KR20180091764A - Maintenance time predicting apparatus, flow rate controlling apparatus, and maintenance time predicting method - Google Patents

Abstract

The objective of the present invention is to predict a time when the maintenance for a flow rate control apparatus and a related apparatus thereof is necessary. A maintenance time prediction apparatus comprises: a valve opening obtaining unit (3) for obtaining opening of a valve when a flow rate of a fluid is maintained to a predefined target flow rate during a flow rate control which controls the flow rate of the fluid by using the valve; and an uncontrollable time estimating unit (4) for estimating a time until the flow rate of the fluid becomes an uncontrollable state which cannot maintain the flow rate of the fluid as the target flow rate based on a change of the opening of the valve obtained at predetermined time intervals and a function approximating a relation between the opening of the valve and the flow rate of the fluid.

Description

Technical Field [0001] The present invention relates to a maintenance time predicting device, a flow rate control device, and a maintenance time predicting method,

The present invention relates to a technique for predicting a time when maintenance is required for a flow control device such as a mass flow controller and related devices such as a filter.

In a semiconductor manufacturing apparatus or the like, a flow rate control device such as a mass flow controller as shown in Fig. 7 is employed to introduce a material gas or the like into the vacuum chamber at a constant flow rate (see Patent Document 1). Reference numeral 102 denotes a head portion of the sensor package 101. Reference numeral 103 denotes a fluid sensor mounted on the head portion 102. Reference numeral 104 denotes a fluid sensor mounted on the head portion 102. Reference numeral 100 denotes a main body block, Reference numeral 105 denotes an opening at the inlet side of the flow path 105, and reference numeral 107 denotes an opening at the outlet side of the flow path 105. As shown in Fig.

Fluid flows from the opening 106 into the flow path 105 and through the valve 104 and out of the opening 107. The fluid sensor 103 measures the flow rate of the fluid flowing through the flow path 105. A control circuit (not shown) of the mass flow controller drives the valve 104 so that the flow rate of the fluid measured by the fluid sensor 103 coincides with the set value.

While continuing to control the flow rate of the material gas by the mass flow controller, it is possible to prevent dust from adhering to the mass flow controller itself or related equipment such as a filter provided in the flow path of the material gas due to influence of components included in the material gas Or the like may occur.

Therefore, there has been proposed an apparatus for correcting the valve opening degree by manipulating the valve opening so that a flow error or a pressure error does not occur only within the allowable accuracy range over the entire measurement range of the fluid sensor incorporated in the mass flow controller (see Patent Document 2) .

However, in the diagnostic apparatus disclosed in Patent Document 2, it is possible to diagnose whether or not the error between the measured value of the fluid sensor and the actual flow rate is an allowable level in the accurate drawing. However, when the maintenance such as calibration There is a problem that it can not be predicted whether or not it will be. In the semiconductor manufacturing apparatuses and the like, since the maintenance is easily predicted by the maintenance timing, improvement is required.

Japanese Patent Application Laid-Open No. 2008-039588 Japanese Patent No. 5931668

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a maintenance time predicting device, a flow rate control device, and a maintenance time predicting method capable of predicting a time required for maintenance of a flow rate control device and its related devices .

The maintenance time predicting device of the present invention is a device for predicting a maintenance time of a fluid that is controlled by a valve, The flow rate of the fluid can be maintained at the target flow rate based on a function approximating the relationship between the opening of the valve and the flow rate of the fluid and the change in the degree of opening of the valve acquired at a predefined time interval And an unrecoverable control time estimator configured to estimate a time until a non-allowable control state is obtained.

Further, in an exemplary configuration of the maintenance time predicting apparatus of the present invention, the incommunicable control time estimating section may calculate a time until the opening degree of the valve acquired by the valve opening degree acquiring section reaches the upper limit, And estimates the time as a time until the control state is obtained.

Further, in one configuration example of the maintenance time predicting apparatus of the present invention, the function is defined by at least a term relating to the degree of opening of the valve and a gain which is a value multiplied by the term, Wherein the control unit determines whether or not the gain is decremented with the elapse of time based on a formula obtained from the function and a change in the degree of opening of the valve acquired by the valve opening degree acquisition unit And estimates the time of the time difference.

