A lithium electric wrench dynamic thermal balance management system and an efficiency optimization method based on motor heat loss suppression

Abstract

The application discloses a lithium electric wrench dynamic thermal balance management system and an efficiency optimization method based on motor heat loss inhibition, and the system comprises a shell, a brushless motor, an extension shaft, an axial flow fan, a flow guide structure and a shielding ring. The flow guide structure comprises a conical flow guide umbrella and a swing rod, the caliber of the flow guide umbrella gradually decreases from the tail part to the head part, and the circumferential folding part is provided, the linkage area is provided with a magnetic steel sheet or magnetic powder, and the magnetic steel sheet or magnetic powder interacts with the magnetic leakage field of the motor end part to form a non-contact magnetic spring reset mechanism. The control method adopts a "temperature sensing limited power" architecture: the algorithm calculates the maximum allowable output current according to the winding temperature, and the final output current is the smaller value of the user demand current and the temperature upper limit current. The higher the temperature is, the lower the current upper limit is, and the user perceives that the tool is "gradually losing strength" rather than "suddenly dying", and the task completion degree is ensured while the motor is protected. The application also introduces a temperature rise rate dynamic correction, an impact working condition current limiting enhancement, an LED five-level state feedback, a trigger priority response, a recovery lag and a hardware power-off protection mechanism, and realizes full-level thermal protection from mechanical heat dissipation to software current limiting to hardware power-off.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery wrench motor control and heat dissipation technology, and in particular to a dynamic thermal balance management system for lithium-ion battery wrenches and an efficiency optimization method based on motor heat loss suppression. Background Technology

[0002] Lithium-ion battery wrenches, as an important handheld power tool, are widely used in mechanical assembly, construction, and automotive repair. Their core power source is a brushless motor, which boasts advantages such as high efficiency, long lifespan, and low maintenance costs. However, under heavy-duty continuous operation, the heat generated by copper and iron losses within the brushless motor rises sharply. Poor heat dissipation can lead to problems such as excessively high motor winding temperatures, demagnetization of permanent magnets, and bearing lubrication failure, severely impacting the tool's lifespan and operational safety.

[0003] Existing lithium battery wrench speed control and heat dissipation management solutions have the following main shortcomings: First, there is a fundamental physical contradiction between speed control and heat dissipation management. In existing solutions, users directly control the motor speed by pressing a trigger switch. Under heavy-load, low-speed conditions (such as tightening bolts with high torque), the motor generates the most heat, but the fan speed, air pressure, and heat dissipation are at their lowest, creating an inherent contradiction of "weakest heat dissipation when heat dissipation is most needed." This contradiction is determined by physical laws and cannot be solved by simple speed adjustment.

[0004] Second, existing adaptive cooling solutions suffer from a mismatch between the controlled object and the actuator. Some improved solutions introduce temperature sensors and algorithms, attempting to control heat dissipation by adjusting the motor speed. However, the actual motor speed is determined by both the user's trigger command and the load, and the controller cannot use it as a freely adjustable cooling actuator. When the user requires low-speed, high-torque output, the cooling demand is greatest, but the motor speed is lowest. The algorithm's adjustment space is locked by the user command, rendering it powerless to improve cooling.

[0005] Third, there is a lack of tiered and perceptible thermal protection mechanisms. Existing solutions often resort to sudden power outages or simple speed reductions when temperatures exceed limits, leaving users unprepared for tool failure or power loss, leading to task failure or even workpiece damage. A more reasonable solution should employ tiered current limiting, coupled with clear user notification, to ensure the tool "loses power" rather than "suddenly fails," protecting the motor while maintaining task completion. Summary of the Invention

[0006] To address the problems in the prior art, this invention provides a dynamic thermal equilibrium management system for lithium-ion battery wrenches and an efficiency optimization method based on motor thermal loss suppression.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: A dynamic thermal equilibrium management system for a lithium-ion battery wrench includes a housing, a brushless motor, an extension shaft, an axial fan, a flow guiding structure, and a shielding ring.

