Development of surge irrigation control valve and self control

1 surge irrigation equipment composition

1.1 surge irrigation control valve

Considering the need of automatic irrigation in irrigated area, the surge control valve developed by the irrigation system uses bidirectional switch structure to switch the direction of water flow and control intermittently the water supply process according to the instructions of the self-control unit. Especially in the unattended state, irrigation can be quickly and automatically cut off the water flow after the end to avoid excessive irrigation caused by waste. The control valve is currently made of ferrous material, and its main components include: body, valve and deceleration. The valve body is similar in construction to a tee and consists of three sections of 200 mm (8 " Connected to the water source, the two ends of the outlet. Valve is a circular gate with a peripheral sealing gasket, wherein the upper and lower ends of the shaft through the water stop bearing and the valve body and gearbox connected by the gearbox control, gate around the center The axis of rotation at right angles, to achieve open and close the water flow state.Airtight gearboxes are fixed on both sides of the valve body and through the central axis and the gate phase.Cover is equipped with: (1) transmission mechanism, taking into account the worm has a stable work without Noise can be self-locking and other advantages, the design uses ordinary cylindrical worm drive and worm deceleration; (2) drive, used to control the valve opening and closing of the micro-DC motor; (3) locator, light control and light control panel , To determine the opening and closing of the valve state; (4) reducer, the high-speed motor (3000 r / min) speed down to 10 r / min or so by two stages of deceleration, and then drive the valve; , To prevent motor overload and guarantee Valve closed state.

1.2 automatic controller

The controller is the control center of the surge irrigation system. The control circuit board and the software are the core parts of the controller. It accepts manual input parameters and gives operation instructions to the surge valve to open and close the gate alternately. Gate position by the photocell positioning, the controller receives the photocell signal, the decision whether to open or close the motor. Self-control mainly consists of the following parts.

Master part. Using 89C518 microcontroller as the core, with a keyboard and display components. Keyboard used to set the system time, start time, each irrigation time, intermittent time and surge frequency. These input parameters are automatically saved, the power is off or power-down is not lost. Display consists of 6 LED digital tube display parameters and working time status, due to the use of a scanning mode to reduce power consumption. System clock is 24 h system, the use of battery backup, the clock is still working properly after shutdown.

Motor control section. Driven by 74LS07 4 sets of relays to promote the motor rotation around the two gates. Do not work at both ends of the motor ground. When the motor is rotating forward, the left end is connected to +6 V and the right end is grounded. When reversed, the left end is grounded and the right end is connected to +6 V.

Position sensing section. It consists of 4 groups of optocouplers, which respectively indicate the switch status of the two gates and sends the received signals back to the main control section.

Power section. It consists of a solar panel, a 4 Ah / 6 V battery, and an LM2940 reverse voltage regulator for low dropout power. Weekday solar battery float on the battery. When the surge irrigation system is running, the battery supplies power to the device and is supplied to the motherboard after being regulated by the LM2940. Taking into account the extraordinary situation, the power supply is also equipped with AC charging system.

Function selection part.With the "control" button to select surge valve operation mode, the controller can control the left valve, the right valve or the double valve respectively to realize the functions of full close, full open, single valve alternate operation.

The application of controller includes parameter setting and automatic operation. Controlled operation is to accept some basic input parameters, the control program operation, issued by the control center command is completed automatically. The operation procedure of parameter setting is as follows: (1) Turn on the power, the controller will reset the surge valve automatically. Left and right valves close at the same time. (2) Select "control mode" to determine the working status of surge valve. Right valve, double valve; (3) Select "System Time", use the "hour / minute / second" button to select the time object and use "+", "-" to adjust the system time; Use the "hour / minute / second" button to select the time object, use "+" and "-" to adjust the start time of the surge event. (5) Select the "irrigation time" Time object, use "+", "-" to determine the time of single-wave surge irrigation; (6) Select "Interval Time", select the time object with " "To determine the single surge irrigation stoppage time; (7) Select" surge ", with" + "," - "to adjust the number of surges, each press" + "in the second digital tube plus 1, To 99, each press "-" in the second digital tube minus 1, the minimum to 0.

After the above settings, the controller enters the automatic working state. It should be noted that the double valve control refers to the alternate working state of "left open right closed" or "right open left closed". When the "intermittent time" is greater than or equal to "irrigation time", at the end of one cycle, the two valves will simultaneously Off, closing time is "intermittent time" minus "irrigation time", and then enter the second cycle of working state; when the "intermittent time" is less than "irrigation time", the double valve can not work at the same time, in this case, Valve operation. Whenever you press the "System Reset" button, the surge valve around the valve will be closed at the same time, this irrigation ended.

1.3 control valve and self-control connection

For ease of use, to avoid illegal or misuse, the controller and the surge valve interface using industrial standards, the connection between the two can be used only plug the cable (the only plug), simple and safe operation.

2 equipment performance and characteristics

Developed surge irrigation equipment has the following working performance and features.

