Moisture detection device

Abstract

To provide a moisture content detecting device capable of accurately detecting a moisture content contained in grains.SOLUTION: Grains are crushed between a pair of electrode rollers of a moisture sensor 16 by rotation of the electrode rollers, and a signal in accordance with electric resistance value between the electrode rollers is outputted by a signal output part 45 with the crushed objects (crushed grains) of the grains between the electrode rollers. An electric resistance value between the electrode rollers changes depending on a temperature of the grains to be crushed between the electrode rollers changes. Then, a voltage value of the signal outputted by the signal output part 45 or a moisture content acquired by the moisture content acquisition part 43 is corrected according to the temperature of the grains.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a moisture content detector that detects the amount of moisture contained in grains. [Background technology]

[0002] In a combine harvester, the base of the culms planted in the field is cut by a harvester, and the cut culms are transported from the harvester to a thresher where they are threshed. Grains such as rice grains that have fallen off the culms are transported from the thresher to a discharge section installed at the top of a grain tank and discharged from the discharge section into the grain tank.

[0003] Some combine harvesters are provided with a moisture sensor (moisture meter) in the grain tank that measures the amount of moisture contained in grains. The moisture sensor is disposed in a position where it can receive grains discharged from the discharge section. The moisture sensor is, for example, an electrical resistance type moisture sensor, and is provided with a pair of electrode rollers. Grains received in the moisture sensor are caught between the pair of electrode rollers as the pair of rollers rotate, and are crushed between the electrode rollers. With the crushed grains sandwiched between the electrode rollers, the electrical resistance between the electrode rollers is measured, and the amount of moisture contained in the grains is determined from the electrical resistance value (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6451513 Summary of the Invention [Problem to be solved by the invention]

[0005] However, a configuration using an electrical resistance type moisture sensor has a problem in that the accuracy of detecting the amount of moisture contained in the grain is low.

[0006] An object of the present invention is to provide a moisture content detection device capable of detecting the moisture content in grains with high accuracy. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the moisture content detection device of the present invention is a device that detects the moisture content contained in grains, and includes a case for receiving the grains, a pair of electrode rollers arranged close to each other within the case, a motor for rotating the electrode rollers, a drive control unit for rotating the pair of electrode rollers by the motor, a signal output unit that outputs a signal corresponding to the electrical resistance value between the electrode rollers when the grains are crushed between the electrode rollers by the rotation of the pair of electrode rollers, a moisture content acquisition unit that acquires a moisture content corresponding to the voltage value of the signal output from the signal output unit using a previously created calibration curve, and a correction unit that corrects the voltage value of the signal output from the signal output unit or the moisture content acquired by the moisture content acquisition unit in accordance with the temperature of the grain.

[0008] According to this configuration, the grains are crushed between the pair of electrode rollers by the rotation of the electrode rollers, and in a state where the crushed grains (crushed grains) are sandwiched between the electrode rollers, a signal corresponding to the electrical resistance value between the electrode rollers is output from the signal output unit. Then, the moisture content acquisition unit acquires the moisture content corresponding to the voltage value of the signal output from the signal output unit using a calibration curve.

[0009] The electrical resistance between the electrode rollers varies depending on the temperature of the grains being crushed between the electrode rollers. That is, as the temperature of the grains being crushed between the electrode rollers increases, the electrical resistance between the electrode rollers decreases. Therefore, the voltage value of the signal output from the signal output unit or the moisture content acquired by the moisture content acquisition unit is corrected according to the temperature of the grains. As a result, the moisture content in the grains can be detected with high accuracy.

[0010] The moisture content detection device further includes a temperature sensor that detects the temperature of the grains received in the case, and the correction unit may correct the voltage value of the signal output from the signal output unit or the moisture content acquired by the moisture content acquisition unit in accordance with the temperature detected by the temperature sensor.

[0011] For example, if noise is mixed into the signal output from the signal output unit, the voltage value of the signal will not correspond to the electrical resistance between the electrode rollers, and the moisture content of the grain cannot be correctly obtained from the voltage value of the signal.

[0012] Therefore, an averaging process may be performed on the voltage value of the signal output from the signal output unit, and the moisture content corresponding to the voltage value averaged by the averaging process may be obtained using a calibration curve. In this way, even if noise is mixed into the signal output from the signal output unit, the influence of the noise can be eliminated by the averaging process.

[0013] The drive control unit may continuously rotate a pair of electrode rollers using a motor while grains are stored in the case, and the moisture content acquisition unit may use a signal output from the signal output unit for a certain period of time while the pair of electrode rollers are rotating to acquire the moisture content.

