JPH0419402A - Positioner - Google Patents

Abstract

PURPOSE:To suppress the influence of the vibration of a piping system to improve the vibrationproofness by feedback-supplying the electric signal which is obtained by the conversion of the displacement quantity of the working shaft of a driving device which is arranged separately from a positioner to a control calculation part, and transmitting the difference between this signal and the input to the positioner to an electricity-air conversion part. CONSTITUTION:The displacement of a working shaft which is detected mechanically is converted to the electric signal by a displacement detection part 31 and inputted into an A/D conversion part 46, together with the signal of an input electric current detection part 45 for detecting the input signal to a valve positioner, and inputted as the A/D converted feedback signal into a control calculation part 47. Further, an electricity-air conversion part 48 is constituted of a magnet unit, nozzle flapper mechanism, and a pilot relay, and when the input signal is varied according to a set value, and a difference from a displacement detection part 31 is generated, the correction signal of the control calculation part 47 is received to drive a driving device 3. Accordingly, the need of directly installing the positioner to the driving device 3 is obviated, and the influence of the vibration of a piping system is suppressed, the vibrationproofness is improved, and the installation work and adjusting work can be carried out easily in simple manners.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is used to control the operating shaft of an automatic aS moderation valve used in various plants such as petrochemical and chemical industries to a position according to an input signal. The present invention relates to a positioner suitable for application to valve positioners and the like.

[Prior Art] Conventionally, a positioner for an automatic control valve is attached to the yoke of a drive device, and mechanically feeds back the displacement of the operating shaft using a lever or the like, thereby controlling the relationship between the instrument signal and the valve shaft position against external disturbances. It is controlled to keep it accurate at all times. Figure 3 shows a conventional example of such a valve positioner. The attached pneumatic drive device 5 is a valve positioner screwed to one side of the yoke 4 via a bracket or the like, and this valve positioner 5 swings from its housing 8 toward the operating shaft 2. It has a feedback lever 7 which constitutes the feedback mechanism 6 and is freely extended.The inner end of the feedback lever 7 is rotatably supported by a shaft A, and the outer end is supported by a long hole 9 and a pin 10. It is connected to the operating shaft 2. Further, the valve positioner 5 has a built-in nozzle flapper mechanism 11, and receives an input signal r. (for example, 4 to 20 mA) is converted into a displacement of the magnet 14 by the magnet unit 13 and transmitted to the flapper beam 12 via the connector 15. Since the beam 12 swings around its fulcrum 16, the flapper When the back pressure of the nozzle 17 arranged close to and facing the beam 12 changes, and this nozzle back pressure is amplified by the pilot relay 18 and outputted as a valve drive force and transmitted to the drive device 3, the drive device 3 is driven. The actuating shaft 2 is displaced in the vertical direction, thereby adjusting the valve opening degree of the automatic control valve 1. Further, the effect of the operating shaft 2 is received by the feedback lever 7 and fed back to the nozzle flapper mechanism 11, thereby stabilizing the movement of the flapper beam 12.

The terminal box 20 of the magnet unit 13 is a pressure gauge, 21 is a pressure reducing valve, 22 is a feedback spring, and 23 is a zero adjustment spring.

[What the invention tries to solve! By the way, the IIF valve 1 constitutes a dynamic source that generates vibrations as the flow rate is controlled. On the other hand, the valve positioner 5 is attached to the outside away from the central axis of the drive device 3 due to the structure of the drive device 3. Therefore, they are easily affected by piping vibrations during plant operation, and when resonance occurs, there are problems such as disconnection of the coils of electrical components, wear of the flapper beam 12 due to vibration, and even mechanical damage due to wear in a short period of time. Ta. That is, the flapper beam 12
When the nozzle vibrates in resonance with the automatic control valve 1 and repeatedly collides with the nozzle 17 at a fast cycle, this contact portion is worn out, changing the nozzle gap, and in the case of tympania, a hole is formed due to fatigue.

Further, there is a problem in that malfunctions such as hunting and drifting occur even if damage does not occur.

Therefore, the present invention has been devised in view of the above-mentioned problems in the conventional piping system, and it improves vibration resistance without being affected by the vibration of the piping system caused by plant operation, and also simplifies installation and adjustment work. The purpose is to provide a value and easy positioner.

