WO2004111579A1

WO2004111579A1 - Flowmeter

Info

Publication number: WO2004111579A1
Application number: PCT/JP2003/007494
Authority: WO
Inventors: Hwa-Soo Lee; Takazou Yamada; Sakari Yokoyama
Original assignee: Nihon University
Priority date: 2003-06-12
Filing date: 2003-06-12
Publication date: 2004-12-23
Also published as: JPWO2004111579A1; JP4537314B2; AU2003242336A1

Abstract

A flowmeter comprising a case having an inflow channel and an outflow channel of fluid, an impeller being contained and supported rotatably in the case while having a blade part on the outer circumference of a disc part and receiving fluid flowing in from the inflow channel to rotate depending on the flow rate, and means for detecting the number of revolutions of the impeller and measuring the flow rate based on the number of revolutions of the impeller, characterized in that the means for detecting the number of revolutions of the impeller comprises a detection object part provided by machining the surface of the disc part, and a tool capable of noncontact detection of the detection object part fixed to the case.

Description

Specification

Technical field

The present invention relates to a flow meter for measuring a flow rate of a fluid such as paint. Background art

As a conventional flowmeter, for example, there is one shown in FIG. 12 described in Japanese Patent Publication No. 56-512282. FIG. 12 is a cross-sectional view of a flow channel in which a flow meter is arranged. As shown in FIG. 12, an impeller 105 is arranged in a flow path 103 constituted by a tube 101. An electric motor 107 is connected to the impeller 105. The electric motor 107 is connected to a constant voltage power supply 109. A current detector 111 is connected to the motor 107 and the constant voltage power supply 109. The indicator 1 1 3 is connected to the current detector 1 1 1. Therefore, the electric motor 107 is driven at a constant voltage by the constant voltage power supply 109. In this state, when a change occurs in the flow rate of the airflow in the flow path 103, the load current of the electric motor 107 changes. This change is detected as a change in the current value by the current detector 111, converted into a voltage, and output to the display 113. The display unit 113 can display a flow rate change according to the voltage conversion. However, in the above flowmeter, since the rotation axes of the impeller 105 and the motor 107 are arranged in the direction along the fluid flow, the entire impeller 105 and the motor 107 are The impeller 105 is disposed in the flow path 103 and the impeller 105 faces the flow direction. For this reason, measurement may be difficult when the flow rate is small.

That is, in the above flow meter, the kinetic energy of the fluid is transferred to the impeller 105 The flow rate is measured by applying the force, but the kinetic energy in the flow direction of the fluid is converted into the orthogonal rotation of the impeller 105, so the waste of kinetic energy acting on the impeller 105 from the fluid is reduced. In many cases, it is difficult to measure a very small flow rate, or a large error may occur.

In addition, in the above flowmeter, since the entire impeller 105 and the like are housed in the flow passage 103 as shown in FIG. 12, the flow passage 103 becomes thicker. Flow measurement involves difficulties.

Generally, a mobile phone housing, a cosmetic container, or a toy is sprayed with a spray gun to paint in various colors. In this case, there is a case where the paint is pumped from one pump to a plurality of spray guns. The pump and each spray gun are connected by relatively thin tubes, and the paint is pumped from the pump to each spray gun through each tube. The flow rate of paint that is pumped from one pump to each spray gun is basically the same if the channel length is the same.

However, depending on the arrangement of the pump and each spray gun, the length of the tube from the pump to each spray gun may be different, and the flow rate reaching each spray gun may be different due to the difference in flow path length . If paint is sprayed from each spray gun in such a state, there is a possibility that remarkable unevenness of coating may be caused for each object to be coated due to a flow rate error of each spray gun. Therefore, it is important to measure the flow rate of paint that is pumped to each spray gun and spray the paint while adjusting the flow rate for each spray gun.

In such a case, an example of the flow rate of the paint in the pipe is about 50 m1 Zmin, for example, about a water drop dropped when a water tap is closed. As described above, it is extremely difficult or extremely error-prone to measure the flow rate of a paint having such a small flow rate with a flow meter as shown in FIG. Therefore, when a flow meter as shown in Fig. 11 is used, there is a possibility that the coating unevenness cannot be improved even though the paint is sprayed while measuring the flow rate. When the electric motor 107 is arranged in the flow passage 103 as shown in FIG. 12, in the case of a paint or the like, the heat generated by the electric motor 107 and the spa There is also a possibility that a fire may occur due to the action of one stroke.

