Linear telescopic screw motor with grating-induced detection and control method thereof

Abstract

The application discloses a linear telescopic screw rod motor with grating sensing detection and a control method thereof, and relates to the technical field of motors.The structure comprises a casing, an inner rotor motor, a telescopic rod and a grating sensing assembly; the inner rotor motor is arranged inside the casing and comprises a stator assembly and a rotor assembly; the telescopic rod is arranged through the casing and extends from one end, the telescopic rod is provided with a threaded part, and the rotor assembly is provided with a threaded hole matched with the threaded part; the telescopic rod is provided with a radially extending pin shaft close to the extending end, a sliding groove is correspondingly arranged on the casing, and the pin shaft and the sliding groove are slidingly matched to constrain the circumferential rotation of the telescopic rod; the grating sensing assembly comprises a grating sensor and a light transmission hole arranged on the casing, the light transmission hole is offset to one side of the axial movement path of the telescopic rod, and when the telescopic rod moves to a preset zero position, the pin shaft blocks the light transmission hole, so that the light intensity change of a receiving end generates a zero position electric signal.The application realizes zero position detection through offset light path and pin shaft light blocking, and has the advantages of compact structure, strong oil stain resistance and high reliability.

Description

Technical Field

[0001] This invention relates to the field of linear telescopic motors, and particularly to a linear telescopic screw motor with grating sensing detection and its control method. Background Technology

[0002] A linear telescopic motor is an actuator that converts rotary motion into linear reciprocating motion, and it is widely used in automation equipment, medical devices, smart homes, automotive electronics, and other fields. Among them, the screw-type linear telescopic motor drives the screw to extend and retract along the axial direction by rotating the screw rotor through the screw rotor. It has the advantages of simple structure, high transmission efficiency, and easy control.

[0003] In the field of motor position detection and control, grating encoders and grating rulers are widely used for position sensing. Both operate on similar principles, emitting light through a grating emitter, which then forms bright and dark stripes through a light-blocking device and converts them into electrical signals to achieve position feedback. However, traditional grating rulers and encoders require both a grating light emitter and a separate light-blocking device (such as a grating ruler strip or encoder disk) to function effectively. This significantly limits their use in applications involving micro-motors or where space is limited.

[0004] For position detection of linear telescopic motors, existing technologies mainly have the following problems: (1) Traditional solutions usually require additional light-shielding plate parts to work with the grating sensor. The light path is switched on and off by the light-shielding plate moving with the moving parts, thereby detecting the zero or limit position. This solution increases the number of parts and assembly complexity, increases material and manufacturing costs, and occupies additional axial or radial space, which is not conducive to the miniaturization design of the motor.

[0005] (2) The optical path of the grating sensor is usually arranged on the axial path of the telescopic rod. During the reciprocating extension and retraction process, the telescopic rod can easily carry out the lubricating grease inside the motor and the wear debris generated during operation. These oil stains and debris can easily adhere to the light-transmitting area or the light-shielding plate of the grating sensor, causing the optical path to be blocked or the signal to be attenuated, affecting the accuracy and long-term reliability of zero-position detection.

[0006] (3) The installation position of the grating sensor and the detection structure of the telescopic rod lack integrated design. The grating sensor usually needs to be installed outside the housing or the end cover with the help of an independent bracket. As a result, the relative position accuracy between the grating sensing component and the telescopic rod is limited by the cumulative tolerance of multiple parts, which affects the consistency and reliability of zero-position detection.

[0007] (4) Existing linear telescopic motors typically rely on a single grating sensor or a single physical limit switch for position detection, lacking a dual protection mechanism that combines both. When the grating sensor fails due to contamination, aging, or circuit malfunction, the motor may continue to run because it cannot detect the zero position, leading to overtravel of the telescopic rod, damage to the threaded pair, or even motor burnout.

[0008] (5) When the grating sensor fails to detect the zero position signal for any reason, the existing control strategy usually reports an error and stops the machine directly. It lacks an automatic zero-finding and recovery mechanism, which causes the equipment to be unable to continue working when there is a slight abnormality, reducing the fault tolerance and operating efficiency of the system.

[0009] To address the aforementioned issues, there is an urgent need to improve existing linear telescopic screw motors with grating-based sensing and their control methods. Summary of the Invention

[0010] The first objective of this invention is to provide a linear telescopic screw motor with grating induction detection, which solves the problems of existing grating position detection schemes requiring additional light-shielding plates, resulting in large space occupation and numerous parts, as well as the problem that lubricating grease and wear debris brought out by the reciprocating motion of the telescopic rod easily contaminate the grating sensing area, causing signal failure. At the same time, by offsetting the light-transmitting hole to one side of the axial movement path of the telescopic rod and using a pin as a light-shielding element, the grating sensing light path is kept away from the oil-stained area. Double protection is formed by adding a physical limit that lags behind the grating sensing position. The rotor integrity and concentricity are improved by the integral injection molding of the double magnetic ring and the threaded sleeve insert. Thus, while reducing the number of parts, lowering costs, and making the structure more compact, the zero-position detection accuracy, oil resistance, and motor operation reliability are improved.

