Reverse-pressure cleaning device for dust collector

Abstract

To achieve energy saving by enabling control of air consumption amount while maintaining a reverse-pressure cleaning effect of a filter even when a compressor is shared with other devices.SOLUTION: A reverse-pressure cleaning device 1 for a dust collector comprises: a buffer tank 2; an air pipe 3 that injects compressed air in the buffer tank 2 toward a filter 200; an electromagnetic valve 4 that opens and closes the air pipe 3; a pressure measurement section 5 that measures pressure of compressed air in the buffer tank 2; and a control section 6 that controls the electromagnetic valve 4 so that, when it is determined that the pressure of compressed air is equal to or lower than a predetermined value, an opening time becomes longer than when the pressure of compressed air is higher than the predetermined value.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a backpressure cleaning device that uses compressed air to backpressure clean a filter included in a dust collector. [Background technology]

[0002] Conventionally, in order to obtain a stable dust collection effect by the filter of a dust collector over a long period of time, backpressure cleaning of the filter with compressed air has been performed periodically or irregularly. For example, Patent Document 1 discloses an air pressure regulating device for backpressure cleaning of a filter. In this air pressure regulating device, a pressure sensor that detects air pressure is provided in a header pipe that temporarily stores compressed air supplied from a compressor. When the pressure value detected by the pressure sensor is below a specified value, an adjusting solenoid valve is opened to replenish air from the compressor to the header pipe, thereby increasing the air pressure in the header pipe to a pressure suitable for backpressure cleaning. This automatically adjusts the air pressure to the specified value, allowing the filter to be properly cleaned. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 62-174618 Summary of the Invention [Problem to be solved by the invention]

[0004] The backpressure cleaning device is provided with a buffer tank (corresponding to the header pipe in Patent Document 1) for temporarily storing the compressed air supplied from the compressor, and an electromagnetic valve is controlled so that the compressed air in this buffer tank is sprayed toward the filter for a predetermined period of time.

[0005] In large facilities such as rice milling factories, the compressed air supplied from the compressor is not used solely by the backpressure cleaning system, but is also shared with other equipment such as rice mills and optical sorters. As a result, it is inevitable that the pressure in the buffer tank of the backpressure cleaning system will change depending on the amount of compressed air used by each piece of equipment.

[0006] Therefore, if the back pressure cleaning of the filter is set to inject air for a fixed period of time using timer control, back pressure cleaning with low-pressure air will result in a reduced cleaning effect of the filter if the pressure inside the buffer tank is low. To address this, it is possible to set the injection time longer so that sufficient cleaning effect can be obtained even at low pressure, but this will result in more compressed air being injected than necessary if the pressure inside the buffer tank is sufficiently high, resulting in wasted compressed air and ultimately increased energy consumption by the facility.

[0007] The present disclosure has been made in consideration of such points, and has as its technical objective to achieve energy savings by making it possible to control air consumption while maintaining the backpressure cleaning effect of the filter, even when the compressor is shared with other equipment, for example. [Means for solving the problem]

[0008] To achieve the above object, one aspect of the present disclosure can be based on a backpressure cleaning device for a dust collector that backpressure cleans a filter of a dust collector with compressed air. The backpressure cleaning device for a dust collector includes: a buffer tank that stores compressed air supplied from a compressor; an air pipe connected to the buffer tank and formed with an injection port that injects the compressed air in the buffer tank toward the filter in a direction opposite to the inflow direction of the fluid to be filtered; a solenoid valve that opens and closes the air pipe; a pressure measuring unit that measures the pressure of the compressed air in the buffer tank; and a control unit that determines whether the pressure of the compressed air measured by the pressure measuring unit is equal to or lower than a predetermined value, and that controls the solenoid valve so that the open time is longer when it is determined that the pressure of the compressed air is equal to or lower than the predetermined value.

[0009] With this configuration, when the solenoid valve is opened, compressed air supplied from the compressor and stored in the buffer tank flows through the air piping and is sprayed onto the filter from the nozzle. The direction of the compressed air spray is opposite to the direction in which the fluid to be filtered flows into the filter, enabling backpressure cleaning of the filter. When the pressure of the compressed air in the buffer tank is higher than a predetermined value, the solenoid valve's open time is set to inject the minimum amount of air necessary to maintain the filter's cleaning effect. This prevents unnecessary spraying of compressed air and avoids unnecessary air consumption.

