A high-precision straight stroke electric actuator with double position locating function and a position detecting method thereof

Abstract

The application discloses a high-precision straight stroke electric actuator with double-position positioning and relates to the technical field of electric actuators. A Hall sensor assembly is arranged corresponding to the rotor magnet steel of a driving motor; an output gear is fixedly arranged on a center rod and rotates synchronously; a first encoding gear is engaged with the output gear; a second encoding gear is engaged with the first encoding gear and has a tooth number difference with the first encoding gear; two magnetic angle sensors respectively sense the rotation angles of corresponding magnets, and the absolute rotation position of the center rod is calculated in combination with the tooth number difference. The application constructs a double-position positioning system, guarantees the dynamic response speed of the motor, eliminates the position error caused by the gap and wear of the speed reduction mechanism, improves the control precision and stability of the actuator, realizes the position information keeping without power supply or light source in the power-off state, and directly reads the current absolute position without recalibration after secondary power-on.

Description

Technical Field

[0001] This invention relates to the field of electric actuator technology, and in particular to a high-precision dual-position positioning linear electric actuator and its position detection method. Background Technology

[0002] Linear electric actuators are widely used in industrial automation process control to drive precise linear displacement of components such as valves and dampers. One of their core performance indicators is the accuracy and reliability of output position (i.e., valve position) detection. In applications in industries such as petrochemicals, power, water treatment, pharmaceuticals, and nuclear power, the position detection accuracy and reliability of the actuator directly affect the stability and production safety of the entire control system. Especially in applications with extremely high position control requirements, such as emergency shut-off valves, boiler feedwater regulating valves, precision batching valves, and safety-grade valves, the actuator not only needs to achieve high-precision position feedback under normal power conditions, but also must be able to accurately record and restore the current actual position after unexpected power failure, battery depletion, or manual operation. Otherwise, it may lead to loss of process parameter control, production interruption, or even safety accidents.

[0003] Currently, the position detection technologies for existing linear electric actuators are mainly divided into two categories: one is the position detection method based on photoelectric sensors, and the other is the position feedback method based on potentiometers.

[0004] Position detection based on photoelectric sensors records the number of actuator rotations and angles using photoelectric encoders, thereby calculating the valve's stroke position. However, this method has a fatal flaw: photoelectric sensors rely on power and a light source. When the actuator unexpectedly loses power and the backup battery is depleted, the photoelectric sensor will cease operation and cannot record the position information at the moment of power failure. More seriously, if the actuator's transmission chain between the motor and the load is disengaged due to manual operation, even if the photoelectric sensor can still record the motor's position, it cannot simultaneously determine the actual displacement at the load end. Upon power-up, the system's position information will be completely lost, requiring recalibration of the stroke. This not only increases operational complexity but can also cause irreparable damage in emergencies.

[0005] Position feedback based on potentiometers typically employs a multi-gear reduction mechanism to transmit the actuator's output motion to the potentiometer, using changes in the potentiometer's resistance to reflect position information. This method has several significant drawbacks: First, mechanical wear is inevitable during the transmission of multiple gears. With increasing usage time, gear backlash gradually increases, leading to a continuous decline in position feedback accuracy and a shortened lifespan. Second, potentiometers themselves suffer from issues such as varying contact resistance and poor linearity, further limiting the improvement of overall detection accuracy. Finally, the complex transmission structure of multiple gears also increases the actuator's size and failure rate.

[0006] Therefore, regardless of whether it's a traditional potentiometer solution or a photoelectric sensor-based position detection method, the position detection system faces a more fundamental dilemma when the actuator experiences an abnormal power outage or when the handwheel is manually operated for testing or maintenance. For example, in situations such as partial stroke testing of emergency shut-off valves, nuclear power plant overhauls, and unattended stations on long-distance pipelines, equipment may be shut down for extended periods, during which the valve is manually turned. Upon power restoration, if the system lacks true absolute position memory capability after power failure, it will lose the current true valve position, necessitating expensive full-range mechanical calibration or zero-return operations. This is completely unacceptable in many critical processes where reset actions are not permitted.

[0007] Furthermore, most existing linear electric actuators commonly employ a design that integrates the motor, drive control board, display module, feedback module, input / output module, and other electronic components into a single cavity. This design presents two serious problems: First, the magnets and stator coils inside the drive motor generate a strong alternating magnetic field around the motor when energized. This magnetic field can cause electromagnetic interference to nearby electronic components, and may even magnetize some sensitive components, leading to problems such as distorted control signals and inaccurate position detection. Second, the motor generates a large amount of heat during prolonged operation. This heat is difficult to dissipate within the sealed cavity, causing the operating temperature of electronic components to rise, accelerating component aging, reducing the overall performance and stability of the actuator, and in severe cases, even causing the actuator to malfunction or become uncontrollable. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art by providing a high-precision dual-position positioning linear electric actuator and its position detection method.