[0011] The technical solution for achieving the first objective of this invention is: a linear telescopic screw motor with grating sensing detection, comprising a housing, an inner rotor motor, and a telescopic rod; the inner rotor motor is disposed inside the housing, and includes a stator assembly and a rotor assembly rotatably disposed within the stator assembly; the telescopic rod is axially movable through the housing, with one end extending out of the housing; the telescopic rod is provided with a threaded portion; the rotor assembly has a threaded hole that mates with the threaded portion, and when the rotor assembly rotates, the telescopic rod is driven to extend and retract axially through the engagement of the threaded hole and the threaded portion; characterized in that: It also includes a grating sensing component, which includes a grating sensor and a light-transmitting hole opened on the housing; The grating sensor is fixedly mounted on the housing, and the transmitting end and receiving end of the grating sensor are located on both sides of the light-transmitting hole on the housing, respectively. The detection light emitted by the transmitting end passes through the light-transmitting hole and is received by the receiving end. The telescopic rod is fixed with a radially extending pin at one end near the end extending out of the housing. The housing is correspondingly provided with a sliding groove extending in the axial telescopic direction. The pin is embedded in the sliding groove and slides with it to constrain the circumferential rotation of the telescopic rod, so that the telescopic rod can only telescopically extend and retract in a straight axial direction. The light-transmitting hole is offset on one side of the axial movement path of the telescopic rod on the housing, and the light-transmitting hole and the axial movement path of the pin shaft overlap at least partially; when the telescopic rod moves axially to the preset zero position, the pin shaft faces the light-transmitting hole and blocks the light path of the detection light, so that the receiving end cannot receive the detection light or the intensity of the received light changes, thereby generating a zero-position induced electrical signal.

[0012] Preferably, the outer surfaces of the telescopic rod and the pin are subjected to a blackening treatment to reduce the interference of reflection of detection light on the surface of the telescopic rod.

[0013] Preferably, the aperture of the aforementioned light-transmitting hole is configured such that when the telescopic rod moves to a preset zero position, the receiving end can receive a light signal sufficient to trigger zero-position sensing within the response time of the grating sensor.

[0014] Preferably, the end of the slide groove is provided with a limiting part for preventing the pin on the telescopic rod from sliding out of the slide groove; the limiting trigger position of the limiting part lags behind the zero sensing position of the grating sensor in the axial movement direction of the telescopic rod, and a safety gap of 0.1mm~0.3mm is reserved between the two.

[0015] Preferably, the aforementioned housing includes a main housing and an output end cover. The main housing and the output end cover cooperate to form a mounting cavity for accommodating an internal rotor motor. The output end cover is provided with a first bearing chamber, and the main housing is provided with a second bearing chamber at the end away from the output end cover. One end of the rotor assembly is rotatably supported on the output end cover by a first bearing located in the first bearing chamber, and the other end is rotatably supported on the main housing by a second bearing located in the second bearing chamber. The output end cover is provided with an axially extending groove. One end of the telescopic rod extends out of the housing through the groove, and the pin on the telescopic rod is embedded in the groove and slides with the groove to constrain the circumferential rotation of the telescopic rod.

[0016] Furthermore, the aforementioned output end cover includes a main end cover and a press-fit limiting member; the main end cover is coaxially and fixedly connected to the main housing, and a conformal press-fit hole is provided on the main end cover, the conformal press-fit hole penetrating the main end cover axially; the press-fit limiting member includes a pressed part and a protruding part, the radial dimension of the pressed part is larger than the radial dimension of the protruding part; the protruding part passes through the conformal press-fit hole and protrudes from the main end cover, the inner circumferential surface of the conformal press-fit hole conformally engages with the outer circumferential surface of the protruding part to constrain the circumferential rotation of the press-fit limiting member; The press-fitted part abuts against the end face of the first bearing, and the first bearing is pressed into the first bearing chamber through the end face of the main end cover forming a conformal press-fitting hole; the protruding part is provided with a guide hole through the axial direction, and the two sides of the guide hole are respectively provided with axially extending sliding grooves, which are connected to the guide hole; the telescopic rod passes through the guide hole and extends out of the housing, and the pin fixedly installed on the telescopic rod passes through the guide hole and is embedded in the sliding groove. The pin and the sliding groove are slidably engaged to constrain the circumferential rotation of the telescopic rod; a light-transmitting hole is opened on the protruding part offset to one side of the telescopic rod axis, and the grating sensor is fixedly connected to the press-fitting limiting member, and the transmitting end and receiving end of the grating sensor are respectively arranged on both sides of the light-transmitting hole.

[0017] Preferably, the guide hole comprises a large hole and a small hole in sequence from the inside to the outside along the axial direction, and the large hole and the small hole are connected; the inner diameter of the large hole is larger than the outer diameter of the threaded part of the telescopic rod; the inner diameter of the small hole is smaller than the outer diameter of the threaded part but larger than the outer diameter of the rest of the telescopic rod except for the threaded part, so that the threaded part is confined outside the small hole and cannot enter the small hole; a stepped end face is formed at the junction of the large hole and the small hole, and the stepped end face is used to scrape off the lubricating medium attached to the surface of the threaded part and block it on one side of the large hole when the telescopic rod extends and retracts, so as to prevent the lubricating medium from entering the small hole and reaching the detection area of ​​the grating sensor; the sliding groove is provided on both sides of the small hole and is connected to the small hole.

[0018] Preferably, the press-fit limiting component is made of plastic.

[0019] Preferably, the rotor assembly includes a rotor housing, a magnetic ring assembly, and a threaded sleeve. The magnetic ring assembly and the threaded sleeve are integrally formed with the rotor housing by insert injection molding. The threaded hole is the inner hole of the threaded sleeve.

[0020] The second objective of this invention is to provide a control method based on the aforementioned linear telescopic motor to address the problem of the lack of a fault-tolerant mechanism in the prior art where the motor directly stops when the grating sensing is abnormal. By automatically controlling the motor to enter a full-stroke reciprocating zero-finding mode until zeroing is successfully achieved when the host computer does not receive the zero-position signal, and verifying whether the motor can stably enter the normal working mode after successful zeroing to quickly determine the motor fault, the zero-position signal is monitored in real time during normal operation and a protective shutdown is executed when the signal is lost, thereby improving the system's fault tolerance and fault location efficiency.

