Measuring device

Abstract

To improve throughput of a measuring device.SOLUTION: A measuring device comprises: a storage tank for storing an object to be measured, the storage tank having an opening formed in its lower part; a supply gate for opening and closing the opening; a measurement tank that is provided below the storage tank for storing the object to be measured supplied from the storage tank through the opening; a load cell configured to support the measurement tank and output a weight signal representing a weight of the object to be measured inside the measurement tank; and a controller that controls an operation of the measurement device. A locus of movement of an undersurface of the supply gate during opening and closing operations of the supply gate is set to be located inside the measurement tank in at least an area immediately below the opening. The controller is configured to control the operation of the measuring device to detect a first time point that is a time point at which a flow rate of the object to be measured supplied from the storage tank to the measurement tank is reduced by a predetermined degree, close the supply gate after the first time point, and subsequently perform measurement with the load cell.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a metering device. [Background technology]

[0002] Conventionally, there is known a weighing device that supplies objects to be weighed (e.g., grains) stored in a storage tank to a weighing tank arranged below the storage tank and weighs them using a load cell. In this type of weighing device, the objects to be weighed in the storage tank are supplied to the weighing tank by falling due to gravity when a supply gate arranged below the storage tank is opened. In such a weighing device, vibrations are generated by the impact when the objects to be weighed fall into the weighing tank. Since this vibration reduces the weighing accuracy, measurement is usually performed after waiting until the vibrations have attenuated. However, if this waiting time (the waiting time from closing the supply gate to starting measurement, hereinafter also referred to as the measurement waiting time) is long, the time required for one weighing cycle will be long, which will result in a reduction in the processing capacity of the weighing device (e.g., processing volume per hour).

[0003] For this reason, a weighing device capable of reducing the measurement waiting time has been developed. For example, the weighing device disclosed in the following Patent Document 1 performs a weighing process in the following procedure. First, when a level meter detects that a predetermined amount of objects to be weighed (an amount that can fill the metering tank) is stored in the storage tank, the supply gate is opened. Next, when the objects to be weighed in the metering tank are filled to capacity and the objects to be weighed in the storage tank and the objects to be weighed in the metering tank are continuous with each other, the supply gate is closed. Then, the load cell performs weighing. In this weighing device, before the supply gate is closed, the objects to be weighed in the metering tank (and thus the metering tank) are pressed down by the weight of the objects to be weighed in the storage tank that is continuous with the objects to be weighed in the metering tank. Therefore, the vibration of the metering tank that occurs when the objects to be weighed are supplied from the storage tank to the metering tank can be attenuated early. Therefore, the measurement waiting time from closing the supply gate to performing weighing can be reduced. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-141655 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the weighing device of Patent Document 1 has room for improvement in terms of processing capacity. Specifically, although the measurement standby time can be reduced, if the timing to close the supply gate (in other words, the timing to determine that the objects to be weighed in the weighing tank are filled to capacity) is determined by timer control, it takes a relatively long time from opening to closing the supply gate. More specifically, if the standby time from opening to closing the supply gate (hereinafter also referred to as the closing standby time) is set short, there is a risk that the supply gate will be closed before the objects to be weighed in the storage tank and the objects to be weighed in the weighing tank are continuous. If such an event occurs, the vibration will not be sufficiently attenuated, and the weighing accuracy will deteriorate. Alternatively, the measurement standby time until the vibration is attenuated will be long, and the processing capacity will decrease. On the other hand, if the closing standby time is set long enough to prevent such an event from occurring, the timing to close the supply gate will be delayed more than necessary, resulting in a decrease in processing capacity. Moreover, the supply speed (hereinafter referred to as the flow rate) of the material to be measured from the storage tank to the metering tank varies depending on the raw material conditions (e.g., type of raw material, moisture, friction, etc.), making it difficult to preset an appropriate closed standby time for all raw material conditions. [Means for solving the problem]

[0006] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized, for example, in the following forms.

[0007] According to a first aspect of the present invention, there is provided a weighing device. The weighing device includes a storage tank for storing objects to be weighed, the storage tank having an opening formed at the bottom, a supply gate for opening and closing the opening, a weighing tank provided below the storage tank for storing objects to be weighed supplied from the storage tank through the opening, a load cell configured to support the weighing tank and output a weight signal representing the weight of the objects to be weighed in the weighing tank, and a controller for controlling the operation of the weighing device. The movement trajectory of the lower surface of the supply gate during the opening and closing operation of the supply gate is set so that at least the area directly below the opening is located inside the weighing tank. The controller is configured to detect a first time point, which is a time point at which the flow rate of the objects to be weighed supplied from the storage tank to the weighing tank decreases to a predetermined extent, and to control the operation of the weighing device so as to close the supply gate after the first time point and then perform weighing using the load cell.

[0008] The "first time point", which is the time point when the flow rate of the objects to be weighed decreases to a predetermined degree, essentially means the time point when the objects to be weighed in the storage tank and the objects to be weighed in the metering tank start to be continuous with each other, in other words, the time point when the opening of the storage tank starts to be partially blocked by the objects to be weighed. When the opening of the storage tank is partially blocked, the cross-sectional area through which the objects can fall from the storage tank into the metering tank decreases, and the flow rate of the objects to be weighed drops significantly. The first time point may be detected by a direct method of monitoring the flow rate. However, the first time point may also be detected by monitoring the accumulation of the objects to be weighed near the opening of the storage tank using a level meter or a camera. In other words, the time point when it is detected using a level meter or a camera that the objects to be weighed in the storage tank and the objects to be weighed in the metering tank start to be continuous with each other may be detected as the first time point.

[0009] According to this weighing device, the first time point, i.e., the time point when the objects to be weighed in the storage tank and the objects to be weighed in the metering tank start to be continuous, is detected, and the supply gate is closed thereafter, so that the occurrence of an event in which the supply gate is closed before the objects to be weighed in the storage tank and the objects to be weighed in the metering tank become continuous can be suppressed. As a result, a decrease in weighing accuracy can be suppressed. Alternatively, a decrease in processing capacity caused by a long measurement waiting time can be suppressed. Furthermore, since the first time point is actually detected, there is no need to set a closing waiting time that is longer than necessary. Therefore, it is possible to eliminate unnecessary waiting time and improve processing capacity. Furthermore, since the first time point is actually detected, the supply gate can be closed at an appropriate timing even if a change occurs in the raw material conditions.