[0010] On the other hand, if another device is connected between the compressor and the buffer tank and uses a large amount of air, the compressed air pressure in the buffer tank may temporarily drop below a predetermined value. In this case, the control unit controls the solenoid valve so that the open time is longer than when the compressed air pressure is higher than the predetermined value, increasing the amount of compressed air injected toward the filter. This allows the amount of compressed air injected to compensate for the drop in compressed air pressure, maintaining the backpressure cleaning effect.

[0011] When the control unit determines that the pressure of the compressed air measured by the pressure measuring unit is below a predetermined value, the control unit can also control the solenoid valve so that the closing time is shorter than when the pressure of the compressed air is higher than the predetermined value.

[0012] The control unit repeatedly switches the solenoid valve between open and closed states, and when it is determined that the pressure of the compressed air measured by the pressure measuring unit is below a predetermined value, the control unit can shorten the time interval for switching the solenoid valve from a closed state to an open state compared to when the pressure of the compressed air is higher than the predetermined value.

[0013] In other words, by shortening the time the solenoid valve is closed when the pressure of the compressed air is below a predetermined value and shortening the time interval when switching the solenoid valve from a closed state to an open state, the frequency with which the solenoid valve opens can be increased, thereby making it possible to compensate for a drop in the pressure of the compressed air by increasing the amount of compressed air injected.

[0014] The control unit may execute a first determination process to determine whether the pressure of the compressed air measured by the pressure measuring unit is equal to or less than a first predetermined value, a second determination process to determine whether the pressure is higher than the first predetermined value and equal to or less than a second predetermined value, and a third determination process to determine whether the pressure is higher than the second predetermined value.

[0015] In this case, when the first determination process determines that the pressure of the compressed air is equal to or lower than the first predetermined value, the control unit can control the solenoid valve so that the opening time is longer than when the second determination process determines that the pressure of the compressed air is higher than the first predetermined value and equal to or lower than the second predetermined value, and when the third determination process determines that the pressure of the compressed air is higher than the second predetermined value.

[0016] By setting the compressed air pressure judgment value in multiple stages in this way, it becomes possible to finely control the compressed air pressure, thereby achieving an even more pronounced effect of maintaining the backpressure cleaning effect of the filter while controlling air consumption and achieving energy savings.

[0017] The air piping may be formed to extend in a column direction of a plurality of filters arranged in a matrix, and may include a downstream pipe section in which a plurality of the injection ports are formed corresponding to the plurality of filters arranged in the column direction. The downstream pipe section includes a first downstream pipe section and a second downstream pipe section arranged in parallel in the row direction of the plurality of filters arranged in the matrix, and the solenoid valve includes a first solenoid valve that opens and closes the first downstream pipe section and a second solenoid valve that opens and closes the second downstream pipe section. In this case, the control unit can individually control the first solenoid valve and the second solenoid valve. By opening the second solenoid valve when the first solenoid valve is closed and opening the first solenoid valve when the second solenoid valve is closed, pressure fluctuations of the compressed air in the buffer tank are reduced compared to when both the first solenoid valve and the second solenoid valve are opened at the same time, and the filter cleaning effect can be achieved as intended. [Effects of the Invention]

[0018] As explained above, when the pressure of the compressed air in the buffer tank is equal to or lower than a predetermined value, the open time of the solenoid valve can be made longer than when the pressure is higher than the predetermined value. Therefore, even when the compressor is shared with other equipment, for example, it is possible to maintain the back pressure cleaning effect of the filter while controlling the amount of air consumption, thereby achieving energy savings. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a perspective view showing a part of a backpressure cleaning device for a dust collector according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram of a back pressure cleaning device for a dust collector. [Figure 3]FIG. 3 is a flowchart showing the flow of the main control. [Figure 4] FIG. 4 is a flowchart showing the flow of the opening and closing control of the solenoid valve. [Figure 5] FIG. 5 is a graph showing the relationship between time and the pressure of compressed air in the buffer tank. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present invention, its applications, or its uses.