On the other hand, there is a flow meter as shown in FIG. 13 described in Japanese Patent Application Laid-Open No. 7-55514. In this flowmeter, an impeller 2 17 is rotatably supported in a case 2 15 and a magnet 2 19 is built in the impeller 2 17. In contrast to the magnet 219, the shaft part 221 contains, for example, a Hall element 223.

The impeller 2 17 receives the fluid flowing from the opening 2 24 and rotates, and the Hall element 2 23 detects the rotation of the magnet 2 19 to measure the flow rate.

In this flow meter, the fluid flowing from the opening 222 is received in the rotating direction by the blades 222 of the impeller 21 as compared with the flow meter of FIG. It can be said that the flow energy can be efficiently transmitted as the rotation of the impeller 217 and the flow path resistance can be reduced, which is suitable for measuring a small flow rate. Also, since the motor is not arranged in the flow path, there is no risk of fire.

However, in the flowmeter shown in Fig. 13, the magnet 219 is embedded in the impeller 2 17, which imposes a limit on the weight reduction of the impeller 2 17, and as described above, the minute flow rate of paint etc. There is a limit to improving the accuracy of the measurement.

In addition, if a structure incorporating the magnet 219 as shown in FIG. 13 is used, it is difficult to balance the weight in the rotational direction, and the imbalance in rotation will limit the accuracy of measurement.

Furthermore, if the number of magnets 219 is increased in order to improve the measurement accuracy, the weight of the entire impeller 217 increases by that much, and the measurement of minute flow rate becomes more and more difficult. Disclosure of the invention

An object of the present invention is to provide a flow meter that can measure a flow rate of a minute flow rate easily and accurately.

An object of the present invention is to provide a case having a fluid inflow path and a fluid outflow path, and a vane portion provided on the outer periphery of a disk portion. A flowmeter for measuring a flow rate based on the rotation speed of the impeller, comprising: an impeller that rotates in accordance with a receiving flow rate at a section; and a rotation speed detection unit that detects a rotation speed of the impeller. The rotation number detecting means includes: a detection target portion provided by a change in the surface state of the disk portion; and a detection tool attached to the case and capable of detecting the detection target portion in a non-contact manner. Achieved. Therefore, it is not necessary to set the detection target part by changing the surface form of the disk part and to embed the magnet in the impeller, so that the weight of the impeller can be reduced and the moment of inertia can be reduced, and the rotational imbalance can be reduced. Can be suppressed. Further, even if the number of detection target parts is increased to improve the measurement accuracy, only the change in the surface form is replaced. Therefore, it is possible to suppress the increase in the weight of the impeller and the increase in the moment of inertia.

By reducing the moment of inertia, suppressing the increase in weight, and suppressing the rotational imbalance, not only normal flow rate measurement but also minute flow rate measurement can be performed easily and accurately.

In the flowmeter according to the present invention, the detection target portion is provided by processing a concave portion or a hole portion in the disk portion.

Therefore, even if the number of parts to be detected is increased to improve detection accuracy, only a recess or hole is formed in the disk part, so there is no increase in the weight of the impeller, and the increase in the moment of inertia is reliably suppressed, and the normal flow rate Not only the measurement, but also the measurement of minute flow rate can be performed easily and accurately.

In the flow meter according to the present invention, the inflow path of the fluid is disposed to face the blade section, and the outflow path is disposed to face the rotation center of the disk section. Therefore, even if bubbles generated by the rotation of the impeller gather at the rotation center side of the impeller due to the difference in specific gravity with the fluid, the bubbles can be smoothly discharged from the outflow passage arranged opposite to the rotation center of the disk part. it can. For this reason, if bubbles are present, the impeller receives rotational resistance against the case due to surface tension and the like, which may adversely affect the flow rate measurement of the minute flow rate.The smooth discharge of the bubbles suppresses the effects of the bubbles. However, not only normal flow rate measurement but also minute flow rate measurement can be performed easily and accurately.

The flow meter according to the present invention is provided with display means for displaying the flow rate based on the number of revolutions, wherein the inflow path and the outflow path are connected to a supply path for supplying paint to a spray gun for painting.