[0010] According to a second embodiment of the present invention, there is provided a weighing device. The weighing device includes a storage tank for storing the objects to be weighed, the storage tank having an opening formed at the bottom, a supply gate for opening and closing the opening, a weighing tank provided below the storage tank for storing the objects to be weighed supplied from the storage tank through the opening, a load cell configured to support the weighing tank and output a weight signal representing the weight of the objects to be weighed in the weighing tank, and a controller for controlling the operation of the weighing device. The movement trajectory of the lower surface of the supply gate during the opening and closing operation of the supply gate is set so that at least the area directly below the opening is located inside the weighing tank. The controller is configured to detect a first time point, which is the time point when the opening begins to be blocked by the objects to be weighed, close the supply gate after the first time point, and control the operation of the weighing device so as to perform weighing using the load cell thereafter. According to this weighing device, the same effects as those of the first embodiment can be obtained.

[0011] According to the third aspect of the present invention, in the first or second aspect, the controller is configured to calculate the flow rate of the object to be weighed based on the weight signal, and is configured to detect the time when a first condition based on at least the calculated flow rate is satisfied as the first time point. According to this aspect, the first time point can be detected using an output signal from a load cell that the weighing device originally has, so no additional device (e.g., a level meter or a camera) is required to detect the first time point. Therefore, the structure of the weighing device can be simplified and the cost can be reduced. The first condition "based on the calculated flow rate" may be a condition related to the calculated flow rate itself, or a condition related to other parameters calculated from the calculated flow rate, or both.

[0012] According to a fourth aspect of the present invention, in the third aspect, the first condition includes that the flow rate is a positive value, the rate of change of the flow rate is a negative value, and the absolute value of the rate of change is equal to or greater than a first threshold value. According to this aspect, the first point in time can be easily and accurately detected.

[0013] According to the fifth aspect of the present invention, in the third or fourth aspect, the first condition includes that the weight of the objects to be weighed represented by the weight signal is equal to or greater than the second threshold value. If the supply gate is opened when the storage tank does not contain a sufficient amount of objects to be weighed (an amount that can fill the metering tank to capacity), an event (hereinafter referred to as a shortage event) may occur in which the flow rate drops suddenly and becomes zero before the opening of the storage tank begins to be partially blocked, while the opening is not partially blocked. If such an event occurs, the first time point may be detected even though the opening of the storage tank is not partially blocked. Such unintended detection of the first time point (hereinafter also referred to as erroneous detection) can be suppressed by providing a level meter in the storage tank and setting one of the conditions for opening the supply gate as being that the objects to be weighed are stored in the storage tank in a predetermined amount or more. Alternatively, erroneous detection can be suppressed by providing a level meter in the metering tank and setting one of the first conditions as being that the storage level in the metering tank is equal to or greater than the threshold value. On the other hand, according to this embodiment, for example, if the weight at the time when the opening of the storage tank starts to be partially blocked is experimentally predicted in advance and the weight is set as the second threshold value, false detection can be suppressed without providing a level meter in the storage tank or the measuring tank. Therefore, the device configuration can be simplified and the cost can be reduced.

[0014] According to a sixth aspect of the present invention, in the fifth aspect, the controller is configured to close the supply gate when the second condition is satisfied, even if the first time point is not detected, and then perform weighing by the load cell. The second condition includes that the current weight determined based on the weight signal is equal to or greater than the second threshold, and the flow rate is zero. When a shortage event occurs, the first time point may not be detected because the first condition that the weight of the object to be weighed represented by the weight signal is equal to or greater than the second threshold is not satisfied. In such a case, even if the object to be weighed is accumulated to equal to or greater than the second threshold by intermittent supply of the object to be weighed or continuous small amount supply, the controller cannot determine the timing to close the supply gate. Alternatively, since a maximum waiting time controlled by a timer is usually set in this type of weighing device, the supply gate is closed after waiting for the maximum waiting time. On the other hand, according to this embodiment, when the weight of the object to be weighed becomes equal to or greater than the second threshold value and the supply of the object to be weighed is stopped or the opening of the storage tank is completely blocked, the supply gate can be closed without waiting for the maximum waiting time. At this time, since the weight of the object to be weighed is equal to or greater than the second threshold value, the opening is at least partially blocked, and a vibration damping effect similar to that of the first embodiment can be obtained. Furthermore, although the load cell has a characteristic that the measured value increases as time passes, according to this embodiment, the measurement process (process to determine the weight of the object to be weighed) can be performed earlier than when waiting for the maximum waiting time, and an accurate measured value can be obtained.

[0015] According to the seventh aspect of the present invention, in any one of the first to sixth aspects, the controller is configured to be able to control the weighing device in the first mode. In the first mode, the controller determines the weight at the first time point based on the weight signal, determines the current weight based on the weight signal, calculates the blocking rate of the opening based on the blocked weight, which is a weight at the second time point when the opening is completely blocked by the object to be weighed, the weight at the first time point, and the current weight, and determines the timing to close the supply gate based on the blocking rate. According to this aspect, the supply gate can be closed at an optimal timing that can improve the processing capacity. Specifically, when the supply gate is closed at the second time point, i.e., when the opening is completely blocked, the vibration is significantly attenuated, so that the measurement waiting time can be significantly shortened. However, since the flow rate decreases after the first time point, the filling efficiency (filling amount per unit supply time) is deteriorated. For this reason, closing the supply gate at the second time point is not necessarily optimal in terms of improving the processing capacity. On the other hand, if the supply gate is closed at the first time point, i.e., when the opening starts to be partially blocked, the filling efficiency is good, but the vibration may not be sufficiently damped, and the measurement waiting time may not be significantly shortened. In other words, regarding the timing of closing the supply gate, the optimal point at which both the shortening of the measurement waiting time and the filling efficiency can be achieved often exists between the first time point and the second time point. According to this embodiment, the supply gate can be closed at such an optimal point.

[0016] According to the eighth aspect of the present invention, in the seventh aspect, the controller is configured to detect the time when the third condition is satisfied as the second time, close the supply gate after the second time, and control the weighing device in a second mode in which weighing is performed by the load cell after that. The third condition includes that the flow rate calculated based on the weight signal is zero, the rate of change of the flow rate is a negative value, and the absolute value of the rate of change is equal to or greater than a third threshold. The controller is further configured to determine and store the weight at the second time detected in the second mode based on the weight signal, and is configured to use the stored weight as the predetermined blocked weight in the first mode. According to this aspect, the blocked weight is actually measured based on the objects to be weighed, so that an appropriate blocked weight according to the raw material conditions of the objects to be weighed can be set. As a result, the control according to the seventh aspect can be performed more accurately.

[0017] According to the ninth aspect of the present invention, in the seventh or eighth aspect, the controller is configured to close the supply gate when the blockage rate reaches a fourth threshold, and to dynamically set the fourth threshold according to the amplitude of the waveform of the weight signal. Since the amplitude of the vibration superimposed on the weight signal varies depending on the raw material conditions, the appropriate period for damping the vibration due to the state in which the opening of the storage tank is partially blocked, for accurate weighing (or for minimizing the measurement waiting time), varies depending on the raw material conditions. According to this aspect, even if the raw material conditions vary, the period for damping the vibration can be set without excess or deficiency. Therefore, the processing capacity can be further improved.