[0021] Fig. 1 shows a part of a backpressure cleaning apparatus 1 for a dust collector according to an embodiment of the present invention, and Fig. 2 is a block diagram of the backpressure cleaning apparatus 1 for a dust collector. In the following description, the backpressure cleaning apparatus 1 for a dust collector will be simply referred to as the backpressure cleaning apparatus 1.

[0022] The dust collector 100 that is back-pressure cleaned by the back-pressure cleaning device 1 may be, for example, a dust collector dedicated to rice polishing machines that collects bran generated during rice polishing, but is not limited to dust collectors dedicated to rice polishing machines, and may be any dust collector that filters various types of filtered fluids and collects dust and other particles contained in the filtered fluids.

[0023] 1, dust collector 100 has a vertically elongated shape. The lower portion of dust collector 100 is inlet section 101, into which the fluid to be filtered flows. A connection port 101a is formed in the side wall of inlet section 101, to which an inlet pipe (not shown) for the fluid to be filtered is connected. Therefore, the fluid to be filtered sent from, for example, a rice polisher, is introduced into inlet section 101 from the side of inlet section 101.

[0024] A filter accommodating section 102 is provided in an upper portion of the inlet section 101. In this embodiment, the filter accommodating section 102 has the shape of a rectangular parallelepiped box that is long in the vertical direction. In Fig. 1, one of the four side plates 102a that form the filter accommodating section 102 is shown removed, and therefore the internal structure of the filter accommodating section 102 is shown by solid lines.

[0025] The lower end of the filter accommodating section 102 communicates with the upper end of the inlet section 101, so that the fluid to be filtered that has flowed into the inlet section 101 can flow into the filter accommodating section 102 from the lower end. An outlet section (not shown) is provided at the upper end of the filter accommodating section 102. A filter mounting plate 103, to which multiple filters 200 are attached, is disposed near the upper end of the filter accommodating section 102. The filter mounting plate 103 extends horizontally. The peripheral edge of the filter mounting plate 103 is supported on the inner surface of the filter accommodating section 102, and the gap between the peripheral edge of the filter mounting plate 103 and the inner surface of the filter accommodating section 102 is sealed to prevent the fluid to be filtered from passing through.

[0026] The filter 200 is a bag filter made of a cylindrical filter material that extends in the vertical direction. The upper end of the filter 200 is open, while the lower end is closed. The peripheral edge of the upper end of the filter 200 is fixed to the filter mounting plate 103, and while fixed to the filter mounting plate 103, the open portion of the upper end of the filter 200 is positioned so that it faces upward from the upper surface of the filter mounting plate 103. Therefore, the fluid to be filtered that flows into the filter accommodating section 102 from below the filter accommodating section 102 passes through the filter 200 and is filtered, then flows from the upper end of the filter 200 upward above the filter mounting plate 103, and then flows out from the outlet.

[0027] FIG. 2 shows the arrangement of a plurality of filters 200, and illustrates the filter mounting plate 103 on which the plurality of filters 200 are attached as viewed from directly above. The number of filters 200 can be set as desired. In the example shown in FIG. 2, the plurality of filters 200 are arranged in a matrix (rows and columns). In the description of this embodiment, the column direction of the plurality of filters 200 is defined as the left-right direction in FIG. 2, and the row direction of the plurality of filters 200 is defined as the up-down direction in FIG. 2, but this definition is for convenience of description, and the row direction and column direction can be defined as desired.

[0028] In this embodiment, a case will be described in which a plurality of filters 200 are arranged in five columns and five rows, for a total of 25 filters 200, but the number of columns and rows of the filters 200 can be set as desired. The number of columns and rows of the filters 200 may be the same or different. Also, only one column or one row of filters 200 may be provided. Furthermore, only one filter 200 may be provided.

[0029] The backpressure washing device 1 is a device for backpressure washing a plurality of filters 200. Backpressure washing is the process of supplying a washing fluid in the opposite direction to the flow direction of the fluid to be filtered during filtration, and maintaining the filtering performance by using the washing fluid to remove dust and other particles captured on the filters 200. In this embodiment, the fluid to be filtered flows from below to above, so during backpressure washing, the washing fluid is supplied from above to below.

