Weighing system

Abstract

To provide a weighing system with which it is possible to suppress the influence on measuring the weight of an object to be weighed that is in a weighing tank, due to the air sprayed by a spray unit.SOLUTION: A weighing system 1 comprises: a weighing device 2 that has a weighing hopper 6 and a load detection unit 8 that detects a load corresponding to the weight of an object F to be weighed that is supplied to the inside of the weighing hopper 6; a bag filter 4 that has a filter 4c that draws in, from a first internal space A1 and a second internal space A2, and filters the air that includes the object F to be weighed, and a spray unit 4d that sprays air for removing the object F to be weighed that has accumulated in the filter 4c; and a control unit that limits the spraying of air by the spray unit 4d when the weight of the object F to be weighed is being weighed on the basis of the detection value of the load detection unit 8.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a weighing system capable of weighing the weight of granular materials such as rice and wheat flour.

Background Art

[0002] Conventionally, a dust collector for collecting dust generated in flour processing equipment (for example, a roll flour mill, a weighing device) such as a flour mill has been known. For example, the dust collector disclosed in Patent Document 1 is connected to a plurality of flour processing equipment via a centralized pipe, and the dust generated in each flour processing equipment is collected together by a large dust collector.

[0003] In addition, since dust gradually accumulates on a filter such as a filter cloth when the dust collector is continuously used, it is required to periodically remove the accumulated dust. Generally, the dust is removed by applying air jetted from an injection part such as an injection nozzle to the filter to blow off the dust from the filter.

[0004] By the way, for example, in a flour mill, in the process of milling wheat into wheat flour, weighing of intermediate products and the like is performed by a weighing device. The weighing device is equipped with a weighing tank supported by a main body frame part, and the weight of the object to be weighed supplied to the weighing tank is weighed by a load detection part such as a load cell that supports the weighing tank from below. Further, when the object to be weighed is supplied into the weighing tank, due to the impact, the object to be weighed jumps up in the weighing device and becomes flying dust, so a dust collector for collecting dust is connected to the weighing device.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Incidentally, the spray unit of the dust collector is designed to spray air at a predetermined interval, so the timing of the air spray may overlap with the timing when the load detection unit weighs the object in the weighing tank. When the weighing timing and the air spray timing overlap, the air sprayed from the spray unit can act as a shock wave on the weighing tank, causing it to vibrate or worsening the vibration. In this case, since the weighing tank is supported by the load detection unit, the vibration of the weighing tank may cause the detected value of the load detection unit to fluctuate, potentially affecting the weighing of the object based on the load detection unit.

[0007] The present invention has been made in view of the above, and its objective is to provide a weighing system that can suppress the influence of the air injected by the injection unit on the weighing of the object to be weighed in the weighing tank. [Means for solving the problem]

[0008] To achieve the above objective, the present invention is characterized in that the injection of air by the injection unit is restricted while weighing the weight of the object to be weighed supplied to the weighing tank based on the detected value of the load detection unit.

[0009] Specifically, the subject is a weighing system comprising: a weighing device having a weighing tank and a load detection unit that detects a load corresponding to the weight of the object to be weighed supplied into the weighing tank; a dust collection device having a filter that sucks in and filters air containing the object to be weighed from the internal space of the weighing device and an injection unit that injects air to remove the object accumulated on the filter, and the following solutions were implemented.

[0010] In other words, the first invention is characterized by having a limiting unit that limits the injection of air by the injection unit when the weight of the object to be weighed is being measured based on the detected value of the load detection unit.

[0011] The second invention is characterized in that, in the first invention, after supplying the object to be weighed to the weighing tank, a weight weighing unit is provided that weighs the object to be weighed in the weighing tank based on the value detected by the load detection unit, and the limiting unit limits the injection of air by the injection unit when the weight weighing unit is weighing the object to be weighed.

[0012] The third invention is characterized in that, in the second invention, the weighing device comprises a tank disposed above the weighing device and capable of storing the object to be weighed, a supply gate disposed below the tank and capable of discharging the object to be weighed from the tank toward the weighing tank which opens upward, and a supply gate control unit which controls the supply gate to be open when supplying the object to be weighed to the weighing tank, and controls the supply gate to be closed when the weight weighing unit weighs the object to be weighed in the weighing tank based on the value detected by the load detection unit, wherein the limiting unit does not limit the injection of air by the injection unit when the supply gate is open, but does limit the injection of air by the injection unit when the supply gate is closed.

[0013] The fourth invention is characterized in that, in the third invention, a communication passage is provided to connect the internal space of the weighing device and the internal space of the tank, a filtration chamber is provided inside the dust collector, the filtration chamber is connected to the internal space of the tank so as to draw in air containing the object to be weighed from the internal space of the tank and to discharge the object to be weighed recovered in the filtration chamber into the internal space of the tank.

[0014] The fifth invention is characterized in that, in the fourth invention, the dust collector is attached to the upper surface of the tank.

[0015] The sixth invention is characterized in that, in the fourth invention, only one measuring device is provided.

[0016] The seventh invention is characterized in that, in any one of the second to sixth inventions, an empty weight weighing unit is provided that weighs the empty weight of the weighing tank after the object to be weighed has been discharged based on the value detected by the load detection unit, and the limiting unit limits the injection of air by the injection unit when the empty weight weighing unit is weighing the empty weight.

