TW202417099A - Method of controlling dust collector in blasting apparatus and blasting apparatus - Google Patents

Abstract

To maintain air volume of a dust collector 30 provided in a blasting apparatus 1 constant with relatively simple and secure method. A differential pressure ΔP (differential pressure ΔP ₁between the pressure in the space 38 and the atmospheric pressure) in a predetermined position of a secondary side flow path 36 of a dust collecting filter 33 of the dust collector 30 is detected; and air volume control of controlling a rotation speed of a fan motor 312 provided in an air exhaust device 31 of the dust collector 30 and a fan 311 driven by the fan motor 312 by PID control with an inverter 61 is performed so as to bring a volume of passing air Q of the dust collector 30 grasped based on the detected differential pressure ΔP close to a preset target air volume Q ₀.

Description

Spray device and dust collector control method in spray device

The present invention relates to a dust collector control method in a blasting device and a blasting device for executing the dust collector control method, wherein the blasting device is used in blasting treatments such as sandblasting, shot blasting or shot peening, which is a treatment method of dry blasting a blasting material formed of a granular material such as metal, mineral, ceramic, glass, resin or plant seed shell onto a workpiece (in this specification, these are collectively referred to as "blasting treatment").

Note that in this specification, "blasting processing" of the blasting material may include various known methods that can accelerate the blasting material and spray it onto the workpiece in a dry manner, such as: blasting (spraying) of the material carried on the jet stream of a compressed gas such as compressed air; blasting using centrifugal force; and blasting by impact, etc.

FIG. 9 shows a configuration example of an air-type spraying device that sprays a spray material to a workpiece together with a spray flow of compressed air.

The spraying device 1 shown in Figure 9 includes a chassis 10, and a nozzle 12 for spraying a spraying material together with compressed air is provided in a working space 11 set in the chassis 10, and the spraying nozzle 12 is configured to perform a spraying process by spraying the spraying material onto a workpiece (not shown) in the working space 11 of the chassis 10.

The bottom 10a of the above-mentioned chassis 10 is formed in a hopper shape and is configured as follows: the spraying material sprayed in the working space 11 can be collected in the bottom 10a of the chassis 10 together with the crushed spraying material generated when the workpiece is scraped due to the collision of the spraying material with the workpiece and dust such as cutting powder.

The bottom 10 a of the housing 10 is connected to a classifier 20 including a wind classifier such as a cyclone through a collection duct 13 , and the classifier 20 is connected to a dust collector 30 including an exhaust device 31 through an exhaust duct 21 .

Therefore, by operating the exhaust device 31 arranged in the dust collector 30 to exhaust the interior of the classifier 20, the spray material collected together with the dust in the bottom 10a of the chassis 10 is introduced into the classifier 20 through the collecting pipe 13, and the reusable spray material after being sorted in the classifier 20 is collected in the spray material tank 22 connected to the bottom of the classifier 20.

On the other hand, the dust separated from the reusable spray material is sucked into the dust collector 30 through the exhaust pipe 21 together with the air in the classifier 20, and after the dust is removed by the dust filter 33 provided in the dust collector 30, the clean air is discharged to the outside of the spray device through the exhaust port 313c.

The spraying material collected in the spraying material tank 22 in this way is supplied again to the spraying nozzle 12 provided in the working space 11 of the chassis 10 through the spraying material hose 23, and is sprayed from the spraying nozzle 12 to a workpiece (not shown), whereby the spraying material can be used cyclically.

Regarding the dust collector 30 provided in the spray device 1 configured as described above, since a dust filter 33 is provided in the air flow path formed inside the dust collector, when dust adheres to the dust filter 33 and becomes clogged, the volume of air flowing through the dust collector 30 is reduced, and the force (suction force) used to draw air from the classifier 20 is reduced.

Therefore, when the suction force of the dust collector 30 decreases, the air volume flowing through the classifier 20 composed of a wind classifier such as a cyclone separator will decrease (the wind speed will decrease), so the classification performance of the classifier 20 will be reduced, and the amount of dust collected in the spray material tank 22 together with the spray material will increase.

When the amount of foreign matter such as dust mixed into the blasting material collected as the reusable material in this way increases, the accuracy of the blasting process performed using the collected blasting material decreases, and the blasting process cannot be continuously performed with constant quality.

Note that in order to cope with the clogging of the dust filter 33, the dust collector 30 is also provided with a manual rocker 35, and the dust collector 30 is configured as follows: when the suction force of the dust collector 30 is reduced due to the clogging of the dust filter 33, the rocker 35 can be operated to remove the dust collected by the dust filter 33 to restore the air volume (suction force) flowing through the dust collector 30.

However, even when the suction of the dust collector 30 is restored by removing the dust collected by the dust filter 33 using the joystick 35, the change in the flow air volume (suction force) of the dust collector 30 is a sawtooth waveform change as shown in Figure 10. The reason is that: because the clogging of the dust filter 33 will further develop with the passage of time, the air volume flowing through the classifier 20 will decrease, and then it will be immediately restored by removing the dust attached to the dust filter 33 by operating the joystick 35.

As a result, in the process of restoring the flow air volume (suction force) by operating the joystick 35, there is no effect of stabilizing the flow air volume (suction force) of the dust collector 30, and correspondingly, there is no effect of stabilizing the classification performance of the classifier 20.

As described above, since the suction force of the dust collector 30 is reduced due to the blockage of the dust filter 33 arranged in the dust collector 30, etc., this leads to the reduction of the classification performance of the classifier 20 arranged in the spray device 1. Therefore, it is currently desired to provide a spray device including the following dust collector 30, which will not be affected by the blockage of the dust filter 33, etc. but can always suck air from the classifier 20 with a constant air volume.

Note that although Japanese Patent Application Publication No. H11-169634 (hereinafter, referred to as "Yoshida") is not an invention related to a dust collector of an ejector device, the Japanese Patent Application "Yoshida" once proposed that in a ceiling-mounted air conditioning device equipped with a high-efficiency particulate air filter (HEPA filter), in order to prevent changes in air volume due to clogging of the HEPA filter, the pressure on the primary side and the pressure on the secondary side of the HEPA filter are measured, and the pressure loss (pressure loss) relative to the initial state is obtained by calculation. The invention relates to a method for increasing the pressure loss increment ΔPt of a HEPA filter and increasing the torque of a fan motor disposed in the dust collector based on the obtained pressure loss increment ΔPt so as to increase the air volume flowing through the HEPA filter and compensate for the decrease in the air volume (Claim 1, Claim 2, paragraphs [0019] to [0020] and FIG. 1 of Yoshida).

In the air conditioning apparatus described by Yoshida and introduced above, the pressure loss caused by the HEPA filter is detected, and the decrease in air volume that occurs with the detected pressure loss increment ΔPt relative to the initial value of the pressure loss is compensated by increasing the fan motor torque, thereby maintaining the air volume flowing through the air conditioning apparatus constant even when the HEPA filter is clogged.

Therefore, when the fan motor 312 of the exhaust device 31 provided in the dust collector 30 of the spray device 1 shown in reference figure 9 is controlled so as to increase the torque according to the pressure loss increment ΔPt obtained by measuring the pressure on the primary side and the secondary side of the dust filter 33 according to Yoshida, the air volume flowing through the dust filter 33 can be maintained constant, thereby, the air volume flowing through the classifier 20 can also be maintained constant, and the classification performance of the classifier 20 can be stabilized.

However, when the dust collector 30 provided in the spraying device 1 is controlled by the method described in Yoshida, the following problem may occur.

The flow rate Q (m ³ /s) of a fluid can be expressed as the product of the area A (m ² ) of the flow path through which the fluid flows and the flow velocity V (m/s) of the fluid (Q = AV).

Here, the velocity V (m/s) of the fluid is calculated based on Bernoulli's theorem.

V = (2q/ρ) ^1/2 (Equation 1)

Where q represents the dynamic pressure (Pa), and ρ represents the fluid density (kg/cm ³ ).

Therefore, the flow rate Q (m ³ /s (cubic meters/second)) of the fluid is expressed as follows:

Q = AV = A (2q/ρ) ^1/2 (Equation 2)

According to Equation 2, when the area A (m ² ) of the flow path through which the fluid flows is constant and the density of the fluid is constant, the change in the flow rate Q (m ³ /s) of the fluid can be obtained based on the change in the dynamic pressure q (Pa).