[0030] The backpressure washing device 1 uses compressed air as a cleaning fluid. As shown in Fig. 2, the backpressure washing device 1 includes a buffer tank 2, an air pipe 3, a solenoid valve 4, a pressure measurement unit 5, and a control unit 6. The buffer tank 2 is used to store compressed air supplied from a compressor 300. Specifically, the buffer tank 2 and the compressor 300 are connected by an air supply pipe 301, and compressed air discharged from the compressor 300 is supplied to the buffer tank 2 via a pressure adjustment valve (not shown) or the like. The compressed air in the buffer tank 2 is a cleaning fluid and is sprayed onto the filter 200 via the air pipe 3.

[0031] In this embodiment, other devices 302 and 303 are connected to the middle of the air supply pipe 301. The other devices 302 and 303 are, for example, rice polishers or optical sorters, and are devices that use compressed air. Because the backpressure cleaning apparatus 1 shares the compressed air supplied from the compressor 300 with the other devices 302 and 303, the pressure in the buffer tank 2 of the backpressure cleaning apparatus 1 may change depending on the amount of compressed air used by each device 302 and 303. Specifically, the greater the amount of compressed air used by each device 302 and 303, the lower the pressure in the buffer tank 2 may become. A decrease in the pressure in the buffer tank 2 reduces the amount of compressed air supplied per unit time from the air pipe 3 to the filter 200, weakening the force of the compressed air and potentially reducing the backpressure cleaning effect. The backpressure cleaning apparatus 1 of this embodiment is capable of maintaining the backpressure cleaning effect of the filter 200 even when the pressure in the buffer tank 2 decreases. A specific configuration will be described below.

[0032] The upstream side of the air pipe 3 is connected to the buffer tank 2. The air pipe 3 branches into first to fifth downstream pipe sections 31 to 35 midway. The number of downstream pipe sections 31 to 35 is set to be the same as the number of rows of the filters 200, and therefore may be changed according to the number of rows of the filters 200. The first to fifth downstream pipe sections 31 to 35 are formed so as to extend in the column direction of the plurality of filters 200 arranged in a matrix, and are arranged in parallel in the row direction of the plurality of filters 200. The first to fifth downstream pipe sections 31 to 35 are held by, for example, the filter receiving section 102 of the dust collector 100.

[0033] The first downstream pipe section 31 is disposed directly above the first row of filters 200 (the uppermost row in FIG. 2) and spaced upward from the upper ends of the filters 200. Five first injection ports 31a are formed in the lower part of the first downstream pipe section 31, corresponding to the five filters 200 aligned in the row direction of the first row. In plan view, each first injection port 31a is positioned at or near the center of each filter 200 in the first row.

[0034] The second downstream pipe section 32 is disposed directly above the second row of filters 200 (the second row from the top in FIG. 2 ), with a gap therebetween above the upper ends of the filters 200. Five second injection ports 32a are formed in the lower part of the second downstream pipe section 32, corresponding to the five filters 200 aligned in the row direction of the second row. In plan view, each second injection port 32a is positioned at or near the center of each filter 200 in the second row.

[0035] The third downstream pipe section 33 is disposed directly above the third row of filters 200 (the third row from the top in FIG. 2 ), with a gap therebetween above the upper end of the filters 200. Five third injection ports 33a are formed in the lower part of the third downstream pipe section 33, corresponding to the five filters 200 aligned in the row direction of the third row. In plan view, each third injection port 33a is positioned at or near the center of each filter 200 in the third row.

[0036] The fourth downstream pipe section 34 is disposed directly above the fourth row of filters 200 (the fourth row from the top in FIG. 2 ), with a gap therebetween above the upper ends of the filters 200. Five fourth injection ports 34a are formed in the lower part of the fourth downstream pipe section 34, corresponding to the five filters 200 aligned in the row direction of the fourth row. In plan view, each fourth injection port 34a is positioned at or near the center of each filter 200 in the fourth row.

[0037] The fifth downstream pipe section 35 is disposed directly above the fifth row of filters 200 (the lowest row in FIG. 2 ), with a gap above the upper end of the filters 200. Five fifth jetting orifices 35a are formed in the lower part of the fifth downstream pipe section 35, corresponding to the five filters 200 aligned in the row direction of the fifth row. In plan view, each fifth jetting orifice 35a is positioned at or near the center of each filter 200 in the fifth row. In this way, because the jetting orifices 31a to 35a are disposed directly above all of the filters 200, compressed air can be reliably injected onto each filter 200, thereby backpressure cleaning all of the filters 200.

