Pressure-type flow controller

Abstract

A pressure-type flow controller includes a main body provided with a fluid channel between a fluid inlet and a fluid outlet and an exhaust channel between the fluid channel and an exhaust outlet; a pressure control valve fixed to the fluid inlet of the main body for opening/closing the upstream side of the fluid channel; a pressure sensor for detecting the internal pressure of the fluid channel on the downstream side of the pressure control valve; an orifice provided in the fluid channel on the downstream side of the point of branching of the exhaust channel; and an exhaust control valve for opening/closing the exhaust channel.

Claims

1. A pressure-type flow controller, comprising: a main body provided with a gas channel communicating between a gas inlet and a gas outlet and an exhaust channel branched from the gas channel and communicating between the gas channel and an exhaust outlet; a control valve for pressure control provided to the gas channel on an upstream side of a point of branching of the exhaust channel; an orifice provided in the gas channel on a downstream side of the point of branching of the exhaust channel, the orifice having a fixed diameter smaller than a diameter of the gas channel at an upstream side of the orifice and at a downstream side of the orifice and being configured such that a flow rate of a gas passing through the orifice is proportional to a pressure on an upstream side of the orifice when a critical expansion condition is satisfied; a pressure sensor for detecting an internal pressure of the gas channel between the control valve for pressure control and the orifice; a control valve for exhaust control for opening/closing the exhaust channel; and a controller configured to control the control valve for pressure control and the control valve for exhaust control to control the flow rate of the gas flowing downstream of the orifice based on a set flow rate, wherein the controller controls the control valve for pressure control and the control valve for the exhaust control such that the gas between the control valve for pressure control and the orifice is exhausted when the set flow rate is reduced when an opening degree of the control valve for pressure control changes to a smaller opening degree.

2. The pressure-type flow controller according to claim 1, wherein the orifice is provided without a movable body capable of selectively closing a fluid passage of the orifice.

3. The pressure-type flow controller according to claim 1, further comprising a pressure sensor for detecting an internal pressure of the gas channel on the downstream side of the orifice.

4. The pressure-type flow controller according to claim 1, further comprising an another orifice connected in parallel with the orifice and an orifice switching valve for controlling a flow of a gas to the another orifice.

5. The pressure-type flow controller according to claim 4, further comprising a pressure sensor for detecting an internal pressure of the gas channel on the downstream side of the orifice.

6. The pressure-type flow controller according to claim 1, wherein the control valve for pressure control and the control valve for exhaust control are each a piezoelectric-driven metal-diaphragm control valve.

7. The pressure-type flow controller according to claim 6, configured such that a step-down response time to step down a flow rate of a gas flowing through the gas channel is controlled by adjusting an input voltage to a piezoelectric-driven element of the control valve for exhaust control.

8. The pressure-type flow controller according to claim 1, wherein the control valve for exhaust control is a pneumatically actuated valve or an electromagnetically actuated valve.

9. The pressure-type flow controller according to claim 1, configured such that gas in the exhaust channel is forcibly exhausted by a vacuum pump connected to the exhaust outlet.

10. The pressure-type flow controller according to claim 1, wherein gas between the control valve for pressure control and the orifice is exhausted by opening the control valve for exhaust control while temporary closing the control valve for pressure control.

11. The pressure-type flow controller according to claim 1, wherein the orifice is maintained in an open state with pressure on the upstream side of the orifice being controlled to be different from pressure on the downstream side of the orifice.

12. The pressure-type flow controller according to claim 1, wherein no valve is provided between the control valve for pressure control and the orifice along the gas channel.

13. The pressure-type flow controller according to claim 1, wherein the control valve for pressure control and the control valve for exhaust control are proportional control valves.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 A longitudinal cross-sectional view showing the basic configuration of the pressure-type flow controller according to the present invention.

(2) FIG. 2 A system diagram showing the configuration of a gas supply box to which the pressure-type flow controller according to the present invention is applied.

(3) FIG. 3 A line graph showing the step-down response characteristics of the pressure-type flow controller according to the embodiment at the time of continuous steps.

(4) FIG. 4 A line graph showing changes in the input voltages to the piezoelectric-driven elements of the control valve for pressure control 6 and the control valve for exhaust control 7, as well as the output (pressure) from the pressure sensor P.sub.1, in the case of increasing the set flow.

(5) FIG. 5 A line graph showing changes in the input voltages to the piezoelectric-driven elements of the control valve for pressure control 6 and the control valve for exhaust control 7, as well as the output (pressure) from the pressure sensor P.sub.1, in the case of reducing the set flow.

(6) FIG. 6 A basic configuration diagram of a conventional pressure-type flow controller (FCS-N type).

(7) FIG. 7 Schematic configuration diagrams of conventional pressure-type flow controllers of various forms: (a) shows FCS-N type, (b) shows a pressure-type flow controller (FCS-WR type), (c) shows FCS-SN type, and (d) shows FCS-SWR type.

(8) FIG. 8 A line graph showing an example of the step-down response characteristics of a conventional pressure-type flow controller (FCS-N type) at the time of continuous steps.