[0008] The housing has an air inlet at the rear end and an air outlet on the side. The brushless motor is located inside the housing as a power source.

[0009] The extension shaft is connected to the rotor of the brushless motor and extends to the air inlet side, and the axial fan is mounted on the extension shaft. The heat dissipation blades of the axial fan are located in the outer area. The housing is provided with annular rectifier blades, and the rectification area of ​​the rectifier blades overlaps with the heat dissipation blades in the axial direction. The rectifier blades rectify the airflow generated by the heat dissipation blades in the axial direction and blow it into the guide umbrella.

[0010] The flow guiding structure includes a conical flow guiding umbrella and swing rods mounted on the housing. The diameter of the flow guiding umbrella gradually decreases from the tail to the head, and the umbrella has folded sections arranged in a circumferential array, with the area between each two adjacent folded sections forming a linkage area. The swing rods are evenly distributed in a circumferential array at the folded sections, and the radial swing range of the swing rods forms an angle of 15-30 degrees with the axial direction. A magnet or magnetic powder is provided on the front side of the linkage area, located around the head end of the brushless motor. The magnet or magnetic powder interacts with the leakage magnetic field at the head end of the brushless motor, generating a magnetic attraction force when the flow guiding umbrella is closed. This magnetic attraction force decreases nonlinearly as the air gap increases when the flow guiding umbrella is unfolded. The minimum air gap between the magnetic steel sheet or magnetic powder and the outer shell of the brushless motor head end when the air guide umbrella is fully retracted is 0.5mm~2.0mm, and the maximum air gap between the air guide umbrella and the outer shell of the brushless motor head end end when the air guide umbrella is fully extended is 5.0mm~10.0mm, forming a non-contact magnetic spring reset mechanism. An elastic reset element is provided between the swing rod and the shell. The preload of the elastic reset element is less than the maximum magnetic attraction force generated by the magnetic steel sheet or magnetic powder in the retracted state of the air guide umbrella, and greater than the airflow resistance experienced by the air guide umbrella in the fully extended state.

[0011] The shielding ring is located on the periphery of the tail end of the brushless motor. The shielding ring is a closed ring structure made of high magnetic permeability material, and its axial width is not less than the axial length of the tail winding end of the brushless motor. The inner diameter of the shielding ring is interference-fitted with the outer diameter of the housing.

[0012] Preferably, the folded portions are distributed at equal angles in the circumferential direction, the included angle between adjacent folded portions is 15°~45°, and the bending angle of the folded portions is 120°~160°, so that the linkage area between adjacent folded portions presents a wavy curved surface in the folded state.

[0013] Preferably, the housing is provided with an LED indicator light, which is connected to the controller and is used to emit different colors of indicator light according to the system operating status.

[0014] Preferably, the state of the LED indicator changes with temperature as follows: in The first temperature threshold, The second temperature threshold, The third temperature threshold, It is the fourth temperature threshold, and satisfies .

[0015] This invention also provides an efficiency optimization method based on motor heat loss suppression, comprising the following steps: S1: Real-time acquisition of the winding temperature of the brushless motor and the angle of the user's trigger press ; S2: Based on winding temperature Calculate the current maximum allowable output current. : in This is the rated current of the brushless motor. The first temperature threshold, The second temperature threshold, The third temperature threshold, It is the fourth temperature threshold, and satisfies ; S3: Based on the user's trigger press angle Determine the user's required current : in This refers to the dead zone angle of the trigger switch. This refers to the maximum pressing angle of the trigger switch; S4: Command to calculate final output current : S5: Final output current command The field-oriented control driver sent to the brushless motor controls the actual output torque of the motor. S6: Using a preset sampling period Repeat steps S1 to S5.

[0016] Preferably, the temperature threshold value is: , , , .

[0017] Preferably, the maximum output current mentioned in step S2 Also based on the rate of temperature rise Perform dynamic correction: in This is a correction factor for the rate of temperature rise, with a value ranging from 0.01 to 0.05. .

