JPH03145958A - Rotating position detector of rotating body - Google Patents

Abstract

PURPOSE:To obtain a pulse signal of 50% of the duty ratio by shifting the ratio of forming angle area of a light shielding section to a light transmitting section of a rotating disc from 1:1 and controlling the forming angle area of the light shielding section and light transmitting section, thereby correcting the timing of light receiving operation. CONSTITUTION:When a light receiving section 25 performs a light receiving operation even if an opening rate of a window section 25a is less than 50%, a tooth section 22 is formed in a forming angle area larger than a notch section 23. While, when the light receiving section 25 doesn't perform light receiving operation unless the opening rate of the window section 25a is more than 50%, the tooth section 22 is formed in the forming angle area smaller than the notch section 23. At that time, the forming angle area of the tooth section 22 increases as the opening rate of the window section 25a performing the light receiving operation of the light receiving section 25 decreases.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a rotational position detection device for a rotating body using a rotating disk and a photointerrupter.

(Prior Art) Conventionally, as a rotational position detecting device for detecting the position of a rotating body, such as a rotor of a motor, magnetic type and optical type have been provided. With the recent demand for downsizing of devices, optical type rotational position detection devices are increasingly being adopted because magnetic type ones have various adverse effects due to magnetic leakage. In particular, among variable reluctance motors, SR motors (5vl
In the case of a ched reluctance motor (ched reluctance motor), a photointerrupter is used because strict timing is required for turning on and off the windings of each phase.

This type of rotational position detection device is composed of a rotating disk fixed to the rotating shaft of the rotor and a photointerrupter fixedly arranged on the stator side. For example, the number of stator teeth is 6.
FIG. 5 shows a specific example in which the rotor is incorporated in a three-phase excitation variable reluctance morph having four rotor teeth and obtains four pulse signals in one rotation. That is, four teeth 2 for blocking light are formed on the outer periphery of the rotating plate 1, and the portion other than the teeth 2 becomes a cutout 3 that allows light to pass through. At this time, tooth portion 2. Both notches 3 are formed in a 45° forming angle region. On the other hand, although not shown in detail, the photointerrupter 4 is fixedly arranged between a light emitting part and a light receiving part 5 which are arranged oppositely, so as to sandwich the outer circumferential part of the rotating disk 1, and a window of the light receiving part 5. 5a is positioned corresponding to the 11+1 rolling locus of the tooth portion 2. In this device, a rotating disk 1 that rotates together with a rotor repeatedly blocks light through a window 5a to a light receiving section 5 of a photointerrupter 4, and a duty ratio of 50% is obtained from the light receiving section 5. It is configured to output a pulse of 1°. Based on this pulse signal, the energization control device controls energization and disconnection of the windings of each phase.

(Problem to be Solved by the Invention) By the way, in the variable reluctance motor as described above, the relationship between the rotor position and the torque is as follows, considering the torque only in the - phase, as shown in the seventh sentence. A counter-torque will be produced every 45" relative to the rotor position. Therefore, to rotate the rotor in one direction,
The winding current must be turned on and off every 450 steps of the rotor.

As for the torque characteristics, as shown in Fig. 8, the angle of torque generation can be varied within a range of 45'' by changing the tooth width of the stator, and as shown in Fig. 7. It is known that the phase of torque generation can be changed earlier or later by changing the tooth width of the rotor.Therefore, by designing the motor according to the application, the electrical time constant can be kept small and averaged. I+J is capable of responding freely to applications that require increased torque or applications that require large electrical time constants to be used efficiently.