Further, in one configuration example of the maintenance time predicting apparatus of the present invention, the function is a function approximating a nonlinear relationship between the opening of the valve and the flow rate of the fluid, and the term relating to the opening degree of the valve is represented by an exponential function .

Further, in one example of the maintenance time predicting apparatus of the present invention, the function is a function approximating a nonlinear relationship between the opening of the valve and the flow rate of the fluid, and the term relating to the degree of opening of the valve is represented by a fraction function .

In addition, in the construction example of the maintenance time predicting apparatus of the present invention, it is preferable that the inactivity-free time estimating unit estimates the inactivity-free state by the valve opening degree acquiring unit A first gain calculating section that calculates the gain at the past time point based on the obtained degree of opening of the valve, and a second gain calculating section that calculates, based on the degree of opening of the valve acquired by the valve opening degree acquiring section at present, Based on the target flow rate, a gain obtained when the degree of opening of the valve acquired by the valve opening degree acquiring section at a point in time before the current point reaches the upper limit, A third gain calculator for calculating a gain based on the gain calculated by the first, second and third gain calculators and a time from the past time point to the present time point; W, is characterized in that the time composed of a calculator for calculating the amount of time before which the non-control state.

Further, an exemplary configuration of the maintenance time predicting apparatus of the present invention is characterized by further comprising: an estimation result outputting section for numerically displaying the time estimated by the incoherent control time estimating section.

Further, an example of the configuration of the maintenance time predicting apparatus of the present invention further includes an estimation result output unit that issues an alarm when the time estimated by the incapable control time estimating unit becomes less than a predetermined threshold time .

The flow rate control device of the present invention further includes a flow rate measuring section for measuring a flow rate of the fluid flowing through the flow path, a valve provided in the flow path, and a valve control section for controlling the flow rate of the fluid, And a maintenance time predicting device, wherein the valve opening degree acquiring section of the maintenance time predicting device acquires an opening degree of the valve installed in the flow path.

The maintenance time predicting method of the present invention is a method for predicting a maintenance time of a fluid in which a flow rate of a fluid is controlled by using a valve, And a controller for controlling the flow rate of the fluid to be maintained at the target flow rate based on a predetermined function approximating a relationship between the opening of the valve and the flow rate of the fluid and a change in the degree of opening of the valve acquired at a predefined time interval And a second step of estimating a time until a non-allowable control state is reached.

According to the present invention, it is possible to predict when the maintenance of the flow rate control device and its associated equipment becomes necessary (time until the controllable state is reached). As a result, on the operator side, it becomes easy to operate and manage the semiconductor manufacturing apparatus and the like equipped with the flow rate control device.

1 is a diagram showing an example of a relationship between an opening of a valve provided in a mass flow controller and a flow rate of a fluid.
Fig. 2 is a view showing a change with time of the valve opening degree for maintaining the target flow rate. Fig.
3 is a view showing another example of the relationship between the opening of the valve provided in the mass flow controller and the flow rate of the fluid.
4 is a block diagram showing a configuration of a flow rate control apparatus according to an embodiment of the present invention.
5 is a flow chart for explaining the flow rate control operation of the flow rate control apparatus according to the embodiment of the present invention.
6 is a flowchart for explaining a maintenance timing predicting operation of the flow control device according to the embodiment of the present invention.
7 is a cross-sectional view of the mass flow controller.

[Principle of the invention]

The use of the mass flow controller is in many cases to stably maintain the flow rate of the fluid at the target flow rate determined in advance. Therefore, assuming such a use, the influence of the clogging of the filter can be estimated to be a highly reliable detection condition. More specifically, a state in which the target flow rate is stably maintained at a predetermined target flow rate (the maximum target flow rate when there are a plurality of types of target flow rates) is detected at substantially constant intervals (for example, at intervals of 24 hours) The valve opening degree indicating signal of the valve opening degree sensor is acquired.

When it is considered that the clogging of the filter installed on the upstream side of the mass flow controller proceeds, it is the time when the valve opening degree becomes saturated to the upper limit (for example, 100%), , It is effective to make a judgment to perform the maintenance by predicting the time when this state becomes inaccessible control.

Therefore, the inventor of the present invention has obtained the information of the valve opening degree with high reliability based on the usage conditions peculiar to the mass flow controller, and when the valve opening degree is assumed to continue to change with time, %) Is considered to be a time when maintenance is required.