[0018] As a preferred option, it also includes logic to enhance the current limiting coefficient under impact conditions: When the impact pulse indicator is detected At that time, the maximum output current mentioned in step S2 will be... Multiply by the impact depreciation factor : in The value ranges from 0.7 to 0.9; Impact pulse sign The criteria for judgment are as follows: in The threshold value for the rate of change of current under impact conditions is 30~80 A / s. The threshold value for the impact current amplitude is 30~50 A.

[0019] As a preferred option, trigger-priority response logic is also included: When the user's trigger press angle is detected When decreasing, immediately set the final output current command. Reduce to the user's required current value corresponding to the new pressing angle: This logic has a higher priority than the maximum output current described in step S2. Its slow descent characteristic.

[0020] As a preferred option, a temperature drop recovery hysteresis mechanism is also included: when From higher Falling below If not immediately restored to Instead, it maintains the current traffic limit value. After a certain time, then no more than The rate of change slowly recovered to The The value ranges from 2 to 5 seconds.

[0021] As a preferred option, hardware overheat protection is also included: when When the temperature drops, the hardware-level power-off protection is triggered, cutting off the power supply to the motor driver until the temperature returns to normal. The following allows users to manually restart; The temperature threshold for hardware power failure protection must satisfy the following conditions: .

[0022] Compared with existing technologies, this invention has the following advantages: By combining a conical airflow guide umbrella with an axial fan, this invention utilizes the wind pressure generated by the motor's own rotation speed as the driving force to automatically adjust the deployment angle of the airflow guide umbrella, achieving an adaptive heat dissipation mode of "converging and focusing at low speeds, and expanding and widening at high speeds." Furthermore, it utilizes the interaction between magnetic steel sheets or magnetic powder and the leakage magnetic field at the motor end to form a non-contact magnetic spring reset mechanism, avoiding mechanical fatigue and wear. In terms of control logic, this invention fundamentally corrects the erroneous goal of existing technologies that "attempt to control heat dissipation by adjusting rotation speed," instead adopting a strategy of "setting the maximum allowable current based on temperature," directly limiting the heat source itself, achieving logical consistency and engineering feasibility. Specifically, this invention achieves smooth power reduction through graded current limiting, making the user perceive it as "the tool gradually losing power" rather than "suddenly dying," protecting the motor while maximizing task completion. Simultaneously, it introduces a temperature rise rate correction term to predictively limit current during rapid temperature increases, avoiding temperature overshoot; and it additionally derating during impact pulses to offset the decrease in heat dissipation capacity caused by speed drops. Furthermore, this invention provides real-time feedback on the tool's thermal status through five-level LED indicator lights, preventing user misjudgment; it employs trigger-priority response logic to ensure the tool responds to user commands preferentially under any condition; and it includes a temperature drop recovery hysteresis mechanism to prevent frequent oscillations of the current limit at temperature boundaries. Finally, hardware-level power-off serves as the last line of defense, preventing motor burnout and fire in the event of software current limiting failure or extreme operating conditions, achieving comprehensive safety coverage from mechanical heat dissipation and software current limiting to hardware power-off. Attached Figure Description

[0023] The present invention will be described in further detail below with reference to the accompanying drawings and preferred embodiments. However, those skilled in the art will understand that these drawings are drawn only for the purpose of explaining the preferred embodiments and therefore should not be regarded as a limitation on the scope of the present invention. In addition, unless otherwise specified, the drawings are not necessarily drawn to scale.

[0024] Figure 1 This is a cross-sectional view of the system structure of the present invention; Figure 2 This is a cross-sectional view of the present invention; Figure 3 This is a cross-sectional view of the present invention; Figure 4 This is a temperature-current mapping curve of the present invention; Figure 5 This is a flowchart of the control method of the present invention; Figure 6 This is the timing diagram for the impact condition control of the present invention; Figure 7 This is the LED indicator state logic diagram of the present invention; Figure 8 This is a comparison chart of the temperature rise rate correction effect of the present invention; In the diagram: 1. Housing; 11. Air inlet; 12. Air outlet; 2. Brushless motor; 3. Extension shaft; 4. Axial fan; 5. Rectifier blades; 6. Air guide umbrella; 61. Folding section; 7. Shielding ring. Detailed Implementation

[0025] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Those skilled in the art will appreciate that these descriptions are merely descriptive and exemplary and should not be construed as limiting the scope of protection of the present invention.