[0021] The second objective of this invention is achieved through the following technical solution: the control method for the linear telescopic motor described above includes the following steps: S1. The motor starts running, and the telescopic rod drives the pin to reciprocate along the axial direction, collecting the feedback signal output by the grating sensor in real time. S2. When the telescopic rod moves to the preset zero position, the pin is directly facing the light-transmitting hole and blocks the detection light emitted by the grating sensor, so that the receiving end cannot receive the detection light or the intensity of the received light changes. The grating sensor generates a zero-position sensing electrical signal and feeds it back to the host computer. After receiving the zero-position signal, the host computer sends a normal operation command to control the motor to enter the normal operation mode. S3. When the grating sensor does not detect the zero position signal, the host computer repeatedly sends the full stroke displacement command of the motor to control the telescopic rod to enter the full stroke reciprocating zero-finding working mode until the grating sensor detects the zero position signal. S4. After the motor successfully finds zero again, the host computer sends a normal operation command to check whether the motor can stably enter the normal operation mode: if it can run normally, the motor is determined to be in normal condition; if it cannot run normally, the motor is determined to have a fault.

[0022] Furthermore, in step S3, when the inner rotor motor fails to find zero within the preset maximum number of reciprocating cycles, the host computer controls the inner rotor motor to stop running and triggers a fault alarm.

[0023] Furthermore, in step S2, after the inner rotor motor enters the normal working mode, the host computer monitors the zero position signal of the telescopic rod in real time through the grating sensor. If the zero position signal is lost during normal operation, it is determined that the inner rotor motor has an abnormality and a protection shutdown is executed.

[0024] Furthermore, in step S2, the specific determination logic for generating the zero-position induced electrical signal is as follows: when the light intensity received by the receiving end is lower than the preset threshold, the grating sensor determines that the pin has blocked the light-transmitting hole and outputs the zero-position induced electrical signal; when the light intensity received by the receiving end is higher than or equal to the preset threshold, it determines that the pin has not blocked the light-transmitting hole and does not output the zero-position induced electrical signal.

[0025] The present invention has the following positive effects: (1) The present invention places the light-transmitting hole on one side of the axial movement path of the telescopic rod and uses the pin fixed on the telescopic rod as a light-shielding element. When the telescopic rod moves to the preset zero position, the pin blocks the light-transmitting hole, causing the light intensity to change and generating a zero-position electrical signal. Compared with the traditional solution, which requires opening a light-transmitting hole or setting an additional light-shielding plate on the telescopic rod, the present invention does not require opening a hole on the telescopic rod, thus ensuring the structural integrity of the telescopic rod. At the same time, the grating sensing optical path is offset, so that the grating sensor is far away from the friction area where the telescopic rod and the housing meet. The lubricating grease and wear debris brought out by the reciprocating motion of the telescopic rod are not easy to reach the grating sensing area, which greatly reduces the risk of signal failure caused by oil pollution.

[0026] (2) In this invention, the pin shaft simultaneously performs dual functions: it serves as an anti-rotation guide element that cooperates with the slide groove to constrain the circumferential rotation of the telescopic rod, and it also serves as a light-shielding element for grating sensing to achieve zero-position detection. This dual-purpose design reduces the number of parts, material costs, and assembly complexity.

[0027] (3) In this invention, the transmitting end and receiving end of the grating sensor are respectively set on both sides of the light-transmitting hole, the optical path is short and fixed, and is not affected by the movement of the telescopic rod, so the signal stability is good. The internal rotor motor and the telescopic rod are directly driven by threaded connection, the transmission chain is short and the efficiency is high, and the overall structure is compact.

[0028] (4) In this invention, the surface reflectivity of the telescopic rod and pin is significantly reduced after blackening treatment, which can effectively reduce the reflection and scattering of detection light on the surface of the telescopic rod and pin, and avoid the reflected light being mistakenly received by the receiving end to form an interference signal, thereby improving the signal-to-noise ratio of the grating sensing signal and the accuracy of zero-position detection. In particular, as a direct light-shielding element, the blackening treatment of the pin's surface can enhance the absorption of detection light, further improving the light-shielding effect and the reliability of zero-position triggering.

[0029] (5) By rationally configuring the aperture of the light-transmitting hole, the present invention ensures that when the telescopic rod moves at high speed through the zero position, the pin shaft blocks the light-transmitting hole so that the change in light intensity at the receiving end can be effectively detected within the response time of the grating sensor, thus taking into account both the reliability of zero-position detection and the high-speed operation requirements of the motor; at the same time, it avoids the problem that the aperture is too large, which would make it easy for oil or debris to enter the optical path area, thus achieving an optimized balance between detection performance and anti-fouling capability.

[0030] (6) In this invention, the limiting part, as a physical limiting component, can forcibly limit the overtravel movement of the telescopic rod when the grating sensing is abnormal or fails, preventing the motor from being damaged due to loss of control, thus forming a dual protection mechanism of "grating sensing + physical limiting". The trigger position of the limiting part lags behind the zero-position sensing position of the grating and reserves a safety gap of 0.1mm~0.3mm, ensuring that the limiting part will not be falsely triggered under normal working conditions, while ensuring timely intervention before overtravel damage occurs under abnormal conditions, thus taking into account both the smoothness of normal operation and the effectiveness of abnormal protection.

[0031] (7) In this invention, the press-fit limiting component is a multifunctional integrated part that simultaneously achieves three major functions: pressing the first bearing by the press-fitted part, guiding the linear movement of the telescopic rod and preventing rotation by the guide hole and slide groove of the protrusion, and realizing zero-position detection by the light-transmitting hole and grating sensor mounting structure on the protrusion. One part replaces multiple parts such as the bearing pressure plate, guide sleeve, and grating bracket in the traditional solution, greatly reducing the number of parts and assembly steps, and lowering costs. The conformal fit between the conformal press-fitting hole and the outer circumferential surface of the protrusion constrains the circumferential rotation of the press-fit limiting component, ensuring the angular positioning accuracy of the light-transmitting hole and the grating sensor, and ensuring the consistency of zero-position detection. The separate structure of the main end cover and the press-fit limiting component facilitates disassembly and maintenance, improving the maintainability of the product.

