Grain transport flow rate measurement system

Abstract

To provide a grain conveying flow rate measuring system for measuring the conveying flow rate of grain on a belt conveyor. [Solution] A grain transport flow rate measuring system comprising: an discharge adjustment means provided at a discharge port formed at the bottom of a silo for storing grain to adjust the amount of grain discharged; an unloading belt conveyor 6 positioned below the silo to transport the discharged grain; a measuring device 31 installed above the unloading belt conveyor 6 to measure the distance to the top of the grain 10 that is piled up and flowing on the unloading belt conveyor 6; and a control device 32 that determines the cross-sectional area D of the grain 10 at the measurement position piled up on the unloading belt conveyor 6 and the volume of grain transported in a predetermined time based on the cross-sectional area D, based on the angle of repose θa that has been input in advance for the grain 10 and the measured distance B obtained by the measuring device 31.

Description

Technical Field

[0001] The present invention relates to a system for measuring the conveying flow rate of grains conveyed by a belt conveyor.

Background Art

[0002] In a country elevator, for example, paddy after being harvested is carried into the facility, dried, stored, husked, and prepared, and then shipped out as brown rice. Inside the facility, the roughly sorted raw paddy is dried by a dryer, stored in a silo, and then husked according to the shipment schedule, aligned to a certain size, and sorted to remove foreign substances such as stones, and then packed in bags and shipped out. In such a series of processes, it is desirable that a certain amount of paddy is conveyed to the husker, sorter, etc. according to the function, and if the conveying amount becomes uneven, the processing accuracy such as husking and sorting will be reduced.

[0003] The following Patent Document 1 discloses a grain conveying flow rate measurement system configured to sense the flow rate of grain flowing down in a conveying flow path after harvesting. In the conveying flow rate measurement system, a swingable detection plate whose upper end is pivotally supported is inclined by the amount of grain flowing in an inclined cylindrical grain flow path through which the grain flows down, and the inclination is detected by a potentiometer. Further, a vane wheel is pivotally supported rotatably on the downstream side thereof, and a configuration is provided in which the rotation speed is detected by detecting a magnet fixed to and rotating with the vane wheel by a reed switch. Therefore, in the conventional conveying flow rate measurement system, the flow rate of the grain is calculated from the cross-sectional area of the grain in the flow path based on the detection output of the potentiometer and the flow velocity of the grain in the flow path based on the rotation speed of the vane wheel.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] In country elevators, large quantities of grain are processed as they flow through the conveying channels. Therefore, in structures where components such as detection plates and impellers directly interact with the conveyed grain, as in the conventional example mentioned above, these components may malfunction, making accurate detection impossible, and increasing the likelihood of breakdowns. Furthermore, while conventional examples may involve contact between the grain and the detection plate or impeller to measure grain passing through a cylindrical grain channel, if the detection plate or impeller simply comes into contact with the grain flowing on the belt conveyor, the cross-sectional shape of the grain accumulated on the belt conveyor will change, making it impossible to accurately measure the flow rate.

[0006] Therefore, the present invention aims to provide a grain conveying flow rate measuring system for measuring the conveying flow rate of grain on a belt conveyor in order to solve the above problems. [Means for solving the problem]

[0007] The grain transport flow rate measuring system according to the present invention comprises a silo for storing grain, an discharge adjustment means provided at a discharge port formed at the bottom of the silo for adjusting the amount of grain discharged, a transport belt conveyor positioned below the silo for transporting the grain discharged from the discharge port, a measuring device installed above the transport belt conveyor for measuring the distance to the top of the grain piled up and flowing on the transport belt conveyor, and a control device that determines the cross-sectional area of ​​the grain piled up on the transport belt conveyor at the measurement position and the volume of grain transported in a predetermined time based on the angle of repose pre-input for the grain and the measurement distance obtained by the measuring device. [Effects of the Invention]