[0018] According to a tenth aspect of the present invention, in any one of the first to ninth aspects, the weighing device includes a gap forming means for forming a gap between the supply gate and the objects to be weighed stored in the metering tank when the supply gate is closed with the objects to be weighed filled in the metering tank. According to this aspect, the supply gate does not come into contact with the objects to be weighed in the metering tank during weighing by the load cell, thereby improving the weighing accuracy. [Brief description of the drawings]

[0019] [Figure 1] 1 is a schematic diagram showing a schematic configuration of a weighing device according to a first embodiment of the present invention. [Diagram 2] 1 is a schematic diagram showing a state of the weighing device immediately after the supply of the objects to be weighed from the storage tank to the weighing tank is started. FIG. [Diagram 3] 1 is a schematic diagram showing a state of the weighing device at a point in time when the objects to be weighed are supplied from the storage tank to the weighing tank and the opening of the storage tank begins to be partially closed. FIG. [Figure 4] 1 is a schematic diagram showing a state of the weighing device at a point in time when an object to be weighed is supplied from a storage tank to a measuring tank and the opening of the storage tank is completely closed. FIG. [Diagram 5] FIG. 13 is a schematic diagram showing the state of the metering device when the supply gate is closed. [Figure 6] 11 is a graph showing changes in weight, flow rate, and rate of change of flow rate after a supply gate is opened. [Figure 7] 10 is a flowchart showing the flow of a weighing process in a first mode. [Figure 8] 13 is a flowchart showing a flow of a blockage start point detection process. [Figure 9] 10 is a flowchart showing the flow of a weighing process in a first mode according to a second embodiment. [Figure 10] 10 is a flowchart showing a flow of blockage starting point detection processing according to the second embodiment. [Figure 11] 13 is a flowchart showing the flow of a weighing process in a second mode according to the third embodiment. [Figure 12] 13 is a flowchart showing a flow of a blockage completion point detection process. [Figure 13] 13 is a flowchart showing the flow of a weighing process in a second mode according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] 1 is a schematic diagram showing a schematic configuration of a weighing device 20 according to a first embodiment of the present invention. In this embodiment, the weighing device 20 is a device for measuring the weight of grains. However, the weighing device 20 can be used to weigh any granular or powdery material. As shown in the figure, the weighing device 20 includes a storage tank 30, a supply gate 40, a measuring tank 50, a load cell 52, a discharge gate 60, a level meter 70, and a controller 80.

[0021] The storage tank 30 is connected to a supply line (not shown) at its upper part. The objects to be weighed 90 (hereinafter also referred to as grain 90) are continuously or intermittently supplied to the storage tank 30 from this supply line and temporarily stored in the storage tank 30. The capacity of the storage tank 30 is set to be sufficiently larger (for example, 1.5 times or more) than the capacity of the weighing tank 50 described later. An opening 31 is formed at the lower part of the storage tank 30. The storage tank 30 is formed so that the cross section of the storage tank 30 becomes gradually smaller near the opening 31 toward the opening 31. A supply gate 40 is provided near the opening 31 to open and close the opening 31. In this embodiment, the supply gate 40 is configured to pivot around a fulcrum. The supply gate 40 is operated by an arbitrary actuator (for example, an air cylinder). The supply gate 40 has an arc-shaped lower surface when viewed in a vertical cross section along the pivot direction. A protrusion 41 is provided on the lower surface of the supply gate 40 so as to protrude downward from the lower surface. More specifically, the protrusion 41 is provided on the lower surface of the supply gate 40 at the front end side in the traveling direction when the supply gate 40 is closing (in this embodiment, the front end portion in the traveling direction). In this embodiment, the supply gate 40 has a constant radius when viewed in a vertical cross section along the pivot direction, except for the portion where the protrusion 41 is provided.

[0022] Weighing tank 50 is open at the top and is located below storage tank 30. When viewed vertically, storage tank 30 is located approximately in the center of weighing tank 50. Weighing tank 50 temporarily stores objects to be weighed 90 supplied from storage tank 30 through opening 31. Opening 31 is located inside weighing tank 50. Weighing tank 50 is supported by load cell 52. Load cell 52 outputs a weight signal indicating the weight of grain 90 in storage tank 30 to controller 80.

[0023] A discharge outlet 51 is formed at the bottom of the measuring tank 50. A discharge gate 60 for opening and closing the discharge outlet 51 is provided near the discharge outlet 51. Grain 90 stored in the measuring tank 50 is weighed and then discharged to downstream equipment (e.g., a storage tank, a conveyor, etc.).

[0024] Level gauge 70 is disposed on the upper part of storage tank 30. Level gauge 70 detects whether or not a predetermined amount of grain 90 or more is stored in storage tank 30. Controller 80 includes a CPU and a memory, and controls the overall operation of weighing device 20 by the CPU executing a program stored in the memory.

[0025] In the metering device 20, the movement trajectory of the lower surface of the supply gate 40 during the opening and closing operation of the supply gate 40 is set so as to be located inside the metering tank 50 at least in the region directly below the opening 31. In FIG. 1, the movement trajectory 35 of the lower surface of the protrusion 41 formed on the supply gate 40 is shown as the trajectory of the lower surface of the supply gate 40.

[0026] When weighing is performed using the weighing device 20, grain 90 is first stored in the storage tank 30 with the supply gate 40 in the closed position. Next, when the supply gate 40 is opened, the grain 90 in the storage tank 30 falls into the weighing tank 50 by gravity. Then, after the supply gate 40 is closed, a measurement process (a process for determining the weight of the grain 90 in the weighing tank 50) is performed. When the measurement process is completed, the discharge gate 60 is opened, the grain 90 in the weighing tank 50 is discharged, and then the discharge gate 60 is closed. The weighing device 20 repeats such a cycle to sequentially perform weighing. In such a weighing device 20, when the supply gate 40 is opened, the grain 90 collides with the bottom surface of the weighing tank 50, and the metering tank 50 vibrates due to the impact force. This vibration is superimposed on the weight signal output from the load cell 52, so in order to perform an accurate measurement process, it is necessary to wait for the vibration to attenuate before performing the measurement process. The weighing device 20 has a function of efficiently damping this vibration. Such a configuration will be described below.

[0027] Fig. 2 shows the state of weighing device 20 immediately after supply gate 40 is opened and the supply of grain 90 from storage tank 30 to metering tank 50 begins. In Fig. 2, grain 90 falling from storage tank 30 to metering tank 50 is not shown, and only grain 90 stored in storage tank 30 and grain 90 that has already been piled up in metering tank 50 are shown. Opening 31 of storage tank 30 is disposed in the center of metering tank 50 when viewed in the vertical direction, so that, as shown in Fig. 2, within metering tank 50, grain 90 is piled up highest in the area directly below opening 31, and the piled up height decreases the further away from directly below opening 31.