(9) FIG. 9 A schematic diagram of a valve mechanism part of a pressure-type flow controller (FCS-N type, FCS-WR type) using a main body with minimized internal volume.

(10) FIG. 10 A line graph showing a flow step-down characteristic curve (from 100% to 0%) of the pressure-type flow controller of FIG. 9 (FCS-N type).

(11) FIG. 11 A systematic configuration diagram of a device for measuring the response characteristics of a pressure-type flow controller provided with an evacuation line.

(12) FIG. 12 Line graphs each showing the results of measuring step-down response characteristics by the response characteristics measuring device of FIG. 11: (a) shows the case where step-down is performed by only the control valve on the supply side, while (b) shows the case where step-down is performed by both control valves on the supply side and the evacuation side.

(13) FIG. 13 Line graphs each showing the results of measuring step-up response characteristics by the response characteristics measuring device of FIG. 11: (a) shows the case where step-up is performed by only the control valve on the supply side, and (b) shows the case where step-up is performed by both control valves on the supply side and the evacuation side.

(14) FIG. 14 Line graphs each showing changes in the input voltage to the piezoelectric elements (not illustrated) for the actuation of the respective control valves CVa and CVb at the time of measuring the step-down characteristics by the response characteristics testing device of FIG. 11: (a) shows the voltages of the control pressure input/output signals of the pressure controller UPC.sub.1 at the time when the evacuation line is not operated, (b) shows the piezoelectric element actuation voltage of the control valve CVa of the pressure regulator UPC.sub.1 at the time when the evacuation line is operated, and (c) shows the piezoelectric element actuation voltage of the control valve CVb of the pressure regulator UPC.sub.2 at the time when the evacuation line is operated.

DESCRIPTION OF EMBODIMENTS

(15) Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(16) FIG. 1 is a longitudinal cross-sectional view showing the basic configuration of the pressure-type flow controller of the present invention, and FIG. 2 is a system diagram showing the configuration of a gas supply box provided with the pressure-type flow controller according to the present invention.

(17) The pressure-type flow controller 1 is composed of a main body 2, a control valve for pressure control 6, a control valve for exhaust control 7, pressure sensors P.sub.1 and P.sub.2, an orifice OL, and the like. The embodiment of FIG. 2 is a pressure-type flow controller of FCS-WR type using one orifice OL.

(18) Incidentally, in FIG. 1, reference sign 2a denotes a valve seat, reference sign 3 denotes an inlet-side block, reference sign 4 denotes a main body block, reference sign 5 denotes an outlet-side block, reference sign 9 denotes a fluid inlet, reference sign 10a denotes a fluid channel, reference sign 10b denotes an exhaust channel, reference sign 10c denotes a channel for leak detection, reference sign 11 denotes a fluid outlet, reference sign 12 denotes an exhaust outlet, reference sign 13 denotes a gasket, reference sign 14 denotes a panel control board for control, reference sign 15 denotes a casing, and reference sign 16 denotes a connector for connection.

(19) The main body 2 comprises the inlet-side block 3, the main body block 4, and the outlet-side block 5 assembled together and integrated by a securing bolt (not illustrated). The control valve for pressure control 6, the control valve for exhaust control 7, the pressure sensors P.sub.1 and P.sub.2, and the like are each screw-fixed to the valve body 2. In addition, the pressure sensor P.sub.2 is communicated to the fluid channel 10a avoiding intersection with the exhaust channel 10b.

(20) The control valve for pressure control 6 is an on/off valve using a piezoelectric-driven element 6a, in which a known metal diaphragm serves as a valve body 20. When energized, the piezoelectric-driven element 6a expands to push a cylindrical body 17 upward against the elasticity of an elastic body 18. As a result, by the elastic force of the metal diaphragm valve body 20, the valve body presser 19 is moved upward, whereby the valve body 20 comes off the valve seat 2a, and the valve is opened. In addition, the degree of valve opening is adjusted by changing the voltage applied to the piezoelectric-driven element 6a.

(21) Incidentally, the operation of the control valve for exhaust control 7 is the same as the operation of the control valve for pressure control 6, and the degree of valve opening is controlled by adjusting the elongation amount of a piezoelectric-driven element 7a.

(22) In addition, as the control valve for exhaust control 7, in place of the piezoelectrically actuated metal-diaphragm-operated on/off valve, it is also possible to use a known pneumatically actuated or electromagnetically actuated on/off valve.

(23) FIG. 2 is a system diagram showing the configuration of a gas supply box to which the pressure-type flow controller according to the present invention is applied. Three kinds of live gas G.sub.1 to G.sub.3 and N.sub.2 gas are supplied to a process chamber 29, each independently, or as a mixture of suitable kinds of gas by a predetermined ratio. Incidentally, as described above, through the control valve for exhaust control 7 (not illustrated), gas in the internal space of FCS-N is forcibly exhausted (evacuated) by a vacuum pump 28 through an outlet-side on/off valve 24 of an exhaust line 27.

