Multi-hole orifice plate for flow control, and flow controller using the same

Abstract

A multi-hole orifice plate for flow control includes an orifice plate for controlling the flow rate of a fluid, wherein the opening area of one orifice necessary for the passage of a predetermined flow rate of fluid is divided to provide a plurality of orifices having a total opening area equal to said opening area.

Claims

1. A multi-hole orifice plate for flow control used in a pressure-controlled flow controller comprising a control valve and a pressure detector, the multi-hole orifice plate having a plurality of orifices, wherein the plurality of orifices have a total opening area corresponding to an opening area of a single orifice necessary for the passage of a gas at a rated or full scale flow rate of the pressure-controlled flow controller; and wherein the multi-hole orifice plate has a thickness of 20 to 200 μm, the plurality of orifices each have a bore of 0.010 to 0.200 mm, the number of the plurality of orifices is 2 to 100, and the plurality of orifices are formed by pressing.

2. The multi-hole orifice plate for flow control according to claim 1, wherein the plurality of orifices each have a longitudinal plane shape including a rectangular part and a trapezoidal part.

3. The multi-hole orifice plate for flow control according to claim 2, wherein a portion on the back side of the orifice plate having the plurality of orifices bored has a polished finishing surface.

4. The multi-hole orifice plate for flow control according to claim 1, wherein when the ratio P.sub.2/P.sub.1 between the pressure (P.sub.1) upstream of the orifice plate and the pressure (P.sub.2) downstream of the orifice plate is equal to or lower than the pressure ratio at which the critical expansion conditions of a gas are established, the gas flow rate changes in direct proportion to the gas pressure (P.sub.1) upstream of the orifice plate.

5. A pressure-controlled flow controller using an orifice plate, wherein the orifice plate is the multi-hole orifice plate for flow control according to claim 1.

6. A pressure-controlled flow controller using an orifice plate, wherein the orifice plate is the multi-hole orifice plate for flow control according to claim 2.

7. A pressure-controlled flow controller using an orifice plate, wherein the orifice plate is the multi-hole orifice plate for flow control according to claim 3.

8. A pressure-controlled flow controller using an orifice plate, wherein the orifice plate is the multi-hole orifice plate for flow control according to claim 4.

9. The multi-hole orifice plate for flow control according to claim 1, wherein the plurality of orifices each have the bore of 0.079 to 0.200 mm, and the number of the plurality of orifices is 2 to 37.

10. The multi-hole orifice plate for flow control according to claim 1, wherein the plurality of orifices each have the bore of 0.079 to 0.135 mm, and the number of the plurality of orifices is 5 to 37.

11. The multi-hole orifice plate for flow control according to claim 1, wherein the plurality of orifices each have different diameters on one side of the orifice plate and the other side of the orifice plate.

12. The multi-hole orifice plate for flow control according to claim 1, wherein the plurality of orifices have same circular shapes and diameters.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a system diagram of a testing device used for testing the orifice flow characteristics.

(2) FIG. 2 is a line chart showing the relation between pressure ratio P.sub.2/P.sub.1 and set point error (S.P. %) of a pressure-controlled flow controller with F.S. 130 sccm.

(3) FIG. 3 is a line chart similar to FIG. 2 with F.S. 850 sccm.

(4) FIG. 4 is a line chart similar to FIG. 2 with F.S. 1600 sccm.

(5) FIG. 5 is a line chart showing the relation between the set flow rate (%) at a pressure ratio P.sub.2/P.sub.1 at which the set point error S.P. % is within ±1% and the error relative to full scale (linearity error) (F.S. %), with respect to a pressure-controlled flow controller with F.S. 130 sccm.

(6) FIG. 6 is a line chart similar to FIG. 5 with F.S. 850 sccm.

(7) FIG. 7 is a line chart similar to FIG. 5 with F.S. 1600 sccm.

(8) FIG. 8A shows a plane view of an example of the multi-hole orifice plate according to the present invention, FIG. 8B shows a back view of FIG. 8A, and FIG. 8C shows a c-c sectional view of FIG. 8B.

(9) FIG. 9A is a plan view showing another example of the multi-hole orifice plate according to the present invention, FIG. 9B shows a back view of FIG. 9A and FIG. 9C shows a sectional view of FIG. 9B.

(10) FIG. 10 is a plan view showing another example of the multi-hole orifice plate according to the present invention.

(11) FIG. 11 is a line chart showing relation between the pressure ratio P.sub.2/P.sub.1 and the set point error (S.P. %) similar to FIG. 2 to FIG. 4 in the case of using the multi-hole orifice plate of FIG. 10.

(12) FIG. 12 is a line chart showing relation between the set flow rate (%) and the linearity error (F.S. %) similar to FIG. 5 to FIG. 7 in the case of using the multi-hole orifice plate of FIG. 10.

(13) FIG. 13 is a block diagram of a known pressure-controlled flow controller.

(14) FIG. 14 is a line chart showing the flow control characteristics of the pressure-controlled flow controller of FIG. 13.

DESCRIPTION OF EMBODIMENTS

(15) Hereinafter, the present invention will be described based on embodiments and drawings.

(16) FIG. 8A, FIG. 8B, and FIG. 8C show an example of the orifice plate for flow control according to the present invention; FIG. 8A is a plan view, FIG. 8B is a back view, and FIG. 8C is a c-c sectional view.

(17) In FIG. 8A, a total of fifteen orifices 12 with a diameter of 0.085 mm are provided in an orifice plate 7a with an outer diameter of 3.5 mm and a thickness of 0.05 mm.