[0017] The eighth invention is characterized in that, in the seventh invention, a discharge gate disposed at the bottom of the weighing tank and capable of discharging the weighed object from the weighing tank, and a discharge gate control unit which controls the discharge gate to be open when discharging the weighed object from the weighing tank, and controls the discharge gate to be closed when the empty weight weighing unit weighs the empty weight of the weighing tank based on the detected value of the load detection unit, wherein the limiting unit does not restrict the injection of air by the injection unit when the discharge gate is open, but restricts the injection of air by the injection unit when the discharge gate is closed. [Effects of the Invention]

[0018] In the first invention, when the weight of the object to be weighed in the weighing tank is being measured based on the value detected by the load detection unit, the limiting unit restricts the injection of dust removal air from the injection unit. This suppresses the vibration of the weighing tank caused by the shock waves generated by the air, thereby reducing the influence on the measurement of the weight of the object to be weighed in the weighing tank.

[0019] In the second invention, after supplying the object to be weighed to the weighing tank, when the weighing unit weighs the object based on the detected value of the load detection unit, the limiting unit restricts the injection of air from the injection unit. This prevents the shock waves generated by the air injected from the injection unit from acting on the weighing tank, which is vibrating due to the impact when the object is supplied, which would further worsen the vibration of the weighing tank and cause the detected value of the load detection unit to become unstable. Therefore, for example, when the weighing unit determines the detected value of the load detection unit at a predetermined time after the start of weighing as the weighed value, the restriction of air injection makes it easier for the detected value at the predetermined time to stabilize, thus suppressing weighing errors. Also, for example, when the weighing unit determines the detected value of the load detection unit at the point when it has settled within a predetermined range of fluctuation as the weighed value, the restriction of air injection causes the detected value to settle within the predetermined range of fluctuation earlier, thus preventing the weighing time by the weighing unit from becoming too long.

[0020] In the third invention, when the supply gate is opened to supply an object to be weighed into the weighing tank, air is injected from the injection unit in accordance with the open state of the supply gate. Conversely, when the supply gate is closed to weigh the object in the weighing tank, the injection of air from the injection unit is restricted in accordance with the closed state of the supply gate. In other words, the state in which the injection of air from the injection unit is restricted and the state in which it is not restricted can be switched depending on the open or closed state of the supply gate, thereby preventing the control system and control processing of the restriction unit from becoming overly complex.

[0021] In the fourth invention, when the dust collection unit is operated, air containing dust generated in the internal space of the weighing device, such as in the weighing tank, is drawn into the filtration chamber of the dust collection unit via the connecting passage and the internal space of the tank. The material to be weighed contained in the air drawn into the filtration chamber is separated from the air by the filter and recovered, and then discharged directly into the internal space of the tank. This makes it possible to return the material to be weighed recovered by the dust collection unit to the tank, thereby suppressing a deterioration in yield.

[0022] In the fifth invention, when the air jetted from the jetting unit hits the filter, the metered material deposited on the filter falls by gravity and is directly returned into the tank. Thereby, it becomes possible to return the metered material collected in the dust collecting unit to the tank by utilizing gravity. Therefore, since a device or the like for sending the metered material from the dust collecting unit to the tank becomes unnecessary separately, an increase in the cost of the metering system can be suppressed.

[0023] In the sixth invention, since the dust collecting unit is connected to only one metering device, the metered material collected in the dust collecting unit does not mix with other metering devices, that is, metered materials of different grades. Thereby, it becomes possible to prevent the product produced from the metered material returned from the dust collecting unit to the tank from becoming of low grade due to the mixing of metered materials of different grades.

[0024] In the seventh invention, when the tare weight measuring unit measures the tare weight of the metered material based on the detection value of the load detecting unit after discharging the metered material from the metering tank, the jetting of air from the jetting unit is restricted by the restricting unit. Thereby, for example, it is possible to prevent the vibration of the metering tank due to the rapid discharge of the metered material from the metering tank from being further deteriorated by the shock wave generated from the air and the detection value of the load detecting unit from becoming unstable. Therefore, it becomes possible to suppress the occurrence of a metering error in the tare weight and the elongation of the metering time by the tare weight measuring unit.

[0025] In the eighth invention, when the discharge gate is in the open state when discharging the metered material from the metering tank, the jetting of air from the jetting unit is executed in accordance with the open state of the discharge gate. On the other hand, when the discharge gate is in the closed state when measuring the tare weight of the metering tank, the jetting of air from the jetting unit is restricted in accordance with the closed state of the discharge gate. That is, since the state of restricting the jetting of air from the jetting unit and the state of not restricting the jetting can be switched according to the open / closed state of the discharge gate, it is possible to suppress the complication of the control system and control process of the restricting unit.

Brief Description of the Drawings

[0026] [Figure 1] It is a perspective view showing a weighing system according to an embodiment of the present invention. [Figure 2] It is a diagram showing the internal configuration of the weighing device. [Figure 3] It is a block diagram showing a control system provided in the weighing system according to an embodiment of the present invention. [Figure 4] It is a flowchart showing the first half of the control process of the control unit. [Figure 5] It is a flowchart showing the second half of the control process of the control unit. [Figure 6] It is a diagram showing a state in which the supply process is being executed. [Figure 7] It is a diagram showing a state in which the weight measurement process is being executed. [Figure 8] It is a diagram showing a state in which the discharge process is being executed. [Figure 9] It is a diagram showing a state in which the tare weight measurement process is being executed. [Figure 10] It is a timing chart according to an embodiment of the present invention. [Figure 11] It is a timing chart according to a comparative example. [Figure 12] It is a diagram corresponding to FIG. 1 according to a modified example. [Figure 13] It is a diagram corresponding to FIG. 2 according to a modified example.