[0014] According to this configuration, instead of squeezing a single grain between a pair of electrode rollers and acquiring a signal corresponding to the electrical resistance between the electrode rollers, the grains stored in the case are squeezed between a pair of electrode rollers and a signal corresponding to the electrical resistance between the electrode rollers is output. Therefore, even if foreign matter such as straw or insects gets mixed in with the grains in the case, the effect of the foreign matter on the change in the electrical resistance is small. Therefore, the moisture content in the grains can be detected more accurately.

[0015] In addition, by setting the period during which a signal is stably output from the signal output unit to a fixed period, and using the signal output from the signal output unit during that fixed period to obtain the moisture content, the voltage value averaged by the averaging process becomes stable, making it possible to detect the moisture content in the grain with greater accuracy.

[0016] The moisture content acquisition unit may switch the content of the averaging process depending on the size of the kernel.

[0017] Specifically, when the size of the grain is a predetermined small size, for example when the grain is rice or wheat, the moisture content acquisition unit may, in the averaging process, sample the voltage value of the signal output from the signal output unit, calculate a sample average value and standard deviation from the sampled values, and calculate an averaged voltage value by performing a calculation according to an arithmetic formula that uses the sample average value and standard deviation.

[0018] On the other hand, when the size of the grain is a predetermined large size, for example when the grain is barley, it is preferable that in the averaging process, the moisture content acquisition unit acquires the peak value of the voltage value of the signal output from the signal output unit at regular intervals and calculates the average value of the acquired peak values ​​as the averaged voltage value.

[0019] Large grains such as barley are less likely to enter between the pair of electrode rollers than small grains such as rice and wheat. Therefore, grains enter between the electrode rollers intermittently, and the electrical resistance between the electrode rollers changes before and after a large grain enters between the electrode rollers, causing a change in the voltage value of a signal corresponding to the electrical resistance value. By obtaining the peak value of the voltage value of the signal output from the signal output unit at regular intervals, it is possible to obtain the voltage value of a signal corresponding to the electrical resistance between the electrode rollers when the grains are being crushed between the electrode rollers. As a result, the moisture content of the grains can be detected with even greater accuracy.

[0020] If a calibration curve created without taking the averaging process into consideration is used to obtain the moisture content from the voltage value, the voltage value will change before and after the averaging process, and an error due to this change may appear in the moisture content.

[0021] Therefore, it is preferable that the calibration curve used to obtain the moisture content from the voltage value is created by performing an averaging process with the same content as the averaging process performed when obtaining the moisture content, so that the moisture content in the grain can be obtained with high accuracy from the voltage value averaged by the averaging process. Effect of the Invention

[0022] According to the present invention, the moisture content in grains can be detected with high accuracy. [Brief description of the drawings]

[0023] [Figure 1] 1 is a right side view of a combine harvester in which a moisture content detection device according to one embodiment of the present invention is mounted. [Diagram 2] This is an oblique view of the grain tank of a combine harvester, seen from the right front side. [Diagram 3] This is an oblique view of the grain tank of a combine harvester viewed from the right front side, showing the moisture sensor housing portion exposed to the front. [Figure 4] This is an oblique view of the moisture sensor as seen from inside the grain tank. [Diagram 5] FIG. 2 is a block diagram showing a main part of the electrical configuration of the combine harvester. [Figure 6] 10 is a flowchart showing a flow of roller drive control. [Figure 7] 10 is a flowchart showing the flow of a moisture amount acquisition process. [Figure 8] FIG. 11 is a diagram showing an example of a change over time in the voltage value (signal voltage) of a signal output from a signal output unit when small-sized kernels are crushed between electrode rollers. [Figure 9] FIG. 11 is a diagram showing an example of a change over time in the voltage value (signal voltage) of a signal output from a signal output unit when large-sized kernels are crushed between electrode rollers. [Figure 10] 5 is a diagram showing an example of the relationship between the voltage value (signal voltage) of a signal output from a signal output unit and the moisture content of grain. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0025] <Overall configuration of combine harvester> FIG. 1 is a right side view of a combine harvester 1 on which a moisture content detection device according to one embodiment of the present invention is mounted.

[0026] The combine harvester 1 is an example of a harvesting machine that harvests and threshes culms while traveling in a farm field. The combine harvester 1 employs a pair of left and right crawlers 2 as a traveling device capable of traveling over uneven ground such as a farm field, and a cabin 4 and a grain tank 5 are provided on a machine body 3 supported by the pair of left and right crawlers 2.

