Variable spraying device and method for tail gun of translational sprinkler suitable for non-square fields

Abstract

The present invention discloses a variable spraying device and method of a tail gun of a translational sprinkler suitable for non-square fields. The specific process is as follows: step 1, determining the relationship between the working pressure of the tail gun and the flow rate and the range; step 2, according to the shape of the controlled spraying plot, taking the tail gun working pressure not less than 0.2MPa as the benchmark, obtaining the maximum and minimum values ​​of the tail gun range; step 3, establishing the relationship between the motor power supply frequency of the AC booster pump and the tail gun range, and determining the change law of the motor power supply frequency over time during the mobile spraying process; step 4, obtaining the total spraying water volume and average sprinkler irrigation intensity of the tail gun, and determining the nozzle diameter of the tail gun; step 5, optimizing the water volume distribution in the tail gun spraying area. The method of the present invention solves the problem of terminal leakage when the translational sprinkler is spraying non-square fields such as trapezoidal fields.

Description

Technical Field

[0001] The invention belongs to the technical field of agricultural water-saving irrigation, and in particular relates to a variable spraying device of a tail gun of a translational sprinkler suitable for non-square fields, and also relates to a variable spraying method of a tail gun of a translational sprinkler suitable for non-square fields. Background Art

[0002] The translational sprinkler is a modern, efficient, water-saving irrigation equipment that is easy to operate mechanically and has a high level of automation. It integrates advanced technologies such as automatic control and precise navigation, and has significant advantages such as water-saving, labor-saving, and high efficiency. It is an important supporting equipment for the development of water-saving in agricultural irrigation and the promotion of increased grain production capacity, and is being used more and more widely in my country and the international market.

[0003] According to the area of ​​the controlled irrigation plot, the horizontal sprinkler machine selects different span lengths and span numbers, with the total span ranging from tens of meters to hundreds of meters. During the movement of the unit, different types of navigation technologies such as GPS or Beidou satellite navigation, trench navigation, and cable navigation can be used to ensure that the unit moves in a straight line. Therefore, the spraying area of ​​the horizontal sprinkler is generally square.

[0004] The nozzle type used in the translation sprinkler is generally a low-pressure refraction nozzle, including fixed sprinkler, rotary sprinkler, and oscillating spray disc. In actual operation, in order to increase the control area of ​​the unit and improve the unit's operating efficiency, tail guns are often added at both ends of the unit. In order to make the tail gun have a larger flow rate and spraying range, the working pressure of the tail gun is generally much higher than that of the low-pressure refraction nozzle, and a booster pump is required to pressurize the pipeline water for the second time. Since the working pressure and range of the tail gun remain constant during operation, the spraying control area of ​​the unit is still square.

[0005] Due to the inclination of farm roads or field roads during planning, non-square fields such as trapezoids often appear when dividing fields. At this time, the use of translational sprinklers for spraying cannot achieve full coverage of the fields, and areas that are easily missed on one or both sides of the field are prone to be missed. In order to solve the above problem and achieve full-area spraying, variable spraying technology is required.

[0006] The current mobile sprinkler variable spraying technology mainly targets the low-pressure refractive sprinkler in the middle, and uses solenoid valves to control the opening or closing of the sprinkler, or uses electric valves to adjust different valve openings to control the amount of irrigation. The Chinese invention patent with application number 201811319461.X discloses a circular sprinkler nozzle configuration method based on pulse width modulation variable sprinkler irrigation, and proposes to group the sprinklers according to the optimal duty cycle control range of the PWM solenoid valve, and calculate the nozzle size used for each group of sprinklers when the flow demand is met, so as to achieve the goal of mobile precision spraying; the Chinese invention patent with application number 201510266836.0 discloses a variable irrigation control method, device and system based on a large sprinkler, and proposes a variable irrigation technology that automatically identifies partitions and adjusts the number of sprinkler workings or changes the water spraying amount to achieve partitioned sprinkler irrigation. However, the implementation of the above patents is aimed at regulating the low-pressure refractive nozzles on the main span of the mobile sprinkler irrigation machinery, but when the translational sprinkler irrigation machine is spraying on non-square fields such as trapezoidal fields, there is still a problem of end leakage. Summary of the invention

[0007] The purpose of the present invention is to provide a variable spraying device for the tail gun of a translational sprinkler suitable for non-square fields, which solves the problem of end leakage when the translational sprinkler is spraying on non-square fields such as trapezoidal fields.

[0008] Another object of the present invention is to provide a variable spraying method of a tail gun of a translational sprinkler suitable for non-square fields.

[0009] The technical solution adopted by the present invention is a variable spraying device for the tail gun of a translational sprinkler machine suitable for non-square fields, including a water supply main pipe, the water supply main pipe is connected to one end of a water supply branch pipe, the other end of the water supply branch pipe is connected to the tail gun, an electric valve is arranged on the water supply branch pipe and at one end close to the water supply main pipe, an AC booster pump is arranged on the water supply branch pipe and at one end close to the tail gun, the AC booster pump is connected to a frequency converter, the frequency converter is connected to a PLC controller, and the PLC controller and the electric valve are both connected to an interactive control end.