However, in the case of attempting to measure the air volume of air flowing through the dust filter 33 disposed in the dust collector 30 using the method described by Yoshida, even when the pressure difference (dynamic pressure) between the primary and secondary sides of the dust filter 33 and the density of the fluid (air) are known, the air volume cannot be obtained unless the flow path area A (m ² ) (i.e., the total area of the openings of the filter) is known.

The total area of the openings of the dust filter 33 (flow path area A) has a unique initial value depending on various conditions such as the grade, manufacturer and size of the filter to be used, and the total area changes with the passage of time due to clogging of the dust filter 33, so it is difficult to measure the total area.

Therefore, in order to obtain the necessary increase ΔFu of air volume (the decrease of air volume with the increase of pressure loss) by calculation processing based on the pressure loss increase ΔPt which increases with time according to Yoshida's method, so as to obtain the increase of fan motor torque (the increase of air volume increase Δfu can be obtained by increasing the fan motor torque), it is necessary to conduct experiments in advance. Thus, for each combination of the dust collector 30 and the dust filter 33, the pressure loss value and the flow air volume are measured as initial values, and how the pressure loss changes as the air volume decreases when the dust is collected and the air volume is reduced is measured, and an expression for the relationship between the pressure loss increment ΔPt and the corresponding air volume increment Δfu is obtained (Yoshida's paragraph [0019]).

Furthermore, in order to obtain the above-mentioned relational expression, in the measurement, the dust filter 33 must be actually clogged by operating the spraying device so as to collect dust and the like, and thus the measurement takes a long time.

In addition, because the air volume flowing through the dust filter 33 is increased by controlling the torque of the fan motor according to Yoshida's method, it is necessary to obtain the relationship between the total air volume Fut and the fan motor torque by experimentally taking into account the necessary air volume increment ΔF (Yoshida's paragraph [0020]), and therefore, not only a lot of labor is required to prepare for the control, but also the calculation processing required to be performed during the control is increased, which leads to complex control.

Furthermore, according to the method described by Yoshida, even when the same dust collector 30 is used, when the initial values of the pressure loss and the flow air volume and the relationship between the pressure loss increment ΔPt and the necessary air volume increment ΔF are changed (for example, when the dust filter 33 mounted to the dust collector 30 is replaced with a dust filter of a different grade or a different manufacturer), each of these data must be experimentally reobtained each time such a replacement of the dust filter 33 occurs, and the above-mentioned relationship expression and control procedure must be recombined.

In addition, the control performed according to the method described by Yoshida can compensate for the reduction in flow air volume due to clogging of the dust filter 33, but cannot cope with the reduction in air volume due to other reasons (for example, the reduction in flow air volume due to the narrowing of the flow path caused by the spraying material or dust adhering to the inner wall of the collection duct or the exhaust duct, etc.).

Therefore, the present invention is made in view of the above-mentioned shortcomings in the prior art, and an object of the present invention is to provide a dust collector control method in an ejector device and an ejector device for executing the dust collector control method, wherein the ejector device can not only maintain the classification performance of the classifier by maintaining the flow air volume of the dust collector (i.e., the flow air volume of the classifier) at a constant level by utilizing a relatively simple method, but also can maintain the classification performance of the classifier even when the pressure loss of the dust filter and the initial value of the flow air volume and the relationship between the pressure loss and the flow air volume change ( For example, when the dust filter is replaced with a different high-quality dust filter), the flow air volume can be maintained at a constant level without resetting the relational expression or replacing the control program. In addition, not only can the air volume reduction due to clogging of the dust filter be prevented, but also the overall reduction in the flow air volume caused by the narrowing of the flow path in the dust filter and the main stage side of the dust filter due to reasons such as the adhesion of sprayed materials and dust to the inner wall of the collection duct or the discharge duct can be prevented.

The means for solving the above-mentioned problems are described below with reference to the reference signs used in the detailed description of the preferred embodiment. These reference signs are intended to clarify the corresponding relationship between the records in the claim and the records in the detailed description of the preferred embodiment, and it goes without saying that these reference signs should not be used to restrictively interpret the technical scope of the present invention.

In order to achieve the above-mentioned purpose, according to the present invention, a control method of a dust collector 30 in a spraying device 1 is provided, wherein the spraying device 1 is provided with: a chassis 10 containing a working space 11; a classifier 20, which includes a wind classifier, and the wind classifier introduces and classifies the spraying material sprayed and collected together with the dust in the chassis 10; a spraying material tank 22, which stores the reusable spraying material classified by the classifier 20; and a dust collector 30, which includes a fan 311, and the fan 311 sucks and discharges the air from the classifier 20. The spraying device 1 generates airflow in the classifier 20 through the suction of the dust collector 30, and uses the airflow to collect the reusable spraying material into the spraying material tank 22 through wind sorting. The control method includes the following steps:

Detecting a differential pressure ΔP (ΔP ₁ or ΔP ₂ ) in a secondary-side flow path 36 , which is a flow path disposed at the secondary-side of the dust filter 33 of the dust collector 30 ; and performing air volume control for controlling the rotation speed of the fan 311 , so that the flow air volume Q of the dust collector 30 controlled based on the detected differential pressure ΔP (ΔP ₁ or ΔP ₂ ) is close to a preset target air volume Q ₀ .

The control method of the dust collector 30 may be configured to include the following steps:

The fan 311 is disposed in the secondary-stage side flow path 36, and the secondary-stage side flow path 36 is opened to the atmosphere at the secondary-stage side of the fan 311;

Detecting a pressure difference ΔP ₁ between the pressure in the space 38 between the dust filter 33 and the fan 311 in the secondary-side flow path 36 and the atmospheric pressure as the pressure difference ΔP in the secondary-side flow path 36;

According to the detected pressure difference _ΔP1 between the pressure in the space 38 and the atmospheric pressure and the rotation speed of the fan 311 when the pressure difference _ΔP1 is detected (in this example, the inverter output Inv corresponding to the rotation speed), the flow air volume Q of the dust collector 30 is calculated based on a preset relationship expression [e.g., Q = f( _ΔP1 , Inv)]; and

The air volume control for controlling the rotation speed of the fan 311 is performed so that the calculated flow air volume Q approaches the target air volume Q ₀ .

Alternatively to the above configuration, the control method may be configured to include the following steps:

detecting a pressure difference ΔP ₂ before and after an orifice 41 disposed in the secondary-stage-side flow path 36 as a pressure difference ΔP in the secondary-stage-side flow path 36; and

The air volume control for controlling the rotation speed of the fan 311 is performed so that the detected pressure difference ΔP ₂ before and after the orifice 41 is close to the preset target pressure difference ΔP ₀ , and the preset target pressure difference is the pressure difference before and after the orifice 41 corresponding to the target air volume Q ₀ , thereby making the flow air volume Q close to the target air volume Q ₀ .

Alternatively, the control method may be configured to include the following steps:

Detecting a pressure difference ΔP ₂ before and after an orifice 41 disposed in the secondary-stage-side flow path 36 as the pressure difference ΔP in the secondary-stage-side flow path 36;

Calculating the flow volume Q of the dust collector 30 based on the detected pressure difference ΔP ₂ before and after the orifice 41 and a preset relationship expression [e.g., Q = f(ΔP ₂ )]; and

The air volume control for controlling the rotation speed of the fan 311 is performed so that the calculated flow air volume Q approaches the target air volume Q ₀ .

In any of the above configurations, the following steps are preferably included:

Setting the flow air volume Q of the dust collector 30, which will cause the dust filter 33 to have a coarse mesh in the initial use stage, to the limit air volume Qmax; and

The rotation speed of the fan 311 is controlled (including stopping) so that the flow air volume Q is less than the maximum air volume Qmax.

In addition, in the configuration for detecting the pressure difference _ΔP1 between the pressure in the space 38 between the dust filter 33 and the fan 311 in the secondary-side flow path 36 and the atmospheric pressure (see FIGS. 1 and 2 ), the following steps are preferably included:

Pre-measuring the pressure difference before and after the dust filter 33 which will cause the dust filter 33 to be damaged as a pressure resistance limit pressure difference ΔPfmax; and

The rotation speed of the fan 311 is controlled (including stopping) so that the measured value of the pressure difference _ΔP1 between the pressure in the space 38 between the dust filter 33 and the fan 311 in the secondary-side flow path 36 and the atmospheric pressure is less than the value set as the withstand pressure limit pressure difference ΔPfmax.