However, in the case of the above-mentioned conventional device in which the forming angle area of the tooth portion 2 and the notch portion 3 of the rotary disk 1 is fixed at a ratio of 1:1 and each is mechanically formed at 45°, the light receiving portion Due to the difference in sensitivity of the light receiving elements No. 5, the duty ratio of the output pulse signal may not be exactly 50%. That is, when the sensitivity of the light receiving section 5 is good, the light receiving operation will start even if the window section 5a is slightly opened, and the light receiving operation will not stop unless the large 14 of the window section 5a is closed. On the other hand, if the sensitivity of the light receiving section 5 is poor, the light receiving operation will not work unless the large part of the window section 5a is opened, and the light receiving operation will stop even if the window section 5a is slightly closed. . FIG. 6 schematically shows the operating status of the light receiving section 5 at this time. Originally, as shown in FIG. 5(a), the center of the window 5a of the light receiving section 5 was at the 0 point (opening ratio 50 %), the light receiving operation is turned on and off, and a pulse signal with a duty ratio of 50% is output. However, when the sensitivity of the light receiving section 5 is good, as shown in FIG.
The timing of light receiving operation (on) is early, and the timing of stopping (off) is delayed by one, and the off time becomes shorter than the on time, and a pulse signal that deviates from one to one is output. In addition, if the sensitivity of the light receiving section 5 is poor, the same figure (
As shown in c), pulse No. 13 opposite to the above will be output.

Such a shift in the duty ratio of the pulse signal does not have much of an adverse effect if the diameter of the rotating disk 1 is sufficiently large compared to the width of the window 5a of the light receiving section 5, but in recent years With the miniaturization of the disk 1, the deviation has become so large that it cannot be ignored. In particular, as described above, in the case of a reluctance morph in which the stator tooth width and the rotor tooth width are increased, a small deviation in the energization timing will lead to the generation of a large counter torque.

As a result, problems such as a significant drop in efficiency and the occurrence of torque ripples will open up, and if these problems are to be avoided, the degree of freedom in motor design will be restricted.

The present invention has been made in view of the above-mentioned (1) If situation, and its object is to provide a rotational position detecting device for a rotating body that can obtain a pulse signal with a duty ratio of 50%.

[Structure of the Invention] (Means for Solving the Problem) The rotational position detection device for a rotating body of the present invention allows the light receiving section of the photointerrupter to receive light even when the window opening ratio is less than 50%. 1]! The light-shielding part of the one-turn disc is formed in a larger forming angle area than the light-transmitting part, and the light-receiving part does not perform light-receiving operation unless the opening rate of the window part exceeds 50%. In this case, the feature 1-j is that the light-shielding portion of the rotating disk is formed in a smaller forming angle area than the light-transmitting portion.

(Function) Conventionally, in order to output a pulse signal with a duty ratio of 50% from a photointerrupter, it is a matter of course that the ratio of the forming angle areas of the light-shielding part and the light-transmitting part of the rotating ITJ board is 1:1. 4 was given. However, due to improvements in the quality of the light-receiving elements constituting the light-receiving section and the miniaturization of devices, there have been many cases in which this method cannot handle cases where strict output signals are required.

The present inventors focused on forming the rotating disk with the ratio of the formation angle area of the light-shielding part and the light-transmitting part being shifted from 1:1,
The relationship between the aperture ratio of the window and the light-receiving operation In other words, the angle range formed by the light-blocking part and the light-transmitting part is adjusted depending on the sensitivity of the light-receiving part, and the timing of the light-receiving operation is corrected, so to speak. It was confirmed that by shifting, it was possible to output a pulse signal with a duty ratio of 50%.

In other words, as in the above-mentioned means, when the light-receiving section performs the light-receiving operation even when the aperture ratio of the window is less than 50%, the area of the rotating disk that performs the light-receiving operation, i.e. By making the formation angle range of the light-transmitting part narrower than that of the light-blocking part, the pulse signal is corrected in a direction closer to the duty ratio of 50%.

On the other hand, if the light receiving part does not receive light unless the aperture ratio of the window exceeds 50%, If it is made wider than the light shielding part, the pulse signal is corrected in a direction approaching a duty ratio of 50%. In other words, as the aperture ratio of the window section through which the light receiving section performs the light receiving operation becomes smaller, the angular region in which the light shielding section is formed becomes larger. Therefore, according to the above means, a pulse signal with a duty ratio of 50% can be obtained.