[0038] The solenoid valve 4 is a flow path opening / closing valve for opening and closing the air pipe 3, and includes first to fifth solenoid valves 41 to 45. The first solenoid valve 41 is provided in a portion of the first downstream pipe section 31 upstream of the first injection port 31a and opens and closes the first downstream pipe section 31. The second solenoid valve 42 is provided in a portion of the second downstream pipe section 32 upstream of the second injection port 32a and opens and closes the second downstream pipe section 32. The third solenoid valve 43 is provided in a portion of the third downstream pipe section 33 upstream of the third injection port 33a and opens and closes the third downstream pipe section 33. The fourth solenoid valve 44 is provided in a portion of the fourth downstream pipe section 34 upstream of the fourth injection port 34a and opens and closes the fourth downstream pipe section 34. The fifth solenoid valve 45 is provided in a portion of the fifth downstream pipe section 35 upstream of the fifth injection port 35a and opens and closes the fifth downstream pipe section 35. In this way, the first to fifth solenoid valves 41 to 45 are provided separately and operate separately. The number of solenoid valves 4 only needs to match the number of downstream pipe sections, so if there is one downstream pipe section, there will also be one solenoid valve 4.

[0039] The pressure measurement unit 5 is composed of a pressure sensor and the like that measures the pressure of the compressed air inside the buffer tank 2. A measurement signal corresponding to the pressure of the compressed air inside the buffer tank 2 is output from the pressure measurement unit 5. Since the pressure measurement by the pressure measurement unit 5 is performed in approximately real time, the current pressure state inside the buffer tank 2 can be obtained from the measurement signal output from the pressure measurement unit 5. The pressure measurement unit 5 may be attached to the buffer tank 2, or may be attached to a pipe that communicates with the buffer tank 2.

[0040] The control unit 6 is connected to the first to fifth solenoid valves 41 to 45 and controls the first to fifth solenoid valves 41 to 45 individually. The control unit 6 includes, for example, a microcomputer that operates according to a pre-stored program, and specifically can be configured with a program relay or the like, but is not limited to this. The pressure measurement unit 5 is connected to the control unit 6, and the control unit 6 is able to receive a measurement signal output from the pressure measurement unit 5.

[0041] FIG. 3 is a flowchart showing the flow of main control by the control unit 6. This flow may start, for example, when the dust collector 100 starts operating, or when a user performs an operation to start the backpressure cleaning device 1. In step SA1, the first solenoid valve 41 is controlled, in step SA2 the second solenoid valve 42 is controlled, in step SA3 the third solenoid valve 43 is controlled, in step SA4 the fourth solenoid valve 44 is controlled, and in step SA5 the fifth solenoid valve 45 is controlled. The flow then returns to step SA1. In this manner, the control unit 6 sequentially controls the first through fifth solenoid valves 41 through 45, repeatedly switching between open and closed states of the first through fifth solenoid valves 41 through 45, thereby sequentially backpressure cleaning the first through fifth rows of filters 200. Among the first through fifth solenoid valves 41 through 45, solenoid valves that are not being controlled are maintained in a closed state. The order in which the control unit 6 controls the solenoid valves 41 through 45 is not limited to the above-described order and may be any order.

[0042] Furthermore, for example, in a facility where a rice polisher and dust collector 100 are used as a set, the backpressure cleaning device 1 may determine whether the rice polisher is polishing rice or not, and if the rice polisher is not polishing rice, stop control of the first to fifth solenoid valves 41 to 45. For example, when changing the rice variety, there will be a period of time when rice is not polished, and during such a period, stop control of the first to fifth solenoid valves 41 to 45 to reduce wasteful consumption of compressed air.

