CN102096420B - Mass flow controller - Google Patents
Mass flow controller Download PDFInfo
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- CN102096420B CN102096420B CN200910258576.7A CN200910258576A CN102096420B CN 102096420 B CN102096420 B CN 102096420B CN 200910258576 A CN200910258576 A CN 200910258576A CN 102096420 B CN102096420 B CN 102096420B
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- coefficient
- flow
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- side pressure
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D7/00—Control of flow
- G05D7/06—Control of flow characterised by the use of electric means
- G05D7/0617—Control of flow characterised by the use of electric means specially adapted for fluid materials
- G05D7/0629—Control of flow characterised by the use of electric means specially adapted for fluid materials characterised by the type of regulator means
- G05D7/0635—Control of flow characterised by the use of electric means specially adapted for fluid materials characterised by the type of regulator means by action on throttling means
Abstract
The invention ensures that PI (Proportion Integration) performance of a mass flow controller is improved. In the mass flow controller, based on at least two of a primary side pressure, an ageing variable of the primary side pressure, and a flow set value, a proportional coefficient, an integral coefficient and a differential coefficient in a PID (Proportion Integration Differentiation) operation under a stabilizing state are changed.
Description
Technical field
The present invention relates to a kind of mass flow controller (mass flow controller) that the flow of the fluid of gas (gas) or liquid etc. is controlled.
Background technology
Such as, when the various gases etc. for the manufacture of semiconductor are supplied to semiconductor-fabricating device, mass flow controller are set respectively in the supply line of these gases etc., come whereby to regulate respectively gas flow.And previously on each mass flow controller, series connection attached pressure governor (pressure regulator) respectively, made pressure in the stream of each mass flow controller that extreme variation can not occur, thus made flow control become easy.
The flow control mode of described mass flow controller is proportion integration differentiation (Proportional Integral Derivative substantially, PID) control, such as, as Patent Document 1, known under transitional responsive state and steady state (SS), PID coefficient is switched and carries out FEEDBACK CONTROL (feedback control).
Specifically, technology shown in patent documentation 1 is the value that flow setting value is substituting to gained in the function of regulation by use, be used as the yield value (gain value) be multiplied with the deviation in scale operation, the flow setting value such as substituted into is less, then the value of the function of the described regulation used under the steady state (SS) calculated is less.That is, the previous mass flow controller shown in patent documentation 1 is only that scale-up factor, integral coefficient and differential coefficient (below also referred to as PID coefficient) under steady state (SS) are only changed pro rata with flow setting value.
But subject application inventor obtains following experimental result: at steady state, when primary side pressure (valve inlet pressure) rises with when declining, the optimum value of PID coefficient is different; Even if the time dependent variable quantity of primary side pressure is identical, if the primary side pressure before change is different, so PID coefficient is still different; And flow setting value and PID coefficient optimum value there is no linear relationship.So understand at steady state, if only make PID coefficient and flow setting value proportional, so there is the limit in the raising of pressure insensitiveness (Pressure Insensitive, PI) performance.
Patent documentation: Japanese Patent Laid-Open 2007-34550 publication
Summary of the invention
Therefore, the present invention is developed into solve described problem points at one stroke, and its main expection problem is that the PI performance making mass flow controller improves further.
That is, the feature of mass flow controller of the present invention is to comprise: flow sensor (sensor) portion, measures the flow of the fluid flowed in stream, and exports the flow measurement signal of the measured value representing this flow; Flowrate control valve, is arranged on upstream side or the downstream in described flow sensor portion; Calculating part, the flow measurement value represented by described flow measurement signal and the deviation of desired value and flow setting value implement PID arithmetic, to calculate the feedback control value exporting flowrate control valve to; And opening control signal efferent, produce opening control signal based on described feedback control value, and export flowrate control valve to; Described calculating part based at least two in the time dependent variable quantity of primary side pressure, this primary side pressure and described flow setting value, to changing for the scale-up factor in PID arithmetic, integral coefficient and differential coefficient under steady state (SS).
According to mass flow controller as above, due to based on primary side pressure, at least two in the time dependent variable quantity of this primary side pressure and described flow setting value, come under steady state (SS) for the scale-up factor in PID arithmetic, integral coefficient and differential coefficient change, therefore, scale-up factor is made by flow setting value with previous, the method that integral coefficient and differential coefficient change pro rata is compared, more suitably scale-up factor can be obtained, integral coefficient and differential coefficient, result, be not vulnerable to the impact of the pressure variation of primary side pressure, stable flow control can be carried out.