Therefore, the flow rate of the paint at a minute flow rate flowing through the supply path can be displayed without difficulty by the display means. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an overall schematic configuration diagram of a coating apparatus provided with a flow meter according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a flow meter main body according to an embodiment of the present invention, as viewed from a plane.

FIG. 3 is a sectional view taken along the line SA-SA in FIG.

FIG. 4 is an enlarged sectional view of a main part of a flow meter main body according to one embodiment of the present invention. FIG. 5 is a plan view of an impeller of the flow meter main body according to one embodiment of the present invention. The figure is a cross-sectional view of the impeller of the flowmeter main body according to one embodiment of the present invention. FIG. 7 is a graph showing the experimental results of the embodiment of the present invention.

FIG. 8 shows a flowmeter main body according to another embodiment of the present invention, which is FIG.

FIG. 9 is a cross-sectional view taken along the line SB-SB in FIG.

FIG. 10 is a cross-sectional view of a flow meter main body according to still another embodiment of the present invention viewed from a plane.

FIG. 11 is a cross-sectional view taken along the line SC-SC in FIG.

FIG. 12 is a schematic diagram of a flow meter according to a conventional example.

FIG. 13 is a sectional view of a main part of a flow meter according to another conventional example. BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 shows an overall schematic configuration diagram of a coating apparatus to which a flow meter according to an embodiment of the present invention is applied.

As shown in FIG. 1, the coating apparatus 1 includes a spray gun 3, a pump 5, and a coating tank 7, and has a flow meter 9 between the spray gun 3 and the pump 5. That is, the flow meter 9 according to the embodiment of the present invention is applied to the coating apparatus 1, and the fluid to be measured by the flow meter 9 is a paint.

The spray gun 3 is for spraying paint on a housing of a mobile phone, a container for cosmetics, a toy or the like, which is an object to be painted. The spray gun 3 is provided with an adjustment dial 11 for finely adjusting the spray amount. By adjusting the adjustment dial 11, the squeeze in the spray gun 3 can be adjusted and the spray amount can be adjusted. The spray gun 3 is connected to the outlet of the flow meter 9 via a tube 13 which constitutes a paint supply path, and is pumped through a tube 15 which constitutes a paint supply path to the inflow passage of the flow meter 9. 5 is connected. The pump 5 is connected to the paint tank 7 via a pipe 17.

Each of the tubes 13 and 15 is, for example, a Teflon tube whose diameter is as small as 4 to 6 mm, and the flow rate of the flowing paint is a minute flow rate. For example, the flow rate in the tubes 13 and 15 is 50 m1 Zmin, and the internal pressure is :! Has become a ~ 1 5 kg / cm ² about..

The tube 13 is supported on a support 21 by a holding member 19. The holding member 19 can adjust the vertical height with respect to the support column 21 by loosening the handle 23.

The column 21 supports the flowmeter 9. The flow meter 9 has a display 25 on a housing 25. The display section 27 is adapted to digitally display the measured flow value.

While the spray guns 3 are connected in large numbers, the pump 5 is provided, for example, with one pump, and each of the spray guns 3 is connected to the respective spray guns 3 via separate tubes 15, 13,. , …It is connected to the. A flow meter 9 is also provided for each spray gun 3,. However, it is also possible to arrange one spray gun 3 and one flow meter 9 for one pump 5 and to have a configuration in which many of these combinations are connected.

The flow meter 9 will be further described with reference to FIGS. FIG. 2 is a cross-sectional view of a flow meter main body according to an embodiment of the present invention viewed from a plane, FIG. 3 is a cross-sectional view taken along line SA-SA of FIG. 2, and FIG. Fig. 5 is an enlarged sectional view, Fig. 5 is a plan view of the impeller, and Fig. 6 is a sectional view of the impeller. In FIG. 2, the sectional positions of the upper half and the lower half are different.

FIG. 2 and FIG. 3 show the flow meter main body 29 fixed in the housing 25. The flowmeter main body 29 includes a case 31, an impeller 33, and a proximity sensor 35 as rotation speed detecting means. In this embodiment, the flow meter body 29 is supported in the housing 25 so that the impeller 33 rotates horizontally. However, the arrangement state of the flow meter body 29 is not particularly limited, and the impeller 33 can be arranged so as to rotate in the vertical direction. As shown in FIGS. 1 is made of a light metal such as aluminum and has high chemical resistance and light weight. Case 3 1 The base part 37 and the lid part 39 are combined.