[0026] It should be noted that similar labels in the following figures indicate similar items; therefore, once an item is defined in one figure, it may not be further defined and explained in subsequent figures. Example

[0027] This embodiment mainly describes the title of a dynamic thermal equilibrium management system for lithium-ion battery wrenches and an efficiency optimization method based on motor thermal loss suppression, as follows: This embodiment provides a specific implementation method for a dynamic thermal equilibrium management system for lithium battery wrenches.

[0028] like Figure 1-3 As shown, the lithium-ion battery wrench body includes a housing 1 and a brushless motor 2 disposed within the housing 1. The housing 1 has a horizontal working part and a vertical gripping part, and the brushless motor 2 is disposed at the tail side of the working part. An air inlet 11 is provided at the tail end of the housing 1, and an air outlet 12 is provided on the side of the housing 1.

[0029] The housing 1 is equipped with a dynamic thermal equilibrium management system, including an extension shaft 3, an axial fan 4, a flow guide structure, and a shielding ring 7.

[0030] The extension shaft 3 is connected to the rotor of the brushless motor 2 and extends axially toward the air inlet 11. The axial fan 4 is fixedly mounted on the extension shaft 3, and its heat dissipation blades are located in the outer area, that is, close to the inner wall of the housing 1.

[0031] The housing 1 is provided with annular rectifier blades 5. The rectifier region of the rectifier blades 5 overlaps with the heat dissipation blades in the axial direction, and the axial width of the overlap region is 3mm to 8mm. The rectifier blades 5 rectify the rotating airflow generated by the heat dissipation blades into an axial direction and blow it into the guide umbrella 6. The number of blades in the rectifier blades 5 is 9 to 13, and the bending direction of the blades is opposite to the bending direction of the heat dissipation blades.

[0032] The flow guiding structure includes a conical flow guiding umbrella 6 and swing rods mounted on the housing 1. The diameter of the flow guiding umbrella 6 gradually decreases from the tail to the head. The flow guiding umbrella 6 has folding sections 61 arranged in a circumferential array, and the area between each two adjacent folding sections 61 forms a linkage area. The swing rods are evenly distributed in a circumferential array at the folding sections 61; in this embodiment, there are six swing rods. The radial swing range of the swing rods forms an angle of 15-30 degrees with the axial direction, which is the maximum unfolding angle of the flow guiding umbrella 6. .

[0033] A magnetic sheet or magnetic powder is provided on the front side of the linkage area, located on the periphery of the starting end of the brushless motor 2. In this embodiment, the magnetic sheet or magnetic powder is made of iron-silicon-aluminum soft magnetic powder with a particle size of 10μm~50μm. After being combined with a polymer matrix material, it is coated on the surface of the linkage area with a coating thickness of 0.3mm~0.8mm.

[0034] The shielding ring 7 is located on the outer periphery of the tail end of the brushless motor 2. The shielding ring 7 is a closed ring structure made of high magnetic permeability material (silicon steel sheet is wound and formed in this embodiment), and its axial width is 15mm, which is greater than the axial length (12mm) of the tail winding end of the brushless motor 2. The inner diameter of the shielding ring 7 is interference-fitted and fixed to the outer diameter of the housing 1.

[0035] An elastic reset element is provided between the swing rod and the housing 1. In this embodiment, the elastic reset element is a miniature torsion spring, which is located at the hinge of the swing rod.

[0036] The folding parts 61 are distributed at equal angles in the circumferential direction (the included angle between adjacent folding parts 61 is 30°), and the bending angle of the folding parts 61 is 150°, so that the linkage area between adjacent folding parts 61 presents a wavy curved surface in the folded state.