[0032] (8) The stepped end face formed by the variable diameter design of the large and small holes of the guide hole in this invention can scrape off the lubricating grease and wear debris adhering to the surface of the threaded part and block it on the side of the large hole when the telescopic rod extends and retracts, preventing it from following the telescopic rod into the small hole and further reaching the detection area of ​​the grating sensor. This structure does not require additional sealing rings or other parts; it can achieve efficient oil scraping and dirt blocking function simply by changing the diameter of the structure, further improving the anti-oil and dirt resistance of the grating sensor and ensuring long-term reliability. At the same time, the small hole restricts the entry of the threaded part, ensuring that only the smooth rod part protrudes from the housing, reducing the friction area of ​​the extended section of the telescopic rod, which helps to reduce movement resistance.

[0033] (9) The press-fit limiting component in this invention is made of plastic, which is lightweight, low-cost, and easy to process and mold, making it particularly suitable for mass production of irregularly shaped structures such as contour press-fit holes. The plastic press-fit limiting component has a low coefficient of friction when it is used with the metal telescopic rod, which helps to reduce the movement resistance and wear of the telescopic rod. At the same time, the plastic part is not magnetic and will not interfere with the magnetic field or optical path of the grating sensor, thus ensuring the signal quality of the grating sensing.

[0034] (10) In this invention, the magnetic ring assembly and the threaded sleeve are integrally formed with the rotor housing through insert injection molding, which reduces the number of parts and assembly steps, improves the integrity and concentricity of the rotor, and reduces manufacturing costs. The threaded hole is directly formed in the inner hole of the threaded sleeve. The internal thread has high precision and good wear resistance, and can withstand frequent telescopic loads, thus extending the service life of the motor. The magnetic ring assembly can adopt a double magnetic ring or multi-magnetic ring structure, which can improve the output of the effective magnetic flux of the motor, reduce the interference of ineffective magnetic flux on the motor, and make the motor operation more stable.

[0035] (11) In this invention, the control method achieves precise position control of the motor through the zero-position signal of the grating sensor. Combined with the pulse control of the stepper motor, the position of the motor can be calculated in real time, achieving high-precision extension and retraction control. When the grating sensor does not detect the zero-position signal, the motor automatically enters the full-stroke reciprocating zero-finding working mode until zeroing is successful, possessing automatic recovery capability and improving the intelligence level of the system. After successful zeroing, the system verifies whether the motor can stably enter the normal working mode by sending a normal working command, which can quickly identify whether there is a fault in the motor and facilitate timely problem location. The complete "start → zeroing → verification → judgment" control logic ensures that the zero-position state can be confirmed every time the motor starts, avoiding control errors caused by zero-position loss.

[0036] (12) In this invention, a maximum reciprocating number threshold is set. When the motor fails to find zero within the set number of times, it will automatically stop and alarm, avoiding energy waste and mechanical wear caused by the motor running indefinitely. At the same time, it will promptly prompt the operator to troubleshoot the fault, thus improving the safety and maintainability of the system.

[0037] (13) The present invention continuously monitors the zero position signal in normal working mode, realizing real-time monitoring of the motor operating status; once the zero position signal is abnormally lost, the protection shutdown is immediately executed to prevent the motor from continuing to run in an uncontrolled state, causing equipment damage or safety accidents, thereby improving the safety and reliability of motor operation.

[0038] (14) This invention avoids signal jitter caused by light source fluctuations, ambient light interference, or device aging by setting a light intensity threshold as the criterion for zero-position triggering, thereby improving the anti-interference capability and judgment accuracy of zero-position detection. The judgment logic is simple and reliable, and easy to implement in microcontrollers or dedicated driver chips, which helps to reduce the hardware cost of the control system. Attached Figure Description

[0039] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein... Figure 1 This is a schematic diagram of the linear telescopic screw motor in this invention; Figure 2 This is a cross-sectional view of the linear telescopic screw motor in this invention; Figure 3 This is an exploded view of the linear telescopic screw motor in this invention; Figure 4 This is a schematic diagram of the press-fit limiting component in this invention; Figure 5 This is a cross-sectional view of the press-fit limiting member in this invention; Figure 6 This is a schematic diagram of the installation of the grating sensing component in this invention; Figure 7 This is a schematic diagram of the telescopic rod in this invention; In the diagram, 1—housing; 11—main housing; 111—second bearing chamber; 12—output end cover; 121—first bearing chamber; 122—main end cover; 1221—contour pressing hole; 123—pressing limiter; 1231—pressed part; 1232—protruding part; 1233—guide hole; 1233a—large hole; 1233b—small hole; 1233c—stepped end face; 1234—slide groove; 1235—limiter. 2—Internal rotor motor; 21—Stator assembly; 211—Stator core; 212—Stator winding; 22—Rotor assembly; 221—Magnetic ring assembly; 222—Threaded bushing; 3—Telescopic rod; 31—Threaded part; 32—Pin; 41—First bearing; 42—Second bearing; 5—Grating sensing component; 51—Grating sensor; 511—Transmitter; 512—Receiver; 52—Light-transmitting aperture. Detailed Implementation

[0040] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0041] like Figures 1 to 7 As shown, the present invention provides a linear telescopic screw motor with grating sensing detection, comprising a housing 1, an inner rotor motor 2, and a telescopic rod 3.