[0027] The cabin 4 is disposed on the front end of the crawler 2. The cabin 4 provides a space for the driver inside, and within the space, for example, a driver's seat where the driver sits, and operation members such as an operation lever and an operation pedal are disposed. An openable door 6 is provided on the right side of the cabin 4, and the driver can enter the cabin 4 by opening the door 6.

[0028] The grain tank 5 is located behind the cabin 4 on the crawler 2 .

[0029] The machine body 3 of the combine 1 is also provided with a reaping device 7 and a thresher (not shown). The reaping device 7 is disposed in front of the crawler 2, and as the combine 1 advances, it reaps the culms planted in the field. The thresher is disposed on the left side of the grain tank 5, and the base side of the culms reaped by the reaping device 7 is transported to the rear side by a threshing feed chain, and the tip side of the culms is supplied to a threshing chamber for threshing. Then, the grains removed from the culms are transported from the thresher to the grain tank 5, where the grains are stored. An unloader 8 is connected to the grain tank 5, and the grains stored in the grain tank 5 can be removed by the unloader 8 and discharged outside the machine.

[0030] <Moisture sensor> 2 and 3 are perspective views of the grain tank 5 as viewed from the right front side.

[0031] The grain tank 5 is surrounded by side walls 11 on all sides, and is container-shaped with the space surrounded by the side walls 11 closed from above and below by a top wall 12 and a bottom wall 13. Although not shown, a discharge section is provided inside the grain tank 5, for example, in the upper part of the left side portion of the side wall 11, in the center in the front-to-back direction. The discharge section is provided with rotating blades that rotate around an axis that extends in the vertical direction. Grains are transported from the threshing device to the discharge section, swept away by the rotating blades, and thrown out of the discharge section toward the right front side.

[0032] A moisture sensor housing 15 is formed in the front portion of the side wall 11, i.e., the front wall 14, recessed toward the rear, as shown in Fig. 3. A moisture sensor 16 is housed in the moisture sensor housing 15. The moisture sensor housing 15 is usually covered by a lid 17 attached to the outer surface of the front wall 14, as shown in Fig. 2. Fig. 3 shows the state with the lid 17 removed.

[0033] FIG. 4 is a perspective view of the moisture sensor 16 as seen from inside the grain tank 5.

[0034] The moisture sensor 16 includes a box-shaped sensor case 21. A receiving opening 22 for receiving grains into the sensor case 21 is formed on the rear surface of the sensor case 21. The receiving opening 22 has a symmetrical shape, and includes a V-shaped lower side 23 that opens upward, a first left side 24 that extends upward from the upper left end of the lower side 23 and inclines at a relatively small angle to the left in the up-down direction (vertical direction), a second left side 25 that extends upward from the upper end of the first left side 24 and inclines at a relatively large angle to the left in the up-down direction, a first right side 26 that extends upward from the upper right end of the lower side 23 and inclines at a relatively small angle to the right in the up-down direction, and a second right side 27 that extends upward from the upper end of the first right side 26 and inclines at a relatively large angle to the right in the up-down direction. A flat surface extends forward from each of the first left side 24, the second left side 25, the first right side 26, and the second right side 27, and these flat surfaces function as guide surfaces that guide the kernels into the sensor case 21.

[0035] A pair of electrode rollers 31, 32 are provided in the roller accommodating space behind the receiving port 22 within the sensor case 21. The electrode rollers 31, 32 have integral roller shafts 33, 34, respectively, which are parallel to each other and extend in the front-rear direction. The peripheral surfaces of the electrode rollers 31, 32 are arranged close to each other in the left-right direction. A gap is provided between the peripheral surfaces of the electrode rollers 31 and 32 according to the size of the rice grains, for example, a gap slightly smaller than the width of the rice grains (the length in the direction perpendicular to the longitudinal direction). A large number of minute projections and recesses are formed on the peripheral surfaces of the electrode rollers 31, 32.

[0036] A motor 35 (see FIG. 5) is provided inside the sensor case 21, and the pair of electrode rollers 31, 32 rotate forward and backward by the power of the motor 35. When the electrode rollers 31, 32 rotate forward, the left electrode roller 31 rotates clockwise and the right electrode roller 32 rotates counterclockwise when viewed from inside the grain tank 5. When the electrode rollers 31, 32 rotate backward, the left electrode roller 31 rotates counterclockwise and the right electrode roller 32 rotates clockwise when viewed from inside the grain tank 5.