Mode for Carrying Out the Invention

[0027] Hereinafter, embodiments of the present invention will be described in detail based on the drawings. Note that the following description of the preferred embodiments is merely illustrative in nature.

[0028] Figure 1 shows a weighing system 1 according to an embodiment of the present invention. The weighing system 1 is installed, for example, in the flour milling process of a flour mill and is used to weigh the weight of the material to be weighed F (for example, an intermediate product produced in the flour milling process, such as flour), which is a powder or granular material. The weighing system 1 consists of a weighing device 2, a tank 3 attached to the top of the weighing device 2, and a bag filter 4 attached to the top surface of the tank 3.

[0029] The weighing device 2 comprises a pair of main frame sections 2a. As shown in Figure 2, the main frame section 2a is roughly rectangular in shape with its centerline extending vertically, and a discharge chute section 2b having a first internal space A1 is connected to its lower end. An intake pipe section 2c branches off from the side of the discharge chute section 2b, and the intake pipe section 2c extends upward from the branching point, with an intake port 2d provided at its upper end. A damper 5, which is opened and closed by an air cylinder (not shown), is also provided in the intake pipe section 2c.

[0030] A weighing hopper 6 is positioned between a pair of main frame sections 2a and above the discharge chute section 2b. The weighing hopper 6 is cylindrical and is assembled to the main frame section 2a. An upper opening 6a is provided at the top of the weighing hopper 6, opening upwards.

[0031] Above the pair of main frame sections 2a and the weighing hopper 6, a roof section 2e is provided, to which the upper ends of the pair of main frame sections 2a are connected. The inside of the roof section 2e is connected to the inside of the weighing hopper 6 through an upper opening 6a. As a result, a second internal space A2 is formed by the internal space of the roof section 2e and the internal space of the weighing hopper 6. This second internal space A2 is connected to a first internal space A1 provided inside the discharge chute section 2b via a ventilation passage 2f provided within each of the main frame sections 2a.

[0032] Furthermore, a lower opening 6b is provided at the bottom of the weighing hopper 6, which opens downwards.

[0033] A discharge gate 7 is provided at the lower opening 6b, which allows for adjustment of the opening area of ​​the lower opening 6b. The discharge gate 7 is configured to open and close the lower opening 6b by being driven by an air cylinder (not shown). When the discharge gate 7 is closed, it becomes possible to store the weighed material F in the weighing hopper 6. On the other hand, when the discharge gate 7 is open, it becomes possible to discharge the weighed material F in the weighing hopper 6 downward toward the first internal space A1 of the discharge chute 2b.

[0034] The weighing hopper 6 is supported by a load detection unit 8. The load detection unit 8 is fixed to the main frame 2a. Thus, the weighing hopper 6 is supported by the main frame 2a via the load detection unit 8. To describe the support structure of the weighing hopper 6 in this embodiment in more detail, the weighing hopper 6 is provided with a first frame portion 6c that extends horizontally and outward from the outer surface of the weighing hopper 6, and the first frame portion 6c is mounted on the load detection unit 8. Below the load detection unit 8, a second frame portion 8a that extends horizontally is provided, and the outer end of the second frame portion 8a is fixed to the main frame 2a.

[0035] Furthermore, the load detection unit 8 (for example, a load cell) detects the load corresponding to the weight of the weighing hopper 6, that is, the weight when the object to be weighed F is supplied to the weighing hopper 6, and the weight when the object to be weighed F is discharged from the weighing hopper 6 (empty weight), and outputs a voltage signal corresponding to the detected load as a detected value. In this embodiment, since the weighing hopper 6 is mounted on the load detection unit 8, the heavier the weight of the weighing hopper 6, the greater the load acting on the load detection unit 8. The load detection unit 8 is configured to output a voltage signal that shows a higher voltage the greater the load acting on it.

[0036] Tank 3 has an upper half that is roughly rectangular in shape, while its lower half is roughly in the shape of an inverted square pyramid, and has a third internal space A3 inside. An input pipe section 3a, with a cylindrical centerline extending vertically, is attached to the center of the top surface of Tank 3, and the material to be weighed F is introduced into the third internal space A3 from the upstream process via this input pipe section 3a.

[0037] Furthermore, a supply pipe section 3b is provided at the bottom of the tank 3, with the cylindrical centerline extending vertically, and the third internal space A3 of the tank 3 is connected to the second internal space A2 of the measuring device 2 via this supply pipe section 3b.

[0038] A supply gate 9 is provided at the lower end of the supply pipe section 3b. The supply gate 9 is driven by an air cylinder (not shown) to open and close the lower opening of the supply pipe section 3b. When the supply gate 9 is closed, the material to be weighed F is stored in the third internal space A3 of the tank 3, meaning that the material to be weighed F from the third internal space A3 is not supplied to the weighing hopper 6 in the second internal space A2 via the supply pipe section 3b. On the other hand, when the supply gate 9 is open, the material to be weighed F from the third internal space A3 of the tank 3 is discharged, meaning that the material to be weighed F from the third internal space A3 is supplied to the weighing hopper 6 in the second internal space A2 via the supply pipe section 3b.

[0039] A duct 10 extending vertically is provided on the side of the tank 3. One end of the duct 10 is connected to a first opening 2g provided in the roof portion 2e, and the other end is connected to a second opening 3c provided on the upper surface of the tank 3. As a result, the second internal space A2 of the weighing device 2 and the third internal space A3 of the tank 3 are in communication via the duct 10. Furthermore, since the second internal space A2 of the weighing device 2 is in communication with the first internal space A1 via the ventilation passages 2f of each main frame portion 2a, the first internal space A1 of the weighing device 2 is in communication with the third internal space A3 of the tank 3 via the ventilation passages 2f, the second internal space A2, and the duct 10.

