JPH02248780A - Valve control device equipped with rotary encoder - Google Patents

Abstract

PURPOSE:To enhance the accuracy of the above device by correctively developping the bit pattern of a rotary plate so that the relation between the intrinsec property and rate of opening of the valve becomes a desired control property, and integrating a rotary encoder into a valve driving electric motor shaft, the rotary encoder detecting the bit pattern by means of light emitting and receiving elements via a slit plate. CONSTITUTION:A rotary encoder 20 comprises a rotary plate A having a bit pattern and fixed to the rotary shaft E of an electric motor EM2, and a base B with a light emitting element (a), a slit plate D and a base C with a light receiving element (b), all of which are arranged in such a manner as sandwiching the rotary plate A and which are stored in a box body G via a bearing F. The bit pattern is correctively developped so that the relation between the flow rate property and rate of opening of a valve 1 becomes e.g. a linear property, and the pattern is formed as a translucent hole (black portion), and light from the light emitting element (a) is received by the light receiving element (b) through the bit pattern and the slit plate D and is compared with a control signal 7 by means of a microcomputer 22 via a billet convertor 21, and, in accordance with its deviation, the rate of opening of the valve 1 is feedback-controlled via a relay 25 and the electric motor 2. It is thus made possible to enhance the control accuracy and response speed of the valve control device.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides a rotary encoder having a specially processed bit pattern as a sensor for valve opening correction or positioning correction of a rotary valve such as a butterfly valve. The present invention relates to a valve control device 1.

[Conventional technology]

Conventionally, when controlling a butterfly valve, which is a rotary valve, with desired flow characteristics, as shown in FIG. 4 is electrically detected by the current changer 5 and converted to the valve opening degree, and this is corrected by the correction circuit 6 so that the Cv value and the valve opening degree have a linear proportional relationship. The proportional valve opening is input as a signal 7, compared 8 with the corrected value including the valve characteristic Cv, and the valve 1 is operated until the valve opening allows the desired flow.

The desired flow characteristics were obtained.

In addition, the above Cv value refers to fresh water of 6G"F (15.6℃).

The differential pressure between the front and rear is 1 psi (0.07 kgflsJ)
The flow rate is expressed in US gan/win when maintained at

Here, Q: flow rate Bo/h ΔP; pressure before and after the valve kd/al G: ratio (in the case of water = 1) [Problem to be solved by the invention] However, the above conventional system has the following problems. There were some problems.

(1) As shown in the control flow diagram of FIG. 4, the conventional type is composed of an analog electric circuit, so high precision is required, and the adjustment of the electric circuit is complicated and expensive.

(i) An arithmetic circuit is required for input signals and valve opening degree correction 6.

(i) Since many potentiometers 3 are sliding type, their mechanical lifespan is short and their environmental resistance is poor.

(Noodles) As shown in FIG. 5, a microcomputer 10 is used in the comparison calculation circuit, but this also basically uses a potentiometer 3 as a valve position detector, so analog.

The reliability of both digital circuit converters 11 and 12 is poor, and therefore, for practical use, a protection circuit (not shown) must be provided, resulting in an increase in cost.

SUMMARY OF THE INVENTION An object of the present invention is to provide a valve control device that corrects the valve opening degree or positioning, which has a simple circuit configuration and is capable of digital processing.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a rotary plate (A) having a bit pattern in which the characteristic valve characteristic and the valve opening degree are developed and corrected to the desired control characteristic, and a rotary plate (A) arranged at a position corresponding to each beat. a substrate (B) incorporating a light-emitting element;
A substrate (C
) and a slit plate (D) for accurate beat detection
, a rotating shaft (E) disposed at the center of the rotating plate (A) and driving the rotating plate, and a bearing (F) that pivotally supports the rotating shaft (E).
and a box body (G) containing these components is incorporated into the valve drive motor shaft.

The rotary encoder is constructed by specially processing the bit pattern of an absolute rotary encoder so as to correct the positioning of the valve drive section.

[For production]

Since the rotary encoder is configured as described above, the bit pattern of the rotary encoder is set so that the control characteristic of the valve indicating the relationship between the Cv value of the valve and the valve opening degree becomes a desired characteristic, that is, the characteristic valve characteristic Cv A linear characteristic where the relationship between the value and the valve opening is a linear proportional relationship of 45 degrees, an equal percentage characteristic where the relationship is proportional to the valve opening and the input signal, or a quick open that opens the valve opening rapidly. Each is developed and corrected to show its characteristics.