(Example) Hereinafter, an example in which the present invention is applied to a rotational position detecting device for a rotor of a 01 variable reluctance motor will be described with reference to FIGS. 1 to 4. Here, the number of stator teeth is 6. A case where the rotor is incorporated into a three-phase excitation variable reluctance morph with four rotor teeth will be described.

FIG. 3 shows the overall configuration of the variable reluctance smorph 11, in which a rotating shaft 13 is disposed in the casing 12 at the zero rotation angle, and the rotating shaft 13 has a salient pole shape as shown in FIG. The laminated cores 14 are press-fitted to form a rotor 15, which is a rotating body. On the other hand, on the outer peripheral side of the rotor 15, a stator 17 having a winding 16 wound thereon is arranged. A well-known rotational speed detector 18 consisting of an encoder disk 18a and an MR sensor 18b is provided on the base end side of the rotating shaft 13, and a rotational position detection device 19 according to the present embodiment is provided. There is.

As shown in FIG. 1, this rotational position detection bag ff19 is composed of a rotating disk 20 attached to the rotating shaft 13 and a well-known photointerrupter 21 fixedly arranged on the stator 17 side. . Of these, the rotating disk 20 has four toothed portions 22, which are light shielding portions, formed at equal intervals on the outer periphery, and the earthen floor of these toothed portions 22 serves as four cutout portions 23, which are transparent holes. There is. As a result, tooth portions 22 and notches 23 are alternately formed on the outer periphery of the rotating disk 20 in the circumferential direction. Further, the forming angle area a of the tooth portion 22 and the forming angle area a of the notch portion 23 are formed at angles as will be described later, and the sum C of the forming angle areas of the tooth portion 22 and the notch portion 23 is 90 It is @. On the other hand, as shown in FIG.
5a (see FIG. 1) and are arranged opposite to each other with a gap of 7f. and,
The rotating disk 2 is located between the light projecting section 24 and the light receiving section 25.
They are arranged across the outer circumference of 0.

At this time, as shown in FIG.
a is located corresponding to the 1!1 rotation locus of the tooth portion 22.

Although not shown in detail, this photointerrupter 21
are arranged at an interval of, for example, 30" in mechanical angle. Thereby, the rotational position detection device 19 detects that the rotary disk 20 is aligned with the photointerrupter 21 as the rotor 15 moves forward. The structure is such that the light received by the light receiving section 25 is repeatedly blocked and transmitted in a ratio of 1:'1, and a pulse signal is output based on the light receiving operation and the stoppage of the light receiving section 25. Based on this output signal, an energization control device (not shown) controls energization/disconnection of the winding 16 of each phase.

Now, the tooth portion 22 and the notch portion 23 of the rotating disk 20 are as follows.
The forming angle regions a and b are formed as follows.

That is, the light receiving section 25 has an opening rate of 50% of the window section 25a.
If the light-receiving operation is performed even in a state where If the light receiving operation is not performed unless the amount exceeds 50%, the southern part 22 is formed at a smaller angle than the notch 23. At this time, as the opening amount of the window section 25a through which the light receiving section 25 performs the light receiving operation becomes smaller, the angular region in which the tooth section 22 is formed becomes larger.

To give a specific example, for example, as shown in Figure 1,
The radius r from the rotation center 0 of the rotating disk 20 to the center of the window 25a is 17 mm, the width t of the window 25a is 0.5 mm, and the light receiving section 25 of the photointerrupter 21 is located at the window 25a.
If the light receiving operation is performed at an aperture ratio of approximately 20%,
As shown in FIG. 2, the forming angle area a of the tooth portion 22 is approximately 4
6° (therefore, the angular area where the notch 23 is formed is approximately 44°)
), a pulse signal output with a duty ratio of 50% was obtained from the light receiving section 25. This second figure is
The operating status of the light receiving section 25 at this time is schematically shown. The upper row shows the outer peripheral shape of the rotating disk 20 developed linearly, and the lower row shows the center of the window section 25a correspondingly. shows the relative position at which the light receiving unit 25 performs the light receiving operation (on) and stops the light receiving operation (off) and outputs the pulse signal.

