JP2584122Y2 - Positioner - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioner suitable for application to an electropneumatic positioner or the like used in, for example, a drive control section of a pneumatic control valve, and more particularly to a zero point adjustment section and span adjustment of output pressure in this positioner. About the department.

[0002]

2. Description of the Related Art Conventionally, as a zero adjustment mechanism or a span adjustment mechanism in an electropneumatic positioner or the like used for drive control of a control valve, a mechanism using a spring for mechanical adjustment or a switch is used. There has been known a device which is electrically adjusted by using such a method.

[0003] Of these, the latter method of electrical adjustment is applied to, for example, an electropneumatic positioner having a pressure-resistant explosion-proof structure shown in FIG. In brief, the positioner 1 has a pressure-resistant explosion-proof device housing 2 in which a displacement detecting unit 5 such as a potentiometer for converting the displacement of an operating shaft 4 of a regulating valve 3 into an electric signal I1, and an input detecting device. , A control operation unit 6 having a CPU, etc., an electropneumatic converter 7, a nozzle flapper mechanism 8, a terminal board 21, and the like are housed and arranged. A span adjustment switch 9 and a zero point adjustment switch 11 are provided inside the housing 2. A span adjustment screw 10 for operating these switches 9 and 11 from the outside and a zero point adjustment switch are provided. A screw 12 is screwed into a wall of the housing 2.

When the input signal I 0 is supplied to the coil 13, the electro-pneumatic converter 7 causes the flapper 16 of the nozzle flapper mechanism 8 to be driven by the magnetic force of the coil 13 and the magnet 14. Fulcrum 15
And is converted into a pneumatic signal by a change in back pressure of the nozzle 17 caused by the displacement of the flapper 16. That is, the nozzle flapper mechanism 8 includes a flapper 16 that swings around the fulcrum 15,
A nozzle 17 is provided at one end of the flapper 16 so as to be close to and opposed to the supply air pressure Psup and is supplied from an air supply source via a pipe 18. The nozzle back pressure of the nozzle 17 is amplified by a pilot relay 19, and the output air pressure is increased. Pout
Is output to the drive device 20 of the regulating valve 3. Further, a pressure gauge 22 for supply air, a pressure reducing valve 23, a throttle 24 and an automatic / manual switching means 25 are provided in the middle of the pipe 18.

The pilot relay 19 belongs to a bleed type because a part of the supply air pressure Psup is constantly released to the atmosphere during a normal operation. The pilot relay 19 has two diaphragms 27A and 27B and a partition wall. The housing 28 is divided into four chambers by an air supply chamber 30, an output chamber 31, a bias chamber 32, and a nozzle back pressure chamber 33. Air supply chamber 30
Is supplied with supply air pressure Psup through the pipe 18.

The output chamber 31 is provided with the diaphragm 2
Piston 36 held at one end by 7A, 27B
The first and second chambers 31A and 31B are partitioned by an O-ring 37 fitted to the small-diameter portion at the lower end of. The first chamber 31A is connected to the air supply chamber 30 by a communication hole 38 provided in the partition wall 28 and controlled to be opened and closed by a poppet valve 39, and is connected to the driving device 20 of the adjustment valve 3 by a pipe 41. ing. On the other hand, the second chamber 31B communicates with the outside through the bleed hole 40.

A poppet valve 39 for controlling the opening and closing of the communication hole 38 penetrates the communication hole 38 so as to be able to move forward and backward, and is normally biased in the closing direction, that is, rightward in the drawing by a spring 42, so that the left end is normally turned. The communication hole 38 is closed.
The first chamber 31A and the second chamber 31B are connected to the piston 3
6 can be communicated with each other, but usually, one end opening of the communication hole 45 is closed by a poppet valve 39.

A supply air pressure Psup is supplied to the bias chamber 32 via a bias pipe 46 as a bias pressure PB. A nozzle back pressure PN is supplied to the nozzle back pressure chamber 33 through a pipe 47 as an input pressure. The piston 36 also serves as an area plate, and the nozzle back pressure PN acts on one end surface thereof, and the bias pressure PB and the spring 28 are opposed to the nozzle back pressure PN. In addition, 50 is a storage case for the pilot relay 19, 51 and 52 are flame arresters for nozzle back pressure and exhaust, 53 is a feedback lever, and 54 is a pressure gauge for output air.