[0008] According to the above configuration, grain is discharged from the bottom of the silo for storing grain according to the discharge adjustment means and transported downstream by a transport belt conveyor located below it. At this time, a measuring device measures the distance to the top of the grain piled up and flowing on the transport belt conveyor, and the control device can determine the cross-sectional area of ​​the grain at the measurement position piled up on the transport belt conveyor and the volume of grain transported in a predetermined time based on that cross-sectional area, based on the angle of repose that has been input in advance for that grain and the measured distance to the top obtained by the measuring device, as the transport flow rate. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram illustrating an example of a country elevator. [Figure 2] This is a simplified diagram illustrating how grain discharged from a silo flows along a conveyor belt for transport. [Figure 3] This is a conceptual diagram illustrating the measurement method in a grain transport flow rate measurement system. [Figure 4] This graph shows the changes in the transport flow rate of grains. [Figure 5] This diagram shows the structure of a discharge section that uses an electric cylinder as an automatic discharge adjustment mechanism. [Figure 6] This diagram shows the structure of a discharge section using a rotary valve as an automatic discharge volume adjustment mechanism. [Modes for carrying out the invention]

[0010] One embodiment of the grain transport flow rate measuring system according to the present invention will be described below with reference to the drawings. The grain transport flow rate measuring system of this embodiment will be described using an example of a system incorporated into a country elevator. Figure 1 is a schematic diagram of an example of a country elevator. This country elevator 1 is equipped with a receiving grain lifter 2 and a silo lifter 3 in succession, and the transported grain is stored in a plurality of silos 5.

[0011] Above silo 5 is a loading belt conveyor 4, and grain is lifted upward by a silo hoisting machine 3 and sent to the loading belt conveyor 4. Multiple silos 5 are arranged side by side, and a predetermined amount of grain is fed from the loading belt conveyor 4 to each silo 5. The cylindrical silos 5 have an inverted cone-shaped bottom with an outlet 501 at the lower end for discharging the grain. Below the silos 5, which are arranged in a straight line, is an unloading belt conveyor 6 to receive the grain discharged from multiple outlets 501. Downstream of the unloading belt conveyor 6 is an unloading hoisting machine 7, which transports the grain for shipment.

[0012] For example, if the grain being transported to Country Elevator 1 is rice, a rough sorting machine 11 to remove impurities and diseased parts, and a dryer 12 to dry the rice grains that have just been harvested and still contain moisture are placed upstream of Silo 5 between the incoming grain lifter 2 and the silo grain lifter 3, and the rice is then sent into Silo 5 after passing through these machines. The rice is stored in Silo 5 in its unhulled state and is taken out of Silo 5 at the time of shipment. When shipped from Country Elevator 1, the rice is transported as brown rice, so a discharge grain lifter 7 is located downstream of the unloading belt conveyor 6, and a hulling machine 13 and a grain sorter 14 are installed to perform hulling and sorting processes on the rice grains.

[0013] The rice grains inside the silo 5 are continuously discharged from the open discharge port 501 and placed onto the belt of the transport belt conveyor 6, which has an endless track between rollers 21 and 22. Therefore, the rice grains accumulated on the transport belt conveyor 6 are sent from the upstream side to the downstream side of the transport belt conveyor 6. The rice grains that are transported to the discharge hoisting machine 7 are then carried up and sent to the hulling machine 13 and the grain sorting machine 14. The hulling machine 13 and other working machines have an appropriate amount of rice grains that corresponds to the processing capacity of the machine when performing tasks such as hulling. Therefore, it is desirable that the amount of rice grains flowing on the transport belt conveyor 6 matches that appropriate amount. However, the amount of rice grains discharged from the silo 5 per unit time may change due to clogging of the stored rice grains.

[0014] Previously, a discharge adjustment mechanism 24 was provided at the discharge port 501 of the silo 5, allowing the discharge amount to be changed by an operator. This adjustment was performed manually by the operator, who visually confirmed the flow rate of the rice grains flowing on the transport belt conveyor 6, or by checking the status of the rice hulling machine, etc. However, this conventional method, which relied on the operator's judgment, could not respond to changes in flow rate because the operator could not always be present to check. Therefore, the transport flow rate measurement system of this embodiment measures the transport flow rate of grains flowing on the transport belt conveyor 6 that transports grains downstream of the silo 5. It should be noted that the requirement to check the transport flow rate exists for grains other than rice as well as for this problem, so the transport flow rate measurement system is not limited to rice.

