Method for determining valve switching state by motor current and motor valve

Abstract

This invention provides a method and a motor valve for determining the opening and closing state of a valve using motor current. By collecting and analyzing the real-time changes in current during valve operation, the actual direction of valve movement can be determined. During valve opening, under the action of spring force, the output current of the permanent magnet DC motor experiences a slow increase before reaching its peak value, which lasts for a certain period. During valve closing, due to the absence of spring resistance, the current only rapidly increases to its maximum value when the valve is fully closed and the motor valve stalls. Therefore, there is a significant difference in the current curves during valve opening and closing. By collecting and analyzing the real-time changes in current, the actual direction of valve movement can be determined. This invention's method can accurately identify both the opening and closing directions of the valve, is simple in structure, reduces costs, is stable and reliable, and has a longer service life.

Description

Technical Field

[0001] This invention relates to the field of metering instrument technology, and in particular to a method for determining the valve opening / closing status using motor current and a motor valve. Background Technology

[0002] With the widespread adoption of intelligent and IoT-based metering instruments such as smart water meters, smart gas meters, and heat meters, valves, as core actuators for on / off control, flow regulation, safety shutdown, and remote management, directly determine the operational safety, control accuracy, and service life of these instruments through their reliability and monitorability. In scenarios such as prepaid management, abnormal shutdown, overdue payment flow restriction, and remote maintenance, it is not only necessary to drive valves to perform opening or closing actions, but also to accurately determine the actual direction of valve movement in real time to avoid valve opening / closing failures caused by inconsistencies between commands and actual actions.

[0003] Currently, the valve status detection methods commonly used in the industry are mechanical limit switches and micro switches, which rely on contact to achieve detection. The drawbacks are: mechanical wear, susceptibility to vibration, and short lifespan. Especially in flammable, explosive, or corrosive gas environments such as gas meters, the contacts are easily corroded, oxidized, and stuck by the gas, leading to signal failure, false triggering, or failure. The reliability and long-term stability are difficult to meet the requirements of meter operation.

[0004] Meanwhile, existing detection solutions can only achieve unidirectional detection and cannot identify the entire direction. They have serious limitations in judgment and are structurally complex: most structures can only determine the movement of the valve in one direction, either "fully open" or "fully closed," and cannot identify both directions of movement at the same time; even if some solutions can detect the position, they cannot distinguish whether the valve core is moving in the opening or closing direction during the valve movement. Once the motor reverses, the transmission slips, or the valve core gets stuck, the control system cannot identify the abnormal direction in time, which can easily cause control failure.

[0005] In summary, existing methods for determining the direction of valve movement suffer from several problems, including unreliable mechanical structures, susceptibility to corrosion, inability to determine only a single direction, lack of full-range direction recognition, poor stability, high cost, and complex structures. These limitations make it difficult to simultaneously meet the application requirements of metering instruments for high reliability, long lifespan, corrosion resistance, miniaturization, and low cost. Therefore, developing a non-contact, corrosion-resistant method capable of simultaneously determining a single direction of opening or closing, with a simple structure and high reliability, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a method and a motor valve for determining the valve's on / off state using motor current. This method enables the determination of the motor valve's movement direction throughout its entire operation, thereby ensuring consistency between the actual movement direction of the motor valve and the valve state recorded by the motor valve control panel.

[0007] This invention provides a method for determining the opening and closing status of a valve using motor current, applicable to motor-driven valves, the method comprising: When the motor valve receives a valve operation command sent by the external main control system, it controls the permanent magnet DC motor to work and at the same time starts the internal timer to start counting. If the timing event of the internal timer reaches the preset time, the current detection function is activated to continuously detect the real-time current value of the permanent magnet DC motor during the operation of the motor valve. Record the first time point when the real-time current value exceeds the first current threshold and the second time point when it exceeds the second current threshold; The valve opening / closing status is determined based on the difference between the first and second time points.

[0008] Optionally, the motor valve includes a motor valve housing, a motor valve seal, a pull rod assembly, a permanent magnet DC motor, a motor valve control board, and a spring, wherein the spring provides resistance only during the valve opening process.

[0009] Optionally, the first current threshold corresponds to the current value when the motor begins to overcome the spring resistance, and the second current threshold corresponds to the current value when the motor stalls or is about to stall.

[0010] Optionally, determining the valve switching state based on the difference between the first time point and the second time point includes: If the difference between the first time point and the second time point is greater than the preset time difference threshold, it is determined to be a valve opening process; If the difference between the first time point and the second time point is less than a preset time difference threshold, it is determined to be a valve closing process.