[0037] In addition, a guide member 36 is attached to the inner surface of the front wall 14. The guide member 36 has a shape obtained by bending a flat plate into a V-shape, with the bending line positioned lower toward the front and the front end (lower end) positioned on a plane extending forward from the lower side 23 of the receiving opening 22 of the sensor case 21.

[0038] Some of the grains scattered from the discharge section in the grain tank 5 reach the position of the sensor case 21 and are directly received into the sensor case 21 through the receiving port 22 of the sensor case 21. In addition, the grains that reach the guide member 36 flow on the guide member 36 toward the sensor case 21, drop from the guide member 36, and are received into the sensor case 21 through the receiving port 22. The grains received into the sensor case 21 through the receiving port 22 are accumulated on the electrode rollers 31, 32. Then, when the electrode rollers 31, 32 rotate forward, the grains are sandwiched between the electrode rollers 31, 32 and crushed.

[0039] When the electrode rollers 31, 32 rotate in the reverse direction, brushes (not shown) come into contact with the circumferential surfaces of the electrode rollers 31, 32, and the circumferential surfaces (surfaces) of the electrode rollers 31, 32 are cleaned.

[0040] The bottom of the roller housing space in which the electrode rollers 31, 32 are housed is open. Therefore, the grains received into the sensor case 21 from the receiving opening 22 and the crushed grains scraped off from the peripheral surfaces of the electrode rollers 31, 32 do not accumulate in the roller housing space except on the electrode rollers 31, 32, but are discharged from the roller housing space into the grain tank 5 through a return passage 37 provided below the moisture sensor 16.

[0041] <Electrical configuration of combine> FIG. 5 is a block diagram showing a main part of the electrical configuration of the combine harvester 1. As shown in FIG.

[0042] The combine harvester 1 is equipped with an ECU (Electronic Control Unit) 41. The ECU 41 includes a microcomputer (microcontroller), and the microcomputer includes, for example, a CPU, a non-volatile memory such as a flash memory, and a volatile memory such as a DRAM (Dynamic Random Access Memory).

[0043] The ECU 41 essentially has a drive control unit 42, a moisture content acquisition unit 43, and a correction unit 44 as functional processing units for detecting the moisture content of the grain stored in the grain tank 5. These functional processing units are realized in software by program processing, or by hardware such as a logic circuit, or by a combination of these.

[0044] The drive control unit 42 controls the motor 35 to rotate the electrode rollers 31 and 32 in the forward and reverse directions.

[0045] The moisture content acquiring unit 43 receives an output signal from a signal output unit 45 provided in the moisture sensor 16. When grains are crushed between the electrode rollers 31, 32 by the forward rotation of the electrode rollers 31, 32, the signal output unit 45 outputs a signal having a voltage value corresponding to the electrical resistance value between the electrode rollers 31, 32. This signal is, for example, a current value flowing between the electrode rollers 31, 32 in a state where a constant voltage is applied between the electrode rollers 31, 32. The smaller the electrical resistance value between the electrode rollers 31, 32, the larger the voltage value of the signal output from the signal output unit 45, and the larger the electrical resistance value between the electrode rollers 31, 32, the smaller the voltage value of the signal output from the signal output unit 45. The moisture content acquiring unit 43 performs an averaging process to average the voltage value of the signal output from the signal output unit 45, and acquires the moisture content corresponding to the averaged voltage value using a calibration curve 46 for rice and wheat or a calibration curve 47 for barley stored in a non-volatile memory. The averaging process, the contents of the calibration curve for rice and wheat 46 and the calibration curve for barley 47 will be described later.

[0046] A detection signal from a temperature sensor 48 provided in the moisture sensor 16 is input to the correction unit 44. The temperature sensor 48 is disposed above the electrode rollers 31, 32 inside the sensor case 21, and outputs a detection signal of a voltage value corresponding to the temperature of the grains accumulated on the electrode rollers 31, 32.

[0047] <Roller drive control> FIG. 6 is a flowchart showing the flow of roller drive control.

[0048] In order to detect the moisture content of the grain stored in the grain tank 5, the drive control unit 42 of the ECU 41 performs roller drive control for controlling the drive of the pair of electrode rollers 31, 32 of the moisture sensor 16.

[0049] In the roller drive control, it is determined whether or not the timing to start detecting the moisture content of the grains discharged (transported) into the grain tank 5 has arrived (step S11).