[Example]

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Patent Document 2 shows that when the opening degree of the valve provided in the mass flow controller is changed linearly with time, the flow volume of the fluid flowing through the flow path becomes smaller toward the hinge opening side. As described above, it is known that the valve opening degree MV and the flow amount PV have a nonlinear relationship, and the amount of change in the flow rate PV decreases with respect to the variation amount of the opening degree MV as the side closer to the hinge plane. An overview of the characteristics of such a mass flow controller is shown in Fig. On the other hand, in the example of Fig. 1, the flow rate (PV) is normalized to a value of 0 to 100%. Since the characteristic shown in Fig. 1 is a nonlinear convergence phenomenon, it can be expressed by an exponential function of the following equation.

PV = K {1.0-exp (-MV / A)} ... (One)

The function approximating the relationship between the valve opening degree MV and the flow rate PV is defined as a function of the constant term 1.0 and the term relating to the valve opening degree MV and the gain K, Lt; / RTI > A in Equation (1) is a coefficient giving a nonlinear convergence state. Curve cur1 in Fig. 1 shows the initial characteristics of the mass flow controller. It is assumed that the flow rate (PV) becomes the maximum value 100% at the valve opening degree (MV) = 100% and the curve cur1 is set to the coefficient value Can be expressed as an exponential function of.

PV = 104.0 {1.0-exp (-MV / 30.0)} ... (2)

K = 104.0 and A = 30.0 in equation (2) are examples of these values. In the case of the clogging of the filter installed in the flow path, it can be assumed that the nonlinearity, which is the characteristic of the valve itself of the mass flow controller downstream of the filter, does not change, so that the coefficient A can be regarded as being constant. Therefore, it is assumed that only the gain K decreases due to clogging of the filter or the like.

In predicting the maintenance time of the mass flow controller or the related equipment of the mass flow controller, it is presumed that several factors affect the operation time of the mass flow controller. However, whether the change in the gain K is accelerated or decelerated Since it is not deterministic, it is reasonable to assume that the gain K decreases at a constant pace in proportion to the running time of the mass flow controller.

Here, it is assumed that the predetermined target flow rate PVx is PVx = 60.0%. In other words, SPx = 60.0% is the most standard value given as the flow set value SP of the mass flow controller. When the valve opening degree in the initial state of the mass flow controller for correcting (setting) the fluid flow rate to PVx = 60.0% is MV1, MV1 = 25.8% by curve cur1. Since the nonlinear characteristic coefficient A = 30.0 has been obtained in advance, the gain K1 in the initial state can be inversely calculated based on PVx = 60.0% and MV1 = 25.8%.

K1 = PVx / {1.0-exp (-MV1 / A)}

  = 60.0 / {1.0-exp (-25.8 / 30.0)} = 104.0 ... (3)

Next, it is assumed that the valve opening degree MV for maintaining the target flow rate PVx = 60.0% is acquired at a constant interval (e.g., DELTA T = 24 hours interval) while the mass flow controller is continuously operated. It is assumed that a significant difference from the initial state is obtained when 72 hours of three times (n = 3) have elapsed. Specifically, it is assumed that the valve opening degree (MV) increased to MV2 = 29.4% at 72 hours from the start of operation.

The increase in the valve opening degree MV causes a decrease in the pressure at the point that flows into the mass flow controller due to the clogging of the filter and the valve opening degree MV for maintaining the target flow amount PVx = 60.0% It is the same phenomenon that it must be made larger than the initial state. The gain K2 at 72 hours from the start of operation can be inversely calculated according to the following equation based on PVx = 60.0% and MV2 = 29.4%.

K2 = PVx / {1.0-exp (-MV2 / A)}

 = 60.0 / {1.0-exp (-29.4 / 30.0)} = 96.0 (4)

Therefore, it is estimated that the gain K decreased by 8.0 from 72 hours in the initial state to K2 = 96.0 from K1 = 104.0 in the initial state. In this case, the characteristics of the mass flow controller are as shown by the curve cur2 in Fig.

It is assumed that the gain K decreases at a constant pace in proportion to the operation time of the mass flow controller. Therefore, when 72 hours elapse from the state of cur2, the gain K further decreases by 8.0, It can be assumed that the characteristic is like the curve cur3 (K3 = 88.0) in Fig. The valve opening degree MV3 at this point can be inversely calculated as shown in the following equation.