[0043] Details of step SA1 in Fig. 3 will be explained based on the flowchart shown in Fig. 4. In this flowchart, a set pressure A (first predetermined value), a set pressure B (second predetermined value), and a set pressure C (third predetermined value) are used as pressure determination thresholds. The set pressure A is the smallest, the set pressure C is the largest, and the set pressure B is a pressure between the set pressures A and C. The specific values ​​of the set pressure A, the set pressure B, and the set pressure C are not particularly limited, but as an example, the set pressure A is 0.5 MPa, the set pressure B is 0.55 MPa, and the set pressure C is 0.6 MPa.

[0044] Furthermore, this flowchart uses opening times T1 (first opening time), T3 (second opening time), T5 (third opening time), and T7 (fourth opening time) to open the solenoid valve. Opening time T1 is the longest, and opening time T7 is the shortest. Opening time T3 is shorter than opening time T1 and longer than opening time T5. Opening time T5 is shorter than opening time T3 and longer than opening time T7. The specific times for opening times T1, T3, T5, and T7 are not particularly limited, but, by way of example, opening time T1 is 1.6 seconds, opening time T3 is 1.4 seconds, opening time T5 is 1.2 seconds, and opening time T7 is 1.0 second.

[0045] Furthermore, this flowchart uses closing times T2 (first closing time), T4 (second closing time), T6 (third closing time), and T8 (fourth closing time) to close the solenoid valve. Closing time T8 is the longest, and closing time T2 is the shortest. Closing time T6 is shorter than closing time T8 and longer than closing time T4. Closing time T4 is shorter than closing time T6 and longer than closing time T2. The specific times for closing times T2, T4, T6, and T8 are not particularly limited, but, by way of example, closing time T2 is 10 seconds, closing time T4 is 20 seconds, closing time T6 is 30 seconds, and closing time T8 is 40 seconds.

[0046] In step SB1, the control unit 6 acquires the pressure P of the compressed air in the buffer tank 2 based on the measurement signal output from the pressure measurement unit 5. After acquiring the pressure P, the process proceeds to step SB2. In step SB2, the control unit 6 executes a first determination process to determine whether the pressure P of the compressed air measured by the pressure measurement unit 5 is equal to or less than the set pressure A (first set pressure). If the determination in step SB2 is YES, meaning that the pressure P of the compressed air measured by the pressure measurement unit 5 is equal to or less than the set pressure A, the process proceeds to step SB3. In step SB3, the first solenoid valve 41, which is in a closed state, is opened for the open time T1, and then switched to the closed state until the close time T2 has elapsed, at which point the first solenoid valve control is terminated. When the first solenoid valve 41 is opened, the second to fifth solenoid valves 42 to 45 remain closed, thereby suppressing a sudden drop in the pressure of the compressed air in the buffer tank 2. Note that even when the second to fifth solenoid valves 42 to 45 are opened, the other solenoid valves are closed.

[0047] FIG. 5 is a graph showing the relationship between time and the pressure P of compressed air in the buffer tank 2. T10 is before the first solenoid valve 41 is opened, and at this time the pressure P is equal to or lower than the set pressure A. T11 is when the first solenoid valve 41 is opened, and opening the first solenoid valve 41 reduces the pressure P. After the open time T1 has elapsed, the first solenoid valve 41 is closed, and at T12 the pressure P recovers. The time from T11 to T12 is called the pressure recovery time. The pressure recovery time is sufficiently shorter than the closing time T2. In other words, the closing times T2, T4, T6, and T8 can be set taking the pressure recovery time into consideration and are set to be sufficiently longer than the pressure recovery time.

[0048] 4, if the determination is NO and the process proceeds to step SB4, the control unit 6 executes a second determination process to determine whether the pressure P of the compressed air measured by the pressure measurement unit 5 is higher than the set pressure A and equal to or lower than the set pressure B. If the determination is YES in step SB4, that is, if it is determined that the pressure P of the compressed air measured by the pressure measurement unit 5 is higher than the set pressure A and equal to or lower than the set pressure B, the process proceeds to step SB5. In step SB5, the first solenoid valve 41, which is in the closed state, is opened for the open time T3, and then switched to the closed state and waits until the close time T4 has elapsed, after which the first solenoid valve control is terminated.