[0009] The technical solution of this invention: A high-precision dual-position positioning linear electric actuator, comprising a housing, a central rod, a drive motor, a reduction transmission mechanism, a magnetic encoder assembly, and a Hall sensor assembly; the central rod is rotatably mounted inside the housing, and its rotational motion is converted into linear displacement output; the Hall sensor assembly is configured corresponding to the rotor magnet of the drive motor, and is used to detect the rotational position of the drive motor when energized; the magnetic encoder assembly includes an output gear, a first encoding gear, a second encoding gear, a first magnet, a second magnet, a first magnetic angle sensor, and a second magnetic angle sensor; the output gear is fixedly sleeved on the central rod and rotates synchronously with the central rod; the first encoding gear meshes with the output gear. The first and second coding gears mesh with each other, and there is a difference in the number of teeth between them. The first magnet is fixed on the first coding gear and rotates synchronously with it, and the second magnet is fixed on the second coding gear and rotates synchronously with it. The first and second magnetic angle sensors are fixedly installed inside the housing and are respectively installed above the first and second magnets and arranged at intervals. The first and second magnetic angle sensors are used to sense the rotation angle of the corresponding magnets. By combining the angle information sensed by the first and second magnetic angle sensors with the difference in the number of teeth between the first and second coding gears, the absolute rotation position of the center rod is calculated.

[0010] By adopting the above technical solution, a dual-position positioning system was constructed, consisting of Hall sensor detection at the motor end and magnetic encoder output detection. This system achieves two-stage closed-loop position control, ensuring the dynamic response speed of the motor while eliminating position errors caused by clearance and wear in the reduction mechanism, thus improving the overall control accuracy and stability of the actuator. On one hand, an absolute position detection scheme using dual-encoder gear tooth difference combined with two magnetic angle sensors is employed. The absolute rotational position of the center rod is calculated based on the tooth difference, enabling the system to maintain position information without any power source or light source in the event of power failure. Upon power-up, the current absolute position can be directly read without recalibrating the stroke, solving the problem of traditional photoelectric encoders failing to record position after power loss. On the other hand, the Hall sensor assembly is positioned corresponding to the rotor magnet of the drive motor, detecting the motor's rotational position when powered on. This forms a dual-position detection architecture with the magnetic encoder assembly, allowing the two position detection systems to cross-check each other, improving system reliability and position detection accuracy. Furthermore, the magnetic encoder assembly is directly connected to the center rod, using only one set of output gears for reduction. Compared to the traditional multi-stage gear reduction potentiometer scheme, this reduces mechanical transmission links, lowers accumulated mechanical clearance and wear, and improves position feedback accuracy and service life.

[0011] In one possible design, the drive motor is externally mounted outside the housing, away from the magnetic encoder assembly.

[0012] By adopting the above design, the drive motor is spatially isolated from the magnetic encoder assembly and other electronic components. This avoids electromagnetic interference to the magnetic encoder assembly caused by the strong electromagnetic field generated when the magnets and stator coils inside the motor are energized, prevents the magnetic angle sensor from experiencing a decrease in angle detection accuracy due to external stray magnetic fields, and avoids the failure of electronic components due to long-term magnetization. At the same time, the independent external placement of the motor facilitates heat dissipation, preventing the heat generated by the motor operation from accumulating in the sealed cavity and causing the operating temperature of the electronic components to rise. This improves the overall stability and service life of the actuator, and also facilitates later maintenance and replacement, allowing motor maintenance to be completed without disassembling the electronic cavity.

[0013] In one possible design, the first coding gear has one less tooth than the second coding gear.

[0014] The design described above, with one less tooth, creates a periodic angular difference between the two encoder gears as they rotate multiple times with the central rod. This angular difference has a one-to-one mapping relationship with the number of rotations, ensuring that the angle combination of the two encoder gears is unique within the maximum detection range. This allows for accurate calculation of the cumulative number of rotations and precise angles of the central rod, providing a reliable physical basis for subsequent calculation of the number of rotations using angle values ​​sensed by two magnetic angle sensors. This achieves multi-turn absolute position detection using the vernier caliper principle, simplifying the calculation algorithm while ensuring detection accuracy and reducing the computational requirements of the controller.

[0015] In one possible design, the first and second coding gears are made of plastic, each with a mounting groove at its center top, and the first and second magnets are respectively fixedly installed in their corresponding mounting grooves.

[0016] With the above design, the encoding gear is made of plastic, which is lighter and has a smaller moment of inertia than metal gears, which helps to reduce interference with the magnetic field of the magnet; the embedded installation method makes the magnet and gear firmly connected, which can withstand high-speed rotation and vibration impact, thus improving the reliability of the magnetic encoder.