[0015] Figure 2 is a simplified diagram showing how grain discharged from a silo flows along the conveyor belt 6. The conveyor belt 6 has a conveyor belt 23 stretched over rollers 21 and 22 located at the beginning and end. The roller 21 at the beginning is a driven roller, with the output shaft of a drive motor 27 connected to its rotation axis, while the roller 22 at the end is a driven roller, which provides rotation to the conveyor belt 23. The conveyor belt 23 is stretched vertically over a pair of rollers 21 and 22 that are spaced apart in the grain transport direction (approximately horizontal) and have their rotation axes oriented horizontally (perpendicular to the transport direction). The upper part is the carrier section 231 for carrying the grain, and the lower part, which is reversed by the roller 22 at the end, is the return section 232.

[0016] The conveying flow rate per unit time of grain 10 transported downstream by the rotating conveyor belt 23 is determined by the amount of waste discharged from the silo 5 and the rotational speed of the conveyor belt 23. However, it is difficult to directly measure the amount of waste discharged from the silo 5 per unit time. Therefore, the conveying flow rate measuring system of this embodiment is configured to measure the conveying flow rate of grain 10 on the conveyor belt 23. Figure 3 is a conceptual diagram showing the measurement method in the conveying flow rate measuring system of this embodiment, and shows a cross-section perpendicular to the conveying direction of the discharge belt conveyor 6.

[0017] The discharge belt conveyor 6 has multiple intermediate rollers (not shown) between the rollers 21 and 22 at both ends, spaced at predetermined intervals in the direction of transport, to support the transport belt 23. Among these intermediate rollers, the carrier roller 25 that supports the carrier portion 231 of the transport belt 23 is configured with two rollers on the left and right so that the carrier portion 231, when viewed in the direction of travel, is concave. On the other hand, the return portion 232 of the transport belt 23 is composed of a single return roller 26 so that it is flat when viewed in the direction of travel.

[0018] The reason why the carrier part 231 has a V - shape with both ends in the width direction being higher and the central part being lower is to enable the grains 10 discharged from the silo 5 to flow in a generally constant deposition state. That is, in this embodiment, a method of measuring the conveying flow rate of the grains 10 based on the angle of repose θa of the grains 10 mounted on the conveying belt 23 is adopted. Therefore, when loading the grains 10 onto the conveying belt 23, it is necessary to create a deposition state in which the angle of repose θa occurs within a range of a predetermined width dimension without the grains 10 spreading in the width direction. Thus, the conveying belt 23 is configured in a shape that prevents the loaded grains 10 from spreading in the width direction so that the grains 10 are in a deposited state with a certain height.

[0019] The conveying belt 23 only needs to have a structure that makes the grains 10 in a stable deposition state, and it may be different from the V - shape with the deepest valley at the center in the width direction as shown in FIG. 3. For example, there may be a structure with three carrier rollers, the central carrier roller being horizontal and the left and right carrier rollers being upright, such that both sides in the width direction of the carrier part 231 are high and the central part forms a side - groove shape with a bottom of a certain width.

[0020] The granular grains 10 discharged from the silo 5 onto the conveying belt 23 by natural fall flow from the central part to both the left and right sides, forming a deposition state with a substantially symmetric inclined surface as shown in FIG. 3. Therefore, when a predetermined amount or more of the grains 10 accumulates, the granular grains 10 flow symmetrically to the left and right, and the maximum angle of the inclined surface becomes the angle of repose θa. Although the angle of repose θa varies depending on the type of the grains 10, for the same type of grains 10, it becomes a substantially constant value even if the accumulated amount (the height of the accumulated grains 10) is different. Therefore, in this embodiment, the angle of repose θa is determined in advance for different types of grains 10 such as rice and wheat and input into the control device 32 as calculation data.