The base portion 37 is provided with a female screw portion 41 for fastening in a square shape. An accommodation recess 43 having a circular cross section is provided at the center of the base portion 37. A support hole 45 is provided at the center of the accommodation recess 43. On one side of the accommodating recess 43, an escape recess 46 is provided to face the proximity sensor 35. A seal groove 47 is provided around the outer periphery of the housing recess 43 in a circular shape. The base portion 37 is provided with an inflow channel 49 and an outflow channel 51, and the inflow channel 49 and the outflow channel 51 are formed so as to communicate with the housing recess 43. The inflow path 49 and the outflow path 51 are arranged so as to be mutually linear along the tangential direction of the rotating circle of the impeller 33. The inner diameter and the arrangement position of the inflow channel 49 are specified in relation to the impeller 33, but the inner diameter and the arrangement position of the outflow channel 51 can be set relatively freely.

In the present embodiment, the inflow path 49 is set to have a diameter of 0.5 mm in relation to the flow rate of the paint, and is arranged such that the paint flowing from the inflow path 49 is received in the rotation direction of the impeller 33. Is set. The diameter of the inflow channel 49 can be set to a value other than 0.5 mm in relation to the flow rate of the paint. The inflow channel 49 communicates with the housing recess 43 at a position slightly inward of the inner circumferential surface of the housing recess 43. As a result, the paint flowing in from the inflow path 49 hits one blade 73, and the blade 73 rotates and moves due to the energy of the paint, and the next blade 73 flows in. Until facing the road 49, the paint can be sufficiently applied to the front blade portion 73. The outflow channel 51 is formed larger in diameter than the inflow channel 49 in order to reduce the outflow resistance. The inflow path 49 and the outflow path 51 are formed with an inlet 53 and an outlet 55 which are formed by female threads. The tube 15 is screw-connected to the inlet 53, and the tube 13 is screw-connected to the outlet 55. The lid 39 is provided with a convex portion 57 having a circular cross section. A support hole 58 is provided at the center of the protrusion 57. Female thread 5 9 Is provided. The female screw portion 59 is for screwing and supporting the proximity sensor 35.

The cover 39 has a square through hole 61 corresponding to the female screw 41 of the case 31. The lid 39 is fitted to the base 37, the projection 57 is fitted into the accommodation recess 43, and the blade accommodation space 63 is formed in the case 31. In this state, the ports 65 are individually inserted into the through holes 61 from the lid 39 side, and the bolts 65 are fastened to the female threads 41 to fasten the lid 39 to the base 37. Fixation has been made. An O-ring 67 is housed and held in the seal groove 47 so as to be in close contact with the lid 39 side, thereby sealing the blade housing space 63.

The impeller 33 is rotatably accommodated and supported in the blade accommodating space 63 of the case 31, and receives the paint flowing in from the inflow passage 49 in the rotating direction at the blade 73, and receives the paint. It rotates according to the flow rate.

The impeller 33 is made of a light metal such as aluminum and has high chemical resistance, low specific gravity and low moment of inertia. The impeller 33 can be formed of another material as long as it has similar characteristics. For example, the impeller 33 can be formed of a fluororesin such as Teflon (registered trademark).

The impeller 33 will be described with reference to FIGS. In the present embodiment, the impeller 33 is formed to have a diameter of about 20 mm and a thickness of about lmm in relation to the flow rate of the paint. However, the impeller 33 may have other sizes.

The impeller 33 has a plurality of blade portions 73 connected to the outer periphery of the disk portion 71. In the present embodiment, the blade portion 73 is formed in a saw blade shape and has directionality in the rotation direction. However, the blade portion 73 can be formed in a symmetrical shape in the rotation direction.

A fitting hole 75 is provided at the center of the disc portion 71. Mating hole 7 5 Is such that it is rotatably supported on the support shaft 69 without backlash. The impeller 33 is provided with a detection target portion 77, which constitutes a rotation speed detecting means together with the proximity sensor 35, by changing the surface configuration of the disk portion 71. Specifically, the surface morphology is changed by processing a concave portion 79 in the disk portion 71. The concave portions 79 are provided evenly at equal intervals in the rotation direction. In the present embodiment, the concave portions 79 are provided at four positions in a 90 ° arrangement. The space 81 between the recesses 79 is relatively convex with respect to the recess 79, and the recess 79 and the space 81 constitute the detection target portion 77.