[0050] When the grains continue to be discharged into the grain tank 5 for a certain period of time, it is determined that the timing to start detecting the moisture content of the grains has arrived (YES in step S11), and the motor 35 starts to rotate in the forward direction (step S12). The forward rotation of the motor 35 rotates the electrode rollers 31 and 32 in the forward direction. Since the grains have been discharged into the grain tank 5 for a certain period of time, a certain amount (a predetermined number of grains) or more of grains have accumulated in the sensor case 21 (on the electrode rollers 31 and 32) of the moisture sensor 16. When the electrode rollers 31 and 32 rotate in the forward direction, the grains are sandwiched between the electrode rollers 31 and 32 and crushed. While the electrode rollers 31 and 32 are rotating in the forward direction, a certain voltage is applied between the electrode rollers 31 and 32, and a signal having a voltage value corresponding to the electrical resistance value between the electrode rollers 31 and 32 is output from the signal output unit 45 of the moisture sensor 16.

[0051] After the electrode rollers 31, 32 start to rotate in the normal direction, it is determined whether or not the timing to end the moisture content detection has arrived (step S13).

[0052] When a certain operating time has elapsed since the start of the forward rotation of the electrode rollers 31, 32, it is determined that the timing for ending detection of the moisture content of the grains has arrived (YES in step S13). Then, the motor 35 is stopped once, and then driven in the reverse direction (step S14). The reverse driving of the motor 35 rotates the electrode rollers 31, 32 in the reverse direction, and the peripheral surfaces of the electrode rollers 31, 32 are cleaned. When the reverse driving of the motor 35 continues for a certain cleaning time, it is determined that cleaning has ended (YES in step S15), and the motor 35 is stopped. The stopping of the motor 35 stops the electrode rollers 31, 32 (step S16), and the roller drive control ends.

[0053] <Moisture content acquisition process> FIG. 7 is a flowchart showing the flow of the moisture content acquisition process.

[0054] While the electrode rollers 31, 32 are rotating in the forward direction, a signal having a voltage value corresponding to the electrical resistance value between the electrode rollers 31, 32 is output from the signal output unit 45 of the moisture sensor 16. When the signal output from the signal output unit 45 is input to the moisture amount acquisition unit 43 of the ECU 41, the moisture amount acquisition unit 43 starts a moisture amount acquisition process.

[0055] In the moisture content acquisition process, it is determined whether the size of the grain to be detected for moisture content is a predetermined small size (step S21). The small size is assumed to be the size of rice and wheat. Therefore, the determination of whether the size of the grain is small is synonymous with the determination of whether the grain is rice or wheat. The combine harvester 1 can be used, for example, to harvest rice, wheat, and barley, and since the control of threshing by the threshing device needs to be changed according to the grain to be harvested, before starting the operation of the combine harvester 1, the user sets whether the grain to be harvested is rice, wheat, or barley on a meter panel (not shown) provided on the driver's cab. The moisture content acquisition unit 43 determines whether the size of the grain to be detected for moisture content is small based on the setting.

[0056] If the size of the grain for which moisture content is to be detected is small (YES in step S21), that is, if the grain for which moisture content is to be detected is unhulled or wheat, an averaging process is performed using an averaging algorithm (step S22).

[0057] FIG. 8 is a diagram showing an example of the change over time in the voltage value (signal voltage) of the signal output from the signal output unit 45 when small-sized grains are crushed between the electrode rollers 31 and 32. As shown in FIG.

[0058] Since a gap is provided between the peripheral surfaces of the electrode rollers 31 and 32 according to the size of the rice grains, small grains such as rice grains or wheat can easily get between the electrode rollers 31 and 32. Therefore, when the electrode rollers 31 and 32 rotate in the forward direction, the grains on the electrode rollers 31 and 32 are continuously caught between the electrode rollers 31 and 32 and crushed. Therefore, as shown in Fig. 9, there is little fluctuation in the voltage value of the signal output from the signal output unit 45 from when the voltage value rises until the grains disappear from the electrode rollers 31 and 32.

[0059] Taking this characteristic into consideration, in the averaging process using the averaging algorithm, the voltage value of the signal input from the signal output unit 45 to the moisture content acquisition unit 43 during a fixed period during the forward rotation of the electrode rollers 31, 32 is sampled at a predetermined sampling period. The fixed period is set to a period during which a signal is stably output from the signal output unit 45, for example, a period from 0.2 seconds to 5.2 seconds after the electrode rollers 31, 32 start to rotate forward. Then, the sample average value and standard deviation are calculated from the sampled values, and a calculation is performed according to the following formula to calculate an average value (averaged voltage value) of the voltage values ​​of the signal output from the signal output unit 45.