[0049] If the determination in step SB4 is NO and the process proceeds to step SB6, the control unit 6 executes a third determination process to determine whether the compressed air pressure P measured by the pressure measurement unit 5 is higher than the set pressure B and equal to or lower than the set pressure C. If the determination in step SB6 is YES and it is determined that the compressed air pressure P measured by the pressure measurement unit 5 is higher than the set pressure B and equal to or lower than the set pressure C, the process proceeds to step SB7. In step SB7, the first solenoid valve 41, which is in the closed state, is opened for the open time T5, and then switched to the closed state and waits until the close time T6 has elapsed, ending first solenoid valve control.

[0050] If the result of the judgment in step SB6 is NO and the process proceeds to step SB8, the first solenoid valve 41, which is in the closed state, is opened for the open time T7, then switched to the closed state and waits until the close time T8 has elapsed, and the first solenoid valve control is terminated.

[0051] In this way, when it is determined that the pressure P of the compressed air is equal to or lower than the set pressure A, for example, the control unit 6 controls the first solenoid valve 41 so that the open time is longer than when the pressure P of the compressed air is higher than the set pressure A. Furthermore, when it is determined that the pressure of the compressed air P is equal to or lower than the set pressure A, the control unit 6 controls the first solenoid valve 41 so that the closed time is shorter than when the pressure P of the compressed air is higher than the set pressure A.

[0052] Similarly, when it is determined that the compressed air pressure P is equal to or lower than the set pressure B, for example, the control unit 6 controls the first solenoid valve 41 so that the open time is longer than when the compressed air pressure P is higher than the set pressure B. Furthermore, when it is determined that the compressed air pressure P is equal to or lower than the set pressure B, the control unit 6 controls the first solenoid valve 41 so that the closed time is shorter than when the compressed air pressure P is higher than the set pressure B.

[0053] Similarly, when it is determined that the compressed air pressure P is equal to or lower than the set pressure C, for example, the control unit 6 controls the first solenoid valve 41 so that the open time is longer than when the compressed air pressure P is higher than the set pressure C. Furthermore, when it is determined that the compressed air pressure P is equal to or lower than the set pressure C, the control unit 6 controls the first solenoid valve 41 so that the closed time is shorter than when the compressed air pressure P is higher than the set pressure C.

[0054] 3 is completed in this manner, the process proceeds to step SA2, where the same control as in the flowchart shown in Fig. 4 is executed for the second solenoid valve 42. In this manner, similar control is executed sequentially for the third solenoid valve 43, the fourth solenoid valve 44, and the fifth solenoid valve 45. For example, if the open time is T1 and the close time is T2 in all of the controls for the first to fifth solenoid valves 41 to 45, and the control of the first to fifth solenoid valves 41 to 45 is considered to be one cycle, the time for one cycle is calculated as T1 x 5 + T2 x 5.

[0055] As described above, in this embodiment, by opening the first solenoid valve 41, the compressed air supplied from the compressor 300 and stored in the buffer tank 2 flows through the first downstream pipe section 31 of the air piping 3 and is injected from the first injection port 31a onto the first row of filters 200. At this time, the direction in which the compressed air is injected into the filters 200 is opposite to the inflow direction of the fluid to be filtered, so that back pressure cleaning of the filters 200 becomes possible.

[0056] When the pressure of the compressed air in the buffer tank 2 is sufficiently high (higher than the set pressure C), the time T7 during which the first solenoid valve 41 is open is set short so that the minimum amount of spray is sprayed to maintain the cleaning effect of the filter 200, thereby preventing compressed air from being sprayed unnecessarily and avoiding unnecessary air consumption (step SB8).

[0057] On the other hand, if the pressure of the compressed air in the buffer tank 2 temporarily drops and falls below the set pressure A, as in step SB3, the control unit 6 controls the first solenoid valve 41 to lengthen the open time T1, thereby increasing the amount of compressed air injected toward the filter 200. This makes it possible to compensate for the drop in compressed air pressure with the amount of compressed air injected, thereby maintaining the backpressure cleaning effect.

[0058] Furthermore, when the control unit 6 determines that the pressure of the compressed air is, for example, equal to or lower than the set pressure A, it applies a shorter closing time T2 than when the pressure of the compressed air is higher than the set pressure A, thereby shortening the time interval until the first solenoid valve 41, which is in the closed state, is next switched to the open state. The same applies when it is determined that the pressure of the compressed air is equal to or lower than the set pressure B and when it is determined that the pressure of the compressed air is equal to or lower than the set pressure C.