It should be noted that the detection target portion 77 can also be provided by penetrating holes at regular intervals in the rotation direction in the disk portion 71 to change the surface form. In addition, it is also conceivable that the surface morphology is changed by providing protrusions on the surface of the disk portion 71 at regular intervals in the rotation direction. When a protrusion is formed on the disk portion 71, the protrusion can be used as a reinforcing rib, and the entire disk portion 71 can be further thinned. When the impeller 33 is formed of a fluororesin, for example, an aluminum surface is provided on the disk portion 71 at equal intervals in the rotational direction to change the surface form of the disk portion 71, and the detection by the proximity sensor 35 is performed. Will be done. When an aluminum surface is provided, an aluminum foil is attached to the surface of the disk portion 71 made of fluororesin, or a concave portion is formed on the surface of the disk portion 71, and the aluminum plate is accommodated in the concave portion. It can be considered that the surface of the disk part 71 is formed to be flush with the disk part 71, and a rod-shaped aluminum material is fixed to the disk part 71 at a constant interval in the rotation direction.

The impeller 33 is rotatably supported by a support shaft 69. In this embodiment, the support shaft 69 is formed of a fluororesin such as Teflon (registered trademark), and is fitted and fixed to the support holes 45, 58. In this state, a small gap of about 0.25 mm allowing relative rotation is formed between the blade portion 73 and the inner peripheral surface of the housing recess 43. A slight gap of about 0.5 mm is also formed between the surface of the disk portion 71 of the impeller 33 and the housing recess 43. Other sizes of these gaps can be selected. Although the impeller 33 rotates and slides with respect to the support shaft 69, the frictional resistance of the impeller 33 to the support shaft 69 is reduced because the support shaft 69 is formed of fluororesin. be able to. Further, since the support shaft 69 is formed of a fluororesin, the chemical resistance to thinner and the like is improved. The material of the support shaft 69 is not particularly limited as long as it has chemical resistance and a low coefficient of friction. For example, jewelry such as sapphires and the like can be used.

When the weight limitation of the impeller 33 is relaxed, the support shaft 69 is fixed to the impeller 33, and the support shaft 69 is rotatably supported in the support holes 45, 58. It can also be configured. Conversely, the support shaft 69 may be omitted, and the outer periphery of the impeller 33 may be guided to rotate by the inner peripheral surface of the housing recess 43. In this case, the number of parts is further reduced, and assembly and parts management become easier.

On both sides of the impeller 33, washers 85, 87 are provided. The washers 85 and 87 are made of, for example, a fluororesin, and have high chemical resistance and a low friction coefficient to reduce the frictional resistance to the impeller 33. In the present embodiment, the washers 85, 87 are press-fitted to the support shaft 69, and position the impeller 33 in the direction along the axis of the support shaft 69. In this positioning state, the impeller 33 is rotating relative to the washers 85, 87. Note that the washers 85 and 87 can be configured to be rotatable relative to both the impeller 33 and the support shaft 69.

The proximity sensor 35 is screwed and fixed to the female screw portion 59 of the case 31. The tip of the proximity sensor 35 projects into the blade accommodating section 63, for example, by about 0.6 mm. For example, a gap of about 0.3 mm is formed between the tip of the proximity sensor 35 and the disk portion 71 of the impeller 33, and the proximity sensor 35 causes the detection target portion 77 to be in a non-contact state. It can be detected. The protrusion amount of the proximity sensor 35 and the gap with respect to the disk portion 71 are set to other sizes. You can also. The proximity sensor 35 detects the gap 81 by the rotation of the impeller 33, becomes non-detected in the recess 79, and outputs a digital signal by repeating this detection and non-detection. .

Therefore, the rotation speed of the impeller 33 is counted by the controller of the flow meter 9 based on the output of the proximity sensor 35. The flow rate is calculated based on the counted number of rotations, and is digitally displayed on the display unit 27. That is, the flow rate is measured based on the rotation speed of the impeller 33.

Next, the operation will be described.

