CN210890301U - Electric valve capable of realizing closed-loop control of corner - Google Patents

Abstract

An electric valve capable of realizing corner closed-loop control is used for flow regulation in the process industry. The valve consists of a direct current brushless motor, a cylindrical gear reducer, a worm and gear mechanism, a valve rod, a valve core, a valve body, a limit switch and a rotary encoder. The direct current brushless motor is adopted for driving, a motor rotor and a cylindrical gear shaft are coaxial, and a plurality of cylindrical gears form a reduction box; the tail end of the reduction gearbox is coaxial with the worm, and the worm is meshed with the worm wheel; the worm wheel is rigidly connected with the valve rod, and the valve rod is also rigidly connected with the valve core. Its advantage lies in, relates to case position closed loop control scheme, the trapezoidal acceleration and deceleration positioning algorithm of case and return stroke error compensation control strategy, compares in the domestic ZJKV type electric valve of equal bore, the utility model discloses electric control flap's positioning accuracy can be shown and is improved.

Description

Electric valve capable of realizing closed-loop control of corner

Technical Field

The utility model belongs to can realize corner closed-loop control's valve, in particular to novel electronic adjusting valve who improves on domestic ZJKV basis.

Background

The domestic ZJKV type electric valve is an important actuator responsible for flow regulation in the process industry, and the positioning precision of the electric valve plays a decisive role in maintaining the accuracy of fluid flow. The domestic electric valve is driven by a three-phase asynchronous motor, only has the positioning precision of 80-100 steps, and for the angular travel valve with the angle of 0-90 degrees, 100 steps mean that each operation step causes the valve core to rotate by 0.9 degrees, and the rotating angle of the valve core is completely determined by the electrifying time without driving torque control, and the actuator body is an open-loop control system and can hardly meet the requirement of high precision in the future development of the process industry. The relationship between the rotation angle and the time of the domestic valve is obtained through experimental tests, and the results are shown in the table 1:

TABLE 1 domestic ZJKV electric valve corner-time relation test data

As can be seen from table 1, when the energization time is less than 1s, the corner error rate is greater than 10%, and a relatively severe nonlinear relationship exists between the valve core corner and the time. In summary, the minimum operating angle of the domestic ZJKV type electric valve should not be less than 0.9 °, otherwise the valve core is easily positioned inaccurately. Compared with the prior art, the electric valves produced by foreign Metro and BTG companies have the precision of 15000-20000 steps, are only applied to special occasions with high precision requirements, are high in price and are not suitable for popularization and application, for example, the high-precision valve of DN125 is sold in a unit price of 18-20 ten thousand yuan, and is forbidden by many domestic enterprises. Therefore, the accuracy level of the domestic common electric valve is improved, and the electric valve has important significance.

Disclosure of Invention

The utility model discloses on domestic ZJKV electric valve's hardware basis, change asynchronous machine for DC brushless motor, configuration DC brushless motor drive plate, design DC brushless motor driven trapezoidal acceleration and deceleration positioning curve, build electric valve control platform, realize the stepless speed regulation of motor and the corner closed loop control of case to can be with the control unit embedding valve aircraft bonnet in, have the function that can realize the electromechanical control integration in the outward appearance.

The technical scheme of the utility model is that: the utility model provides a can realize corner closed-loop control's electrically operated valve, comprises parts such as direct current brushless motor, cylindrical gear, worm gear, valve rod, case, valve rod, motor drive circuit, controller, limit switch, rotary encoder, valve body, characterized by: an output shaft of the direct current brushless motor is sequentially connected with the cylindrical gear, the worm wheel and the valve rod so as to drive the valve core to rotate; the output shaft of the rotor is fixedly connected with the cylindrical gear, and the worm gear is fixedly connected with the valve rod; the output shaft side of the direct current brushless motor is provided with a Hall sensor, a position detection signal of the Hall sensor is transmitted to a controller, the output end of the controller is connected with a direct current brushless driving circuit, the speed regulation and the reversing of a rotor are realized through an electronic driving circuit, and the closed-loop control of the position of the rotor is realized; the rotary encoder is a spare part, and the encoder can not be installed when the valve is used.

Furthermore, the speed curve adopts a trapezoidal acceleration and deceleration positioning algorithm and comprises three processes of uniform acceleration, uniform speed and uniform deceleration, wherein when only the acceleration section and the deceleration section exist, the rotated angle of the valve core corresponds to the thinnest operating angle of the electric valve.

