor is characterized in that it is configured to measure the entire time difference between detection signals from two predetermined magnetic sensors, and generate a rotational speed signal based on the measurement results. The detection signal, which is the basis for generating the speed signal, is also configured to be generated based on the magnetic flux from one of the magnetic poles of the permanent magnet other than the magnetic pole located on the rotation direction side of the mouthpiece. Has characteristics.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

First, in Figures 1 and 2, 1 is a rotor, which has a cylindrical shape with a closed upper end, and has a yoke 3 with a shaft 2 passing through its center, and a plurality of rotors on the inner peripheral surface of the yoke 2. The barrel is constituted by a field magnetic pole 5 formed by attaching, for example, four permanent magnets 4 in an annular shape. In this case, each arc-shaped permanent magnet 4 has one segment self-alignment 2 as shown in FIG.
It is magnetized in its radial direction so as to have poles (N pole and 8 poles), and as a result, eight magnetic poles a to a are provided in the entire field m magnetic pole 5. Reference numeral 6.7 indicates a two-phase armature coil, which is a part of the stator (not shown), and is electrically distributed inside the rotor 1. 8.9 is a magnetic sensor, for example, a Hall lv resistor, which is provided corresponding to the armature coil (L'6.7), and these are close to the field magnetic pole-5 in its axial direction, and are connected to each other. The opening phase angle, that is, the opening angle is smaller than the minimum magnetization angle (approximately 60 s = 45 degrees in mechanical angle in this embodiment) of the magnetic poles a to ), for example, 22.5 degrees in mechanical angle. There is. The Hall μ element 8.9 is shown in FIG. V9
Output y2. At this time, the μ-elements 8 and 9 are connected to the magnetic poles a and c, d, and the pairs of magnetic poles a and d of the permanent magnet 4, respectively.
When the magnetic poles a, c, e, and g located on the rotational direction side of the rotor 1 (indicated by the arrow ■ in FIG. 2) among e, f, g, and h are opposed to each other, the negative in FIG. Lateral hornon voltage Va, Vt f, other @ poles, d, f,
When h is opposed, the Hall voltage VB in the positive direction in FIG. 5(a), V? It is configured to encourage

Now, FIG. 4 shows a signal processing circuit 1 which is a speed signal generating means.
0 is shown, and its operation will be described below with reference to FIG. That is, the Hall voltage V8
．． V9 passes through various shaping circuits as shown in Figure 5 (
Detection signal 8a having the waveform shown in b) and (e).

8b, and then applied to input terminals 11a and 11b. 12 is a first transistor which receives the detection signal 8a at its base through a resistor 13; 14 is a second transistor which receives a detection signal 8by at its base through a resistor 15; Positive power terminal + between emitter and emitter
It is connected between Vcc and the ground terminal via a resistor 16, and the collector and emitter of the second transistor 14 are connected between the base of the first transistor 12 and the ground terminal. Therefore, now, at time t1 in FIG. 5, some nine of the magnetic poles d, f, and h are opposed to the Ho/L' element 8 which is in the advanced phase position, and in the positive direction. When the Hall voltage 8 starts to be output and the detection signal 8a rises to a positive level in response to this, at this time t1, the detection signal sb is in the delayed phase.
Since the second transistor 14 that received the negative level 7 is off, the first transistor 12 is turned on. Then, the collector of the first transistor 12 falls to the ground level, and the voltage signal Sc (see FIG. 5(d)) output from the output terminal 17 connected to the collector is inverted to the low level.

After that, at time t2, the detection signal 8b rises and the second transistor 14 is turned on, and the detection signal 8a is grounded through the transistor 14 and is canceled. 12 is turned off, the voltage signal 8c is inverted to a high level. Thereafter, the voltage signal 8c is maintained at a low level until the detection signal 8a rises at time t3, and as a result, the voltage signal 8c is maintained at a low level only during the period indicated by T in FIG. Become. During this period T, the detection signal 8a
.

Since it corresponds to the deviation time of sb and indicates the time required for the rotor 1 to rotate by 22.5 mechanical angles (opening angle of Hall elements 8 and 9), the length of period T The rotational speed of the rotor 1 can be determined by measuring . On the other hand, 18 is a positive power supply terminal + which is a constant voltage source.
A resistor 19 and a capacitor 20 are connected between Vcc and the ground terminal.
21 is a transistor whose collector and emitter are connected in parallel with the capacitor 20, and the voltage signal 8C is applied to the base of the transistor 21 via a resistor 22. Therefore, the transistor 21 is turned off and a constant voltage is applied to the capacitor 20 in the integrating circuit 18 only during the period T when the voltage signal 8C is at the low level I, and as a result, a constant voltage is applied to the output terminal of the integrating circuit 18. 18a outputs a sawtooth-shaped rotational speed signal Sd (see FIG. 5(e)) having a voltage value inversely proportional to the period Tic and a period proportional to the voltage signal 8c.

The detection signals 8a, 8b are also input to a drive circuit (not shown) having a known configuration in the brushless motor, and this drive circuit receives the detection signals 8a.

By sequentially energizing the armature coils 6.7 in a predetermined order based on sb, torque is generated between the armature coils 6.7 and the field magnetic poles 5, thereby moving the rotor 1 in the direction of the arrow. I can rotate it.