Means for Solving the Problem] In order to achieve the above object, the present invention comprises an input current detection section,
Drive a positioner equipped with a control calculation section with a CPU and an electro-pneumatic conversion section! It is installed separately from the 1F device, converts the amount of displacement of the operating shaft of the drive device into an electric signal by a converter, feeds the electric signal back to the control calculation section, and inputs this feedback signal and an input signal to the positioner. and the difference is retransmitted to the electro-pneumatic converter.

[Function] In the present invention, the positioner is placed separately from the drive device, the displacement of the operating shaft of the drive device is converted into an electric signal by a converter, and this electric signal is transmitted to the C of the control calculation section provided in the positioner.
Feedback to PU.

The CPU controls the input signal and the feedback signal to match by comparing the input signal and the feedback signal and retransmitting the difference to the electro-pneumatic conversion section.

[Example J] Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIG. 1 is a configuration diagram showing an actual example of a positioner according to the present invention. Components and the like that are the same as those in FIG. 3 are designated by the same reference numerals, and their explanations will be omitted. In the figure, 3o is a mounting plate, and 31 is a displacement detection section of the operating shaft 2.

The mounting plate 30 is attached to the yoke 4 of the control valve 1 in the left-right direction, that is, in the operating direction of the operating shaft 2, by means of a pair of upper and lower elongated holes 32 and a set screw 33 inserted through the elongated holes 32.
It is housed so that it can be moved and adjusted in a direction perpendicular to the .

The displacement detection section 31 is composed of a lever 34 that mechanically detects the displacement of one operating shaft 2, and a variable #ll 335 that converts the amount of rotation of the lever 34 into an electrical signal. Lever 34
is disposed on the storage plate 30 with its base end supported vertically by a shaft 36, and its free end is connected to the operating shaft 2 through a long hole 9 and a pin 10. has been done. Therefore, when the operating shaft 2 is displaced in the vertical direction,
The lever 34 is rotated vertically about the shaft 36 by an angle corresponding to the amount of displacement of the operating shaft 2.

In this embodiment, the converter 35 is composed of a linear potentiometer arranged near the base of the lever 34 so as to be substantially orthogonal to the lever, and includes a resistor 37 connected to a power source (not shown), and a resistor 37 connected to a power supply (not shown). Long hole 38 provided on the base side of 34
a movable contact 39 that is slidably held by the resistor 37 and changes the resistance value by sliding along the resistor 37;
It is configured to feed back a voltage change accompanying a resistance value change to the valve positioner 5 as an output signal.

The valve positioner 5 does not have a conventional mechanical feedback mechanism, and therefore the control valve 1
It is placed separately from the yoke 4, that is, mechanically separated from the yoke 4, and placed at an appropriate location that is not subject to vibration.

FIG. 2 is a block diagram showing the electric circuit of the valve positioner 5 and the drive unit W3, and 45 is an input signal (■) to the valve positioner 5. An input current detection section 46 detects the electric signal o from the input current detection section 45 and the displacement detection section 3.
an A/D conversion unit that A/D converts the electrical signal I2 from 1;
47 is a control calculation unit including a CPU (central processing unit W); 48
is the electro-pneumatic converter. The control calculation unit 47 includes the displacement detection unit 3
When the electric signal ■2 is fed back from the valve positioner 1, this electric signal ■2 and the input signal I to the valve positioner 5 are
The difference signal is re-sent to the electro-pneumatic converter 48.

The electro-pneumatic converter 48 is composed of a magnet unit 13, a nozzle flapper mechanism 11, and a pilot relay 18 shown in FIG. In FIG. 1, reference numeral 50 denotes a leaf spring that supports approximately the center of the flapper beam 12.
One end of 0 is fixed to the flapper beam 12 with a set screw 51, and the other end is fixed to a bridge 52 fixedly arranged on the magnet unit 1B11@, and both of these fixed parts have a bent portion bent into a substantially hook shape. A corner is provided, one corner of which forms an effective fulcrum 16. 53 is a stopper 55a for regulating the rotation of the flapper beam 12, 55b is a span adjustment switch, 56 is a span adjustment screw, 57
a, 57b are photographic switches, 58 are photographic switches, 59
is a printed circuit board of the electric circuit shown in FIG.

It should be noted that the flapper mechanism 11, magnet unit 13, pilot relay 18, etc. are conventionally well known, and therefore further detailed explanation will be omitted.

Next, the operation of the valve positioner 5 having such a configuration will be explained.

