Positioner

Abstract

A positioner is provided with a control calculating portion 1 including first and second calculating portions. The first calculating portion, a valve opening detecting portion, and a first pressure sensor are contained in a first case. The second calculating portion, an electropneumatic converting portion, a pneumatic circuit portion, and a second pressure sensor are contained in a second case. The first case is assembled together with the valve, and the second case is located in a position away from the valve. Output signals from the first calculating portion, which are a control signal MV (a PWM signal) and a detected pressure signal S1 (wherein a detected pressure signal S1 has been converted into a digital signal, are sent to the second calculating portion through cables 16.

Claims

1. A positioner comprising: a control calculating portion that inputs an opening setting signal for a valve, sent from a higher-level device, and an actual opening signal expressing the current opening of the valve, and generates a control signal from the opening setting signal and the actual opening signal; an electropneumatic converting portion that converts the control signal from the control calculating portion into an air pressure; a pneumatic circuit portion that uses, as an input air pressure, an air pressure that has been converted by the electropneumatic converting portion, for amplifying this input air pressure to form an output air pressure, and outputs this output air pressure to the valve; a valve opening detecting portion that detects the current opening of the valve to produce the actual opening signal for the control calculating portion; a first calculating portion and a second calculating portion, which structure the control calculating portion; a first pressure sensor that detects an output air pressure from the pneumatic circuit portion at the valve; a second pressure sensor that detects an output air pressure from the pneumatic circuit portion to the valve or an input air pressure from the electropneumatic converting portion to the pneumatic circuit portion; a first case that contains the first calculating portion, the valve opening detecting portion, and the first pressure sensor; and a second case that contains the second calculating portion, the electropneumatic converting portion, the pneumatic circuit portion, and the second pressure sensor, wherein: the first case is assembled together with the valve; the second case is located in a position away from the valve; the first calculating portion inputs an opening setting signal that is sent from the higher-level device, the actual opening signal that is sent from the valve opening detecting portion, and a detected pressure signal from the first pressure sensor; and the second calculating portion inputs an output signal from the first calculating portion, and a detected pressure signal from the second pressure sensor.

2. The positioner as set forth in claim 1, wherein: the first calculating portion generates, and sends to the second calculating portion, the control signal, based on the opening setting signal that is sent from the higher-level device and the actual opening signal that is sent from the valve opening detecting portion; and the second calculating portion performs diagnostics on the valve based on the detected pressure signal from the first pressure sensor, sent through the first calculating portion, and the detected pressure signal from the second pressure sensor.

3. The positioner as set forth in claim 1, wherein: the first calculating portion generates, and sends to the second calculating portion, the control signal, based on the opening setting signal that is sent from the higher-level device and the actual opening signal that is sent from the valve opening detecting portion, and also performs diagnostics on the valve based on the detected pressure signal from the second pressure sensor, sent through the second calculating portion, and the detected pressure signal from the first pressure sensor.

4. The positioner as set forth in claim 1, wherein: the first calculating portion generates, and sends to the second calculating portion, the based on the opening setting signal, sent from the higher-level device, the actual opening signal, sent from the valve opening detecting portion, the detected pressure signal from the first pressure sensor, and the detected pressure signal from the second pressure sensor.

Description

BRIEF DESCRIPTIONS OF THE DRAWINGS

(1) FIG. 1 is a structural diagram illustrating the critical portions in an example of a positioner according to the present disclosure.

(2) FIG. 2 is a diagram showing comparisons of various aspects of a conventional positioner that is provided with a pressure sensor (a single-unit positioner and a conventional separated-type positioner) and a positioner according to the present invention.

(3) FIG. 3 is a diagram showing an example wherein the input air pressure Pn, inputted into the pneumatic circuit portion from the electropneumatic converting portion, is the air pressure detected by the second pressure sensor.

(4) FIG. 4 is a diagram illustrating the structure in a conventional single-unit positioner.

(5) FIG. 5 is a diagram illustrating an example structure for a conventional single-unit positioner that is equipped with a pressure sensor.

(6) FIG. 6 is a diagram illustrating an example structure for a conventional separate-type positioner that is equipped with a pressure sensor.