According to the above-mentioned embodiment, the rotational speed signal Sd' (i7 Because of this, the structure is complicated and the cost is high compared to the conventional structure using a tachogenerator and frequency generator, and even when the rotor 1 is rotating at low speed, the level of the rotational speed signal Sd is low and the force is low. There is a strong possibility that it will happen.

Moreover, according to this embodiment, the opening angle of the H/I/elements 8 and 9 is set smaller than the minimum magnetization angle of the magnetic poles a to rotor 1, and the detection signal 8. The phase difference between a and 8b is 18 in electrical angle.
Since the angle is configured such that the angle is smaller than 0 degrees, the signal processing for generating the voltage signal 8C and eventually the rotational speed signal 8di based on the detection signals 8a and 8b can be simplified. Further, according to the present embodiment, each of the permanent magnets 4 has opposing @poles a.
and, c and d, e, flg and h, rotor 1
Since the rotational speed signal 8di is generated in accordance with the time difference between the detection signals 8a and Sb, which are damaged by the magnetic flux from the magnetic poles S, d, f, and h located on the opposite side to the rotational direction of the magnetic poles, the following effects can be achieved. can also be played. That is, in order to increase the field magnetomotive force in a brushless motor, it is desirable to divide the water magnet assembly that constitutes the field magnetic pole into multiple parts, and in this case, considering the magnetization balance, each Generally, the permanent magnet 4 is magnetized so that it has a pair of magnetic poles.However, the permanent magnet 4 has a relatively large dimensional error during manufacture, and also has a relatively large mounting error with respect to the yoke 3. In its installed state, Figure 6 (&), (
As shown in b), it is inevitable that a gap j will occur with respect to the end surface 3a of the yoke 6. Therefore, now rotor 1
Magnetic poles a and c located on the rotation direction R side.

With the configuration in which the rotational speed signal 8d is obtained based on the magnetic flux from elg, the interlinkage magnetic flux of the Hall elements 8 and 9 related to the generation of the rotational speed signal 8cl is as shown in FIG. 6(a).
There is a gap between case (b) and case (b). Therefore, the accuracy of the rotational speed signal 8d decreases! ,cormorant. On the other hand, in this embodiment, as described above, the rotational speed signal Sdy is obtained based on the magnetic flux from the magnetic poles b, d, f, and h located on the opposite side of the rotation direction hole of the rotor 1.
Hall element 8 associated with the generation of the rotational speed signal 8d.
The variation width of the magnetic flux linkage in Fig. 6 is shown in Fig. 6(a) and Fig. 6(b).
Since the amount corresponding to 1/2 of the gap l is reduced between the case of 1 and the case of , it is possible to suppress a decrease in accuracy of the rotational speed signal Sd to a small level.

In the above embodiment, a two-phase brushless motor was used as an example, but
The present invention can be applied to all brushless motors equipped with two or more magnetic sensors. Moreover, it goes without saying that the magnetic sensor (magnetic sensor) is not limited to a Hall element.

〔Effect of the invention〕

According to the present invention, as explained above, it is possible to obtain a highly accurate rotational speed signal with an extremely simple and space-saving configuration that utilizes an originally existing sensor, and the rotational speed even during low-speed rotation. Signal level μ
In addition, K suppresses the decrease in accuracy of the rotational speed signal to a small extent even when dimensional and installation errors occur in the multiple permanent magnets that make up the field magnetic poles that are detected by the magnetic sensor. It is possible to achieve effects such as:

[Brief explanation of the drawing]

The drawings relate to one embodiment of the present invention, in which Fig. 1 is a longitudinal sectional view of the main part, Fig. 2 is a bottom view of the main part, Fig. 5 is a perspective view of the permanent magnet, and Fig. 4 is a speed signal. Connection diagram of generation means, 5th
The figure is a time chart showing the signal waveform, and FIG. 6 is a diagram showing the main part expanded in a linear direction. In the figure, 1 is the rotor, 4 is the permanent magnet, 5 is the field magnetic pole, a to magnetic pole, 6.7 is the armature coil μ, 89 is the Hall element < m air sensor), and 10 is the signal processing circuit (speed (9 stages of signal generators). Applicant: Tosei Shibaura Electric Co., Ltd. Agent Patent Attorney: Gosho Sato 1 Figure 112 Figure 31!21 114 Figure s 5 Figure tl t2 t3 6th - (b) m- "-

Claims (1)

[Claims] 1. A rotor having a field magnetic pole in which a plurality of permanent magnets magnetized in two or more westward poles are arranged in a ring, and a detection signal is generated based on the magnetic flux from the field magnetic pole when the rotor rotates. output from two or more magnetic sensors, and rotates the rotor by sequentially energizing the armature coils of multiple phases based on the detection signals from the magnetic sensors, wherein the output is output from two or more of the magnetic sensors. A speed signal generating means is provided for measuring the deviation time of the detection signal and outputting a rotational speed signal of the rotor, and the speed signal generating means is located on the rotational direction side of the rotor among the magnetic poles of the permanent magnet. What is claimed is: 1. A brushless motor, characterized in that the brushless motor is configured to measure a time difference in a detection signal due to magnetic flux from magnetic poles other than the brushless motor.