When the pump 5 is driven, the paint is supplied as a fluid from the paint tank 7 to the spray gun 3 through the pipe 17, the pump 5, the tube 15, the flow meter 9, and the tube 13. In the spray gun 3, for example, the spray amount is adjusted by adjusting the adjustment dial 11, so that the spray amount can be made uniform between the spray guns 3 and uniform application can be performed.

That is, when the flow path length from one pump 5 to each spray gun 3 is different, the flow rate reaching each spray gun 3 from pump 5 is small but may be different. . In order to perform uniform application evenly with each spray gun 3, adjust the adjustment dial 11 for each spray gun 3 even if the amount of paint supplied from the pump 5 to the spray gun 3 is slightly different. Therefore, it is necessary to make the spray amount between the spray guns 3 uniform.

Since the flow path length between each of the spray guns 3 and each of the flow meters 9 is set to be uniform, it is necessary to display the flow meter 9 in order to ensure a uniform injection amount between the spray guns 3. Adjust the adjustment dial 1 1 while looking at section 27. Thereby, the spray amount from each spray gun 3 can be finely adjusted, and the spray amount can be made uniform for each spray gun 3 so that the target object can be uniformly applied. In the flowmeter main body 29 in the flowmeter 9, the paint flows from the inlet 53 in FIG. 2 and further flows into the blade accommodating space 63 from the inflow passage 49. Inflow The paint is received by the blade portion 73 of the impeller 33. The blade portion 73 receives a driving force in the same direction as the direction of the kinetic energy of the flow of the paint, so that energy can be efficiently transmitted from the paint to the blade portion 73. By this driving force, the impeller 33 rotates around the support shaft 69 according to the flow rate of the paint.

The paint that has driven the blades 73 travels straight and flows out of the outflow channel 51, and flows from the outlet 55 to the tube 13. The paint is supplied from the tube 13 to the spray gun 3 as described above.

The rotation of the impeller 33 is detected by a proximity sensor 35. The proximity sensor 35 repeats non-detection and detection by the concave portion 79 and the intermediary portion 81, and outputs a digital signal. The controller of the flow meter 9 counts the digit signal and calculates the rotation speed of the impeller 33, and calculates the flow rate of the paint based on the rotation speed. The calculated flow rate is digitally displayed on the display unit 27 of the flow meter 9 as a measured value.

Therefore, the operator can adjust the adjustment dial 11 while looking at the display section 27, and can make the spray amount of each spray gun 3 uniform.

FIG. 7 shows a measurement result obtained by the flow meter 9 according to the embodiment of the present invention. As the fluid to be measured, a mixed solution of paint (30%), a solvent such as a thinner of about 70%, and tap water were used. The water pressure of the tap water and the liquid pressure of the mixed solution are both 0.15 MPa. The value of 0.15MPa was assumed for actual painting. Of course, other pressure values can be used as the actual pressure of the mixture depending on the conditions. In Fig. 7, the number of pulses is plotted on the vertical axis, and the flow rate is plotted on the horizontal axis. In FIG. 7, the symbol 〇 indicates the result of tap water W, and the symbol ▲ indicates the result of paint (the mixed liquid) P.

From this experimental result, it was confirmed that even in the case of the paint P, the impeller 33 rotated well, and the proximity sensor 35 output a high pulse. Regarding the measurement accuracy, it can be said that the dispersion is small compared to the approximate curve. That is, the minute flow rate of the paint P could be reliably measured. The measurement flow rate is According to the specification, it was possible from 20 m 1 / min.

Further, comparing the paint P and the tap water W, it can be seen that the rotation of the impeller 3 is lower in the case of the paint P than in the case of the tap water W even at the same flow rate. As a result, it was found that the rotation of the impeller 33 was different depending on the density, specific gravity, and viscosity of the measurement fluid. Therefore, by performing calibration using the fluid to be used in advance, the flow rate can be measured from the number of pulses.

As described above, the present embodiment has the following various effects. The detection target portion 77 is formed by changing the surface morphology by processing the concave portion 79 on the disk portion 71, and it is not necessary to embed the magnet in the impeller 33 as in the conventional case. 33 The weight of 3 can be reduced to reduce the moment of inertia. Further, since the magnet is not embedded in the impeller 33, the weight of the impeller 33 can be easily balanced, and the rotational imbalance can be suppressed. Further, even if the number of detection target portions 77 is increased to improve the measurement accuracy, only the concave portion 79 is processed, so that the weight increase of the impeller 33 can be reliably suppressed and the increase in the moment of inertia can be suppressed.