In addition, the control method may be configured to: when the rotation speed of the fan 311 reaches a predetermined upper speed limit, the fan 311 is stopped urgently.

In addition, the spraying device 1 of the present invention is provided with: a cabinet 10 containing a working space 11; a classifier 20, which includes a wind classifier, and the wind classifier introduces and classifies the spraying material sprayed and collected together with the dust in the cabinet 10; a spraying material tank 22, which stores the reusable spraying material after being classified by the classifier 20; and a dust collector 30, which includes a fan 311, and the fan 311 sucks and discharges the air from the classifier 20. The spraying device 1 collects the reusable spraying material into the spraying material tank 22 through wind classification using the airflow generated in the classifier 20 due to the suction of the dust collector 30. The spraying device 1 includes:

a pressure detection mechanism 50 that detects a pressure difference ΔP ( _ΔP1 or _ΔP2 ) in a secondary-side flow path 36, the secondary-side flow path 36 being a flow path provided at the secondary-side of the dust filter 33 of the dust collector 30; and

The control device 60 performs air volume control for controlling the rotation speed of the fan 311 so that the flow air volume Q of the dust collector 30 controlled based on the pressure difference ΔP (ΔP ₁ or ΔP ₂ ) detected by the pressure detection mechanism 50 approaches a preset target air volume Q ₀ .

The spraying device 1 having the above configuration may be configured as follows:

The fan 311 is disposed in the secondary-stage flow path 36, and the secondary-stage flow path 36 is open to the atmosphere at the secondary-stage side of the fan 311;

A pressure sensor ₅₁ for detecting a pressure difference ΔP1 between the pressure in the space 38 between the dust filter 33 and the fan 311 in the secondary-side flow path 36 and the atmospheric pressure is provided as the pressure detection mechanism 50; and

The control device 60 calculates the flow air volume Q of the dust collector 30 based on the pressure difference _ΔP1 relative to the atmospheric pressure detected by the pressure sensor 51 and the rotation speed of the fan 311 when the pressure difference _ΔP1 is detected (in this example, the inverter output Inv corresponding to the rotation speed) based on a preset relationship expression [for example, Q = f( _ΔP1 , Inv)], and the control device 60 performs air volume control for controlling the rotation speed of the fan 311 so that the calculated flow air volume Q is close to the target air volume _Q0 .

Alternatively, the configuration may be such that the pressure detection mechanism 50 is a pressure difference sensor 52 for detecting the pressure difference _ΔP2 before and after the orifice 41 disposed in the secondary-side flow path 36; and

The control device 60 performs air volume control for controlling the rotation speed of the fan 311 so that the pressure difference _ΔP2 before and after the orifice 41 detected by the pressure difference sensor 52 is close to the preset target pressure difference _ΔP0 . The preset target pressure difference _ΔP0 is the pressure difference before and after the orifice 41 corresponding to the target air volume _Q0 . Thus, control is performed to make the flow air volume Q close to the target air volume _Q0 .

In addition, the configuration may be such that: the pressure detection mechanism 50 is a pressure difference sensor 52 for detecting the pressure difference _ΔP2 before and after the orifice 41 provided in the secondary-side flow path 36; and

The control device 60 calculates the flow air volume Q of the dust collector 30 according to the pressure difference ΔP ₂ before and after the orifice 41 detected by the pressure difference sensor 52 and based on a preset relationship expression [for example, Q = f(ΔP ₂ )], and the control device 60 performs air volume control for controlling the rotation speed of the fan 311 so that the calculated flow air volume Q is close to the target air volume Q ₀ .

Any of the above-mentioned spray devices 1 can be configured as follows: the control device 60 stores the flow air volume Q of the dust collector 30, which will cause the dust filter 33 to have a coarse mesh in the initial use stage, as the maximum air volume Qmax, and the control device 60 controls the rotation speed of the fan 311 (including stopping) so that the flow air volume Q is less than the maximum air volume Qmax.

In addition, in the configuration for detecting the pressure difference _ΔP1 between the pressure in the space 38 between the dust filter 33 and the fan 311 in the secondary side flow path 36 and the atmospheric pressure, the configuration can be as follows: the control device 60 stores the pressure difference before and after the dust filter 33 that will cause damage to the dust filter 33 as the withstand pressure limit pressure difference ΔPfmax, and the control device 60 controls the rotation speed of the fan 311 (including stopping) so that the pressure difference ΔP1 between the pressure in the space 38 between the dust filter 33 and the fan 311 in the secondary side flow path 36 and the atmospheric pressure is reduced to ΔPfmax. ₁ is less than the withstand voltage limit voltage difference ΔPfmax.

In addition, the control device 60 may be configured such that when the rotation speed of the fan 311 reaches a predetermined upper limit rotation speed, the control device 60 causes the fan 311 to stop in an emergency.

According to the configuration of the present invention as described above, by controlling the dust collector 30 of the spray device 1 using the control method of the present invention, evaluation can be performed as follows.

By detecting the pressure difference ΔP (ΔP ₁ or ΔP ₂ ) in the secondary-side flow path 36 which is the flow path at the secondary-side of the dust filter 33 of the dust collector 30 , and by performing air volume control for controlling the rotation speed of the fan 311 so that the flow air volume Q of the secondary-side flow path 36 controlled based on the pressure difference ΔP (ΔP ₁ or ΔP ₂ ) approaches the target air volume Q ₀ , the air volume flowing through the classifier 20 can be stabilized to a constant amount, and even when clogging occurs in the dust filter 33 of the dust collector 30 , the quality of the collected spray material can be maintained constant without changing the classification performance of the classifier 20 .

As a result, in the spraying device 1 in which the dust collector 30 is controlled by the control method of the present invention, the processing accuracy can be maintained constant even when the collected spraying material is circulated and used multiple times.

In addition, although the process of making the flow air volume Q controlled based on the pressure difference ΔP ( _ΔP1 or _ΔP2 ) in the secondary side flow path 36 close to the target air volume _Q0 is very simple and easy to control, even if the characteristics of the dust filter 33 are changed by changing the dust filter 33 to, for example, a dust filter with a coarse mesh or a dust filter with fine meshes of different levels, the air volume of the air flowing through the classifier 20 can be maintained constant without changing the control program or calculation expression, etc.

In a configuration in which the secondary-side flow path 36 is open to the atmosphere at the secondary-side of the fan 311, the secondary-side flow path 36 can be configured to detect the pressure difference _ΔP1 between the pressure in the space 38 between the dust filter 33 and the fan 311 in the secondary-side flow path 36 and the atmospheric pressure, and the rotation speed of the fan 311 when the pressure difference _ΔP1 is detected (in this example, the inverter output Inv corresponding to the rotation speed) and based on a preset simple relationship expression [for example, Q = f( _ΔP1 , Inv)] is calculated to obtain the flow volume Q of the secondary side flow path 36, and the flow volume in the classifier 20 can be easily maintained constant based on the pressure detected by the single pressure sensor 51 (the pressure difference ΔP ₁ relative to the atmospheric pressure).

In a configuration in which the flow air volume Q is controlled by detecting the pressure difference _ΔP2 before and after an orifice 41 set at a predetermined position in the secondary-stage side flow path 36, even when the configuration is not limited to a configuration in which the secondary-stage side flow path 36 is open to the atmosphere, but another device is further connected to the secondary-stage side flow path 36, control for making the flow air volume Q of the secondary-stage side flow path 36 approach the target air volume _Q0 can be performed without being affected by the increase in exhaust resistance caused by the connection of another device.

As a result, even when a HEPA filter or the like is further provided in the secondary-stage flow path 36 at the secondary-stage side of the orifice 41 to clean the exhaust air or the like, the flow volume Q can be maintained constant without being affected by changes in the exhaust resistance or the like that occur as the clogging of the HEPA filter progresses.

