Power unloading protection mechanism and electric power tool

Abstract

This invention discloses a power unloading protection mechanism and an electric tool. The power unloading protection mechanism includes an active magnet assembly, a driven magnet assembly, and an adjusting component. The active magnet assembly is connected to a power input unit, and the driven magnet assembly is connected to a power output unit. The active and driven magnet assemblies are arranged opposite each other and transmit torque through magnetic coupling. The adjusting component adjusts the distance between the active and driven magnet assemblies. When the load torque of the power output unit exceeds the current magnetic coupling transmission capacity, the active and driven magnet assemblies move relative to each other, allowing the power input unit to continue operating while the power output unit stops. This achieves power unloading under overload conditions and also accommodates the adjustment of transmission capacity under different operating conditions.

Description

Technical Field

[0001] This invention relates to the field of power tools, and in particular to a power unloading protection mechanism and a power tool. Background Technology

[0002] Reciprocating saws, as a common power tool, are widely used in woodworking, metal cutting, and construction. These tools typically use a motor to output rotational power, which is then converted into the reciprocating linear motion of a saw blade via gear transmission and a mechanism, thus achieving the cutting of the workpiece. In actual use, due to the diverse types of materials processed and the significant variations in working conditions, reciprocating saws are often affected by unstable loads during operation, such as changes in material hardness, sudden changes in cutting resistance, and saw blade jamming. Therefore, to prevent damage to the power system and transmission components due to overload, incorporating overload protection structures in reciprocating saws has become a common technical measure.

[0003] In existing technologies, overload protection for reciprocating saws often employs mechanical clutch structures or friction-based slippage structures. For example, a spring-loaded steel ball clutch disengages the steel ball when the load exceeds a set value, thus cutting off power transmission; or friction between friction plates causes slippage under overload conditions to limit torque output. Additionally, torque-limiting devices using elastic elements and toothed structures also exist. These structures can provide overload protection to some extent, but their operation typically relies on rigid or frictional contact, resulting in multiple direct mechanical contact points that are prone to wear, impact, and noise issues during long-term use. Furthermore, because these structures are often designed with fixed parameters, their overload protection thresholds are often difficult to adjust flexibly according to different working conditions, potentially leading to insufficient adaptability under both light and heavy loads.

[0004] Considering the actual usage scenarios of reciprocating saws, when the saw blade jams or experiences a sudden increase in resistance during cutting, if the overload protection structure does not respond promptly or effectively cuts off power transmission, the motor and upstream transmission components are prone to bearing significant impact loads, thus affecting the overall service life of the machine. Furthermore, if there is significant mechanical impact during the operation of the protection structure, it will adversely affect the user experience. Therefore, how to incorporate a structure into the transmission chain of a reciprocating saw that can achieve power isolation during overload, re-establish the transmission relationship after the load is restored, and reduce the impact caused by mechanical contact has become a technical problem that needs to be solved in the existing technology. Summary of the Invention

[0005] The purpose of this invention is to provide a power unloading protection mechanism and power tool to solve the problems of existing overload protection structures in reciprocating saws, which mostly rely on mechanical contact or frictional contact, easily causing wear, impact, and noise, and making it difficult to achieve timely power isolation when the saw blade jams or the load changes abruptly. To address this, this invention provides an active magnet assembly and a driven magnet assembly positioned opposite each other between the power input and power output sections, and adjusts the distance between them using an adjusting component, allowing them to transmit torque through magnetic coupling. When the load torque of the power output section exceeds the current magnetic coupling transmission capacity, the active magnet assembly and the driven magnet assembly move relative to each other, causing the power input section to continue operating while the power output section stops, thus achieving power unloading under overload conditions and also accommodating the adjustment of transmission capacity under different operating conditions.

[0006] To achieve the above objectives, the present invention provides a power unloading protection mechanism, comprising an active magnet assembly, a driven magnet assembly, and an adjusting member, wherein:

[0007] The active magnet assembly is used to connect to the power input unit, and the driven magnet assembly is used to drive the power output unit.

[0008] The active magnet assembly and the driven magnet assembly are arranged opposite to each other and transmit torque through magnetic coupling.

[0009] The adjusting member is used to adjust the distance between the active magnet assembly and the driven magnet assembly. When the load torque of the power output unit exceeds the current magnetic coupling transmission capacity, the active magnet assembly and the driven magnet assembly generate relative movement, so that the power input unit continues to operate while the power output unit stops operating.

[0010] In some embodiments, the active magnet assembly and the driven magnet assembly are arranged opposite each other along an assembly axis. The driven magnet assembly is movable along the assembly axis, and the adjusting member can press against the driven magnet assembly to move it, thereby adjusting the distance between the active magnet assembly and the driven magnet assembly. With this arrangement, the movement path of the adjusting member corresponds to the movement path of the driven magnet assembly, facilitating the adjustment of the magnetic coupling transmission capability by changing the position of the driven magnet assembly.

[0011] In some embodiments, the power unloading protection mechanism further includes an elastic element disposed between the active magnet assembly and the driven magnet assembly to apply an elastic force along the assembly axis to the driven magnet assembly. By providing the elastic element, an axial force can be provided to the driven magnet assembly, which helps the driven magnet assembly maintain its corresponding assembly state after adjustment.

