EP0120035A1 - Valve converter/positioner with remote feedback and memory - Google Patents
Valve converter/positioner with remote feedback and memoryInfo
- Publication number
- EP0120035A1 EP0120035A1 EP83902847A EP83902847A EP0120035A1 EP 0120035 A1 EP0120035 A1 EP 0120035A1 EP 83902847 A EP83902847 A EP 83902847A EP 83902847 A EP83902847 A EP 83902847A EP 0120035 A1 EP0120035 A1 EP 0120035A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- valve
- signal
- control signal
- condition
- set forth
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K3/00—Gate valves or sliding valves, i.e. cut-off apparatus with closing members having a sliding movement along the seat for opening and closing
- F16K3/02—Gate valves or sliding valves, i.e. cut-off apparatus with closing members having a sliding movement along the seat for opening and closing with flat sealing faces; Packings therefor
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D3/00—Control of position or direction
- G05D3/12—Control of position or direction using feedback
Definitions
- Valve converter/positioner with remote feedback and memory
- the present invention relates in general to appara- tus for effecting accurate positioning of valves, and in particular to such apparatus which provide, remotely available indication of true valve position.
- valves ar.e used to regulate the flow of pro- cess fluids. Proper operation of these valves is an important factor in achieving the formulation of a product within specifications, as well as in an effi ⁇ cient manner. Conceivably in potentially explosive processes, it also could mean the difference between a safe and an unsafe operating condition.
- Valve positioning mechanisms To facilitate accurate operation, a variety of valve positioning mechanisms have been used extensively in the past. Their basic operating principle is to maintain an energizing signal into a valve actuator until feedback provided from the valve itself, indica ⁇ ting that it has attained the desired position, termi ⁇ nates the energizing signal.
- Valve positioning mechanisms are of two basic types: the positioner, in which the feedback is provided by a mechanical linkage to the valve stem, and the converter, in which the feedback information is conveyed by either the pneuma ⁇ tic pressure or the electric current present at the valve actuator, depending on the type of actuator used. Both of these mechanisms are intended to ensure that the valve reaches the appropriate setting, despite friction in the actuator or in the valve stem packing.
- the communication between a remotely- located controller and the valve positioning mechanism is typically one-way. That is, although the controller emits a command signal to the positioning mechanism, there is no confirmation at the controller that the valve has assumed the desired setting.
- local feedback exists between the valve and its actuator, as describex_L__above, there has not been available an effi ⁇ cient means for providing feedback to the rem ⁇ tely located controller.
- the human operator may need positive indication of actual valve position to reliably and safely regulate the process. Often, the only way the operator is made aware of an improperly set valve is by the response of the process itself.
- auxiliary devices for indicating valve position.
- One such device is a po- tentiometer, in which the wiper arm is attached to the valve stem. A constant voltage input is maintained across the total resistance of the potentiometer, while the movements of the wiper arm change the output signal in proportion to the valve position.
- a po- tentiometer in which the wiper arm is attached to the valve stem.
- a constant voltage input is maintained across the total resistance of the potentiometer, while the movements of the wiper arm change the output signal in proportion to the valve position.
- OMPI such as television monitors, for viewing the position of the valve.
- valve positioning mechanism there also- exists a need for the valve positioning mechanism to have a memory, i.e., to be able to hold a valve in a preset position in the event of loss of power to the positioning mechanism, and yet do so at sufficiently low energy levels to avoid ignition of
- the present invention operates in the context of a valve positioning mechanism of the type in which a valve actuator located within a process environment moves the valve stem in accordance with a command signal generated by a process controller within a remotely-located control station.
- a valve positioning mechanism of the type in which a valve actuator located within a process environment moves the valve stem in accordance with a command signal generated by a process controller within a remotely-located control station.
- OMPI generally has a local feedback scheme for terminating the operation of said actuator when the valve attains a final position as dictated by the command signal.
