阅读说明：本技术 联合收割机的粮箱谷物堆积高度测量装置 (Grain box grain stacking height measuring device of combine harvester ) 是由 张方明 于 2019-11-22 设计创作，主要内容包括：一种联合收割机的粮箱谷物堆积高度检测装置,3只平板电容器构成测量传感器,每只电容器的极板间距、宽度相同,谷物填充量传感器竖立于粮箱的内壁,谷物参考传感器平立于粮箱内的底部,粉尘传感器平立于粮箱内的顶部,每只传感器通过同轴电缆与测量ECU电连接。3只固定电容元件分别与3只平板电容器构建了3组桥臂,信号发生电路产生的正弦信号、三组桥臂的分压信号通过两只独立的四路模拟开关,输入到峰峰值检测电路和平均值转换电路,由单片机通过A/D变换获得四路信号的峰峰值、平均值,计算出实时环境下的谷物与粉尘的介电常数,从而计算出谷物的堆积高度。本装置不仅可以连续测量,而且够适应不同含水量的谷物和粉尘环境的测量。(A grain stacking height detection device for a grain tank of a combine harvester is characterized in that 3 flat capacitors form measuring sensors, the distance and the width of the pole plates of each capacitor are the same, a grain filling quantity sensor is vertically arranged on the inner wall of the grain tank, a grain reference sensor is horizontally arranged at the bottom in the grain tank, a dust sensor is horizontally arranged at the top in the grain tank, and each sensor is electrically connected with a measuring ECU (electronic control unit) through a coaxial cable. 3 fixed capacitance elements and 3 flat capacitors respectively construct 3 groups of bridge arms, sinusoidal signals generated by a signal generation circuit and partial pressure signals of three groups of bridge arms are input into a peak-to-peak value detection circuit and an average value conversion circuit through two independent four-way analog switches, a singlechip acquires peak-to-peak values and average values of the four-way signals through A/D conversion, and dielectric constants of grains and dust in a real-time environment are calculated, so that the accumulation height of the grains is calculated. This device not only can continuous measurement, enough adapts to the measurement of the cereal of different water contents and dust environment moreover.)

1. The utility model provides a grain tank grain pile height measuring device of combine which characterized in that: the grain stacking height measuring device is composed of 3 parallel plate capacitors, the plate distance and width of each capacitor are the same, wherein the first capacitor is a grain filling sensor C_gThe pole plate is vertically arranged on the inner wall of the grain tank opposite to the outlet of the elevator, and the length of the pole plate is equal to the distance between the bottom of the grain tank and the outlet of the elevator; the second capacitor being a grain reference sensor C_rThe grain bin is horizontally arranged at the bottom of the grain bin and spans between the brackets at the bottom of the grain bin; the third capacitor being a dust sensor C_dIt is horizontally arranged on the top of the grain tank, and the length of the polar plate is equal to that of the grain reference sensor C_rLength of the plate; each sensor is electrically connected with the measurement ECU through a coaxial cable.

2. The combine harvester grain bin grain bulk height measuring device of claim 1, wherein: 3 pure capacitive bridge arms connected in parallel are constructed in the measurement ECU: capacitor C₁And a grain filling amount sensor C_gFormed bridge arm and capacitor C₂And a grain reference sensor C_rFormed bridge arm, and capacitor C₃And dust sensor C_dA bridge arm is formed; capacitor C₁Capacitor C₂And a capacitor C₃Are capacitive components whose capacitance values are selected such that: filling amount sensor C for grain_gAnd a grain reference sensor C_rRespectively submerging in cereals, adjusting capacitance C₁And a capacitor C₂Is selected such that C₁＝C_g，C₂＝C_r(ii) a Adjusting the capacitance C in a dust-free environment₃Is selected such that C₃＝C_d。