[0010] Another technical solution adopted by the present invention is a variable spraying method of a tail gun of a translational sprinkler suitable for non-square fields, which adopts a variable spraying device of a tail gun of a translational sprinkler suitable for non-square fields, and is specifically implemented according to the following steps:

[0011] Step 1, determine the relationship between the working pressure of the tail gun and the flow rate and range;

[0012] Step 2, according to the shape of the spraying plot, taking the tail gun working pressure not less than 0.2MPa as the benchmark, obtain the maximum and minimum values ​​of the tail gun range;

[0013] Step 3, establishing the relationship between the motor power supply frequency of the AC booster pump and the tail gun range, and determining the change pattern of the motor power supply frequency over time during the mobile spraying process;

[0014] Step 4, obtaining the total water volume and average sprinkler intensity of the tail gun, and determining the nozzle diameter of the tail gun;

[0015] Step 5: Optimize the water distribution within the tail gun spraying area.

[0016] The present invention is also characterized in that:

[0017] The specific process of step 1 is:

[0018] According to the model and nozzle diameter of the tail gun, determine the flow rate of the tail gun at different working pressures from the product manual of the tail gun or through actual measurement, and fit the working pressure and flow rate relationship of the tail gun:

[0019] Q = h (P) (1)

[0020] In formula (1), Q is the flow rate of the tail gun, and P is the working pressure of the tail gun;

[0021] According to the model of the tail gun, the nozzle diameter and the installation height of the tail gun at the end of the translational sprinkler, the range of the tail gun under different working pressures is determined through actual measurement, and the relationship between the working pressure and the range of the tail gun is established:

[0022] R = g(P) (2)

[0023] In formula (2), R is the range of the tail gun, and P is the working pressure of the tail gun.

[0024] The specific process of step 2 is:

[0025] Assume that the spraying area has two parallel sides of different lengths, the longer side is B 1 , the short side is B 2 , the span length of the inner span where the tail gun is located is L;

[0026] The maximum range of the tail gun is R 1 for:

[0027] R 1 =B 1 -L (3)

[0028] The minimum range of the tail gun is R 2 for:

[0029] R 2 =B 2 -L (4)

[0030] Set the maximum range R 1 Substituting into formula (2), we get the maximum range R1 Corresponding working pressure P 1 ; Set the minimum range R 2 Substituting into formula (2), we get the minimum range R 2 Corresponding working pressure P 2 , P 2 >0.2MPa;

[0031] If the working pressure P 2 When the pressure is less than 0.2MPa, the span length of the inner span where the tail gun is located is adjusted to L-ΔL, where the initial value of ΔL is 1m, and the step interval is 1m. At this time, the minimum range R 2 ， =B 2 -L+ΔL, until the minimum range R 2 ， Corresponding working pressure P 2 ， is greater than 0.2Mpa, thus obtaining the adjusted span length of the inner span where the tail gun is located. Substituting this into formula (3) and formula (4), the maximum and minimum values ​​of the tail gun's range can be obtained.

[0032] The specific process of step 3 is:

[0033] For AC asynchronous motors, the relationship between the supply frequency and the motor speed is as follows:

[0034] (5)

[0035] In formula (5), n is the motor speed, f is the power supply frequency, p is the number of pole pairs of the motor, and s is the slip rate of the AC asynchronous motor, where p and s are both constant and known;

[0036] The relationship between the power supply frequency of the AC asynchronous motor and the working pressure of the tail gun is determined by actual measurement, namely:

[0037] f = y(P) (6)

[0038] In formula (6), f is the power supply frequency, P is the working pressure of the tail gun;

[0039] Combined with formula (2), the relationship between the AC asynchronous motor power supply frequency and the tail gun range is obtained, namely:

[0040] f = j (R) (7)

[0041] Substitute the maximum and minimum values ​​of the tail gun range obtained in step 2 into formula (7) to obtain the power supply frequency f corresponding to the maximum value of the tail gun range: 1 , the power supply frequency f corresponding to the maximum value of the tail gun range 2 , then the range of the AC asynchronous motor power supply frequency f is (f 1, f 2 );

[0042] By default, as the horizontal sprinkler moves in the field, the AC asynchronous motor power supply frequency f changes linearly. When the horizontal sprinkler moves from the long side to the short side of the spraying plot, the AC asynchronous motor power supply frequency f changes with time as follows:

[0043] (8)

[0044] In formula (8), v is the travel speed of the translational sprinkler, D is the total distance moved by the translational sprinkler in the travel direction, and t is the travel time of the translational sprinkler;

[0045] When the translation sprinkler moves from the short side to the long side of the spraying plot, the change law of the AC asynchronous motor power supply frequency f over time is:

[0046] (9).