[0059] The above-described embodiment is merely illustrative in all respects and should not be construed as limiting. Furthermore, all modifications and variations within the scope of the claims are within the scope of the present invention. The control unit 6 may control the solenoid valves 41-45, for example, using only the set pressure A, or only the set pressures A and B. When controlling using only the set pressure A, the determinations in steps SB4 and SB6 are omitted. When controlling using only the set pressures A and B, the determination in step SB6 is omitted. Alternatively, the closing times T2, T4, T6, and T8 may be the same, and only the opening times T1, T3, T5, and T7 may be varied. The present invention can also be applied when other devices 302 and 303 are not connected. [Industrial Applicability]

[0060] As described above, the present disclosure can be used when a filter of a dust collector is back-pressure cleaned with air. [Explanation of symbols]

[0061] 1. Dust collector back pressure cleaning device 2 buffer tanks 3 Air piping 31 1st downstream pipe section 31a 1st injection port 32 2nd downstream pipe section 32a 2nd injection port 4. Solenoid valve 41 First solenoid valve 42 Second solenoid valve 5 Pressure measurement section 6 Control Unit 200 filters 300 Compressor

Claims

1. A back pressure cleaning device for a dust collector that back pressure cleans a filter provided in the dust collector with compressed air, a buffer tank for storing compressed air supplied from the compressor; an air pipe connected to the buffer tank and having an injection port formed therein for injecting compressed air in the buffer tank toward the filter in a direction opposite to the inflow direction of the fluid to be filtered; a solenoid valve for opening and closing the air pipe; a pressure measuring unit that measures the pressure of the compressed air in the buffer tank; a control unit that determines whether the pressure of the compressed air measured by the pressure measuring unit is equal to or lower than a predetermined value, and that controls the solenoid valve so that the open time is longer when the pressure of the compressed air is higher than the predetermined value if it is determined that the pressure of the compressed air is equal to or lower than the predetermined value.

2. The back pressure cleaning device for a dust collector according to claim 1, When the control unit determines that the pressure of the compressed air measured by the pressure measuring unit is equal to or lower than a predetermined value, the control unit controls the solenoid valve so that the closing time is shorter than when the pressure of the compressed air is higher than the predetermined value.

3. The back pressure cleaning device for a dust collector according to claim 1, The control unit repeatedly switches the solenoid valve between open and closed states, and when it is determined that the pressure of the compressed air measured by the pressure measuring unit is equal to or lower than a predetermined value, the control unit shortens the time interval for switching the solenoid valve from a closed state to an open state compared to when the pressure of the compressed air is higher than the predetermined value.

4. The back pressure cleaning device for a dust collector according to claim 1, The control unit executes a first determination process to determine whether the pressure of the compressed air measured by the pressure measuring unit is equal to or lower than a first predetermined value, a second determination process to determine whether the pressure is higher than the first predetermined value and equal to or lower than a second predetermined value, and a third determination process to determine whether the pressure is higher than the second predetermined value.When the first determination process determines that the pressure of the compressed air is equal to or lower than the first predetermined value, the control unit controls the solenoid valve so that the open time is longer than when the second determination process determines that the pressure of the compressed air is higher than the first predetermined value and equal to or lower than the second predetermined value, and when the third determination process determines that the pressure of the compressed air is higher than the second predetermined value.

5. The back pressure cleaning device for a dust collector according to claim 1, the air piping is formed to extend in a column direction of the plurality of filters arranged in a matrix, and has a downstream pipe portion in which a plurality of the injection ports are formed corresponding to the plurality of filters arranged in the column direction, the downstream pipe section includes a first downstream pipe section and a second downstream pipe section that are arranged in parallel in a row direction of the plurality of filters arranged in the matrix, the solenoid valve includes a first solenoid valve that opens and closes the first downstream pipe portion and a second solenoid valve that opens and closes the second downstream pipe portion, The control unit controls the first solenoid valve and the second solenoid valve individually.

6. The back pressure cleaning device for a dust collector according to claim 5, The control unit opens the second solenoid valve when the first solenoid valve is closed, and opens the first solenoid valve when the second solenoid valve is closed.

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