3. The combine harvester grain bin grain bulk height measuring device of claim 1, wherein: sinusoidal signals generated by the RLC sine wave signal generating circuit and voltage division signals of three groups of bridge arms are respectively and electrically connected with S1-S4 pins of two independent TMUX1104 four-way analog switches, namely, each signal is simultaneously connected to a same-name pin of the TMUX1104 four-way analog switch, a D pin of a first TMUX1104 four-way analog switch is electrically connected with a Vin pin of AN LTC5507 peak-to-peak value detection circuit, a D pin of a second TMUX1104 four-way analog switch is electrically connected with a Vin pin of AN AD736 average value conversion circuit, a Vo pin of the LTC5507 peak-to-peak value detection circuit is electrically connected with AN AN0 pin of a PIC18F25K80 singlechip, a Vo pin of the AD736 average value conversion circuit is electrically connected with AN AN1 pin of the PIC18F25K80 singlechip, RC0, RC1 and TMRC 2 of the PIC18F25K80 singlechip are respectively and electrically connected with EN, A1 and A0 of the first TMUX1104 four-way analog switch, and the RC 583948 and the second RC4 of the singlechip are respectively and electrically connected with AN EN 5839 0A of the PIC 1104.

4. The combine harvester grain bin grain bulk height measuring device of claim 1, wherein: after the measurement ECU is electrified, RA and RC ports of a PIC18F25K80 singlechip are initialized, two four-way analog switches are all in a disconnected state, then a TIMER TIMER0, analog-to-digital A/D conversion and a CAN communication register are sequentially initialized, a time relay T0 is constructed, and the TIMER and CAN communication interruption function is started; the program runs in a cyclic scanning manner: when the time relay T0 is up, the first TMUX1104 four-way analog switch is enabled, the first analog switch is closed, A/D conversion is started, and the peak-peak value U of the sinusoidal signal generated by the RLC sinusoidal signal generating circuit is read out from the AN0 port_ippThen sequentially reading out the grain filling amount sensor C_gGrain reference sensor C_rAnd dust sensor C_dThe voltage division values U generated in the respective bridge arms_gpp、U_rpp、U_dpp(ii) a The first TMUX1104 four-way analog switch is closed and then theA second TMUX1104 four-way analog switch is closed, A/D conversion is started, and the average value U of sinusoidal signals generated by the RLC sinusoidal signal generating circuit is read out from AN AN1 port_irmsThen sequentially reading out the grain filling amount sensor C_gGrain reference sensor C_rAnd dust sensor C_dThe voltage division values U generated in the respective bridge arms_grms、U_rrms、U_drms(ii) a The current grain stacking height can be calculated according to both peak-to-peak measurement and mean measurement:

in the formula, x_pp: current pile height, x, obtained from peak-to-peak measurements_rms: the current stack height, L, obtained is measured from the mean value₁: grain filling amount sensor C_gLength of the pole plate, L₂: grain reference sensor C_rLength of the plate; when the PIC18F25K80 singlechip generates CAN interruption, the time constant of the time relay T0 is modified according to the instruction, namely the frequency of data output is changed.

Technical Field

The invention belongs to the field of agricultural machinery, and particularly relates to a sensor technology of a combine harvester.

Background

Harvesters in paddy fields in south of China are usually provided with grain tanks, the capacity of which is about 1000-1500 liters, and the grain tanks are used for temporarily storing grains, and the temporarily stored grains are usually unloaded to a transport vehicle through a flood dragon at the ground. A conventional grain bin has a bin alarm sensor disposed therein, and the machine sounds a bin full alarm when the grain stack reaches this level, generally speaking, the capacity of the bin is sufficient to contain one round trip of grain. However, due to the restriction of various factors such as co-production contract, paddy field management capacity and terrain in China, most paddy fields are not large in area, and one crop can not be filled with one box of grains after one harvest. At the moment, a driver can only rely on the glass observation window above the grain tank, and when the driver passes through the ground each time, if grains are piled up by more than seventy percent, the grains are unloaded, otherwise, the grains are continuously harvested. This shows that this grain tank warning sensor can not satisfy the actual demand in the production, needs novel sensor device that can reflect cereal pile height in real time.