(24) Incidentally, in FIG. 2, reference sign 21 denotes a gas supply port, reference sign 22 denotes a supply-side switching valve, reference sign 23 denotes an outlet-side switching valve, and reference sign 26 denotes a mixed gas supply line.

(25) With reference to FIG. 1, in ordinary continuous flow control, the gas flowing in from the fluid inlet 9 is pressure-controlled by the control valve for pressure control 6, and then, through the orifice OL, supplied from the fluid outlet 11 to a predetermined point. In addition, when the controlled flow is to be reduced, for example, stepped down from 100% flow to 50% flow, a switching control signal to 50% flow and a valve opening signal are input from the control board 14 to the control valve for pressure control 6 and the control valve for exhaust control 7, respectively, whereby the control valve for exhaust control 7 is opened. As a result, through the control valve for exhaust control 7, gas between the control valve for pressure control 6 and the orifice OL is forcibly exhausted, and the step-down response time is shortened.

(26) Incidentally, needless to say, by regulating the degree of valve opening of the control valve for exhaust control 7, the step-down time can be controlled.

(27) FIG. 3 shows the step-down response characteristics of the pressure-type flow controller 1 according to this embodiment at the time of continuous steps, which were measured under the same conditions as in the case of FIG. 8.

(28) As is clear from the comparison of Line A and Line B between FIG. 8 and FIG. 3, in the pressure-type flow controller 1 according to this embodiment, the step-down time can be shortened to 0.5 seconds or less.

(29) In addition, by regulating the degree of valve opening of the control valve for exhaust control 7, the step-down time itself can be easily controlled, and also, even when pressure-type flow controllers are operated in different flow ranges, step-down in such several pressure-type flow controllers can be synchronously performed.

(30) Incidentally, FIG. 4 shows changes in the input voltages to the piezoelectric-driven elements of the control valve for pressure control 6 and the control valve for exhaust control 7, as well as the output (pressure) from the pressure sensor P.sub.1, in the case of increasing the set flow. In each case, the step-up time is 0.5 seconds or less, showing that increases in the flow from 20% to 50% and from 50% to 80% can be completed within a step-up time of 0.5 seconds or less.

(31) In addition, inversely to FIG. 4, FIG. 5 shows changes in the input voltages to the piezoelectric-driven elements of the control valve for pressure control 6 and the control valve for exhaust control 7, as well as the output (pressure) from the pressure sensor P.sub.1, in the case of reducing (stepping down) the flow from 80% to 50% and from 50% to 20%. In each case, the step-down time is 0.5 seconds or less.

(32) Incidentally, the embodiment of FIG. 1 has been described based on the pressure-type flow controller of FCS-N type of FIG. 7(b). However, needless to say, the pressure-type flow controller may be any of FCS-N type, FCS-S type, and FCS-SWR type, and the conventional pressure-type flow controller of any type shown in FIG. 7 can be used for the implementation of the present invention.

(33) In addition, the operation principles and configurations of pressure-type flow controllers are already known, and thus the detailed description thereof is omitted herein.

(34) That is, in the pressure-type flow controller 1 according to the present invention, by providing of the evacuation line 27 comprising the control valve for exhaust control 7, the step-down time in flow control can be significantly shortened, and also the step-down time can be easily regulated, leading to the improvement of the so-called gas replaceability of the pressure-type flow controller.

(35) In addition, it also becomes possible to arbitrarily select the width dimension of the main body 2 of the pressure-type flow controller 1. For example, the dimension can be adjusted to the width dimension of a conventional pressure-type flow controller, that is, 92 mm. As a result, the pressure-type flow controller can be used for the repair of conventional facilities.

(36) Further, By making evacuation line blind, such a controller can also be applied as an ordinary pressure-type flow controller. However, there are some problems remaining. For example, an evacuation line 27 is required, the amount of live gas exhausted is increased as a result of forced exhaust, application to an existing gas supply box is difficult, etc.

INDUSTRIAL APPLICABILITY

(37) The present invention can be applied to flow controllers not only for gas supply facilities or gas supply devices for semiconductor manufacturing devices, but also for any gas supply facilities in the chemical industry, the food industry, and the like.

REFERENCE SIGNS LIST

(38) 1: Pressure-type flow controller 2: Main body 2a: Valve seat 3: Inlet-side block 4: Main body block 5: Outlet-side block 6: Control valve for pressure control 6a: Piezoelectric-driven element 7: Control valve for exhaust control 7a: Piezoelectric-driven element 9: Fluid inlet 10a: Fluid channel 10b: Exhaust channel 10c: Channel for leak detection 11: Fluid outlet 12: Exhaust outlet 13: Gasket 14: Panel control board 15: Casing 16: Connector for connection 17: Cylindrical body 18: Elastic body 19: Valve body presser foot 20: Valve body 21: Gas supply port 22: Supply-side switching valve 23: Outlet-side on/off valve 24: Outlet-side on/off valve 26: Mixed gas supply line 27: Evacuation line 28: Vacuum pump 29: Process chamber P.sub.1: Pressure sensor P.sub.2: Pressure sensor OL: Orifice G1 to G3: Live gas