[0012] In some embodiments, the active magnet assembly includes an active mounting member and a first magnet, and the driven magnet assembly includes a driven mounting member and a second magnet. The first magnet is disposed on the active mounting member, and the second magnet is disposed on the driven mounting member. The active mounting member is used to connect to the power input unit and rotate with the power input unit, and the driven mounting member is used to drively connect to the power output unit. With this configuration, the active magnet assembly is used to receive rotation on the power input side, and the driven magnet assembly is used to output the magnetically coupled power to the power output unit, thereby forming a power unloading relationship between the power input unit and the power output unit.

[0013] In some embodiments, the active mounting component includes a driven gear and a first pressure plate, with the first magnet disposed between the driven gear and the first pressure plate. The driven mounting component includes a second mounting plate and a second pressure plate, with the second magnet disposed between the second mounting plate and the second pressure plate. Through this arrangement, the first magnet and the second magnet are respectively mounted on their respective mounting components, facilitating the assembly of the active magnet assembly and the driven magnet assembly, and enabling them to participate in transmission.

[0014] In some embodiments, the adjusting member is threaded into the power output section. When rotated, the adjusting member advances along the assembly axis and changes the distance between the active and driven magnet assemblies by pressing against the driven magnet assembly. Further, the adjusting member can be a nut. With the above configuration, axial advancement can be achieved through the rotation of the adjusting member, and this advancing action can be transmitted to the driven magnet assembly to adjust the distance between the active and driven magnet assemblies.

[0015] The present invention also provides an electric tool including the aforementioned power unloading protection mechanism. By providing the aforementioned power unloading protection mechanism, the electric tool can transmit power under normal operating conditions through the magnetic coupling between the active magnet assembly and the driven magnet assembly, and can unload power between the power input and power output units under overload conditions.

[0016] In some embodiments, the power tool further includes a power input unit, a power output unit, and an actuator. The driving magnet assembly is connected to the power input unit, the driven magnet assembly is drive-connected to the power output unit, and the power output unit is drive-connected to the actuator. With this arrangement, a power unloading protection mechanism is positioned between the power input unit and the power output unit, thereby isolating overload in the power tool's drivetrain.

[0017] In some embodiments, the power input unit includes a motor rotor and a transmission gear. The transmission gear is connected to the motor rotor and meshes with a driven gear in the active magnet assembly to transmit the motor output to the active magnet assembly. The power output unit is an output shaft that passes through the active magnet assembly and the driven magnet assembly. With this configuration, the power unloading protection mechanism can form a corresponding transmission relationship with the front-end transmission unit and the rear-end execution unit of the power tool, so that power unloading can be achieved through the relative movement between the active magnet assembly and the driven magnet assembly in the event of overload.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects:

[0019] The present invention provides an active magnet assembly and a driven magnet assembly arranged opposite to each other between the power input section and the power output section, and uses the magnetic coupling between the two to transmit torque. Therefore, within the normal load range, the power of the power input section can be transmitted to the power output section to meet the working requirements of the actuator.

[0020] When the load torque of the power output unit exceeds the current magnetic coupling transmission capacity, the active magnet assembly and the driven magnet assembly move relative to each other, causing the power input unit to continue operating while the power output unit stops, thereby reducing the possibility of overload torque being transmitted to the drivetrain. Since torque transmission primarily relies on magnetic coupling, this reduces wear, impact, and noise problems that are common with mechanical contact overload protection structures. Simultaneously, by adjusting the distance between the active and driven magnet assemblies using an adjusting mechanism, the magnetic coupling transmission capacity can be adjusted to meet the requirements of different operating conditions. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0022] Figure 1 This is a cross-sectional schematic diagram of the power unloading protection mechanism provided in an embodiment of the present invention;

[0023] Figure 2 This is a front view schematic diagram of the power tool provided in an embodiment of the present invention;

[0024] Figure 3 for Figure 2 An enlarged schematic diagram of part A in the middle;

[0025] Figure 4This is a cross-sectional schematic diagram of the power tool provided in an embodiment of the present invention;

[0026] Figure 5 This is an exploded view of a power tool provided in an embodiment of the present invention.

[0027] Explanation of reference numerals in the attached figures

[0028] 100. Power input unit; 1001. Motor rotor; 1002. Transmission gear; 200. Power unloading protection mechanism; 300. Power output unit; 400. Actuator; 11. Driven gear; 12. First pressure plate; 13. First magnet; 21. Second mounting plate; 22. Second pressure plate; 23. Second magnet; 3. Elastic element; 4. Adjusting element. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] In a first aspect of the invention, a power unloading protection mechanism is provided, as described above. Figure 2 , Figure 4 or Figure 5 The power unloading protection mechanism 200 can be arranged in the power transmission path of the power tool to transmit power under normal load conditions, and to create an unloading state between the power input side and the power output side when the load torque of the power output section 300 exceeds the predetermined transmission capacity.

[0032] Specifically, the power unloading protection mechanism 200 includes an active magnet assembly, a driven magnet assembly, and an adjusting member 4. The active magnet assembly is used to connect to the power input unit 100, and the driven magnet assembly is used to drively connect to the power output unit 300. The active magnet assembly and the driven magnet assembly are arranged opposite to each other and transmit torque through magnetic coupling. The adjusting member 4 is used to adjust the distance between the active magnet assembly and the driven magnet assembly.

[0033] Since the active magnet assembly is located on the power input side and the driven magnet assembly is located on the power output side, the power output from the power input unit 100 can first be transmitted to the active magnet assembly, then transmitted from the active magnet assembly to the driven magnet assembly via magnetic coupling, and finally transmitted from the driven magnet assembly to the power output unit 300. By arranging the active and driven magnet assemblies between the power input unit 100 and the power output unit 300, the mechanism can directly participate in the power transmission of the entire transmission path. Thus, in the event of overload, it can directly act on the power transmission chain, rather than only acting on the control system or a certain local component. This allows for earlier intervention in the transmission process when the power output unit 300 experiences jamming or a sudden change in resistance.