In addition, in the above-mentioned configuration in which the above-mentioned air volume control is performed in a manner of measuring the pressure difference _ΔP2 before and after the orifice 41 arranged in the secondary side flow path 36 so as to control the flow air volume Q, the air volume control for controlling the rotation speed of the fan 311 is performed only by directly utilizing the detected pressure difference _ΔP2 before and after the orifice 41 so as to make the pressure difference close to the set target pressure difference _ΔP0 , and the control for making the flow air volume Q close to the target air volume _Q0 can also be performed without having to perform a step of obtaining the flow air volume Q based on an arithmetic expression, etc.

In addition, the control method mentioned by Yoshida can only respond to the reduction in air volume caused by the blockage of the filter, but the dust collector controlled by any method of the present invention can not only respond to the reduction in flow air volume caused by the blockage of the dust filter 33, but also generally respond to the overall reduction in flow air volume Q caused by the increase in flow path resistance generated on the main stage side of the measurement position of the pressure difference ΔP ( _ΔP1 or _ΔP2 ), for example, the overall reduction in flow air volume Q caused by the narrowing of the flow path caused by the accumulation of sprayed materials or dust on the inner wall of the collection pipe 13 or the exhaust pipe 21.

Note that the dust filter 33 attached to the dust collector 30 is a bag filter generally called a “bag filter”, and has a structure that collects dust by introducing air to be purified into the bag filter 33 and causing the air to flow through the bag filter 33.

When the blockage develops to a certain extent, the dust filter 33 expands due to the introduction of air, and the air will always flow through the entire dust filter 33.

However, when air is introduced in a state where no clogging occurs in the initial use stage, the dust filter 33 is in a deflated state rather than being consistently inflated, and thus, air flows intensively only through the portion of the dust filter 33 located at the front in the air introduction direction.

As a result, if the flow air volume Q is excessively increased when the dust filter 33 is in the initial use stage, the mesh of the portion through which air flows intensively will be coarse compared to the mesh of other portions, and thus the function of the dust filter 33 may be impaired.

In contrast, by setting the flow air volume of the dust filter 30, which will cause the dust filter 33 to have a coarse mesh in the initial use stage, to the maximum air volume Qmax, and by controlling the speed of the fan 311 (including stopping) so that the detected value of the flow air volume Q is less than the value set to the maximum air volume Qmax, it is possible to properly prevent functional loss from occurring in the dust filter 33 in the initial use stage.

In addition, in the configuration for detecting the pressure difference _ΔP1 between the pressure in the space 38 between the dust filter 33 and the fan 311 in the secondary side flow path 36 and the atmospheric pressure, the pressure difference _ΔP1 between the pressure in the space 38 and the atmospheric pressure always has a value equal to or greater than the pressure difference before and after the dust filter 33.

Therefore, the pressure difference before and after the dust filter 33 that may cause damage to the dust filter 33 is measured in advance as the withstand pressure limit pressure difference ΔPfmax, and the speed of the fan 311 is controlled (including stopping) so that the measured value of the pressure difference _ΔP1 between the pressure in the space 38 and the atmospheric pressure is less than the value set as the withstand pressure limit pressure difference ΔPfmax. In this way, the dust filter 33 can be prevented from being blocked. In order to make the flow air volume Q close to the target air volume _Q0 , the speed of the fan 311 is increased until the dust filter 33 is damaged.

In any of the above-mentioned control methods for the dust collector 30, the rotation speed of the fan 311 is increased as the clogging of the dust filter 33 provided in the dust collector 30 progresses, but when the fan 311 reaches a predetermined upper speed limit, the fan 311 is stopped urgently. Thus, the fan motor 312 can be prevented from being damaged by being driven in excess of the rated value by appropriately setting the upper speed limit within a range equal to or lower than the rated speed of the fan motor 312, and, for example, the rotation speed of the fan motor 312 can be experimentally obtained in advance. The corresponding relationship between the change in the speed and the change in the pressure difference between the primary side and the secondary side of the dust filter 33 is established, and the upper limit speed is set so that the pressure difference falls within a range not exceeding the pressure difference set for the pressure resistance performance of the dust filter 33, preferably so that the pressure difference is a value lower than the pressure difference set for the pressure resistance performance by a predetermined margin, thereby preventing the pressure difference between the primary side and the secondary side of the dust filter 33 from increasing to exceed the pressure difference set for the pressure resistance performance of the dust filter 33, and preventing the dust filter 33 from being damaged.

Next, the embodiments of the present invention will be described with reference to the accompanying drawings.

[Overall configuration example of spray equipment]

The spraying device 1 to which the control method of the present invention is applicable is similar to the known spraying device 1 described with reference to FIG. 9 in that it comprises: a cabinet 10 containing a working space 11; a classifier 20, which comprises a wind classifier, which introduces and classifies the spraying material sprayed and collected together with the dust in the cabinet 10; a spraying material tank 22, which stores reusable spraying material classified by the classifier 20; and a dust collector 30, which comprises a fan 311, which sucks and discharges the air from the classifier 20.

Then, when the air is sucked and discharged from the classifier 20 by the rotation of the fan 311 provided in the dust collector 30, the spray material accumulated in the bottom 10a of the chassis 10 is introduced into the classifier 20 together with the dust through the collecting pipe 13. The configuration described below is also similar to the configuration of the known spraying device 1 described with reference to FIG9: the reusable spray material after being classified in the classifier 20 is collected in the spray material tank 22, the dust is collected in the dust collector 30 together with the air in the classifier 20 through the exhaust pipe 21, and the clean air after the dust is removed by the dust filter 33 in the dust collector 30 is discharged from the exhaust port (see 313c in FIG1) of the dust collector 30.

Now let's continue with the description. Referring to FIG. 9 , the spray device 1 has a configuration example of a "circulating" spray device 1, in which the spray material collected in the spray material tank 22 can be introduced into the spray nozzle 12 arranged in the chassis 10 through the spray material hose 23, but the spray device 1 to which the control method of the present invention is applicable does not necessarily need to have a configuration for recirculating the collected spray material to the spray nozzle 12, as long as the spray device can execute the process of collecting the spray material in the spray material tank 22.

[Overview of control of the present invention]

Unlike the known ejector device 1 mentioned above, the ejector device 1 of the present invention is configured as follows: a pressure detection mechanism 50 (51, 52) capable of detecting a pressure difference ΔP (ΔP ₁ or ΔP ₂ ) in the secondary-stage side flow path 36 is provided in the secondary-stage side flow path 36, and the secondary-stage side flow path 36 is an air flow path provided at the secondary-stage side of the dust filter 33 of the dust collector 30, and a change in the flow air volume Q of the dust collector 30 can be controlled based on the detected pressure difference ΔP (ΔP ₁ or ΔP ₂ ).

The spray device 1 of the present invention includes a control device 60, which performs air volume control for controlling the rotation speed of a fan 311 arranged in the dust collector 30, so that the flow air volume Q controlled based on the pressure difference ΔP ( _ΔP1 or ΔP2) detected by the pressure detection mechanism 50 (51, ₅₂ ) is close to the preset target air volume _Q0 , thereby, the flow rate of air flowing through the classifier 20 can be maintained at a constant amount, and the classification performance of the classifier 20 can be maintained unchanged.

In order to be able to achieve this control of the rotational speed of the fan 311 of the dust collector 30, in the dust collector 30 of the spray device of the present invention, the fan motor 312 is a three-phase AC (alternating current) motor, preferably a three-phase AC motor controlled by an inverter, and as shown in Figures 1, 4 and 6, the configuration of the above-mentioned control device 60 includes an inverter 61, which first converts AC (alternating current) from a power source (for example, a commercial power source) (not shown) into DC (direct current), and then converts the DC into AC of any selected frequency and outputs the AC, so that the frequency of the AC output to the fan motor 312 can be changed.

The inverter 61 is configured such that the output Inv (kW) of the inverter 61 increases as the output frequency (Hz) increases, and the output Inv (kW) of the inverter 61 decreases as the output frequency (Hz) decreases, using known methods such as V/f (output voltage amplitude/frequency) control technology. Therefore, by increasing the output Inv (kW) of the inverter 61, the rotation speed increases together with the power (W) of the fan motor 312, and by decreasing the output Inv (kW) of the inverter 61, the rotation speed decreases together with the power (W) of the fan motor 312.