Under the dual-valve working condition, the maximum overcurrent Q of a single surge valve and the corresponding controllable irrigation area S are estimated by the following formula

Where A is the cross-sectional area of ​​the water pipe; d is the diameter of the water pipe; ε is the flow coefficient; h is the pressure head at the diversion mouth of the agricultural canal; λ is the head loss coefficient along the path; ξ is the local head loss coefficient; T is the irrigation cycle; m is the irrigation quota; t is the daily irrigation time; and η is the effective utilization factor of water. The schedule shows the maximum overcurrent Q of a single surge valve and the corresponding controllable irrigation area under the assumption that the crop rotation period is 7 days and the irrigation time is 12 hours per day. . For the canal irrigation area, when the water head differential at the diversion gate is 30 ~ 50 cm, the area controlled by the surge irrigation equipment is 4 ~ 6 hm2. In the well irrigation area, the control area depends on the surplus of the well pump Water head.

With the table single surge valve maximum overcurrent and the corresponding controllable irrigation area estimation

Head H / m Pipe length L / m

L = 25 m L = 50 m

ε Q / m3.s-1 S / hm2 ε Q / m3.s-1 S / hm2

0.3 0.4 0.030 5 4.61 0.324 4 0.024 7 3.74

0.5 0.4 0.039 4 5.95 0.324 4 0.031 9 4.83

Note: d = 0.2 m; λ = 0.026; Σξ = 2; m = 750 m3 / hm2; η = 0.75.

The operating voltage is 6 V, the average working current is 2.5 A, the switching time is T = 3 s, and the battery energy storage is 4 Ah / 6 V. In theory, the number of jobs is 1 920 times, the corresponding number of surges is 480 for double valves and 960 for single valves. By the equipment processing, installation accuracy is limited, the actual power consumption will reduce the number of battery after a charge. Nevertheless, a charge capacity is still able to meet the irrigation operation of the valve opening and closing energy consumption needs.

The size of the solar panel is 152 mm × 152 mm, the corresponding theoretical power is 1 VA, the average voltage is 8 V under normal lighting and the average charging current is 0.1 A. Battery fully discharged after the full time required for about 30 h, if the effective daily charge of 6 h calculation (10 am to 4 pm), you need 5 d. Therefore, it is recommended that the controller be placed in outdoor sunlight for one week to ensure safe operation before each use.

The structural design takes into account the versatility of a valve, both as a single-pipe system and as a double-pipe system for alternating commutation, increasing equipment flexibility. Due to the device's ability to automatically shut off the flow of water, unattended and remote control is achieved.

Controller parameters set simple, only involves the most basic parameters of surge irrigation, which will help farmers learn to grasp, easy to promote the application of the field.

The device is easy to operate. The user only needs to connect the self-control device and the surge valve with a cable, and the interface between the controller and the speed reducer is waterproof and dustproof, which is suitable for the climatic and environmental conditions of the field farmland.

3 preliminary assessment of the field

The developed surge irrigation equipment has carried out preliminary field tests in winter wheat irrigation experiments in well irrigation and drainage irrigation areas in 1998 respectively. Pouring valve inlet PE pipe and low pressure water pipe outlet or farm water diversion port connected, and the surge valve of the two outlets by a large number of gate field hose system connected. Gates on the hose can be directly discharged into the water for irrigation. The experimental design of the single-wide flow rate is 0.003 m3 / sm, the length of 150 ~ 200 m, the test results show that the whole set of equipment working in good condition, the surge valve to open and close the normal ease of flow switching time is accurate, the water gate effect Better, reached the original design requirements and performance indicators, with strong field practicality.

The assessment results also show that this set of equipment can be very conveniently applied in well irrigation area. On the one hand, the existing low-pressure pipe outlet can be conveniently connected with the surge valve inlet. On the other hand, the surplus pressure head of the well pump is The water supply by the PE hose provides enough power to ensure that the surge irrigation method requires a single wide flow rate.

The use of surge valve in a canal irrigation area is constrained by two factors. When the head is fixed, the water head loss along the water hose and the local head loss caused by the surge irrigation equipment will result in the decrease of the flow into the, and the inability to meet the surge Irrigation technical parameters of the request. According to the test results, the water head outlet pressure at the channel should be at least 30 cm, and the length of the surge valve water pipeline should not be too long. The second is that it is necessary to properly rebuild the structure of the outlet of the existing agricultural drainage so as to connect with the inlet of the surge valve.

4 Conclusion

The development of surge irrigation equipment suitable for the national conditions is one of the necessary conditions to realize the large-scale popularization and application of this water-saving irrigation method. Has developed a surge irrigation valve and automatic control valve with a multi-purpose, easy to operate features. Preliminary test results of field trials prove that this equipment has reached the design requirements and performance indicators, with strong field practicality. On this basis, we will further improve and perfect the quality and standards of control valves and self-controlled devices, replace the existing materials with light materials, reduce the weight of the equipment and make it easy to move flexibly in the field. In addition, field pipelines and corresponding pipe gates should be developed for surge irrigation equipment to provide a well-behaved, affordable surge surge irrigation system. There is reason to believe that, with the successful development and improvement of the surge irrigation equipment in our country and the series production of the surge irrigation system, the surge irrigation technology must be able to exert its due role in China's water-saving irrigation.

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