Flow detection device and method for correcting flow detection device

Abstract

To provide a flow detection device capable of improving flow detection accuracy of fluid, and a correction method of the flow detection device.SOLUTION: A flow detection device 1 includes a flow path 10 having a flow wall 11 that expands and contracts according to a pressure change of a fluid flowing inside, a pressure chamber forming portion 20 that forms a pressure chamber 20A covering at least a part of a periphery of the flow wall 11, a first pressure sensor 30 that measures a pressure change of the pressure chamber 20A due to a displacement of the flow wall 11, and a correction device 40 that removes at least a part of noise of an atmosphere pressure included in an output value of the first pressure sensor 30. The correction device 40 includes a second pressure sensor 41 which is disposed outside the pressure chamber 20A and measures the atmosphere pressure, and an arithmetic device 42 which corrects an output value of the first pressure sensor 30 based on the output value of the second pressure sensor 41 delayed by a fixed time.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a flow detection device and a method for correcting a flow detection device. [Background technology]

[0002] The following Patent Document 1 discloses a diagnostic device for a fuel transpiration prevention device, which is characterized by comprising an atmospheric pressure sensor that detects atmospheric pressure, and a protection means that stops the diagnostic process or invalidates the diagnostic results when there is a change in atmospheric pressure during diagnosis that exceeds the limit at which the diagnostic accuracy of the diagnostic device can be maintained. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3444000 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when trying to measure pressure changes of a fluid flowing inside a tube or the like at the level of, for example, several hundred Pa, changes in atmospheric pressure may become noise, making it difficult to detect the flow.

[0005] The present invention has been made in view of the above problems, and has as its object to provide a flow detection device and a correction method for a flow detection device that can improve the accuracy of detecting the flow of a fluid. [Means for solving the problem]

[0006] As a result of extensive research, the inventors of the present invention have discovered that the effect of atmospheric pressure occurs with a certain time delay on a fluid flowing inside a tube or the like, and have come up with the invention described below.

[0007] (1): A flow detection device according to one aspect of the present invention comprises a flow path having a flow wall that expands and contracts due to pressure changes in a fluid flowing therethrough, a pressure chamber forming portion that forms a pressure chamber that covers at least a portion of the periphery of the flow wall, a first pressure sensor that measures changes in pressure in the pressure chamber due to displacement of the flow wall, and a correction device that removes at least a portion of atmospheric pressure noise contained in the output value of the first pressure sensor, wherein the correction device comprises a second pressure sensor that is arranged outside the pressure chamber and measures atmospheric pressure, and a calculation device that applies correction to the output value of the first pressure sensor based on the output value of the second pressure sensor delayed by a certain time.

[0008] According to the flow detection device of this embodiment, the first pressure sensor measures the change in pressure in the pressure chamber surrounding the flow wall of the flow path, and the second pressure sensor measures the change in atmospheric pressure. Based on the measurement result of the second pressure sensor, a correction is made to the first pressure sensor with a certain time delay, thereby improving the accuracy of fluid flow detection.

[0009] (2) In the flow detection device according to aspect (1), the calculation device may use a moving average of the output value of the second pressure sensor delayed by the predetermined time with respect to the output value of the first pressure sensor as the correction value.

[0010] In this case, by using the moving average of the output values ​​of the second pressure sensor as the correction value, the difference in the output values ​​of the second pressure sensor is stabilized, thereby reducing the atmospheric pressure noise contained in the output values ​​of the first pressure sensor and further improving the accuracy of fluid flow detection.

[0011] (3): In the flow detection device according to aspect (2), the moving average time may be set to 30 minutes to 300 minutes.

[0012] In this case, the difference in the output value of the second pressure sensor becomes more stable.

[0013] (4) In the flow detection device according to any one of (1) to (3), the flow channel may have an inner diameter D1 and an outer diameter D2 such that D2≧10×D1.

[0014] In this case, the flow of fluid can be detected with high accuracy in a flow channel with a thick flow wall, where the difference between the inner diameter and the outer diameter is 10 times or more.

[0015] (5): In the flow detection device according to any one of (1) to (4), the inner diameter of the flow channel may be 1 mm or less.

[0016] In this case, the flow of fluid can be detected with high accuracy in a small flow channel with an inner diameter of 1 mm or less.

[0017] (6) In the flow detection device according to any one of (1) to (5), the flow channel may be formed from an elastomer.