Therefore, the PID control function of the inverter 61 can change the output Inv (kW) of the inverter 61 so that the flow air volume Q controlled based on the pressure difference ΔP (ΔP ₁ or ΔP ₂ ) in the secondary-side flow path 36 detected by the pressure detection mechanism 50 is close to the preset target air volume Q ₀ . As a result, the flow air volume Q flowing through the dust collector 30 can be consistent with the target air volume Q ₀ as quickly as possible.

[First Configuration Example of the Control Device of the Present Invention]

FIG. 1 shows a configuration example of a control device 60 in which the dust collector 30 to be controlled is a case where the exhaust port 313c thereof is open to the atmosphere.

As shown in FIG2 , as an example, in the dust collector 30 to be controlled in FIG1 , the filter housing 32 containing the dust filter 33 has an inlet 32a and an outlet 32b, the inlet 32a is connected to the exhaust pipe 21 communicating with the classifier 20, the outlet 32b is used to discharge the air flowing through the dust filter 33, and an exhaust device 31 including a fan 311 and a fan motor 312 is installed at the outlet 32b. The exhaust device 31 can suck the inside of the filter housing 32.

The exhaust device 31 includes: a fan housing 313 having a cylindrical duct 314 mounted to the outlet 32b of the filter housing 32; an inlet 313a communicating with the duct 314; a housing space 313b for housing the fan 311; and an exhaust outlet 313c open to the atmosphere.

Therefore, in the configuration of the dust collector 30 in FIG2 , the portion from the duct 314 of the exhaust device 31 to the exhaust port 313 c of the fan housing 313 constitutes a secondary-side flow path 36 provided at the secondary-side of the dust filter 33, and the fan 311 is arranged in the secondary-side flow path 36. The end (exhaust port 313 c) of the secondary-side flow path 36 is open to the atmosphere at the secondary-side of the fan 311.

In the configuration of FIG. 1 for controlling the dust collector 30, a pressure sensor 51 is provided as the pressure detection mechanism 50. The pressure sensor 51 is used to detect the pressure difference (absolute value of gauge pressure) ΔP1 between the pressure in the space ₃₈ between the dust filter 33 and the fan 311 (the space in the duct 314) and the atmospheric pressure. In addition, in the configuration of FIG. 1, an operation device 62 is also provided. The operation device 62 calculates the pressure difference ΔP1 detected by the pressure sensor 51 and the pressure difference _ΔP1 when the pressure difference ΔP1 is detected. The flow air volume Q is calculated using a predetermined relational expression from the rotation speed of the fan 311 at ₁ o'clock (the output Inv (kW) of the inverter 61 corresponding to the rotation speed of the fan 311).

The flow air volume Q as the calculation result of the operation device 62 is input to the inverter 61, causing the inverter 61 to perform the above-mentioned air volume control by PID control for changing the output Inv to the fan motor 312, thereby making the flow air volume Q approach the target air volume Q ₀ .

Therefore, in the configuration shown in FIG. 1 , the control device 60 for controlling the rotation speed of the fan 311 of the dust collector 30 is realized by the above-mentioned operation device 62 and the inverter 61 .

As an example, FIG3 shows the relationship between the pressure difference _ΔP1 between the pressure in the space 38 between the dust filter 33 and the fan 311 (the space in the duct 314) and the atmospheric pressure, the flow volume Q of the dust collector 30, and the power W of the fan motor 312 corresponding to the rotation speed of the fan 311. The flow volume Q of the dust collector 30 is a function of the pressure difference _ΔP1 between the pressure in the space 38 and the atmospheric pressure and the power W of the fan motor 312, and is represented by the relational expression Q = f( _ΔP1 , W).

Here, since the power W of the fan motor 312 is proportional to the inverter output Inv (kW) input to the fan motor 312, the flow volume Q of the secondary side flow path 36 has a relational expression Q = f(ΔP ₁ , Inv), which is a function of the pressure difference ΔP ₁ between the pressure in the space 38 and the atmospheric pressure and the inverter output Inv.

Therefore, as shown in FIG1 , by obtaining the relational expression Q = f(ΔP ₁ , Inv) by an experimental method and pre-storing the relational expression in the computing device 62 , the computing device 62 can calculate the flow volume Q based on the pressure difference ΔP ₁ between the pressure in the space 38 detected by the pressure sensor 51 and the atmospheric pressure and the inverter output Inv.

Then, the flow air volume Q obtained by the calculation of the operation device 62 is input to the inverter 61, and the inverter 61 changes the output Inv (kW) by known control techniques such as PID control so that the input flow air volume Q approaches the preset target air volume Q _0. With this configuration, the air volume flowing through the dust collector 30 can be maintained constant not only when clogging occurs in the dust filter 33, but also when the dust filter 33 is replaced by a dust filter of a different stage, and further when any flow path resistance on the main stage side of the dust filter 33 increases.

[Second Configuration Example of Control Device]

As described above, in the description made with reference to FIG. 1 , the configuration example in which the dust collector 30 to be controlled is the case in which the exhaust port 313 c is open to the atmosphere is described.

In this configuration, since the exhaust resistance (back pressure) of the air flowing through the secondary-stage side flow path 36 is constant and does not change under atmospheric pressure, the change in the flow volume Q flowing through the secondary-stage side flow path 36 can be obtained based on the surface pressure (pressure difference relative to atmospheric pressure) ΔP1 in the space 38 in the pipeline 314 detected by the general pressure sensor ₅₁ and the output Inv of the inverter 61 when the pressure difference ΔP1 _is detected.

However, as shown in FIGS. 4 and 5 , if an exhaust pipe 40 is further connected to the exhaust port 313 c of the exhaust device 31, and a subsequent device such as a HEPA filter is further connected to the secondary side of the exhaust pipe 40, the flow volume Q of the secondary side flow path 36 cannot be controlled based on the surface pressure (pressure difference relative to atmospheric pressure) _ΔP1 in the space 38.

Therefore, when the subsequent device is connected to the secondary-stage side flow path 36, for example, as shown in Figures 4 and 5, an exhaust pipe 40 including an orifice 41 is connected to the exhaust port 313c provided in the fan housing 313 of the exhaust device 31, thereby extending the secondary-stage side flow path 36, and the pressure difference _ΔP2 before and after the orifice 41 is detected as the pressure difference ΔP in the secondary-stage side flow path, and the above-mentioned air volume control for controlling the flow air volume Q is performed based on the pressure difference _ΔP2 before and after the orifice 41.

When the ejector 1 is used within the normal operating temperature range, there is a relationship Q = f(ΔP ₂ ) between the flow volume Q of the secondary side flow path 36 and the pressure difference ΔP ₂ before and after the orifice 41, and the flow volume Q can be obtained as a function of the pressure difference ΔP ₂ before and after the orifice 41.

Therefore, as described above, the change in the pressure difference _ΔP2 before and after the orifice 41 provided at a predetermined position in the secondary-side flow path 36 can be actually controlled as a change in the flow volume Q of the dust collector 30 .

Therefore, as shown in Figure 4, the pressure difference _ΔP2 detected by the pressure difference sensor 52 (pressure detection mechanism 50) for detecting the pressure difference _ΔP2 before and after the orifice 41 is input to the inverter 61, and the inverter 61 is caused to execute PID control for changing the output Inv, so that the input pressure difference _ΔP2 before and after the orifice 41 is close to the target pressure difference _ΔP0 which is pre-stored as the pressure difference corresponding to the target air volume _Q0 , thereby executing air volume control so that the flow air volume Q of the secondary side flow path 36 is as close as possible to the target air volume _Q0 .

In this configuration, as shown in Fig. 4, the pressure difference _ΔP2 before and after the orifice 41 detected by the pressure difference sensor 52 (pressure detection mechanism 50) is directly input to the inverter 61 to control the operation of the fan motor 312 of the dust collector 30. Therefore, the control device 60 that controls the operation of the dust collector 30 only by the inverter 61 is constructed.

As shown in FIG6 , instead of the configuration shown in FIG4 , a calculation device 62 may be provided, which receives the pressure difference _ΔP2 before and after the orifice 41 detected by the pressure difference sensor 52 and calculates the flow air volume Q of the secondary side flow path 36 based on the pressure difference _ΔP2 before and after the orifice 41 and a pre-stored relationship expression Q = f(ΔP). The flow air volume Q obtained as a result of the calculation of the calculation device 62 may be input to the inverter 61, and the inverter 61 may perform the above-mentioned air volume control by using a PID control for changing the output Inv, so that the input flow air volume Q is close to the preset target air volume _Q0 .