[0011] Optionally, the preset time difference threshold is set according to the shortest time it takes for the current of the motor valve to rise from the first current threshold to the second current threshold during the valve opening process. The preset time difference threshold is greater than the longest time required for the current to jump from the first current threshold to the second current threshold during the valve closing process, and less than the shortest time required for the current to rise from the first current threshold to the second current threshold during the valve opening process.

[0012] The present invention also provides a motor valve, the motor valve comprising a motor valve housing and a permanent magnet DC motor disposed within the motor valve housing; A motor valve control board is fixedly installed below the permanent magnet DC motor. The motor valve control board is connected to an external main control system via wires and is used to execute the method described above for determining the valve opening and closing status using motor current.

[0013] Optionally, the motor shaft of the permanent magnet DC motor is connected to the tie rod assembly via threads, a motor valve seal is connected to the top of the tie rod assembly, and a spring is sleeved on the outside of the tie rod assembly.

[0014] Optionally, the motor valve control board is connected to the permanent magnet DC motor via a wire.

[0015] The method for determining the valve opening / closing state using motor current provided by this invention can distinguish between the two directions of valve movement—opening and closing—simply by collecting and analyzing the current changes of the motor driving the valve, resulting in a simpler structure. It also eliminates the need for physical detection components such as limit switches and Hall elements, along with their assembly processes, significantly reducing material and manufacturing costs. Furthermore, it avoids common sensor failures such as mechanical contact wear or magnetic interference, leading to a longer system lifespan, making it particularly suitable for long-term maintenance-free intelligent instrument environments. In addition, the judgment logic, based on digital thresholds and time difference comparisons, is simple, efficient, and offers good real-time performance.

[0016] The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a cross-sectional view of the motor valve according to an embodiment of the present invention; Figure 2 This is a system block diagram of the motor valve control board according to an embodiment of the present invention; Figure 3 This is a flowchart of an embodiment of the present invention; Figure 4 This is a current curve diagram of the valve opening process according to an embodiment of the present invention; Figure 5 This is a current curve diagram of the valve closing process according to an embodiment of the present invention. Detailed Implementation

[0018] The embodiments of the present invention are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the present invention and are not restrictive.

[0019] This invention provides a method for determining the valve's open / closed state using motor current, applied to a motor-driven valve. The motor-driven valve includes a valve housing 1, a valve seal 2, a lever assembly 3, a permanent magnet DC motor 4, a valve control board 5, and a spring 6. In this embodiment, the method for determining the valve's open / closed state using motor current is embedded in the valve control board 5. The system block diagram of the valve control board 5 is shown below. Figure 2 As shown, the motor valve control board is connected to a power source and has an internal timer for timing. It also has motor valve driving function and current acquisition function.

[0020] like Figure 1 As shown, the motor valve includes a motor valve housing 1 and a permanent magnet DC motor 4 housed within the motor valve housing 1. The motor shaft of the permanent magnet DC motor 4 is connected to a pull rod assembly 3 via a thread. A motor valve seal 2 is connected to the top of the pull rod assembly 3, and a spring 6 is fitted around the outside of the pull rod assembly 3. The motor valve control board 5 is mounted and fixed below the permanent magnet DC motor 4, and the two are connected by a wire. The motor valve control board 5 is connected to an external main control system (such as the main control board of an external gas meter or water meter) via a wire. The permanent magnet DC motor has a rated voltage of 3V and a no-load current of 50mA. The motor valve control board can use an STM32 series MCU with a built-in 12-bit ADC current sampling.

[0021] The method for determining the valve opening / closing status using motor current in this embodiment includes the following steps S1 to S4.

[0022] S1: When the motor valve receives a valve operation command from the external main control system, it controls the permanent magnet DC motor to work and simultaneously starts the internal timer. In this embodiment, the timer can be integrated into the motor valve control board 5. Specifically, when the main control board of the external gas meter or water meter issues a valve operation command to the motor valve control board 5, the motor valve control board 5 drives the permanent magnet DC motor 4 to move, thereby causing the pull rod assembly 3 to move downwards. The pull rod assembly 3 then causes the motor valve seal 2 to move downwards, thus opening the valve. Simultaneously, the motor valve control board 5 starts the internal timer.

[0023] S2; If the timing event of the internal timer reaches the preset time, the current detection function is activated to continuously detect the real-time current value of the permanent magnet DC motor during the operation of the motor valve.

[0024] When the internal timer of the motor valve control board 5 reaches the preset time T0 for the current detection of the motor valve, the current detection function inside the motor valve control board 5 is activated to continuously detect the current of the permanent magnet DC motor 4 during the operation of the motor valve. In practical applications, the preset time T0 can be set according to different valve characteristics, preferably within the range of 0-400ms.