[0018] In this case, the flow of the fluid can be detected with high accuracy in the flow path formed from the elastomer.

[0019] (7) In the flow detection device according to any one of (1) to (5), the flow channel may be formed from polyvinyl chloride.

[0020] In this case, the flow of the fluid can be detected with high accuracy in the flow path formed from polyvinyl chloride.

[0021] (8): A correction method for a flow detection device according to one aspect of the present invention is a correction method for removing at least a portion of the atmospheric pressure noise contained in the output value of the first pressure sensor in a flow detection device that includes a flow path having a flow wall that expands and contracts due to pressure changes in the fluid flowing therethrough, a pressure chamber forming portion that forms a pressure chamber that covers at least a portion of the periphery of the flow wall, and a first pressure sensor that measures changes in pressure in the pressure chamber due to displacement of the flow wall.The correction method includes placing a second pressure sensor outside the pressure chamber to measure the atmospheric pressure, and correcting the output value of the first pressure sensor based on the output value of the second pressure sensor delayed by a certain time.

[0022] According to the correction method for the flow detection device of this embodiment, the change in pressure in the pressure chamber surrounding the flow wall of the flow path is measured by a first pressure sensor, and the change in atmospheric pressure is measured by a second pressure sensor, and based on the measurement result of the second pressure sensor, a correction is made to the first pressure sensor with a certain time delay, thereby improving the accuracy of fluid flow detection. [Effects of the Invention]

[0023] According to the above aspect of the present invention, it is possible to provide a flow detection device and a correction method for a flow detection device that can improve the accuracy of detecting the flow of a fluid. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a cross-sectional view of a flow detection device according to an embodiment; [Figure 2] FIG. 4 is a diagram showing changes in output values ​​of a first pressure sensor and a second pressure sensor when the inside of a flow channel according to an embodiment is filled with air. [Figure 3] FIG. 4 is a diagram showing changes in output values ​​of a first pressure sensor and a second pressure sensor when the inside of a flow channel according to an embodiment is filled with liquid. [Figure 4] 10 is a diagram showing changes in output values ​​of a first pressure sensor and a second pressure sensor and a moving average of the second pressure sensor when the inside of a flow channel according to an embodiment is filled with liquid. FIG. [Figure 5] 10 is a diagram showing the difference between the first pressure sensor and the second pressure sensor according to one embodiment, and the difference between the moving average of the first pressure sensor 30 and the second pressure sensor. FIG. [Figure 6] FIG. 10 illustrates a preferred moving average (time) for a second pressure sensor according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a flow detection device 1 according to an embodiment. As shown in FIG. 1, the flow detection device 1 includes a flow path 10, a pressure chamber forming portion 20, a first pressure sensor 30, a correction device 40, and an output device 50.

[0026] The flow channel 10 has a flow wall 11 that expands and contracts in response to pressure changes of the fluid flowing therethrough. The flow channel 10 of this embodiment is a so-called liquid delivery tube that has at least flexibility and elasticity, and is formed long with a constant inner diameter (cross-sectional area). Note that, depending on the type of fluid, application, etc., various treatments such as oxidation treatment may be performed on the flow wall 11 as necessary, and various properties such as heat resistance and transparency may be added.

[0027] The flow path 10 is connected to, for example, a pulsating pump (not shown). The pulsating pump can be a so-called roller pump that sucks in a fluid (liquid) stored in a water supply tank and discharges it while pulsating at a known reference frequency. Since the flow path 10 has at least flexibility and elasticity, the flow wall 11 expands and contracts (displaces) in a wavy manner in response to the pulsation of the fluid.

[0028] The flow channel 10 is formed from an elastomer, more specifically, polyvinyl chloride. The flow channel 10 has a flow wall 11 that is relatively thick compared to the internal space through which the fluid flows. Specifically, when the inner diameter of the flow channel 10 is D1 and the outer diameter is D2, the relationship D2 ≥ 10 × D1 holds. D1 is, for example, 1 mm or less. In this embodiment, for example, D1 is 0.25 mm and D2 is 3.5 mm. Note that the material forming the flow channel 10 and the thickness of the flow wall 11 are not limited to those described above.

[0029] In the following description, the direction in which the central axis O of the flow channel 10 extends is referred to as the axial direction, and the direction perpendicular to the axial direction is referred to as the radial direction. For convenience of explanation, in the following description, the flow channel 10 side may be referred to as the lower side, and the pressure chamber forming section 20 side may be referred to as the upper side. Note that the pressure chamber forming section 20 side does not have to be the upper side in the direction of gravity.