In the configuration shown in FIG. 6 , the control device 60 for controlling the operation of the dust collector 30 is constituted by a combination of the arithmetic device 62 and the inverter 61 described above.

As described with reference to Figures 4 and 6, in a configuration in which the flow volume Q is controlled based on the pressure difference _ΔP2 before and after the orifice 41 provided in the flow path 36 on the secondary side, changes in the flow volume Q can be controlled without being affected by changes in the exhaust resistance. Therefore, even when a subsequent device such as a HEPA filter is further connected to the secondary side of the exhaust pipe 40, the flow volume Q can be controlled to be constant.

In addition, because the flow air volume Q can be controlled in a manner that is not affected by the exhaust resistance on the secondary-stage side of the exhaust duct 40, the configuration is not limited to a configuration in which a subsequent device is connected to the secondary-stage side of the exhaust duct 40. Even in the case of a configuration in which the secondary-stage side end of the exhaust duct 40 is open to the atmosphere, the flow air volume Q can be maintained constant.

[other]

Note that in the configuration described with reference to Figures 1 to 6, as the clogging of the dust filter 33 progresses, the output Inv of the inverter 61 increases and the rotation speed of the fan motor 312 increases. Therefore, if the output Inv of the inverter 61 increases infinitely as the clogging progresses, the power of the fan motor 312 is controlled to exceed the rated value.

In addition, since the pressure difference between the primary side and the secondary side of the dust filter 33 increases with the increase of the speed of the fan 311, if the speed of the fan motor 312 increases infinitely, the pressure difference between the primary side and the secondary side of the dust filter 33 will increase to exceed the pressure resistance performance of the dust filter 33, and there is a possibility that the dust filter 33 will be damaged and cannot be used.

Therefore, for example, the inverter 61 of the control device 60 constituting the dust collector 30 may be provided with an upper limit setting mechanism (not shown) for setting an upper limit value of the output Inv, and when the output Inv of the inverter 61 reaches a preset upper limit value taking into account the rated power of the fan motor 312 and the withstand voltage performance of the dust filter 33, the inverter 61 may stop the output to cause the fan motor 312 to stop urgently.

In addition, when the output Inv of the inverter 61 reaches the above-mentioned upper limit value or reaches a predetermined lower value relative to the above-mentioned upper limit value, a warning is issued to the operator by turning on a warning light or generating a warning sound, and the operation of the joystick 35 can be used to help remove the dust accumulated in the dust filter 33 and replace the dust filter 33.

Furthermore, as described above, when the flow air volume Q of the dust filter 33 is excessively increased in the initial use stage when clogging has not occurred, the mesh of the portion where air flows intensively becomes wider and coarser than the mesh of other portions, and the function of the dust filter 33 may be impaired. By setting the flow air volume of the dust collector 30 that causes such coarse meshes to the limit air volume Qmax, and controlling the rotation speed of the fan 311 (including stopping) so that the detected value of the flow air volume Q is less than the value set as the limit air volume Qmax, it is possible to prevent the dust filter 33 from losing its function in the initial use stage.

In addition, in the configuration for detecting the pressure difference _ΔP1 between the pressure in the space 38 between the dust filter 33 and the fan 311 in the secondary side flow path 36 and the atmospheric pressure, the pressure difference _ΔP1 between the pressure in the space 38 and the atmospheric pressure always has a value equal to or greater than the pressure difference before and after the dust filter 33.

Therefore, by measuring in advance the pressure difference before and after the dust filter 33 that will cause damage to the dust filter 33 as the withstand pressure limit pressure difference ΔPfmax, and by controlling the speed of the fan 311 (including stopping) so that the measured value of the pressure difference _ΔP1 between the pressure in the space 38 and the atmospheric pressure is less than the value set as the withstand pressure limit pressure difference ΔPfmax, damage to the dust filter 33 can be prevented.

[Example]

Next, the results of an effect confirmation experiment will be described below. In this effect confirmation experiment, the method of the present invention is used to control the dust collector of the spray device.

The experiments were conducted in two modes, [Experiment 1] and [Experiment 2]. [Experiment 1] corresponds to the device configuration described with reference to FIGS. 1 and 2 , and [Experiment 2] corresponds to the device configuration described with reference to FIGS. 4 and 5 described later.

[Experiment 1]

(1) Experimental equipment

As shown in FIG. 7 , what is to be controlled is a dust collector 30 of an ejection device (“D4715” manufactured by Fuji Manufacturing Co., Ltd.), an exhaust port 313c in which is open to the atmosphere, and a fan motor 312 (rated output 0.75 kW) of the dust collector 30 is controlled by a control device 60 including an operating device (sequencer) 62 and an inverter 61.

The pressure sensor 51 disposed in the exhaust device 31 of the dust collector 30 is configured as a pressure detection mechanism 50, which detects the gauge pressure in the space 38 (see FIG. 2 ) in the pipe 314, and the absolute value of the gauge pressure detected by the pressure detection mechanism 50 (51) is input to the calculation device 62 as the pressure difference _ΔP1 between the pressure in the space 38 and the atmospheric pressure.

The computing device 62 and the inverter 61 are connected to each other in a communicative manner, so that the computing device 62 can monitor the output Inv of the inverter 61 in real time, and the flow air volume Q obtained by the computing device 62 based on the pressure difference ΔP ₁ relative to the atmospheric pressure detected by the pressure detection mechanism 50 (51) and the inverter output Inv and using the pre-stored relationship expression [Q = f(ΔP ₁ , Inv)] can be output to the inverter 61. The inverter 61 is configured to be able to perform air volume control by PID control for changing the output Inv so that the flow air volume Q to be received is close to the preset target air volume Q ₀ .

In order to actually measure the flow air volume of the dust collector 30, anemometers (not shown) are installed at five (5) positions on the same vertical cross section near the exhaust port 313c, and the flow air volume (m3/min) of the dust collector 30 is calculated by multiplying the average value of the air speed measured by the five (5) anemometers by the cross-sectional area of the exhaust port ^313c .

(2) Preliminary preparation

(2-1) Obtaining and setting the relational expression [Q = f(H, Inv)]

By gradually reducing the opening of the inlet 32a of the dust collector 30 shown in FIG. 7, a state in which the dust filter has been clogged is artificially created, so that the pressure difference _ΔP1 between the pressure in the space 38 in the pipe 314 and the atmospheric pressure varies in the range of 1.4 kPa to 1.9 kPa, and the inverter output Inv varies in the range of 0.4 kW to 0.7 kW, and thus the following relationship expression is obtained as Q = f( _ΔP1 , Inv):

Q = 0.55∙Inv/ΔP ₁

The relational expression is stored in the computing device 62.

(2-2) Obtaining and setting the target air volume _Q0

When the inlet 32a of the dust collector 30 is in a fully open state and the commercial power supply (50 Hz, 200 V) is directly connected to the fan motor 312 without inserting the inverter 61 therebetween, the flow air volume 11.44 ^m3 /min (cubic meters/minute) obtained at this time is stored in the inverter 61 as the target air volume _Q0 .

(3) Experimental methods and results

In the dust collector 30 whose fan motor 312 is controlled by the control method of the present invention, the inlet 32a of the dust collector 30 is changed from a fully open state to a half-open state, thereby artificially creating a state in which the clogging of the dust filter 33 has developed, and measuring how the flow air volume (actual measurement value), the air volume change rate (the change rate relative to the fully open state), the pressure difference ΔP ₁ relative to the atmospheric pressure, the inverter output Inv (kW), and the inverter output frequency (Hz) change.

As a comparative example, for a dust collector 30 that is driven by directly connecting the fan motor 312 of the dust collector 30 to a commercial power source (50 Hz, 200 V) without inserting an inverter 61 therebetween, the inlet 32a of the dust collector 30 is changed from a fully open state to a half-open state, and the flow air volume (actual measured value) and the air volume change rate (change rate relative to the fully open state) are measured.

The measurement results are shown in Table 1 below.