- a remote feedback system generates an output signal for transmission to the remotely-located control station, the frequency of the output signal being indicative of—the status of th& valve-.
- the output signal is communicated to the control station via a two-wire transmission line, commonly used for process control instrumentation communications, which also serves to transmit the command signal from the control station to the valve actuator.
- the feedback system includes an oscillator whose output frequency changes in accordance with the induc ⁇ tance value of a variable inductor responsive to changes in the status of the valve.
- the command signal initi ⁇ ates a pneumatic control signal to the actuator by means of a low-power, electropneumatic switch, which operates at voltage and power levels well within the intrinsically safe limits established for hazardous environments.
- the configuration of the electropneumatic switches achieves a memory function, in that a preexisting valve position will be maintained even in the case of an interruption of the command signal from the controller, for example, as in the case of a power failure.
- the invention functions in a fail-safe mode in case of power failure.
- the memory is disengaged and the valve is automatically set to a fail-safe or other predeter ⁇ mined condition.
- the return to a fail-safe -5- setting can be delayed for a preset period of time after the signal interruption.
- FIG. 1 is a schematic diagram of a first embodiment ⁇ " f a ⁇ valve converter mechanism in accordance with the- present invention
- FIG. 2 is a partial schematic of an embodiment of a valve positioner mechanism in accordance with the present invention.
- FIGS. 3A through 3E are detailed schematics of the circuitry of the INTERFACE CARD portion of FIG. 1;
- FIG. 4 is a detailed schematic of the circuitry of the FIELD ELECTRONICS portion of FIG. 1;
- FIGS. 5A and 5B are detailed views of the variable inductor of the pneumatic transducer of FIG. 1;
- FIG. 6 is a graph depicting the relationship be ⁇ tween oscillator frequency and variable inductor arma ⁇ ture position;
- FIG. 7 is a schematic . diagram of a second embodi ⁇ ment of a valve converter mechanism in accordance with the present invention.
- FIG. 1 there is depicted a process control system 10 employing a novel scheme for adjusting the setting of a valve 11, to vary the rate of passage of process fluids therethrough.
- OMPI tional controller mechanism 13 a device whose con ⁇ struction and operation are well known to those skilled in the process control arts, is the source of command signals which initiate valve " action.
- the controller compares an incoming measurement signal indicating the value of the particular process variable being controlled, with a predetermined set ⁇ point.-signal re_p esenting the desired value of that variable, and generates an appropriate command—signal —. over a line 15.
- This command signal is intended to effect a change in the setting of the valve, so as to drive the measured value of the process toward the desired level.
- the valve as shown in FIG. 1 is pneumatically- actuated, ' although the teachings of the present inve ⁇ - tion are equally applicable to a valve operated by an electrical or other conventional mechanism.
- a pneuma ⁇ tic signal supplied via an air line 17 is applied to any one of a variety of pneumatically-powered drive mechanisms, represented generally by reference numeral 1 , which is coupled to a stem 21 of the valve.
- raising of the valve stem further opens the valve, while lowering the stem closes the valve, although oppositely functioning configura ⁇ tions are possible.
- the circuitry of the field electronics assembly 24, also to be described hereinafter, accepts the electri ⁇ cal signal, usually in the form of a current, from the two-wire transmission line 23, and directs the signal to either of a pair of electropneumatic switches 25, 26. These switches initiate * the flow of pneumatic signals for control purposes.
- the top switch 25 effects a. decrease in the pneumatic pressure ultimately supplied to the valve actuator 19, while the bottom switch 26 increases the pressure.
- Each of the switches 25, 26 includes an outer housing 27 in which there are an upper air chamber 29 and a lower air chamber 33.
- the bottom of the upper chamber is defined by a flexible diaphragm 35.
- a nozzle 36 permits communication of air between the upper chamber and the exterior of the housing through a line 37.
- a flapper 38 normally rests against the nozzle opening, sealing off the nozzle against passage of air and permitting pressurization of the upper chamber.