[0037] The magnetic sheet or powder interacts with the leakage magnetic field at the head end of the brushless motor 2, generating a magnetic attraction force when the guide umbrella 6 is in the retracted state. This magnetic attraction force decreases non-linearly as the air gap increases when the guide umbrella 6 unfolds, forming a non-contact magnetic spring reset mechanism. air gap The relationship satisfies: In this embodiment, , When the air gap increases from 1.0 mm to 8.0 mm, the magnetic attraction force decreases from 2.7 N to 0.3 N, a decrease of 89%.

[0038] The preload of the elastic reset element (in this embodiment, it is...) It is less than the maximum magnetic attraction force (3.0N) generated by the magnetic steel sheet or magnetic powder in the closed state of the flow guide umbrella 6, and greater than the airflow resistance (approximately 0.5N) experienced by the flow guide umbrella 6 in the fully deployed state.

[0039] The minimum air gap between the magnetic sheet or magnetic powder and the end housing of the brushless motor 2 when the guide umbrella 6 is fully retracted. The maximum air gap between the deflector umbrella 6 and the end housing of the brushless motor 2 when the umbrella is fully deployed. .

[0040] An angle sensor or potentiometer is installed at the trigger switch to detect the user's pressing angle in real time. The sampling accuracy is no less than 0.5°, and the sampling frequency is consistent with the main control cycle. An LED indicator is also provided on housing 1 to indicate the system's operating status.

[0041] This embodiment illustrates the adaptive deployment and retraction process of the guide umbrella 6 during motor operation.

[0042] When the brushless motor 2 starts, the extension shaft 3 drives the axial fan 4 to rotate, generating axial airflow. The airflow is rectified by the rectifier blades 5 and then blows onto the guide umbrella 6. Under low speed conditions, the air pressure is relatively small, and the guide umbrella 6 remains in a closed state under the combined action of the magnetic attraction between the magnet or magnetic powder and the leakage magnetic field at the beginning of the motor and the elastic reset component.

[0043] At this time, the diameter of the airflow guide umbrella 6 is smaller, the cross-sectional area of ​​the airflow channel is reduced, the airflow is compressed and accelerated, and it washes the end area of ​​the brushless motor 2 at a higher speed, thereby achieving localized enhanced heat dissipation.

[0044] As the motor speed increases, the air pressure generated by the axial fan 4 increases. When the driving force generated by the air pressure is greater than the sum of the magnetic attraction force and the elastic force of the elastic reset element, the air guide umbrella 6 unfolds outward around the swing rod under the drive of the air pressure. After the air guide umbrella 6 unfolds, the cross-sectional area of ​​the airflow channel increases, the wind resistance decreases, and at the same time, the surface area of ​​the air guide umbrella 6 increases, and the heat dissipation area expands accordingly.

[0045] As the guide umbrella 6 unfolds, the air gap between the magnetic steel sheet or magnetic powder and the outer shell at the beginning of the motor increases, and the magnetic attraction force decreases nonlinearly (inversely proportional to the square of the air gap), further reducing the unfolding resistance and forming a positive feedback unfolding process.

[0046] When the motor speed decreases, the wind pressure decreases, and the guide umbrella 6 automatically retracts under the action of magnetic attraction and elastic reset component, returning to its initial position.

[0047] During this process, the shielding ring 7, which is located on the outer periphery of the tail end of the brushless motor 2, remains fixed to continuously shield the leakage magnetic field at the tail end of the motor.

[0048] This embodiment details the mapping relationship between temperature and maximum allowable current. The temperature threshold is set as follows: , , , Rated current .

[0049] like Figure 4 As shown, the maximum allowable current Determined by the following piecewise function:

[0050] The current limiting effect in each temperature range is shown in the table below:

[0051] Example 4: Dynamic Correction of Temperature Rise Rate This embodiment illustrates the actual effect of the temperature rise rate correction term. Setting the temperature rise rate correction coefficient. .