DETAILED DESCRIPTION

(7) Examples according to the present disclosure will be explained below in detail, based on the drawings. FIG. 1 is a structural diagram illustrating the critical portions in an example of a positioner according to the present disclosure. In this figure, the structural elements that are identical or equivalent to the structural elements explained in reference to FIG. 6 are indicated by codes that are identical to those of FIG. 6, and explanations thereof are omitted.

(8) In a positioner 200 (200D) according to the present example, the control calculating portion 1 is structured from a first calculating portion 1-1 and a second calculating portion 1-2, where the first calculating portion 1-1, a valve opening detector (valve opening detecting portion) 4, and a first pressure sensor 5 are contained within a first case 10-1, and the second calculating portion 1-2, an electropneumatic converting portion 2, a pneumatic circuit portion 3, and a second pressure sensor 6 are contained within a second case 10-2.

(9) Moreover, the first case 10-1, which contains the first calculating portion 1-1, the valve opening detector 4, and the first pressure sensor 5, is assembled together with the valve 300, and the second case 10-2, which contains the second calculating portion 1-2, the electropneumatic converting portion 2, the pneumatic circuit portion 3, and the second pressure sensor 6, is placed in a position away from the valve 300.

(10) While this positioner 200D is also a separated-type positioner positioner, as is the positioner 200C illustrated in FIG. 6, the first calculating portion 1-1, the valve opening detector 4, and the first pressure sensor 5, which are the calculating system, is contained in the first case 10-1, where the second calculating portion 1-2, the electropneumatic converting portion 2, the pneumatic circuit portion 3, and the second pressure sensor 6, which are the pneumatic system, are contained in the second case 10-2, so the calculating system and the pneumatic system are separated.

(11) That is, in the positioner 200D, the calculating system and the pneumatic system are cut off from each other, where the calculating system is assembled together with the valve 300, and the pneumatic system is located in a position away from the valve 300. Note that in the first case 10-1 and the second case 10-2, the various components are supplied power from respective separate power supplies.

(12) Moreover, in this positioner 200D, the opening setting signal Xsp, sent from the higher-level device 100, the actual opening signal Xpv, sent from the valve opening detector 4, and the detected pressure signal S1, sent from the first pressure sensor 5, are inputted into the first calculating portion 1-1, and the output signal from the first calculating portion 1-1 (that is, a control signal MV and a detected pressure signal S1 (wherein the detected pressure signal S1 has been converted into a digital signal)), and the detected pressure signal S2 from the second pressure sensor 6, are inputted into the second calculating portion 1-2.

(13) In this case, the output signals from the first calculating portion 1-1 (the control signal MV and the detected pressure signal S1) are sent from the first case 10-1 side to the second case 10-2 side, instead of the actual opening signal Xpv from the valve opening detector 4 and the detected pressure signal S1 from the first pressure sensor 5. That is, the output signals from the first calculating portion 1-1 (that is, the control signal MV and the detected pressure signal S1) are sent through the cable 16 from the first calculating portion 1-1 to the second calculating portion 1-2.

(14) These output signals (the control signal MV and the detected pressure signal S1) that are sent through the cable 16 are digital signals, that is, the control signal MV is a PWM signal (a pulse width modulation signal), and the detected pressure signal S1 is the detected pressure signal S1 that has been converted into a digital signal, and thus they are robust to noise.

(15) Note that while in this example the output signals from the first calculating portion 1-1 (the control signal MV and the detected pressure signal S1) are sent through the cable 16 to the second calculating portion 1-2, that is, while the output signals from the first calculating portion 1-1 (the control signal MV and the detected pressure signal S1) are sent to the second calculating portion 1-2 through a physical cable, they may be sent via radio instead. Moreover, the output signals (the control signal MV and the detected pressure signal S1) from the first calculating portion 1-1 need not necessarily be digital signals, but may instead be strong analog signals.