[0034] Furthermore, the active magnet assembly and the driven magnet assembly are arranged opposite each other and transmit torque through magnetic coupling. This relative arrangement allows an effective magnetic action path to be formed between the first magnet 13 and the second magnet 23. Since the torque transmission between them mainly relies on magnetic coupling, rather than on the mechanical engagement between the steel ball and the groove, or on the friction slippage between the friction plates, the number of direct mechanical contact points can be reduced during normal transmission, and the impact, wear, and noise caused by rigid collisions or frictional contact can be reduced during overload operation.

[0035] Furthermore, the adjusting component 4 is used to adjust the distance between the active magnet assembly and the driven magnet assembly. Since the active and driven magnet assemblies transmit torque through magnetic coupling, and the magnetic coupling transmission capacity is related to the relative distance between them, the adjusting component 4 can further change the transmission capacity of the power unloading protection mechanism 200 in its current state by altering the distance. In other words, the adjusting component 4 is not simply used for assembly or positioning, but rather intervenes in the spatial relationship between the active and driven magnet assemblies, thereby affecting the magnetic coupling transmission capacity. Because the magnetic coupling transmission capacity is adjustable, this mechanism has better adaptability to different cutting loads, different working materials, or different usage habits. If the transmission capacity of the protection mechanism is a fixed value, the protection action may be too delayed under light load conditions or too early under heavy load conditions. By changing the distance through the adjusting component 4, the protection action can be made closer to the actual working condition requirements.

[0036] When the load torque of the power output unit 300 exceeds the current magnetic coupling transmission capacity, the active magnet assembly and the driven magnet assembly generate relative movement, so that the power input unit 100 continues to operate while the power output unit 300 stops operating.

[0037] Under normal conditions, the magnetic coupling between the active and driven magnet assemblies is sufficient to transmit the torque output by the power input unit 100, thus the driven magnet assembly moves with the active magnet assembly. When the load torque of the power output unit 300 increases and exceeds the current magnetic coupling transmission capacity, the active magnet assembly continues to be driven by the power input unit 100, while the driven magnet assembly, due to increased load resistance, struggles to maintain synchronous movement, resulting in relative movement between the two. After this relative movement occurs, the continuous rotation of the power input unit 100 is no longer fully transmitted to the power output unit 300, causing the power input unit 100 to continue operating while the power output unit 300 stops.

[0038] In this embodiment, the active magnet assembly and the driven magnet assembly are preferably arranged opposite each other along the assembly axis. Structurally, being arranged opposite each other along the assembly axis means that they are arranged in the same axial direction during assembly. This facilitates maintaining the alignment between the active magnet assembly and the driven magnet assembly, and also makes it easier to adjust the spacing later by displacement along this axial direction.

[0039] The driven magnet assembly can move along the assembly axis, and the adjusting member 4 can press against the driven magnet assembly to drive it to move, thereby adjusting the distance between the active and driven magnet assemblies. After the adjusting member 4 applies force, the force is first transmitted to the driven magnet assembly, then the driven magnet assembly moves along the assembly axis, and then the distance between the active and driven magnet assemblies changes, ultimately changing the magnetic coupling transmission capability. Since this process unfolds along the assembly axis, the force transmission path is basically consistent with the displacement path, which can reduce the lateral additional load and also help maintain the relative alignment between the active and driven magnet assemblies. On the other hand, since it is the driven magnet assembly, not the active magnet assembly, that is being adjusted, the transmission structure on the power input side can remain relatively stable, which helps to avoid excessive influence on the arrangement of the front-stage power input section 100.

[0040] In some embodiments, the driven magnet assembly can be sleeved on the outer periphery of the power output section 300, or disposed on the power output section 300 via a guide structure, so that the driven magnet assembly can maintain a transmission relationship with the power output section 300 while moving axially relative to the power output section 300 along the assembly axis. Since the driven magnet assembly is both transmissionally connected to the power output section 300 and can move along the assembly axis, the adjusting member 4 can change the position of the driven magnet assembly without disrupting the overall transmission relationship of the power output section 300, allowing both adjustment and transmission functions to be performed in the same location.

[0041] In some implementations, refer to Figure 5The power unloading protection mechanism 200 also includes an elastic element 3, which is disposed between the active magnet assembly and the driven magnet assembly to apply an elastic force along the assembly axis to the driven magnet assembly, which helps to maintain the driven magnet assembly in the corresponding position after adjustment.

[0042] As an optional implementation, the elastic element 3 can be a spring. The spring can be sleeved on the outer periphery of the power output part 300, or it can be disposed at other positions between the active magnet assembly and the driven magnet assembly, as long as it can apply an elastic force along the assembly axis to the driven magnet assembly. In this embodiment, the elastic element 3 specifically consists of four compression springs disposed between the active magnet assembly and the driven magnet assembly, with the four compression springs evenly distributed along the circumference of the power output part 300.

[0043] In this embodiment, refer to Figure 1 and Figure 5 The active magnet assembly includes an active mounting component and four first magnets 13, and the driven magnet assembly includes a driven mounting component and four second magnets 23.

[0044] The first magnet 13 is disposed on the active mounting member, and the second magnet 23 is disposed on the driven mounting member. The active mounting member is used to connect with the power input unit 100 and rotate with the power input unit 100, and the driven mounting member is used to drive the power output unit 300.

