JPH03226257A - Detecting method of number of rotation of motor - Google Patents

Abstract

PURPOSE:To improve the detecting accuracy of speed by a method wherein speed detecting sensors among sensors opposing to the slits of a reflecting plate for detecting magnetic position and speed are arranged with intervals equal to the 1/2 of a phase difference between the outputs of the magnetic position detecting sensors. CONSTITUTION:A reflecting plate 3, rotated synchronously with the rotor 4 of a motor, is provided with slits while a supporting plate 2, fixed to an encoder case 1, is provided with sensors 6a-6d. Slits 8a and non-slits 8b, divided equally with the equal angle of 10 deg. in circumferential direction, are formed on the reflecting plate 3 on the outer periphery of the same alternately while arced silts 10 of 30 deg., which are opposed to one of N-poles and S-poles of the rotor 4, are formed with intervals of 30 deg.. Three sets of sensors 6a-6c for detecting slits 10 are arranged on a mounting plate 2 with intervals of 15 deg. while the sensor 6d for detecting the slit 8a is arranged at a position deviated by 5 deg. with respect to the sensor 6a. According to this method, a detecting effect, equivalent to the same, in which the number of poles of the speed detecting sensor is doubled, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotation speed detection method for controlling the rotation speed of a motor in a washing machine or the like.

[Conventional technology]

As shown in Figure 4, the motor encoder device for detecting the motor rotation speed is a reflector plate (4) that rotates in synchronization with the motor rotor (4) and has slits.
3) and a sensor (6) for detecting the slit of the reflector (3) on a mounting plate (2) facing the reflector (3).
) is known. This mounting plate (2) is fixed to the encoder case (1) with a boss on the motor frame (7).

The reflector (3) is a disc that is attached to the rotor shaft (5) of the rotor (4) of the motor so as to rotate in synchronization with the rotor shaft (5). Slit divided into equal angles as a slit for speed detection (8a)
and non-slits (8b) are formed alternately. In the illustrated example, both the slit (8a) and the non-slit (8b) are 1
It has a width of 0°.

Furthermore, the reflector (3) is further provided with a magnet 30 that corresponds to either the N pole or the S pole of the rotor (4), which is a permanent magnet.
Arc-shaped slits (10) each having a width of 30 degrees were provided for detecting the magnetic pole position.

On the other hand, as shown in FIG. 6, the sensor mounting plate (2) has three sensors (6a) for detecting the slit (10).
(6b) and (6c) are arranged at equal intervals of 15 degrees on the same circumference with the same radius as the slit (10), and the slit (8
The detection sensor (6d) of a) was arranged near the outer periphery of the mounting plate (2) in parallel with the sensor (6a).

These sensors (6a) (6b
) (6c) (6d) are reflective sensors that have phototransistors that turn on and off depending on the presence or absence of reflection, and these phototransistors are connected to comparators (9a) '(9b)
(9c) Introduced in (9d).

Next, to explain the operation, when the motor rotates, the sensors (6a) (6b) (6c)
Since the positions of the slits (10) are shifted by 15 degrees, the positions of the slits (10) are detected by shifting by 15 degrees, and each sensor (6a) (6b) is detected at the timing shown in FIG.
(6c) Comparators (9a) (9b) (9
c) to detect the magnetic pole position of the rotor (4).

This digitalized magnetic pole position detection signal becomes a signal for rotating the motor, and if the motor is a DC brushless motor, for example, it is introduced into a control device to control the voltage controller of the motor using a transistor module.

In addition, in the sensor (6d), the slit (8a) and the non-slip (8b) are alternately located, and the reflective state and non-reflective state appear alternately, and the sensor (6d) is in the reflective state and the internal circuit is The transistor turns on and turns off in a non-reflective state.

This on/off signal is input to the input terminal of a comparator (9d), where this on/off signal is compared with a reference voltage to produce a rectangular wave output signal as shown in output 4 in Figure 8. Therefore, the rotation speed is calculated by inputting it into the control device.

[Problem to be solved by the invention]

This is how you install a conventional motor encoder! In the method for detecting the rotational speed of a motor, speed detection is performed using a slit (8a) and a non-slit (8b), which are equally angularly divided in the circumferential direction on the outer periphery of a reflector (3), and a sensor (8b) corresponding to the slit (8a) and non-slit (8b). 6d), but for fine speed control, slit (8a) and non-slit (8a)
It is necessary to increase the number by decreasing the equal division angle with 8b).

In particular, in a washing machine, the stirring operation is performed by swinging the washing blades by the motor, and the motor performs speed control of forward and reverse operations within a range of less than one rotation, resulting in fine speed control as described above.

However, there is a limit to increasing the number of slits (8a) and non-slits (8b), the so-called number of poles, due to the detection ability of the sensor (6d) and the overall size of the encoder device.

An object of the present invention is to eliminate the disadvantages of the conventional example, obtain the same effect as doubling the number of poles in a motor encoder device, and provide a motor rotation speed detection method that enables fine-grained speed detection. Our goal is to provide the following.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a reflector plate that rotates in synchronization with the rotor of a motor and has a slit, and a sensor for detecting the slit of the reflector plate, which is disposed on a mounting plate facing the reflector plate. In a motor rotation speed detection method using a motor encoder device, there are two types of slits in the reflecting plate: a slit for detecting the magnetic pole position and a slit for speed detection, and the slit for speed detection corresponds to the slit for speed detection. The sensor is placed at 1/2 the phase difference between the magnetic pole position detection sensor corresponding to the magnetic pole position detection slit and the detection signal between the magnetic pole position detection sensors, and both the magnetic pole position detection signal and the speed detection signal are used. The purpose is to detect motor speed.