[0047] The specific process of step 4 is:

[0048] According to the variation law of the motor power supply frequency over time during mobile spraying and formula (6), the variation law of the working pressure of the tail gun over time is obtained. Combined with formula (1), the variation law of the flow rate of the tail gun over time is obtained, that is:

[0049] Q = w (t) (10)

[0050] The total amount of water sprayed by the tail gun is:

[0051] (11)

[0052] The average sprinkler intensity within the spraying area of ​​the tail gun is:

[0053] (12)

[0054] In formula (12), S 尾 The area to be sprayed by the tail gun (3);

[0055] The total water volume of the inner span low pressure refraction nozzle is:

[0056] (13)

[0057] In formula (13), i is the number of the low-pressure refractive nozzle, N is the total number of low-pressure refractive nozzles, and q i is the flow rate of the i-th low-pressure refraction nozzle;

[0058] The average irrigation intensity of the inner span low-pressure refraction sprinkler spray area is:

[0059] (14)

[0060] In formula (14), The area that the low-pressure refraction nozzle should spray for the inner span;

[0061] Compare and , judge the matching degree between the selected tail gun flow rate and the inner span low pressure refraction nozzle flow rate, calculate the matching deviation coefficient δ, then:

[0062] = *100% (15)

[0063] When -10%< When <10%, it means that the flow rate of the tail gun is highly matched with the flow rate of the inner span low-pressure refraction nozzle, and go to step 5;

[0064] when <-10%, it means that the flow rate of the selected tail gun is too small, then you need to select a nozzle with a larger diameter than the current one to replace the current nozzle, and repeat steps 1-4 until -10%< <10% and go to step 5;

[0065] when >10%, it means that the flow rate of the selected tail gun is too large, and you need to select a nozzle with a smaller diameter than the current one to replace the current nozzle, and repeat steps 1-4 until -10%< If <10%, proceed to step 5.

[0066] The specific process of step 5 is:

[0067] The required spraying area of ​​the tail gun is divided into m units with a spacing of 30m in the direction of travel of the translation sprinkler. Each unit is divided into trapezoids. For the jth unit, the time before and after the translation sprinkler passes through the unit is t j and t j+1 The lengths of the upper and lower bases of the trapezoid corresponding to this unit are R j and R j+1 , then the amount of water sprayed by the tail gun when the horizontal sprinkler passes through the unit for:

[0068] (16)

[0069] Total area sprayed by the unit for:

[0070] (17)

[0071] In formula (17), d is the spacing distance along the moving direction of the translation sprinkler irrigation unit;

[0072] Then the average sprinkler intensity of the tail gun in the jth unit is:

[0073] (18)

[0074] In order to make the water distribution in the tail gun spraying area uniform, the average sprinkler intensity in different units should be consistent with the average sprinkler intensity of the entire spraying area, and the flow compensation coefficient in each unit should be calculated. :

[0075] ×100% (19)

[0076] The flow compensation in each unit is completed by adjusting the opening of the electric valve on the water supply branch pipe. The relationship between the different working pressures of the tail gun and the flow rate of the water supply branch pipe, and the relationship between the different openings of the electric valve and the flow rate of the water supply branch pipe are obtained through actual measurement. According to the relationship between the working pressure and the flow rate, and the relationship between different openings and the flow rate, the relationship between the flow compensation coefficient and the opening of the electric valve is established, that is:

[0077] =s(Ψ)(20)

[0078] In formula (20), is the flow compensation coefficient, Ψ is the opening of the electric valve;

[0079] When the flow compensation coefficient ε is less than 0, the opening of the electric valve is reduced, and when the flow compensation coefficient ε is greater than 0, the opening of the electric valve is increased.

[0080] The beneficial effects of the present invention are:

[0081] (1) The variable spraying method of the tail gun of a translational sprinkler machine is suitable for non-square fields. Dynamic water pressure spraying is achieved based on frequency conversion control, thereby adjusting the effective spraying range of the tail gun to match the contour line of the plot, achieving full spraying coverage of non-standard plots such as trapezoidal plots, which is an effective supplement to the existing translational sprinkler machine that can only spray and control standard square plots;

[0082] (2) The variable spraying method of the tail gun of the translational sprinkler is suitable for non-square fields. The variable spraying design of the tail gun takes into account the matching of the sprinkler intensity of the inner span low-pressure refraction sprinkler, avoids surface water accumulation or runoff caused by excessive sprinkler intensity on one side, and facilitates the unified control of the travel speed of the translational sprinkler;

[0083] (3) The variable spraying device of the tail gun of the translatory sprinkler of the present invention is suitable for non-square fields. The relevant operations can be performed through the local control panel, and remote control can be achieved through the cloud platform and the remote control terminal (mobile phone, computer, etc.), which is easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0084] Figure 1 It is a structural schematic diagram of a variable spraying device of a tail gun of a translational sprinkler machine suitable for non-square fields according to the present invention;

[0085] Figure 2 It is a schematic diagram of the variable spraying of the tail gun in the variable spraying method of the translation type sprinkler irrigation machine suitable for non-square fields of the present invention;

[0086] Figure 3 This is a schematic diagram of the change of the power supply frequency of the AC asynchronous motor in different travel directions in Example 3 of the present invention;

[0087] Figure 4 This is a schematic diagram of the division of the spraying area required for the tail gun in Example 3 of the present invention;

[0088] Figure 5 Schematic diagram of electric valve opening adjustment in Example 3 of the present invention.