[0030] The pressure chamber forming portion 20 forms a pressure chamber 20A that covers at least a portion of the periphery of the flow wall 11. The pressure chamber forming portion 20 includes a sensor substrate 21 on which a first pressure sensor 30 and a second pressure sensor 41 (described later) are attached, and a contact member 22 that supports the sensor substrate 21 and comes into contact with the flow wall 11. The contact member 22 is formed in a frame or cylindrical shape, with its lower end airtightly surrounding a portion of the surface of the flow wall 11 and its upper end airtightly connected to the sensor substrate 21.

[0031] The sensor substrate 21 is, for example, a printed circuit board. A through-hole 21a is formed in the sensor substrate 21, penetrating in the thickness direction. The through-hole 21a communicates with a pressure chamber 20A formed inside the contact member 22. The first pressure sensor 30 is attached so as to close the through-hole 21a. A pressure-sensitive portion of the first pressure sensor 30 is disposed inside the through-hole 21a.

[0032] The first pressure sensor 30 may be an absolute pressure sensor that can measure a change in pressure in the pressure chamber 20A due to displacement of the flow wall 11, and may employ, for example, a resistive film type, a capacitance type, a piezoelectric element type, an optical type, a MEMS (Micro Electro-Mechanical System) type, etc. The second pressure sensor 41 of the correction device 40, which will be described later, may also be an absolute pressure sensor similar to the first pressure sensor 30.

[0033] The correction device 40 removes at least a portion of the atmospheric pressure noise contained in the output value of the first pressure sensor 30. The correction device 40 includes a second pressure sensor 41 that measures the atmospheric pressure, and a calculation device 42 that applies correction to the output value of the first pressure sensor 30. The second pressure sensor 41 is attached to the upper surface side of the sensor substrate 21, and its pressure-sensitive portion is disposed outside the pressure chamber 20A.

[0034] The arithmetic device 42 is electrically connected to the first pressure sensor 30 and the second pressure sensor 41. The arithmetic device 42 executes arithmetic processing based on a predetermined program and outputs the results to an output device 50 (for example, a display of a personal computer). Specifically, the arithmetic device 42 executes arithmetic processing to correct the output value of the first pressure sensor 30 based on the output value of the second pressure sensor 41 delayed by a certain time.

[0035] Fig. 2 is a diagram showing changes in output values ​​of the first pressure sensor 30 and the second pressure sensor 41 when the inside of the flow channel 10 according to one embodiment is filled with air. Fig. 3 is a diagram showing changes in output values ​​of the first pressure sensor 30 and the second pressure sensor 41 when the inside of the flow channel 10 according to one embodiment is filled with liquid. Note that the output values ​​shown in Figs. 2 and 3 are obtained when there is no fluid flow inside the flow channel 10. The same applies to Figs. 4 to 6 described below.

[0036] 2 and 3, the vertical axis represents pressure [Pa] and the horizontal axis represents time [h]. In Fig. 2 and 3, "detection" indicates the output value of the first pressure sensor 30, and "reference" indicates the output value of the second pressure sensor 41. The same applies to Figs. 4 to 6 described below.

[0037] As shown in Fig. 2, when the inside of the flow path 10 is filled with air, the output values ​​of the first pressure sensor 30 and the second pressure sensor 41 are both affected by atmospheric pressure and change at similar times. On the other hand, as shown in Fig. 3, when the inside of the flow path 10 is filled with liquid, the output values ​​of the first pressure sensor 30 and the second pressure sensor 41 are both affected by atmospheric pressure and change in similar times, but it can be seen that the change in the output value of the first pressure sensor 30 occurs with a certain time delay relative to the change in the output value of the second pressure sensor 41.

[0038] For this reason, the arithmetic unit 42 corrects the output value of the first pressure sensor 30 based on the output value of the second pressure sensor 41 delayed by a certain time. The output value of the second pressure sensor 41 varies due to the influence of the sensor sensitivity, etc. For this reason, the arithmetic unit 42 is programmed to use the moving average of the output values ​​of the second pressure sensor 41 as the correction value.

[0039] Fig. 4 is a diagram showing changes in output values ​​of the first pressure sensor 30 and the second pressure sensor 41 when the inside of the flow path 10 according to one embodiment is filled with liquid, and a moving average of the second pressure sensor 41. Fig. 5 is a diagram showing the difference between the first pressure sensor 30 and the second pressure sensor 41 according to one embodiment, and the difference between the moving averages of the first pressure sensor 30 and the second pressure sensor 41. In Figs. 4 and 5, "reference #" indicates the moving average of the second pressure sensor 41.