Further, the trapezoidal acceleration and deceleration positioning algorithm is realized based on an ATMega328P chip, and specifically, in an Arduino IDE programming environment, programming of the algorithm is performed in a c language. It should be noted that the programming aims to make the controller mechanically execute the rotation control of the dc brushless motor according to the rotation angle position signal inputted according to the requirement of the rotation angle closed-loop control, rather than relying on the improvement of the method of the present invention to realize the purpose of the closed-loop control.

Furthermore, the valve core starts to rotate at the maximum acceleration from rest, the valve core immediately enters the deceleration process at the same acceleration value after the acceleration process is finished, and when the deceleration of the valve core is zero, the rotating angle of the valve core is the finest operating angle.

Further, the maximum acceleration is obtained according to a torque equation and on the principle that a margin value of 65% is reserved.

Further, the finest operating angle corresponds to the highest execution precision of the valve, and the sum of the finest operating angle and the rotation angle of the valve core in the constant speed stage is equal to the target rotation angle.

Furthermore, the size of the target corner is a known quantity in each positioning process of the valve core, and the target corner has a strict corresponding relation with a trapezoidal acceleration and deceleration positioning curve.

Further, the flow regulation requirement strictly corresponds to the opening of the electric regulating valve, and the controller receives a flow regulation signal sent by the upper computer and calculates the flow regulation signal as a target rotation angle of the valve core according to the flow regulation requirement.

Furthermore, the rotary encoder and the valve rod are coaxially arranged, the rotor position signal obtained by the detection of the Hall sensor and the counting value of the rotary encoder about the position of the valve core are unified in dimension, and the mechanical clearance existing in the transmission system is obtained.

Further, when the valve core rotates reversely, the valve core is influenced by the mechanical clearance, a process that only the rotor of the direct current brushless motor rotates but the valve core does not rotate exists, and the rotation angle corresponding to the mechanical clearance is added to the original target rotation angle by adopting an error compensation strategy to obtain the correct target rotation angle.

Further, in the action process of opening or closing the valve, the valve core runs according to a trapezoidal acceleration and deceleration positioning curve strictly.

The utility model has the advantages that:

for the domestic ZJKV type electric valve, on the premise of not increasing much cost, the asynchronous motor is replaced by a direct current brushless motor. According to the mechanical characteristics of the direct current brushless motor, the output torque and the rotating speed are in a linear proportional relation, and the linear relation between the rotating angle of the valve core and the time can be ensured. In addition, in the parameter configuration of the motor drive plate, a selection function item for stepless regulation of the rotor speed is provided, so that the speed can be ensured to be stable and adjustable in the action process of the valve core, and a three-section trapezoidal speed preset algorithm is provided for the positioning process of the valve, so that the positioning precision of the electric valve is effectively improved. The utility model discloses the unique advantage that has in appearance does: the control unit is small in size, and in the actual use process, the control panel can be placed in a hood of the electric valve, so that the electromechanical control integration is realized in appearance.

Drawings

Fig. 1 is a schematic view of the structure of the electric valve of the present invention;

fig. 2 is a schematic view of the internal principle of the electric valve of the present invention;

fig. 3 is a schematic view of a closed-loop control system of the electric valve of the present invention;

fig. 4 is a block diagram of a speed closed-loop control circuit of the electric valve of the present invention;

fig. 5 is a schematic view of a return error clearance of the electric valve of the present invention;

the main element symbols are as follows: 1. a hood; 2. a motor groove; 3. a DC brushless motor; 4. a cylindrical gear reduction box; 5. a worm; 6. a worm gear; 7. a limit switch; 8. a photoelectric encoder; 9. a valve body; 10. a valve stem; 11. valve core

Detailed Description

In order to describe the present invention more clearly, the electric valve for realizing the closed-loop control of the rotation angle will be further described in detail with reference to the attached drawings.