- An outlet port 39 is in fluid communication with the lower chamber 33.
- a plate 42 Disposed beneath the diaphragm 35 is a plate 42 supported upon and pivotable about a second flexible diaphragm 43.
- a pedestal 44 fastened to the underside
- OMPI -8- of this plate receives an upward bias from a helical spring 45 seated within the lower air chamber 31, so as to maintain the plate in intimate contact with the diaphragm 35.
- Instrument air from a supply 46 typically at 20 psi, is introduced into the upper chamber 29 via a channel 47 and a restrictor 48.
- the flapper ⁇ 3S is sealed against—the—n&zzle 36, the pressure de ⁇ veloped within the upper chamber forces the diaphragm 35 downwardly, causing a gasket 49 located in the underside of the pedestal 44 to seat firmly against a second nozzle 50, despite the upward bias provided by the spring 45. This condition occurs with the electro- pneumatic switch in the "off" position.
- a solenoid assembly 51 is located atop each elec- tropneumatic switch, adjacent the flapper 38. In the absence of an actuating signal to the solenoid, the spring force of the flapper keeps the flapper tightly pressed against the nozzle 36. However, when a current signal is applied to the solenoid, an electromagnet 53 attracts the flapper away from contact with the nozzle. The pressure in the upper chamber 29 decreases, al ⁇ lowing the diaphragm 35 to rise, in turn lessening the force applied against the plate 42. The spring 45 lifts the pedestal and gasket 49 away from the second nozzle 50, allowing the flow of air between the outer port 39 and an inlet line 55, via the lower chamber 33 and the nozzle 50. This represents the "on" condition.
- the outlet port 39 is vented to the atmosphere, so that excess pressure coupled to the inlet line 55 from elsewhere in the pneumatic network can be released.
- this switch acts to decrease the pressure within the pneumatic lines leading ultimately to the valve actuator.
- the outlet port is connected to the 20 psi air supply 46.
- 20 psi air is supplied to the pneumatic control lines, in effect increasing the pressure.
- the interface card 22 and field elec ⁇ tronics assembly 24 acting in concert selectively actuate either switch 25 or switch 26, depending on whether the process conditions call for line pressure- to the valve to be decreased or increased.
- the electro- pneumatic switches which usually are located within the process environments, are electrically triggerable, they have a very low power consumption.
- the considerable motive power which effects the move ⁇ ment of the valve is supplied by the pneumatic pres ⁇ sure, only minimal electrical energy is required to activate the switches, to appropriately route the flow of air.
- the valve control system according to the present invention can operate effectively at current and voltage levels which are within the intrinsically safe limits typically required for safe operation within hazardous or explosive atmospheres. Such levels are defined in the publication, "Intrinsically Safe Apparatus for Use in Division 1 Hazardous Locations," published by The National Fire Protection Association, the contents of which are hereby incorporated by reference.
- the SPEC 200 family of electronic control ⁇ lers manufactured by The Foxboro Company, Foxboro, Massachusetts generates electrical control signals within these intrinsically safe operating limits, and is compatible with the operating requirements of the present invention. Since the electropneumatic switches
- OV.PI utilize a solenoid, which is an inductive, energy- storing device, a shunt protective component of some sort must be coupled to the solenoid to suppress transient voltages or currents above the safe limits.
- a shunt protective component of some sort must be coupled to the solenoid to suppress transient voltages or currents above the safe limits.
- the pneumatic signal is supplied over a line 56 to a pneumatic transmitter 57.
- the transmitter together with a standard pneumatic relay 59 (such as the Model 40 Relay also manufactured by The Foxboro Company) comprise a pneumatic transducer assembly 61.
- a standard pneumatic relay 59 such as the Model 40 Relay also manufactured by The Foxboro Company
- an expandable receiver bellows 63 is attached at its lower end to a molinting base 65, and at its upoer end to one end of a lever arm 67.