[0042] like Figures 1 to 3 As shown, the housing 1 includes a main housing 11 and an output end cover 12. The main housing 11 has a sleeve-like structure, and the output end cover 12 is disposed at one end of the main housing 11. Figure 2 As shown at the upper end), the main housing 11 and the output end cover 12 cooperate to form a mounting cavity for accommodating the internal rotor motor 2. The output end cover 12 is provided with a first bearing chamber 121, and the end of the main housing 11 furthest from the output end cover 12 (… Figure 2 The lower end shown is provided with a second bearing chamber 111.

[0043] In a preferred embodiment, the output end cover 12 includes a main end cover 122 and a press-fit limiting member 123. The main end cover 122 is coaxially fixedly connected to the main housing 11 (e.g., by screws). A contoured press-fit hole 1221 is provided on the main end cover 122, extending axially through the main end cover 122. The contoured press-fit hole 1221 is a non-circular hole that matches the shape of the outer circumferential surface of the protrusion 1232 of the press-fit limiting member 123. In this embodiment, an irregularly shaped hole is used (see...). Figure 1 or Figure 3 , or see Figure 4 (The outer circumferential surface shape of the pressure limiting component 123), of course, other hole shapes are also possible, such as waist-shaped holes, D-shaped holes or polygonal holes, etc.

[0044] See Figure 4 and Figure 5 The press-fit limiting member 123 includes a press-fit portion 1231 and a protruding portion 1232. The radial dimension of the press-fit portion 1231 is larger than that of the protruding portion 1232, forming a stepped structure between them. The protruding portion 1232 passes through the conformal press-fit hole 1221 and extends out of the main end cover 122. The inner circumferential surface of the conformal press-fit hole 1221 conformally engages with the outer circumferential surface of the protruding portion 1232 to constrain the circumferential rotation of the press-fit limiting member 123. The press-fit portion 1231 abuts against the end face of the first bearing 41, and the stepped end face of the conformal press-fit hole 1221 on the main end cover 122 presses the first bearing 41 into the first bearing chamber 121. This structure allows the press-fit limiting member 123 to achieve both axial and circumferential positioning after installation, without the need for additional fasteners.

[0045] The press-fit limiting component 123 is preferably a plastic part (such as POM, PA66 and other engineering plastics), which is lightweight, low cost, easy to process and mold, and has a low coefficient of friction when it is used with the metal telescopic rod 3, which helps to reduce movement resistance.

[0046] like Figure 2 As shown, the internal rotor motor 2 is disposed inside the mounting cavity of the housing 1. The internal rotor motor 2 includes a stator assembly 21 and a rotor assembly 22 rotatably disposed within the stator assembly 21.

[0047] The stator assembly 21 includes a stator core 211 and a stator winding 212. The stator assembly 21 is coaxially arranged with the rotor assembly 22.

[0048] The rotor assembly 22 includes a rotor housing, a magnetic ring assembly 221, and a threaded sleeve 222. Both the magnetic ring assembly 221 and the threaded sleeve 222 are integrally molded with the rotor housing using insert injection molding, reducing the number of parts and assembly steps, and improving the overall integrity and concentricity of the rotor assembly 22. The magnetic ring assembly 221 may include a first magnetic ring and a second magnetic ring arranged axially at intervals (i.e., a double magnetic ring structure), forming an optimized magnetic circuit distribution. This improves the output of the effective magnetic flux of the motor, reduces the interference of ineffective magnetic flux on the motor, and makes the motor operation more stable. The inner hole of the threaded sleeve 222 is provided with an internal thread, which is the threaded hole that mates with the threaded portion 31 of the telescopic rod 3.

[0049] One end of the rotor assembly 22 is rotatably supported on the output end cover 12 by a first bearing 41 located in the first bearing chamber 121, and the other end is rotatably supported on the main housing 11 by a second bearing 42 located in the second bearing chamber 111. The dual bearing support structure ensures the smoothness and concentricity of the rotor assembly 22's rotation, reducing operating vibration and noise.

[0050] like Figure 2 , Figure 6 , Figure 7 As shown, the telescopic rod 3 is axially movable through the housing 1, with one end of the telescopic rod 3 extending outside the output end cover 12 of the housing 1. The telescopic rod 3 is provided with a threaded part 31, and the internal thread of the threaded sleeve 222 of the rotor assembly 22 engages with the threaded part 31. When the rotor assembly 22 of the inner rotor motor 2 rotates, the telescopic rod 3 is driven to extend and retract axially through the engagement of the threaded hole (the internal thread of the threaded sleeve 222) and the threaded part 31.

[0051] A radially extending pin 32 is fixed to one end of the telescopic rod 3 near the end extending from the housing 1. The pin 32 can be fixed to the telescopic rod 3 by riveting, welding, or threading. The outer surfaces of both the telescopic rod 3 and the pin 32 are blackened to reduce interference from the reflection of detection light on their surfaces.

[0052] The protruding portion 1232 of the press-fit limiting member 123 has a guide hole 1233 extending through it axially. A sliding groove 1234 extending axially is provided on both sides of the guide hole 1233, and the sliding groove 1234 communicates with the guide hole 1233. The telescopic rod 3 passes through the guide hole 1233 and extends out of the housing 1. A pin 32 fixedly mounted on the telescopic rod 3 passes through the guide hole 1233 and is embedded in the sliding groove 1234. The pin 32 and the sliding groove 1234 are in sliding engagement to constrain the circumferential rotation of the telescopic rod 3, so that the telescopic rod 3 can only perform linear telescopic movement along the axial direction and does not rotate with the rotor assembly 22.