There are a number of patents disclosing devices for measuring the level of particulate matter such as grain and coal using electrical measurement techniques. For example, "a continuous capacitance sensor" (chinese patent CN98110100.3) proposes a tubular capacitance sensor, but for grain particles, the mobility is much less than that of liquid, and it is difficult to reflect the actual grain filling amount in the grain bin. The "pressure type digital level sensor and its measuring method" (chinese patent CN200810054853.8) proposes a sensor structure in which piezoelectric ceramic plates are densely arranged on a rod-shaped body along a longitudinal axis, so that the piezoelectric ceramic under the level can generate weak electrical signals, which are converted into high or low level after signal amplification and shaping, thereby measuring the level. The method needs a large number of piezoelectric ceramic pieces and matched hardware detection components, and the cost of a measuring circuit is high. "a real-time yield measurement system and method of grain combine" (chinese patent 201811092523.8) uses a capacitive level sensor whose measuring electrodes are inserted into the interior of the grain bin to measure the height of the grain. However, freshly harvested grain has a large moisture content difference, only one electrode, requires additional calibration, and is a distance away from the production application.

Disclosure of Invention

In order to overcome the defects of the existing grain bin stacking height sensing device, the invention provides an improved sensor device. The device not only can measure the grain pile height of grain tank in succession, can adapt to the measurement of the grain object of different moisture content and dust environment moreover.

The technical scheme adopted by the invention for solving the technical problems is as follows: the grain stacking height measuring device is composed of 3 parallel plate capacitors, each capacitor has the same plate spacing and width, and the first capacitorThe device being a grain filling quantity sensor C_gThe pole plate is vertically arranged on the inner wall of the grain tank opposite to the outlet of the elevator, and the length of the pole plate is equal to the distance between the bottom of the grain tank and the outlet of the elevator; the second capacitor being a grain reference sensor C_rThe grain bin is horizontally arranged at the bottom of the grain bin and spans between the brackets at the bottom of the grain bin; the third capacitor being a dust sensor C_dThe plate is horizontally arranged on the top in the grain bin, and the length of the plate is equal to that of the plate of the grain reference sensor Cr. When the combine is operating, the grain reference sensor C_rThe space between the plates will be filled first and quickly; thereafter, with continued harvesting, a grain fill sensor C_gThe space between the polar plates is gradually filled, and the filling degree of the grains between the polar plates is consistent with the stacking height of the grains in the grain tank; dust sensor C_dIs always in the environment of dust flying. At any moment, the dielectric constants of the grains and dust are larger than 1, and the capacitance value of the grain filling quantity sensor Cg reflects the current grain stacking height in the grain bin. Each sensor is electrically connected with a measurement ECU through a coaxial cable, and the measurement ECU is fixed at the top corner inside the grain tank.

The measurement ECU has 3 BNC ports, each port corresponding to a plate capacitor. 3 pure capacitive bridge arms connected in parallel are constructed in the measurement ECU: capacitor C₁And a grain filling amount sensor C_gFormed bridge arm and capacitor C₂And a grain reference sensor C_rFormed bridge arm, and capacitor C₃And dust sensor C_dThe bridge arm is formed. Capacitor C₁Capacitor C₂And a capacitor C₃Are capacitive components whose capacitance values are selected such that: filling amount sensor C for grain_gAnd a grain reference sensor C_rRespectively submerging in cereals, adjusting capacitance C₁And a capacitor C₂Is selected such that C₁＝C_g，C₂＝C_r(ii) a Adjusting the capacitance C in a dust-free environment₃Is selected such that C₃＝C_d. Although the moisture content of freshly harvested grain is constantly changing, the different varieties of grain also contribute to their dielectric propertiesThe constants being different, but the capacitance C₁Capacitor C₂And a capacitor C₃Once determined, it is fixed in hardware without affecting the results of the measurements. The measurement ECU also has a power supply communication port which CAN be accessed with 9-36V direct current and a CAN network.