[0017] In one possible design, both the first and second magnetic angle sensors are angle position sensor chips based on the differential horizontal Hall magnetic induction principle, used to sense absolute angles within the range of 0° to 360°, and output angle data through a digital interface.

[0018] With the above design, this chip has excellent anti-stray magnetic field interference capability, which can effectively suppress the influence of external magnetic fields on the detection results and further improve the stability of position detection; it directly outputs absolute angle data in the range of 0° to 360°, without the need to find a reference zero point after power-on, and can obtain the current angle value upon power-on, providing a technical basis for realizing the power-off memory function.

[0019] In one possible design, the drive motor is connected to the central rod via a reduction gear transmission mechanism. The reduction gear transmission mechanism includes a worm and a worm wheel. The worm wheel sleeve is mounted on the central rod and can rotate relative to the central rod. The worm's shaft meshes with the worm wheel, and the worm's axis is perpendicular to the axis of the central rod and parallel to the output shaft axis of the drive motor. One end of the worm is connected to the output shaft of the drive motor via a single-stage reduction gear, and the other end of the worm is connected to a handwheel mechanism.

[0020] The above design employs a worm gear reducer mechanism, which has advantages such as large transmission ratio, compact structure, smooth operation, and low noise. It also has a self-locking characteristic, which can automatically lock the actuator position when the motor stops rotating to prevent the load from reversing. One end of the worm gear is connected to the motor through a single-stage reduction gear, which can match the motor speed and improve the output torque. The other end is connected to a handwheel mechanism, which facilitates manual operation in emergency situations and improves the safety of the system.

[0021] In one possible design, the reduction gear mechanism also includes a sun gear, several planetary gears, a ring gear, a planetary shaft, and a planetary constellation; the sun gear is integrally connected to the turbine and located below the turbine, and the sun gear meshes with each planetary gear; the ring gear is fixed inside the housing and meshes with each planetary gear; the planetary shaft is mounted at the center of each planetary gear and passes through the planetary constellation, driving the planetary constellation to rotate; the planetary constellation is connected to the central key.

[0022] By adopting the above design, a planetary gear reduction is added to the worm gear reduction, achieving a larger reduction ratio and multi-stage power transmission. This allows the drive motor to drive the central rod to rotate with a smaller torque, while improving transmission efficiency and smoothness. The integrated connection between the sun gear and the worm gear reduces transmission links and connection gaps, improving transmission accuracy and power transmission synchronization. The planetary reduction mechanism has advantages such as high load-bearing capacity, uniform torque distribution, and smooth operation. It can withstand large impact loads and extend the service life of the actuator.

[0023] In one possible design, the bottom and top sections of the central rod are respectively a lead screw section and a smooth section. The smooth section passes through the upper cavity, middle cavity, and lower cavity of the housing, while the lead screw section is located in the lower cavity of the housing. A needle roller bearing is sleeved on the smooth section of the central rod. A plane bearing is installed on the upper and lower sides of the needle roller bearing. The upper plane bearing is installed in the upper cavity of the housing, and the lower plane bearing is installed in the lower cavity of the housing. The needle roller bearing is installed in the middle cavity of the housing.

[0024] With the above design, the smooth section is supported by a combination of needle roller bearings and upper and lower planar bearings. The needle roller bearings bear the radial load, ensuring the radial stability of the center rod during rotation, while the upper and lower planar bearings bear the axial load, limiting the axial movement of the center rod. This achieves high coaxiality and axial positioning accuracy of the center rod's rotational motion. The high coaxiality ensures the meshing accuracy between the output gear and the first encoding gear, reduces gear wear and transmission errors, and thus improves the position detection accuracy of the magnetic encoder.

[0025] In one possible design, the lead screw segment is connected to a nut, which in turn is connected to a hollow output assembly to output linear displacement.

[0026] The above design converts the rotational motion of the central rod into linear displacement output through the cooperation of the lead screw section and the nut. The hollow output assembly provides a standardized linear output interface, which is convenient for connection with actuators such as valves.