[0089] In the figure, 1. Water supply main pipe, 2. Water supply branch pipe, 3. Tail gun, 4. AC booster pump, 5. Frequency converter, 6. PLC controller, 7. Electric valve, 8. Interactive control terminal. DETAILED DESCRIPTION

[0090] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0091] Example 1

[0092] The invention is suitable for a variable spraying device of the tail gun of a translational sprinkler irrigation machine for non-square fields, such as Figure 1 As shown, it includes a water supply main pipe 1, which is an existing pipeline on the translational sprinkler. The water supply main pipe 1 is connected to one end of the water supply branch pipe 2, and the other end of the water supply branch pipe 2 is connected to the tail gun 3. An electric valve 7 is arranged on the water supply branch pipe 2 and close to the water supply main pipe 1. An AC booster pump 4 is arranged on the water supply branch pipe 2 and close to the tail gun 3. The AC booster pump 4 is connected to a frequency converter 5, and the frequency converter 5 is connected to a PLC controller 6. The PLC controller 6 and the electric valve 7 are all connected to an interactive control terminal 8. The tail gun 3 is arranged at both ends of the translational sprinkler, and the AC booster pump 4 is equipped with an AC asynchronous motor.

[0093] Among them, the interactive control terminal 8 is used to adjust the power supply frequency change law of the AC asynchronous motor supporting the AC booster pump 4 and to adjust the opening of the electric valve 7; the interactive control terminal 8 can perform related operations through the local control panel, and can also realize remote control through the cloud platform and the remote control terminal (mobile phone, computer, etc.).

[0094] The PLC controller 6 is used to receive information input by the interactive control terminal 8, and transmit the received information to the frequency converter 5 to adjust the power supply frequency. Specifically, the analog output module of the PLC controller 6 is used to output a 4~20mA current signal as the analog input signal of the frequency converter 5, thereby controlling the output frequency of the frequency converter 5.

[0095] The frequency converter 5 is used to adjust the power supply frequency of the AC asynchronous motor matched with the AC booster pump 4.

[0096] Example 2

[0097] The variable spraying method of the tail gun of a translational sprinkler machine suitable for non-square fields of the present invention adopts the variable spraying device of the tail gun of the translational sprinkler machine suitable for non-square fields, and is specifically implemented according to the following steps:

[0098] Step 1, determining the relationship between the working pressure of the tail gun 3 and the flow rate and range;

[0099] The specific process of step 1 is: according to the model and nozzle diameter of the tail gun 3, the flow rate of the tail gun 3 under different working pressures is determined from the product manual of the tail gun 3 or through actual measurement, and the working pressure and flow rate relationship of the tail gun 3 is fitted:

[0100] Q = h (P) (1)

[0101] In formula (1), Q is the flow rate of the tail gun 3, and P is the working pressure of the tail gun 3;

[0102] According to the model of the tail gun 3, the nozzle diameter and the installation height of the tail gun 3 at the end of the translational sprinkler, the range of the tail gun 3 under different working pressures is determined by actual measurement, and the relationship between the working pressure and the range of the tail gun 3 is established:

[0103] R = g(P) (2)

[0104] In formula (2), R is the range of the tail gun 3, and P is the working pressure of the tail gun 3;

[0105] Step 2, according to the shape of the spraying plot, taking the working pressure of the tail gun 3 not less than 0.2MPa as the benchmark, obtain the maximum and minimum values ​​of the range of the tail gun 3;

[0106] The specific process of step 2 is:

[0107] like Figure 2As shown, it is assumed that the spraying plot has two parallel sides of different lengths, the longer side of which is B 1 , the short side is B 2 , the span length of the inner span where the tail gun 3 is located is L;

[0108] Then the maximum range of tail gun 3 is R 1 for:

[0109] R 1 =B 1 -L (3)

[0110] Then the minimum range of tail gun 3 is R 2 for:

[0111] R 2 =B 2 -L (4)

[0112] Set the maximum range R 1 Substituting into formula (2), we get the maximum range R 1 Corresponding working pressure P 1 ; Set the minimum range R 2 Substituting into formula (2), we get the minimum range R 2 Corresponding working pressure P 2 , P 2 >0.2MPa;

[0113] If the working pressure P 2 When the pressure is less than 0.2MPa, the span length of the inner span where the tail gun 3 is located is adjusted to L-ΔL, where the initial value of ΔL is 1m, and the step interval is 1m. At this time, the minimum range R 2 ， =B 2 -L+ΔL, until the minimum range R 2 ， Corresponding working pressure P 2 ， is greater than 0.2Mpa, thus obtaining the adjusted span length of the inner span where the tail gun 3 is located, and substituting it into formula (3) and formula (4), the maximum and minimum ranges of the tail gun 3 can be obtained;

[0114] Step 3, establishing the relationship between the motor power supply frequency of the AC booster pump 4 and the range of the tail gun 3, and determining the change pattern of the motor power supply frequency over time during the mobile spraying process;