[0053] In a preferred embodiment, the guide hole 1233 includes a large hole portion 1233a and a small hole portion 1233b sequentially along the axial direction from the inside to the outside (i.e., from the rotor assembly 22 towards the extension rod 3 extending out of the housing 1). The large hole portion 1233a and the small hole portion 1233b are connected. The inner diameter of the large hole portion 1233a is larger than the outer diameter of the threaded portion 31 of the extension rod 3, allowing the threaded portion 31 to move freely within the large hole portion 1233a. The inner diameter of the small hole portion 1233b is smaller than the outer diameter of the threaded portion 31 but larger than the outer diameter of the rest of the extension rod 3 (i.e., the smooth rod portion), confining the threaded portion 31 outside the small hole portion 1233b and preventing it from entering the small hole portion 1233b. A stepped end face 1233c is formed at the junction of the large hole portion 1233a and the small hole portion 1233b. This stepped end face 1233c is used to scrape off the lubricating medium adhering to the surface of the threaded portion 31 and block it on the side of the large hole portion 1233a when the telescopic rod 3 extends or retracts, so as to prevent the lubricating medium from entering the small hole portion 1233b and reaching the detection area of ​​the grating sensor 51. The slide groove 1234 is provided on both sides of the small hole portion 1233b and is connected to the small hole portion 1233b.

[0054] The end of the chute 1234 ( Figure 2 The upper end shown is provided with a limiting part 1235 (i.e., the slide groove 1234 is located at the upper end). Figure 2 (As shown in the diagram, the upper end forms a sealed portion), the limiting part 1235 is used to prevent the pin 32 on the telescopic rod 3 from sliding out of the slide groove 1234. The limiting trigger position of the limiting part 1235 lags behind the zero-position sensing position of the grating sensor 51 in the axial movement direction of the telescopic rod 3, and a safety gap of 0.1mm to 0.3mm is reserved between the two to ensure that the limiting part 1235 will not be falsely triggered under normal working conditions.

[0055] like Figure 1 , Figure 2 , Figure 3 , Figure 6 As shown, the present invention also includes a grating sensing component 5. The grating sensing component 5 includes a grating sensor 51 and a light-transmitting hole 52 formed on the protrusion 1232 of the press-fit limiting member 123.

[0056] The light-transmitting hole 52 is offset on one side of the axis of the telescopic rod 3 on the protrusion 1232, and the axial movement path of the light-transmitting hole 52 at least partially overlaps with that of the pin 32. The grating sensor 51 is fixedly connected to the press-fit limiting member 123 (e.g., by screw connection or snap-fit ​​connection). The emitting end 511 and the receiving end 512 of the grating sensor 51 are respectively disposed on both sides of the light-transmitting hole 52. The detection light emitted by the emitting end 511 passes through the light-transmitting hole 52 and is received by the receiving end 512.

[0057] When the telescopic rod 3 extends and retracts axially to the preset zero position, the pin 32 faces the light-transmitting hole 52 and blocks the light path of the detection light, so that the receiving end 512 does not receive the detection light or the intensity of the received light changes, thereby generating a zero-position induced electrical signal. This zero-position induced electrical signal is transmitted to a host computer (such as a PLC, microcontroller, or dedicated motor driver) for zero-position identification and control of the motor.

[0058] In a preferred embodiment, the grating sensor 51 has a protective housing, and both the transmitting end 511 and the receiving end 512 of the grating sensor 51 are fixedly installed inside the protective housing. The protective housing is fitted onto the press-fit limiting member 123 and is fixedly connected to the main end cover 122 by bolts. See also Figure 1 and Figure 3 .

[0059] The control method based on the above-mentioned linear telescopic screw motor specifically includes the following steps: S1. Motor start-up and signal acquisition steps: The motor starts running. After the motor starts, the telescopic rod 3 drives the pin shaft 32 to reciprocate along the axial direction. The host computer (such as a PLC, microcontroller, or dedicated motor driver) collects the feedback signal output by the grating sensor 51 in real time. Specifically, the emitting end 511 of the grating sensor 51 continuously emits detection light, and the receiving end 512 detects in real time whether it receives the detection light passing through the light-transmitting hole 52, and converts the received result (light intensity signal) into an electrical signal and transmits it to the host computer.

[0060] Under normal conditions (when pin 32 does not block the light-transmitting hole 52), receiver 512 can continuously receive the detection light emitted by transmitter 511, at which time grating sensor 51 outputs a high-level signal. The host computer monitors the changes in this level signal in real time.

[0061] S2, Zero Position Judgment and Normal Working Mode Entry Steps: The host computer determines in real time whether the telescopic rod 3 has moved to the preset zero position (i.e., whether the pin 32 blocks the light-transmitting hole 52, causing a change in the light intensity of the receiver 512).

[0062] When the telescopic rod 3 moves to the preset zero position, the pin 32 faces the light-transmitting hole 52 and blocks the detection light emitted by the transmitter 511 of the grating sensor 51, causing the receiver 512 to not receive the detection light or to change the intensity of the received light. Specifically, when the light intensity received by the receiver 512 is lower than the preset threshold, the grating sensor 51 determines that the pin 32 has blocked the light-transmitting hole 52 and outputs a zero-position sensing electrical signal (such as a low-level signal) to the host computer; when the light intensity received by the receiver 512 is higher than or equal to the preset threshold, it determines that the pin 32 has not blocked the light-transmitting hole 52 and does not output a zero-position sensing electrical signal.

[0063] Testing revealed that when pin 32 did not block the light-transmitting hole 52, the voltage output by receiver 512 was 3.0V~3.3V; when pin 32 completely blocked the light-transmitting hole 52, the output voltage dropped below 0.2V. Based on this, a preset threshold was set to 1.5V: when the output voltage of receiver 512 was below 1.5V, it was determined that pin 32 had blocked the light-transmitting hole 52, and a zero-position induced electrical signal was output; when the output voltage was above or equal to 1.5V, it was determined that pin 32 did not block the light-transmitting hole 52, and no zero-position induced electrical signal was output.