[0027] Another technical solution of the present invention: a position detection method for a high-precision dual-position positioning linear electric actuator, characterized by comprising the following steps: S1: In the powered-on operating state, the drive motor drives the central rod to rotate through the reduction transmission mechanism; the Hall sensor assembly detects the position of the magnet of the drive motor rotor in real time to achieve the first position detection; S2: The center rod drives the output gear to rotate synchronously, the output gear drives the first encoding gear and the first encoding gear drives the second encoding gear; the first magnetic angle sensor detects the rotation angle of the first magnet and the second magnetic angle sensor detects the rotation angle of the second magnet. S3: Based on the angle values ​​detected by the first magnetic angle sensor and the second magnetic angle sensor, and combined with the difference in the number of teeth between the first and second coding gears, calculate the number of rotations of the first or second coding gear, and calculate the absolute rotation position of the center rod from the number of rotations and the rotation angle of the corresponding coding gear, thereby realizing the second position detection; S4: In the power-off state, the magnetic coupling relationship between the first magnet and the first magnetic angle sensor, and between the second magnet and the second magnetic angle sensor remains unchanged, and the magnetic encoder assembly can maintain the current position information without power. If the actuator is rotated by the handwheel mechanism during the power-off period, the two encoding gears drive the corresponding magnets to rotate synchronously, and the magnetic coupling relationship is updated synchronously. S5: After the second power-on, directly read the current angle values ​​of the first magnetic angle sensor and the second magnetic angle sensor. The current absolute position of the actuator can be obtained through the calculation method in step S3, without the need to recalibrate the stroke.

[0028] Using the above technical solution, under power-on conditions, the Hall sensor assembly detects the position of the magnets on the rotor of the drive motor in real time (first position detection), and the magnetic encoder assembly detects the absolute rotational position of the center rod through the output gear, the encoding gear, and the magnetic angle sensor (second position detection). The two sets of position detection can verify each other and work together to improve the dynamic control accuracy and system reliability. Under power-off conditions, since the first and second magnets are permanent magnets, their magnetic field direction is objectively maintained with the physical position of the magnets. The magnetic coupling relationship can be maintained without any power supply. If the actuator is operated through the handwheel mechanism during this period, the magnetic coupling relationship is updated synchronously. Therefore, the position information is always synchronized with the mechanical position. Attached Figure Description

[0029] Figure 1 This is a cross-sectional view of the overall structure of the present invention; Figure 2 This is a cross-sectional view of the magnetic encoder assembly of the present invention; Figure 3 This is a cross-sectional view of the drive motor of the present invention; Figure 4 For the present invention Figure 1 A magnified view of a portion of the document; Figure 5 This is a flowchart of the detection method of the present invention; Among them, 1. shell; 11. upper cavity; 12. middle cavity; 13. lower cavity; 2. Center rod; 21. Lead screw section; 22. Smooth section; 3. Drive motor; 31. Rotor magnet; 4. Hall sensor assembly; 5. Reduction gear transmission mechanism; 51. Worm gear; 52. Turbine gear; 53. First stage reduction gear; 54. Handwheel mechanism; 55. Sun gear; 56. Planetary gear; 57. Ring gear; 58. Planetary shaft; 59. Planetary constellation; 6. Magnetic encoder assembly; 61. Output gear; 62. First encoding gear; 63. Second encoding gear; 64. First magnet; 65. Second magnet; 66. First magnetic angle sensor; 67. Second magnetic angle sensor; 7. Needle roller bearings; 8. Surface bearing; 9. Nuts; 10. Hollow-out output assembly. Detailed Implementation

[0030] like Figures 1 to 5The high-precision dual-position positioning linear electric actuator shown includes a housing 1, a central rod 2, a drive motor 3, a reduction gear transmission mechanism 5, a magnetic encoder assembly 6, and a Hall sensor assembly 4. The housing 1 has multiple mutually separated cavities that house the central rod 2, the reduction gear transmission mechanism 5, and the magnetic encoder assembly 6, while also providing protection and support. The central rod 2 is rotatably inserted into the housing 1, and its rotational motion is converted into linear displacement output, making it the core component for the actuator's power output. The drive motor 3 provides the power source for the actuator, transmitting power to the central rod 2 through the reduction gear transmission mechanism 5. The magnetic encoder assembly 6 detects the absolute rotational position of the central rod 2, and the Hall sensor assembly 4 detects the rotational position of the drive motor 3. Together, they constitute a dual-position positioning system, achieving high-precision and high-reliability position control.

[0031] The housing 1 has an external mounting position for the drive motor 3. The drive motor 3 is externally mounted on the housing 1, away from the magnetic encoder assembly 6 and other electronic components inside the housing 1, effectively isolating it from the electronic components inside the housing 1 in space. This mounting method effectively isolates the magnetic field and heat generated by the drive motor 3 during operation, preventing the motor's magnetic field from interfering with the detection accuracy of the magnetic encoder. It also prevents the heat generated by the motor from accumulating in the electronic cavity, reducing the operating temperature of the electronic components and improving the long-term operational stability of the system.