MV3 = -Aln {1.0- (PVx / K3)}

  = -30.0 ln {1.0- (60.0 / 88.0)} = 34.4 (5)

The above is summarized as follows. In the initial state (cur1), MV1 = 25.8%, MV2 = 29.4% in the state (cur2) after 72 hours from the start of operation, and MV3 = 34.4% in the state (cur3) after 72 hours Can be estimated. That is, the valve opening degree MV does not change at a constant face but the opening degree is accelerated by the influence of exponential nonlinearity. This is also the reason why it is not possible to simply assume that the change in the valve opening degree is a constant face.

The problem is that after several hours from when the valve opening degree MV for maintaining the target flow rate PV = 60.0% reaches MV = 100.0% to become the disabling control state (curve cur4 in FIG. 1) will be. If the gain K in the case of becoming in the impossible control state is Kh, the gain Kh can be calculated by the following equation.

Kh = PVx / {1.0-exp (-MV / A)}

  = 60.0 / {1.0-exp (-100.0 / 30.0)} = 62.2 ... (6)

Since the gain K changes by 8.0 every 72 hours (n DELTA T = 3 x 24), the time (K1) from the gain K2 = 96.0 of the state cur2 after 72 hours from the start of operation to the time when Kh reaches 62.2 ) Can be calculated by the following equation.

Th = n? T (Kh-K2) / (K2-K1)

  = 3 x 24.0 (62.2 - 96.0) / (96.0 - 104.0) = 304.0 ... (7)

That is, after 304 hours from the state of the curve cur2 in Fig. 1, Kh = 62.2 is reached. On the other hand, if the gain K3 of the state (cur3) after 144 hours from the start of operation is obtained as the performance, the time Th can be calculated by the following equation.

Th = n? T (Kh-K3) / (K3-K2)

  = 3 x 24.0 (62.2-88.0) / (88.0-96.0) = 232.0 ... (8)

In this manner, the time Th to reach MV = 100.0% can be estimated based on the current and recent valve opening degrees.

According to the calculations of the equations (1) to (8), the valve opening for maintaining the target flow rate PVx = 60.0% changes as time elapses as shown in Fig.

From the above, the order of prediction of the maintenance timing of the mass flow controller and its associated equipment can be summarized as follows (I) to (IV). On the other hand, in the following steps, the time point at which the gain K1 is calculated does not always mean the time point of the initial state, but means the time point of an arbitrary past state. Therefore, the effect of accelerating or decelerating the change of the gain K due to clogging of the filter or the like is ended only by the error with the recent pace.

(I) The valve opening degree MV1 for maintaining the target flow rate PVx was obtained before the time nΔT. Based on this, the gain K1 before the nΔT time is calculated (n is an integer of 1 or more). However, the nonlinearity coefficient A is prescribed in advance.

K1 = PVx / {1.0-exp (-MV1 / A)} ... (9)

(II) At this time, the valve opening degree MV2 for holding the target flow rate PVx was obtained. Based on this, the current gain K2 is calculated. However, it is assumed that the nonlinearity coefficient A does not change.

K2 = PVx / {1.0-exp (-MV2 / A)} ... (10)

(III) The gain Kh when the valve opening degree MV for maintaining the target flow rate PVx is 100% is calculated.

Kh = PVx / {1.0-exp (-100.0 / A)} ... (11)

(IV) Finally, the time Th until the gain K reaches Kh is calculated.

Th = n? T (Kh-K2) / (K2-K1) (12)

On the other hand, if the nonlinearity of Fig. 1 can be approximated, the same method can be applied in addition to the exponential function. For example, if the following function is a fractional function, the valve opening and the nonlinearity of the flow rate can be described only by arithmetic operation.