[0028] As the supply of grain 90 progresses, the height of the grain 90 in the metering tank 50 increases, and the grain 90 in the storage tank 30 and the grain 90 accumulated in the metering tank 50 begin to be continuous with each other. Specifically, as shown in FIG. 3 (grain 90 falling is not shown), the grain 90 in the metering tank 50 is continuous with the grain 90 in the storage tank 30 only in the central region where the height of the grain 90 is the highest. In other words, the opening 31 is partially blocked. The point in time at which the opening 31 begins to be partially blocked is also called the blocking start point. When the blocking start point is reached, the cross-sectional area through which the grain 90 can fall from the storage tank 30 into the metering tank 50 decreases (more specifically, the cross-sectional area of ​​the opening 31 that is partly blocked decreases), and thereafter, the grain 90 is supplied from the storage tank 30 to the metering tank 50 only from the unblocked region of the opening 31. Hereinafter, the state in which the grain 90 in the storage tank 30 and the grain 90 piled up in the measuring tank 50 are continuous will also be referred to as a continuous state.

[0029] 3, when grain 90 in storage tank 30 and grain 90 piled up in weighing tank 50 are continuous, the weight of grain 90 in storage tank 30 presses down on grain 90 piled up in weighing tank 50, and ultimately on weighing tank 50. This makes it possible to efficiently attenuate the vibration components superimposed on the weight signal output from load cell 52.

[0030] Then, as the supply of grain 90 from storage tank 30 to metering tank 50 continues, the entire cross-sectional area of ​​opening 31 is blocked (i.e., completely blocked) as shown in Fig. 4, and the supply of grain 90 from storage tank 30 to metering tank 50 stops. The point at which opening 31 is completely blocked in this manner is also referred to as the point of complete blockage. When the point of complete blockage is reached, the amount of grain 90 in storage tank 30 that applies a downward force to the grain 90 piled up in metering tank 50 increases, further enhancing the vibration damping effect.

[0031] In the state shown in Fig. 3 or Fig. 4, when supply gate 40 pivots in the direction of arrow A1 (see Fig. 5) and is closed, the surface (upper end portion) of the objects 90 to be weighed is scraped forward in the direction of travel of supply gate 40 by protrusion 41, as shown in Fig. 5. As a result, a gap 91 is formed between supply gate 40 and objects 90 to be weighed stored in metering tank 50. In other words, protrusion 41 functions as a gap forming means. Protrusion 41 prevents contact between supply gate 40 and objects 90 to be weighed in metering tank 50 during measurement processing, thereby improving the weighing accuracy.

[0032] Incidentally, when the supply gate 40 is closed after the clogging completion point is reached, the vibration is significantly attenuated as described above, and the measurement waiting time can be significantly shortened. However, after the clogging start point, the flow rate of the grain 90 from the storage tank 30 to the weighing tank 50 decreases, and the filling efficiency (filling amount per unit supply time) decreases. For this reason, closing the supply gate 40 after the clogging completion point is not necessarily optimal in terms of improving the processing capacity. On the other hand, when the supply gate 40 is closed at the clogging start point, the flow rate does not decrease, and the filling efficiency is good. On the other hand, although the vibration attenuation effect is obtained as described above, there is a risk that the vibration attenuation is insufficient. When the vibration attenuation is insufficient, the measurement waiting time cannot be significantly shortened. In other words, regarding the timing of closing the supply gate 40, the optimal point at which both the shortening of the measurement waiting time and the filling efficiency can be achieved (in other words, the processing capacity is most improved overall) often exists between the clogging start point and the clogging completion point. In this embodiment, the weighing device 20 has a configuration that allows the supply gate 40 to be closed at such an optimal point. Hereinafter, such a configuration will be described.

[0033] In this embodiment, the controller 80 controls the operation of the weighing device 20 in the first mode to perform a weighing process of the grain 90. FIG. 7 is a flowchart showing the flow of the weighing process in the first mode. The weighing process is started with the supply gate 40 closed. When the weighing process is started, the controller 80 first determines whether or not a predetermined amount of grain 90 or more is stored in the storage tank 30 (step S110). This determination is made using the detection result by the level meter 70. The predetermined amount is set in advance so as to achieve a state in which the opening 31 of the storage tank 30 can be completely blocked (see FIG. 4).

[0034] If the result of the determination is that the predetermined amount or more of grain 90 has not been stored, the controller 80 waits until the predetermined amount or more of grain 90 has been stored (step S110: NO). On the other hand, if the predetermined amount or more of grain 90 has been stored (step S110: YES), the controller 80 opens the supply gate 40 and starts the supply of grain 90 from the storage tank 30 to the metering tank 50 (step S120).

[0035] Next, the controller 80 executes a blockage start point detection process (step S130). FIG. 8 is a flowchart showing the flow of the blockage start point detection process. In the blockage start point detection process of this embodiment, the blockage start point is detected based on the weight signal output from the load cell 52. Specifically, the blockage start point is detected based on the flow rate (mass flow rate, unit: kg / s) of the grain 90 and the rate of change of the flow rate (hereinafter referred to as the flow rate change rate, unit: kg / s 2) is detected. First, referring to FIG. 6, the transitions of the weight, flow rate, and flow rate change rate accompanying the supply of grain 90 will be described. In FIG. 6, the left vertical axis represents weight W based on the weight signal, and the right vertical axis represents flow rate F (a value obtained by first-order differentiation of weight with respect to time) and flow rate change rate A (a value obtained by second-order differentiation of weight with respect to time). In reality, vibration components are superimposed on the weight signal. The vibration components include not only the vibration caused by the collision of grain 90 with measuring tank 50 described above, but also high-frequency noise of electronic devices such as conduction noise and radiation noise. However, for simplicity, such vibration components are not shown in FIG. 6 (except for the period from time T1 to time T2 described below).

[0036] When the supply of grain 90 starts at time T1, weight W rises sharply and then falls sharply. This is because the force of the grain 90 colliding with the weighing tank 50 causes a weight greater than the actual weight to be detected, and the vibration eventually attenuates, causing the intensity of the weight signal to approach the actual weight. The period from time T1 to time T2 at which the weight stabilizes (i.e., the weight signal represents the actual weight) is, for example, about several tens of ms. After time T2, weight W increases almost linearly. Therefore, the flow rate F remains at an almost constant value (the flow rate change rate A is a value near zero). Then, at time T3, the flow rate F falls instantaneously. At this time, the flow rate F takes a value greater than zero. The flow rate change rate A falls instantaneously to a large negative value with an absolute value in accordance with the instantaneous fall of the flow rate F, and then returns to a value near zero. This change at time T3 is caused by the opening 31 of the storage tank 30 being partially blocked. Therefore, by monitoring the flow rate F and the rate of change of the flow rate A, the time point T3 can be identified as the blockage onset point P1.