[0021] Next, the transport flow rate measurement system of the present embodiment is provided with a measuring device 31 for obtaining the height of the grains 10 being transported, above the transport belt 23 and midway to the roller 22 on the terminal side. In particular, the measuring device 31 is arranged at a position where the rest angle θa at the top becomes substantially constant due to the stable deposition state during the flow in which the grains 10 are discharged from the silo 5 and transported by the transport belt 23. A laser distance meter is used for the measuring device 31 of the present embodiment, and the distance B to the top of the grains 10 flowing on the transport belt 23 can be measured in real time. And the measuring device 31 is connected to the control device 32, and in the control device 32, the transport flow rate of the grains 10 sent by the unloading belt conveyor 6 is calculated.

[0022] The installation height of the measuring device 31 is the distance A from the bottommost part of the carrier portion 231, and the distance B to the top of the grains 10 deposited on the transport belt 23 detected by the measuring device 31 is measured in real time. Also, since the rest angle θa in the grains 10 such as rice and wheat is constant for each, the change in the discharge amount of the grains 10 discharged from the silo 5 appears as the height C (= A - B) of the grains 10 deposited on the transport belt 23 shown in FIG. 3. Therefore, since the cross-sectional area D of the grains 10 deposited on the transport belt 23 follows the height C, in the transport flow rate measurement system of the present embodiment, a data table for obtaining the value of the cross-sectional area D corresponding to the height C for each type of grains 10 is created and stored in the control device 32. The cross-sectional area D is obtained by D = C^2 / (tanθa + tanθb), which is inversely proportional to the sum of the tangent functions of the rest angle θa in the grains 10 and the angle θb of the carrier portion 231 of the transport belt 23 with respect to the square value of the height C of the grains 10. <000,0100><000,0101> <000,0102>The drive motor 27 of the discharge belt conveyor 6 is equipped with a tachometer 28, such as an encoder. The drive motor 27 and the tachometer 28 are connected to a control device 32, which can control the conveying speed of the discharge belt conveyor 6 based on the value detected by the tachometer 28. Therefore, the conveying flow rate E of the grain 10 conveyed by the discharge belt conveyor 6 can be calculated based on the cross-sectional area D obtained from the height C. Here, the conveying flow rate E can be obtained as the volume of grain 10 flowing per unit time, or it may be converted to a mass obtained by multiplying that volume by a predetermined bulk density (apparent density) that has been measured and input in advance.

[0024] The grain 10 flowing downstream by the discharge belt conveyor 6 does not have a constant height C, resulting in some unevenness. Therefore, calculating the cross-sectional area D according to the change in height C would place a heavy burden on the calculation of the transport flow rate E. In this embodiment, the average value of the height C of the grain 10 detected per unit time is calculated, and the volume (or mass) obtained by multiplying the cross-sectional area D corresponding to that height C by the distance traveled per unit time is calculated as the transport flow rate E. In this way, the transport flow rate measurement system of this embodiment can accurately grasp the transport flow rate E of the grain 10 transported by the discharge belt conveyor 6. Then, by adding the transport flow rate E for a predetermined time, it becomes possible to determine the total amount of grain 10 discharged from the silo 5 for shipment, or the amount shipped within a certain period of time.

[0025] Furthermore, regarding the unevenness in the height C of the grain 10 flowing on the conveyor belt 6, a moving average may be used to calculate the average of the most recent set of measurements. For example, if the flow rate is displayed numerically on the screen in real time, it becomes difficult to grasp the current value and the trend of increase or decrease if the value of height C fluctuates wildly. Even in such cases, using a moving average makes it easier to grasp the trend of increase or decrease in the height (flow rate) of the grain 10. Note that the value of the moving average differs depending on the number of elements averaged and the measurement period, so the appropriate number of elements should be determined based on the type of grain 10 and various other conditions.

[0026] Next, the grain transport flow rate measurement system can calculate the transport flow rate E and add configurations to transport the grain 10 within an appropriate flow rate range. This appropriate flow rate range refers to an amount corresponding to the processing capacity of downstream implements such as the rice hulling machine 13. As shown in Figure 3, a monitor 33 is connected to the control device 32 to display the changes in the calculated transport flow rate E. Specifically, the transport flow rate E is displayed as shown in Figure 4. Figure 4 is a graph showing the changes in the transport flow rate E, with time on the horizontal axis and the volume of grain 10 flowing per unit time (transport flow rate E) on the vertical axis. The lower limit F1 and upper limit F2 of the appropriate flow rate range F corresponding to the grain 10 are displayed as thresholds.