[0040] The bag filter 4 comprises a fan section 4a and a main body section 4b, which is attached to the lower part of the fan section 4a and has a substantially octagonal prism shape. A filtration chamber R is provided inside the main body section 4b. The filtration chamber R has an opening at its lower part and is connected to the third internal space A3 of the tank 3 through this opening.

[0041] The filtration chamber R is equipped with an external filtration filter 4c (for example, a felt filter cloth). The filter 4c is substantially cylindrical and suspended from the ceiling of the filtration chamber R with its cylindrical centerline extending in the vertical direction.

[0042] An injection unit 4d capable of injecting air (for example, pulsed air) is provided above the filter 4c. The nozzle of the injection unit 4d is directed downward so that the air injected from the nozzle can be directed onto the filter 4c.

[0043] The control system 11 provided in the weighing system 1 will be explained using Figure 3.

[0044] The control system 11 includes a control unit 12 connected to the fan unit 4a, the injection unit 4d, the damper 5, the discharge gate 7, the load detection unit 8, and the supply gate 9. In this embodiment, the control unit 12 is provided in the weighing device 2.

[0045] The control unit 12 is equipped with a processor (not shown), which is configured to perform weighing processing to calculate a weighing value by converting the detected value (voltage signal corresponding to the load) received from the load detection unit 8 into a weight value (weight of the weighing hopper 6), and to perform control processing for the fan unit 4a, injection unit 4d, damper 5, discharge gate 7, and supply gate 9.

[0046] Furthermore, the control unit 12 is equipped with a limiting unit 12a, an discharge gate control unit 12b, a supply gate control unit 12c, a weight weighing unit 12d, and an empty weight weighing unit 12e.

[0047] The limiting unit 12a is configured to switch between a state in which the injection of air from the injection unit 4d is restricted (a state in which air is not injected even when it is time to inject air) and a state in which the injection of air from the injection unit 4d is not restricted, that is, a state in which air injection is permitted (a state in which air is injected when it is time to inject air), depending on the open / closed state of the discharge gate 7 and the supply gate 9.

[0048] The discharge gate control unit 12b is configured to control the open / closed state of the discharge gate 7. The supply gate control unit 12c is configured to control the open / closed state of the supply gate 9.

[0049] The weighing unit 12d is configured to weigh the weight of the object F in the weighing hopper 6 based on the value detected by the load detection unit 8 after the object F has been supplied to the weighing hopper 6. The empty weighing unit 12e is configured to weigh the empty weight of the weighing hopper 6 after the object F has been discharged, based on the value detected by the load detection unit 8.

[0050] Next, the control process performed by the control unit 12 will be explained using Figures 4 to 11. In Figures 10 and 11, the vertical axis represents the weight of the weighing hopper 6 (detection value from the load detection unit 8), and the horizontal axis represents time.

[0051] In step S1, it is determined whether or not the metering device 2 is in operation. If the determination is Yes (metering device 2 is in operation), the process proceeds to step S2. However, if the determination is No (metering device 2 is stopped), the determination process in step S1 is repeated until the determination in step S1 becomes Yes. When the metering device 2 is stopped, as shown in Figure 2, the fan section 4a is in the OFF state, the injection section 4d is not injecting air, the damper 5 is in the open state, the discharge gate 7 is in the closed state, and the supply gate 9 is in the closed state. At this time, the fan section 4a is in the OFF state (not drawing air) and the damper 5 is in the open state, meaning that the internal space of the metering device 2 (first internal space A1 and second internal space A2) and the outside of the metering device 2 are in communication via the intake pipe section 2c, so the internal space of the metering device 2 (the first internal space A1 and second internal space A2) is at approximately atmospheric pressure.

[0052] In the supply process of step S2, as shown in Figure 6, the fan unit 4a is switched from the OFF state to the ON state, air injection by the injection unit 4d is permitted (air injection is performed when it is time to inject air), the damper 5 is switched from the open state to the closed state, the discharge gate 7 is kept in the closed state, and the supply gate 9 is controlled to switch from the closed state to the open state. As the discharge gate 7 is kept in the closed state and the supply gate 9 is switched from the closed state to the open state, the object to be weighed F in the third internal space A3 is supplied to the weighing hopper 6 in the second internal space A2 via the supply pipe unit 3b and stored in the weighing hopper 6. As a result, as shown in Figure 10, the weight (detected value) of the weighing hopper 6 detected by the load detection unit 8 increases over time.

[0053] Furthermore, in the supply process of step S2, the material to be weighed F is turned into dust by the impact of its fall when supplied from the tank 3 to the weighing hopper 6. The air in the second internal space A2 containing this dust is drawn into the filtration chamber R of the bag filter 4 by passing through the duct 10 and the third internal space A3 of the tank 3 in sequence, since the fan unit 4a is in the ON state. The drawn-in air is filtered as it passes through the filter 4c, that is, separated into clean air and dust. The clean air is then discharged to the outside from the fan unit 4a, while the dust adheres to the outer surface of the filter 4c. As the bag filter 4 continues to be used, dust will accumulate on the outer surface of the filter 4c, so the spray unit 4d is configured to periodically (for example, once every 3 minutes) spray air towards the filter 4c to remove the accumulated dust. When the sprayed air hits the filter 4c, the dust accumulated on the outer surface of the filter 4c is blown off. The dust falls from the filtration chamber R into the third internal space A3 of the tank 3, is returned to the third internal space A3, and is then supplied from the tank 3 to the metering hopper 6.