[0045] The active mounting component bears the load and transmission function on the power input side. The first magnet 13 is attached to the active mounting component and can therefore move together with the active mounting component. The driven mounting component bears the load and transmission function on the power output side. The second magnet 23 is attached to the driven mounting component and can therefore participate in the force and transmission along with the driven mounting component.

[0046] In this embodiment, the active mounting component includes a driven gear 11 and a first pressure plate 12, with a first magnet 13 disposed between the driven gear 11 and the first pressure plate 12. The driven mounting component includes a second mounting plate 21 and a second pressure plate 22, with a second magnet 23 disposed between the second mounting plate 21 and the second pressure plate 22. Further, the driven gear 11 and the second mounting plate 21 are each provided with four circumferentially oriented magnet mounting slots to accommodate and engage the first magnet 13 and the second magnet 23.

[0047] The aforementioned driven gear 11 serves two purposes: firstly, it meshes with the preceding transmission gear 1002 as part of the driving mounting component; secondly, it acts as a supporting base for the first magnet 13. After the first pressure plate 12 engages with the driven gear 11, it clamps the first magnet 13 between them. This clamping relationship makes it easier to maintain the stability of the first magnet 13, thereby reducing the possibility of loosening or shifting during long-term rotation. Correspondingly, the second mounting plate 21 is used to connect to the power output unit 300. After the second pressure plate 22 engages with the second mounting plate 21, it clamps the second magnet 23 between them, thus ensuring a stable installation of the second magnet 23 on the driven side.

[0048] The driven gear 11 and the first pressure plate 12 are not only used to fix the first magnet 13, but also because the driven gear 11 itself can directly receive the meshing power from the preceding transmission gear 1002. Therefore, the active mounting component formed by the first pressure plate 12 and the driven gear 11 can bear the active side input transmission function while supporting the first magnet 13. The second mounting plate 21 and the second pressure plate 22 together form the driven mounting component, which facilitates the stable installation of the second magnet 23 and the establishment of a transmission relationship with the power output unit 300.

[0049] In some embodiments, the driven gear 11 and the first pressure plate 12, and the second mounting plate 21 and the second pressure plate 22, can be connected by fasteners. These fasteners can be screws, pins, rivets, or other connecting parts. By using fasteners, a reliable assembly relationship can be formed between the driven gear 11 and the first pressure plate 12, and between the second mounting plate 21 and the second pressure plate 22, thereby ensuring that the first magnet 13 and the second magnet 23 are stably clamped.

[0050] In this embodiment, the adjusting member 4 is threadedly engaged with the power output unit 300. When the adjusting member 4 rotates, it advances along the assembly axis and changes the distance between the active and driven magnet assemblies by pressing against the driven magnet assembly. Since the threaded engagement converts rotational motion into axial displacement, the adjusting member 4 can achieve axial advancement without an additional complex transmission conversion mechanism, and the adjustment process has good controllability. Because there is a corresponding relationship between the axial displacement and rotation of the threaded pair, the movement of the driven magnet assembly can be easily controlled by controlling the degree of rotation of the adjusting member 4, thereby controlling the change in the distance between the active and driven magnet assemblies.

[0051] In some embodiments, the adjusting element 4 is a nut, which can be hexagonal, cylindrical, or other shapes that facilitate operation. If a hexagonal nut is used, it is easier to adjust with the aid of tools; if a knurled cylindrical shape is used, it is easier to adjust by hand.

[0052] As an optional implementation, the adjusting member 4 can be used in conjunction with a limiting structure. The limiting structure can be located on the power output section 300 or on other components adjacent to the adjusting member 4. The limiting structure restricts the maximum advancing or retracting position of the adjusting member 4, thereby preventing excessive movement of the driven magnet assembly. This implementation further improves operational stability based on the adjusting function.

[0053] As another alternative implementation method, refer to Figure 2 and Figure 3 Adjustment position indicators can also be provided on the adjustment component 4 or adjacent components to allow the user to identify the current adjustment status. These additional structures improve ease of use but do not alter the fundamental concept of this invention: adjusting the distance between the active magnet assembly and the driven magnet assembly via the adjustment component 4.

[0054] The operation process of this embodiment will be described in detail below. Under normal operating conditions, the power input unit 100 outputs rotational power, driving the active magnet assembly to move. Since the first magnet 13 is mounted on the active mounting member, and the active mounting member is connected to the power input unit 100 and rotates with the power input unit 100, the first magnet 13 moves synchronously with the active magnet assembly. When the active magnet assembly moves, a magnetic coupling effect is formed between the first magnet 13 and the second magnet 23, thereby driving the driven magnet assembly to move synchronously. Since the driven magnet assembly is also connected to the power output unit 300, the movement of the driven magnet assembly is further transmitted to the power output unit 300, which then drives the actuator 400 to operate. Thus, power is transmitted step-by-step from the power input unit 100 through the active magnet assembly, the driven magnet assembly, and the power output unit 300 to the actuator 400.

[0055] When the actuator 400 experiences a sudden increase in external resistance, such as when the saw blade gets stuck in the workpiece kerf or when the hardness of the processed material changes abruptly, the resistance torque applied by the actuator 400 to the power output unit 300 increases, thereby increasing the load torque borne by the power output unit 300. Since the driven magnet assembly is connected to the power output unit 300, this load torque ultimately acts on the driven magnet assembly. If the load torque on the driven magnet assembly does not exceed the current magnetic coupling transmission capacity, the active magnet assembly can continue to drive the driven magnet assembly through magnetic coupling. If the load torque exceeds the current magnetic coupling transmission capacity, the active magnet assembly continues to move under the drive of the power input unit 100, while the driven magnet assembly, due to load limitations, cannot continue to maintain synchronization with the active magnet assembly, resulting in relative movement between the two. Because of this relative movement, the movement of the power input unit 100 is no longer fully transmitted to the power output unit 300, and the power output unit 300 stops operating. This achieves unloading from the power input side to the power output side.