[0064] After receiving the zero-position signal, the host computer sends a normal operation command to control the motor to enter the normal operation mode, and the telescopic rod 3 begins to perform normal telescopic operations.

[0065] In normal operating mode, the host computer monitors the zero-position signal of the telescopic rod 3 in real time through the grating sensor 51. If the zero-position signal is lost during normal operation, it is determined that the motor is abnormal, and the host computer immediately executes a protective shutdown.

[0066] S3. Zero-finding steps when zero position is not detected: When the grating sensor 51 does not detect the zero position signal (i.e., the light intensity received by the receiver 512 is always higher than the preset threshold, indicating that the pin 32 does not block the light-transmitting hole 52), it indicates that the telescopic rod 3 is not currently in the preset zero position. At this time, the host computer repeatedly sends the full-stroke motion displacement command of the motor to control the telescopic rod 3 to enter the full-stroke reciprocating zero-finding working mode until the grating sensor 51 detects the zero position signal.

[0067] Specifically, the full-stroke reciprocating zero-finding working mode includes: the host computer sending a full-stroke motion displacement command to control the telescopic rod 3 to move from its current actual position to one side mechanical limit endpoint (e.g., Figure 2 The upper limit stop 1235 or the lower mechanical limit stop shown in the figure is then moved in the opposite direction from the mechanical limit stop end to the other mechanical limit stop end, thus performing a full-stroke reciprocating motion. Through the full-stroke reciprocating motion, it is ensured that the telescopic rod 3 can traverse the entire stroke range during the zeroing process, and the pin 32 will definitely pass through the light-transmitting hole 52 position, avoiding missed detection due to the starting position being close to the zero position, and improving the success rate of zeroing.

[0068] As a preferred implementation, when the motor fails to find zero within a preset maximum number of reciprocating cycles (e.g., 3 cycles), the host computer controls the motor to stop running and triggers a fault alarm to avoid energy waste and mechanical wear caused by the motor running indefinitely.

[0069] S4. Steps for verifying successful change and troubleshooting: Once the motor successfully zeros itself, the host computer sends a normal operation command to check if the motor can stably enter the normal operation mode. Specifically, the host computer controls the motor to run according to a preset detection mode (such as "CW-CCW-CW mode" or a test mode calibrated according to the actual working conditions).

[0070] If the motor can run stably and normally according to the normal operating instructions, the motor is considered to be in normal condition; otherwise, if the motor cannot run according to the normal operating instructions or loses the zero position signal again during the test operation, the motor is considered to be faulty, and the host computer will trigger a fault alarm.

[0071] S5. Physical limit protection procedure: During motor operation (including normal operating mode and reciprocating zeroing mode), if the grating sensor malfunctions (such as contamination, aging, or circuit failure of the grating sensor 51), and the motor fails to sense the zero position or the sensing time exceeds the preset threshold, the limit unit 1235 is triggered as a physical limit component. This forcibly restricts the overtravel movement of the telescopic rod 3. The limit unit 1235 continues to slide through the blocking pin 32, preventing the telescopic rod 3 from continuing to move in the extension direction and thus preventing damage to the motor structure. As the last line of defense in the control method, the physical limit protection step can still function independently even in the extreme case of complete failure of the grating sensor 51, greatly improving the reliability and safety of the motor.

[0072] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A linear telescopic screw motor with grating sensing detection, comprising a housing, an inner rotor motor, and a telescopic rod; the inner rotor motor is disposed inside the housing, and includes a stator assembly and a rotor assembly rotatably disposed within the stator assembly; the telescopic rod is axially movable through the housing, with one end extending out of the housing; the telescopic rod is provided with a threaded portion; the rotor assembly has a threaded hole that mates with the threaded portion, and when the rotor assembly rotates, the telescopic rod is driven to extend and retract axially through the engagement of the threaded hole and the threaded portion; characterized in that: It also includes a grating sensing component, which includes a grating sensor and a light-transmitting hole opened on the housing; The grating sensor is fixedly mounted on the housing, and the transmitting end and receiving end of the grating sensor are located on both sides of the light-transmitting hole on the housing, respectively. The detection light emitted by the transmitting end passes through the light-transmitting hole and is received by the receiving end. The telescopic rod is fixed with a radially extending pin at one end near the end extending out of the housing. The housing is correspondingly provided with a sliding groove extending in the axial telescopic direction. The pin is embedded in the sliding groove and slides with it to constrain the circumferential rotation of the telescopic rod, so that the telescopic rod can only telescopically extend and retract in a straight axial direction. The light-transmitting hole is offset on one side of the axial movement path of the telescopic rod on the housing, and the light-transmitting hole at least partially overlaps with the axial movement path of the pin. When the telescopic rod extends and retracts axially to the preset zero position, the pin is aligned with the light-transmitting hole and blocks the light path of the detection light, so that the receiving end cannot receive the detection light or the intensity of the received light changes, thereby generating a zero-position induced electrical signal.

2. The linear telescopic screw motor with grating sensing detection according to claim 1, characterized in that: The outer surfaces of the telescopic rod and the pin are all blackened to reduce the interference of reflected light from the detection light on the surface of the telescopic rod.

3. The linear telescopic screw motor with grating sensing detection according to claim 1, characterized in that: The aperture of the light-transmitting hole is configured such that when the telescopic rod moves to a preset zero position, the receiving end can receive a light signal sufficient to trigger the zero-position sensing within the response time of the grating sensor.

4. The linear telescopic screw motor with grating sensing detection according to claim 1, characterized in that: The end of the slide is provided with a limiting part to prevent the pin on the telescopic rod from sliding out of the slide; the limiting trigger position of the limiting part lags behind the zero sensing position of the grating sensor in the axial movement direction of the telescopic rod, and a safety gap of 0.1mm~0.3mm is reserved between the two.