- the lever arm is able to pivot about a fulcrum 69 on a balance bar 71, to cause repositioning of a flapper 73 relative to a nozzle 75.
- the nozzle is connected via a pneumatic line 77 to the standard relay 59 and to the air supply 46.
- the spacing of the flapper relative to the nozzle deter- mines the magnitude of an amplified output signal pro ⁇ pokerd by the relay on the output line 17, and in turn supplied to the valve actuator 19.
- the flapper When air entering from the line 56 causes the bellows to expand, the flapper is pivoted closer to the nozzle, resulting in an increase in the output pressure of the relay.
- the flapper contracts, the flapper is withdrawn from the nozzle, decreasing the relay output.
- a feedback bellows 81 is inter ⁇ posed between the base 65 and the balance bar 71.
- a spring 83 provides a downward bias on the left-hand end of the bar.
- this balance bar similarly can be pivoted about a flexure 84 to relocate the nozzle relative to the flapper.
- the pneumatic signal into the feedback bellows 81 comes from the same output signal of the relay 59 as is supplied to the valve actuator 19.
- changes in the actuation pressure to the valve are reflected by an increase or decrease in the internal pressure of the feedback bellows 81, which causes the bellows to expand or contract accordingly.
- the movement of the bellows repositions the nozzle 75 relative to the flapper 73 until a new equilibrium position is reestab ⁇ lished, at which point no further changes in the relay output occur.
- the action of the receiver bellows prompts a pneumatic drive signal to the valve actuator until it is counterbalanced by the corresponding action of the feedback bellows.
- valve positioning mechanism Due to the fact that the feedback between the valve actuator 19 and the pneumatic transmitter 57 is accom- pushed by means of a pressure signal to the feedback bellows 81, the type of valve positioning mechanism depicted in FIG. 1 is known as a valve converter. However, as shown in FIG. 2, the feedback also can be provided by a direct mechanical linkage 85 between the valve stem 21 and the balance bar 71. In this arrange ⁇ ment, the valve positioning mechanism is more accurate ⁇ ly known- as a valve p ⁇ sitioner. _.
- an armature 87 in the shape of a truncated triangular wedge, which forms part of a variable inductor assembly 89.
- the inductor is a component within an oscillator circuit encompassed within the circuitry of the field electronics assembly 24 (see FIG. 4).
- the oscillator can be any conven ⁇ tional circuit whose output frequency is dependent on the value of the variable inductor, and as such its details will not be further discussed herein.
- the upward and downward movement of the balance bar in response to feedback signals supplied to the pneumatic transmitter, repositions the armature within the air gap 91 of a magnetic assembly 93 included within the variable in ductor, as seen more clearly in FIGS.
- FIG. 6 demonstrates the linear relationship between oscillator frequency and armature position over the normal operating range of the oscillator.
- the oscillator output frequency itself is uniquely related to the true valve position, in the case of a valve positioner, or to the valve position actuator pressure, in the case of a valve converter.
- This frequency signal is fed back along the same two-way transmission line 23 to the interface card 22, to be processed in a manner described below.
- the devi ⁇ ation amplifier amplifies the difference between the controller command signal and the feedback voltage signal, and inputs the resulting error voltage into both a deadband comparator stage 107 and a deviation band comparat ⁇ -r stage 109.
- one or the other of these stages supplies a current trigger signal to the appropriate electropneumatic switch 25, 26 so as to properly repo ⁇ sition the valve 13.
- a current source 111 generates only a quiescent current level for powering the - ariable frequency oscillator in the field elec ⁇ tronics assembly 24. If the amplified error voltage signal is greater than the deadband threshold voltage VR1 but less than a deviation band threshold voltage VR2 (also supplied from an external source), the dead ⁇ band comparator 107 is activated.
- the switched current source 111 causes the switched current source 111 to operate in a pulsed mode, the pulse width and duty cycle of the pulse train having been previously determined to yield efficient repositioning of the valve.