By reducing the moment of inertia, suppressing the increase in weight, and suppressing the rotational imbalance, the minute flow rate of highly viscous paint can be measured without difficulty.

Further, in the present embodiment, the impeller 33 is rotatable relative to the support shaft 69 and the washers 85, 87, so that the moment of inertia of the impeller 33 can be minimized. The flow rate can be measured easily and accurately.

Since the inflow channel 49 and the outflow channel 51 are linearly arranged along the tangential direction to the rotating circle of the impeller 33, the kinetic energy of the paint flowing from the inflow channel 49 is reduced. The blades 73 can receive the waste as it is without waste, and the outflow channel 51 can suppress the outflow resistance and discharge smoothly, and even the paint with a small flow rate can measure the flow rate accurately and effortlessly. Can The paint flowing in from the inflow channel 49 hits one blade portion 73, drives the blade portion 73, and moves the next blade portion 73 corresponding to the inflow channel 49 by the movement of the blade portion 73. In the meantime, the paint flowing from the inflow passage 49 can be sufficiently applied to the front blade portion 73, and the kinetic energy of the paint can be surely converted as the rotation of the impeller 33, so that the minute Even with paint with a flow rate, flow measurement can be performed reasonably accurately.

Even if the fluid is ignitable like paint, the paint does not come into contact with the heat-generating portion or spark because the electric motor is not used, so that ignition can be suppressed reliably.

In the coating apparatus 1, it is necessary to change the color of the paint according to the object to be coated. There are various paint colors, but metallic powders may be mixed with metallic colors. In such a case, when the rotation of the impeller 33 is detected by a magnetic field, the change in the magnetic field is affected by the metal powder, and the flow rate cannot be measured. In the case where the rotation of the impeller 33 is detected by light, if the fluid is a paint, the light does not pass and the flow rate cannot be detected.

On the other hand, by detecting the detection target portion 77 using the proximity sensor 35, it is possible to accurately measure the flow rate of any fluid such as paint containing metal powder as well as ordinary paint.

When the color of the paint is changed, the paint from the fuel tank 7 to the spray gun 3 is entirely washed with a thinner. That is, a thinner is accommodated in the fuel tank 7 and the pump 5 is driven to connect the thinner in the fuel tank 7 to the pipe 17, the pump 5, the tube 15, the flow meter 9, the tube 13, and the spray gun 3. The paint used previously is washed by passing it and ejecting it from the spray gun 3. In this case, in the flowmeter main body 29, the thinner reaches the inside of the blade accommodating space 63 by the rotation of the impeller 33, so that each part can be washed. After the cleaning is completed, the paint of another color is stored in the fuel tank 7, and the pump 5 is rotated again to spray the paint of another color on the object to be painted in the same manner as described above.

Even when using a thinner for the cleaning, the impeller 33, the washers 85, 87, the support shaft 69, and the case 31 have excellent chemical resistance as described above. It can fully withstand washing. 8 and 9 show another embodiment of the present invention. FIG. 8 is a cross-sectional view as viewed from above, and FIG. 9 is a cross-sectional view taken along the line SB-SB in FIG. Also in the present embodiment, the basic configuration is almost the same as the above embodiment, and the corresponding components are denoted by the same reference numerals.

In the present embodiment, the inflow channel 49 of the paint as a fluid is disposed to face the blade portion 73, while the outflow channel 51A is disposed to face the rotation center of the disk portion 71. It is. For this reason, in this embodiment, the support shaft 69 A that rotatably supports the impeller 33 is cantilevered on the base 37 A side of the case 31 A. Note that, in the figure, the left and right arrangement of the base 37A and the lid 39A of the case 31A is opposite to that of the above embodiment. However, this arrangement is not particularly limited, and may be the same as in the above embodiment.

An outflow channel 51A is provided at the center of the lid 31A side of the case 31A. The outflow channel 51A faces the end of the support shaft 69A, and has a larger diameter than the support shaft 69A.

The proximity sensor 35 is screwed and fixed to the base portion 37A side. The tube 15 is screw-connected to the inlet 53, and the tube 13 is screw-connected to the outlet 55A.

Although not shown, the base portion 37A and the lid portion 39A are connected to each other by squares using a porto as in the above embodiment.