[0037] After time T3, weight W increases almost linearly at a gentler rate than from time T2 to time T3. That is, after the flow rate F decreases at time T3, it remains at an almost constant value (the flow rate change rate A is close to zero). Then, at time T4, the increase in weight W stops. That is, the flow rate F becomes zero and thereafter remains at zero. As the increase in weight W stops, the flow rate change rate A momentarily takes on a large negative absolute value and then becomes zero. This change at time T4 is due to the opening 31 of the storage tank 30 being completely blocked. Therefore, by monitoring the flow rate F and the flow rate change rate A, time T4 can be identified as the blockage completion point P2.

[0038] In the blockage start point detection process, the blockage start point P1 is detected by utilizing such a principle. To this end, the controller 80 monitors the weight W, the flow rate F, and the flow rate change rate A, which exhibit the above-mentioned behavior. Specifically, the controller 80 samples the weight signal output from the load cell 52 at a predetermined sampling period. The sampling period can be set appropriately according to the required weighing accuracy. In this embodiment, the sampling period is 1 ms. In this embodiment, the controller 80 acquires a value (hereinafter also referred to as a processed value) obtained by low-pass filtering the sampled value obtained at each sampling period as the weight W. However, if the noise is large, the weight W may be acquired by further applying any known noise removal method (e.g., a digital filter, a moving average method, a least squares method) to the processed value. In addition, the controller 80 acquires a regression line by applying the least squares method to the weight W (i.e., a plurality of processed values) of the most recent predetermined period (predetermined in advance as a period capable of removing high-frequency components, for example, 20 to 50 ms), and acquires the slope of the regression line as the flow rate F at each sampling period. Moreover, the controller 80 obtains a regression line by applying the least squares method to the multiple flow rates F, and obtains the slope of the regression line for each sampling period as the flow rate change rate A. The number of flow rates F that are the basis for calculating the flow rate change rate A can be any number equal to or greater than two, and for example, the least squares method may be applied to all flow rates F obtained in a period approximately the same as the above-mentioned most recent predetermined period for calculating the weight W.

[0039] The explanation will now be returned to FIG. 8. As shown in the figure, in this process, the controller 80 first judges whether or not a predetermined condition (the flow rate F is greater than zero, the flow rate change rate A is a negative value, and the absolute value of the flow rate change rate A is equal to or greater than the first threshold value TH1) is satisfied (step S131). This judgment is made each time the flow rate F and the flow rate change rate A are calculated (i.e., for each sampling period). The condition in step S131 is a condition that is satisfied at the blockage start point P1, as is clear from the behavior of each parameter described above and shown in FIG. 6. This condition accurately reflects the behavior of each parameter shown in FIG. 6, so that the blockage start point P1 can be easily and accurately detected. The first threshold value TH1 can be set in advance by experiment or the like in order to prevent the blockage start point P1 from being erroneously detected due to fluctuations in the flow rate F and the flow rate change rate A caused by noise. By appropriately setting the first threshold value TH1, it is possible to accurately detect when the flow rate F has decreased to a predetermined level or more (a decrease that is greater than fluctuations due to noise, such as the level that may occur when the opening 31 of the storage tank 30 begins to become blocked).

[0040] The blockage start point detection process (step S130) is executed after a predetermined period of time has elapsed after the supply gate 40 is opened. This predetermined period of time is set in advance through experiments or the like so as to be longer than the period from time T1 to time T2 shown in Fig. 6. In this way, the condition of step S131 is satisfied by the initial vibration from time T1 to time T2, and the blockage start point P1 is not erroneously detected.

[0041] If the condition is not met as a result of the determination, it means that the opening 31 of the storage tank 30 is not blocked at all, and the controller 80 waits until the condition is met (step S131: NO). On the other hand, if the condition is met (step S131: YES), it means that the blockage start point P1 has been detected, and the controller 80 determines the weight W at the time when the blockage start point P1 was detected (time T3 in FIG. 6) (step S132). In this way, the blockage start point detection process ends.

[0042] 7. After detecting the blockage start point P1, the controller 80 then starts calculating the blockage rate (step S140). The blockage rate is an index value indicating the degree to which the opening 31 of the storage tank 30 is blocked, and in this embodiment, the blockage rate is calculated by the following formula (1) using the current weight W (also referred to as weight W_current), the weight W at the blockage start point P1 (also referred to as weight W_p1), and the weight W at the blockage completion point P2 (also referred to as weight W_p2). Blockage rate (%)=(W_current-W_p1) / (W_p2-W_p1)×100 ···(1)

[0043] In calculating the blocking rate, the value determined in step S132 is used for the weight W_p1. In this embodiment, a value determined in advance by an experiment or the like is used for the weight W_p2. Since the weight W_current is obtained for each sampling period, the blocking rate is also calculated for each sampling period.

[0044] Next, the controller 80 judges whether the latest blockage rate is equal to or greater than the threshold value TH4 (step S150). If the blockage rate is less than the fourth threshold value TH4 as a result of the judgment, the controller 80 waits until the blockage rate becomes equal to or greater than the threshold value TH4 (step S150: NO). On the other hand, if the blockage rate is equal to or greater than the fourth threshold value TH4 (step S150: YES), the controller 80 closes the supply gate 40 (step S160). The fourth threshold value TH4 (%) may be set to any value greater than 0 and less than 100. In this embodiment, the fourth threshold value TH4 is determined in advance by an experiment or the like, taking into consideration the closing operation speed of the supply gate 40 so that the supply gate 40 is completely closed at the above-mentioned optimum point. The controller 80 may be configured to accept an input of raw material conditions from a user via a user interface and determine the fourth threshold value TH4 according to the raw material conditions. Since the magnitude (amplitude) of the vibration caused by the grain 90 colliding with the metering tank 50 varies depending on the raw material conditions, the above-mentioned optimum point also varies depending on the raw material conditions. Therefore, if the fourth threshold value TH4 is configured to be changeable in accordance with the raw material conditions, the processing capacity can be further improved.

[0045] When the supply gate 40 is closed in this manner, the controller 80 executes a measurement process (step S170). This measurement process is a process for determining the weight of the grain 90 in the measuring tank 50 after a predetermined measurement waiting time has elapsed. The weight can be determined by any known method based on the weight signal. At that time, a digital filter, a moving average method, a least squares method, or the like may be used as a noise removal method. Although not shown in the figures, when the measurement process is completed, the controller 80 opens the discharge gate 60, discharges the grain 90, and then closes the discharge gate 60. This ends the weighing process.