[0060] Averaged voltage value = sample mean + standard deviation x S where S is a constant

[0061] Thereafter, as shown in Fig. 7, the voltage value averaged by the averaging process is converted into a moisture content (moisture value) using the rough rice / wheat calibration curve 46 (step S23). The moisture content is, for example, a moisture content percentage (%) based on weight. When the moisture content is acquired by the conversion, the moisture content acquisition process is terminated.

[0062] The calibration curve 46 for rice and wheat is created by an experiment using the moisture sensor 16. That is, a predetermined amount of small-sized grains (rice or wheat) is put on the electrode rollers 31, 32 of the moisture sensor 16. The moisture content of the grains has already been detected by another moisture sensor and is known. When the electrode rollers 31, 32 are rotated forward and a signal of a voltage value corresponding to the electric resistance value between the electrode rollers 31, 32 is output from the signal output unit 45, an averaging process is performed by the averaging algorithm described above, and a voltage value averaged by the averaging process is obtained. Then, the voltage value is associated with the known moisture content of the grain. The above experiment is repeated using grains of the same kind but with different moisture contents, and thus a calibration curve 46 for rice and wheat is created, which shows the relationship between the voltage value averaged by the averaging process by the averaging algorithm and the moisture content contained in the grain.

[0063] On the other hand, if the size of the grain for which moisture content is to be detected is large and not small (NO in step S21), that is, if the grain for which moisture content is to be detected is barley, averaging processing is performed using a peak algorithm (step S24).

[0064] FIG. 9 is a diagram showing an example of the change over time in the voltage value (signal voltage) of the signal output from the signal output unit 45 when large-sized kernels are crushed between the electrode rollers 31 and 32. As shown in FIG.

[0065] Large grains such as barley are less likely to enter between the electrode rollers 31, 32 than small grains such as rice and wheat. Therefore, grains enter between the electrode rollers 31, 32 intermittently, and the electrical resistance between the electrode rollers changes before and after a large grain enters between the electrode rollers. Therefore, as shown in Fig. 10, the voltage value of the signal output from the signal output unit 45 fluctuates greatly.

[0066] Taking this characteristic into consideration, in the averaging process using the peak algorithm, the signal input from the signal output unit 45 to the moisture content acquisition unit 43 during a fixed period during the forward rotation of the electrode rollers 31, 32 is targeted, and a peak value (maximum value) of the voltage value is acquired for each fixed interval (for example, every second). Then, the simple average value of the acquired peak values ​​is calculated as a value obtained by averaging the voltage values ​​of the signal output from the signal output unit 45 (averaged voltage value).

[0067] 7, the voltage value averaged by the averaging process is converted into a moisture content (moisture value) using the barley calibration curve 47 (step S25). When the moisture content is acquired by this conversion, the moisture content acquisition process is terminated.

[0068] The barley calibration curve 47 is created by an experiment using the moisture sensor 16. That is, a predetermined amount of large-sized grains, i.e., barley, is put on the electrode rollers 31, 32 of the moisture sensor 16. The moisture content of the grains has already been detected using another moisture sensor and is known. When the electrode rollers 31, 32 are rotated forward and a signal of a voltage value corresponding to the electrical resistance value between the electrode rollers 31, 32 is output from the signal output unit 45, an averaging process using the peak algorithm described above is performed, and a voltage value averaged by the averaging process is obtained. Then, the voltage value is associated with the known moisture content of the grain. The above experiment is repeated using the same kind of grains with different moisture contents, and a barley calibration curve 47 is created that shows the relationship between the voltage value averaged by the averaging process using the peak algorithm and the moisture content contained in the grains.

[0069] <Correction process> FIG. 10 is a diagram showing an example of the relationship between the voltage value of the signal output from the signal output unit 45 (signal voltage) and the moisture content of grains.

[0070] The electrical resistance value between the electrode rollers 31, 32 varies depending on the temperature of the grains crushed between the electrode rollers 31, 32. That is, as the temperature of the grains crushed between the electrode rollers 31, 32 increases, the electrical resistance value between the electrode rollers 31, 32 decreases. Therefore, the relationship between the voltage value of the signal output from the signal output unit 45 and the moisture content of the grains shifts to the side where the voltage value increases as the grain temperature increases, as shown in Fig. 10.

[0071] Correction unit 44 of ECU 41 shifts paddy / wheat calibration curve 46 and barley calibration curve 47 by an amount corresponding to the temperature of the grain. Then, in the moisture content acquisition process by moisture content acquisition unit 43 of ECU 41, the voltage value averaged by the averaging process is converted into moisture content using paddy / wheat calibration curve 46 or barley calibration curve 47 after shifting (correction) by correction unit 44. As a result, the voltage value averaged by the averaging process or the moisture content acquired by converting the voltage value is corrected according to the temperature of the grain.