PV = K [{- A / (MV + B)} + C]

  = 1.0 [{- 3130.0 / (MV + 25.0)} + 125.2] ... (13)

K1 = PVx / [{- A / (MV1 + B)} + C] ... (14)

K2 = PVx / [{- A / (MV2 + B)} + C] ... (15)

Kh = PVx / [{- A / (100.0 + B)} + C] ... (16)

Like the equation (1), the function of the equation (13) is defined by the terms relating to the constant term (C = 125.2) and the valve opening degree (MV) and the gain (K) multiplied by these terms. According to the expressions (13) to (16), the characteristics of the mass flow controller can be represented by the same Fig. 3 as in Fig. The gain K1 in the state of the curve cur1 in FIG. 3 is 1.0, the gain K2 in the state of the curve cur2 is 0.923, the gain K3 in the state of the curve cur3 is 0.846, the valve opening degree MV ) Is 100%, the gain (Kh) of (cur4) is 0.596. That is, as in the example of Fig. 1, the gain K decreases at a constant pace in proportion to the operating time.

Next, the configuration of the flow control device (mass flow controller) of the present embodiment will be described. As shown in Fig. 4, the flow control device of the present embodiment is provided with a flow rate measuring section 1 for measuring the flow rate of the fluid flowing through the flow channel, a flow rate measuring device 1 for measuring the flow rate, A valve opening degree obtaining section 3 for obtaining a valve opening degree MV when the flow rate of the fluid is maintained at a predetermined target flow rate PVx during the flow rate control, An unrecyclable control time estimating section 4 for estimating a time Th until the flow rate of the fluid reaches the disengagement control state in which the flow rate can not be maintained at the target flow rate PVx, And an estimation result outputting section 5 for outputting information on the estimation result output section 5.

Next, the operation of the flow rate control apparatus of this embodiment will be described with reference to Figs. 5 and 6. Fig. 5 is a flow chart for explaining a flow control operation, and Fig. 6 is a flowchart for explaining a maintenance timing predicting operation.

The flow rate measuring section 1 continuously measures the flow rate of the fluid flowing through the flow path (flow path 105 in Fig. 7) (step S100 in Fig. 5). This flowmeter 1 corresponds to the fluid sensor 103 in Fig. 7 and has a well-known structure provided in the mass flow controller.

The flow rate control section 2 continuously operates the valve (the valve 104 in Fig. 7) so that the flow rate of the fluid measured by the flow rate measuring section 1 matches the target flow rate PVx set by the operator, for example Step S101). This flow control unit 2 also has a well-known configuration provided in the mass flow controller.

In this way, for example, the processes of steps S100 and S101 are repeatedly executed at prescribed intervals (for example, 50 msec.) Until the end of operation of the apparatus is instructed by the operator (YES in step S102 of FIG. 5).

On the other hand, the valve opening degree acquiring section 3 acquires the valve opening degree MV (target holding valve opening degree) when the flow rate of the fluid is maintained at the target flow rate PVx (step S200 in FIG. 6) . Specifically, the valve opening degree acquisition section 3 acquires the valve opening degree acquisition section 3 in such a manner that the absolute value of the deviation between the flow rate measured by the flow rate measurement section 1 and the target flow rate PVx continues to fall within the specified value , It is determined that the flow rate of the fluid is maintained at the target flow rate (PVx), and the current valve opening degree (MV) is acquired. The value of the constant time t (t <? T) is set in the valve opening degree acquisition section 3 as a prescribed value.

On the other hand, although the valve opening degree itself may be detected, the actual valve opening degree is not detected, and a signal (for example, valve opening degree indicating signal or valve driving current) output to the valve from the flow rate control section 2 is acquired , The valve opening degree may be determined based on this signal.

Next, the incapacity control time estimating unit 4 determines whether or not the valve opening degree MV reaches the upper limit (for example, 100%) based on the change in the valve opening degree MV acquired at the predefined time interval, And estimates the time Th from when the flow rate of the fluid reaches the disengagement control state where it can not be maintained at the target flow rate PVx. 4, the incoherent control time estimating section 4 includes a first gain calculating section 40 for calculating the gain K1, a second gain calculating section 41 for calculating the gain K2, A third gain calculating section 42 for calculating the gain Kh and a time calculating section 43 for calculating the time Th.