[0056] After the overload is released, such as when the saw blade disengages from its jammed position or the cutting resistance decreases, the load torque borne by the power output unit 300 decreases. Since the load torque decreases to within the current magnetic coupling transmission capacity, an effective magnetic coupling transmission relationship can be re-established between the active magnet assembly and the driven magnet assembly.

[0057] As an optional implementation, the adjusting member 4 is an electrically operated adjusting member. The electrically operated adjusting member replaces the aforementioned adjusting member 4 which achieves axial advancement by manual rotation, so as to drive the driven magnet assembly to move along the assembly axis by electric drive, thereby adjusting the distance between the active magnet assembly and the driven magnet assembly, and further adjusting the magnetic coupling transmission capability between the two.

[0058] Specifically, the electric adjustment component includes a drive motor, a transmission unit, and an output adjustment unit. The drive motor provides the rotational power required for the adjustment action, the transmission unit transmits and converts the output of the drive motor to the output adjustment unit, and the output adjustment unit applies a force along the assembly axis to the driven magnet assembly to move the driven magnet assembly along the assembly axis.

[0059] Furthermore, the drive motor can be located outside the power unloading protection mechanism 200, or it can be located adjacent to the power output unit 300. The drive motor is connected to the transmission unit, and the transmission unit is connected to the output adjustment unit. The output adjustment unit is located on the side of the driven magnet assembly away from the active magnet assembly, or it is located at a position where an axial thrust can be applied to the driven magnet assembly.

[0060] Furthermore, the transmission unit includes, but is not limited to, any one or a combination thereof, of gear transmission pairs, worm gear transmission pairs, lead screw transmission pairs, synchronous belt transmission pairs, or reduction mechanisms.

[0061] For example, if the transmission part adopts a lead screw drive pair, after the drive motor outputs rotation, the rotational motion can be converted into linear propulsion motion along the assembly axis through the transmission relationship between the lead screw and the mating part, and then the output adjustment part transmits the propulsion motion to the driven magnet assembly.

[0062] In one embodiment, the output adjustment unit can be a pusher that cooperates with the driven magnet assembly. The pusher can be a push ring, push plate, push sleeve, or other component capable of applying an axial force to the driven magnet assembly. When the pusher pushes the driven magnet assembly along the assembly axis, the driven magnet assembly as a whole is displaced along the assembly axis, and the distance between the active magnet assembly and the driven magnet assembly changes accordingly.

[0063] As an optional implementation, the electric adjustment component can also form a guiding or mating relationship with the power output unit 300. Specifically, the power output unit 300 can be an output shaft, and the output adjustment component can be sleeved on the outer periphery of the output shaft or form a sliding fit with the output shaft, thereby moving along the assembly axis under the guidance of the output shaft. Since the output adjustment component moves along the output shaft and the driven magnet assembly is also in a corresponding assembly relationship with the output shaft, it can reduce the wobble or tilt during the adjustment process, thereby helping to maintain the relative parallel state between the active magnet assembly and the driven magnet assembly. When the relative parallel state is well maintained, the magnetic coupling effect between the two is also more stable, thus helping to make the change in transmission capacity before and after adjustment more consistent.

[0064] As an alternative implementation, the drive motor of the electric adjustment component can be any of a stepper motor, servo motor, geared motor, or micro motor. For example, if a stepper motor is used, the control unit can control the adjustment displacement according to the number of step pulses, thereby facilitating graded adjustment.

[0065] In a specific operation, when the power tool is in its initial state, the control unit controls the drive motor to rotate according to the current mode or load requirements. The drive motor drives the output adjustment unit to move along the assembly axis via the transmission unit. The output adjustment unit presses against the driven magnet assembly, causing the driven magnet assembly to move towards or away from the driving magnet assembly. As the position of the driven magnet assembly changes, the distance between the driving and driven magnet assemblies changes, and the current magnetic coupling transmission capability changes accordingly. Subsequently, during normal tool operation, the driving magnet assembly drives the driven magnet assembly to move through magnetic coupling, and drives the actuator 400 to work through the power output unit 300. When the load torque on the actuator 400 exceeds the current magnetic coupling transmission capability, the driving and driven magnet assemblies generate relative movement, causing the power input unit 100 to continue operating while the power output unit 300 stops operating.

[0066] As an optional implementation, the electric adjustment component also includes a control unit, which is electrically connected to the drive motor and is used to control the start, stop, direction, speed and stroke of the drive motor so that the output adjustment unit drives the driven magnet assembly to move along the assembly axis, thereby adjusting the distance between the active magnet assembly and the driven magnet assembly.

[0067] Specifically, the control unit includes a signal acquisition module, a status judgment module, a control output module, and a storage module. The signal acquisition module is used to acquire parameter information reflecting the current operating status of the power tool; the status judgment module is used to determine the working status of the power tool based on the acquired parameter information; the control output module is used to output control signals to the drive motor based on the judgment result; and the storage module is used to store preset thresholds, control strategies, and historical adjustment information.