[0115] The specific process of step 3 is:

[0116] For an AC booster pump 4, which includes an AC asynchronous motor, the relationship between the power supply frequency and the motor speed is as follows:

[0117] (5)

[0118] In formula (5), n is the motor speed, f is the power supply frequency, p is the number of pole pairs of the motor, and s is the slip rate of the AC asynchronous motor, where p and s are both constant and known;

[0119] The relationship between the power supply frequency of the AC asynchronous motor and the working pressure of the tail gun 3 is determined by actual measurement, namely:

[0120] f = y(P) (6)

[0121] In formula (6), f is the power supply frequency, P is the working pressure of the tail gun 3;

[0122] Combined with formula (2), the relationship between the power supply frequency of the AC asynchronous motor and the range of the tail gun 3 is obtained, namely:

[0123] f = j (R) (7)

[0124] Substitute the maximum and minimum values ​​of the tail gun 3 range obtained in step 2 into formula (7) to obtain the power supply frequency f corresponding to the maximum value of the tail gun 3 range: 1 , the power supply frequency f corresponding to the maximum value of the tail gun 3 range 2 , then the range of the AC asynchronous motor power supply frequency f is (f 1 , f 2 );

[0125] By default, as the horizontal sprinkler moves in the field, the AC asynchronous motor power supply frequency f changes linearly. When the horizontal sprinkler moves from the long side to the short side of the spraying plot, the AC asynchronous motor power supply frequency f changes with time as follows:

[0126] (8)

[0127] In formula (8), v is the travel speed of the translational sprinkler, D is the total distance moved by the translational sprinkler in the travel direction, and t is the travel time of the translational sprinkler;

[0128] When the translation sprinkler moves from the short side to the long side of the spraying plot, the change law of the AC asynchronous motor power supply frequency f over time is:

[0129] (9);

[0130] Step 4, obtaining the total water volume and average sprinkler intensity of the tail gun 3, and determining the nozzle diameter of the tail gun 3;

[0131] The specific process of step 4 is:

[0132] According to the variation law of the motor power supply frequency over time during mobile spraying and formula (6), the variation law of the working pressure of the tail gun 3 over time is obtained. Combined with formula (1), the variation law of the flow rate of the tail gun 3 over time is obtained, that is:

[0133] Q = w (t) (10)

[0134] Then the total water volume sprayed by the tail gun 3 is:

[0135] (11)

[0136] The average irrigation intensity in the spraying area of ​​the tail gun 3 is:

[0137] (12)

[0138] In formula (12), S 尾 The area that the tail gun 3 should spray;

[0139] The total water volume of the inner span low pressure refraction nozzle is:

[0140] (13)

[0141] In formula (13), i is the number of the low-pressure refractive nozzle, N is the total number of low-pressure refractive nozzles, and q i is the flow rate of the i-th low-pressure refraction nozzle;

[0142] The average irrigation intensity of the inner span low-pressure refraction sprinkler spray area is:

[0143] (14)

[0144] In formula (14), The area that the inner span low-pressure refraction nozzle should spray;

[0145] Compare and , judge the matching degree between the selected tail gun 3 flow rate and the inner span low pressure refraction nozzle flow rate, calculate the matching deviation coefficient δ, then:

[0146] = *100% (15)

[0147] When -10%< When <10%, it means that the flow rate of the tail gun 3 is highly matched with the flow rate of the inner span low-pressure refraction nozzle, and the process goes to step 5;

[0148] when <-10%, it means that the flow rate of the selected tail gun 3 is too small, and you need to select a nozzle with a larger diameter than the current one to replace the current nozzle, and repeat steps 1-4 until -10%< <10% and go to step 5;

[0149] when >10%, it means that the flow rate of the selected tail gun 3 is too large, and you need to select a nozzle with a smaller diameter than the current one to replace the current nozzle, and repeat steps 1-4 until -10%< <10% and go to step 5;

[0150] Step 5, optimizing the water distribution in the spraying area of ​​the tail gun 3;

[0151] The specific process of step 5 is:

[0152] The required spraying area of ​​the tail gun 3 is divided into m units with a spacing of 30m in the direction of travel of the translation sprinkler. Each unit is divided into trapezoids. For the jth unit, the time before and after the translation sprinkler passes through the unit is t j and t j+1 The lengths of the upper and lower bases of the trapezoid corresponding to this unit are R j and R j+1 , then the amount of water sprayed by the tail gun when the horizontal sprinkler passes through the unit for:

[0153] (16)

[0154] Total area sprayed by the unit for:

[0155] (17)

[0156] In formula (17), d is the spacing distance along the moving direction of the translation sprinkler irrigation unit;

[0157] Then the average sprinkler intensity of the tail gun in the jth unit is:

[0158] (18)

[0159] In order to make the water distribution in the tail gun 3 spraying area uniform, the average sprinkler intensity in different units should be consistent with the average sprinkler intensity of the entire spraying area, and the flow compensation coefficient in each unit should be calculated. :

[0160] ×100% (19)