[0040] As shown in Fig. 4, "Reference #" is the moving average of the second pressure sensor 41, and therefore lags behind the change in the "reference" output value of the second pressure sensor 41 by a certain time. As shown in Fig. 5, when "detection - reference", i.e., the difference between the first pressure sensor 30 and the second pressure sensor 41, is compared with "detection - reference #", i.e., the difference between the moving average of the first pressure sensor 30 and the second pressure sensor 41, it can be seen that "detection - reference #" has a smaller maximum fluctuation width W. In other words, it can be seen that using the moving average of the second pressure sensor 41 as the correction value improves the accuracy of fluid flow detection compared to using the output value of the second pressure sensor 41 itself as the correction value.

[0041] Fig. 6 is a diagram showing a preferred moving average (time) of the second pressure sensor 41 according to one embodiment. In Fig. 6, the vertical axis represents the fluctuation in the difference between the moving averages of the first pressure sensor 30 and the second pressure sensor within a measurement, i.e., the maximum fluctuation width W shown in Fig. 5, and the horizontal axis represents time [min]. As shown in FIG. 6, it can be seen that the moving average time of the second pressure sensor 41 is preferably set to 30 to 300 minutes, at which point the maximum fluctuation width W becomes small. The above-mentioned moving average is a simple moving average that does not weight the output value of the second pressure sensor 41. Therefore, for example, if the moving average time of the second pressure sensor 41 is set to 150 minutes, at which point the maximum fluctuation width W becomes smallest, it takes 150 minutes to calculate the simple moving average, resulting in a value delayed by 150 minutes (a fixed time). By using this as the reference value (correction value) of the first pressure sensor 30, which is measured in real time, it is possible to eliminate the time lag caused by the influence of atmospheric pressure shown in FIG. 3.

[0042] As described above, the flow detection device 1 of this embodiment comprises a flow path 10 having a flow wall 11 that expands and contracts due to pressure changes in the fluid flowing therethrough, a pressure chamber forming portion 20 that forms a pressure chamber 20A that covers at least a portion of the periphery of the flow wall 11, a first pressure sensor 30 that measures changes in pressure in the pressure chamber 20A due to displacement of the flow wall 11, and a correction device 40 that removes at least a portion of the atmospheric pressure noise contained in the output value of the first pressure sensor 30, and the correction device 40 comprises a second pressure sensor 41 that is arranged outside the pressure chamber 20A and measures the atmospheric pressure, and a calculation device 42 that applies correction to the output value of the first pressure sensor 30 based on the output value of the second pressure sensor 41 delayed by a certain time. According to this configuration, the first pressure sensor 30 measures the change in pressure in the pressure chamber 20A surrounding the flow wall 11 of the flow path 10, and the second pressure sensor 41 measures the change in atmospheric pressure. Based on the measurement result of the second pressure sensor 41, a correction is made to the first pressure sensor 30 with a certain time delay, thereby improving the accuracy of fluid flow detection.

[0043] Furthermore, in the flow detection device 1 of this embodiment, the calculation device 42 uses as a correction value the moving average of the output value of the second pressure sensor 41, which is delayed by a certain time from the output value of the first pressure sensor 30. According to this configuration, by using the moving average of the output value of the second pressure sensor 41 as the correction value, the difference in the output value of the second pressure sensor 41 is stabilized, thereby reducing atmospheric pressure noise contained in the output value of the first pressure sensor 30 and further improving the accuracy of fluid flow detection.

[0044] In the flow detection device 1 of this embodiment, the moving average time is set to 30 minutes to 300 minutes. With this configuration, the difference in the output value of the second pressure sensor 41 becomes more stable.

[0045] In the flow detection device 1 of this embodiment, the flow path 10 has an inner diameter D1 and an outer diameter D2, where D2≧10×D1. This configuration enables accurate detection of the flow of a fluid in a flow path 10 having a thick flow wall 11, where the difference between the inner diameter and the outer diameter is 10 times or more.

[0046] In the flow detection device 1 of this embodiment, the inner diameter of the flow channel 10 is 1 mm or less. With this configuration, the flow of the fluid can be detected with high accuracy in the small flow channel 10 with an inner diameter of 1 mm or less.