(18) In addition, the longitudinal plane shape of the orifice 12 is formed by pressing to have a rectangular part 12a and a trapezoidal part 12b as shown in FIG. 8C, and the depth of the orifice 12 is 0.05 mm, which is the same as the thickness of the orifice plate 7a.

(19) Furthermore, the portion on the back side of the orifice plate 7a, where the orifices 12 are provided, is polished in a narrow shape to form a polished surface 12c, and the front and back of the orifice plate 7a are distinguished by the polished surface 12c.

(20) FIG. 9A, FIG. 9B, and FIG. 9C shows another example of the multi-hole orifice plate 7a for flow control according to the present invention, which is the same as the multi-hole orifice plate for flow control of FIG. 8A, FIG. 8B, and FIG. 8C, except that the number of orifices 12 is 5, and the orifices 12 each has a diameter of 0.135 mm.

(21) FIG. 10 is an enlarged plan view showing another example of the multi-hole orifice plate 7a for flow control according to the present invention, in which thirty-seven orifices 12 each having a diameter φ of 79 μm (0.079 mm) are provided.

(22) The outer diameter, the thickness, and the like of the orifice plate 7a are the same as those of the orifice plates 7a of FIG. 8A and FIG. 9A.

(23) The diameter φ of 79 μm of the orifice 12 is equal to the diameter of the orifice of a single-hole orifice plate 7 of Pressure-Controlled Flow Controller F180 manufactured by Fujikin Incorporated, which is a control orifice plate with a rated flow rate of 180 sccm (F.S.).

(24) Accordingly, the F.S. flow rate of the multi-hole orifice plate 7a for flow control of FIG. 10 is equivalent to 180 sccm×37=6.660 sccm.

(25) FIG. 11 shows a curve similar to FIG. 2, showing the relation with the pressure ratio P.sub.2/P.sub.1, wherein the single-hole orifice plate 7 of the tester of FIG. 1 is replaced by the multi-hole orifice plate 7a of FIG. 10.

(26) As is clear from the comparison between FIG. 11 and FIG. 2, in the case of the multi-hole orifice plate 7a of the present invention, the pressure ratio P.sub.2/P.sub.1 value at which the set point error (S.P. %) is within a range of ±1% does not fall below 0.45 even at the time of 10% input (10% of the set flow rate). At the time of 100% input (100% of the set flow rate), the P.sub.2/P.sub.1 value of about 0.52 can be obtained.

(27) In contrast, in FIG. 3 in which the maximum flow rate is 850 sccm, the pressure ratio P.sub.2/P.sub.1 at the time of 100% input is about 0.42. Even in FIG. 4 in which the maximum flow rate is 1600 sccm, the pressure ratio P.sub.2/P.sub.1 at the time of 100% input is about 0.40. This shows that in the case where the multi-hole orifice plate 7a of the invention of the present application is used, the range of P.sub.2/P.sub.1 whereat critical expansion conditions are established can be expanded. In addition, the reason why the theoretical pressure ratio P.sub.2/P.sub.1 whereat critical expansion conditions are established is slightly different from the pressure ratio P.sub.2/P.sub.1 at which critical expansion conditions are established in actual measurement as above has not been theoretically analyzed yet and is currently under examination. However, it is assumed that it is affected by differences in the flowing condition of the fluid on the orifice outlet side.

(28) FIG. 12 is a line chart similar to FIG. 5 in the case of using the multi-hole orifice plate 7a of the present invention. The line chart shows the relation between the set flow rate (%) at a pressure ratio P.sub.2/P.sub.1 whereat the set point error (S.P. %) is within ±1% and the error relative to the control flow at the time of 100% setting (flow linear error) (F.S. %).

(29) As clearly shown in FIG. 12, it has been confirmed that the multi-hole orifice plate 7a of the present invention also results in a flow linear error (F.S. %) within ±1% F.S.

(30) In addition, the pressure-controlled flow controller according to the present invention is given by replacing the orifice plate of the Pressure-Controlled Flow Controller F180 manufactured by Fujikin Incorporated, the pressure-controlled flow controller shown in FIG. 13, or the like with the orifice plate of the present invention. Thus, the detailed description will be omitted.

(31) As described above, in the multi-hole orifice plate for flow control and the pressure-controlled flow controller using the same according to the present invention, by adjusting the number of orifices 12 based on the controlled flow rate even when the controlled flow rate increases, the range of the pressure ratio P.sub.2/P.sub.1 at which critical expansion conditions are established can be maintained wide and constant, thereby making it possible to perform high-precision flow control stably over a wide range.

INDUSTRIAL APPLICABILITY

(32) The multi-hole orifice plate according to the present invention can be applied not only to a pressure-controlled flow controller but also to any orifices in ordinary orifice devices inserted into a pipeline to control the fluid flow, fluid diverters, etc.

REFERENCE SIGNS LIST

(33) 1: Gas inlet 2: Pressure regulator 3: Pressure meter 4: Molblock flow meter 5: Pressure-type flow controller 6: Control valve 7: Orifice plate (single-hole) 7a: Multi-hole orifice plate 8: Pressure detector on the orifice upstream side 9: Pressure detector on the orifice downstream side 10: Regulation valve for the pressure P.sub.2 on the orifice downstream side 11: Evacuation pump P.sub.1: Pressure on the orifice upstream side P.sub.2: Pressure on the orifice downstream side P.sub.O: Pressure on the gas supply source side 12: Orifice