(16) When the output signals from the first calculating portion 1-1 (the control signal MV and the detected pressure signal S1) are sent, then, in the second calculating portion 1-2, the control signal MV is sent to the electropneumatic converting portion 2, while, on the other hand, diagnostics are performed on the valve 300 based on the detected pressure signal S1, that is, the detected pressure signal S1 from the first pressure sensor 5 that has been converted into a digital signal, and on the detected pressure signal S2 from the second pressure sensor 6. In this example, air leak detection is performed based on the difference between the air pressure detected by the first pressure sensor 5 and the air pressure detected by the second pressure sensor 6. The diagnostic result by the second calculating portion 1-2 is sent through the cable 16 to the first calculating portion 1-1, to be sent from the first calculating portion 1-1 to the higher-level device 100. Note that the diagnostic results by the second calculating portion 1-2 may be, for example, displayed on the positioner 200D.

(17) This positioner 200D also produces other effects, such as the following. This positioner 200D is referred to below as a calculating/pneumatic system-separated positioner.

(18) (1) Because the valve opening detector 4 and the calculating portion 1-1 are assembled together into a single unit, there is no need for a long signal line for the actual opening signal Xpv that would be susceptible to the effects of noise.

(19) (2) Because the pressure sensor 5 and the calculating portion 1-1 are assembled together into a single unit, there is no need for a long signal line for the detected air pressure signal S1 that would be susceptible to the effects of noise.

(20) (3) There is no need for noise testing on lines that would transmit minute changes, enabling noise prevention performance with countermeasures similar to those that are conventional.

(21) (4) The development lead time is shortened and the development cost is reduced through reducing the number of issues requiring noise testing.

(22) (5) Miniaturization is facilitated through having only the valve opening detector 4, the pressure sensor 5, and the calculating portion 1-1, with robustness to vibration similar to that of the conventional separated type.

(23) (6) Because the valve opening detector 4, the pressure sensor 5, and the calculating portion 1-1 are located together, temperature correction for the valve opening detector 4 and the pressure sensor 5 can be performed accurately.

(24) (7) An anti-explosive structure is possible through resin molding of the valve opening detector 4, the pressure sensor 5, and the calculating portion 1-1 alone.

(25) (8) The calculating portion 1-2, the electropneumatic converting portion 2, the pneumatic circuit portion 3, and the pressure sensor 6 can be located in a safety zone, eliminating the need for an anti-explosive structure for these parts, enabling a reduction in costs.

(26) In FIG. 2, with the conventional single-unit positioner 200B (FIG. 5) listed as Single-Unit Type, and the conventional separated-type positioner 200C (FIG. 5) listed as Conventional Separated Type, various attributes are compared for the case of the Calculating/Pneumatic Separated Type of the positioner 200D of the present example (FIG. 1).

(27) Note that while in the example set forth above the output air pressure Po from the pneumatic circuit portion 3 to the valve 300 was detected by the second pressure sensor 6, the input air pressure Pn, into the pneumatic circuit portion 3 from the electropneumatic converting portion 2, may be detected instead, with the detected air pressure sent to the second calculating portion 1-2 as the detected air pressure signal S2, as illustrated in FIG. 3.

(28) Moreover, while, in the example set forth above, diagnostics were performed in the second calculating portion 1-2 on the valve 300 based on the detected pressure signal S1' from the first calculating portion 1-1 (the detected pressure signal S1 that has been converted into a digital signal) and on the detected pressure signal S2 from the second pressure sensor 6, the diagnostics on the valve 300 may instead be performed in the first calculating portion 1-1 based on a detected pressure signal S2 from the second calculating portion 1-2 (where the detected pressure signal S2 has been converted into a digital signal) and on the detected pressure signal S1 from the first pressure sensor 5.

(29) Moreover, in the first calculating portion 1-1, high-speed control may be performed through the use of PID control calculations when calculating the control signal MV from the detected pressure signal S1, from the first pressure sensor 5, and the detected pressure signal S2, from the second calculating portion 1-2. Moreover, the control signal MV may be calculated through executing PID control calculations on the difference between the opening setting signal Xsp and the actual opening signal Xpv in the second calculating portion 1-2 instead, and the division of responsibilities, into the first calculating portion 1-1 and the second calculating portion 1-2, for the control calculating portion 1, may be performed with flexibility.

FURTHER EXAMPLES

(30) While the present disclosure has been explained above in reference to examples, the present disclosure is not limited to the examples set forth above. The structures and details in the present disclosure may be varied in a variety of ways, as can be understood by one skilled in the art, within the scope of technology in the present disclosure.