[0047] Furthermore, in the flow detection device 1 of this embodiment, the flow channel 10 is made of an elastomer. With this configuration, the flow of the fluid can be detected with high accuracy in the flow channel 10 made of an elastomer.

[0048] Furthermore, in the flow detection device 1 of this embodiment, the flow channel 10 is made of polyvinyl chloride. According to this configuration, the flow of the fluid can be detected with high accuracy in the flow channel 10 made of polyvinyl chloride.

[0049] Furthermore, a correction method for a flow detection device 1 according to this embodiment is a correction method for removing at least a portion of atmospheric pressure noise contained in the output value of the first pressure sensor 30 in a flow detection device 1 including a flow path 10 having a flow wall 11 that expands and contracts due to pressure changes in the fluid flowing therein, a pressure chamber forming portion 20 that forms a pressure chamber 20A that covers at least a portion of the periphery of the flow wall 11, and a first pressure sensor 30 that measures changes in pressure in the pressure chamber 20A due to displacement of the flow wall 11. The correction method includes disposing a second pressure sensor 41 outside the pressure chamber 20A to measure atmospheric pressure, and correcting the output value of the first pressure sensor 30 based on the output value of the second pressure sensor 41 that is delayed by a fixed time. With this configuration, the first pressure sensor 30 measures changes in pressure in the pressure chamber 20A that surrounds the flow wall 11 of the flow path 10, and the second pressure sensor 41 measures changes in atmospheric pressure, and correcting the first pressure sensor 30 based on the measurement result of the second pressure sensor 41 with a fixed time delay, thereby improving the accuracy of fluid flow detection.

[0050] While preferred embodiments of the present invention have been described and illustrated, it should be understood that these are illustrative of the present invention and should not be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the scope of the present invention. Accordingly, the present invention should not be deemed limited by the foregoing description, but rather by the scope of the claims.

[0051] For example, the inner diameter of the flow channel 10 may be 0.2 mm to 1.3 mm, and the outer diameter may be 3.0 mm to 6.0 mm. [Explanation of symbols]

[0052] 1. Flow detection device 10 Flow path 11 Flowing wall 20 Pressure chamber forming section 20A pressure chamber 21 Sensor board 21a Through hole 22 Contact member 30 First pressure sensor 40 Correction Device 41 Second pressure sensor 42 Arithmetic unit 50 Output Device O center axis

Claims

1. a flow path having a flow wall that expands and contracts in response to a pressure change of a fluid flowing therethrough; a pressure chamber forming portion that forms a pressure chamber that covers at least a portion of the periphery of the flow wall; a first pressure sensor that measures a change in pressure in the pressure chamber due to a displacement of the flow wall; a correction device that removes at least a portion of atmospheric pressure noise included in the output value of the first pressure sensor, The correction device a second pressure sensor disposed outside the pressure chamber and configured to measure atmospheric pressure; a calculation device that corrects the output value of the first pressure sensor based on the output value of the second pressure sensor delayed by a certain time, Flow detection device.

2. the calculation device sets a moving average of the output value of the second pressure sensor delayed by the certain time with respect to the output value of the first pressure sensor as a correction value. The flow sensing device of claim 1 .

3. The moving average time is set to 30 minutes to 300 minutes. The flow sensing device of claim 2 .

4. When the inner diameter of the flow path is D1 and the outer diameter is D2, D2 ≧ 10 × D1 have a relationship of A flow detection device according to any one of claims 1 to 3.

5. The inner diameter of the flow path is 1 mm or less. A flow detection device according to any one of claims 1 to 3.

6. The flow path is formed from an elastomer. A flow detection device according to any one of claims 1 to 3.

7. The flow path is formed from polyvinyl chloride. A flow detection device according to any one of claims 1 to 3.

8. a flow path having a flow wall that expands and contracts in response to a pressure change of a fluid flowing therethrough; a pressure chamber forming portion that forms a pressure chamber that covers at least a portion of the periphery of the flow wall; a first pressure sensor that measures a change in pressure in the pressure chamber due to a displacement of the flow wall; In a flow detection device comprising: a correction method for removing at least a portion of atmospheric pressure noise included in an output value of the first pressure sensor, a second pressure sensor disposed outside the pressure chamber to measure atmospheric pressure; The output value of the first pressure sensor is corrected based on the output value of the second pressure sensor delayed by a certain time. A method for correcting a flow detection device.

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