[0032] The central rod 2 is divided into two sections along its axial direction: a lead screw section 21 near the bottom and a smooth section 22 near the top. The inner cavity of the housing 1 is divided into an upper cavity 11, a middle cavity 12, and a lower cavity 13 corresponding to the different sections of the central rod 2. The smooth section 22 extends from the upper cavity 11 of the housing 1 through the middle cavity 12 into the lower cavity 13, while the lead screw section 21 is located within the lower cavity 13 of the housing 1. A needle roller bearing 7 is sleeved on the smooth section 22 and installed in the middle cavity 12 of the housing 1 to bear radial loads and ensure the radial stability of the central rod 2 during rotation. Plane bearings 8 are respectively installed on the upper and lower sides of the needle roller bearing 7. The upper plane bearing 8 is installed in the upper cavity 11 of the housing 1, and the lower plane bearing 8 is installed in the lower cavity 13 of the housing 1. The upper and lower plane bearings 8 bear axial loads and limit the axial movement of the central rod 2. The three-point support structure of needle roller bearing 7 and upper and lower plane bearings 8 ensures high coaxiality and axial positioning accuracy of the rotational movement of the center rod 2, thereby guaranteeing transmission accuracy and position detection accuracy.

[0033] The lead screw section 21 is connected to the nut component 9, and the nut component 9 is connected to the hollow output assembly 10. When the center rod 2 rotates, the lead screw section 21 drives the nut component 9 to move axially, thereby converting the rotational motion of the center rod 2 into linear displacement output. The hollow output assembly 10 provides a standardized linear output interface for connecting actuators such as valve stems.

[0034] The drive motor 3 is connected to the central rod 2 via a reduction transmission mechanism 5. The reduction transmission mechanism 5 includes a worm 51, a worm gear 52, and a planetary gear system 56. The worm gear 52 is sleeved on the central rod 2, and a bearing is provided between the worm gear 52 and the central rod 2, allowing them to rotate relative to each other. The worm 51's shaft meshes with the worm gear 52, and the axis of the worm 51 is perpendicular to the axis of the central rod 2. One end of the worm 51 is connected to the output shaft of the drive motor 3 via a first-stage reduction gear 53 to achieve first-stage reduction. The other end of the worm 51 is connected to a handwheel mechanism 54. In the power-off or debugging state, the operator can manually rotate the worm 51 via the handwheel mechanism 54, thereby driving the worm gear 52 and the central rod 2 to rotate, achieving manual operation.

[0035] The planetary gear system 56 is located below the turbine 52 and includes a sun gear 55, several planetary gears 56, a ring gear 57, a planetary shaft 58, and a planetary constellation 59. The sun gear 55 is integrally connected to the turbine 52, located below the turbine 52, and rotates synchronously with the turbine 52. The ring gear 57 is fixed inside the housing 1. The sun gear 55 meshes with each of the planetary gears 56, and each of the planetary gears 56 simultaneously meshes with the ring gear 57. The planetary shaft 58 is mounted at the center of each of the planetary gears 56 and passes through the planetary constellation 59. When the sun gear 55 rotates, it drives each of the planetary gears 56 to revolve within the ring gear 57, and drives the planetary constellation 59 to rotate via the planetary shaft 58. The planetary constellation 59 is connected to the central rod 2 via a key, thereby transmitting power to the central rod 2 and driving the central rod 2 to rotate. The planetary gear system 56 achieves further speed reduction and torque increase based on the worm gear 51 reduction. At the same time, multiple planetary gears 56 share the load, reducing the force on individual gears and improving transmission smoothness and service life.

[0036] When the drive motor 3 is powered on, the motor output shaft drives the worm gear 51 to rotate via the first-stage reduction gear 53. The worm gear 51 drives the worm wheel 52 to rotate, which in turn drives the sun gear 55, which is integrally connected to it, to rotate. The sun gear 55 drives the planetary constellation 59 to rotate via the planetary gear 56, and the planetary constellation 59 ultimately drives the center rod 2 to rotate synchronously via a key connection. When manual operation is required, turning the handwheel mechanism 54 will drive the worm gear 51 to rotate, which in turn drives the center rod 2 to rotate via the aforementioned transmission chain.

[0037] The magnetic encoder assembly 6 is housed within the housing 1 and includes an output gear 61, a first encoding gear 62, a second encoding gear 63, a first magnet 64, a second magnet 65, a first magnetic angle sensor 66, and a second magnetic angle sensor 67. The output gear 61 is fixedly sleeved on the top of the smooth section 22 of the central rod 2 and rotates synchronously with the central rod 2. Both the first encoding gear 62 and the second encoding gear 63 are rotatably mounted within the housing 1. The first encoding gear 62 meshes with the output gear 61, and the second encoding gear 63 meshes with the first encoding gear 62. There is a difference in the number of teeth between the first encoding gear 62 and the second encoding gear 63. In this embodiment, the first encoding gear 62 has one less tooth than the second encoding gear 63; specifically, the tooth ratio can be set to 47:48, meaning the first encoding gear 62 has 47 teeth and the second encoding gear 63 has 48 teeth.