[0025] S3: Record the first time point when the real-time current value exceeds the first current threshold and the second time point when it exceeds the second current threshold; S4: Determine the valve opening / closing status based on the difference between the first time point and the second time point.

[0026] In this embodiment, the first current threshold corresponds to the current value when the motor begins to overcome the spring resistance, and the second current threshold corresponds to the current value when the motor stalls or is about to stall.

[0027] When the motor valve seal 2 descends to the original length of the spring 6 that is externally fastened to the tie rod assembly 3, the motor valve seal 2 begins to compress the spring 6 to do work under the action of the spring 6, which increases the load on the permanent magnet DC motor 4. Therefore, the output current of the permanent magnet DC motor 4 increases significantly and continuously, which increases the current value I detected by the motor valve control board 5. When this current value I is greater than the first current threshold I1 preset inside the motor valve control board 5, this moment is recorded as the first time point T1.

[0028] When spring 6 is compressed to its limit position, the motor valve reaches the fully open state and stalls, causing the output current of the permanent magnet DC motor 4 to increase significantly to its maximum value again. This causes the current value I detected by the motor valve control board 5 to increase again. When this current value I exceeds the second current threshold I2 preset inside the motor valve control board 5, this moment is recorded as the second time point T2.

[0029] If the difference between the first time point T1 and the second time point T2 is greater than the preset time difference threshold ΔT, it is determined to be a valve opening process; if the difference between the first time point T1 and the second time point T2 is less than the preset time difference threshold ΔT, it is determined to be a valve closing process. In other words, the motor valve control board 5 compares the difference between T2 and T1 with the internally preset time ΔT. When T2-T1 is greater than ΔT, the motor valve control board 5 determines that this valve action is a valve opening process and simultaneously synchronizes this record to the main control board of the external gas meter or water meter to achieve state unification. Here, I1 is preferably 50mA, I2 is preferably 150mA, T0 is preferably 80ms, and ΔT is preferably 200ms.

[0030] In an optional embodiment of the present invention, the preset time difference threshold is set according to the shortest time required for the current of the motor valve to rise from the first current threshold to the second current threshold during the valve opening process; the preset time difference threshold is greater than the longest time required for the current to jump from the first current threshold to the second current threshold during the valve closing process, and less than the shortest time required for the current to rise from the first current threshold to the second current threshold during the valve opening process.

[0031] The actual valve closing process is as follows: When the motor valve performs the valve closing action, spring 6 is naturally released, and the output current of the permanent magnet DC motor 4 remains stable. Only when the motor valve seal 2 reaches the maximum closing position, i.e., the motor valve reaches the fully closed state, does the motor valve stall, causing the output current of the permanent magnet DC motor 4 to suddenly and significantly increase to its maximum value. Since there is no spring action, the value of T2-T1 is definitely less than the preset time ΔT inside the motor valve control board 5. The motor valve control board 5 determines that this valve action is a valve closing process and simultaneously synchronizes this record to the main control board of the external gas meter or water meter, thereby achieving state unification and ending the program operation.

[0032] Figure 3 This is an optional embodiment of the method for determining the valve opening / closing state using motor current, such as... Figure 3 As shown, the specific steps of the method for determining the valve opening / closing state using motor current in this optional embodiment are as follows: Step 1: Power on the motor valve control board.

[0033] Step 2: System parameter initialization.

[0034] Step 3: The motor valve control board determines whether it has received the valve switching command from the main control board. If yes, it jumps to step 4; otherwise, it continues to execute the step of determining whether it has received the valve switching command from the main control board.

[0035] Step 4: The motor valve control board determines whether the valve switching command has been successfully parsed. If yes, proceed to step 5; otherwise, proceed to step 3.

[0036] Step 5: Drive the motor valve to operate.

[0037] Step 6: Start the timer.

[0038] Step 7: Determine whether the maximum valve action time Tmax set by the system has been reached. If yes, proceed to step 18; otherwise, proceed to step 8.

[0039] Step 8: Determine whether the valve opening current detection time T0 has been reached. If yes, proceed to step 9; otherwise, proceed to step 8.

[0040] Step 9: Activate valve current detection.

[0041] Step 10: Compare whether the measured current is greater than I1. If it is, proceed to step 11; otherwise, proceed to step 10.

[0042] Step 11: Record the current time as T1.

[0043] Step 12: Compare whether the measured current is greater than I2. If yes, proceed to step 13; otherwise, continue with step 12.