[0052] When the temperature rises rapidly from 65℃ at a rate of 5℃ / s, the upper limit of the current before correction is 50A, and the upper limit of the current after correction is: The upper current limit was reduced from 50A to 42.5A (a 15% decrease), effectively suppressing the trend of continuous rapid temperature rise. Comparative experiments show that, as Figure 8 As shown, the peak temperature reaches 96℃ without temperature rise rate correction and 87℃ with temperature rise rate correction, effectively preventing temperature overshoot.

[0053] This embodiment illustrates the logic for enhancing the current limiting coefficient under impact conditions. It sets the impact derating coefficient. Threshold for rate of change of impact current .

[0054] like Figure 6 As shown, when the lithium-ion wrench generates an impact pulse during the tightening of the M12 bolt, the maximum permissible current during the impact duration drops from 50A to 40A (derating by 20%), effectively reducing heat generation during the impact. Due to the short impact duration (approximately 50ms), the user can hardly perceive the power drop, but the peak temperature decreases by approximately 8~12℃.

[0055] Example 6: LED indicator status feedback This embodiment illustrates the complete status logic of the LED indicator. A miniature LED indicator is provided on the housing 1, preferably positioned in a user-visible location such as the tail of the housing 1 or above the grip area. For example... Figure 7 As shown, The LED indicator logic is as follows:

[0056] Users can monitor the tool's thermal status in real time via LED indicators, preventing protective actions from being misinterpreted as tool malfunctions.

[0057] This embodiment illustrates the implementation effect of the trigger priority response logic. When the user's trigger press angle is detected... When the current decreases, the system immediately sends the final output current command. Reduce to the user's required current value corresponding to the new pressing angle: This logic has a higher priority than the maximum output current. Its slow-descent characteristic ensures that the tool decelerates immediately when the user releases the trigger, guaranteeing the tool's "obedient" response.

[0058] This embodiment illustrates the necessity of the recovery lag mechanism. It sets the recovery lag time. seconds, maximum current recovery rate .

[0059] When the temperature fluctuates around the 65℃ boundary, the current limit of the solution without recovery hysteresis oscillates frequently (47A→50A→47A), which the user perceives as fluctuating force. The solution with recovery hysteresis maintains the current limit value for 3 seconds after the temperature drops below 65℃, and then slowly recovers at a rate of 5A / s, avoiding oscillations in the current command and improving system stability.

[0060] This embodiment illustrates hardware-level power failure protection as the last line of defense. A hardware power failure protection temperature threshold is set. .

[0061] The multi-layer protection architecture consists of: the first layer is mechanical heat dissipation (wind pressure generated by rotation speed), the second layer is software current limiting (power reduction in stages from 65℃ to T to 95℃), the third layer is software shutdown (output cut off by software when T>95℃), and the fourth layer is hardware power-off (power cut off by hardware when T>105℃).

[0062] The hardware power-off mechanism works as follows: when the temperature sensor detects... When the hardware comparator outputs a high level, it triggers the self-locking shutdown of the MOSFET drive circuit, cutting off the power supply to the motor driver. This logic is entirely implemented in hardware and does not depend on the MCU software, so it remains effective even in extreme cases where the MCU crashes or the program malfunctions.

[0063] Once the temperature drops below 95°C, the hardware comparator outputs a low level, allowing the user to manually restart the tool by re-inserting the battery or pressing the reset button.

[0064] Example 10: Comprehensive Operating Condition Comparison Test This embodiment verifies the overall effectiveness of the present invention through comparative testing. The test conditions are as follows: a lithium-ion battery wrench is used to continuously tighten an M12 bolt 25 times, with each tightening time lasting approximately 2 seconds and an interval of approximately 1 second; the ambient temperature is 25°C, and the temperature thresholds are 65 / 75 / 85 / 95°C.

[0065] The comparative test results are as follows:

[0066] Test results show that although the peak temperature of the proposed solution is slightly higher than that of the PID solution, the task completion rate is much higher than that of other solutions.