[0072] <Action and effect> As described above, the grains are crushed between the electrode rollers 31, 32 by the rotation of the pair of electrode rollers 31, 32, and in a state in which the crushed grains (crushed grains) are sandwiched between the electrode rollers 31, 32, a signal corresponding to the electrical resistance value between the electrode rollers 31, 32 is output from the signal output unit 45. For example, if noise is mixed into the signal output from the signal output unit 45, the voltage value of the signal does not correspond to the electrical resistance value between the electrode rollers 31, 32, and therefore the moisture content contained in the grains cannot be correctly obtained from the voltage value of the signal.

[0073] Therefore, an averaging process is performed on the voltage value of the signal output from the signal output unit 45, and the moisture content corresponding to the voltage value averaged by the averaging process is obtained using the paddy / wheat calibration curve 46 or the barley calibration curve 47. Therefore, even if noise is mixed into the signal output from the signal output unit 45, the influence of the noise can be eliminated by the averaging process. However, if a calibration curve created without considering the averaging process is used to obtain the moisture content from the voltage value, the voltage value changes before and after the averaging process, and an error due to the change may appear in the moisture content. The paddy / wheat calibration curve 46 is created by performing an averaging process using an averaging algorithm on the voltage value of the signal output from the signal output unit 45 through experiments, and then correlating the voltage value averaged by the averaging process with the known moisture content of the grain. Also, the barley calibration curve 47 is created through experiments by performing averaging processing using a peak algorithm on the voltage values ​​of the signal output from the signal output unit 45, and correlating the voltage value averaged by the averaging processing with the known moisture content of the grain. Therefore, the voltage value averaged by the averaging processing can be accurately converted into the moisture content contained in the grain. Therefore, the moisture content of the grain can be detected with high accuracy.

[0074] Furthermore, instead of a method in which a single kernel is squeezed between a pair of electrode rollers 31, 32 and a signal corresponding to the electrical resistance value between the electrode rollers 31, 32 is obtained, kernels stored in the sensor case 21 are squeezed between a pair of electrode rollers 31, 32 and a signal corresponding to the electrical resistance value between the electrode rollers 31, 32 is output. Therefore, even if foreign matter such as straw or insects gets mixed in with the kernels in the sensor case 21, the effect of the foreign matter on the change in the electrical resistance value is small. Therefore, the amount of moisture contained in the kernels can be detected with higher accuracy.

[0075] Furthermore, the period during which a signal is stably output from the signal output unit 45 is set to a fixed period, and the signal output from the signal output unit 45 during that fixed period is used to obtain the moisture content, thereby stabilizing the voltage value averaged by the averaging process, and enabling the moisture content in the grain to be detected with higher accuracy.

[0076] Furthermore, in the averaging process using the peak algorithm, the peak value of the voltage is obtained at regular intervals (for example, every second). This makes it possible to obtain the voltage value of a signal corresponding to the electrical resistance value between the electrode rollers 31 and 32 when the grains are being crushed between the electrode rollers 31 and 32. As a result, the moisture content in the grains can be detected with even greater accuracy.

[0077] Furthermore, the electrical resistance value between the electrode rollers 31, 32 changes depending on the temperature of the grains crushed between the electrode rollers 31, 32. That is, as the temperature of the grains crushed between the electrode rollers 31, 32 increases, the electrical resistance value between the electrode rollers 31, 32 decreases. Therefore, the voltage value of the signal output from the signal output unit 45 or the moisture content acquired by the moisture content acquisition unit 43 is corrected according to the temperature of the grain. As a result, the moisture content contained in the grain can be detected with high accuracy.

[0078] <Modification> Although one embodiment of the present invention has been described above, the present invention can be embodied in other forms.

[0079] For example, in the above embodiment, the correction unit 44 of the ECU 41 shifts the paddy-wheat calibration curve 46 and the barley calibration curve 47 by a shift amount according to the grain temperature, and the voltage value averaged by the averaging process is converted to a moisture content using the paddy-wheat calibration curve 46 or the barley calibration curve 47 after the shift, so that the voltage value averaged by the averaging process or the moisture content obtained by converting the voltage value is corrected according to the grain temperature. Without being limited to this, the voltage value averaged by the averaging process may be converted to a moisture content using the paddy-wheat calibration curve 46 or the barley calibration curve 47, and the converted moisture content value may be corrected according to the grain temperature. Furthermore, the voltage value averaged by the averaging process may be corrected according to the grain temperature, and the corrected voltage value may be converted to a moisture content using the paddy-wheat calibration curve 46 or the barley calibration curve 47.

