JP2000039347A - Flowrate inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flowrate inspection device capable of performing correct inspection even with a fluctuation of fluid pressure given to a body to be inspected. SOLUTION: With this flowrate inspection device, pressure accumulated in fluid pressure source 11 is taken out through a pressure control valve 12 at specific pressure and the fluid pressure is given to the body to be inspected by way of a flowmeter 14 and whether or not a specified flowrate is obtained is inspected by measuring the flowrate of the fluid flowing the body to be inspected. In this case, a pressure sensor 2 measuring the fluid pressure given to the body to be inspected is provided, a reference fluid pressure P1 detected with this pressure sensor is stored. If fluid pressure P2 deviating from the reference fluid pressure P1 is given by the body to be inspected through the measurement, the flowrate value Q2 measured at the moment is corrected by operation Q1=Q2√P1/P2 and corrected to the flowrate value Q1 under the reference fluid pressure P1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate inspection apparatus used for inspecting an instrument used for flowing a fluid at a predetermined flow rate, such as a gas appliance or a water supply appliance.

[0002]

2. Description of the Related Art FIG. 4 shows a schematic configuration of a conventional flow rate inspection apparatus. In the figure, reference numeral 11 denotes a fluid pressure source such as a compressor. The fluid pressure (for example, air pressure) taken out of the fluid pressure source 11 is regulated to a predetermined pressure by a pressure regulating valve 12 and supplied to a flow meter 14. The flow meter 14 shows a case where an orifice type flow meter constituted by a throttle 14A and a differential pressure gauge 14B for measuring a pressure difference between an input side and an output side of the throttle 14A is used. The use of the meter does not relate to the essence of the invention.

An on-off valve 15 is connected to the output side of the flow meter 14, a work connection port 16 is connected to the output side of the on-off valve 15, and a test object 18 is connected to the work connection port 16. An electric output terminal of the differential pressure gauge 14B constituting the flow meter 14 has a display function of displaying a flow value, and a display / judgment means for judging whether the flow value is within a predetermined allowable range and judging pass / fail. 17 is connected.

In the inspection mode, when the test object 18 is connected to the work connection port 16, the on-off valve 15 is controlled to open, and the fluid pressure stored in the fluid pressure source 11 is measured by the flow meter 14.
To the object 18 to be inspected. At this time, the flow rate of the fluid flowing through the flow meter 14 matches the flow rate of the test object 18. Thus, the flow rate of the test object 18 is inspected.

[0005]

In the conventional flow rate inspection apparatus, fluid pressure is extracted from a fluid pressure source 11 through a pressure regulating valve 12, and an inspection is performed with a pressure gauge 13 set to a constant pressure value. However, when the on-off valve 15 is opened and the fluid is actually passed through the test object 18, there is no guarantee that the fluid pressure at the work connection port 16 is the pressure value indicated by the pressure gauge 13. In some cases, the pressure value deviates from the pressure value indicated in step S13. As a result, an error may occur in the determination result of the display / determination unit 17.

That is, the range of the flow rate allowed for the test object 18 can be displayed in a hatched area shown in FIG. Assuming that the display / judgment means 17 sets a comparison value so as to judge the result of inspection at the set reference pressure P ₀ as the normal good judgment area Q _0-1 , the pressure at the work connection port 16 is shown in FIG. When the pressure is shifted to P ₁ or P ₂ , the good judgment area when the pressure is P ₁ is _Q1-1 ,
Good determination area when the pressure is shifted to P ₂ is shifted to Q _2-1. Therefore, even if the pressure changes to P ₁ and P _2, when the judgment operation is performed without correcting the good judgment area to Q _1-1 and Q _2-1 , the general inspection object is judged to be defective. Will be lost.

[0007] However, it is difficult to actually correct the comparison value for quality determination in conjunction with the pressure changes P ₁ and P ₂ . Also, the pressure regulating valve 12 is used to prevent pressure fluctuation.
It is also difficult to control automatically. Therefore, conventionally, to minimize the pressure fluctuation at the work connection port 16,
For example, the pressure fluctuation at the work connection port 16 is suppressed by a method such as reducing the amount of differential pressure generated in the flow meter 14, but it is difficult to completely suppress the pressure fluctuation.

An object of the present invention is to propose a flow rate inspection apparatus capable of obtaining a correct inspection result even if a pressure fluctuation occurs at a work connection port.