[0027] As mentioned above, the calculated transport flow rate E falls within the appropriate flow rate range F when the grain 10 is being discharged stably from the silo 5. On the other hand, if the grain 10 in the silo 5 becomes clogged, the transport flow rate E will fall below the lower limit F1, and conversely, if the discharge force increases, the transport flow rate E will exceed the upper limit F2. This situation is represented as shown in graph G1 on the monitor 33. By checking this graph G1, the operator can adjust the discharge rate adjustment means 24 provided at the discharge port 501 of the silo 5 (for example, by adjusting the opening of the slide adjustment plate). Furthermore, to avoid the operator having to constantly monitor the monitor 33, if graph G1 falls outside the appropriate flow rate range F, a warning display may be shown on the monitor 33, and an alarm sound may be emitted to notify the operator.

[0028] The grain transport flow rate measurement system can automate flow rate adjustment by obtaining the information shown in Figure 4 regarding the transport flow rate E of the grain 10. Therefore, the discharge adjustment means 24 installed at the discharge port 501 of the silo 5 will be improved from manual to automatic. Figure 5 shows the structure of the discharge port 501 using an electric cylinder 35 as an example of an automatic discharge adjustment means. Here, the rod 351 of the electric cylinder 35 is connected to a slidable opening adjustment plate 41 that is provided to adjust the opening degree of the discharge port 501. The electric cylinder 35 is connected to a control device 32, and stroke control for opening degree adjustment is performed.

[0029] Therefore, if the transport flow rate E deviates from the appropriate flow rate range F, the electric cylinder 35 is controlled according to the direction of the deviation. As shown in Figure 4, when the transport flow rate E decreases, the electric cylinder 35 is controlled to contract so that the opening adjustment plate 41 is displaced in the opening direction. On the other hand, when the transport flow rate E increases, the electric cylinder 35 is controlled to extend so that the opening adjustment plate 41 is displaced in the closing direction. In this case, in order to return the transport flow rate E to the appropriate flow rate, as shown in Figure 4, a lower control value F3 and an upper control value F4 are set as adjustment completion thresholds within the appropriate flow rate range F. There is a time lag between the adjustment operation of the electric cylinder 35 and the control result of the transport flow rate E. Therefore, the electric cylinder 35 adjusts the opening of the discharge port 501 by stepwise displacement so that the transport flow rate E gradually approaches the lower control value F3 or the upper control value F4, and stops the extension and retraction operation of the electric cylinder 35 when each value is reached.

[0030] Next, Figure 6 shows the structure of a discharge section using a rotary valve 36 as an example of an automatic discharge adjustment means. The rotary valve 36 incorporated into the discharge port 501 of the silo 5 is configured such that a rotor 361, which has multiple blades arranged radially, rotates inside the casing by a motor (not shown). With this rotary valve 36, multiple pockets formed by the multiple blades rotate at the bottom of the silo 5, and the grain 10 that has entered the pockets at the top is carried down and discharged in predetermined amounts. The rotary valve 36 rotates the rotor 361 under the control of a motor connected to a control device 32, and the discharge rate per unit time is adjusted.

[0031] Therefore, if the conveyed flow rate E falls outside the appropriate flow rate range F, the rotational speed of the rotor 361 is adjusted. As shown in Figure 4, when the conveyed flow rate E decreases, the motor control is performed to increase the rotational speed of the rotor 361. On the other hand, when the conveyed flow rate E increases, the motor control is performed to decrease the rotational speed of the rotor 361. In the rotary valve 36 as well, in order to return the conveyed flow rate E to the appropriate flow rate, stepwise rotational control is performed so that the conveyed flow rate E gradually approaches the lower control value F3 or upper control value F4 shown in Figure 4, and the rotation is kept constant when each value is reached.