[0067] In the description of this invention, it should be noted that the terms "upper," "lower," "front," "rear," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed when in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

Claims

1. A dynamic thermal equilibrium management system for a lithium-ion battery wrench, comprising a lithium-ion battery wrench body, the lithium-ion battery wrench body having a housing and a brushless motor disposed within the housing as a power source, the housing having a horizontal working part and a vertical gripping part, the brushless motor being disposed at the tail side of the working part, an air inlet being provided at the tail end of the housing and an air outlet being provided on the side of the housing, characterized in that, The housing also houses a dynamic thermal equilibrium management system, which includes: An extension shaft connects to the rotor of the brushless motor and extends to the air inlet side; An axial fan is mounted on an extension shaft, with its cooling blades located in the outer perimeter area. The housing is provided with annular rectifier blades. The rectifier area of ​​the rectifier blades overlaps with the heat dissipation blades in the axial direction. The rectifier blades rectify the airflow generated by the heat dissipation blades in the axial direction and blow it into the guide umbrella. The flow guiding structure includes a conical flow guiding umbrella and swing rods mounted on the housing. The diameter of the flow guiding umbrella gradually decreases from the tail to the head, and the umbrella has folded sections arranged in a circumferential array. The area between each pair of adjacent folded sections forms a linkage area. The swing rods are evenly distributed in a circumferential array at the folded sections, and the radial swing range of the swing rods forms an angle of 15-30 degrees with the axial direction. A magnet or magnetic powder is provided on the front side of the linkage area, located around the outer periphery of the brushless motor's head end. The magnet or magnetic powder interacts with the leakage magnetic field at the head end of the brushless motor, generating a magnetic attraction force when the flow guiding umbrella is closed. The magnetic attraction force decreases non-linearly as the air gap increases when the guide umbrella unfolds. The minimum air gap between the magnetic steel sheet or magnetic powder and the outer shell of the brushless motor head end when the guide umbrella is fully closed is 0.5 to 2.0 mm, and the maximum air gap between the guide umbrella and the outer shell of the brushless motor head end when the guide umbrella is fully unfolded is 5.0 to 10.0 mm, forming a non-contact magnetic spring reset mechanism. An elastic reset element is provided between the swing rod and the shell. The preload of the elastic reset element is less than the maximum magnetic attraction force generated by the magnetic steel sheet or magnetic powder when the guide umbrella is closed, and greater than the airflow resistance experienced by the guide umbrella when it is fully unfolded. A shielding ring is disposed on the periphery of the tail end of the brushless motor. The shielding ring is a closed ring structure made of high magnetic permeability material. Its axial width is not less than the axial length of the tail winding end of the brushless motor. The inner diameter of the shielding ring is interference-fitted with the outer diameter of the housing.

2. The dynamic thermal equilibrium management system for a lithium-ion battery wrench according to claim 1, characterized in that, The folding parts are distributed at equal angles in the circumferential direction, with the included angle between adjacent folding parts being 15 to 45 degrees, and the bending angle of the folding parts being 120 to 160 degrees, so that the linkage area between adjacent folding parts presents a wavy curved surface in the folded state; the housing is provided with an LED indicator light, which is connected to the controller and is used to emit different colored indicator lights according to the system operating status.

3. The dynamic thermal equilibrium management system for a lithium-ion battery wrench according to claim 1, characterized in that, The LED indicator light corresponds to the following five states based on the temperature range of the winding temperature: when the winding temperature is not higher than the first temperature threshold, it displays solid green; when the winding temperature is higher than the first temperature threshold but not higher than the second temperature threshold, it displays a breathing flashing green; when the winding temperature is higher than the second temperature threshold but not higher than the third temperature threshold, it displays a rapidly flashing yellow; when the winding temperature is higher than the third temperature threshold but not higher than the fourth temperature threshold, it displays a rapidly flashing red; and when the winding temperature is higher than the fourth temperature threshold, it displays solid red. The first, second, third, and fourth temperature thresholds increase sequentially.

