Three-phase direct-current brushless electric motor

Abstract

The present invention relates to the technical field of electric motors, and specifically relates to a three-phase direct-current brushless electric motor, comprising: an electric motor housing, an inner shell, a rotating shaft, a rotor, a stator, a Hall sensor, and a circuit protection device, wherein the inner shell is fixedly mounted at the upper end of the electric motor housing; the rotating shaft is rotatably connected to the electric motor housing; the rotor and the stator are mounted inside the inner shell; and the Hall sensor is rotatably fitted with the rotating shaft. The circuit protection device is located above the rotor; during operation, when the rotating shaft is stuck due to a fault, or when there is an overload, the circuit protection device controls the disconnection of a circuit, thereby realizing the power-off self-locking of the electric motor by means of a load control module, thus avoiding the demagnetization of a rotor permanent magnet at a high temperature caused by heating of the electric motor, and avoiding affecting the rotation speed and normal use of the electric motor.

Description

A three-phase brushless DC motor Technical Field

[0001] The present invention relates to the technical field of motors, and in particular to a three-phase brushless DC motor. Background Art

[0002] A three-phase brushless DC motor is a motor with three-phase windings, no brushes, and a commutator. It is driven by direct current through an inverter circuit. Three-phase brushless DC motors convert electrical energy into mechanical energy through the interaction of magnetic fields. When the motor is energized, a magnetic field is generated in the stator coils. This magnetic field interacts with the magnetic field of the permanent magnets, generating a rotational torque that rotates the rotor. Sensors detect rotor position and speed and transmit signals to the electronic speed controller. Based on the sensor signals, the electronic speed controller controls the magnitude and direction of the current and voltage to adjust the motor's speed and torque.

[0003] Three-phase brushless DC motors are widely used in industry, transportation, and home appliances. In industry, they are widely used in equipment such as machine tools, printing presses, and textile machines. In transportation, they are widely used in vehicles like electric vehicles and electric motorcycles. In the home appliance sector, they are widely used in appliances such as air conditioners, washing machines, and electric fans. Three-phase brushless DC motors are efficient, reliable, and precise motors with broad application prospects.

[0004] The rotors in three-phase brushless DC motors are mostly surface-mounted permanent magnets. Radially magnetized tile-like rare earth permanent magnets are attached to the outer surface of the iron core to ensure a close fit between the permanent magnets and the rotor surface. Furthermore, the permanent magnets are made of rare earth alloys, which are relatively expensive. Permanent magnets can demagnetize at high temperatures. If the shaft becomes stuck or overloaded during motor operation, this can increase internal iron loss, generate significant heat, and cause the motor to overheat. This can damage the permanent magnet material and the motor, shortening its service life.

[0005] The three-phase brushless DC motor in the existing technology will shut down when it is overloaded and heated, and needs to be shut down and restarted again to operate normally. In actual application, the motor needs to be shut down again after shutting down due to overload, and the operation process is relatively complicated. In addition, if the shaft gets stuck during the use of the motor, the motor will heat up after a period of time, which can easily cause demagnetization and damage of the permanent magnet, thereby affecting the normal use of the motor.

[0006] In view of the above situation, in order to overcome the above technical problems, the present invention designs a three-phase brushless DC motor to solve the above technical problems. Summary of the Invention

[0007] The technical problem to be solved by the present invention is that when a three-phase brushless DC motor stops due to overload, it needs to be shut down and restarted again, and the operation process is relatively complicated. During the use of the motor, when the motor shaft becomes stuck, the motor heats up after a period of time, and the permanent magnets in the motor will be demagnetized at high temperatures, thereby affecting the motor's speed and normal use.

[0008] In order to solve the above problems, the present invention provides the following technical solutions:

[0009] The present invention provides a three-phase DC brushless motor, comprising a motor housing, an inner housing, a rotating shaft, a rotor, a stator, a Hall sensor and a circuit protection device; the inner housing is fixedly mounted on the upper end of the motor housing, specifically by a threaded connection; the rotating shaft is rotatably connected to the motor housing; the rotor is fixedly mounted on the rotating shaft, specifically by gluing, and the stator is fixedly mounted on the inner wall of the inner housing; the Hall sensor is rotatably mounted on the rotating shaft, and the Hall sensor is located below the rotor; the circuit protection device is located above the rotor, and the function of the circuit protection device is to automatically cut off the power supply when the motor's rotating shaft is stuck or the circuit is overloaded, thereby preventing the motor from overloading or getting stuck and causing high temperature heating, thereby protecting the motor.

[0010] The outer wall of the inner shell is fixedly mounted with an array of folded heat sinks, which better fit the outer wall of the inner shell, increase the heat dissipation area of ​​the inner shell, and achieve uniform heat dissipation within the inner shell, ensuring the normal operation of the motor. The lower end of the motor shell and the upper end of the inner shell are designed with threads for detachable disassembly, facilitating cleaning and replacement of the heat sinks. The ends of the motor shell are hollowed out to allow ventilation of the motor and prevent heat generated during operation from damaging the motor structure.

[0011] During the operation of a three-phase brushless DC motor, when the motor is energized, a magnetic field is generated in the stator coil. The magnetic field interacts with the magnetic field of the permanent magnet in the rotor to cause the rotor to rotate. The brushless motor needs to be dissipated and cooled at the same time. Therefore, an inner shell is provided to separate the drive structure of the motor and the heat sink. At this time, the circuit protection device is connected in series with the load control module to form a power-off self-locking protection circuit with the energized coil in the motor stator; when the motor shaft is stuck or the circuit is overloaded, the current path in the circuit protection device is disconnected. Under the action of the load control module, the power supply is automatically cut off when the motor is stuck or overloaded, thereby protecting the various structures in the motor from damage when overload generates high temperature.