- the pulsed mode in effect offers a fine-tuning type adjustment.
- the polarity of the error voltage determines the sense of the output current delivered to the field electronics assembly 24.
- the field electronics assembly 24 receives from the interface card 22 either the +1 or -I current signal, and actuates either "increase” switch 26 or “decrease” switch 25 respec ⁇ tively. If the magnitude of the error voltage is consider ⁇ ably greater, and in fact exceeds the deviation band threshold, the deviation band comparator stage 109 takes over. This comparator drives the • switched current source 111 in a "full-on” mode. Again, the polarity of the error voltage determines the current sense, and therefore which electropneumatic switch is actuated.
- the current sources will supply- only a quiescent current level to the oscillator, and both electropneumatic switches will be in the "off” position.
- an initialization circuit (not shown) senses the feedback voltage from the frequency-to-voltage converter 101 (see FIG. 3B) which indicates valve position, and resets the con- troller so as to achieve a "bumpless" transfer.
- FIG. 7 an alternate embodiment of a valve converter in accordance with the present invention is achieved by substituting a slightly modi- fied electropneumatic switch 113 for the top switch 25 (see FIG. 1).
- This modified switch functions in basically the same manner as the electropneumatic switches 25 and 26 discussed , in detail above.
- the only difference “ is that "" the nozzle 36' is located on the opposite side of the flapper 38, so that in the "off" condition, i.e., with the solenoid 51 deactivated, the flapper is not in contact with the nozzle.
- switch 113 is "normally open,” to achieve the memory function described above with • reference to the embodiment of FIG. 1.
- appropriate modifications must be made to the electronic circuitry of the field elec ⁇ tronics assembly 24 and/or the interface card 22. whereas in the previous embodiment the absence of electrical power to both of the switches 25, 26 would maintain the status quo, now power must be maintained to the modified switch 113 to reach the same result.
- the switch 113 As long as electrical power above a predetermined threshold value is maintained to the electropneumatic switch 113 along a line 125 from the field electronics assembly 24, the switch remains off. However, once the electrical power drops below the predetermined level, the switch 113 turns on and permits venting of any excess pressure within the receiver bellows 63 of the pneumatic transducer 61. This in turn causes the valve to go to a fail-safe position, as determined by the characteristics of the process being controlled. It is also possible to incorporate within the pneumatic system a conventionally known pneumatic delay device, to forestall the movement of the valve to the failsafe position until after passage of a predetermined amount of time.
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Automation & Control Theory (AREA)
- Servomotors (AREA)
- Control Of Position Or Direction (AREA)
- Arrangements For Transmission Of Measured Signals (AREA)
- Control Of Fluid Pressure (AREA)
- Color Television Systems (AREA)
Abstract
Un mécanisme de positionnement de soupape, pouvant avoir la configuration soit d'un positionneur soit d'un convertisseur, agit en réponse à un signal de commande envoyé par une ligne de transmission à deux fils par un contrôleur situé à distance, et fournit un signal de réaction au contrôleur par la même ligne de transmission à deux fils. En fonction de la configuration utilisée, ce signal de réaction vérifie soit que la soupape a pris la position indiquée par le contrôleur soit que la pression d'actionnement de la soupape est celle indiquée par le contrôleur. Le signal de commande déclenche un commutateur électropneumatique qui initie l'écoulement d'air pour actionner un mécanisme pneumatique entraînant la tige de soupape. Un inducteur variable dont la