[0009]

According to a first aspect of the present invention, there is provided a flow rate inspection apparatus which adjusts a fluid pressure accumulated in a fluid pressure source to a desired pressure through a pressure regulating valve and takes out the fluid. Pressure is applied to the test object having the orifice characteristic through the flow meter, and the atmospheric pressure P is applied through the test object.
_In a flow rate inspection device that determines the quality of an object to be inspected based on whether or not a flow rate discharged to ₀ falls within a predetermined flow rate range, a pressure sensor that measures a fluid pressure applied to the object to be inspected, storage means for storing a standard value P ₁ of the fluid pressure imparting, in the test mode, if the pressure P ₂ the pressure by the pressure sensor to measure deviates from the standard value P _1, the flow rate Q ₁ that flows at the pressure P ₂ , Q ′ ₀ = Q ₁ √P ₁ / P ₂
Corrected by the flow rate Q 'in the standard value P ₁ of the fluid pressure
_{The present} invention proposes a flow rate inspection apparatus provided with a correction operation unit for correcting the flow rate to _zero .

The flow rate inspection apparatus proposed in claim 2 of the present invention proposes a flow rate inspection apparatus used when the flow rate characteristic of the inspection object has a laminar flow characteristic. The operation expression is Q ' ₀ = Q ₁ · P ₁ / P ₂ . The flow rate inspection apparatus proposed in claim 3 of the present invention proposes a flow rate inspection apparatus capable of accurately measuring the flow rate of an object having an arbitrary flow characteristic without questioning the flow characteristic of the object. Things.

In the flow rate inspection apparatus proposed in claim 3,
Calibration mode is provided.
Fluid pressure P having a predetermined reference value for the specimen₀And that
The flow rate Q of the flowing fluid₀Is measured. Fluid at this time
Pressure P₀And flow rate Q₀Is stored. Next, the reference value P₀Less
Low fluid pressure P₁And the flow rate Q of the fluid flowing at this time
₁Is measured. This fluid pressure P₁And flow rate Q₁Is stored.

Next, a pressure P ₂ slightly higher than the reference value P ₀ is applied to the test object, the flow rate Q ₂ at this time is measured, and these are stored. Each of these stored values P ₀ , Q ₀ , P ₁ , Q ₁ ,
The _{P 2, Q 2, Q 0} = Q 1 in _{(A√P 0 / P 1 + B} · P 0 / P 1) Q 0 = Q 2 (A√P 0 / P 2 + B · P 0 / P 2) The calibration coefficients A and B are obtained from equation (2), and an equivalent flow rate value measured at the correct reference value P ₀ is obtained from the determined correction operation equation even when a pressure deviating from the reference value P ₀ is given. It was done.

Therefore, according to the present invention, even if the fluid pressure applied to the test object deviates from a predetermined reference value, the deviated pressure value is measured. A flow value equivalent to a state in which a fluid pressure having a value is given can be obtained. Therefore, there is an advantage that the correct quality can always be determined without changing the comparison value for the quality determination.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the first and second embodiments of the present invention.
1 shows an embodiment of the flow rate inspection device proposed in the above. That is, an embodiment in which the flow rate characteristics of the test object 18 are an orifice type and a laminar flow type will be described. In FIG. 1, parts corresponding to those in the figure are denoted by the same reference numerals. In the present invention, the work connection port 16
The pressure sensor 21 is connected in the vicinity of
Near the work connection port 16, that is, the test object 18
The pressure value measured by the pressure sensor 21 is a differential pressure (gauge pressure) from the atmospheric pressure by measuring the pressure applied to the test object 18 and exhausting the test object 18 to the atmosphere.

Further, in the calibration mode, the pressure sensor 2
A standard value P ₁ measured at 1, provided with storage means M ₁ for storing the reference pressure P _1. In the embodiment shown in FIG. 1 shows a case where the storage means M ₁ provided inside the correction calculation unit 22 to be described later. The flow rate inspection is performed as follows. Each time the test object 18 is replaced, the pressure sensor 21 measures the pressure at the work connection port 16 and the flow rate from the flow meter 14.
Especially when the value of the pressure in the measured value is out of the reference pressure value P ₁ is the measured value P ₂ and Q ₂ Q ₁ = Q ₂ √P
_The flow rate is corrected to a flow value equivalent to the case where the standard pressure value P ₁ is given by ₁ / P ₂ , and the corrected flow value is input to the display / judgment means 17 to display the correct flow rate and execute the pass / fail judgment. I do.

Formula used for correction calculation Q ₁ = Q ₂ √P ₁ /
P ₂ is determined as follows. When the flow rate characteristic of the test object 18 is an orifice type, between the flow rate Q and the differential pressure value ΔP applied to the test object 18, Q = K ₁ √ΔP / δ (1) K: There is a relation of constant, δ: density of fluid.