[0046] According to the above-mentioned weighing device 20, the blockage start point P1 is actually detected based on the weight signal, and then the supply gate 40 is closed. In other words, the supply gate 40 is closed after it is detected that the grain 90 in the storage tank 30 and the grain 90 in the weighing tank 50 have actually started to be continuous with each other. This makes it possible to suppress the occurrence of an event in which the supply gate 40 is closed before a continuous state occurs, and vibrations are not sufficiently attenuated. As a result, it is possible to suppress a decrease in weighing accuracy or an increase in the measurement waiting time. In addition, it is not necessary to set a closing waiting time that is longer than necessary to ensure that a continuous state occurs reliably, for safety reasons. Therefore, the processing capacity of the weighing device 20 can be improved. In addition, since the blockage start point P1 is actually detected, the supply gate 40 can be closed at an appropriate timing even if a change occurs in the raw material conditions.

[0047] Furthermore, according to the weighing device 20, the flow rate F is calculated based on the weight signal, and the time when the condition based on the flow rate F (the condition in step S131 described above) is satisfied is detected as the blockage start point P1. That is, the output signal from the load cell 52 that the weighing device 20 originally has is used to detect the blockage start point P1. Therefore, no additional device (e.g., a level meter or a camera) is required to detect the blockage start point P1. This allows the structure of the weighing device 20 to be simplified and the cost to be reduced.

[0048] Furthermore, according to the weighing device 20, the timing for closing the supply gate 40 is determined based on the blocking rate. Therefore, the supply gate 40 can be closed between the blocking start point P1 and the blocking end point P2 (that is, the optimal point at which both the shortening of the measurement waiting time and the filling efficiency can be achieved).

[0049] A second embodiment of the present invention will be described below. Structurally, the weighing device 20 according to the second embodiment differs from the first embodiment only in that it does not include a level meter 70. Due to this, the contents of the weighing process in the first mode differ from those of the first embodiment. Hereinafter, the second embodiment will be described with reference to Figs. 9 and 10, focusing only on the differences from the first embodiment. In Figs. 9 and 10, the same processes as those in the first embodiment (Figs. 7 and 8) are denoted by the same reference numerals as those in the first embodiment, and detailed descriptions thereof will be omitted.

[0050] 9 is a flowchart showing the flow of the weighing process in the first mode according to the second embodiment. In the second embodiment, the weighing process is started when the grain 90 in the metering tank 50 is discharged and the discharge gate 60 is closed after the first weighing process (i.e., the first cycle of the repeatedly executed weighing cycles) and thereafter. When the weighing process is started, the controller 80 first opens the supply gate 40 to start the supply of the grain 90 from the storage tank 30 to the metering tank 50 (step S120). In the second embodiment, the level gauge 70 is not provided in the storage tank 30, so the supply gate 40 is opened regardless of the storage level of the storage tank 30.

[0051] Next, the controller 80 executes a blockage start point detection process (step S230). FIG. 10 is a flowchart showing the flow of the blockage start point detection process according to the second embodiment. In this process, the controller 80 first determines whether or not a predetermined condition (the flow rate F is greater than zero, the flow rate change rate A is a negative value, the absolute value of the flow rate change rate A is equal to or greater than the first threshold value TH1, and the weight is equal to or greater than the second threshold value TH2) is satisfied (step S231). In step S231, compared to step S131 (see FIG. 8) of the first embodiment, a condition that the weight is equal to or greater than the second threshold value TH2 (hereinafter also referred to as a weight condition) is added. The second threshold value TH2 is determined in advance by an experiment or the like as an assumed weight at the time when the opening 31 of the storage tank 30 starts to be partially blocked. The condition in step S231 is a condition that is satisfied by the blockage start point P1 (see FIG. 6).

[0052] In this embodiment, since the level gauge 70 is not provided, the continuous state does not necessarily occur when the supply gate 40 is opened. For this reason, in order to reliably determine whether or not the continuous state occurs, a weight condition is added to the conditions in step S231. If the supply gate 40 is opened when a sufficient amount of grain 90 is not stored in the storage tank 30, a shortage event may occur in which the flow rate drops suddenly to zero before the opening 31 of the storage tank 30 begins to partially block. Under the predetermined conditions in step S131, the sudden drop in the flow rate at this time may cause the blockage start point P1 to be erroneously detected. However, since the weight condition is added in step S231, such erroneous detection can be suppressed.

[0053] If the condition in step S231 is satisfied (step S231: YES), it means that the occlusion start point P1 has been detected, and the controller 80 determines the weight W at the time when the occlusion start point P1 was detected (step S132), ends the occlusion start point detection process, and proceeds to step S140 (see FIG. 9). The subsequent process is the same as in the first embodiment.

[0054] On the other hand, if the condition of step S231 is not satisfied (step S231: NO), the controller 80 judges whether or not the predetermined condition (weight is equal to or greater than the second threshold value TH2 and the flow rate is zero) is satisfied (step S233). If the judgment result shows that the predetermined condition is not satisfied (step S233: NO), the controller 80 returns the process to step S231. On the other hand, if the predetermined condition is satisfied (step S233: YES), the controller 80 advances the process to step S160 (see FIG. 9) and closes the supply gate 40.

[0055] For example, if a device that performs intermittent operation or a device that performs on / off control of operation using a level meter (e.g., a sorting device) is installed in the upstream process of the weighing device 20, even if a shortage event occurs, the supply of grain 90 to the storage tank 30 may be resumed thereafter, and a continuous state may be realized. However, if a continuous state is realized in this way, an event may occur in which the blockage start point P1 is not detected and the controller 80 cannot determine the timing to close the supply gate 40. In such a case, the supply gate 40 is closed after a timeout (elapse of the maximum waiting time) due to the timer control. On the other hand, according to step S233, the supply gate 40 can be closed in a continuous state (i.e., after the blockage start point P1) without waiting for a timeout due to the timer control. The load cell has a characteristic that the measured value increases as time passes, but according to step S233, it is possible to perform the measurement process (S170 in FIG. 9) earlier and obtain an accurate measured value, compared to a configuration in which the supply gate 40 is closed after a timeout.

[0056] According to the second embodiment described above, erroneous detection of the blockage start point P1 can be suppressed and the blockage start point P1 can be accurately detected without providing a level meter 70 in the storage tank 30. In addition, there is no need to provide a level meter or a camera in the metering tank 50 for detecting the continuous state. Therefore, the device configuration can be simplified and the cost can be reduced.