[0038] Both the first encoding gear 62 and the second encoding gear 63 are made of plastic, are lightweight, have low rotational inertia, and good self-lubrication. Each of the first encoding gear 62 and the second encoding gear 63 has a mounting groove at its center tip. The first magnet 64 is fixedly installed in the mounting groove of the first encoding gear 62, and the second magnet 65 is fixedly installed in the mounting groove of the second encoding gear 63. The first magnet 64 rotates synchronously with the first encoding gear 62, and the second magnet 65 rotates synchronously with the second encoding gear 63.

[0039] The first magnetic angle sensor 66 and the second magnetic angle sensor 67 are both fixedly mounted on the circuit board inside the housing 1, and are respectively mounted directly above the first magnet 64 and the second magnet 65 and arranged at intervals, with a spacing of 1 to 3 mm between them.

[0040] The first magnetic angle sensor 66 is used to sense the rotation angle of the first magnet 64, and the second magnetic angle sensor 67 is used to sense the rotation angle of the second magnet 65. In this embodiment, both the first magnetic angle sensor 66 and the second magnetic angle sensor 67 adopt angle position sensor chips based on the differential horizontal Hall magnetic induction principle. They integrate two pairs of differential Hall Wheatstone bridges placed at 90 degrees to each other, which can effectively cancel common-mode interference from external stray magnetic fields, output absolute angle data within the range of 0 to 360 degrees, and communicate with the microcontroller through digital interfaces such as IIC or SSI. Due to the use of the differential horizontal Hall magnetic induction principle, the sensor itself has good anti-interference capability. Combined with the external structure design of the drive motor 3, the impact of electromagnetic interference on the position detection accuracy is further reduced.

[0041] Hall sensor assembly 4 is mounted on drive motor 3, corresponding to the rotor magnet 31 of drive motor 3. In this embodiment, drive motor 3 is a permanent magnet brushless motor, with permanent magnets embedded inside its rotor. Hall sensor assembly 4 is used to detect the position of the magnets on the rotor of drive motor 3 in real time when powered on, outputting the absolute angle signal of the rotor to provide position feedback to the motor controller, thereby realizing high-precision closed-loop position control and commutation control of the motor. In the powered-on operation state, Hall sensor assembly 4 detects the rotational position of the motor rotor to achieve the first position detection; magnetic encoder assembly 6 detects the absolute rotational position of the center rod 2 to achieve the second position detection. The two position detection systems are independent of each other and can be mutually verified, improving the reliability and safety of the system.

[0042] The working principle and testing method of the high-precision dual-position positioning linear electric actuator of the present invention are as follows: In the powered-on operating state, the drive motor 3 drives the central rod 2 to rotate through the reduction transmission mechanism 5. The rotational motion of the central rod 2 is converted into the linear motion of the hollow output assembly 10 through the cooperation of the lead screw section 21 and the nut 9. During this process, the Hall sensor assembly 4 detects the position of the magnet of the rotor of the drive motor 3 in real time, realizing the first position detection and providing position feedback for the vector control of the motor. At the same time, the central rod 2 drives the output gear 61 to rotate synchronously, the output gear 61 drives the first encoding gear 62 to rotate, and the first encoding gear 62 drives the second encoding gear 63 to rotate at different speeds. The first magnetic angle sensor 66 detects the rotation angle of the first magnet 64, and the second magnetic angle sensor 67 detects the rotation angle of the second magnet 65.

[0043] Based on the angle values ​​detected by the two magnetic angle sensors, and combined with the tooth difference between the first coded gear 62 and the second coded gear 63, the controller calculates the absolute rotational position and corresponding linear stroke of the center rod 2 through the following steps: Let the number of teeth on the output gear be Z0, the number of teeth on the first encoded gear be Z1=47, and the number of teeth on the second encoded gear be Z2=48, with a difference of 1 between them. The lead screw is P.

[0044] The first magnetic angle sensor senses the rotation angle of the first magnet in real time and outputs a first angle value α (0°≤α<360°); the second magnetic angle sensor senses the rotation angle of the second magnet in real time and outputs a second angle value β (0°≤β<360°).

[0045] Because the first and second coding gears have a one-tooth difference in the number of teeth, their relative angle accumulates linearly with the number of rotations as they rotate with the central rod, forming a unique angle combination. The cumulative number of rotations N of the first coding gear is determined by the relationship between α and β, and the value of N ranges from 0 to Z1-1. The formula for calculating the cumulative number of rotations N is: N = round ((Z2×β - Z1×α) / 360°) The `round()` function is used for rounding to the nearest integer. Theoretically, the value of (Z2×β - Z1×α) should be an integer multiple of 360°. In practical applications, small deviations caused by sensor errors can be eliminated by rounding.

[0046] The formula for calculating the absolute rotation angle θ of the central rod is: θ = (N × 360° + α) × (Z1 / Z0) Where N×360°+α is the total rotation angle of the first encoding gear, Z1 / Z0 is the transmission ratio between the first encoding gear and the output gear, the output gear rotates synchronously with the central rod, so θ is the absolute rotation angle of the central rod.