[0068] Furthermore, the signal acquisition module acquires one or more of the operating parameters of the power input unit 100, the operating parameters of the power output unit 300, and the load parameters of the actuator 400. The operating parameters of the power input unit 100 may include one or more of the following: motor current, motor speed, motor temperature rise, and motor input power. The operating parameters of the power output unit 300 may include one or more of the following: output shaft speed, output shaft speed change rate, and output shaft obstruction state. The load parameters of the actuator 400 may include one or more of the following: saw blade movement resistance, cutting stage state, parameters corresponding to the type of cutting material, and operating vibration signals. After acquiring these parameters, the signal acquisition module can transmit them to the status judgment module.

[0069] As an optional implementation, the signal acquisition module includes a current detection unit, a speed detection unit, and a position detection unit. The current detection unit detects the motor's operating current; the speed detection unit detects the motor speed or output shaft speed; and the position detection unit detects the current position of the electric adjustment component, the driven magnet assembly, or the output adjustment section. When the current detection unit detects an increase in motor current, it indicates a possible increase in motor load; when the speed detection unit detects a decrease in speed or an increase in speed fluctuation, it indicates a possible change in resistance during power transmission; and after detecting the current adjustment position, the position detection unit provides the control unit with actual distance status information.

[0070] Furthermore, the status judgment module can establish a working condition identification process based on the collected parameters. This working condition identification process can include one or more of the following: start-up status identification, no-load status identification, normal cutting status identification, heavy-load status identification, jamming status identification, and recovery status identification. After receiving the parameter information, the status judgment module can first determine whether the power tool is in the start-up stage. If it is in the start-up stage, it can control the electric adjustment component to adjust the distance between the active magnet assembly and the driven magnet assembly to a first preset distance. This first preset distance corresponds to a low or medium magnetic coupling transmission capability. When the machine is first started, the actuator 400 has not yet entered a stable operating state. Using a more conservative initial transmission capability helps to reduce the possibility of the subsequent transmission components being subjected to excessive load due to instantaneous impact during startup.

[0071] After the power tool enters normal cutting mode, the status judgment module can determine the current load level based on the motor current, output shaft speed, and vibration status. If it is determined to be in normal cutting mode, the control output module controls the drive motor to adjust the driven magnet assembly to a second preset position, maintaining a second preset distance between the active and driven magnet assemblies. The second preset distance corresponds to the magnetic coupling transmission capability required under normal cutting conditions. This ensures that the power unloading protection mechanism 200 can meet the transmission requirements of the actuator 400 during normal cutting while maintaining an appropriate unloading trigger capability, thereby avoiding delayed protection action due to an excessively high protection threshold or frequent unloading during cutting due to an excessively low protection threshold.

[0072] When the status judgment module determines that the power tool has entered a heavy-load state based on a rapid increase in motor current, a rapid decrease in output shaft speed, or abnormal changes in vibration signals, the control output module can control the drive motor to move the driven magnet assembly towards the active magnet assembly, thereby reducing the distance between them. As the driven magnet assembly moves closer to the active magnet assembly, the magnetic coupling between them is enhanced, and the current magnetic coupling transmission capacity is increased, thus enabling it to adapt to temporarily higher cutting loads. For short-term heavy loads caused not by true jamming but by localized high material hardness or temporary changes in cutting depth, the continuity of operation can be maintained by improving the current magnetic coupling transmission capacity, reducing unnecessary unloading caused by short-term load fluctuations.

[0073] Furthermore, when the state judgment module determines that the actuator 400 is in a stuck state based on the motor current continuously exceeding the jamming threshold and the output shaft speed continuously falling below the speed threshold for a duration exceeding a preset time, the actuator 400 can be identified as being in a stuck state. In this state, the control output module can control the drive motor to move the driven magnet assembly away from the active magnet assembly, thereby increasing the distance between them. The reasoning is that as the distance between them increases, the current magnetic coupling transmission capability decreases, making it easier for the active and driven magnet assemblies to generate relative movement under the current load conditions. The power input unit 100 continues to operate while the power output unit 300 stops operating, thus entering the power unloading state more quickly. In this way, the control unit can not only adapt to heavy loads by increasing the transmission capability, but also promote faster unloading of the mechanism when it is truly stuck by decreasing the transmission capability. This gives the power unloading protection mechanism 200 the ability to actively intervene in the protection phase, rather than passively waiting for the load to exceed the current fixed threshold.

[0074] As an optional implementation, the state determination module adopts a hierarchical determination method. Specifically, the load state is divided into light load, medium load, heavy load, and jamming range. The control unit corresponds to different target spacings for each of these ranges. Thus, once the parameters acquired by the signal acquisition module change, the state determination module can determine which range the current load is in, and the control output module will then adjust the driven magnet assembly to the corresponding position. The spacing adjustment between the active and driven magnet assemblies is no longer limited to two states, but can form multiple transition states. Since multiple transition states correspond to multiple different magnetic coupling transmission capabilities, the working process of the power unloading protection mechanism 200 is more in line with the continuously changing load process in actual operation.

[0075] In conjunction with the foregoing embodiments, a second aspect of the present invention proposes a control method based on the aforementioned control unit, comprising an initialization step, a working condition acquisition step, a state judgment step, a spacing adjustment step, and a protection and recovery step. In the initialization step, the control unit reads preset initial position parameters from the storage module and controls the drive motor to adjust the electric adjustment component to the initial position. In the working condition acquisition step, the signal acquisition module acquires motor current, speed, position, and vibration signals in real time or periodically. In the state judgment step, the state judgment module identifies the current working condition based on the acquisition results. In the spacing adjustment step, the control output module controls the drive motor to change the spacing between the active magnet assembly and the driven magnet assembly based on the working condition identification results. In the protection and recovery step, when it is detected that the jam has been cleared or the load has returned to normal, the control unit controls the electric adjustment component to return the driven magnet assembly to a position suitable for re-establishing stable magnetic coupling transmission.

