Substitute Pitot tube and drying booth

Abstract

This invention provides a substitute Pitot tube that ensures sufficient measurement accuracy when measuring wind speed and is less expensive than a standard Pitot tube. [Solution] The substitute Pitot tube 6 comprises a first pipe 11 with a first hole 11a, a second pipe 12 with a second hole 12a adjacent to the first hole 11a, and a measuring instrument 13 for measuring the pressure difference between the inside of the first pipe 11 and the inside of the second pipe 12. The hole axis 11aa of the second hole 12a is inclined to the hole axis 12aa of the first hole 11a within a range of 90° to 180°. In this substitute Pitot tube 6, because the first hole 11a and the second hole 12a are adjacent, the measuring instrument 13 can determine a nearly accurate dynamic pressure as the pressure difference, thus ensuring sufficient measurement accuracy when measuring wind speed. Furthermore, since the first pipe 11 and the second pipe 12 are separate components, the processing of both pipes 11 and 12 is easier, making it cheaper than a traditional Pitot tube.

Description

Technical Field

[0001] The present disclosure relates to a substitute Pitot tube that substitutes for a Pitot tube, and a drive booth equipped with the substitute Pitot tube.

Background Art

[0002] A drive booth is a dry dust collection device that uses a high-efficiency filter such as a cardboard filter, and has a function of collecting paint mist generated during the painting of a workpiece. Patent Document 1 discloses an example of a drive booth.

[0003] The drive booth disclosed in Patent Document 1 (referred to as a paint mist removal device in the same document) is installed in a painting booth for painting automobile parts, and collects paint mist in the air discharged from the painting booth. The drive booth includes a duct connected to the painting booth, and a plurality of filters arranged along the wind direction (air flow direction) in the duct. The air in the painting booth is drawn into the duct by a fan, and the paint mist in the air is collected by the filters in the duct.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a drying booth, if the filter becomes clogged with paint mist, it needs to be replaced. The timing for filter replacement is determined, for example, based on the pressure loss caused by the filter. As paint mist accumulates in the filter, the resistance caused by the filter gradually increases, and the pressure loss increases. Therefore, when the pressure loss exceeds a predetermined value, it can be determined that it is time to replace the clogged filter, and it is replaced with a new filter.

[0006] In some cases, multiple dry booths may be operated simultaneously. In this case, a common fan may be used to draw air into the ducts of each of the multiple dry booths. However, when this configuration is adopted, there is a problem in that it becomes difficult to determine which of the multiple dry booths' filters needs to be replaced, for the following reasons.

[0007] In the above configuration, multiple drying booths contain a mix of (1) drying booths where the filter is clogged with paint mist and the filter needs to be replaced, and (2) drying booths where the filter has ample clearance and does not need to be replaced. In this case, it is difficult to distinguish between the two based on pressure loss as described above. This is because in drying booth (1), resistance increases and the pressure loss due to the filter increases, while in drying booth (2), the air velocity (air flow rate) increases and the pressure loss due to the filter also increases, making it difficult to distinguish between the two.

[0008] Therefore, determining which drying booth's filter needs replacing requires measuring the degree of clogging in each booth's filter to determine if it's completely worn out, which results in a significant amount of work. As a solution to this problem, it is conceivable to measure the airflow velocity downstream of the filter in addition to the pressure loss caused by the filter. This is because as paint mist accumulates in the filter, the airflow velocity downstream of the filter gradually decreases, allowing for the determination of whether or not the filter is clogged by measuring the airflow velocity.

[0009] For measuring wind speed, it is conceivable to use a Pitot tube, such as the one disclosed in Patent Document 2. However, while Pitot tubes have the advantage of high measurement accuracy, they have the disadvantage of being expensive. Therefore, if there are many drying booths and many locations where wind speed needs to be measured, the equipment costs will be enormous.

[0010] Furthermore, since paint mist does not accumulate rapidly on the filter, the wind speed does not change rapidly either. Moreover, even if a clogged filter cannot be replaced immediately, it does not significantly negatively affect the quality of automotive parts, etc. In other words, when measuring wind speed, the high measurement accuracy of a Pitot tube is not necessarily required.

[0011] Therefore, there was a need for a substitute that could ensure sufficient measurement accuracy, even if it was inferior to that of a Pitot tube, and that was also cheaper than a Pitot tube. In light of the above circumstances, the problem to be solved is to provide a substitute Pitot tube that can ensure sufficient measurement accuracy when measuring wind speed and is cheaper than a Pitot tube. [Means for solving the problem]

[0012] A first substitute Pitot tube for solving the above problems comprises a first pipe with a first hole, a second pipe with a second hole adjacent to the first hole, and a measuring instrument for measuring the pressure difference between the inside of the first pipe and the inside of the second pipe, characterized in that the hole axis of the second hole is inclined with respect to the hole axis of the first hole within a range of 90° to 180°.