[0047] The formula for calculating the absolute linear travel L of the hollow output assembly is: L = θ × P / 360° Calculation Example Assuming in this embodiment, the number of teeth of the output gear Z0 = 20, the lead screw P = 5mm, and at a certain moment, the first magnetic angle sensor detects an angle α = 180°, and the second magnetic angle sensor detects an angle β = 187.66°, then: Total number of rotations: N = round ((48×187.66°-47×180°) / 360°) = round ((9007.68° -8460°) / 360°) = round (547.68° / 360°) = round (1.521) = 2 Absolute rotation angle of the center rod: θ = (2 × 360° + 180°) × (47 / 20) = 900° × 2.35 = 2115° Absolute linear travel: L = 2115° × 5mm / 360° = 29.375mm Through the above calculations, the controller can obtain the current precise absolute position of the actuator, thus achieving the second position detection.

[0048] Since the first magnet 64 and the second magnet 65 are permanent magnets, their magnetic field direction is determined by their physical position and does not rely on any external power source. In the power-off state, regardless of where the central rod 2 is manually rotated, the magnetic field direction of the magnets will change synchronously and remain constant. After power-on, the microcontroller directly reads the α and β values ​​and calculates the current absolute position through the above steps, without relying on any historical position data or power-maintained memory, and without performing any travel calibration or zero-return operation.

[0049] In the event of a power outage, the magnetic encoder assembly 6 can maintain its current position information without a power source. If, during a power outage, the operator rotates the actuator via the handwheel mechanism 54, the handwheel drives the worm gear 51 to rotate, which in turn drives the turbine gear 52. The turbine gear 52, through the planetary gear system 56 and the planetary constellation 59, drives the central rod 2 to rotate. The central rod 2 then drives the output gear 61 to rotate synchronously, which in turn drives the first encoding gear 62, which in turn drives the second encoding gear 63. The first magnet 64 rotates synchronously with the first encoding gear 62, and the second magnet 65 rotates synchronously with the second encoding gear 63. Therefore, the magnetic coupling between the first magnet 64 and the first magnetic angle sensor 66, and between the second magnet 65 and the second magnetic angle sensor 67, is updated synchronously, ensuring that the position information remains synchronized with the mechanical position.

[0050] After the second power-on, the system directly reads the first angle value α output by the first magnetic angle sensor 66 and the second angle value β output by the second magnetic angle sensor 67, calculates the absolute rotational position of the center rod 2 according to the above steps one to three, and then calculates the current linear displacement position based on the screw pitch. The current valve position can be obtained directly without recalibrating the stroke.

Claims

1. A high-precision dual-position positioning linear electric actuator, characterized in that, It includes a housing (1), a center rod (2), a drive motor (3), a speed reduction transmission mechanism (5), a magnetic encoder assembly (6), and a Hall sensor assembly (4). The central rod (2) is rotatably inserted into the housing (1), and its rotational motion is used to convert it into linear displacement output; The Hall sensor assembly (4) is set corresponding to the rotor magnet (31) of the drive motor (3) and is used to detect the rotation position of the drive motor (3) when it is powered on. The magnetic encoder assembly (6) includes an output gear (61), a first encoding gear (62), a second encoding gear (63), a first magnet (64), a second magnet (65), a first magnetic angle sensor (66), and a second magnetic angle sensor (67); the output gear (61) is fixedly sleeved on the central rod (2) and rotates synchronously with the central rod (2); the first encoding gear (62) meshes with the output gear (61), the second encoding gear (63) meshes with the first encoding gear (62), and there is a difference in the number of teeth between the first encoding gear (62) and the second encoding gear (63); The first magnet (64) is fixed on the first encoding gear (62) and rotates synchronously with it; the second magnet (65) is fixed on the second encoding gear (63) and rotates synchronously with it. The first magnetic angle sensor (66) and the second magnetic angle sensor (67) are fixedly disposed inside the housing (1) and are respectively installed above the first magnet (64) and the second magnet (65) and arranged at intervals. The first magnetic angle sensor (66) and the second magnetic angle sensor (67) are respectively used to sense the rotation angle of the corresponding magnet. The absolute rotational position of the center rod (2) is calculated by combining the angle information sensed by the first magnetic angle sensor (66) and the second magnetic angle sensor (67) with the difference in the number of teeth between the first coded gear (62) and the second coded gear (63).

2. The high-precision dual-position positioning linear electric actuator according to claim 1, characterized in that: The drive motor (3) is externally mounted outside the housing (1) and away from the magnetic encoder assembly (6).

3. The high-precision dual-position positioning linear electric actuator according to claim 1, characterized in that: The first coding gear (62) has one less tooth than the second coding gear (63).