The human power signal ■o to the valve positioner 5 is, for example, 4 mA.
When the current is 4 mA, the automatic control valve 1 is kept fully closed, and when the current is 20 mA, the automatic control valve 1 is kept fully open. When the automatic control valve 1 is in the fully closed state, the lever 34 is at the maximum downward rotation position, that is, the first position.
It is stopped at the position indicated by the two-point fli line in the figure. The movable contact 39 of the potentiometer 35 is located below the resistor 37, and the electrical signal 2 of the potentiometer 35 at this time is the input signal 2. It is A/D converted by the A/D converter 46 and inputted to the mal calculation unit 47 as a feedback signal. Input signal ■ input to the control calculation unit 47. Since the electric signal (2) and the electric signal (2) have the same value, the voltage difference therebetween is zero, and no correction signal is sent to the electro-pneumatic converter 48.

In this state, the input signal ■. changes in accordance with the set value, and if a deviation occurs in the control calculation unit 47 via the A/D conversion unit 46 from the electric signal 2 from the displacement detection unit 31, a corresponding correction signal is sent to the electro-pneumatic conversion unit 48. As a result, the output air pressure changes to P O11t, causing the drive device 3 to operate.

As a result, the operating shaft 2 moves upward and engages the automatic control valve 1. Further, the movement of the actuating shaft 2 is transmitted as a force that rotationally displaces the lever 34 in the counterclockwise direction in FIG. Lever 34
When rotates, the movable contact 37 of the potentiometer 35 moves upward, so the voltage value of the electric signal 2 inputted as a feedback signal from the displacement detection section 31 to the control calculation section 47 gradually increases, and the setting Input signal according to the value. The difference between the voltage value and the voltage value decreases, and the valve tightness becomes stable when this voltage difference becomes zero.

Note that since the operation of returning the valve from the open state to the fully closed state is the opposite to the above, the explanation thereof will be omitted.

In the valve positioner 5 having such a configuration, the mechanical displacement of the actuating shaft 2 is converted into an electrical signal and fed back to the valve positioner 5, so the positioner 5 and the displacement detection section 31 can be connected by a code. There is no need to fix the positioner 5 itself to the yoke 4 of the control valve 1 by simply electrically connecting it, and it can be placed separately from the control valve 1. Therefore, the vibration of the control valve 1 is not picked up, and the reliability and durability of the valve positioner 5 are improved.

In addition, although the above-mentioned example explained the case where a linear type potentiometer was used as the converter 35, the present invention is not limited to this, and it goes without saying that a rotary type potentiometer may be used.

In that case, the movable contact 39 may be attached to the lever 34 and the rotation shaft 36.

[Effects of the Invention] As explained above, the positioner according to the present invention includes an input current detection section, a control section having a CPU, and an electro-pneumatic conversion section, and converts the displacement of the operating shaft into a converter. Since the positioner is configured to be converted into an electrical signal by the controller, this electrical signal is fed back to the control calculation unit, and the deviation between the input signal and the feedback signal is detected, it is not necessary to directly connect the positioner to the drive device that makes up the vibration system. Since the installation location can be freely selected, it is not affected by piping system vibration, prevents malfunctions such as flapper hunting and drift, and prevents wear and damage, improving the reliability and vibration resistance of the positioner. let In addition, since the CPU is used for calculation processing, the positioner can perform PID @ operation (proportional-integral-differential operation), and if the positioner can be installed separately from the drive device, installation and adjustment work will be easier. Simple and easy.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of a positioner that is damaged by the present invention, Fig. 2 is a block diagram showing an electric circuit of the positioner and drive device, and Fig. 3 is a schematic block diagram showing a conventional example of a valve body 3. It is. DESCRIPTION OF SYMBOLS 1... Automatic control valve, 2... Operating shaft, 3... Drive device, 4...- Yoke, 5-- Valve positioner, 7...
...Feedback lever, one to one nozzle flapper mechanism, 12...-flapper beam, 13... Magnet unit, 14... Magnet, 15... Connector,
18...Pilot relay, 30...Mounting plate, 31
・-・Displacement detecting section, 34...-lever, 35... Potentiometer, 45... Input current detecting section, 46...
A/D conversion section, 47... control calculation section, 48... electro-pneumatic conversion section. Patent applicant Yamatake Honeywell Co., Ltd.

Claims (1)

[Claims] A positioner including an input current detection section, a control calculation section having a CPU, and an electro-pneumatic conversion section is installed separately from the drive device, and a converter converts the amount of displacement of the operating axis of the drive device into an electric signal. A positioner characterized in that an electrical signal is fed back to the control calculation section, this feedback signal is compared with an input signal to the positioner, and the difference is retransmitted to the electro-pneumatic conversion section.