[0054] In step S3, it is determined whether the detected value of the load detection unit 8, that is, the weight of the object F to be weighed supplied to the weighing hopper 6, is equal to or greater than a first predetermined weight. If the determination is Yes (greater than or equal to the first predetermined weight), the process proceeds to step S4. If the determination is No (less than the first predetermined weight), the determination process in step S3 is repeated until the determination in step S3 becomes Yes. In this embodiment, the first predetermined weight is set to approximately 80% of the upper limit weight that the weighing hopper 6 can weigh.

[0055] In the weighing process of step S4, as shown in Figure 7, the fan unit 4a is kept in the ON state, switching from a state that allows air injection by the injection unit 4d (a state in which air injection is performed when it is time to inject air) to a state in which air injection by the injection unit 4d is prohibited by the limiting unit 12a (a state in which air injection is not performed even when it is time to inject air), the damper 5 is switched from the closed state to the open state, the discharge gate 7 is kept in the closed state, and the supply gate 9 is controlled to switch from the open state to the closed state. Even when the supply gate 9 is switched from the open state to the closed state, as shown in Figure 10, the detected value of the load detection unit 8 is not stable and fluctuates gradually, but the fluctuations become smaller over time. Also, in step S4, since the fan unit 4a is in the ON state, the pressure in the second internal space A2 fluctuates due to the suction of the fan unit 4a, which may affect the weighing of the weighing hopper 6 based on the detected value of the load detection unit 8. In contrast, in this embodiment, by switching the damper 5 from a closed state to an open state in step S4, outside air introduced into the first internal space A1 from the intake pipe section 2c is also introduced into the second internal space A2 via the ventilation passage 2f. This prevents pressure fluctuations in the second internal space A2.

[0056] In step S5, it is determined whether the fluctuation of the detected value of the load detection unit 8 is within a predetermined range. If the determination is Yes (the fluctuation of the detected value is within the predetermined range), the process proceeds to step S7; however, if the determination is No (the fluctuation of the detected value is outside the predetermined range), the process proceeds to step S6. In this embodiment, if the fluctuation range of the detected value of the load detection unit 8 remains at 10g or less for 1 second or more, it is determined that the fluctuation of the detected value has entered a stable detection range, that is, it has entered the predetermined range.

[0057] In step S6, it is determined whether a first predetermined time (for example, 2.5 seconds) has elapsed since the start of step S4. If the determination is Yes (the first predetermined time has elapsed), the process proceeds to step S7; however, if the determination is No (the first predetermined time has not elapsed), the process proceeds to step S5. In this embodiment, the determination processes in steps S5 and S6 are repeatedly executed until the determination in step S5 or step S6 is Yes.

[0058] In step S7, the weighing unit 12d sets the detected value of the load detection unit 8 at the time a "Yes" decision was made in step S5 or step S6 as the first weight. This first weight is the amount of object F to be weighed supplied from the tank 3 to the weighing hopper 6, that is, the weight of the object F in the weighing hopper 6. Here, as shown in the comparative example in Figure 11, when air is sprayed from the spray unit 4d in steps S4 to S6 (weighing process), the shock wave generated by the air acts on the weighing hopper 6 in the second internal space A2 via the filtration chamber R, the third internal space A3, and the duct 10, causing or worsening the vibration of the weighing hopper 6. As a result of this vibration, the state in which the decision in step S5 is "NO" (the state in which the fluctuation of the detected value of the load detection unit 8 is outside the predetermined range) continues until the first predetermined time in step S6 has elapsed. As a result, the unstable detected value of the load detection unit 8 at the time of the first predetermined elapsed time is set as the first weight, which may cause weighing errors. In contrast, in this embodiment, the injection of air by the injection unit 4d is prohibited in steps S4 to S6 (weighing process). Therefore, the shock waves generated by the air do not act on the weighing hopper 6 and cause or worsen the vibration of the weighing hopper 6, thereby preventing weighing errors in the first weight measured based on the detected value of the load detection unit 8.

[0059] In the discharge process of step S8 shown in Figure 5, as shown in Figure 8, the fan section 4a is kept in the ON state, the limiting section 12a switches from a state where air injection by the injection section 4d is prohibited (even when it is time to inject air, air injection is not performed) to a state where air injection is permitted (when it is time to inject air, air injection is performed), the damper 5 is switched from the open state to the closed state, the discharge gate 7 is switched from the closed state to the open state, and the supply gate 9 is controlled to be kept in the closed state. When the discharge gate 7 is switched from the closed state to the open state, the weighed object F in the weighing hopper 6 is discharged from each lower opening 6b toward the discharge gate section 2b (first internal space A1). As a result, as shown in Figure 10, the weight of the weighing hopper 6 detected by the load detection section 8 (detected value) decreases over time. Here, the object to be weighed F is turned into dust by the impact of its fall when discharged from the weighing hopper 6. This dust is then sucked into the filtration chamber R of the bag filter 4 by the fan unit 4a and collected.

[0060] In step S9, it is determined whether the detected value of the load detection unit 8, that is, the weight of the weighing hopper 6, is less than the second predetermined weight. If the determination is Yes (less than the second predetermined weight), the process proceeds to step S10. If the determination is No (greater than or equal to the second predetermined weight), the process in step S9 is repeated until the determination in step S9 becomes Yes. In this embodiment, the second predetermined weight is set to 50g.