Particularly at steady state, when primary side pressure increase with when declining, the optimum value of scale-up factor, integral coefficient and differential coefficient is different, therefore, comparatively ideal, described calculating part according to the time dependent variable quantity of primary side pressure positive and negative come comparative example coefficient, integral coefficient and differential coefficient change.
In order to make scale-up factor, integral coefficient and differential coefficient become optimum value, be not vulnerable to the impact of the pressure variation of primary side pressure, to go forward side by side the flow control of line stabilization, comparatively ideally be, described calculating part is positive and negative according to the time dependent variable quantity of primary side pressure, comparative example coefficient, integral coefficient and differential coefficient change, then, use the value obtained in function flow setting value being substituting to regulation to carry out regulation computing, come the scale-up factor through changing whereby, integral coefficient and differential coefficient change, then, use the value being substituting to by primary side pressure and obtaining in the function of regulation to carry out regulation computing, come the scale-up factor through changing whereby, integral coefficient and differential coefficient change.
[effect of invention]
According to the present invention formed in this way, the PI performance of mass flow controller can be made to improve.
Accompanying drawing explanation
Fig. 1 is the overall schematic of the mass flow controller of one embodiment of the present invention.
Fig. 2 is the pie graph of the flow control system of the mass flow controller using this embodiment.
Fig. 3 is the functional block diagram of the control part in this embodiment.
Fig. 4 is the process flow diagram of the PID coefficient change order represented in this embodiment.
Fig. 5 (a), Fig. 5 (b) are the schematic diagram of the function represented for changing PID coefficient.
[explanation of symbol]
1 stream 2 flow sensor portion
3 flowrate control valve 4 pressure transducer portions
5 control part 6 signal receiving parts
7 calculating part 8 opening control signal efferents
9 flow output 71 deviation calculating parts
72 controlling value calculating part 100 mass flow controllers
B fluid feed sources F fluid
FV air pressure valve P1 introducing port
P2 export mouth PR pressure governor
S1, S2, S3, S4, S5, S6 step
Embodiment
Below, be described with reference to the embodiment of accompanying drawing to mass flowmeter 100 of the present invention.In addition, Fig. 1 is the overall schematic of the mass flow controller of present embodiment, Fig. 2 is the pie graph of the flow control system (system) of service property (quality) flow controller, Fig. 3 is the functional block diagram of control part, Fig. 4 is the process flow diagram (flow chart) representing PID coefficient change order, and Fig. 5 is the schematic diagram of the function represented for changing PID coefficient.
< device forms >
As shown in Figure 1, the mass flow controller 100 of present embodiment comprises: internal flow path 1; Flow sensor portion 2, measures the flow of the fluid F of flowing in described internal flow path 1; Flowrate control valve 3, is arranged on the such as downstream in described flow sensor portion 2; Pressure transducer portion 4, is arranged on the upstream side of described flow sensor portion 2 and flowrate control valve 3; And control part 5; And such as shown in Fig. 2, this mass flow controller 100 is used in gas supply system, this gas supply system, in manufacture of semiconductor (process), provides gas tangentially to chamber (chamber).
Below each several part is described, in the upstream-end opening of internal flow path 1 to form introducing port (port) P1, in the downstream-end opening of this internal flow path 1 to form export mouth P2, such as, introducing port P1 is connected with the fluid feed sources B of gas bomb (bomb) etc. via outside pipe arrangement, and export mouth P2 is connected with the chamber (not shown) in order to manufacture semiconductor via outside pipe arrangement.In addition, in this embodiment, as shown in Figure 2, branch out multiple pipe arrangement from a fluid feed sources B, each pipe arrangement arranges mass flow controller 100 respectively.Further, pressure governor PR is only arranged on the outlet of fluid feed sources B, on each pipe arrangement, do not arrange the pressure governor of mass flow controller 100 respectively.In addition, symbol FV is air pressure valve.
Although the detailed content in non-flow sensor portion 2 illustrates, but this flow sensor portion 2 such as comprises a pair thermal sensor (thermal sensor) be arranged on stream 1, by this thermal sensor, the instantaneous delivery of fluid F is detected as electric signal, and by internal electronics by this electric signal amplification etc., then export the flow measurement signal with the value corresponding with detecting flow.