Also in the present embodiment, by the proximity sensor 35 and the detection target unit 77, The rotation speed of the impeller 33 is detected, and flow measurement can be performed based on the rotation speed of the impeller 33.

On the other hand, the rotation of the impeller 33 may generate bubbles in the blade housing space 63. The foam tends to gather toward the rotation center of the impeller 33 when the impeller 33 rotates due to a difference in specific gravity from the paint. If the bubbles remain in the blade accommodating space 63, the impeller 33 receives rotational resistance due to the surface tension or the like, which may affect the flow rate measurement of the minute flow rate.

According to the experiment of the present inventor, when the flow rate was large, the influence of the bubbles was not so significant, but when the flow rate was reduced, the influence of the bubbles accounted for a relatively large ratio, and the rotational resistance was increased to adversely affect the flow rate measurement Came out.

In the embodiment of the present invention, as described above, the outflow path 51A is disposed opposite to the rotation center of the impeller 33, so that the bubbles collected on the rotation center side of the impeller 33 flow out together with the paint. The bubbles are discharged from the passage 51A, and the bubbles can be effectively discharged from the blade accommodating space 63.

Therefore, the remaining of the foam in the blade accommodating space 63 is suppressed, and the rotational resistance due to the foam can be suppressed or removed, and the flow rate of the minute flow rate can be measured more accurately.

Fig. 10 and Fig. 11 show a flowmeter body 29B according to still another embodiment, Fig. 10 is a cross-sectional view as viewed from a plane, Fig. 11 is the SC of Fig. 10. -SC is a sectional view taken in the direction of the arrow. Note that, also in this embodiment, the basic configuration is almost the same as the configuration of the embodiment in FIGS. 8 and 9, and the corresponding components are denoted by the same reference numerals.

In the present embodiment, for example, a pair of outflow paths 51B are provided, and the outflow paths 51B are opposed to the rotation center of the impeller 33. The support shaft 69B is also supported by a support hole 58B provided in the lid 39B of the case 31B, and is supported at both ends. The outflow passages 51B are symmetrically arranged so as to sandwich the support shaft 69B. The number of outflow channels 51B is not limited, and will increase further. The additional impeller 33 can be arranged in a circular shape around the rotation center of the additional impeller 33. In addition, the outflow channel 51B can be arranged in a single arrangement.

Also in the present embodiment, the bubbles collected at the center of the impeller 33 can be discharged from the outflow passage 51B together with the paint, and the rotational resistance due to the bubbles is suppressed, so that the flow rate measurement of the minute flow rate can be accurately performed. Can be performed.

Further, in the present embodiment, the support shaft 69 B is supported at both ends, so that the impeller 33 can be more reliably supported.

The flow meter of the present invention can be applied to all kinds of measurement, such as fuel cell fuel flow measurement and automobile fuel flow measurement, irrespective of paint flow measurement. Industrial applicability

As described above, the flow meter according to the present invention is designed to spray paint from a spray gun through a tube when spraying paint from a spray gun to coat a mobile phone housing, a cosmetic container, or a toy with various colors. Suitable for measuring the flow rate of paint being pumped into the gun.

Claims

The scope of the claims

1. A case provided with a fluid inflow path and a fluid outflow path, and a blade provided on the outer periphery of the disk part, rotatably housed and supported in the case and receiving the fluid flowing from the inflow path in the rotation direction by the blade. An impeller that rotates in accordance with the flow rate, and a rotation speed detecting unit that detects a rotation speed of the impeller, wherein the flow meter performs flow measurement based on the rotation speed of the impeller,

The rotation speed detecting means includes: a detection target portion provided by a change in the surface form of the disk portion; and a detection tool attached to the case and capable of detecting the detection target portion in a non-contact manner. And flow meter.

2. The flow meter according to claim 1, wherein

The flowmeter, wherein the detection target portion is provided by processing a concave portion or a hole portion in the disk portion.

3. The flowmeter according to claim 1, wherein the inflow path of the fluid is disposed to face the blade section, and the outflow path is a center of rotation of the disk section. A flow meter characterized by being arranged opposite to a part.

4. The flowmeter according to any one of claims 1 to 3, wherein the inflow path and the outflow path are connected to a supply path that supplies paint to a spray gun for painting, A flowmeter, comprising: display means for displaying a flow rate based on the rotation speed.