[0013] In the first substitute Pitot tube, wind speed can be measured by aligning either the first hole of the first pipe or the second hole of the second pipe with the wind direction. Here, we will explain how wind speed can be measured using the case where the first hole of the first pipe is aligned with the wind direction as an example. Since the first hole of the first pipe is aligned with the wind direction, the gas flowing into the first pipe from the first hole has total pressure (static pressure + dynamic pressure). On the other hand, since the axis of the second hole of the second pipe is inclined between 90° and 180° relative to the axis of the first hole, the gas in the second pipe has only static pressure. Here, since the first and second holes are adjacent, the static pressure values ​​between the gas in the first pipe and the gas in the second pipe are approximately the same. As a result, the pressure difference between the first and second pipes measured by the measuring instrument (the difference between the total pressure of the gas in the first pipe and the static pressure of the gas in the second pipe) is approximately equivalent to the dynamic pressure of the gas in the first pipe, as the static pressure values ​​cancel each other out. The wind speed is then measured based on the pressure difference (a value roughly equivalent to dynamic pressure). In this substitute Pitot tube, as mentioned above, the first and second holes are adjacent to each other, allowing for the calculation of the dynamic pressure with approximate accuracy. As a result, while the measurement accuracy is lower than that of a Pitot tube, sufficient measurement accuracy can be ensured when measuring wind speed. Furthermore, since the first and second pipes of this substitute Pitot tube are separate components, the processing of each pipe is simplified. Consequently, it is possible to make it less expensive than a Pitot tube.

[0014] The second substitute pitot tube is a modified version of the first substitute pitot tube described above, in which the first pipe has multiple first holes spaced apart from each other, and the second pipe has the same number of second holes spaced apart from each other as the first holes.

[0015] The second substitute Pitot tube offers advantages in measuring average wind speed. For example, within a duct, the wind speed differs between the central and inner wall sections of the duct's flow path cross-section. When wind speed varies depending on the location on the flow path cross-section, it is sometimes necessary to know the average wind speed. In this substitute Pitot tube, the first hole in the first pipe and the second hole in the second pipe are provided in multiple locations spaced apart from each other, making it easier to obtain the average wind speed. Specifically, the average wind speed of the gas flowing into each of the multiple first holes can be measured (when the multiple first holes are oriented opposite the wind direction).

[0016] The first or second substitute pitot tube described above can be installed in a drying booth. The drying booth comprises a duct, a filter placed inside the duct, and the first or second substitute pitot tube located downstream of the filter inside the duct, with either the first or second hole opening facing upstream.

[0017] According to the above-mentioned drying booth, in addition to measuring pressure loss due to the filter, it is possible to determine whether the filter is clogged by measuring the airflow velocity using a substitute Pitot tube. Therefore, it is possible to appropriately determine when the filter should be replaced. Furthermore, since the effort required to determine whether the filter is clogged is eliminated, the labor required for determination can be significantly reduced. This also helps to reduce the running costs of the drying booth. In addition, because it is possible to appropriately determine when the filter should be replaced, it becomes easier to plan the production of new filters. [Effects of the Invention]

[0018] The substitute Pitot tube of this disclosure can ensure sufficient measurement accuracy when measuring wind speed and can be made less expensive than a Pitot tube. [Brief explanation of the drawing]

[0019] [Figure 1] This is a cross-sectional view showing multiple drying booths installed in a dust collection device. [Figure 2] It is a cross-sectional view showing a substitute Pitot tube. [Figure 3] It is a perspective view showing a substitute Pitot tube.

Embodiment for Carrying out the Invention

[0020] Hereinafter, embodiments of a substitute Pitot tube and a drive booth will be described with reference to the accompanying drawings. The X direction, Y direction, and Z direction shown in each drawing referred to in the description of the embodiments are directions orthogonal to each other.

[0021] The dust collector 1 is shown in FIG. 1. The dust collector 1 includes a plurality of drive booths 2 and a fan 3 shared among the plurality of drive booths 2. Each drive booth 2 provided in the dust collector 1 is installed adjacent to a painting booth (not shown) for painting automobile parts, and collects paint mist in the air discharged from the painting booth as the fan 3 operates.

[0022] In the present embodiment, there are two dust collectors 1 shown in FIG. 1, and a painting booth exists between one and the other of the two. Since the configurations of the two dust collectors 1 are the same, in the following description, only the configuration of one of the two will be described.

[0023] Each of the plurality of drive booths 2 includes a duct 4 connected to both the painting booth and the fan 3, a plurality of filters 5 arranged along the wind direction (the direction indicated by the dashed arrow in FIG. 1) in the duct 4, and a substitute Pitot tube 6 arranged on the downstream side of the plurality of filters 5 in the duct 4.