[0009] The valve positioner 1 having such a configuration.
, The control valve 3 is maintained in the fully closed or fully opened state depending on the magnitude of the input signal I0. In the fully closed state of the control valve 3, the feedback lever 53 that rotates in conjunction with the operating shaft 4 is stopped at a position that has been rotated downward by a maximum angle. In this state, the electric signal I1 of the displacement detector 5 is equal to the input signal I0, is A / D converted, and is input to the control calculator 6 as a feedback signal. Since the input signal I0 and the feedback signal I1 input to the control operation unit 6 have the same value, the difference current is zero, and no correction signal is sent to the electropneumatic converter 7. When the input signal I0 changes in accordance with the set value and the control calculation unit 6 deviates from the feedback signal I1 from the displacement detection unit 5, a correction signal corresponding to the deviation is output to the electropneumatic converter 7.

The coil 13 and the magnet 14
When the flapper 16 is oscillated in the counterclockwise direction due to the magnetic action force of the above, the nozzle gap decreases. When the nozzle gap decreases, the nozzle back pressure PN increases, so that the output pressure Pout of the pilot relay 19 increases to operate the driving device 20. As a result, the operating shaft 4 moves upward to open the control valve 3. The movement of the operating shaft 4 is transmitted as a force for rotating and displacing the feedback lever 53 counterclockwise in the drawing. When the feedback lever 53 rotates, the current value of the electric signal I1 input as a feedback signal from the displacement detection unit 5 to the control calculation unit 6 gradually increases, and the current value of the electric signal I0 changes according to the set value. Is reduced, and the valve opening is stabilized when the difference current becomes zero. The operation of returning from the valve open state to the fully closed state operates in the reverse manner.

The pilot relay 19 operates so as to amplify the output pressure Pout to a required magnitude as the above-mentioned nozzle back pressure PN increases and decreases. This is well known and will not be described in detail. Omitted.

In the positioner 1 as described above, the zero point adjustment and the span adjustment can be performed from the outside of the housing 2 by rotating the zero point adjustment and the span adjustment screws 10 and 1.
The two microswitches provided as switches 9 and 11 for zero point adjustment and span adjustment in the housing 2 are selectively turned on and off by the cam at the inner end of the housing 2, and the control operation unit 6 and the like operate based on the signals. Processing is performed to perform zero point adjustment or span adjustment.

[0013]

However, in such a conventional zero point adjustment unit and span adjustment unit, the adjustment switches 9 and 11 comprising two micro switches are used.
, Adjustment screws 10 and 12 provided with cams, etc., their mounting parts, sealing parts, etc. are required.
There were problems such as troublesome manufacturing and assembly.

In particular, when the valve positioner 1 such as the above-described electro-pneumatic positioner is attached to a control valve 3 installed at a site such as an oil refinery, a flapper is mechanically operated based on an electrical input signal. It is necessary to house and arrange the control operation unit 6, the nozzle flapper mechanism, the electropneumatic converter 7 and the like for the purpose of the displacement in the housing 2 having the pressure-resistant explosion-proof structure. It is necessary to secure a clearance and clearance depth that meet the explosion-proof standards between the
There is a problem that the structure becomes complicated and processing accuracy is required.

For this reason, in the positioner 1 which employs a pressure-resistant explosion-proof structure used in an explosion-proof area, a pressure switch 60 as shown in FIG. And a pipe 61 for selectively supplying the supply air pressure Psup from the outside of the housing 2 to the frame arrestor 6 on the wall of the housing 2.
There is also known a configuration in which the switch 60 is turned on / off by air pressure to perform zero point adjustment or span adjustment through the air outlet 2 through the air passage 2. In the figure, 63 is a stop valve, 64 is a pipe having a throttle 64a and open to the atmosphere, and 65 is a switch signal detection circuit.

Further, as described above, as a zero-point adjusting section and a span adjusting section using a pressure switch, those having a structure as disclosed in Japanese Patent Application No. 2-31068 are also known.