Note that the upper and lower limits of the forming angle region of the tooth portion 22 are 45°.
If ±Δθ, then Δθ−360t/2πr. In the above example, the angle is Δθ-1.86', and even if the sensitivity of the light receiving section 25 is different, there is always an angle within this range at which an output signal with a duty ratio of 50% is obtained.

As described above, according to this embodiment, the light receiving section 25 of the photointerrupter 21 changes the tooth section 22 and the notch section 23 of the rotating disk 20 depending on the opening amount of the window section 25a to perform the light receiving operation. Since the formation angle regions a and b were changed from 1:1, it was possible to obtain a pulse signal output from the light receiving section 25 with a duty ratio of 50%. Therefore, the quality of the light-receiving element is improved, unlike the conventional case in which the 1 degree angle region between the tooth portion 2 and the notch portion 3 is fixed at a 1:1 ratio and each is mechanically formed at 45 degrees. Even when the output signal is required to be particularly precise due to circumstances such as miniaturization of the device or the like, it is possible to obtain a pulse signal output with an accurate duty ratio of 50%.

In particular, the effect is remarkable when used as a rotational position detection device for a variable reluctance morph as in this example.
Efficiency is improved by preventing generation of counter-torque 5 Torque ripples can be prevented, and the degree of freedom in motor design can be extremely high.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be implemented with appropriate modifications within the scope of the invention, for example, it can be applied to brushless motors and other devices equipped with rotating bodies other than motors. It is possible.

[Effects of the Invention] As is clear from the above description, according to the rotational position detection device for a rotating body of the present invention, the light receiving section has a window opening rate of 50.
If the light-receiving operation is performed even in a state where the aperture ratio is less than In cases where the light receiving operation is not performed unless the value of 50%
This has an excellent effect in that it is possible to obtain a pulse signal of .

[Brief explanation of the drawing]

Figures 1 to 4 show a large-scale embodiment of the present invention, with Figure 1 being a schematic front view of the main parts, and Figure 2 having an aperture ratio of approximately 20%.
Figure 3 is a longitudinal cross-sectional side view of the h1 variable reluctance motor, and Figure 4 schematically shows the rotor and stator of the nI & reluctance motor. FIG. FIG. 5 is a diagram corresponding to FIG. 1 showing a conventional example, and FIG. 6(a),
(b). (c) is a diagram corresponding to FIG. 2 showing a conventional example when the sensitivity of the light receiving section is intermediate, good, and bad, respectively. In addition, Fig. 7 is a characteristic diagram showing the relationship between the rotational position and torque of the variable reluctance morph depending on the rotor tooth width, and Fig. 8 is a characteristic diagram showing the relationship between the rotational position and torque of the variable reluctance motor depending on the stator tooth width. FIG. In the drawing, 11 is a variable reluctance motor, 15 is a rotor (rotating body), 19 is a rotational position detection device, 20 is a rotating disk, 21 is a photointerrupter, 22 is a tooth portion (light shielding portion), 2
3 is a notch (transparent part), 24 is a light projecting part, 25 is a light receiving part,
25a indicates a window portion.

Claims (1)

[Claims] 1. A rotating disk provided on a rotating body and having light shielding parts and transparent parts formed alternately in the circumferential direction, a light projecting part, and a light receiving part that receives light from the light projecting part through a window part. and a photointerrupter fixedly arranged with the rotating disk in between, and a photointerrupter with a duty ratio of 50 is provided from the light receiving section as the rotating body rotates.
% pulse signal, and if the light receiving section receives light even when the aperture ratio of the window is less than 50%, the light-shielding section of the rotating disk may be transmitted through the light-shielding section. If the light receiving part is formed in a larger formation angle area than the light part, and the light receiving part does not perform light receiving operation unless the aperture ratio of the window part exceeds 50%, the rotating disk A rotational position detecting device for a rotating body, characterized in that the light-shielding portion is formed in a smaller formation angle area than the light-transmitting portion.