[0024] When the fan 3 operates, the duct 4 draws in air containing paint mist from the painting booth, and sends the drawn air to the fan 3 side while passing it through the plurality of filters 5. In FIG. 1, only a part of the duct 4 is shown, and the section shown in the figure extends in the vertical direction (Z direction). The wind direction (the flow direction of air) in the section is upward. This section also serves as a filter case for accommodating the plurality of filters 5.

[0025] In this embodiment, the multiple filters 5 include, in order from the upstream side of the airflow, four cardboard filters 7, a cleansing filter 8, a pre-filter 9, and a medium-efficiency filter 10. Of course, the types and number of filters 5 arranged in the duct 4 are not limited to this embodiment. Paint mist in the air passing through the duct 4 is mainly collected by the four cardboard filters 7.

[0026] Pressure gauges (not shown) are positioned at position A between the Clinselt 8 and the pre-filter 9, and at position B between the medium-efficiency filter 10 and the substitute Pitot tube 6. The pressure gauges are capable of measuring the differential pressure between atmospheric pressure and the pressure at position A or position B. Based on the differential pressure measured by the pressure gauges, the pressure loss through the four cardboard filters 7 and the Clinselt 8, and the pressure loss through the pre-filter 9 and the medium-efficiency filter 10 can be determined.

[0027] Figures 2 and 3 show a substitute Pitot tube 6. The substitute Pitot tube 6 measures the wind speed at the position where it is placed in the airflow path. The substitute Pitot tube 6 comprises a first pipe 11 with a first hole 11a, a second pipe 12 with a second hole 12a adjacent to the first hole 11a, and a measuring instrument 13 (not shown in Figure 3) for measuring the pressure difference between the inside of the first pipe 11 and the inside of the second pipe 12.

[0028] The first pipe 11 and the second pipe 12 are separate pipes independent of each other. While not limiting the cross-sectional shape of both pipes 11 and 12, in this embodiment, both pipes 11 and 12 have a circular cross-sectional shape. Both pipes 11 and 12 are arranged parallel to each other, and both extend horizontally (in the X direction). In the Y direction, both pipes 11 and 12 are positioned away from the inner wall surface 4a of the duct 4. Each of the pipes 11 and 12 has a structure in which a straight tube 14, an L-shaped tube 15, and a T-shaped tube 16 are connected. For example, commercially available quick-connect fittings can be used as the straight tube 14, L-shaped tube 15, and T-shaped tube 16.

[0029] The first pipe 11 has three first holes 11a spaced apart from each other. The hole axis 11aa of each first hole 11a extends in the vertical direction, and each first hole 11a opens facing vertically downward. In other words, each first hole 11a opens facing the wind direction within the duct 4 (indicated by the white arrows in Figure 3). To put it another way, each first hole 11a opens facing the upstream side of the wind direction. Depending on the direction of the opening of the first holes 11a, the air flowing into the first pipe 11 from the first holes 11a has total pressure (static pressure + dynamic pressure).

[0030] Of the three first holes 11a, the two at the ends are located near the inner wall surface 4a in the flow path cross-section of the duct 4. On the other hand, the central first hole 11a is located near the center 4b in the flow path cross-section of the duct 4. Although the arrangement of the first holes 11a is not limited, in this embodiment, the two at the ends are arranged symmetrically in the X direction with respect to the central first hole 11a. The two at the ends allow air near the inner wall surface 4a, where the air velocity is relatively slow, to flow into the first pipe 11, while the central first hole 11a allows air near the center 4b, where the air velocity is relatively fast, to flow into the first pipe 11.

[0031] The second pipe 12 is positioned substantially the same as the first pipe 11 in the airflow path. In other words, in this embodiment, both the first pipe 11 and the second pipe 12 are positioned substantially the same in the vertical direction.

[0032] The second pipe 12 is provided with three second holes 12a spaced apart from each other. Therefore, the number of second holes 12a in the second pipe 12 is the same as the number of first holes 11a in the first pipe 11. Each second hole 12a is paired with one of the three first holes 11a, and the paired first hole 11a and second hole 12a are adjacent in the Y direction.

[0033] The hole axis 12aa of each second hole 12a extends vertically, and each second hole 12a opens facing vertically upward. In other words, each second hole 12a opens facing the same direction as the airflow within the duct 4, opposite to each first hole 11a, and the hole axis 12aa of each second hole 12a is inclined at 180° with respect to the hole axis 11aa of each first hole 11a. In other words, each second hole 12a opens facing downstream of the airflow. Due to the direction of the opening of the second hole 12a, the air inside the second pipe 12 has only static pressure. Note that the inclination of the hole axis 12aa of the second hole 12a with respect to the hole axis 11aa of the first hole 11a is not limited to 180°, but may be any angle in the range of 90° to 180°.