Although do not illustrate the detailed content of flowrate control valve 3 equally, but the actuator (actuator) of this flowrate control valve 3 such as by comprising piezoelectric element (piezoelectric element) makes valve opening change, and described actuator is driven from the electric signal of outside and opening control signal by receiving, valve opening is adjusted to the valve opening corresponding with the value of this opening control signal, thus the flow of convection cell F controls.
Although do not illustrate the detailed content in pressure transducer portion 4, the pressure-active element (pressure sensitive element) that this pressure transducer portion 4 such as comprises diaphragm (diaphragm) (stainless steel diaphragm (stainless diaphragm) or silicon diaphragm (silicon diaphragm) etc.) and measures the displacement of this diaphragm, be electric signal by this pressure-active element by the displacement detecting of diaphragm, by internal electronics by this electric signal amplification etc., then the piezometry signal with the value corresponding with detecting flow is exported.
Control part 5 is by having central processing unit (Central Processing Unit, CPU), storer (memory), analog/digital converter, digital/analog converter etc. numeral (digital) or simulation (analog) electronic circuit formed, this control part 5 can be special control part, also can use the general-purpose computer of PC (personal computer) etc. in part or all.In addition, this control part 5 can not use CPU but only utilize mimic channel to play the function of described each several part, also can form by by the wired or wireless multiple equipment be connected to each other, and be integrated without the need to becoming in physical property.
In addition, regulated procedure (program) is stored in which memory, the collaborative running of the peripheral equipment of CPU or this CPU is made according to this program, whereby, as shown in Figure 3, described control part 5 at least plays the function as signal receiving part 6, calculating part 7, opening control signal efferent 8 and flow output 9.
The piezometry signal that signal receiving part 6 receives the flow measurement signal sent from flow sensor portion 2, the flow setting signal inputted from other computers etc. etc. and sends from pressure transducer portion 4, and the value of these signals is stored to the regulation region in such as storer.
Calculating part 7 comprises: deviation calculating part 71, obtains the flow measurement value represented by described flow measurement signal, and calculates the deviation of the flow setting value represented by this flow measurement value and desired value and described flow setting signal; And controlling value calculating part 72, PID arithmetic is implemented to described deviation and calculates the feedback control value being applied to flowrate control valve 3.
Opening control signal efferent 8 produces the opening control signal of the value had based on described feedback control value, and exports this opening control signal to flowrate control valve 3.
Flow output 9 is implemented the computing of regulation to described flow measurement value and calculates flowmeter indicating value, and represents that signal (simulating signal or digital signal) is exported in the mode that can be utilized in outside by having the flow that this flowmeter indicating value is used as value.
And, in this embodiment, controlling value calculating part 72 is based on the time dependent variable quantity of primary side pressure (supply pressure), this primary side pressure and described flow setting value, to changing for the scale-up factor (P) in PID arithmetic, integral coefficient (I) and differential coefficient (D) (that is, the PID coefficient used in the PID control procedure of steady state (SS)) under the state (steady state (SS)) of flow steady flow.Herein, state during so-called steady state (SS) refers to except During (such as about two seconds), flow setting value changes hardly, and described During is the specified time limit counted from the time point making flow setting value change more than ormal weight or ormal weight within the unit interval.In addition, according to the percent value meter relative to full scale value (full scale), so-called ormal weight refers to about 0 ~ 10%, preferably 0.3% ~ 5%.In addition, so-called specified time limit is specifically 0 second ~ about 10 seconds about referring to the several seconds, preferably 0.3 second ~ 5 seconds.
More specifically, controlling value calculating part 72 is positive and negative according to the time dependent variable quantity of primary side pressure (pressure of the upstream side of mass flow controller), comparative example coefficient, integral coefficient and differential coefficient (below also referred to as PID coefficient) change, then, use function flow setting value being substituting to regulation and the value obtained to carry out computing, come whereby to change the PID coefficient through changing, then, using the value being substituting to by primary side pressure and obtaining in the function of regulation to carry out computing, coming whereby to change the PID coefficient through changing.And, controlling value calculating part 72 is positive and negative according to the time dependent variable quantity of primary side pressure, that is, according to the situation of dp/dt > 0 and the situation of dp/dt≤0, the function change that the function making flow setting value intrinsic changes and makes primary side pressure intrinsic.
Below, be described with reference to the concrete variation of Fig. 4 to controlling value calculating part 72.
First, controlling value calculating part 72 obtains the piezometry signal of the primary side pressure obtained by pressure transducer portion 4, calculates the time dependent variable quantity of primary side pressure and this primary side pressure.