[0161] The flow compensation in each unit is completed by adjusting the opening of the electric valve 7 on the water supply branch pipe 2. The relationship between the different working pressures of the tail gun 3 and the flow rate of the water supply branch pipe 2 and the relationship between the different openings of the electric valve 7 and the flow rate of the water supply branch pipe 2 are obtained by actual measurement. According to the relationship between the working pressure and the flow rate, and the relationship between different openings and the flow rate, the relationship between the flow compensation coefficient and the opening of the electric valve 7 is established, that is:

[0162] =s(Ψ)(20)

[0163] In formula (20), is the flow compensation coefficient, Ψ is the opening of the electric valve 7;

[0164] When the flow compensation coefficient ε is less than 0, the opening of the electric valve 7 is reduced, and when the flow compensation coefficient ε is greater than 0, the opening of the electric valve 7 is increased.

[0165] The method of the present invention ensures more reliably full-area spraying without leakage of non-rectangular plots and uniform distribution of water in the spraying area through the variable-range spraying of the spraying area boundary, matching of the inner-span low-pressure refractive nozzle and the tail gun sprinkler intensity, and precise adjustment of the flow rate in the tail gun spraying area.

[0166] Example 3

[0167] The variable spraying method of the tail gun of a translational sprinkler machine suitable for non-square fields of the present invention adopts the variable spraying device of the tail gun of the translational sprinkler machine suitable for non-square fields, and is specifically implemented according to the following steps:

[0168] Step 1, the tail gun 3 adopts a HY50 vertical rocker arm spray gun and matches an 18mm nozzle. The installation height of the tail gun 3 is 5m. The flow rate and range under different working pressures are measured as shown in Table 1;

[0169] Table 1 Flow rate and range at different working pressures

[0170]

[0171] It can be seen from Table 1 that the working pressure and flow rate of the tail gun 3 are related as follows:

[0172] Q=12.23ln(P)+38.4

[0173] The working pressure and range of the tail gun 3 are related by:

[0174] R=71.43P+10.89

[0175] Where, Q is the flow rate of the tail gun, m 3 / h; P is the working pressure of the tail gun, MPa; R is the range of the tail gun, m;

[0176] Step 2: Affected by the direction of the road, one side of the spraying plot is parallel to the road, and the plot is trapezoidal. Assume that the longer side of the two parallel sides of the spraying plot is B. 1 =100m, the shorter side is B 2 =80m. To achieve full-area spraying of the plot, a translational sprinkler unit with an inner span length of L and a tail gun range of R is used.

[0177] Obviously, the range of the tail gun during mobile spraying should be at the maximum value R 1 and the minimum value R 2 Variation between ranges;

[0178] According to Table 1, select R 2 is the range of the tail gun when the lower limit of the suitable working pressure is 0.2MPa, that is, 25m. At this time, the width of the inner span of the translational sprinkler irrigation unit is 55m. 1 45m;

[0179] When R 1 When the height is 45m, it can be known from R=71.43P+10.89 that the working pressure of the tail gun is 0.48MPa, that is, the working pressure range of the tail gun suitable for this plot is 0.2MPa~0.48MPa;

[0180] Step 3, for the AC booster pump 4, the AC asynchronous motor involved is a YE2-P variable frequency speed regulating motor, the number of motor pole pairs is 4, the slip rate is 0.1, and the relationship between the motor power supply frequency and the tail gun working pressure is measured to be:

[0181] f=109.63P;

[0182] The motor power supply frequency range corresponding to the tail gun working pressure of 0.2MPa-0.48MPa is 21.9Hz-53.3Hz;

[0183] The total length of the horizontal sprinkler unit in the direction of travel is 300m, and the travel speed is 60m / h. During the spraying process of the horizontal sprinkler unit, if Figure 3 As shown in the figure, moving from the short side to the long side of the plot, the change law of the motor power supply frequency over time is:

[0184] f=6.28t+21.9;

[0185] Moving from the long side to the short side of the plot, the change law of the motor power supply frequency over time is:

[0186] f=-6.28t+53.3;

[0187] Step 4, taking the spraying from the short side to the long side as an example, the change law of the working pressure of the tail gun over time is:

[0188] P=0.0573t+0.2;

[0189] The change law of tail gun flow rate over time is:

[0190] Q=12.23ln(0.0573t+0.2)+38.4;

[0191] At a speed of 60 m / h, the time required for a translational sprinkler unit to complete a spraying operation is 5 h, and the total water volume sprayed by the tail gun is 124.56 m 3 ;

[0192] The total area controlled by tail gun spraying is m 2 , then the average sprinkler intensity in the tail gun spraying area is 11.86mm;

[0193] The inner span length is 55m. 18 O3000 oscillating rotary low-pressure refraction nozzles are installed at intervals of 3m on the water supply pipeline. The flow rate of the O3000 nozzle is 2.1m 3 / h, the total amount of water sprayed within the inner span length of 55m during the spraying process is 189m 3 , spraying area is 16500m 2 , the average irrigation intensity of the inner span low-pressure refraction sprinkler spray area is 11.45mm;

[0194] Comparing the irrigation depth in the inner span and tail gun spraying control area, it can be seen that the deviation of the sprinkler irrigation intensity is only 3.57%. The currently selected tail gun model has a high matching degree with the low-pressure refraction nozzle model, and there is no need to adjust the tail gun nozzle size.