The first gain calculating unit 40 of the incapable control time estimating unit 4 calculates the gain K1 before the current point of time at which the time Th is to be estimated by using the equation (9) (Step S201 ). As described above, MV1 in the equation (9) is the valve opening degree (MV) acquired by the valve opening degree acquisition section 3 before the nΔT time. The coefficient A in the equation (9) is set in the ineffective control time estimating section 4 as a prescribed value. In order to grasp the coefficient A, for example, a flow rate test of the flow rate control device may be performed in advance to check the value of the coefficient A. [

Subsequently, the second gain calculating unit 41 of the incapable control time estimating unit 4 calculates the current gain K2 at which the time Th is to be estimated, using equation (10) (step S202 ). As described above, MV2 in the equation (10) is the latest valve opening degree (MV) acquired by the valve opening degree acquisition section 3 at the present time.

The third gain calculating unit 42 of the incapacity control time estimating unit 4 calculates the gain at the time when the valve opening degree MV reaches the upper limit at a time point ahead of the current point on the basis of the target flow amount PVx (Kh) is calculated by the equation (11) (step S203 in Fig. 6).

The time calculation unit 43 of the incapacity control time estimating unit 4 calculates the time Th from the present point of time to the disabling control state based on the gains K1, K2 and Kh and the time nΔT as (12) (step S204 in FIG. 6). Thus, the processing of the incapable control time estimating unit 4 is terminated.

The estimation result output unit 5 outputs the estimation result of the incapable control time estimation unit 4 (Fig. 6, step S205). Examples of the output method of the estimation result include numerical display of the time Th, alarm output based on the time Th, transmission of the information of the estimation result to the outside, and the like. In the case of the alarm output, when the time Th becomes less than the predetermined threshold time (for example, less than 48 hours), the LED for notifying the alarm may be turned on.

The valve opening degree acquiring section 3, the incoherent control time estimating section 4 and the estimation result output section 5 wait until the operation end of the apparatus is instructed by the operator (YES in Fig. 6, step S206) The processes of steps S200 to S205 are repeatedly executed every predetermined period DELTA T (for example, 24 hours).

As described above, in the present embodiment, it is possible to predict when the maintenance of the flow control device and its associated equipment (filter installed in the flow path, etc.) (maintenance time Th until the control state becomes inaccessible) is required. The operator can predict when the maintenance such as calibration should be required based on the estimation result of the flow rate control apparatus, so that the operator can easily manage the semiconductor manufacturing apparatus and the like.

On the other hand, the unreliable control time estimating section 4 calculates the gain K1 of nΔT time (n is an integer of 1 or more) before the valve opening degree acquiring section 3 calculates the valve opening degree MV every cycle ΔT, , The integer n can take various values. The valve opening degree MV can not be acquired at the time point when the valve opening degree acquisition section 3 determines that the flow rate of the fluid is not maintained at the target flow rate PVx, The data of &quot; Further, in order to appropriately estimate the time Th until the non-control state, it is preferable that the time n DELTA T is an appropriate range that is not too long and not too short.

Therefore, the incapacity control time estimating unit 4 determines whether or not the valve opening degree acquiring unit 3 can acquire the valve opening degree MV from among past time points that are nΔT times longer than the current time point at which the time Th is to be estimated (9) and (12) for n &lt; [Lambda] &gt; T.

The unreceivable control time estimating unit 4 also calculates the gains K1 and K2 by using the equations (14), (15) and (16) instead of the equations (9) K2, and Kh may be calculated. The coefficients A, B and C in the equations (14), (15) and (16) are set in the ineffective control time estimating unit 4 as prescribed values. In order to grasp the coefficients A, B, and C, for example, a flow rate test of the flow rate control device may be performed in advance.

Although the target flow rate PVx is assumed to be constant in this embodiment, the target flow rate PVx may be changed on the way. 6 is a process in which the target flow rate PVx is assumed to be maintained at a constant value. Therefore, when the target flow rate PVx is changed on the way, the process of FIG. 6 may be executed for each target flow rate PVx. For example, when the target flow rate PVx is changed from 60.0% to PVx = 50.0%, the data of the valve opening degree MV obtained when PVx = 60.0% is not used and the valve opening degree after PVx = 50.0% 6 using the data of the motion vector MV.

In the present embodiment, all of the structures shown in Fig. 4 are provided in the flow rate control device (mass flow controller), but the present invention is not limited to this. The valve opening degree acquiring section 3, the disregarded control time estimating section 4 and the estimation result output section 5 are installed in a host device (for example, a programmable logic controller (PLC)) as a maintenance time predicting device, 1 and the flow rate control section 2 may be used in combination with a general micro flow controller.