An electric valve capable of realizing corner closed-loop control is composed of a direct-current brushless motor, a cylindrical gear, a worm gear, a valve rod, a valve core, a valve rod, a motor driving circuit, a controller, a limit switch, a rotary encoder and a valve body. An output shaft of the direct current brushless motor is sequentially connected with the cylindrical gear, the worm wheel and the valve rod so as to drive the valve core to be opened or closed; the output shaft of the rotor is fixedly connected with the cylindrical gear, and the worm gear is fixedly connected with the valve rod; the rotary encoder is a spare part, and the encoder can not be installed when the valve is used; the Hall sensor is arranged in the output shaft side of the direct current brushless motor, a position detection signal is transmitted to the controller, a speed curve of the electric adjusting valve is realized in the controller, and the output end of the controller is connected with the direct current brushless motor driving plate.

The angular displacement of the valve core after uniform acceleration, uniform speed and uniform deceleration is the target corner.

The controller receives a flow regulation signal sent by the DCS, and the controller performs accounting according to the flow regulation requirement to obtain a target corner.

The rotary encoder is coaxially installed with the valve rod, and after a rotor position signal obtained by detection of the Hall sensor and a count value of the rotary encoder about the position of the valve core are unified in dimension, a mechanical clearance value existing in a transmission system is obtained; when the valve core rotates reversely, an error compensation strategy is adopted, and the rotating angle corresponding to the mechanical clearance is added with the original target rotating angle to obtain the correct target rotating angle.

The concrete description is as follows:

fig. 1 shows the utility model discloses electric valve's structure is constituteed, adopts direct current brushless motor as the driving source to the cylinder gear box realizes the switching-over function through worm gear mechanism as the reduction gear, specifically is: the rotor output shaft of the direct current brushless motor is connected with a cylindrical gear reducer, the center of the tail end of the cylindrical gear is rigidly and fixedly connected with a worm to form a shaft, a motor rotating shaft transmits power to a valve rod after being subjected to cylindrical gear reduction and worm and gear torque increase, and finally the valve rod drives a valve core to complete rotation. The limit switch is not marked in fig. 1, and when the valve rod is collided with the position appointed by the limit switch in the forward rotation or the reverse rotation, the situation that the valve core rotates to the full-open or full-closed limit position at the moment is shown, the electric valve can automatically cut off the power, and the protection function of the valve core is realized.

With reference to the valve structure shown in fig. 1, fig. 2 illustrates the basic principle of the inside of the electric valve of the present invention, the corner characteristic of the dc brushless motor has a dominant influence on the positioning performance of the valve element, and controls the output current, the corner information, the start/stop state of the dc brushless motor through LY-F2, and further realizes the control of the valve element corner condition of the electric valve.

Fig. 3 shows the structure composition of the closed-loop control system of the electric valve of the present invention, in terms of hardware design, the development board with model number of LY-F2 is used as the main controller, the development board has 14 digital I/O pins and 6 analog input pins, the control chip with model number of ATMega328P is used, and the clock frequency of the chip can reach 16 MHZ. The model of the direct current brushless motor driver is AQMD3605BLS, a rotor speed closed-loop control mode is supported, and a photoelectric isolation converter with the model of U-485G is configured, so that RS485 communication is realized to learn detailed parameters of the motor. In the aspect of a power supply system, a module partition power supply mode is adopted, the LY-F2 development board is provided with 7-9V input voltage by an independent power supply or a computer, and the motor driver is provided with 24V input voltage by a switching power supply. In the aspect of program design, based on a computer with a processor of Intel (R) core (TM) i5-4200CPU @1.60Hz 2.30GHz, IDE programming software with a compatible version is downloaded, a USB-to-serial port driver CH341 is installed, data communication is carried out through a port COM3, the program is burnt and written to a single chip microcomputer and is permanently stored, after the controller is powered on, the controller directly enters a program execution state, if the program needs to be changed, the program needs to be communicated through the port again, and the updated program is downloaded to the single chip microcomputer. The valve control system has the function of monitoring the opening and closing states of the electric valve in real time.

When the rotor of the brushless DC motor reaches the specified rotating speed in the acceleration process, the uniform speed motion process is not carried out, the speed reduction stage is directly entered, the angular displacement generated by the valve core when the rotating speed is reduced to zero is called as the finest operating angle of the valve, the smaller the finest operating angle is, the higher the subdivision degree of the rotation angle of the electric valve is, the finer the action of the valve core is, and the method for determining the finest operating angle is to increase the acceleration value and reduce the time consumption in the acceleration and deceleration processes.