[0080] In addition, in the above-described embodiment, a temperature sensor 48 is provided in the moisture sensor 16 and the temperature of the grain is detected by the temperature sensor 48, but a temperature sensor may be provided in the grain tank 5 and the temperature of the grain may be detected by the temperature sensor.

[0081] Furthermore, a temperature sensor for detecting the substrate temperature of the ECU 41 may be provided, and the voltage value averaged by the averaging process or the moisture amount obtained by converting the voltage value may be corrected in accordance with the substrate temperature.

[0082] In addition, various design modifications can be made to the above-described configuration within the scope of the claims. [Explanation of symbols]

[0083] 16: Moisture sensor (moisture detection device) 31, 32: Electrode roller 35: Motor 41: ECU (moisture content detector) 42: Drive control unit 43: Moisture content acquisition part 44: Correction section 45: Signal output section 46: Calibration curve for rice and wheat 47: Barley calibration curve 48: Temperature sensor

Claims

1. An apparatus for detecting the moisture content of grains, comprising: A case for receiving the grain; A pair of electrode rollers arranged adjacent to each other within the case; A motor that rotates the electrode roller; a drive control unit that rotates the pair of electrode rollers by the motor; a signal output unit that outputs a signal according to an electrical resistance value between the electrode rollers when grains are crushed between the electrode rollers by rotation of the pair of electrode rollers; a moisture content acquiring unit that acquires a moisture content corresponding to a voltage value of the signal output from the signal output unit by using a calibration curve that has been created in advance; a correction unit that corrects the voltage value of the signal output from the signal output unit or the moisture content acquired by the moisture content acquisition unit in accordance with a temperature of the grain, The drive control unit continuously rotates the pair of electrode rollers by the motor while grains are stored in the case, the moisture content acquisition unit performs an averaging process of averaging a voltage value of the signal output from the signal output unit for a certain period during rotation of the pair of electrode rollers, and acquires a moisture content corresponding to the averaged voltage value using the calibration curve; A moisture content detection device in which, when the size of the grain is a predetermined small size, in the averaging process, the moisture content acquisition unit samples the voltage value of the signal output from the signal output unit, calculates a sample average value and standard deviation from the sampled values, and calculates an averaged voltage value by performing a calculation according to an arithmetic formula using the sample average value and the standard deviation.

2. 2. The moisture content detection device of claim 1, wherein when the size of the grain is a predetermined large size, in the averaging process, the moisture content acquisition unit acquires peak values ​​of the voltage value of the signal output from the signal output unit at regular intervals, and calculates the average value of the acquired peak values ​​as the averaged voltage value.

3. An apparatus for detecting the moisture content of grains, comprising: A case for receiving the grain; A pair of electrode rollers arranged adjacent to each other within the case; A motor that rotates the electrode roller; a drive control unit that rotates the pair of electrode rollers by the motor; a signal output unit that outputs a signal according to an electrical resistance value between the electrode rollers when grains are crushed between the electrode rollers by rotation of the pair of electrode rollers; a moisture content acquiring unit that acquires a moisture content corresponding to a voltage value of the signal output from the signal output unit by using a calibration curve that has been created in advance; a correction unit that corrects the voltage value of the signal output from the signal output unit or the moisture content acquired by the moisture content acquisition unit in accordance with a temperature of the grain, the moisture content acquisition unit performs an averaging process for averaging a voltage value of the signal output from the signal output unit, and acquires a moisture content corresponding to the averaged voltage value using the calibration curve; A moisture content detection device in which, when the size of the grain is a predetermined large size, in the averaging process, the moisture content acquisition unit acquires the peak value of the voltage value of the signal output from the signal output unit at regular intervals, and calculates the average value of the acquired peak values ​​as the averaged voltage value.

4. The drive control unit continuously rotates the pair of electrode rollers by the motor while grains are stored in the case, The moisture content detection device according to claim 3 , wherein the moisture content acquisition section uses the signal output from the signal output section for a fixed period during rotation of the pair of electrode rollers to acquire the moisture content.

5. 5. The moisture content detection device according to claim 1, wherein the calibration curve is created by performing an averaging process having the same content as the averaging process performed by the moisture content acquisition section.

6. a temperature sensor for detecting a temperature of the kernels received in the case; A moisture content detection device as described in any one of claims 1 to 5, wherein the correction unit corrects the voltage value of the signal output from the signal output unit or the moisture content acquired by the moisture content acquisition unit in accordance with the temperature detected by the temperature sensor.

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