[0061] In the empty weight weighing process of step S10, as shown in Figure 9, the fan unit 4a is kept in the ON state, switching from a state that allows air injection by the injection unit 4d (a state in which air injection is performed when it is time to inject air) to a state in which air injection by the injection unit 4d is prohibited by the limiting unit 12a (a state in which air injection is not performed even when it is time to inject air), the damper 5 is switched from the closed state to the open state, the discharge gate 7 is switched from the open state to the closed state, and the supply gate 9 is kept in the closed state. Even when the discharge gate 7 is switched from the open state to the closed state, as shown in Figure 10, the detected value of the load detection unit 8 does not stabilize and repeatedly increases and decreases gradually, but the increase and decrease become smaller over time.

[0062] In step S11, it is determined whether the fluctuation of the detected value of the load detection unit 8 is within a predetermined range. If the determination is Yes (the fluctuation of the detected value is within the predetermined range), the process proceeds to step S13. If the determination is No (the fluctuation of the detected value is outside the predetermined range), the process proceeds to step S12.

[0063] In step S12, it is determined whether a second predetermined time (for example, 1.5 seconds) has elapsed since the start of step S10. If the determination is Yes (the second predetermined time has elapsed), the process proceeds to step S13; if the determination is No (the second predetermined time has not elapsed), the process proceeds to step S11. In this embodiment, the determination processes in steps S11 and S12 are repeatedly executed until the determination in step S11 or step S12 is Yes.

[0064] In step S13, the empty weight weighing unit 12e sets the detected value of the load detection unit 8 at the time a "Yes" decision was made in step S11 or step S12 as the second weight. This second weight is the weight of the weighing hopper 6 after the weighed object F has been discharged from it, that is, the empty weight of the weighing hopper 6. Here, as shown in the comparative example in Figure 11, when air is injected from the injection unit 4d in steps S10 to S12 (empty weight weighing process), the shock wave generated by the air acts on the weighing hopper 6 in the second internal space A2 via the filtration chamber R, the third internal space A3, and the duct 10, causing or worsening the vibration of the weighing hopper 6. As a result of this vibration, the state in which the decision in step S11 is "NO" (the state in which the fluctuation of the detected value of the load detection unit 8 is outside the predetermined range) continues until the second predetermined time in step S12 has elapsed. As a result, the unstable detected value of the load detection unit 8 at the second predetermined time elapsed may be set as the second weight, potentially leading to weighing errors. In contrast, in this embodiment, the injection of air by the injection unit 4d is prohibited in steps S10 to S12 (empty weight weighing process). Therefore, the shock waves generated by the air do not act on the weighing hopper 6, preventing it from causing or worsening of vibrations, thus preventing weighing errors in the empty weight (second weight) of the weighing hopper 6, which is weighed based on the detected value of the load detection unit 8.

[0065] In step S14, the weighed value is calculated by subtracting the second weight set in step S13 from the first weight set in step S7. This weighed value corresponds to the weight measured by the weighing device 2, and excludes the weight of the weighed material F adhering to the inner surface of the weighing hopper 6, that is, the weight of the weighed material F that was not discharged in step S8 (discharge step). This prevents weighing errors from occurring even when weighing weighed material F that tends to adhere to the inner surface of the weighing hopper 6 (for example, intermediate products produced in the flour milling process, such as flour).

[0066] After step S14, proceed to the end and terminate the process. Then, start the process from the start in Figure 4.

[0067] As described above, according to this embodiment, when the weight of the object F to be weighed in the weighing hopper 6 is being weighed based on the value detected by the load detection unit 8, the limiting unit 12a restricts the injection of dust removal air from the injection unit 4d. This suppresses the vibration of the weighing hopper 6 caused by the shock waves generated by the air, thereby reducing the influence on the weighing of the object F in the weighing hopper 6.

[0068] Furthermore, after the object to be weighed is supplied to the weighing hopper 6, when the weight weighing unit 12d weighs the object F based on the detected value of the load detection unit 8, the limiting unit 12a restricts the injection of air from the injection unit 4d. This prevents the shock waves generated by the air injected from the injection unit 4d from acting on the weighing hopper 6, which is shaking due to the impact when the object F is supplied, from further worsening the shaking of the weighing hopper 6 and causing the detected value of the load detection unit 8 to become unstable. Therefore, for example, when the weight weighing unit 12d determines the detected value of the load detection unit 8 at a predetermined time after the start of weighing as the weighed value, the restriction of air injection makes it easier for the detected value at the predetermined time to stabilize, thus suppressing weighing errors. Furthermore, for example, if the detected value of the load detection unit 8 is determined as the weighed value when the weight weighing unit 12d falls within a predetermined fluctuation range, the air injection restriction causes the detected value to fall within the predetermined fluctuation range earlier, thereby preventing the weighing time by the weight weighing unit 12d from becoming excessively long.

[0069] Furthermore, when the supply gate 9 is opened to supply the object to be weighed F into the weighing hopper 6, air is injected from the injection unit 4d in accordance with the open state of the supply gate 9. Conversely, when the supply gate 9 is closed to weigh the object F in the weighing hopper 6, the injection of air from the injection unit 4d is restricted in accordance with the closed state of the supply gate 9. In other words, the state in which the injection of air from the injection unit 4d is restricted and the state in which it is not restricted can be switched depending on the open or closed state of the supply gate 9, thereby preventing the control system and control processing of the limiting unit 12a from becoming overly complex.