[0032] Therefore, according to the grain transport flow rate measurement system of this embodiment, the transport flow rate E of the grain 10 can be calculated in real time while the grain 10 discharged from the silo 5 is being transported, and the total amount of grain 10 transported in a predetermined transport process can also be calculated. Furthermore, even if there is a change in the flow rate of the grain 10 flowing on the discharge belt conveyor 6, the transport flow rate E can be checked in real time, making it possible to adjust the flow rate to stay within an appropriate flow rate range F according to the function of the downstream work machine, such as the rice hulling machine 13.

[0033] By displaying the calculated grain transport flow rate E on the monitor 33, the operator can accurately grasp the transport status and operate discharge adjustment means such as the opening adjustment plate. Furthermore, in the grain transport flow rate measurement system, by providing an automatic discharge adjustment means at the discharge port 501 of the silo 5, automation is possible to set the transport flow rate E to an appropriate value.

[0034] Although one embodiment of the present invention has been described above, the present invention is not limited thereto, and various modifications are possible without departing from its spirit. For example, although it was stated that a laser rangefinder is used in the measuring device 31 of the above embodiment, any rangefinder that can measure distance without contact is acceptable, and for example, an ultrasonic rangefinder may be used.

[0035] Furthermore, while an example of a data table for determining the cross-sectional area D in the present invention, in which the angle of repose θa is set for each type of grain, the present invention is not limited to this, and the stacking of grain 10 on the conveyor belt 23 may be measured in three dimensions using the measuring device 31, and the angle of repose θa may be determined from the approximate value. Furthermore, the selection of the data table may be done manually or automatically. In particular, if there are multiple silos 5, each containing different types and varieties of grain, the value of the angle of repose θa may be used in the calculation of the cross-sectional area D in the control device 32, in association with the discharge command to silo 5 that is not explicitly specified. [Explanation of Symbols]

[0036] 1…Country elevator 5…Silo 6…Export belt conveyor 10…Grain 13…Rice huller 21,22…Roller 23…Conveyor belt 25…Carrier roller 26…Return roller 27…Drive motor 28…Tachometer 31…Measuring device 32…Control device 33…Monitor 35…Electric cylinder 36…Rotary valve

Claims

1. Silos for storing grain, The discharge port formed at the bottom of the silo is provided with a discharge adjustment means for adjusting the amount of grain discharged, A conveyor belt for transporting grain discharged from the discharge port is located below the silo, A measuring device installed above the aforementioned discharge belt conveyor for measuring the distance to the top of the grain piled up and flowing on the discharge belt conveyor, A control device that determines, based on the angle of repose pre-entered for the grain and the measurement distance obtained by the measuring device, the cross-sectional area of ​​the grain at the measurement position accumulated on the transport belt conveyor and the volume of grain transported in a predetermined time based on the cross-sectional area, A grain transport flow rate measuring system having the following features.

2. A grain transport flow rate measuring system according to claim 1, comprising a monitor connected to the control device and displaying the volume of grain calculated by the control device or the mass calculated from said volume as the transport flow rate.

3. The grain transport flow rate measuring system according to claim 1 or 2, wherein the discharge rate adjustment means is an automatic discharge rate adjustment means connected to the control device, which automatically adjusts and controls the amount of grain discharged from the silo outlet based on the volume of grain calculated by the control device or the mass calculated from said volume.

4. The grain transport flow rate measuring system according to claim 3, wherein the automatic discharge adjustment means comprises a rod of an electric cylinder connected to an opening adjustment plate slidably provided with respect to the discharge port of the silo, and the amount of grain discharged is automatically adjusted by stroke control of the control device with respect to the electric cylinder.

5. The grain transport flow rate measuring system according to claim 3, wherein the automatic discharge adjustment means is a rotary valve incorporated into the discharge port of the silo, and the amount of grain discharged is automatically adjusted by the rotational control of the control device with respect to the motor of the rotary valve.

6. The grain transport flow rate measuring system according to claim 3, wherein the control device performs automatic adjustment control to the automatic discharge adjustment means so that the transport flow rate falls within an appropriate flow rate range corresponding to the processing capacity of the work machine located downstream of the discharge belt conveyor, when the transport flow rate is the calculated volume of grain or the mass calculated from said volume.

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