[0195] Step 5, such as Figure 4 As shown, the end spraying area of ​​the local block is divided into 10 units at intervals of 30m in the direction of the unit's travel. Each unit is divided into trapezoids. The spraying water volume, total spraying area and average sprinkler intensity in each unit are shown in Table 2. The sprinkler intensity in the unit is consistent with the average sprinkler intensity of the entire spraying area. The flow compensation coefficient in each unit is calculated as shown in Table 2;

[0196] Table 2

[0197]

[0198] like Figure 5As shown, for the adjustment of the valve opening, the electric valve in this embodiment uses an electric gate valve with linear flow characteristics. Therefore, in order to compensate for the flow fluctuation caused by the change of the working pressure of the spray gun and meet the same sprinkler irrigation intensity in the plots with different numbers in the tail gun spraying area, when the unit passes through the plots with different numbers, the opening of the electric valve on the tail gun water supply branch pipe needs to be adjusted by -7%~12.56%.

Claims

1. A variable spraying method of a translational sprinkler tail gun suitable for non-square fields, characterized in that: A variable spraying device for a tail gun of a translational sprinkler suitable for non-square fields is used, comprising a water supply main pipe (1), the water supply main pipe (1) being connected to one end of a water supply branch pipe (2), the other end of the water supply branch pipe (2) being connected to a tail gun (3), an electric valve (7) being arranged on one end of the water supply branch pipe (2) close to the water supply main pipe (1), an AC booster pump (4) being arranged on one end of the water supply branch pipe (2) close to the tail gun (3), the AC booster pump (4) being connected to a frequency converter (5), the frequency converter (5) being connected to a PLC controller (6), the PLC controller (6) and the electric valve (7) being connected to an interactive control terminal (8); Follow the steps below to implement it: Step 1, determining the relationship between the working pressure of the tail gun (3) and the flow rate and the range; Step 2, according to the shape of the spraying plot, taking the working pressure of the tail gun (3) not less than 0.2 MPa as a benchmark, obtaining the maximum and minimum values ​​of the range of the tail gun (3); The specific process of step 2 is: Assume that the spraying plot has two parallel sides of different lengths, the longer side is B1 and the shorter side is B2, and the span length of the inner span where the tail gun (3) is located is L; Then the maximum range R1 of the tail gun (3) is: R1=B1-L(3) Then the minimum range R2 of the tail gun (3) is: R2=B2-L(4) Substitute the maximum range R1 into formula (2) to obtain the working pressure P1 corresponding to the maximum range R1; substitute the minimum range R2 into formula (2) to obtain the working pressure P2 corresponding to the minimum range R2, P2>0.2MPa; If the working pressure P2 is less than 0.2 MPa, the span length of the inner span where the tail gun (3) is located is adjusted to L-ΔL, where the initial value of ΔL is 1m, with a step interval of 1m. At this time, the minimum range R2 ， =B2-L+ΔL, until the minimum range R2 ， Corresponding working pressure P2 ， is greater than 0.2Mpa, thereby obtaining the adjusted span length of the inner span where the tail gun (3) is located, and substituting it into formula (3) and formula (4), the maximum and minimum values ​​of the range of the tail gun (3) can be obtained; Step 3, establishing the relationship between the motor power supply frequency of the AC booster pump (4) and the range of the tail gun (3), and determining the change pattern of the motor power supply frequency over time during the mobile spraying process; Step 4, obtaining the total water volume and average irrigation intensity of the tail gun (3), and determining the nozzle diameter of the tail gun (3); Step 5, optimize the water distribution in the spraying area of ​​the tail gun (3).

2. The variable spraying method of the tail gun of a translational sprinkler suitable for non-square fields according to claim 1, characterized in that: The specific process of step 1 is as follows: according to the model and nozzle diameter of the tail gun (3), the flow rate of the tail gun (3) under different working pressures is determined from the product manual of the tail gun (3) or through actual measurement, and the working pressure and flow rate relationship of the tail gun (3) is fitted: Q = h (P) (1) In formula (1), Q is the flow rate of the tail gun (3), and P is the working pressure of the tail gun (3); According to the model of the tail gun (3), the nozzle diameter and the installation height of the tail gun (3) at the end of the translational sprinkler, the range of the tail gun (3) under different working pressures is determined by actual measurement, and the relationship between the working pressure and the range of the tail gun (3) is established: R = g(P) (2) In formula (2), R is the range of the tail gun (3), and P is the working pressure of the tail gun (3).