valeur d'inductance dépend de la pression d'actionnement/position de la soupape, fait partie d'un oscillateur dont la fréquence de sortie varie avec la valeur d'inductance. L'oscillateur fournit à son tour un signal de mesure au contrôleur par l'intermédiaire de la ligne de transmission à deux fils, la fréquence du signal étant proportionnelle à la pression d'actionnement/position de la soupape. Le contrôleur termine l'ajustement de la soupape lorsque le signal de mesure est identique à la valeur de consigne du contrôleur. Lors d'une perte de puissance, la soupape peut être maintenue dans une position préexistante ou, dans une autre variante, elle peut reprendre un état de sécurité, avec ou sans temporisation prédéterminée.A valve positioning mechanism, which may be configured as either a positioner or a converter, acts in response to a control signal sent over a two-wire transmission line from a remote controller, and provides a signal. feedback to the controller through the same two-wire transmission line. Depending on the configuration used, this feedback signal verifies either that the valve has assumed the position indicated by the controller or that the actuating pressure of the valve is that indicated by the controller. The control signal triggers an electro-pneumatic switch which initiates the flow of air to actuate a pneumatic mechanism driving the valve stem. A variable inductor whose inductance value depends on the actuating pressure / valve position, is part of an oscillator whose output frequency varies with the inductance value. The oscillator in turn provides a measurement signal to the controller via the two-wire transmission line, the frequency of the signal being proportional to the actuating pressure / valve position. The controller completes the valve adjustment when the measurement signal is the same as the controller setpoint. In the event of a loss of power, the valve can be maintained in a pre-existing position or, in another variant, it can resume a safe state, with or without a predetermined time delay.
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US42480482A | 1982-09-27 | 1982-09-27 | |
US424804 | 1982-09-27 |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0120035A1 true EP0120035A1 (en) | 1984-10-03 |
Family
ID=23683933
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP83902847A Withdrawn EP0120035A1 (en) | 1982-09-27 | 1983-08-08 | Valve converter/positioner with remote feedback and memory |
Country Status (8)
Country | Link |
---|---|
EP (1) | EP0120035A1 (en) |
JP (1) | JPS59501805A (en) |
KR (1) | KR840006261A (en) |
AU (1) | AU1945883A (en) |
CA (1) | CA1200590A (en) |
IT (1) | IT1197718B (en) |
NO (1) | NO842080L (en) |
WO (1) | WO1984001445A1 (en) |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1991005293A1 (en) * | 1989-10-02 | 1991-04-18 | Rosemount Inc. | Field-mounted control unit |
DK142593D0 (en) * | 1993-12-21 | 1993-12-21 | Ole Cramer Nielsen | DEVICE FOR MANAGING A VALVE |
US5924516A (en) * | 1996-01-16 | 1999-07-20 | Clark Equipment Company | Electronic controls on a skid steer loader |
DE102009010339A1 (en) * | 2009-02-25 | 2010-08-26 | Hoerbiger Automatisierungstechnik Holding Gmbh | Proportional control valve for pneumatic applications |
CN102797893A (en) * | 2012-08-16 | 2012-11-28 | 天津开利达控制技术开发有限公司 | Electric actuator with photoelectric positioning mechanism |
JP6295222B2 (en) * | 2015-03-17 | 2018-03-14 | アズビル株式会社 | Positioner |
DE102015213206A1 (en) * | 2015-07-15 | 2017-01-19 | Robert Bosch Gmbh | Method and circuit arrangement for determining a position of a movable armature of an electromagnetic actuator |
US10711907B2 (en) | 2017-11-07 | 2020-07-14 | Black Diamond Engineering, Inc. | Line replaceable control valve positioner/controller system |
CN111637276B (en) * | 2019-03-01 | 2022-10-21 | 自贡新地佩尔阀门有限公司 | Feedback device of control valve positioner |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR1186999A (en) * | 1957-06-07 | 1959-09-04 | Ibm France | Remote control and monitoring device |