Therefore, when the valve is operated, a valve opening proportional to the desired flow rate flowing through the pipe (for example, if the flow rate is 172, the valve opening = 1/2) is input as a set value by signal 7, while the valve opening is A microcomputer or comparator compares the valve opening signal indicating the current opening indicated by the development-corrected bit pattern of the rotary encoder built into the drive motor shaft, and operates the valve to the desired valve opening. However, as described above, the bit pattern has been corrected to match the desired control characteristics of the valve, so for example, when the bit pattern has been corrected to have a linear characteristic, the flow rate proportional to the valve opening ( Cv value) will be obtained.

〔Example〕

FIG. 1 is a partial sectional view of a rotary encoder showing an embodiment of the present invention.

In the figure, A is a rotating plate, and the rotating plate A has a bit pattern as shown in the enlarged plan view of FIG. A board B is mounted stationary at a position corresponding to the rotary plate A, and a light emitting element a is mounted on the board B at a position corresponding to each bit. In addition, the rotating plate A
On the opposite side of substrate B (right side in the figure), there is one light emitting element a.
A substrate C incorporating a light-receiving element that receives light emitted from
is mounted stationary, and these rotary plate A and substrate C
A slit plate provided with slits is fixedly mounted between the two and the slit plates to ensure accurate bit detection. The rotating shaft E is supported by a bearing F, which is housed in a box G, and the shaft E is connected to an electric shaft for driving a valve body (not shown).

FIG. 2 is an enlarged plan view of the rotary plate A, and the black portions in the figure indicate through holes.As shown in the figure, a bit pattern developed and corrected to a desired control characteristic is formed by special processing. This device is usually formed into an absolute type that detects absolute position.

The above-mentioned special processing is, for example, when the flow rate characteristic (Cv-opening curve) of a valve is expressed by one equation using an approximate curve using a polynomial, and when this equation is changed to a recognized curve,
A polynomial approximation program using the least squares method is used.

Finally, a curve obtained by correcting the (Cv-opening degree) curve is obtained, and the curve is developed into bits to create an encoder pattern.

The bit pattern model shown in FIG. 2 is a simple increasing (or decreasing) curve that is converted into binary numbers and reflected in the bit pattern. Since the curves are used as bit patterns in this way, patterns on the same circle can have various widths (arc lengths) (conventional patterns are formed with patterns of the same width). is a subdivision of this curve into 1/28 (= 1/256), and the index in this case indicates the number of circles,
The higher the number, the higher the accuracy.

FIG. 3 is a control flow diagram of a valve control device in which the above-mentioned rotary encoder 20 is incorporated into the shaft of the electric motor 2 that drives the valve body 1, and the reference numerals shown in FIG. 4 and FIG. The same reference numerals as in the above shall indicate the same or similar parts.

In the figure, a rotary encoder 20 is built into the shaft of an electric motor 2 that drives a valve 1, and the rotary encoder 20 has a bit pattern that is developed and corrected to have one of the desired control characteristics, for example, a linear characteristic. Because I am doing
The opening degree of the valve 1 is bit-converted by the rotary encoder 20 and the bit converter 21, and the valve opening degree converted according to the control characteristics formed in the bit pattern is input to the microcomputer 22 as the current state. To be carried away.

On the other hand, the valve opening proportional to the desired flow rate (when the flow rate is 1/2, the valve opening is 172) is set as a set value to the voltage converter 23, A/D converter, or bit converter 24 by the signal 7. ,
After that, it is input to the microcomputer 22.

Then, the set value input ◎ is compared with the current value input above, and the operating current is adjusted as shown by the arrow through the relay 25 so that the valve opening corresponds to the input ◎. The flow is inputted to the electric motor 2, and the valve opening degree is adjusted to provide the desired flow rate of the valve 1.

According to this embodiment, by using a rotary encoder, the following effects can be achieved compared to the conventional technology.

(+) Even with conventional potentiometers,
If the resistance value can be set arbitrarily, desired control characteristics can be provided, but in this case, ultra-precision manufacturing is required, the cost is high, and the reference point is unknown. On the other hand, the accuracy of the bit pattern according to the present invention can be easily increased because it is sufficient to increase the number of bits.

0) Even in terms of response speed, conventional potentiometers have R/
The encoder of the present invention operates at high speed, although it is slow due to the use of an I (resistance/current) converter.