[Table 1] Results of Experiment 1 Measurement items The invention Comparison Example Import opening Full Half open Full Half open Flow air volume (m ³ /min) 11.62 11.27 11.44 10.12 Air volume change rate (%) ---- -3.0 ---- -11.5 Pressure difference relative to atmospheric pressure ΔP ₁ (Pa) 1414 1780 Inverter output (kW) 0.50 0.64 Inverter frequency (Hz) 50.0±1 54.5±1

According to the above results, in the dust collector (comparative example) not implementing the control of the present invention, the flow volume is 11.44 ^m3 /min when the inlet 32a is fully opened, and the flow volume is reduced to 10.12 ^m3 /min when the inlet 32a is half opened, that is, it is reduced by 11.5%.

In contrast, in the dust collector controlled by the method of the present invention, the flow air volume is 11.62 ^m3 /min when the inlet 32a is fully opened, and the flow air volume is reduced to 11.27 ^m3 /min when the inlet 32a is half opened, that is, a decrease of 3%. Therefore, it can be confirmed that the flow air volume of the dust collector 30 can be maintained constant with high precision.

In addition, in the dust collector controlled by the method of the present invention, even when the opening area of the inlet 32a of the dust collector is reduced to half of the opening, the flow air volume can be controlled to be basically constant, from which it is obvious that not only the reduction of the flow air volume due to the blockage of the dust filter can be prevented, but also the overall reduction of the air volume due to the reduction of the flow path area on the main stage side of the measurement position of the pressure difference _ΔP1 (for example, the narrowing of the flow path area caused by the adhesion of the sprayed material or dust to the inner wall of the collection pipe or the exhaust pipe) can be prevented.

[Experiment 2]

(3) Experimental equipment

The experiment was conducted using the experimental apparatus shown in Fig. 8. The dust collector 30 to be controlled in the experimental apparatus was a dust collector in an ejector device ("D4715" manufactured by Fuji Seisakusho Co., Ltd.) having a fan motor with a rated output of 0.75 kW, and an inverter 61 was connected to the fan motor 312 of the dust collector as the control device 60.

An exhaust pipe 40 including an orifice 41 is connected to the exhaust port 313c of the dust collector 30 to extend the secondary-side flow path 36. In addition, a pressure differential sensor 52 for detecting the pressure difference _ΔP2 before and after the orifice 41 is provided as a pressure detection mechanism 50 in the exhaust pipe 40 for constituting the secondary-side flow path 36.

The pressure difference _ΔP2 before and after the orifice 41 detected by the pressure difference sensor 52 is input to the inverter 61, and the inverter 61 is configured to perform air volume control by PID control for changing the output Inv so that the input pressure difference _ΔP2 before and after the orifice 41 approaches the preset target pressure difference _ΔP0 .

In order to actually measure the flow air volume of the dust collector 30, anemometers (not shown) are installed at five (5) positions on the same vertical cross section near the outlet of the exhaust duct 40 (positions far enough away from the orifice 41 and will not affect the measurement of the pressure difference _ΔP2 before and after the orifice 41), and the flow air volume ( ^m3 /min) of the dust collector is calculated by multiplying the average value of the air speed measured by the five (5) anemometers by the cross-sectional area of the exhaust duct 40.

(2) Preliminary preparation

(2-2) Obtaining and setting the target pressure difference ΔP ₀

When the inlet 32a of the dust collector 30 is in a fully open state and the commercial power supply (50Hz, 200V) is directly connected to the fan motor 312 without an inverter inserted therebetween, the 260 Pa (Pa) differential pressure ΔP2 before and after the orifice 41 detected by the differential pressure sensor ₅₂ is stored in the inverter 61 as the target differential pressure _ΔP0 .

(3) Experimental methods and results

The inlet 32a of the dust collector 30 controlled according to the method of the present invention is changed from a fully open state to a half-open state, thereby artificially creating a state in which the clogging of the dust filter has developed, and measuring how the flow air volume (actual measurement value), the air volume change rate (the change rate relative to the fully open state), the pressure difference _ΔP2 (Pa) before and after the orifice, the inverter output Inv (kW), and the inverter output frequency (Hz) change.

As a comparative example, for a dust collector that is driven by directly connecting the fan motor 312 to a commercial power source (50 Hz, 200 V) without inserting an inverter 61 therebetween, the inlet 32a of the dust collector is changed from a fully open state to a half-open state, and the flow air volume (actual measured value) and the air volume change rate (change rate relative to the fully open state) are measured.

The measurement results are shown in Table 2 below.

[Table 2] Results of Experiment 2 Measurement items The invention Comparison Example Import opening Full Half open Full Half open Flow air volume (m ³ /min) 10.85 10.89 10.81 9.49 Air volume change rate (%) ---- 0.4 ---- -12.2 Pressure difference before and after the orifice ΔP ₂ (Pa) 260 260 Inverter output (kW) 0.50 0.65 Inverter frequency (Hz) 50.3±0.2 55.6±0.2

According to the above results, in the dust collector (comparative example) not implementing the control of the present invention, the flow volume is 10.81 ^m3 /min when the inlet 32a is fully opened, and the flow volume is reduced to 9.49 ^m3 /min when the inlet 32a is half opened, that is, it is reduced by 12.2%.

In contrast, in the dust collector controlled by the method of the present invention, the flow air volume is 10.85 ^m3 /min when the inlet 32a is fully opened, and the flow air volume is reduced to 10.89 ^m3 /min when the inlet 32a is half opened, that is, it decreases by 0.4%. Therefore, it can be confirmed that the flow air volume of the dust collector can be maintained constant with high precision.

In addition, the flow air volume can be controlled to be basically constant even when the opening area of the inlet of the dust collector is half open. It is obvious that the configuration of the present experimental example for controlling the speed of the fan motor based on the pressure difference ΔP before and after the orifice of the dust collector is not only capable of coping with the reduction in flow air volume due to blockage of the dust filter, but also capable of coping with the overall reduction in air volume due to the reduction in flow path area generated on the main stage side at the measurement position of the pressure difference ΔP ₂ (for example, the narrowing of the flow path area caused by the spraying material or dust adhering to the inner wall of the collection duct or the exhaust duct, etc.).

Therefore, the broadest claims are not directed to a device configured in a particular way. Instead, the broadest claims are intended to protect the core or essence of the breakthrough invention. The invention is clearly new and useful. Moreover, the invention was not obvious to a person of ordinary skill in the art when it was made, taking into account the prior art as a whole.

Furthermore, given the innovative nature of the present invention, it is clearly a groundbreaking invention. Therefore, the appended claims are legally entitled to a very broad interpretation to protect the core of the invention.

Therefore, it can be seen that the above-mentioned objects and other objects obvious from the foregoing description can be effectively achieved, and since certain changes can be made in the above-mentioned structure without departing from the scope of protection of the present invention, all matters contained in the foregoing description or shown in the accompanying drawings should be interpreted as illustrative rather than restrictive.

It should also be understood that the appended claims are intended to cover all generic and specific features of the invention described herein, as well as all statements of the scope of protection of the invention that can be considered to fall between the two in terms of language.

In summary, the present invention has been described.

1: Blasting apparatus 10: Chassis 10a: Bottom 11: Working space 12: Blasting nozzle 13: Collecting pipe 20: Classifier 21: Exhaust pipe 22: Blasting material tank 23: Blasting material hose 30: Dust collector 31: Air exhaust device 311: Fan 312: Fan motor 313: Fan housing 313a: Inlet 313b: Accommodating space 313c: Exhaust port 314: Pipe 32: Filter housing 32a: Inlet 32b: Outlet 33: Dust collecting filter 35: Shaking lever 36: Secondary side flow path 38: Space 40: Exhaust pipe 41: Orifice 50: Pressure detection mechanism 51: Single pressure sensor 52: Pressure difference sensor 60: Control device 61: Inverter 62: Calculation device (sequencer) ΔP: Pressure difference ΔP ₁ : Pressure difference (pressure difference between the pressure in space 38 and atmospheric pressure) ΔP ₂ : Pressure difference (pressure difference before and after the orifice) ΔP ₀ : Target pressure difference Q: Passing air volume Q ₀ : Target air volume

The objects and advantages of the present invention will be understood from the following detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings, in which like numerals represent like elements, and in which:

FIG. 1 is an explanatory diagram showing a configuration example of a dust collector and a control device in the case of performing air volume control based on a pressure difference _ΔP1 between the pressure of a secondary-stage side flow path and atmospheric pressure.