4. The high-precision dual-position positioning linear electric actuator according to claim 1, characterized in that: The first encoding gear (62) and the second encoding gear (63) are plastic parts, and each of them has a mounting groove at its center top. The first magnet (64) and the second magnet (65) are respectively fixedly installed in the corresponding mounting groove.

5. The high-precision dual-position positioning linear electric actuator according to claim 1, characterized in that: The first magnetic angle sensor (66) and the second magnetic angle sensor (67) are both angle position sensor chips based on the differential horizontal Hall magnetic induction principle, used to sense absolute angles in the range of 0° to 360°.

6. The high-precision dual-position positioning linear electric actuator according to claim 1, characterized in that: The drive motor (3) is connected to the center rod (2) via the reduction transmission mechanism (5); the reduction transmission mechanism (5) includes a worm (51) and a turbine (52), the turbine (52) is sleeved on the center rod (2) and can rotate relative to the center rod (2); the worm (51) meshes with the turbine (52), the axis of the worm (51) is perpendicular to the axis of the center rod (2) and parallel to the output shaft axis of the drive motor (3); one end of the worm (51) is connected to the output shaft of the drive motor (3) via a first-stage reduction gear (53), and the other end of the worm (51) is connected to a handwheel mechanism (54).

7. The high-precision dual-position positioning linear electric actuator according to claim 6, characterized in that: The speed reduction transmission mechanism (5) further includes a sun gear (55), several planetary gears (56), a gear ring (57), a planetary shaft (58), and a planetary constellation (59); the sun gear (55) is integrally connected to the turbine (52) and located below the turbine (52), and the sun gear (55) meshes with each of the planetary gears (56); the gear ring (57) is fixed in the housing (1) and meshes with each of the planetary gears (56); the planetary shaft (58) is installed at the center of each of the planetary gears (56) and passes through the planetary constellation (59), driving the planetary constellation (59) to rotate; the planetary constellation (59) is keyed to the central rod (2).

8. The high-precision dual-position positioning linear electric actuator according to claim 1, characterized in that: The central rod (2) has a lead screw section (21) near the bottom and a smooth section (22) near the top. The smooth section (22) passes through the middle cavity (12) and into the lower cavity (13) of the housing (1). The lead screw section (21) is located in the lower cavity (13) of the housing (1). A needle roller bearing (7) is sleeved on the smooth section (22) of the central rod (2). A plane bearing (8) is provided on the upper and lower sides of the needle roller bearing (7). The upper plane bearing (8) is installed in the upper cavity (11) of the housing (1), and the lower plane bearing (8) is installed in the lower cavity (13) of the housing (1). The needle roller bearing (7) is installed in the middle cavity (12) of the housing (1).

9. The high-precision dual-position positioning linear electric actuator according to claim 8, characterized in that: The lead screw section (21) is connected to a nut (9), and the nut (9) is connected to a hollow output assembly (10) to output linear displacement.

10. A position detection method for a linear electric actuator with high-precision dual-position positioning as described in any one of claims 1-9, characterized in that, Includes the following steps: S1: Under the power-on operating state, the drive motor (3) drives the center rod (2) to rotate through the reduction transmission mechanism (5); the Hall sensor assembly (4) detects the position of the magnet of the rotor of the drive motor (3) in real time to realize the first position detection; S2: The center rod (2) drives the output gear (61) to rotate synchronously, the output gear (61) drives the first encoding gear (62) and the first encoding gear (62) drives the second encoding gear (63); the first magnetic angle sensor (66) detects the rotation angle of the first magnet (64), and the second magnetic angle sensor (67) detects the rotation angle of the second magnet (65); S3: Based on the angle values ​​detected by the first magnetic angle sensor (66) and the second magnetic angle sensor (67), and combined with the difference in the number of teeth between the first coding gear (62) and the second coding gear (63), the number of rotations of the first coding gear (62) or the second coding gear (63) is calculated, and the absolute rotation position of the center rod (2) is calculated from the number of rotations and the rotation angle of the corresponding coding gear, thereby realizing the second position detection; S4: In the power-off state, the magnetic coupling relationship between the first magnet (64) and the first magnetic angle sensor (66), and between the second magnet (65) and the second magnetic angle sensor (67) remains unchanged, and the magnetic encoder assembly (6) can maintain the current position information without power. If the actuator is rotated by the handwheel mechanism (54) during the power-off period, the two encoding gears drive the corresponding magnets to rotate synchronously, and the magnetic coupling relationship is updated synchronously. S5: After the second power-on, the current angle values ​​of the first magnetic angle sensor (66) and the second magnetic angle sensor (67) are directly read. The current absolute position of the actuator can be obtained by the calculation method in step S3 without recalibrating the stroke.

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