Furthermore, since the encoder is a digital circuit, it is resistant to voltage fluctuations and noise, and since it is non-contact, it has a long life and is highly reliable.

(i) Electric motors can be corrected using a microcomputer.

Conversion, correction, etc. can be performed using a data table, and operation is easy.

(Value) Even compared to the cam of a conventional positioner, the cam is mechanically controlled by the balance of a spring, so the correction range is narrow and the response speed is also limited, making it considerably slow. Further, the cam has no reference point due to its structure, whereas the encoder of the present invention has no mechanical sliding parts and has a fast response speed.

(Ma) In the present invention, by specially processing the bit pattern of the encoder, there is no restriction on the correction range of signal 1 positioning correction, and positioning control that takes advantage of the encoder becomes possible.

In addition, since it basically outputs a bit signal, it can be connected to a computer at low cost, and the advantages of digital signals can be utilized as is.

In addition, in the above-mentioned embodiment, an example was explained in which a linear characteristic in which the Cv value and the valve opening are in a linearly proportional relationship was adopted as the desired control characteristic, but a relationship in which the valve opening and the input signal are proportional is adopted. In the case of the equal % characteristic that causes the valve to open quickly, or the quick open characteristic that causes the valve to open quickly at the initial stage, the bit pattern of the rotary encoder can be formed to match each of the above characteristics, so that it is almost the same as in the above embodiment. In addition, the valve can be operated according to desired valve control characteristics.

Furthermore, although a structure in which a rotary encoder is attached to the valve drive motor shaft has been described, it is also possible to apply the structure to a structure in which the valve is driven by an air cylinder instead of an electric motor. In this case, instead of the rotation of the motor shaft, the linear reciprocating motion of the piston of the air cylinder is transmitted via the yoke to the valve shaft, and instead of controlling the operating current to the motor, the compression to the air cylinder is Air volume is controlled.

〔Effect of the invention〕

As explained above, according to the present invention, there is provided a rotary plate having a bit pattern in which specific valve characteristics and valve opening degree are developed and corrected to desired control characteristics, a substrate incorporating a light emitting element, and a light receiving element incorporated. By incorporating a rotary encoder consisting of a base plate and a slit plate into the valve drive shaft, the following effects can be achieved.

1) It is easy to increase the accuracy by increasing the number of bits, and the response speed is also fast.

(Lid) Since the encoder is a digital circuit, it is resistant to voltage fluctuations and noise, and since it is non-contact, it has a long life and is highly reliable.

(i) By specially processing the bit pattern of the encoder, there are no limitations on the correction range of signal/positioning correction, and positioning control that takes advantage of the encoder's advantages becomes possible.

Since it outputs a ('W) bit signal, it can be connected to a computer at low cost, and the advantages of digital signals can be used as is. Furthermore, since the electric motor can be corrected using a microcomputer, conversion and correction can be performed using a data table, making operation easy.

[Brief explanation of drawings]

Fig. 1 is a partially sectional side view of a rotary encoder showing an embodiment of the present invention, Fig. 2 is an enlarged plan view of a rotary plate having a bit pattern, and Fig. 3 is a valve incorporating the rotary encoder of the present invention. Control flow diagram of the control device, FIGS. 4 and 5 are control flow diagrams showing a conventional example. ■...Valve, 2...Electric motor, 7.
...Signal, 20...Rotary encoder, 21...
Bit converter. 22...Microcomputer, 23...Voltage converter, 24...
・A/D converter, bit converter, A... rotating plate,
B, C... Substrate, E... Rotating shaft, F... Bearing, a... Light emitting element, b... Light receiving element. 25...Relay D...Slit plate, G...Box, Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Scope of Claims] 1. A rotary plate (A) having a bit pattern in which specific valve characteristics and valve opening degree are developed and corrected to desired control characteristics, and light emitting elements arranged at positions corresponding to each beat are assembled. board (B)
, a substrate (C) incorporating a light-receiving element disposed opposite to the substrate (B), a slit plate (D) for accurate beat detection, and the center of the rotating plate (A). A rotary encoder consisting of a rotating shaft (E) disposed in the rotary plate and driving the rotating plate, a bearing (F) supporting the rotating shaft (E), and a box body (G) containing these, A valve control device equipped with a rotary encoder, characterized in that it is incorporated into a valve drive motor shaft. 2. A valve control device using a rotary encoder according to claim 1, wherein the rotary encoder is constructed by specially processing the bit pattern of the rotary encoder so as to correct the positioning of the valve driving section.