Then, the positive and negative of time dependent variable quantity of controlling value calculating part 72 pairs of primary side pressure judges (step (step) S1).When the time dependent variable quantity judging primary side pressure is for just (dp/dt > 0), namely, when primary side pressure increase, controlling value calculating part 72 by following mathematical expression, and changes (step S2) PID coefficient based on flow setting value.
P′＝P×Fu(set)(1)
I′＝I×Fu(set)(2)
D′＝D×Fu(set)(3)
Herein, Fu () is that namely the intrinsic function of flow setting value sets coefficient function, and set represents flow setting value.As shown in Fig. 5 (a), the setting coefficient function Fu of present embodiment is the proportionality constant of 0-50% and the different polygronal function of proportionality constant of 50% ~ 100%.Broken line shape is not limited to this, can suitably set this broken line shape.In addition, this setting coefficient function Fu can be set to curvilinear function, but there is calculation process amount and increase and be difficult to problem that PID coefficient is adjusted.
Then, controlling value calculating part 72 by following mathematical expression, and is changed (step S3) the P ' I ' D ' coefficient obtained by described (1) ~ (3) based on primary side pressure.
P″＝P′×Gu(p)(4)
I″＝I′×Gu(p)(5)
D″＝D′×Gu(p)(6)
Herein, Gu () is the intrinsic function of primary side pressure and pressure coefficient function, and p represents primary side force value.As shown in Fig. 5 (a), the pressure coefficient function of present embodiment is the proportion function calculated the value with inputted primary side proportional pressure.In addition, also this pressure coefficient function G u can be set to polygronal function or curvilinear function.When this pressure coefficient function G u is set to curvilinear function, there is calculation process amount and increase and be difficult to problem that PID coefficient is adjusted.
According to above content, when the time dependent variable quantity of primary side pressure is timing, P, I, D to be changed to P ", I ", D based on flow setting value and primary side pressure by controlling value calculating part 72 "; and (scale-up factor P ", integral coefficient I " and differential coefficient D ") comes to implement PID arithmetic, to calculate feedback control value (step S4) to deviation to use this PID coefficient.
On the other hand, controlling value calculating part 72 when judging that the variable quantity of primary side pressure is negative, that is, when primary side pressure drop, by following mathematical expression, and changes (step S5) PID coefficient based on flow setting value.
P′＝P×Fd(set)(7)
I′＝I×Fd(set)(8)
D′＝D×Fd(set)(9)
Herein, Fd () is that namely the intrinsic function of flow setting value sets coefficient function, and set represents flow setting value.As shown in Fig. 5 (b), this setting coefficient function Fd is the polygronal function identical with described setting coefficient function Fu, but flex point (bending point) and proportionality constant different.In addition, this setting coefficient function Fd can be set to curvilinear function, but there is calculation process amount and increase and be difficult to problem that PID coefficient is adjusted.
Secondly, controlling value calculating part 72 by following mathematical expression, and is changed (step S6) the P ' I ' D ' coefficient obtained by described (7) ~ (9) based on primary side pressure.
P″＝P′×Gd(p)(10)
I″＝I′×Gd(p)(11)
D″＝D′×Gd(p)(12)
Herein, Gd () is the intrinsic function of primary side pressure and pressure coefficient function, and p represents primary side force value.As shown in Fig. 5 (b), this pressure coefficient function G d is the proportion function identical with described pressure coefficient function F d, but proportionality constant is different from the proportionality constant of described pressure coefficient function F d.In addition, also this pressure coefficient function G d can be set to polygronal function or curvilinear function.When this pressure coefficient function G d is set to curvilinear function, there is calculation process amount and increase and be difficult to problem that PID coefficient is adjusted.
According to above content, when the time dependent variable quantity of primary side pressure is for time negative, P, I, D to be changed to P ", I ", D based on flow setting value and primary side pressure by controlling value calculating part 72 "; and (scale-up factor P ", integral coefficient I " and differential coefficient D ") comes to implement PID arithmetic, to calculate feedback control value (step S4) to deviation to use this PID coefficient.
The effect > of < present embodiment
According to the mass flow controller 100 of the present embodiment formed in this way, due to based on primary side pressure, the time dependent variable quantity of this primary side pressure and described flow setting value, come under steady state (SS) for the scale-up factor in PID arithmetic, integral coefficient and differential coefficient change, therefore, scale-up factor is made by flow setting value with previous, the method that integral coefficient and differential coefficient change pro rata is compared, more suitably scale-up factor can be obtained, integral coefficient and differential coefficient, result, be not vulnerable to the impact of the pressure variation of primary side pressure, stable flow control can be carried out.