However, in such a structure, in the example of FIG. 3, stability in operation is poor in terms of temperature characteristics of the pressure switch 60 and the like, particularly, temperature characteristics at a low temperature. Must be opened and closed each time, which is a problem in terms of operability. Further, there is a problem that the air circuit is complicated, and the flame arrester 62 is required to penetrate the housing 2 to meet the explosion-proof standards.

In the latter example, a special tool such as a hand-pump or an air cylinder is required to perform a zero point adjustment or a span adjustment as a special tool for turning on and off the pressure switch, which is troublesome and complicated. Operation was required, and there was also a problem in terms of reliability.

The present invention has been made in view of such circumstances, and the zero point adjustment and the span adjustment can be easily and appropriately performed by an extremely simple structure, and the stability in operation and the reliability of the adjustment accuracy are reliable. It is an object of the present invention to obtain an inexpensive positioner which is excellent in the above-mentioned conditions, requires no special jigs, and has sufficient countermeasures in the case of a flameproof type.

[0020]

In order to respond to such a demand, a positioner according to the present invention has a light shielding property in which a nozzle flapper mechanism, a pilot relay, an electropneumatic converter, a feedback section, an electric apparatus section and the like are provided. At least a pair of light-transmitting glass windows and a light-shielding cover for selectively covering the glass windows are provided on a part of the housing having a zero-point adjustment circuit and a span adjustment circuit at a portion facing the glass windows in the housing. The photoelectric element is connected to any one of the above, and the photoelectric element is operated by opening and closing a light shielding cover so as to allow external light to enter the housing through the glass window. Is performed.

[0021]

According to the present invention, the light-shielding cover is selectively opened and closed outside the positioner housing, and external light is incident or blocked into the housing through the glass window. By operating the photoelectric element to change the resistance value or the like, the zero point adjustment and the span adjustment can be performed in a required state from outside the housing.

In particular, according to the present invention, in the case of the explosion-proof type, the space between the opening of the housing and the glass window may be configured so as to satisfy the explosion-proof standard, and the safety and reliability are excellent. By turning the element on and off by using external light or the like by opening and closing the glass window and the light shielding cover without using a special adjustment jig or the like, zero point adjustment or span adjustment can be performed in a required state.

[0023]

FIG. 1 shows an embodiment of a positioner according to the present invention. In this embodiment, only the main structure of a pressure-resistant explosion-proof electropneumatic positioner is shown. In the drawings, parts corresponding to those in FIGS. 2 and 3 are denoted by the same reference numerals.

According to the present invention, as described above, the opening 71 is provided in a part of the light-shielding housing 2 in which the nozzle flapper mechanism, the pilot relay, the electropneumatic converter, the feedback section, the electric equipment section and the like are provided. And a light-shielding cover 73 for selectively covering at least a pair of light-transmitting (light-transmitting) glass windows 71 is provided, and a portion facing the glass window 72 in the housing 2 is provided with a zero. A photoelectric element 70 such as a photo-resistive element such as CdS connected to a switch signal detection circuit 65 serving as a point adjustment circuit and a span adjustment circuit is provided, and external light (such as an external light source 74 or natural light) is passed through the glass window 72. The photoelectric element 70 is actuated by opening and closing the light-shielding cover 73 so that the light enters the housing 2. Is characterized in was configured to perform.

Here, the glass window 72 is provided in the opening 71 of the housing 2 with a gap conforming to the explosion-proof standard and a depth of the gap, and is configured as a flameproof structure. The light-shielding cover 73 is rotatably supported at one end thereof on the side edge of the opening in the housing 2 via a pivotal support portion 73a, and is selectively opened and closed as needed.

In such a configuration, the light-shielding cover 73 is selectively opened and closed outside the housing 2 of the positioner 1 so that the external light 74 enters or shuts out of the housing 2 through the glass window 72. By operating the photoelectric element 70 such as a photoresistive element to change the resistance value or the like, the zero point adjustment and the span adjustment can be easily and reliably performed in a required state from outside the housing 2.