The flow rate control device described in this embodiment can be realized by a computer having a CPU (Central Processing Unit), a storage device, and an interface, and a program for controlling these hardware resources. Likewise, the maintenance time predicting device including the valve opening degree acquisition section 3, the incapable control time estimation section 4, and the estimation result output section 5 can be realized by a computer and a program. The CPU of each apparatus executes the processing described in this embodiment in accordance with the program stored in each storage device. Thus, the maintenance timing predicting method of the present embodiment can be realized.

The present invention can be applied to a technique for predicting a time when maintenance of a flow control device and its related equipment is required.

1: Flow measuring part 2: Flow control part
3: valve opening degree acquisition section 4:
5: estimation result output unit 40 to 42: gain calculation unit
43: Time calculation unit

Claims (10)

A valve opening degree acquiring section configured to acquire an opening degree of the valve when the flow rate of the fluid is maintained at a predetermined target flow rate during flow rate control for controlling the flow rate of the fluid using a valve;
A control unit for controlling the flow rate of the fluid based on the approximate relation between the opening of the valve and the flow rate of the fluid and the change in the opening degree of the valve acquired at a predefined time interval, Lt; RTI ID = 0.0 &gt; time &lt; / RTI &gt;
And estimating the maintenance time. 2. The apparatus according to claim 1, wherein the inactivity-free time estimator estimates the time until the degree of opening of the valve, which is obtained by the valve-opening degree acquiring section, reaches an upper limit, Wherein the maintenance time prediction unit estimates the maintenance time. 3. The method according to claim 1 or 2, wherein the function is defined by at least a term relating to the degree of opening of the valve and a gain which is a numerical value multiplied by this term,
Based on the equation obtained from the function and the change in the degree of opening of the valve acquired by the valve opening degree acquisition section when it is assumed that the gain decreases with passage of time, And estimates the time until the control state is reached. 4. The maintenance time predicting apparatus according to claim 3, wherein the function is a function approximating a nonlinear relationship between the opening of the valve and the flow rate of the fluid, and the term relating to the degree of opening of the valve is expressed by an exponential function. 4. The maintenance time predicting apparatus according to claim 3, wherein the function is a function approximating a nonlinear relationship between the opening of the valve and the flow rate of the fluid, and the term relating to the degree of opening of the valve is expressed by a fraction function. The apparatus as claimed in claim 3,
Calculating the gain at the time point of the past based on the degree of opening of the valve acquired by the valve opening degree acquiring section at a point in time past the current point of time for estimating the time until the control point becomes the disabling control state, A gain calculator,
A second gain calculating section for calculating the present gain at the present time based on the degree of opening of the valve acquired by the valve opening degree acquiring section at present;
A third gain calculating section for calculating the gain when the opening degree of the valve acquired by the valve opening degree acquiring section reaches the upper limit at a point in time before the current point based on the target flow rate;
A gain calculator for calculating a gain of the gain control unit based on a gain calculated by the first, second and third gain calculators and a time from the past time point to a current time point,
Wherein the maintenance time predicting unit is configured to predict the maintenance time. 3. The maintenance time predicting apparatus according to claim 1 or 2, further comprising an estimation result outputting section for numerically displaying the time estimated by the incoherent control time estimating section. 3. The apparatus according to claim 1 or 2, further comprising an estimation result output section for generating an alarm when the time estimated by the incapable control time estimating section becomes less than a predetermined threshold time Device. A flow rate measuring section for measuring a flow rate of the fluid flowing through the flow path,
A valve provided in the flow path,
A flow rate control unit operable to operate the valve so that the flow rate measured by the flow rate measurement unit matches a predetermined target flow rate,
The maintenance time predicting apparatus according to claim 1 or 2,
And,
Wherein the valve opening degree acquiring section of the maintenance time predicting device acquires an opening degree of the valve installed in the flow path. A first step of acquiring an opening degree of the valve when the flow rate of the fluid is maintained at a predetermined target flow rate during flow rate control for controlling the flow rate of the fluid using a valve;
A control unit for controlling the flow rate of the fluid based on the approximate relation between the opening of the valve and the flow rate of the fluid and the change in the opening degree of the valve acquired at a predefined time interval, The second step of estimating the time until
And estimating a maintenance time of the vehicle.

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