Other variant embodiment of < >
In addition, the present invention is not limited to described embodiment.In the following description, identical symbol is enclosed to the component corresponding with described embodiment.
Such as, in said embodiment, based on the time dependent variable quantity of primary side pressure, this primary side pressure and the whole of described flow setting value, PID coefficient is changed, but the combination of the combination of the time dependent variable quantity of two in described three such as primary side pressure and these primary side pressure or primary side pressure versus flow setting value etc. also can be used to change.
And, in said embodiment, the change order of PID coefficient is the order of " the time dependent variable quantity according to primary side pressure changes " → " changing according to flow setting value " → " changing according to primary side pressure ", but be not limited to this order, also can be other combinations.
In addition, also operation valve can be arranged on the upstream side in flow sensor portion, flow sensor portion is not limited to described thermal sensor, also can be the sensor of other flow measurement modes of differential pressure pick-up (differential pressuresensor) etc.
In addition, can by addition appropriately combined for part or all of described embodiment or variant embodiment, certain the present invention is not limited to described embodiment, can carry out various distortion without departing from the spirit and scope of the invention.
Claims (3)
1. a mass flow controller, is characterized in that comprising:
Flow sensor portion, measures the flow of the fluid flowed in stream, and exports the flow measurement signal of the measured value representing this flow;
Flowrate control valve, is arranged on upstream side or the downstream in described flow sensor portion;
Calculating part, the flow measurement value represented by described flow measurement signal and the deviation of desired value and flow setting value implement PID arithmetic, to calculate the feedback control value exporting flowrate control valve to; And
Opening control signal efferent, produces opening control signal based on described feedback control value, and exports flowrate control valve to;
Described calculating part based on the time dependent variable quantity of primary side pressure and this primary side pressure, to changing for the scale-up factor in PID arithmetic, integral coefficient and differential coefficient under steady state (SS).
2. mass flow controller according to claim 1, is characterized in that:
Described calculating part according to the time dependent variable quantity of primary side pressure positive and negative come comparative example coefficient, integral coefficient and differential coefficient change.
3. mass flow controller according to claim 1, is characterized in that:
Described calculating part is positive and negative according to the time dependent variable quantity of primary side pressure, comparative example coefficient, integral coefficient and differential coefficient change, then, use the value obtained in function flow setting value being substituting to regulation to carry out regulation computing, come whereby to change the scale-up factor through changing, integral coefficient and differential coefficient, then, using the value being substituting to by primary side pressure and obtaining in the function of regulation to carry out regulation computing, coming whereby to change the scale-up factor through changing, integral coefficient and differential coefficient.
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| CN200910258576.7A CN102096420B (en) | 2009-12-15 | 2009-12-15 | Mass flow controller |
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| JP6520945B2 (en) * | 2014-07-15 | 2019-05-29 | 日立金属株式会社 | Method of controlling flow rate of fluid, mass flow control device for executing the method, and mass flow control system using the mass flow control device |
| CN104500811A (en) * | 2014-12-10 | 2015-04-08 | 西南铝业（集团）有限责任公司 | Emulsion flow rate control system |
| CN105116931A (en) * | 2015-07-21 | 2015-12-02 | 首钢京唐钢铁联合有限责任公司 | Hydrogen control method and hydrogen control system for hydrogen-nitrogen mixing station |
| US10365666B2 (en) * | 2015-09-11 | 2019-07-30 | Hitachi Metals, Ltd. | Mass flow controller |
| US11144075B2 (en) | 2016-06-30 | 2021-10-12 | Ichor Systems, Inc. | Flow control system, method, and apparatus |
| US10838437B2 (en) | 2018-02-22 | 2020-11-17 | Ichor Systems, Inc. | Apparatus for splitting flow of process gas and method of operating same |
| CN106774468B (en) * | 2016-12-27 | 2019-11-08 | 中国航天空气动力技术研究院 | Flow rate controlling method |
| JP2021189514A (en) * | 2020-05-26 | 2021-12-13 | アズビル株式会社 | Mass flow controller and hunting suppressing method |
| KR20230150309A (en) | 2021-03-03 | 2023-10-30 | 아이커 시스템즈, 인크. | Fluid flow control system including manifold assembly |
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