[0076] As an optional implementation, the aforementioned control method also includes a learning and correction process. Specifically, the control unit can record the motor current, output shaft speed, number of unloading triggers, recovery time, and final adjustment position corresponding to each operation in a storage module. Under subsequent identical or similar operating conditions, the control unit can recall historical records to correct the target spacing or threshold. For example, during the cutting of a certain type of material, if the control unit finds that premature unloading frequently occurs at the original preset spacing, it can move the driven magnet assembly slightly towards the active magnet assembly under subsequent identical operating conditions to improve the current magnetic coupling transmission capability; conversely, if it finds that the motor current is consistently high and the unloading action is delayed, it can appropriately increase the spacing between the two under subsequent identical operating conditions to allow for earlier unloading. Through this historical correction relationship, the control unit can gradually adapt the adjustment strategy to the actual operating conditions of the power tool.

[0077] Furthermore, the control unit can be set to manual and automatic modes. In manual mode, the user inputs adjustment commands through an external input component, and the control unit controls the drive motor to move the driven magnet assembly to the designated position according to the command. In automatic mode, the control unit automatically judges the status and adjusts the spacing based on the collected operating parameters. By setting manual and automatic modes, the control unit retains both the ability for direct user intervention and the ability to automatically adjust according to the operating status.

[0078] As an optional implementation, the control unit can also be set to a protection priority mode and a continuous operation priority mode. In protection priority mode, the control unit can use a lower unloading trigger threshold, i.e., control the driven magnet assembly to maintain a larger distance, making it easier for the active and driven magnet assemblies to generate relative movement under overload conditions. This allows the power tool to unload earlier when there are high requirements for the protection of transmission components and motors. In continuous operation priority mode, the control unit can control the driven magnet assembly to move closer to the active magnet assembly, improving the current magnetic coupling transmission capability. This allows the power tool to withstand a higher load before entering the unloading state when strong operational continuity is required.

[0079] In a further embodiment, the control unit can also identify that the power unloading protection mechanism 200 has entered the unloading state when it detects that the power output unit 300 has stopped operating while the power input unit 100 continues to rotate. At this time, the control unit can record the unloading start time and enter the unloading maintenance process. During the unloading maintenance process, the control unit can temporarily prevent the electric adjustment component from immediately approaching the active magnet assembly again to avoid prematurely resuming power transmission before the jamming is resolved. After detecting that the output shaft speed recovery condition is met, or after the user issues a restart command, the control unit controls the electric adjustment component to gradually return to the working position. The effect of this control process is to avoid repeated loading and unloading caused by the active magnet assembly and the driven magnet assembly repeatedly approaching each other before the jamming is resolved, thereby making the protection process more stable.

[0080] As an optional implementation, the control output module in the control unit adopts a step-by-step adjustment method. Specifically, when it is determined that the spacing needs to be changed, the control unit can first control the drive motor to perform a first-stage displacement and detect the changes in motor current and output shaft speed after the displacement. If the changes still do not meet the target conditions, a second-stage displacement is then executed. By using a step-by-step adjustment method, the over-adjustment problem caused by excessively large one-time adjustment can be reduced.

[0081] Furthermore, the control unit has multiple preset mapping relationships between target spacing and corresponding working parameters in its storage module. These mapping relationships can include one or more of the following: material type and target spacing; saw blade specification and target spacing; and working speed and target spacing. After identifying the current material type, saw blade specification, or working speed, the control unit can directly call upon the corresponding target spacing for adjustment. By establishing preset mapping relationships, the control process does not need to calculate the target position from scratch each time; instead, it can quickly adjust by calling upon existing relationships, thereby improving response speed.

[0082] In a third aspect of the invention, a power tool is also provided, which includes the aforementioned power unloading protection mechanism 200. The power tool also includes a power input unit 100, a power output unit 300, and an actuator 400. An active magnet assembly is connected to the power input unit 100, a driven magnet assembly is drivenly connected to the power output unit 300, and the power output unit 300 is drivenly connected to the actuator 400. This positions the power unloading protection mechanism 200 within the transmission path between the power input unit 100 and the actuator 400. Because the power unloading protection mechanism 200 is in this position, power can be directly transmitted under normal conditions, and power transmission to the actuator 400 can be directly cut off under overload conditions.

[0083] In one embodiment, the power input unit 100 includes a motor rotor 1001 and a transmission gear 1002. The transmission gear 1002 is connected to the motor rotor 1001 and meshes with a driven gear 11 in the active magnet assembly to transmit the motor output to the active magnet assembly. Here, the motor rotor 1001 outputs rotational power, and the transmission gear 1002 receives the power from the motor rotor 1001 and transmits it to the driven gear 11. Because the transmission gear 1002 meshes with the driven gear 11, the motor output can be transmitted to the active magnet assembly via the gear pair.