[0044] Step 13: Record the time as T2.

[0045] Step 14: Compare whether T2-T1 is greater than the set time ΔT. If yes, proceed to step 15; otherwise, proceed to step 16.

[0046] Step 15: Determine that the valve action is opening.

[0047] Step 16: Determine that the valve action is to close the valve.

[0048] Step 17: Continuously supply power to ensure the valve operates fully and record the parameters.

[0049] Step 18: De-energize the valve.

[0050] Figure 4 This is a current curve diagram of the valve opening process according to an embodiment of the present invention; Figure 5 This is a current curve diagram of the valve closing process according to an embodiment of the present invention.

[0051] In an optional embodiment, the following parameters are preset in the storage area of ​​the motor valve control board: I1=120mA (representing the initial current threshold when encountering spring resistance), I2=250mA (representing the high current threshold when approaching or starting stall), T0=30ms (avoiding the surge current at the moment of motor start-up, and detecting it after the operation is stable), ΔT=50ms (the time difference threshold used to distinguish between opening and closing the valve).

[0052] Valve opening process: When the external main control board issues the "open valve" command, the control board drives the motor to rotate forward and simultaneously starts the timer. When the timer reaches 30ms, the current is sampled every 1ms. As the lever compresses the spring, the current gradually increases from no-load. When the current first exceeds 120mA, T1 = 31ms is recorded; when the current continues to rise and exceeds 250mA, T2 = 95ms is recorded. Calculating T2 - T1 = 64ms, which is greater than 50ms, indicates that the valve has opened.

[0053] Valve closing process: When the external main control board issues a "valve close" command, the control board drives the motor to reverse. Since there is no need to overcome spring force, the current remains at a low level (approximately 60-80mA) until the seal touches the valve port, at which point the motor enters a stall state. At this time, the current jumps from 80mA to 260mA in a very short time (e.g., 3ms). Record T1=32ms, T2=35ms, T2-T1=3ms, which is less than 50ms, indicating a valve closing action.

[0054] Using the above methods, the control board can accurately identify the valve's movement direction without any mechanical sensors, and can determine whether the valve is in position based on the stroke time.

[0055] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for determining the valve opening / closing state using motor current, characterized in that, Applied to motor valves, the method includes: When the motor valve receives a valve operation command sent by the external main control system, it controls the permanent magnet DC motor to work and at the same time starts the internal timer to start counting. If the timing event of the internal timer reaches the preset time, the current detection function is activated to continuously detect the real-time current value of the permanent magnet DC motor during the operation of the motor valve. Record the first time point when the real-time current value exceeds the first current threshold and the second time point when it exceeds the second current threshold; The valve opening / closing status is determined based on the difference between the first and second time points.

2. The method according to claim 1, characterized in that, The motor valve includes a motor valve housing, a motor valve seal, a pull rod assembly, a permanent magnet DC motor, a motor valve control board, and a spring, wherein the spring provides resistance only during the valve opening process.

3. The method according to claim 2, characterized in that, The first current threshold corresponds to the current value when the motor begins to overcome the spring resistance, and the second current threshold corresponds to the current value when the motor stalls or is about to stall.

4. The method according to claim 1, characterized in that, Determining the valve switching status based on the difference between the first and second time points includes: If the difference between the first time point and the second time point is greater than the preset time difference threshold, it is determined to be a valve opening process; If the difference between the first time point and the second time point is less than a preset time difference threshold, it is determined to be a valve closing process.

5. The method according to claim 4, characterized in that, The preset time difference threshold is set according to the shortest time it takes for the current of the motor valve to rise from the first current threshold to the second current threshold during the valve opening process. The preset time difference threshold is greater than the longest time required for the current to jump from the first current threshold to the second current threshold during the valve closing process, and less than the shortest time required for the current to rise from the first current threshold to the second current threshold during the valve opening process.

6. An electric motor valve, characterized in that, The motor valve includes a motor valve housing and a permanent magnet DC motor disposed within the motor valve housing; A motor valve control board is fixedly installed below the permanent magnet DC motor. The motor valve control board is connected to an external main control system via wires and is used to execute the method of determining the valve opening and closing status by using motor current as described in any one of claims 1 to 5.

7. The motor valve according to claim 6, characterized in that, The motor shaft of the permanent magnet DC motor is connected to the tie rod assembly via threads. The top of the tie rod assembly is connected to a motor valve seal, and a spring is sleeved on the outside of the tie rod assembly.

8. The motor valve according to claim 6, characterized in that, The motor valve control board is connected to the permanent magnet DC motor via wires.

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