The direct current brushless motor has a stepless speed regulation function, which means that in a trapezoidal speed curve, the maximum value of the speed can be set through a driver, the acceleration cannot exceed the allowable acceleration value under the normal application condition of the direct current brushless motor, and when the acceleration keeps the allowable value, the time consumed by the rotor in the acceleration and deceleration processes is the shortest, namely the angular displacement rotated by the valve core is the finest operating angle of the electric valve.

Fig. 4 is the utility model discloses electric valve's speed closed loop control circuit block diagram, dc brushless motor works under the speed regulation mode, control circuit takes rotational speed-current cascade negative feedback to adjust, and winding current control circuit is as the inner ring, and rotational speed control circuit is as the outer loop to regard case position signal as the output, switch on through the order of PWM regulation power tube, change stator winding's current value, adjust driving torque, and then reach the speed governing purpose, maintain on the speed setting value with the rotational speed of phase case at arbitrary moment. The speed setting is the specific time allocation result of the trapezoidal speed curve, and is not described herein again.

Figure 5 illustrates the transmission system clearance of the electric valve of the present invention. Mechanical clearances inevitably exist between the driving motor and the transmission member, between the transmission members, and between the transmission members and the shutoff valve core during power transmission, and are particularly common during gear meshing. When the actuator rotates forwards, the positioning precision of the valve core is not affected by the transmission mechanical clearance, and the forward error caused by the mechanical clearance is completely eliminated after two or more times of effective forward rotations; when the actuator is rotated in the reverse direction, the encoder detects a slower position than the actual position. The mechanical error is generated at the moment of reverse rotation, namely only the driving gear rotates, and the driven gear is in a neutral state. The existence of the return error can certainly cause the positioning accuracy of the electric valve to be reduced, and an error compensation strategy is needed to eliminate the influence. The utility model discloses the tactics as follows: if the current valve opening state is consistent with the last time, the compensation of the mechanical transmission clearance of the valve is not needed; if the current opening direction of the valve is opposite to the last time, mechanical transmission clearance compensation is needed, and the method specifically comprises the following steps: the rotation time of the valve core is prolonged, and the compensation angle corresponding to the part is equal to the mechanical clearance value between the gears.

Right the utility model relates to a can realize corner closed-loop control's electric valve's location characteristic and study, obtain the test data of table 2.

Table 2 the utility model discloses electric valve's experimental test data

According to table 2, it maintains below 12% basically to find positioning error, compares with table 1, and the error rate has obvious reduction, explains and is in the utility model discloses have better positioning characteristic, can effectively promote domestic ordinary electric valve's positioning accuracy.

Claims (4)

1. An electric valve capable of realizing corner closed-loop control comprises a valve rod, a valve core and a controller, and is characterized by further comprising a direct current brushless motor and a motor driver; a Hall element is arranged in the DC brushless motor and is used for detecting the corner position of an inner rotor of the DC brushless motor; the motor driver comprises a PWM controller, a current detection device and a current regulation device; the current detection device, the current regulation device and the PWM controller form an inner loop current control loop; the Hall element, the controller, the motor driver and the direct current brushless motor are sequentially connected to form an outer ring corner control loop;

the output shaft of the direct current brushless motor, the cylindrical gear reduction box, the worm and worm gear commutator and the valve rod are sequentially connected, and the valve core is installed on the valve rod, so that the valve core rotates along with the direct current brushless motor when the direct current brushless motor rotates.

2. The electric valve capable of realizing closed-loop control of the rotating angle according to claim 1, characterized in that the controller adopts a DCS system, a main controller of the DCS system adopts a LY-F2 development board, and an ATMega328P singlechip is installed on the development board; the output end of the main controller is connected with the input end of the motor driver, and the output end of the motor driver is connected with the direct current brushless motor; the motor driver model is AQMD3605 BLS; the model of the DC brushless motor is 42BL50S03-230TR 9.

3. The electrically operated valve capable of realizing closed-loop control of the rotation angle according to claim 1, further comprising a rotary encoder, wherein the rotary encoder is electrically connected with an input end of the controller; when the DC brushless motor works, the rotary encoder detects the angular displacement of the valve core.

4. An electrically operated valve capable of realizing closed-loop control of rotation angle according to claim 1, wherein the reduction ratio between the rotor shaft and the valve rod of the dc brushless motor is 1500: 1.

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