[0070] Furthermore, when the bag filter 4 is operated, air containing dust generated in the second internal space A2 of the weighing device 2, such as in the weighing hopper 6, is drawn into the filtration chamber R of the bag filter 4 via the duct 10 and the third internal space A3 of the tank 3. The material to be weighed F contained in the air drawn into the filtration chamber R is separated from the air by the filter 4c and recovered, and then discharged directly into the third internal space A3 of the tank 3. This makes it possible to return the material to be weighed F recovered by the bag filter 4 to the tank, thereby suppressing a deterioration in yield.

[0071] Furthermore, when the air injected from the injection unit 4d hits the filter 4c, the material to be weighed F accumulated on the filter 4c falls due to gravity and is returned directly to the tank 3. This makes it possible to return the material to be weighed F recovered by the bag filter 4 to the tank 3 using gravity. Therefore, since there is no need for separate equipment to send the material to be weighed F from the bag filter 4 to the tank 3, the cost increase of the weighing system 1 can be suppressed.

[0072] Furthermore, since the bag filter 4 is connected to only one weighing device 2, the weighed material F recovered in the bag filter 4 will not be mixed with weighed materials from other weighing devices, i.e., weighed materials of different grades. This prevents the product produced from being of a lower grade due to the mixing of weighed materials of different grades, which would result from the weighed material F being returned to the tank 3 from the bag filter 4.

[0073] Furthermore, after the object to be weighed F has been discharged from the weighing hopper 6, when the empty weight weighing unit 12e weighs the empty weight of the object to be weighed F based on the value detected by the load detection unit 8, the limiting unit 12a restricts the injection of air from the injection unit 4d. This prevents, for example, the vibration of the weighing hopper 6 caused by the rapid discharge of the object to be weighed F from the weighing hopper 6 from the weighing hopper 6 from being further exacerbated by the shock waves generated from the air, which would cause the value detected by the load detection unit 8 to become unstable. Therefore, it is possible to suppress the occurrence of empty weight weighing errors and the length of the weighing time by the empty weight weighing unit 12e.

[0074] Furthermore, when the discharge gate 7 is opened to discharge the weighed object F from the weighing hopper 6, air is injected from the injection unit 4d in accordance with the open state of the discharge gate 7. Conversely, when the discharge gate 7 is closed to weigh the empty weight of the weighing hopper 6, the injection of air from the injection unit 4d is restricted in accordance with the closed state of the discharge gate 7. In other words, the state in which the injection of air from the injection unit 4d is restricted and the state in which it is not restricted can be switched depending on the open or closed state of the discharge gate 7, thereby preventing the control system and control processing of the limiting unit 12a from becoming overly complex.

[0075] In this embodiment, the weighing system 1 was equipped with only one weighing device 2, but it may be equipped with two or more weighing devices 2.

[0076] Furthermore, although the weighing system 1 in this embodiment is equipped with a tank 3, it may be omitted.

[0077] Furthermore, although the bag filter 4 was attached to the top surface of the tank 3 in this embodiment, it may also be arranged on the side of the tank 3, as shown in Figure 12.

[0078] Furthermore, in this embodiment, the filtration chamber R of the bag filter 4 was directly connected to the third internal space A3 of the tank 3. However, as shown in Figure 12, the suction side may be connected to the third internal space of the tank 3 via the suction pipe section 4e, and the discharge side may be connected to a device other than the tank 3 via a rotary valve (not shown). This prevents, for example, when the weighing system 1 is installed in the receiving or sorting process of a flour mill, foreign matter contained in the dust collected by the bag filter 4 from being returned to the tank 3 and mixing with the weighed material F in the tank 3.

[0079] Furthermore, although this embodiment describes an example in which a bag filter 4 is used as the dust collection unit, other dust collection devices may also be used.

[0080] Furthermore, although this embodiment describes an example in which the control unit 12 is provided in the weighing device 2, the control unit may be provided in the bag filter 4, or the control unit may be provided in both the weighing device 2 and the bag filter 4. When the control unit is provided in the bag filter 4, the limiting unit provided in the control unit of the bag filter 4 may control the injection of air from the injection unit 4d. Alternatively, when the control unit is provided in both the weighing device 2 and the bag filter 4, the injection by the injection unit 4d may be limited by sending a signal from the control unit of the weighing device 2 to the control unit of the bag filter 4 instructing it to limit the injection. Alternatively, the control unit of the weighing device 2 may be provided with an exhaust gate control unit 12b, a supply gate control unit 12c, a weight weighing unit 12d, and an empty weight weighing unit 12e, while the control unit of the bag filter 4 may be provided with a limiting unit 12a.

[0081] Furthermore, although this embodiment describes an example in which the control unit 12 includes a weight weighing unit 12d and an empty weight weighing unit 12e, the control unit 12 may also be equipped with a weighing unit that has the functions of both the weight weighing unit 12d and the empty weight weighing unit 12e.

[0082] Furthermore, in this embodiment, the bag filter 4 was connected to the second internal space A2 of the weighing device 2 via the tank 3 and duct 10, but it may also be connected directly to the second internal space A2 without going through the tank 3 or duct 10.

[0083] In this embodiment, one bag filter 4 was provided, but a bag filter 4 may be provided in both the weighing device 2 and the tank 3.

[0084] Furthermore, although this embodiment describes an example in which a weighing hopper 6 is used as the weighing tank, a container other than the weighing hopper 6 may be used as long as it is capable of weighing the object F to be weighed.

[0085] Furthermore, although not provided in the weighing system 1 of this embodiment, a cleaning air duct 13 may be provided, as shown in Figure 13, with one end connected to the bag filter 4 and the other end connected to the second internal space A2 of the weighing device 2. By doing so, air can be supplied from the bag filter 4 to the inner surface of the main frame portion 2a via the cleaning air duct 13, thereby removing dust (object to be weighed F) adhering to the inner surface of the main frame portion 2a.