The expression (1) means that the test object 1
The volume flow rate flowing into the sample 8 is K ₁ : a proportionality constant determined by the shape and the like of the test object 18, and proportional to the square root of the differential pressure ΔP between the inlet and the outlet of the test object 18 and inversely proportional to the square root of the density δ. It is. Q ₁ = K ₁ √ΔP ₁ / δ (2) P ₀ : Atmospheric pressure P ₁ : Reference pressure value In equation (1), ΔP = P ₁ −P ₀ = ΔP ₁ ΔP ₂ = P ₂ −P _{When 0,} the flow rate represented by the equation (1) is: Q ₂ = K ₁ √ΔP ₂ / δ (3) The flow rate of the measured pressure value P ₁ is to be obtained.
(3) When the flow rate Q ₂ was measured in the pressure values [Delta] P ₂ of the formula, corrected to obtain the correct flow rate Q ₁ is _{Q 1 = Q 2 √ΔP 1 /} ΔP 2 ............ (4) where P _When expressed as ₀ = 0, that is, expressed as a gauge pressure, the equation (4) is as follows: Q ₁ = Q ₂ √P ₁ / P ₂ (5) Eventually, the pressure P ₂ measured by the pressure sensor 21 and the flow rate measured at this time and pressure corrected Q ₂ in the correction calculation equation (5) obtains the correct flow rate Q _1. If the flow rate determined for this flow rate Q ₁ becomes the flow rate comparison with the same pressure value. That there in comparison proportionality coefficient K ₁ becomes effective cross comparing the area of the hole diameter of the device under test 18.

When the test object 18 has laminar flow characteristics, Q =
K / η · ΔP and ΔP are differential pressures at both ends of the work, and K ₁ is a coefficient determined by the shape of the test object 18. η is the viscosity coefficient of gas, and the flow rate is proportional to the differential pressure ΔP when the test object 18 has laminar flow characteristics. This is because a laminar flow characteristic is obtained when measuring the flow rate flowing through a thin pipe. Q = (K ₁ / η) · ΔP (6) Similarly, Q ₁ = Q ₂ · (P ₁ / P ₂ ) (7)

Therefore, when the flow rate characteristic of the test object 18 is of the orifice type, the calculation formula calculated by the correction calculation means 22 is Q ₁ = Q ₂ √P ₁ / P ₂ , and the flow rate characteristic of the test object 18 is In the case of laminar flow, the correction equation is Q ₁ = Q ₂ · P ₁ / P ₂ .

In the above, the embodiment in the case where the flow characteristic of the test object 18 is clearly known as the orifice characteristic or the laminar flow characteristic has been described. In the flow rate inspection apparatus proposed in claim 3 of the present invention, by providing the calibration mode, it is possible to correct even when the inspection object 18 has both the orifice and laminar flow characteristics. FIG. 2 shows the embodiment. First, in the calibration mode, the standard reference pressure P of the test object 18 is set.
Measure the flow rate at _zero . It is assumed that the flow rate at this time is Q ₀ . The pressure P ₀ and the flow rate value Q ₀ are stored in the storage means M ₁
And it is stored in the M _4. Then lowered a little pressure from the reference pressure P ₀ is set to P ₁ (see FIG. 3), the flow rate at this time is Q ₁
The pressure and flow rate values are stored in storage means M ₂ and M ₅
To memorize.

Next, the pressure is slightly increased from the reference pressure P ₀ to P ₂
If the flow rate at this time is Q ₂ , the pressure P ₂
And stores the flow rate Q ₂ in the storage means M ₃ and M _6. The following equations (8) and (9) hold from these measured values. Q ₀ = Q ₁ (A√P ₀ / P ₁ + B ・ P ₀ / P ₁ ) (8) Q ₀ = Q ₂ (A√P ₀ / P ₂ + B ・ P ₀ / P ₂ ) (9) Here, for A and B, calibration coefficients A and B can be obtained from calibration coefficients (8) and (9). From the correction calculation formulas determined by the obtained calibration coefficients A and B, the correction calculation means 22 can correct the flow value of an arbitrary test object 18 to obtain a corrected flow value.

The flow rate value Q corrected by the correction calculation means 22 is sent to the display / judgment means 17 and compared with a comparison value prepared in the display / judgment means 17. This comparison value is defined as an allowable range Q _{0-1 at} the reference pressure P ₀ shown in FIG. 5. If each corrected flow rate value Q falls within the allowable range Q _0-1 , it is determined to be good. Is done. The above-described operation correcting means 22 includes storage means M _{1 to} M ₈ and executes the operation, so that the correcting operation means 22 can be constituted by a microcomputer.