FR2044054A5 (en) * | 1969-05-07 | 1971-02-19 | Amri | |
US3878376A (en) * | 1973-12-17 | 1975-04-15 | Martin Marietta Corp | Computer operated solenoid valve pressure control system |
FR2300365A1 (en) * | 1975-02-10 | 1976-09-03 | Commissariat Energie Atomique | Remote controlled positioning system - uses transmitter and receivers employing frequency comparison techniques for accurate positioning |
US4348673A (en) * | 1978-10-13 | 1982-09-07 | The Foxboro Company | Instrumentation system with electric signal transmitter |
-
1983
- 1983-08-08 EP EP83902847A patent/EP0120035A1/en not_active Withdrawn
- 1983-08-08 AU AU19458/83A patent/AU1945883A/en not_active Abandoned
- 1983-08-08 JP JP58502938A patent/JPS59501805A/en active Pending
- 1983-08-08 WO PCT/US1983/001225 patent/WO1984001445A1/en not_active Application Discontinuation
- 1983-09-26 KR KR1019830004499A patent/KR840006261A/en not_active Application Discontinuation
- 1983-09-26 CA CA000437562A patent/CA1200590A/en not_active Expired
- 1983-09-26 IT IT49032/83A patent/IT1197718B/en active
-
1984
- 1984-05-24 NO NO842080A patent/NO842080L/en unknown
Non-Patent Citations (1)
Title |
---|
See references of WO8401445A1 * |
Also Published As
Publication number | Publication date |
---|---|
WO1984001445A1 (en) | 1984-04-12 |
NO842080L (en) | 1984-05-24 |
IT1197718B (en) | 1988-12-06 |
CA1200590A (en) | 1986-02-11 |
JPS59501805A (en) | 1984-10-25 |
IT8349032A0 (en) | 1983-09-26 |
AU1945883A (en) | 1984-04-24 |
KR840006261A (en) | 1984-11-22 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JPS6184715A (en) | Automatic setting reducing valve | |
EP0503894B1 (en) | I/P converters | |
EP0120035A1 (en) | Valve converter/positioner with remote feedback and memory | |
US5899064A (en) | Servo-actuator with fail safe means | |
US6267349B1 (en) | Precision valve control | |
CA1335116C (en) | Two-wire i/p converter with energy storage | |
EP1318341A2 (en) | Flow rate control apparatus | |
EP0040241A1 (en) | Current to pressure converter apparatus | |
US5787925A (en) | Pneumatically servoed gas pressure regulator | |
EP1539528B1 (en) | Electro-fluidic control device and method for controlling an electric current collector | |
US4731996A (en) | Position transmitter for a pneumatic-pneumatic or electro-pneumatic converter | |
US6349627B1 (en) | Electropneumatic positioner | |
US5469877A (en) | Electric to pneumatic transducer | |
EP0177150B1 (en) | Electropneumatic converters | |
US5007447A (en) | Pneumatic feed safety apparatus with re-setting control | |
CA2078055A1 (en) | A safety and automatic stop device, in particular for gas expansion stations | |
US4648245A (en) | Electro-hydraulic actuator or positioning drive for continuous control or regulation operations | |
US4926905A (en) | Manually operated air valve and actuator in combination control a hydraulic spool valve for maneuvering heavy equipment | |
US4784039A (en) | Electric and pneumatic valve positioner | |
JPH084708A (en) | Operator | |
JP2592594B2 (en) | Automatic setting pressure reducing valve | |
KR100285801B1 (en) | Method for controlling electro/pneumatic device for controlling opening/closing position of valve automatically and thereby electro/pneumatic device | |
JPH04185902A (en) | Positioner | |
JPH053751Y2 (en) | ||
JPH0431336B2 (en) |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
17P | Request for examination filed |
Effective date: 19840515 |
|
AK | Designated contracting states |
Designated state(s): DE FR GB NL SE |
|
RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: THE FOXBORO COMPANY |
|
17Q | First examination report despatched |
Effective date: 19860627 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
18D | Application deemed to be withdrawn |
Effective date: 19861108 |
|
RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: OLSEN, EVERETT, O. Inventor name: GRAVES, NORMAN, S. Inventor name: PETERSON, NEAL, D. Inventor name: BOLZ, CARL, W. |