[0057] A third embodiment of the present invention will be described below. The weighing device 20 according to the third embodiment is structurally the same as that of the first embodiment. However, it differs from the first embodiment in that the controller 80 is capable of performing weighing processing in the second mode. Hereinafter, the third embodiment will be described with reference to Figs. 11 and 12, focusing only on the differences from the first embodiment. In Fig. 11, the same processes as those in the first embodiment (Fig. 7) are denoted by the same reference numerals as those in the first embodiment, and detailed descriptions thereof will be omitted.

[0058] In this embodiment, the weighing process in the second mode is performed only in the first weighing process, and in the second and subsequent weighing processes, the weighing process in the first mode is performed. However, the weighing process in the second mode may be performed periodically (for example, every time a predetermined number of weighing cycles are performed). In the first embodiment, the second mode is a process for actually measuring the weight at the occlusion completion point P2, which was previously determined by experiments or the like for use in calculating the occlusion rate.

[0059] 11 is a flowchart showing the flow of the measurement process in the second mode. When the measurement process in the second mode is started, the controller 80 first executes steps S110 and S120. When the supply gate 40 is opened in step S120, the controller 80 then executes a blockage end point detection process (step S310).

[0060] FIG. 12 is a flowchart showing the flow of the occlusion end point detection process. In this process, the occlusion completion point P2 is actually detected. Specifically, the controller 80 first judges whether or not a predetermined condition (the flow rate F is zero, the flow rate change rate A is a negative value, and the absolute value of the flow rate change rate A is equal to or greater than the third threshold value TH3) is satisfied (step S311). This judgment is made every time the flow rate F and the flow rate change rate A are calculated (i.e., every sampling period). The condition of step S311 is a condition that is satisfied at the occlusion completion point P2, as is clear from the behavior of each parameter described above and shown in FIG. 6. This condition accurately reflects the behavior of each parameter shown in FIG. 6, so that the occlusion completion point P2 can be easily and accurately detected.

[0061] If the condition is not met as a result of the determination, it means that the opening 31 of the storage tank 30 is not completely blocked, and the controller 80 waits until the condition is met (step S311: NO). On the other hand, if the condition is met (step S311: YES), it means that the blockage completion point P2 has been detected, and the controller 80 determines the weight W (W_p2) at the time when the blockage completion point P2 is detected (time T4 in FIG. 6) and stores it in the non-volatile memory (step S312). In this way, the blockage completion point detection process ends.

[0062] Now, the explanation will be returned to Fig. 11. When the occlusion completion point P2 is detected, the controller 80 then closes the supply gate 40 (step S160) and executes the measurement process (step S170). When the weighing process in the second mode is executed in this manner and the weight W_p2 is stored, the controller 80 thereafter repeatedly executes the weighing process in the first mode described above. At that time, the controller 80 uses the weight W_p2 stored in step S312 in the calculation of the blockage rate (step S140 in Fig. 7).

[0063] According to the above-described third embodiment, the weight W_p2 at the blocking completion point P2 is actually measured, so that an accurate blocking rate can be calculated in accordance with the raw material conditions of the grain 90. Therefore, in the first mode, the timing to close the supply gate 40 can be determined more accurately (i.e., so as to approach the above-described optimum point).

[0064] The fourth embodiment of the present invention will be described below. The weighing device 20 according to the fourth embodiment is structurally the same as that of the second embodiment. That is, the storage tank 30 is not provided with a level gauge 70. The fourth embodiment also differs from the second embodiment in that the controller 80 can perform weighing processing in the second mode. Hereinafter, the fourth embodiment will be described with reference to FIG. 13, focusing only on the differences from the other embodiments described above. In FIG. 13, the same processes as those in the first embodiment (FIG. 7) and the third embodiment (FIG. 11) are denoted by the same reference numerals as those in the first and third embodiments, and detailed description thereof will be omitted.

[0065] FIG. 13 is a flowchart showing the flow of the weighing process in the second mode according to the fourth embodiment. When the weighing process in the second mode is started, the controller 80 first opens the supply gate 40 (step S120), executes the blockage start point detection process, and detects the blockage start point P1 (step S230). Next, the controller 80 executes the blockage end point detection process, detects the blockage completion point P2, and stores the weight W_p2 (step S310). Next, the controller 80 closes the supply gate 40 (step S160), and executes the measurement process (step S170). After that, the controller 80 repeatedly executes the weighing process in the first mode according to the second embodiment described above. At that time, the controller 80 uses the weight W_p2 stored in step S310 in the calculation of the blockage rate (step S140 in FIG. 9).

[0066] In the third embodiment, the supply gate 40 is opened only when a predetermined amount or more of grain 90 is stored in the storage tank 30, so that the blockage completion point P2 is reliably detected, and therefore step S230 (blockage start point detection process) is omitted. On the other hand, in the present embodiment, erroneous detection of the blockage completion point P2 due to the shortage event described above may occur, so step S230 (blockage start point detection process) is set before step S310 (blockage completion point detection process) to prevent erroneous detection. In an alternative embodiment, step S230 (blockage start point detection process) is omitted, and instead, a weight condition similar to that of step S231 in FIG. 10 may be added to step S311 (see FIG. 12).

[0067] According to the above-described fourth embodiment, the weight W_p2 at the occlusion completion point P2 is actually measured, and therefore, the same effects as those of the third embodiment can be obtained.

[0068] Although the embodiment of the present invention has been described above, the above-mentioned embodiment of the invention is intended to facilitate understanding of the present invention and does not limit the present invention. The present invention may be modified or improved without departing from the spirit thereof, and the present invention includes equivalents thereof. In addition, any combination or omission of each component described in the claims and specification is possible within the scope of solving at least a part of the above-mentioned problems or achieving at least a part of the effects.

[0069] For example, the above-described flowchart is merely an example, and the order of the processes constituting the flowchart may be changed or the processes may be changed to equivalent processes without departing from the spirit of the present invention.

[0070] Furthermore, the controller 80 may dynamically set the fourth threshold value TH4 used in step S150 (see FIG. 7 and FIG. 9) according to the amplitude of the waveform of the weight signal (i.e., the amplitude of the vibration component). Specifically, the fourth threshold value TH4 may be set so that the larger the amplitude, the larger the fourth threshold value TH4 (i.e., so that the supply gate 40 is closed at a timing closer to the occlusion completion point P2). In this case, the fourth threshold value TH4 may be set to any of a plurality of predetermined numerical values ​​in stages, or may be set so that the fourth threshold value TH4 changes linearly according to the amplitude using a function. The amplitude that is the basis for dynamically setting the fourth threshold value TH4 may be detected from the weight signal before the occlusion start point P1, or may be detected from the weight signal between the occlusion start point P1 and the occlusion completion point P2. According to this configuration, even if the raw material conditions (i.e., the magnitude of vibration) vary, the vibration attenuation period required for accurate weighing (or for minimizing the measurement waiting time) can be set without excess or deficiency. Therefore, the processing capacity of the weighing device 20 can be further improved.