The measurement ECU also comprises an RLC sine wave signal generating circuit, a TMUX1104 four-way analog switch, an LTC5507 peak-to-peak value detection circuit, an AD736 average value conversion circuit, a PIC18F25K80 single chip microcomputer and a TJA1050 communication circuit. Sinusoidal signals generated by AN RLC sine wave signal generating circuit and voltage division signals of three groups of bridge arms are respectively and electrically connected with S1-S4 pins of two independent TMUX1104 four-way analog switches, namely, each signal is simultaneously connected to a same-name pin of the TMUX1104 four-way analog switch, a D pin of a first TMUX1104 four-way analog switch is electrically connected with a Vin pin of AN LTC5507 peak-to-peak value detection circuit, a D pin of a second TMUX1104 four-way analog switch is electrically connected with a Vin pin of AN AD736 average value conversion circuit, a Vo pin of the LTC5507 peak-to-peak value detection circuit is electrically connected with AN AN0 pin of a PIC18F25K80 singlechip, a Vo pin of the AD736 average value conversion circuit is electrically connected with AN AN1 pin of the PIC18F25K80 singlechip, RC0, RC1 and TMRC 2 of the PIC18F25K80 singlechip are respectively and electrically connected with EN, A1 and A0 of the first TMUX1104 four-way analog switch, RC 5A 23 and CANTN 23 of the singlechip are respectively and electrically connected with AN RC 5A 5 of the PIC 1104, The CANRX pin is electrically connected with TXD and RXD pins of a TJA1050 communication circuit, and CANH and CANL pins of the TJA1050 communication circuit are electrically connected with a CAN port of the measurement ECU.

After the measurement ECU is electrified, RA and RC ports of a PIC18F25K80 singlechip are initialized, two four-way analog switches are all in an off state, then a TIMER TIMER0, analog-to-digital A/D conversion and a CAN communication register are sequentially initialized, a time relay T0 is constructed, and the TIMER and CAN communication interruption function is started. The program runs in a cyclic scanning manner: when the time relay T0 is up, the first TMUX1104 four-way analog switch is enabled, the first analog switch is closed, A/D conversion is started, and the peak-peak value U of the sinusoidal signal generated by the RLC sinusoidal signal generating circuit is read out from the AN0 port_ippThen reading out the grains in sequenceFilling amount sensor C_gGrain reference sensor C_rAnd dust sensor C_dThe voltage division values U generated in the respective bridge arms_gpp、U_rpp、U_dpp. Closing the first TMUX1104 four-way analog switch, enabling the second TMUX1104 four-way analog switch, closing the first analog switch, starting A/D conversion, and reading out the average value U of sinusoidal signals generated by the RLC sinusoidal signal generating circuit from AN AN1 port_irmsThen sequentially reading out the grain filling amount sensor C_gGrain reference sensor C_rAnd dust sensor C_dThe voltage division values U generated in the respective bridge arms_grms、U_rrms、U_drms. Here, the grain filling amount sensor C is considered_gThe dust-proof capacitor is formed by connecting a capacitor filled with grains and a capacitor filled with dust in parallel, and has the following characteristics without loss of generality:

wherein the content of the first and second substances,

in the formula, epsilon₀: electrical conductivity of air,. epsilon_g: conductivity of the grain,. epsilon_d: conductivity of dust

W: width of the pole plate, L₁: grain filling amount sensor C_gPlate length of (a), x: the current filling height, d, is the gap between the plates.

Reference sensor for grain C_rThe method comprises the following steps:

in the formula, L₂: grain reference sensor C_rThe length of the plate.

For dust sensor C_dThe method comprises the following steps:

from the equations (2) and (3), the dielectric constant ε under real-time conditions can be calculated₀ε_gAnd ε₀ε_dIn the formula (1), the following can be obtained:

since the measuring device has already read out U_ipp、U_gpp、U_rpp、U_dppAnd U_irms、U_grms、U_rrms、U_drms，C₁,C₂,C₃Are known values and therefore equation (4) can calculate a measure for grain bulk height based on readings of peak-to-peak and mean values, respectively.

When the PIC18F25K80 singlechip generates CAN interruption, the time constant of the time relay T0 is modified according to the instruction, namely the frequency of data output is changed.

The invention has the advantages that the stacking height of the grains in the grain tank of the harvester can be continuously measured, and the method can be suitable for measuring grain objects with different water contents and impurity contents. The mechanism can be used for grain harvesters and improves the digitalization degree of agricultural machinery.