3. The variable spraying method of the tail gun of a translational sprinkler suitable for non-square fields according to claim 2, characterized in that: The specific process of step 3 is: For an AC booster pump (4), which includes an AC asynchronous motor, the relationship between the power supply frequency and the motor speed is as follows: （5） In formula (5), n is the motor speed, f is the power supply frequency, p is the number of pole pairs of the motor, and s is the slip rate of the AC asynchronous motor, where p and s are both constant and known; The relationship between the power supply frequency of the AC asynchronous motor and the working pressure of the tail gun (3) is determined by actual measurement, namely: f = y(P) (6) In formula (6), f is the power supply frequency, P is the working pressure of the tail gun (3); Combined with formula (2), the relationship between the AC asynchronous motor power supply frequency and the range of the tail gun (3) is obtained, namely: f = j (R) (7) Substitute the maximum and minimum values ​​of the tail gun (3) range obtained in step 2 into formula (7) to obtain the power supply frequency f1 corresponding to the maximum value of the tail gun (3) range and the power supply frequency f2 corresponding to the maximum value of the tail gun (3) range. Then, the variation range of the power supply frequency f of the AC asynchronous motor is (f1, f2). By default, as the horizontal sprinkler moves in the field, the AC asynchronous motor power supply frequency f changes linearly. When the horizontal sprinkler moves from the long side to the short side of the spraying plot, the AC asynchronous motor power supply frequency f changes with time as follows: （8） In formula (8), v is the travel speed of the translational sprinkler, D is the total distance moved by the translational sprinkler in the travel direction, and t is the travel time of the translational sprinkler; When the translation sprinkler moves from the short side to the long side of the spraying plot, the change law of the AC asynchronous motor power supply frequency f over time is: （9）。 4. The variable spraying method of the tail gun of a translational sprinkler suitable for non-square fields according to claim 3, characterized in that: The specific process of step 4 is: According to the variation law of the motor power supply frequency over time during mobile spraying and formula (6), the variation law of the working pressure of the tail gun (3) over time is obtained. Combined with formula (1), the variation law of the flow rate of the tail gun (3) over time is obtained, that is: Q = w (t) (10) Then the total amount of water sprayed by the tail gun (3) is: （11） The average irrigation intensity within the spraying area of ​​the tail gun (3) is: （12） In formula (12), S 尾 The area to be sprayed by the tail gun (3); The total water volume of the inner span low pressure refraction nozzle is: （13） In formula (13), i is the number of the low-pressure refractive nozzle, N is the total number of low-pressure refractive nozzles, and q i is the flow rate of the i-th low-pressure refraction nozzle; The average irrigation intensity of the inner span low-pressure refraction sprinkler spray area is: （14） In formula (14), The area that the low-pressure refraction nozzle should spray for the inner span; Compare and , judge the matching degree between the selected tail gun (3) flow rate and the inner span low pressure refraction nozzle flow rate, calculate the matching deviation coefficient δ, then: = *100%（15） When -10%< When <10%, it indicates that the flow rate of the tail gun (3) is highly matched with the flow rate of the inner span low-pressure refraction nozzle, and the process goes to step 5; when <-10%, it means that the flow rate of the selected tail gun (3) is too small, and you need to select a nozzle with a larger diameter than the current one to replace the current nozzle, and repeat steps 1-4 until -10%< <10% and go to step 5; when >10%, it means that the flow rate of the selected tail gun (3) is too large, and you need to select a nozzle with a smaller diameter than the current one to replace the current nozzle, and repeat steps 1-4 until -10%< If <10%, proceed to step 5.

5. The variable spraying method of the tail gun of a translational sprinkler suitable for non-square fields according to claim 4, characterized in that: The specific process of step 5 is: The required spraying area of ​​the tail gun (3) is divided into m units at intervals of 30 m in the direction of travel of the translational sprinkler. Each unit is divided into trapezoids. For the jth unit, the time before and after the translational sprinkler passes through the unit is t j and t j+1 The lengths of the upper and lower bases of the trapezoid corresponding to this unit are R j and R j+1 , then the amount of water sprayed by the tail gun when the horizontal sprinkler passes through the unit for: （16） Total area sprayed by the unit for: （17） In formula (17), d is the spacing distance along the moving direction of the translation sprinkler unit; Then the average sprinkler intensity of the tail gun in the jth unit is: （18） In order to make the water distribution in the tail gun (3) spraying area uniform, the average sprinkler intensity in different units should be consistent with the average sprinkler intensity of the entire spraying area, and the flow compensation coefficient in each unit should be calculated. : ×100%（19） The flow compensation in each unit is completed by adjusting the opening of the electric valve (7) on the water supply branch pipe (2). The relationship between different working pressures of the tail gun (3) and the flow rate of the water supply branch pipe (2) and the relationship between different openings of the electric valve (7) and the flow rate of the water supply branch pipe (2) are obtained through actual measurement. According to the relationship between the working pressure and the flow rate and the relationship between different openings and the flow rate, the relationship between the flow compensation coefficient and the opening of the electric valve (7) is established, that is: =s(Ψ)(20) In formula (20), is the flow compensation coefficient, Ψ is the opening of the electric valve (7); When the flow compensation coefficient ε is less than 0, the opening of the electric valve (7) is reduced, and when the flow compensation coefficient ε is greater than 0, the opening of the electric valve (7) is increased.

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