[Effect]

According to the present invention, the motor speed is detected using both the magnetic pole position detection signal and the speed detection signal, and since the speed detection sensor is located at 1/2 of the phase difference of the magnetic pole position detection signal, the speed detection sensor The same detection effect as doubling the number of poles can be obtained.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

Fig. 1 is a plan view of a reflector plate showing an embodiment of the motor encoder device used in the motor rotation speed detection method of the present invention, and Fig. 2 is a plan view of the same sensor mounting plate, showing the overall configuration of the encoder device. Since this is the same as that already explained with respect to the conventional example shown in FIG. 4, detailed explanation will be omitted here.

A disc-shaped reflector (3) that rotates in synchronization with the rotor shaft (5) of the rotor (4) of the motor is attached to the rotor shaft (5) of the motor rotor (4). Divided slits (8a) and non-slits (8b) are formed alternately, and the reflecting plate (3) is arranged to correspond to either the N pole or the S pole of the rotor (4), which is a permanent magnet. 30
This is the same as the conventional example shown in FIG. 5 in that the degree arc-shaped slits (10) are provided with a width of 30 degrees from each other. That is, the reflecting plate (3) may be the same as the conventional one.

On the other hand, as shown in Fig. 2, the sensor mounting plate (2) has
Three sensors (6a) for detecting the slit (10)
(6b) (6c) are arranged at equal intervals of 15 degrees on the same circumference with the same radius as the slit (10), and the slit (
The detection sensor (6d) of 8a) is arranged near the outer periphery of the mounting plate (2);
Assume that the position is shifted by 5 degrees from 6a).

In this way, when the motor rotates, the sensor (6
a), (6b), and (6c) are each shifted by 15 degrees, so the position of the slit (10) is detected by shifting by 15 degrees, and each sensor (6a) is detected at the timing shown in Fig. 3.
(6b) Comparator (9a) of (6c)
(9b) From (9c), the outputs 1 to 3) detect the magnetic pole position of the rotor (4).

This digitized magnetic pole position detection signal becomes a signal for rotating the motor, and for example, if the motor is a DC brushless motor, it is introduced into a control device to control a voltage controller of the motor using a transistor module.

In addition, in the sensor (6d), the slit (8a) and the non-slit 1-(8b) are alternately located, and the reflective state and the non-reflective state appear alternately, and the sensor (6e) is in the reflective state and the internal circuit The transistor turns on and turns off in a non-reflective state.

This on/off signal is input to the input terminal of a comparator (9d), where this on/off signal is compared with a reference voltage to produce a square wave output signal as shown in output 4 in Figure 3. However, by looking at the phase difference between the rising edges of this output 4 and the outputs 1 to 3, we can determine the value of 5 degrees, which is half of 10 degrees, due to the slit (8a) of output 4 [Y=X/ at output 4 in Figure 3] 2
) can be detected.

〔Effect of the invention〕

As described above, the method for detecting the rotational speed of a motor according to the present invention rotates in synchronization with the rotor of the motor, the slit is a reflector, and the sensor for detecting the slit of the reflector is opposed to the reflector. When using the motor encoder device installed on the mounting plate, the same detection effect as doubling the number of poles of the speed detection sensor can be obtained, making detailed speed detection possible with an inexpensive device. It is what it is.

[Brief explanation of drawings]

Fig. 1 is a plan view of a reflector showing an embodiment of the motor encoder device used in the motor rotation speed detection method of the present invention, Fig. 2 is a plan view of the same sensor mounting plate, and Fig. 3 is a plan view of the comparator. A waveform diagram of the output signal, Fig. 4 is a partially cutaway side view of the motor encoder device, Fig. 5 is a plan view of a conventional reflector, Fig. 6 is a plan view of the same sensor mounting plate, and Fig. 7 8 is a circuit configuration diagram of a sensor, and FIG. 8 is a timing diagram of an output signal of a comparator showing a conventional example. (1)...Encoder case (2)...Mounting plate (3)...Reflector plate (4)...Rotor (5
)...Rotor shaft (6) (6a) to (6d)...Sensor (7)
... Motor frame (8a) ... Pickpocket (8b)
...Non-slit (9a) to (9d)...Comparator (10)...
·slit

Claims (1)

[Claims] A motor that uses a motor encoder device that rotates in synchronization with the rotor of the motor and includes a reflector having slits, and a sensor for detecting the slits in the reflector, which is disposed on a mounting plate facing the reflector. In the rotation speed detection method, there are two types of slits in the reflector: slits for magnetic pole position detection and slits for speed detection, and the speed detection sensor corresponding to the slit for speed detection corresponds to the slit for magnetic pole position detection. The magnetic pole position detection sensor is arranged at 1/2 the phase difference between the detection signals of the magnetic pole position detection sensors, and the motor speed is detected using both the magnetic pole position detection signal and the speed detection signal. How to detect motor rotation speed.