[0023]

As described above, according to the present invention, the pressure value P _{0 based on the} pressure applied to the test object 18 is used as a reference.
, The flow rate error caused by the pressure fluctuation can be corrected. Therefore, the display / judgment means 17
In this case, only the standard comparison area Q _0-1 (see FIG. 5) needs to be prepared as the comparison value for judging pass / fail, so that the configuration can be simplified. Further, since it is not necessary to adjust the pressure regulating valve 12 so that the pressure applied to the work connection port 16 always becomes the reference value P ₀ , the advantage that the configuration of the flow rate inspection device can be simplified also in this point is obtained. . Further, the flow rate inspection device proposed in claim 3 has an advantage of high versatility because the flow rate characteristic of the test object 18 is not selected.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining an embodiment of a flow rate inspection device proposed in claims 1 and 2 according to the present invention.

FIG. 2 is a block diagram for explaining an embodiment of a flow rate inspection device proposed in claim 3 of the present invention.

FIG. 3 is a graph for explaining the operation of FIG. 2;

FIG. 4 is a block diagram for explaining a conventional technique.

FIG. 5 is a graph for explaining inconvenience of the conventional flow rate inspection device shown in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Fluid pressure source 12 Pressure regulator 13 Pressure gauge 14 Flowmeter 15 On-off valve 16 Work connection port 17 Display / judgment means 18 Inspection object

Claims (3)

[Claims] 1. A. First Embodiment Regulates the fluid pressure accumulated in the fluid pressure source
Adjust the pressure to the desired value through a valve and take it out.
Orifice characteristics
Is applied to the test object having the atmospheric pressure P through the test object.₀
Whether the flow discharged to the furnace is within the specified flow range
Flow rate inspection equipment that determines the quality of the inspection object
And B. A pressure cell for measuring the fluid pressure applied to the test object
And C. Reference value P of fluid pressure given to test object₁Note to remember
Storage means; In the test mode, the pressure measured by the pressure sensor
Force is the above standard value P₁Out of pressure P_TwoIn the case of
Pressure P_TwoFlow Q_TwoTo Q₁= Q_Two√P ₁/ P_Two
And the fluid pressure reference value P₁Flow rate at₁
And a correction calculation means for correcting the flow rate. 2. A. The fluid pressure accumulated in the fluid pressure source is adjusted to a desired pressure through a pressure regulating valve, taken out, and the regulated fluid pressure is applied to a test object having a laminar flow characteristic through a flow meter, thereby performing a test. B. A flow rate inspection device that determines the quality of an object to be inspected based on whether or not a flow rate released to the atmospheric pressure P ₀ through the body falls within a predetermined flow rate range. B. a pressure sensor for measuring a fluid pressure applied to the test object; Storage means for storing a reference value P ₁ of the fluid pressure to be supplied to the device under test, D. In test mode, when the pressure above the pressure sensor measures the pressure P ₂ which deviates from the reference value P _1, the flow rate Q ₂ to which flows in the pressure P _2, corrected by _{Q 1 = Q 2 P 1 /} P 2 The flow rate Q at the fluid pressure reference value P _1
1. A flow rate inspection apparatus, comprising: a correction operation means for correcting the value to ₁ ; 3. A. Regulates the fluid pressure accumulated in the fluid pressure source
Adjust the pressure to the desired value through a valve and take it out.
Inspection with unspecified flow characteristics through flow meter
Flow rate applied to the body and released to atmospheric pressure through the body under test
The test object depends on whether
B. In the flow rate inspection device for determining the quality of B. A pressure cell for measuring the fluid pressure applied to the test object
And C. Standard of fluid pressure given to test object in calibration mode
Value P₀And the flow rate Q₀And the reference value P₀Than
Low pressure value P₁Given the pressure value P₁And its
Flow rate Q₁And the reference value P₀Higher pressure value P_Two
Given the pressure value P₁And the flow rate at that time
Q_TwoStorage means for respectively storing D. Each pressure value P stored in this storage means₀, P₁, P_Two
And flow value Q₀, Q₁, Q_TwoThe flow for the pressure value P
Quantity Q_PCalculation formula including calibration coefficients A and B, Q ₀connection of
Equation Q₀= Q_P(A√P₀/ P + BP₀/ P) to Q₀= Q₁(A√P₀/ P₁+ BP₀/ P₁) And Q₀= Q_Two(A√P₀/ P_Two+ BP₀/ P_Two) To determine the calibration coefficients A and B, determine the correction equation,
Reference value P in measurement mode₀Inspection under the condition given
E. correction operation means for correcting the flow rate flowing to the body; The correction result calculated by the correction calculating means is used as a comparison value.
And a display / judgment means for comparing with a flow rate inspection device.