Double nozzle type smart positioner

Abstract

Provided is a double nozzle type positioner, which includes a flapper (1), a first nozzle (2) and a second nozzle (3) disposed at both sides based on the flapper (1), a first orifice (4) configured to maintain a constant pressure of the first nozzle (2), a second orifice (5) configured to maintain a constant pressure of the second nozzle (3), a first pilot valve (6) having an input portion connected to a feed pressure, a second pilot valve (7) having an input portion connected to an output portion of the first pilot valve (6), a discharge hole (8) connected to an output portion of the second pilot valve (7), and an actuator (9) connected to the output portion of the first pilot valve (6) and the input portion of the second pilot valve (7). If the first nozzle (2) is opened due to the movement of the flapper (1), the second nozzle (3) is closed, and if the first nozzle (2) is closed, the second nozzle (3) is opened.

Claims

1. A double nozzle type positioner, comprising: a flapper (1); a first nozzle (2) and a second nozzle (3) disposed at both sides of the flapper (1); wherein when the first nozzle (2) is opened due to the movement of the flapper (1), the second nozzle (3) is closed, and when the first nozzle (2) is closed, the second nozzle (3) is opened; a first pilot valve (6) connected to the first nozzle (2); a second pilot valve (7) connected to the second nozzle (3); a constant pressure source configured to constantly supply a pneumatic pressure to the first nozzle (2), the first pilot valve (6), the second nozzle (3) and the second pilot valve (7); a first orifice (4) configured to maintain the pneumatic pressure supplied from the constant pressure source to the first nozzle (2) and the first pilot valve (6) constantly; and a second orifice (5) configured to maintain the pneumatic pressure supplied from the constant pressure source to the second nozzle (3) and the second pilot valve (7) constantly, wherein an input portion of the first pilot valve (6) is connected to a feed pressure, and the first pilot valve (6) is configured to transfer the feed pressure supplied from the input portion of the first pilot valve (6) to an output portion of the first pilot valve (6), according to the pneumatic pressure supplied from the constant pressure source to the first pilot valve (6) which is exclusively controlled by the opening and closing of the first nozzle (2), wherein the output portion of the first pilot valve (6) is connected to an input portion of the second pilot valve (7), wherein the second pilot valve (7) is configured to transfer the feed pressure supplied to the input portion of the second pilot valve (7) to an output portion of the second pilot valve (7), according to the pneumatic pressure supplied from the constant pressure source to the second pilot valve (7) which is exclusively controlled by the opening and closing of the second nozzle (3), and the output portion of the second pilot valve (7) is connected to a discharge hole (8), wherein a fluid junction between the output portion of the first pilot valve (6) and the input portion of the second pilot valve (7) is connected to an actuator (9).

2. The double nozzle type positioner according to claim 1, wherein the movement of the flapper (1) is controlled by a single control current.

3. The double nozzle type positioner according to claim 2, wherein the flapper (1) is configured to move in opposite directions according to polarities of the single control current.

Description

THE DRAWINGS

(1) FIG. 1 is a diagram showing an existing positioner including a single nozzle, a single flapper and a single pilot valve.

(2) FIG. 2 shows an existing arrangement where two positioners are coupled to a single actuator in order to overcome the drawback of the positioner of FIG. 1.

(3) FIG. 3 is a diagram showing a double nozzle type positioner according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

(4) Hereinafter, a double nozzle type positioner according to an embodiment of the present disclosure will be described in detail with reference to FIG. 3.

(5) FIG. 3 is a schematic diagram showing a double nozzle type positioner according to an embodiment of the present disclosure. The double nozzle type positioner includes a flapper 1, a first nozzle 2, a second nozzle 3, a first orifice 4, a second orifice 5, a first pilot valve 6, a second pilot valve 7 and a discharge hole 8. The first nozzle 2 and the second nozzle 3 are disposed at both sides of the flapper 1 based on the flapper 1. If the first nozzle 2 is closed due to the movement of the flapper 1, the second nozzle 3 is opened, and if the first nozzle 2 is opened, the second nozzle 3 is closed. If the flapper 1 is located at the center, both first and second nozzles 2, 3 are opened. The movement of the flapper 1 may be controlled by means of a control current provided to the flapper. For example, the flapper 1 may be configured to move in opposite directions according to polarities of a single control current.

(6) The first nozzle 2 is connected to the first pilot valve 6. A constant pressure source for supplying a constant pressure to the first nozzle 2 and the first pilot valve 6 is connected between them. The second nozzle 3 is connected to the second pilot valve 7. A pressure source for supplying a constant pressure to the second nozzle 3 and the second pilot valve 7 is connected between them. These pressure sources may be a single pressure source. In order to constantly maintain the pressure supplied from the pressure source to the first nozzle 2 and the first pilot valve 6 and to the second nozzle 3 and the second pilot valve 7, the first orifice 4 and the second orifice 5 are respectively provided.

(7) A separate feed pressure is connected to an input portion of the first pilot valve 6, and an output portion of the first pilot valve 6 is connected to an input portion of the second pilot valve 7. An output portion of the second pilot valve 7 is connected to the discharge hole 8. The output portion of the first pilot valve 6 and the input portion of the second pilot valve 7 are coupled and connected to an actuator 9 at a fluid junction.

(8) Regarding the operations, if a positive control current is supplied to the flapper 1, the flapper 1 moves toward the first nozzle 2 to close the first nozzle 2, and the second nozzle 3 is opened. Since the first nozzle 2 is closed, the pressure supplied from the constant pressure source is entirely supplied to the first pilot valve 6. In addition, since the second nozzle 3 is opened, the pressure supplied to the constant pressure source is discharged through the second nozzle 3 and not supplied to the second pilot valve 7. Accordingly, the first pilot valve 6 discharges the input feed pressure through the output portion, and the input portion and the output portion of the second pilot valve 7 are closed. The pneumatic pressure output from the first pilot valve 6 is transferred to the actuator 9 to move the actuator 9, for example, upwards.

(9) If a negative control current is supplied to the flapper 1, the flapper 1 moves toward the second nozzle 3 to close the second nozzle 3, and the first nozzle 2 is opened. As described above, the pressure supplied from the constant pressure source is provided to the second pilot valve 7 and is not provided to the first pilot valve 6. Therefore, the feed pressure input to the first pilot valve 6 is not output, and the input portion and the output portion of the second pilot valve 7 are opened. The pneumatic pressure existing at the actuator 9 is discharged through the second pilot valve 7 to the discharge hole 8, thereby moving the actuator 9, for example, downwards.

(10) If a current is not supplied to the flapper 1, both nozzles are opened, the input portions and the output portions of both the first pilot valve 6 and the second pilot valve 7 are blocked, and the actuator 9 does not move.

(11) The above description is just an example. For example, as an alternative, when a negative current is supplied to the flapper 1, the flapper 1 may move toward the first nozzle 2, and when a positive current is supplied to the flapper 1, the flapper 1 may move toward the second nozzle 3. In addition, the upward or downward movement of the actuator may be performed reversely or in different directions.

(12) In the double nozzle type positioner according to the present disclosure, two positioners may be proportionally controlled by means of two nozzles. Since a polarity of a control current is used, it is possible to control with a low current. Also, since a single current is used, convenient installation and control is ensured. Since two nozzles play a role of a stopper, variations caused by external influences are small.