4. An efficiency optimization method based on motor heat loss suppression, characterized in that, The dynamic thermal equilibrium management system for a lithium-ion battery wrench, as described in any one of claims 1-3, includes the following steps: S1: Real-time acquisition of the winding temperature of the brushless motor and the angle of the user's trigger press ; S2: Calculate the maximum allowable output current based on the winding temperature: When the winding temperature is not higher than the first temperature threshold, the maximum output current is equal to the rated current of the brushless motor. When the winding temperature is higher than the first temperature threshold but not higher than the second temperature threshold, the maximum output current starts from the rated current and decreases linearly with the temperature increase to 80% of the rated current. When the winding temperature is higher than the second temperature threshold but not higher than the third temperature threshold, the maximum output current starts from 80% of the rated current and decreases linearly to 50% of the rated current as the temperature increases. When the winding temperature is higher than the third temperature threshold but not higher than the fourth temperature threshold, the maximum output current starts from 50% of the rated current and decreases linearly to 20% of the rated current as the temperature increases. When the winding temperature is higher than the fourth temperature threshold, the maximum output current drops to zero; S3: Determine the user's required current based on the user's trigger pressing angle: When the pressing angle is not greater than the trigger dead zone angle, the user's required current is zero; when the pressing angle is greater than the trigger dead zone angle but not greater than the maximum pressing angle, the user's required current increases linearly with the pressing angle, increasing linearly from zero to the rated current. S4: Command to calculate final output current: That is, the smaller of the user-demanded current and the maximum output current is taken as the final output current command; S5: Send the final output current command to the field-oriented control driver of the brushless motor to control the actual output torque of the motor; S6: Repeat steps S1 to S5 with a preset sampling period.

5. The efficiency optimization method based on motor heat loss suppression according to claim 4, characterized in that, The first temperature threshold is 65 degrees Celsius, the second temperature threshold is 75 degrees Celsius, the third temperature threshold is 85 degrees Celsius, and the fourth temperature threshold is 95 degrees Celsius. The maximum output current in step S2 is also dynamically corrected according to the temperature rise rate of the winding. When the temperature rises rapidly, the maximum output current is further reduced based on the calculated value. The higher the temperature rise rate, the greater the reduction.

6. The efficiency optimization method based on motor heat loss suppression according to claim 4, characterized in that, It also includes current limiting enhancement steps under impact conditions: The current of the brushless motor is detected in real time. When the rate of change of the current exceeds the preset threshold for the rate of change of the current or the current amplitude exceeds the preset threshold for the current amplitude, it is determined to be an impact pulse state. Under the impact pulse state, the maximum output current mentioned in step S2 is multiplied by the impact derating factor, which is between 0.7 and 0.

9.

7. The efficiency optimization method based on motor heat loss suppression according to claim 4, characterized in that, It also includes the trigger priority response step: When the user's trigger pressing angle is detected to decrease, the final output current command is immediately reduced to the smaller of the user's required current and the maximum output current corresponding to the new pressing angle. This step has a higher priority than the slow reduction characteristic of the maximum output current in step S2, ensuring that the tool decelerates immediately when the user releases the trigger.

8. The efficiency optimization method based on motor heat loss suppression according to claim 4, characterized in that, It also includes the temperature drop recovery lag step: When the winding temperature drops from above the first temperature threshold to below the first temperature threshold, the maximum output current is not immediately restored to the rated current. Instead, the current current limit value is maintained for 2 to 5 seconds before being slowly restored to the rated current.

9. The efficiency optimization method based on motor heat loss suppression according to claim 4, characterized in that, It also includes hardware overheat protection steps: When the winding temperature exceeds the hardware power-off protection temperature threshold, the hardware-level power-off protection is triggered, cutting off the power supply to the motor driver. The user is allowed to manually restart the device once the winding temperature drops below the hardware power-off protection temperature threshold by 10 degrees Celsius.

10. The efficiency optimization method based on motor heat loss suppression according to claim 4, characterized in that, When the winding temperature exceeds the hardware power-off protection temperature threshold, the LED indicator switches to a solid red state until the winding temperature drops to 10 degrees Celsius below the hardware power-off protection temperature threshold, at which point it returns to a green state.

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