[0034] Similar to the three first holes 11a described above, of the three second holes 12a, the two at both ends are located near the inner wall surface 4a in the flow path cross-section of the duct 4. On the other hand, the central second hole 12a is located near the center 4b in the flow path cross-section of the duct 4. Although the arrangement of the second holes 12a is not limited, in this embodiment, the two second holes 12a at both ends are arranged symmetrically in the X direction with respect to the central second hole 12a.

[0035] The inner diameters of the first pipe 11 and the second pipe 12 (the inner diameters of the straight tube 14, the L-shaped tube 15, and the T-shaped tube 16) are, for example, about 10 mm. The length of the first pipe 11 and the second pipe 12 in the X direction is shorter than the width in the X direction of the flow path cross-section of the duct 4. The distance D in the Y direction between the first pipe 11 and the second pipe 12 (equal to the distance in the Y direction between the hole axis 11aa and the hole axis 12aa) is, for example, about 30 mm.

[0036] Here, it is preferable to make the separation distance D as short as possible. This is to ensure that the static pressure between the air in the first pipe 11 and the air in the second pipe 12 is approximately the same when measuring the wind speed with the substitute Pitot tube 6.

[0037] The measuring instrument 13 in this embodiment is a differential pressure gauge. The measuring instrument 13 calculates the difference between the total pressure (static pressure + dynamic pressure) of the air in the first pipe 11 and the static pressure of the air in the second pipe 12 as the pressure difference described above.

[0038] Since the first hole 11a and the second hole 12a are adjacent to each other between the first pipe 11 and the second pipe 12, the static pressure values ​​between the air in the first pipe 11 and the air in the second pipe 12 are approximately the same. Therefore, the pressure difference measured by the measuring instrument 13 is approximately equivalent to the dynamic pressure of the air in the first pipe 11. The wind speed is then measured based on this pressure difference. Specifically, the average wind speed of the air flowing into each of the three first holes 11a is measured.

[0039] As shown in Figure 1, the fan 3 is connected to a duct 4 provided in each of the multiple drying booths 2. As a result, when the fan 3 is in operation, air is drawn from the paint booth into the ducts 4 of all the drying booths 2.

[0040] In the dust collector 1 described above, the timing for replacing the cardboard filter 7 in each of the multiple drying booths 2 can be determined as follows. Specifically, when the pressure loss due to the four cardboard filters 7 and the cleanselter 8 exceeds a predetermined set value, and the air velocity measured by the substitute pitot tube 6 falls below a predetermined set value, it can be determined that the cardboard filter 7 is clogged, and it is time to replace it.

[0041] Herein, the following modifications can be applied to the above embodiment. In the above embodiment, each of the multiple drying booths 2 is equipped with a measuring instrument 13, and the number of drying booths 2 and the number of measuring instruments 13 are equal. However, as a modification of the above embodiment, one measuring instrument 13 may be shared among multiple drying booths 2. In other words, [number of drying booths 2]:[number of measuring instruments 13] = multiple:1 may be used. In this way, equipment costs can be reduced by sharing the measuring instrument 13.

[0042] Here, as an example of a configuration in which one measuring instrument 13 is shared among multiple drying booths 2, we show a case in which one measuring instrument 13 is shared among eight drying booths 2. In this configuration, one measuring instrument 13 is shared among eight sets of first pipes 11 and second pipes 12. In this case, eight air passages are provided connecting the eight sets of first pipes 11 and second pipes 12 and the shared measuring instrument 13, and a valve can be provided in each of the eight passages. Furthermore, it is possible to open only the valve of the passage corresponding to the set of first pipes 11 and second pipes 12 used for wind speed measurement. Alternatively, the valves that are opened may be switched at regular intervals, and the set of eight sets used for wind speed measurement may be switched at regular intervals. [Explanation of Symbols]

[0043] 2 Dry Booths 4 ducts 5 filters 6 Substitute Pitot tubes 7 Cardboard filter 8 Klinselter 9 Pre-filter 10 Medium-efficiency filters 11 First Pipe 11a First hole 11aa hole axis 12 Second pipe 12a Second hole 12aa hole axis 13 Measuring instruments

Claims

1. It is a substitute Pitot tube, A first pipe with a first hole, A second pipe having a second hole adjacent to the first hole, A measuring instrument for measuring the pressure difference between the inside of the first pipe and the inside of the second pipe, Equipped with, A substitute Pitot tube characterized in that the hole axis of the second hole is inclined within a range of 90° to 180° with respect to the hole axis of the first hole.

2. The first pipe is provided with a plurality of first holes spaced apart from each other. The substitute Pitot tube according to claim 1, characterized in that the second pipe is provided with the same number of second holes as the first holes, spaced apart from each other.

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