[0071] Furthermore, calculation of the blockage rate may be omitted. In this case, the controller 80 may close the supply gate 40 after a predetermined time has elapsed since the blockage start point P1 was detected. In this case, the predetermined time may be determined in advance by experiment or the like so that the timing of closing the supply gate 40 is between the blockage start point P1 and the blockage completion point P2. Alternatively, the controller 80 may close the supply gate 40 when the blockage start point P1 is detected. Alternatively, the controller 80 may close the supply gate 40 when the blockage completion point P2 is detected.

[0072] Furthermore, in step S131 (see FIG. 8) of the first embodiment, the blockage starting point P1 may be detected under any condition based on at least the flow rate F. For example, the blockage starting point P1 may be detected based only on the magnitude of the flow rate F. In other words, step S131 may be executed with the only predetermined condition being that the flow rate F is equal to or greater than a predetermined value.

[0073] Furthermore, the occlusion start point P1 and / or the occlusion completion point P2 are not limited to being detected based on the weight signal, and may be detected by a level meter or a camera additionally installed in the measuring tank 50.

[0074] Furthermore, the gap forming means for forming the gap 91 between the supply gate 40 and the grains 90 in the weighing tank 50 when the supply gate 40 is closed is not limited to the protrusion 41, and can be realized in any known manner. For example, the supply gate is configured to pivot about a fulcrum, and the vertical cross section of the lower surface of the supply gate along the pivot direction may be in the shape of a circular arc. In this case, the circular arc shape may be set so that the radius of the front side in the traveling direction when the supply gate is closed is larger than the radius of the rear side. In this case, when the supply gate performs the closing operation, the objects to be weighed are scraped out by the part of the supply gate on the front side in the traveling direction, so that a gap corresponding to the difference in the radii is formed. In other words, the circular arc shape of the supply gate may function as the gap forming means. Alternatively, a sliding supply gate may be used in which a protrusion that protrudes downward is formed at the front end in the traveling direction when the supply gate is closed. In this case, when the supply gate performs the closing operation, the objects to be weighed are scraped out by the protrusion, so that a gap corresponding to the height of the protrusion is formed. Alternatively, the gap creating means may be a means for blowing air along the underside of the feed gate 40 after the feed gate 40 is closed. [Explanation of symbols]

[0075] 20...Measuring device 30...Storage tank 31...Aperture 35...trajectory of movement 40...Supply gate 41...Protrusion 50...Measuring tank 51...Outlet 52...Load cell 60...Discharge gate 70...Level gauge 80...Controller 90...Object to be weighed (grain) 91...Gap

Claims

1. 1. A metering device comprising: A storage tank for storing the object to be weighed, the storage tank having an opening at a lower portion thereof; a supply gate for opening and closing the opening; a measuring tank provided below the storage tank for storing the objects to be measured supplied from the storage tank through the opening; a load cell configured to support the weighing tank and to output a weight signal representative of the weight of the object to be weighed in the weighing tank; A controller for controlling the operation of the weighing device; Equipped with a movement trajectory of a lower surface of the supply gate during an opening / closing operation of the supply gate is set so that at least a region directly below the opening is located inside the metering tank, the controller is configured to detect a first time point at which a flow rate of the object to be measured supplied from the storage tank to the measuring tank decreases to a predetermined degree, close the supply gate after the first time point, and control the operation of the measuring device so as to perform measuring using the load cell thereafter; the controller is configured to calculate a flow rate of the object to be weighed based on the weight signal, and to detect a time point at which a first condition based on at least the calculated flow rate is satisfied as the first time point; The first condition is: the flow rate is a positive value, the rate of change of the flow rate is a negative value, and the absolute value of the rate of change is equal to or greater than a first threshold value; the weight of the object to be weighed represented by the weight signal is equal to or greater than a second threshold value; Includes Weighing device.

2. 1. A metering device comprising: A storage tank for storing the object to be weighed, the storage tank having an opening at a lower portion thereof; a supply gate for opening and closing the opening; a measuring tank provided below the storage tank for storing the objects to be measured supplied from the storage tank through the opening; a load cell configured to support the weighing tank and to output a weight signal representative of the weight of the object to be weighed in the weighing tank; A controller for controlling the operation of the weighing device; Equipped with a movement trajectory of a lower surface of the supply gate during an opening / closing operation of the supply gate is set so that at least a region directly below the opening is located inside the metering tank, the controller is configured to detect a first time point at which the opening begins to be blocked by the object to be weighed, close the supply gate after the first time point, and control the operation of the weighing device so as to thereafter perform weighing using the load cell; the controller is configured to calculate a flow rate of the object to be weighed based on the weight signal, and to detect a time point at which a first condition based on at least the calculated flow rate is satisfied as the first time point; The first condition is: the flow rate is a positive value, the rate of change of the flow rate is a negative value, and the absolute value of the rate of change is equal to or greater than a first threshold value; the weight of the object to be weighed represented by the weight signal is equal to or greater than a second threshold value; Includes Weighing device.

3. A weighing device according to claim 1 or 2, the controller is configured to close the supply gate when a second condition is satisfied, even if the first time point has not been detected, and then perform weighing using the load cell; The second condition includes that a current weight determined based on the weight signal is equal to or greater than the second threshold value and the flow rate is zero. Weighing device.

4. A weighing device according to any one of claims 1 to 3, The controller is configured to control the metering device in a first mode; In the first mode, the controller: determining a weight at the first time based on the weight signal; determining a current weight based on the weight signal; calculating a blockage rate of the opening based on a blockage weight, which is a weight at a second time point when the opening is completely blocked by the object to be weighed, the weight at the first time point, and the current weight; Determining the timing to close the supply gate based on the blockage rate. Weighing device.

5. 5. A weighing device according to claim 4, the controller is configured to detect a time point when a third condition is satisfied as the second time point, close the supply gate after the second time point, and then control the weighing device in a second mode in which the weighing device performs weighing using the load cell; the third condition includes that the flow rate calculated based on the weight signal is zero, the rate of change of the flow rate is a negative value, and the absolute value of the rate of change is equal to or greater than a third threshold value; The controller further comprises: The weight at the second time point detected in the second mode is determined based on the weight signal and stored; In the first mode, the stored weight is configured to be used as the predetermined occlusion weight. Weighing device.

6. A weighing device according to claim 4 or claim 5, The controller is configured to close the feed gate when the blockage rate reaches a fourth threshold, and to dynamically set the fourth threshold in response to an amplitude of a waveform of the weight signal. Weighing device.

7. A weighing device according to any one of claims 1 to 6, a gap forming means for forming a gap between the supply gate and the object to be measured stored in the measuring tank when the supply gate is closed with the object to be measured filled in the measuring tank; Weighing device.

Images