5. The linear telescopic screw motor with grating sensing detection according to claim 1, 2, 3, or 4, characterized in that: The housing includes a main housing and an output end cover. The main housing and the output end cover cooperate to form a mounting cavity for accommodating an internal rotor motor. The output end cover is provided with a first bearing chamber, and the main housing is provided with a second bearing chamber at the end away from the output end cover. One end of the rotor assembly is rotatably supported on the output end cover by a first bearing located in the first bearing chamber, and the other end is rotatably supported on the main housing by a second bearing located in the second bearing chamber. The output end cover is provided with an axially extending groove. One end of the telescopic rod extends out of the housing through the groove, and the pin on the telescopic rod is embedded in the groove and slides with the groove to constrain the circumferential rotation of the telescopic rod.

6. The linear telescopic screw motor with grating sensing detection according to claim 5, characterized in that: The output end cover includes a main end cover and a press-fit limiting member; the main end cover is coaxially fixedly connected to the main housing, and a conformal press-fit hole is provided on the main end cover, the conformal press-fit hole penetrating the main end cover axially; the press-fit limiting member includes a pressed part and a protruding part, the radial dimension of the pressed part is larger than the radial dimension of the protruding part; the protruding part passes through the conformal press-fit hole and protrudes from the main end cover, the inner circumferential surface of the conformal press-fit hole conformally engages with the outer circumferential surface of the protruding part to constrain the circumferential rotation of the press-fit limiting member; The press-fitted part abuts against the end face of the first bearing, and the first bearing is pressed into the first bearing chamber through the end face of the main end cover forming a conformal press-fitting hole; the protruding part is provided with a guide hole through the axial direction, and the two sides of the guide hole are respectively provided with axially extending sliding grooves, which are connected to the guide hole; the telescopic rod passes through the guide hole and extends out of the housing, and the pin fixedly installed on the telescopic rod passes through the guide hole and is embedded in the sliding groove. The pin and the sliding groove are slidably engaged to constrain the circumferential rotation of the telescopic rod; a light-transmitting hole is opened on the protruding part offset to one side of the telescopic rod axis, and the grating sensor is fixedly connected to the press-fitting limiting member, and the transmitting end and receiving end of the grating sensor are respectively arranged on both sides of the light-transmitting hole.

7. The linear telescopic screw motor with grating sensing detection according to claim 6, characterized in that: The guide hole includes a large hole and a small hole in sequence from the inside to the outside along the axial direction. The large hole and the small hole are connected. The inner diameter of the large hole is larger than the outer diameter of the threaded part of the telescopic rod. The inner diameter of the small hole is smaller than the outer diameter of the threaded part but larger than the outer diameter of the rest of the telescopic rod except for the threaded part, so that the threaded part is confined outside the small hole and cannot enter the small hole. A stepped end face is formed at the junction of the large hole and the small hole. The stepped end face is used to scrape off the lubricating medium attached to the surface of the threaded part and block it on one side of the large hole when the telescopic rod is extended or retracted, so as to prevent the lubricating medium from entering the small hole and reaching the detection area of ​​the grating sensor. The sliding groove is provided on both sides of the small hole and is connected to the small hole.

8. The linear telescopic screw motor with grating sensing detection according to claim 6, characterized in that: The press-fit limiting component is made of plastic.

9. The linear telescopic screw motor with grating sensing detection according to claim 1, characterized in that: The rotor assembly includes a rotor housing, a magnetic ring assembly, and a threaded sleeve. The magnetic ring assembly and the threaded sleeve are integrally formed with the rotor housing by insert injection molding. The threaded hole is the inner hole of the threaded sleeve.

10. A control method for a linear telescopic motor, based on the linear telescopic screw motor with grating induction detection as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1. The motor starts running, and the telescopic rod drives the pin to reciprocate along the axial direction, collecting the feedback signal output by the grating sensor in real time. S2. When the telescopic rod moves to the preset zero position, the pin is directly facing the light-transmitting hole and blocks the detection light emitted by the grating sensor, so that the receiving end cannot receive the detection light or the intensity of the received light changes. The grating sensor generates a zero-position sensing electrical signal and feeds it back to the host computer. After receiving the zero-position signal, the host computer sends a normal operation command to control the motor to enter the normal operation mode. S3. When the grating sensor does not detect the zero position signal, the host computer repeatedly sends the full stroke displacement command of the motor to control the telescopic rod to enter the full stroke reciprocating zero-finding working mode until the grating sensor detects the zero position signal. S4. After the motor successfully finds zero again, the host computer sends a normal operation command to check whether the motor can stably enter the normal operation mode: if it can run normally, the motor is determined to be in normal condition. If it cannot operate normally, the motor is considered to be faulty.

11. The control method for a linear telescopic motor according to claim 10, characterized in that: In step S3, if the inner rotor motor fails to find zero within the preset maximum number of reciprocating cycles, the host computer controls the inner rotor motor to stop running and triggers a fault alarm.

12. The control method for a linear telescopic motor according to claim 10, characterized in that: In step S2, after the inner rotor motor enters the normal working mode, the host computer monitors the zero position signal of the telescopic rod in real time through the grating sensor. If the zero position signal is lost during normal operation, it is determined that the inner rotor motor has an abnormality and a protection shutdown is executed.

13. The control method for a linear telescopic motor according to claim 10, characterized in that: In step S2, the specific determination logic for generating the zero-position induced electrical signal is as follows: when the light intensity received by the receiving end is lower than the preset threshold, the grating sensor determines that the pin has blocked the light-transmitting hole and outputs the zero-position induced electrical signal; when the light intensity received by the receiving end is higher than or equal to the preset threshold, it determines that the pin has not blocked the light-transmitting hole and does not output the zero-position induced electrical signal.

Images