In particular, according to the present invention, in the case of a flameproof type, it is possible to obtain a flameproof structure only by configuring the space between the opening 71 of the housing 2 and the glass window 72 so as to satisfy the flameproof standard. It is excellent in safety and reliability, and uses the outside light 74 or the like in the photoelectric element 70 and shields the glass window 72 from light without using a special adjustment jig such as a conventional pressure supply unit. Zero point adjustment or span adjustment by turning on and off by opening and closing the cover 73 can be performed.

Therefore, according to such a configuration, the structure of the zero point adjusting unit and the span adjusting unit can be simply and easily configured, and the operation is only required to open and close the light shielding cover 73. Can be performed reliably and with high reliability. In the daytime, natural light such as sunlight can be turned on / off sufficiently, and in the nighttime, external lighting means or a flashlight carried by maintenance personnel may be used, and the advantages are clear.

The present invention is not limited to the structure of the embodiment described above, and it goes without saying that the shape, structure and the like of each part of the positioner 1 can be appropriately modified and changed. For example, in the above-described embodiment, the case where a photoresistive element is used as the photoelectric element 70 has been described. However, it is sufficient that an on / off signal can be obtained by sensing light, such as a phototransistor, a photodiode, and the like. It is free to use various types of photoelectric elements.

Further, in the above-described embodiment, the description has been made for zero point adjustment or span adjustment. However, the present invention may be applied to any of the adjusting units, or may be applied to only one of the adjusting units. Needless to say.

[0031]

As described above, according to the positioner of the present invention, at least a pair of light-transmitting glass windows and a pair of light-transmitting glass windows are provided in a part of the light-shielding housing in which the electropneumatic converter and the like are provided. A light-shielding cover for selectively covering the glass window is provided, and a photoelectric element connected to one of a zero-point adjustment circuit and a span adjustment circuit is provided in a portion facing the glass window in the housing; Opening and closing the light-shielding cover to allow external light to enter the housing through the photoelectric element is activated, and either zero point adjustment or span adjustment is performed, so despite the simple and inexpensive configuration, It has the following excellent effects.

The light-shielding cover is selectively opened and closed outside the housing of the positioner, and external light enters or shuts out of the housing through the glass window, whereby a photoelectric element such as a photo-resistive element is operated by turning on and off, thereby controlling a resistance value and the like. By varying, the zero point adjustment and the span adjustment can be easily and reliably performed in a required state from outside the housing.

In the case of a pressure-resistant explosion-proof type positioner used in an explosion-proof area, the space between the opening of the housing and the glass window may be configured so as to satisfy the explosion-proof standard, which is excellent in safety and reliability. .

Since the photoelectric element which is turned on and off by external light or the like is skillfully used, the photoelectric element is simply turned on and off by opening and closing the glass window and the light shielding cover without using a special adjustment jig or the like. Zero point adjustment or span adjustment can be performed as required.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a positioner according to the present invention and showing a main configuration for performing zero point adjustment and span adjustment.

FIG. 2 is a schematic sectional view showing a conventional example of an electropneumatic positioner suitable for applying the present invention.

FIG. 3 is a schematic diagram showing another example of a conventional zero point adjustment unit or span adjustment unit.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electropneumatic positioner 2 equipment housing with explosion-proof construction 3 regulator valve 6 control operation unit 7 electropneumatic converter 8 nozzle flapper mechanism 65 switch signal detection circuit 70 photoelectric element 71 opening 72 translucent glass window 73 light shielding cover 74 external light source Psup Supply air pressure Pout Output pressure PN Nozzle back pressure

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F15B 9/07 F16K 31/128 G05D 3/00 G05D 3/12

Claims (1)

(57) [Scope of request for utility model registration] 1. A positioner having a nozzle flapper mechanism, a pilot relay, an electro-pneumatic converter, a feedback unit, an electric device unit, and the like in a housing, wherein at least a pair of light-transmitting glasses is provided in a part of the light-shielding housing. A window and a light-shielding cover for selectively covering the glass window are provided, and a part facing the glass window in the housing is provided with a photoelectric element connected to one of a zero-point adjustment circuit and a span adjustment circuit, and By opening and closing the light-shielding cover so as to allow external light to enter the housing through the glass window, the photoelectric element is operated to perform any one of zero point adjustment and span adjustment. And positioner.