[0086] Furthermore, in this embodiment, in step S4 (weight weighing process) and step S10 (empty weight weighing process), the limiting unit 12a prohibited the injection of air from the injection unit 4d. However, instead of completely prohibiting the injection of air, the air injection pressure may be made lower than in step S2 (supply process) and step S8 (discharge process). Alternatively, air injection may be permitted in the first half of each process in step S4 (weight weighing process) and step S10 (empty weight weighing process) where the impact on weighing using the load detection unit 8 is relatively small, while air injection may be prohibited in the latter half of each process where the impact is relatively large. By doing so, it is possible to suppress the accumulation of dust on the filter 4c by restricting the injection of air. Therefore, it is possible to maintain the dust collection capacity of the bag filter 4 while preventing the impact on weighing using the load detection unit 8.

[0087] Furthermore, although wheat was described as an example of the material to be weighed F in this embodiment, other materials (for example, rice) may be used as the material to be weighed F. In addition, in this embodiment, the weighed value was calculated by subtracting the second weight from the first weight in step S14, but when weighing a material to be weighed F that does not easily adhere to the inner surface of the weighing hopper 6 (for example, rice), the first weight may be used as the weighed value.

[0088] Furthermore, although steps S5 and S6 in Figure 4 were performed in this embodiment, only step S6 may be performed. In this case, by setting the shortest time at which the detected value of the load detection unit 8 is predicted to stabilize (fall within a predetermined range) to the first predetermined time, the weighing time of the weighing hopper 6, that is, the weight weighing process (steps S4 and S6), can be shortened.

[0089] Furthermore, in this embodiment, the control unit 12 performed control processing using the detected value from the load detection unit 8, but it is also possible to perform control processing using a value obtained by annealing the detected value. [Industrial applicability]

[0090] This invention is suitable for a weighing system capable of measuring the weight of powders and granules such as rice and wheat flour. [Explanation of Symbols]

[0091] 1. Weighing System 2 Weighing device 3 tanks 4. Bag filter (dust collector) 4c filter 4d injection part 6. Weighing hopper (weighing tank) 7. Discharge Gate 8. Load detection unit 9 Supply Gate 10. Ducts (connecting passages) 12a Restriction section 12b Discharge gate control unit 12c Supply gate control unit 12d Weighing section 12e Empty weighing section A1 First internal space (internal space of the weighing device) A2 Second internal space (internal space of the weighing device) A3 Third internal space (internal space of the tank) R filtration chamber

Claims

1. A weighing device having a weighing tank and a load detection unit that detects a load corresponding to the weight of the object to be weighed supplied into the weighing tank, A weighing system comprising a dust collector having a filter that draws in air containing the object to be weighed from the internal space of the weighing device and filters it, and an injection unit that injects air to remove the object to be weighed accumulated on the filter, A weighing system characterized by having a limiting unit that limits the injection of air by the injection unit when weighing the weight of the object to be weighed based on the detected value of the load detection unit.

2. In the weighing system according to claim 1, After supplying the object to be weighed to the weighing tank, the weighing unit is provided to weigh the object in the weighing tank based on the value detected by the load detection unit. The weighing system is characterized in that the limiting unit limits the injection of air by the injection unit when the weighing unit is weighing the weight of the object to be weighed.

3. In the weighing system according to claim 2, A tank is provided above the weighing device and capable of storing the object to be weighed, A supply gate is provided at the bottom of the tank and is capable of discharging the material to be measured from the tank toward the measuring tank which opens upward, The system includes a supply gate control unit that controls the supply gate to be opened when supplying the object to be weighed to the weighing tank, and controls the supply gate to be closed when the weight weighing unit weighs the object to be weighed in the weighing tank based on the value detected by the load detection unit, The metering system is characterized in that the limiting unit does not restrict the injection of air by the injection unit when the supply gate is open, but does restrict the injection of air by the injection unit when the supply gate is closed.

4. In the weighing system according to claim 3, The measuring device is provided with a connecting passage that connects the internal space of the measuring device and the internal space of the tank, A filtration chamber is provided inside the dust collector. A weighing system characterized in that the filtration chamber is connected to the internal space of the tank so as to draw in air containing the material to be weighed from the internal space of the tank and to discharge the material to be weighed recovered in the filtration chamber back into the internal space of the tank.

5. In the weighing system according to claim 4, The metering system is characterized in that the dust collector is mounted on the top surface of the tank.

6. In the weighing system according to claim 4, The weighing system is characterized in that only one weighing device is provided.

7. In the weighing system according to any one of claims 2 to 6, The system includes an empty weight weighing unit that weighs the empty weight of the weighing tank after the object to be weighed has been discharged, based on the value detected by the load detection unit. The weighing system is characterized in that the limiting unit limits the injection of air by the injection unit when the empty weight weighing unit is weighing the empty weight.

8. In the weighing system according to claim 7, A discharge gate is provided at the bottom of the weighing tank and capable of discharging the weighed object from the weighing tank, The system includes a discharge gate control unit that controls the discharge gate to be opened when the object to be weighed is discharged from the weighing tank, and controls the discharge gate to be closed when the empty weight weighing unit weighs the empty weight of the weighing tank based on the value detected by the load detection unit, The metering system is characterized in that the limiting unit does not restrict the injection of air by the injection unit when the discharge gate is open, but restricts the injection of air by the injection unit when the discharge gate is closed.

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