FIG. 2 is a cross-sectional view of the fan portion of the dust collector used in the configuration of FIG. 1 .

FIG3 is a graph showing an example of the relationship among the pressure difference ΔP ₁ between the pressure in the space 38 and the atmospheric pressure, the flow volume Q, and the power W (W ₀ , W _{0+ δ} , W _{0+2 δ} ) of the fan motor.

FIG. 4 is an explanatory diagram showing one configuration example of a dust collector and a control device in the case of performing air volume control based on a pressure difference _ΔP2 before and after an orifice provided in a secondary-stage side flow path.

FIG. 5 is a cross-sectional view of a fan portion of a dust collector used in the configuration of FIG. 4 .

FIG. 6 is an explanatory diagram showing another configuration example of the dust collector and the control device in the case of performing air volume control based on the pressure difference _ΔP2 before and after the orifice provided in the secondary-stage side flow path.

FIG. 7 is an explanatory diagram of the experimental apparatus used in [Experiment 1].

FIG. 8 is an explanatory diagram of the experimental apparatus used in [Experiment 2].

FIG. 9 is an explanatory diagram of a (circulating) injection device.

FIG. 10 is a schematic diagram showing changes in the flow air volume of a conventional dust collector (when dust is periodically removed by a rocker).

30: Dust collector

311: Fan

312: Fan motor

313: Fan housing

313c: Exhaust outlet

314: Pipeline

36: Secondary side flow path

38: Space

50: Pressure detection mechanism

51: Single pressure sensor

60: Control device

61: Inverter

62: Operation device (sequencer)

△P ₁ : Pressure difference (pressure difference between the pressure in space 38 and atmospheric pressure)

Q: Passing air volume

Q ₀ : Target air volume

Claims (14)

A dust collector control method in a spraying device, the spraying device is provided with: a cabinet containing a working space; a classifier, which includes a wind classifier, the wind classifier introduces and classifies the spraying material sprayed and collected together with the dust in the cabinet; a spraying material tank, which stores the reusable spraying material after being classified by the classifier; and a dust collector, which includes a fan, the fan sucks and exhausts the air from the classifier, the spraying device utilizes the spraying material collected by the classifier. The airflow generated in the classifier by the suction of the dust collector collects the reusable spray material into the spray material tank through wind sorting, and the control method includes: detecting the pressure difference in the secondary-stage side flow path, the secondary-stage side flow path is the flow path arranged at the secondary-stage side of the dust filter of the dust collector; and executing air volume control for controlling the rotation speed of the fan, so that the flow air volume of the dust collector controlled based on the detected pressure difference is close to the preset target air volume. The dust collector control method in the spray device according to claim 1, wherein the control method comprises: arranging the fan in the secondary-side flow path, and opening the secondary-side flow path to the atmosphere at the secondary-side of the fan; detecting the pressure difference between the pressure in the space between the dust filter and the fan in the secondary-side flow path and the atmospheric pressure; The method comprises the steps of: calculating the flow air volume of the dust collector according to the pressure difference between the detected pressure in the space and the atmospheric pressure and the rotation speed of the fan when the pressure difference is detected and based on a preset relationship expression; and performing air volume control for controlling the rotation speed of the fan so that the calculated flow air volume is close to the target air volume. A dust collector control method in an injection device according to claim 1, wherein the control method includes: detecting a pressure difference before and after an orifice arranged in the secondary-stage side flow path as the pressure difference in the secondary-stage side flow path; and performing air volume control for controlling the rotation speed of the fan so that the detected pressure difference before and after the orifice is close to a preset target pressure difference, and the preset target pressure difference is the pressure difference before and after the orifice corresponding to the target air volume, thereby making the flow air volume close to the target air volume. A dust collector control method in an injection device according to claim 1, wherein the control method includes: detecting a pressure difference before and after an orifice arranged in the secondary-stage side flow path as the pressure difference in the secondary-stage side flow path; calculating the flow air volume of the dust collector based on the detected pressure difference before and after the orifice and a preset relationship expression; and executing air volume control for controlling the rotation speed of the fan so that the calculated flow air volume is close to the target air volume. A dust collector control method in a spray device according to any one of claims 1 to 4, wherein the control method comprises: setting the flow air volume of the dust collector to a limit air volume which will cause the dust filter to have a coarse mesh in the initial use phase; and controlling the rotation speed of the fan so that the flow air volume is less than the limit air volume. A dust collector control method in an injection device according to claim 2, wherein the control method includes: measuring in advance the pressure difference before and after the dust filter that will cause damage to the dust filter as the withstand pressure limit pressure difference; and controlling the rotation speed of the fan so that the measured value of the pressure difference between the pressure in the space between the dust filter and the fan in the secondary side flow path and the atmospheric pressure is less than the value set as the withstand pressure limit pressure difference. A dust collector control method in a spray device according to any one of claims 1 to 4, wherein when the speed of the fan reaches a predetermined upper speed limit, the fan is stopped urgently. A spraying device is provided with: a cabinet containing a working space; a classifier, which includes a wind classifier, and the wind classifier introduces and classifies the spraying material sprayed and collected together with dust in the cabinet; a spraying material tank, which stores the reusable spraying material after being classified by the classifier; and a dust collector, which includes a fan, and the fan sucks and discharges the air from the classifier. The spraying device uses the air generated in the classifier due to the suction of the dust collector. The airflow passes through wind sorting to collect reusable spraying materials into the spraying material tank, and the spraying device includes: a pressure detection mechanism, which detects the pressure difference in the secondary-stage side flow path, and the secondary-stage side flow path is a flow path arranged at the secondary-stage side of the dust filter of the dust collector; and a control device, which performs air volume control for controlling the rotation speed of the fan so that the flow air volume of the dust collector controlled based on the pressure difference detected by the pressure detection mechanism is close to the preset target air volume. The spray device according to claim 8, wherein the fan is disposed in the secondary-side flow path, and the secondary-side flow path is open to the atmosphere at the secondary-side of the fan, and a pressure sensor for detecting a pressure difference between a pressure in a space between the dust filter and the fan in the secondary-side flow path and atmospheric pressure is disposed as the pressure sensor. The detection mechanism comprises a control device for calculating the flow air volume of the dust collector according to the pressure difference relative to the atmospheric pressure detected by the pressure sensor and the rotation speed of the fan when the pressure difference is detected and based on a preset relationship expression, and the control device performs air volume control for controlling the rotation speed of the fan so that the calculated flow air volume approaches the target air volume. The injection device according to claim 8, wherein the pressure detection mechanism is a pressure differential sensor that detects the pressure differential before and after an orifice arranged in the secondary-stage side flow path, and the control device performs air volume control for controlling the rotation speed of the fan so that the pressure differential before and after the orifice detected by the pressure differential sensor is close to a preset target pressure differential, and the preset target pressure differential is the pressure differential before and after the orifice corresponding to the target air volume, thereby performing control for making the flow air volume close to the target air volume. The injection device according to claim 8, wherein the pressure detection mechanism is a pressure differential sensor that detects the pressure differential before and after an orifice arranged in the secondary side flow path, and the control device calculates the flow air volume of the dust collector based on the pressure differential before and after the orifice detected by the pressure differential sensor and based on a preset relationship expression, and the control device performs air volume control for controlling the rotation speed of the fan so that the calculated flow air volume is close to the target air volume. A spray device according to any one of claims 8 to 10, wherein the control device stores the flow air volume of the dust collector which would cause the dust filter to have a coarse mesh in the initial use phase as the maximum air volume, and the control device controls the rotation speed of the fan so that the flow air volume is less than the maximum air volume. The spray device according to claim 9, wherein the control device stores the pressure difference before and after the dust filter that may cause damage to the dust filter as a withstand pressure limit pressure difference, and the control device controls the rotation speed of the fan so that the measured value of the pressure difference between the pressure in the space between the dust filter and the fan in the secondary side flow path and the atmospheric pressure is less than the withstand pressure limit pressure difference. A spray device according to any one of claims 8 to 11, wherein when the speed of the fan reaches a predetermined upper speed limit, the control device causes the fan to stop urgently.