[0084] In this embodiment, the power output unit 300 is an output shaft that passes through the active magnet assembly and the driven magnet assembly. The output shaft extends along the assembly axis and passes through the corresponding assembly areas of the active and driven magnet assemblies, thus forming a relatively concentrated assembly structure between the active and driven magnet assemblies and the output shaft, which helps to reduce the axial and radial space occupied by the mechanism. Secondly, since the output shaft passes through the active and driven magnet assemblies, it is easier to establish a direct transmission relationship between the driven magnet assembly and the output shaft, and it is also beneficial for the driven magnet assembly to be axially adjusted along the output shaft direction. Thirdly, since the output shaft, as the power output unit 300, passes through the active and driven magnet assemblies, the adjusting member 4, the elastic member 3, and the driven magnet assembly can be arranged around the same axial direction, thereby ensuring that the force direction of each component is consistent.

[0085] In one embodiment of an electric reciprocating saw, the actuator 400 includes an eccentric wheel, a connecting rod, and a saw blade. The output shaft is connected to the eccentric wheel to drive the saw blade to reciprocate via the connecting rod. Specifically, when the output shaft rotates, it drives the eccentric wheel to rotate, which converts the rotational motion into eccentric motion. The connecting rod further converts this eccentric motion into the reciprocating linear motion of the saw blade, thereby completing the cutting operation.

[0086] When the electric reciprocating saw is in normal cutting mode, the motor rotor 1001 outputs power, which is transmitted to the driven gear 11 via the transmission gear 1002. The driven gear 11 drives the active mounting component and the first magnet 13 to move. The first magnet 13 drives the second magnet 23 and the driven mounting component to move through magnetic coupling. The driven mounting component drives the output shaft to rotate, and the output shaft drives the eccentric wheel, connecting rod, and saw blade to move, ultimately achieving cutting. Since the active magnet assembly and the driven magnet assembly are located between the gear transmission and the reciprocating actuator 400, the power passes through the power unloading protection mechanism 200 before entering the actuator 400. In this way, if the actuator 400 encounters abnormal resistance, the power unloading protection mechanism 200 can respond at the transmission position close to the actuator 400.

[0087] When the saw blade gets stuck in the workpiece kerf during cutting, or when the resistance suddenly increases while cutting into hard materials, the torque required for the eccentric wheel and connecting rod to continue driving the saw blade increases. This torque is fed back to the driven magnet assembly through the output shaft. If this feedback torque exceeds the current magnetic coupling transmission capacity, relative movement occurs between the active and driven magnet assemblies, the output shaft stops driving the eccentric wheel, and the eccentric wheel, connecting rod, and saw blade stop moving. However, the motor rotor 1001 and transmission gear 1002 can continue to operate.

[0088] It should be noted that in this specification, relational terms such as first and second are used only to distinguish one entity from several other entities, and do not necessarily require or imply any such actual relationship or order between these entities.

[0089] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the present invention.

Claims

1. A power unloading protection mechanism, characterized in that, It includes an active magnet assembly, a driven magnet assembly, and an adjustment component, wherein: The active magnet assembly is used to connect to the power input unit, and the driven magnet assembly is used to drive the power output unit. The active magnet assembly and the driven magnet assembly are arranged opposite to each other and transmit torque through magnetic coupling. The adjusting member is used to adjust the distance between the active magnet assembly and the driven magnet assembly. When the load torque of the power output unit exceeds the current magnetic coupling transmission capacity, the active magnet assembly and the driven magnet assembly generate relative movement, so that the power input unit continues to operate while the power output unit stops operating.

2. The power unloading protection mechanism according to claim 1, characterized in that, The active magnet assembly and the driven magnet assembly are arranged opposite to each other along the assembly axis; The driven magnet assembly can move along the assembly axis, and the adjusting member can press against the driven magnet assembly to drive the driven magnet assembly to move, thereby adjusting the distance between the active magnet assembly and the driven magnet assembly.

3. The power unloading protection mechanism according to claim 2, characterized in that, It also includes an elastic element disposed between the active magnet assembly and the driven magnet assembly to apply an elastic force along the assembly axis to the driven magnet assembly.

4. The power unloading protection mechanism according to any one of claims 1-3, characterized in that, The active magnet assembly includes an active mounting component and a first magnet, and the driven magnet assembly includes a driven mounting component and a second magnet; The first magnet is disposed on the active mounting member, and the second magnet is disposed on the driven mounting member. The active mounting member is used to connect with the power input unit and rotate with the power input unit, and the driven mounting member is used to drively connect with the power output unit.

5. The power unloading protection mechanism according to claim 4, characterized in that, The active mounting component includes a driven gear and a first pressure plate, wherein the first magnet is disposed between the driven gear and the first pressure plate; The driven mounting component includes a second mounting plate and a second pressure plate, with the second magnet disposed between the second mounting plate and the second pressure plate.

6. The power unloading protection mechanism according to claim 4, characterized in that, The adjusting member is used to engage with the power output part via a thread. When the adjusting member rotates, it advances along the assembly axis and changes the distance between the active magnet assembly and the driven magnet assembly by pressing against the driven magnet assembly.

7. The power unloading protection mechanism according to claim 6, characterized in that, The adjusting component is a nut.

8. A power tool, characterized in that, Includes the power unloading protection mechanism as described in any one of claims 1-7.

9. The power tool according to claim 8, characterized in that, The power tool further includes a power input unit, a power output unit, and an actuator. The active magnet assembly is connected to the power input unit, the driven magnet assembly is drivenly connected to the power output unit, and the power output unit is drivenly connected to the actuator.

10. The power tool according to claim 9, characterized in that, The power input unit includes a motor rotor and a transmission gear. The transmission gear is connected to the motor rotor and meshes with a driven gear in the active magnet assembly to transmit the motor output to the active magnet assembly. The power output section is an output shaft, which passes through the active magnet assembly and the driven magnet assembly.

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