[0012] The circuit protection device includes a fixed insulating sleeve, a sliding insulating sleeve, a connecting spring, a spring protection shell, a protection component, a conductive component, a fixed sliding frame and a limit plate; the fixed insulating sleeve is coaxially fixedly installed on the rotating shaft; the sliding insulating sleeve is coaxially slidably installed on the rotating shaft, and annular protrusions for fixing the conductive component are provided at both ends of the sliding insulating sleeve; a connecting spring is clamped between the fixed insulating sleeve and the sliding insulating sleeve, and a spring protection shell is installed on the outer side of the connecting spring; the outer wall of the fixed insulating sleeve is fixedly installed with a protection component, the conductive component is rotatably installed on the outer wall of the sliding insulating sleeve, the outer wall of the conductive component is fixedly installed with a fixed sliding frame, and the limit plate is fixedly installed on the rotating shaft.

[0013] The fixed insulating sleeve is fixedly connected to the rotating shaft and the outer wall of the fixed insulating sleeve is fixedly connected to a protective component, so that the protective component and the rotating shaft rotate together, so that the protective component controls the circuit on and off in the circuit protection device through the rotation speed of the rotating shaft, and at the same time insulates the rotating shaft to prevent it from affecting the magnetic field generated when the motor is energized; the annular protrusions at both ends of the sliding insulating sleeve limit the conductive component from sliding up and down in the rotating shaft with the sliding insulating sleeve; when the motor is in a stationary state, the connecting spring is at its free extension length, and the protective component is in contact with and connected to the circuit in the conductive component; after the power is turned on, the circuit is always kept connected when the motor rotates normally, and the protective component rotates with the fixed insulating sleeve and the rotating shaft, pushing the conductive component to slide downward, and the two ends of the connecting spring clamp the fixed insulating sleeve and the sliding insulating sleeve to achieve preliminary limiting of the conductive component, and the limit plate is below the conductive component to ensure that the position of the limit plate is the same as the farthest position to which the conductive component slides under the rated current of the motor, thereby further limiting the conductive component.

[0014] When the motor shaft fails and gets stuck, making it unable to rotate, the connecting spring loses its force after the shaft stops rotating, and the connecting spring returns to its free extension length, so that the fixed insulating sleeve and the sliding insulating sleeve connected at both ends of the connecting spring return to their initial positions, and the protective component and the conductive component also return to their initial states, thereby protecting the circuit in the motor and preventing the motor from overheating. In the event of a fault, the power is cut off and the power is automatically turned off through the load control module without the need to turn it off and on again, simplifying the operation process and reducing waste and accidents. When the motor circuit is overloaded, the conductive component slides downward, and the limit plate is fixedly connected under the conductive component to limit the conductive component and provide support force, so that the current path in the conductive component is disconnected, and the power is automatically turned off through the load control module, effectively avoiding the situation of motor overload and heating, and preventing the demagnetization of the permanent magnet from affecting the speed and normal use of the motor.

[0015] The spring protection shell includes an upper shell and a lower shell; the lower shell is fixedly connected to the sliding insulating sleeve, and the cross-sectional shape of the lower shell is "concave"; the upper shell is fixedly connected to the fixed insulating sleeve, and the cross-sectional shape of the upper shell is rectangular; the outer wall of the upper shell fits and slides with the "concave" inner wall of the lower shell; when the motor rotates, the spring rotates with the rotating shaft, and a spring protection shell that can slide and change its length is provided, which can effectively prevent the connection spring from deformation without affecting the operation of the circuit protection device.

[0016] The inner side of the fixed sliding frame is slidably connected to a sliding plate, the fixed sliding frame is annular, and the inner circular array of the fixed sliding frame is provided with a sliding groove for the sliding plate to slide; an "I"-shaped protrusion is provided on one side of the sliding plate, and the other side of the sliding plate is fixedly connected to the conductive component, which can fix the conductive component in the motor and limit its rotation; the sliding plate can slide up and down in the sliding groove of the fixed plate, and the upper and lower ends of the "I"-shaped protrusion limit the sliding range of the sliding plate, which not only completes the fixing effect of the conductive component but also does not affect the sliding process of the conductive component during operation of the motor.

[0017] The protection component includes a turntable, a rotating spring, a rotating block, a support spring, a support block and a copper sheet; the turntable is fixedly connected coaxially with the fixed insulating sleeve, the internal circular array of the turntable is provided with 4-8 rectangular slide grooves for the rotating block to slide, and the circular array at the bottom end of the turntable is provided with an arc-shaped groove for the support block to slide, and the arc-shaped groove is connected to the rectangular slide groove; one end of the rotating spring is clamped in the rectangular slide groove, and the other end of the rotating spring is clamped with the rotating block which slides in the rectangular slide groove according to the motor speed, and the rotating block is in the shape of a rectangular block; one end of the support spring is clamped in the arc-shaped groove, and the other end of the support spring is clamped with the support block which moves up and down according to the motor speed; the cross-section of the support block is in the shape of a right-angled trapezoid, and the hypotenuse of the right-angled trapezoid contacts the rectangular block so that when the motor is overloaded, the rotating block pushes the support block to move downward, thereby disconnecting the circuit in the conductive component to protect the motor; the copper sheet is fixedly installed under the support block.

[0018] The rectangular chute inside the turntable fits with the four sides of the rotating block, thereby restricting the rotating block so that the rotating block can only slide radially inside the turntable, preventing the rotating block from shifting when following the rotation of the turntable; the number of rectangular chute is 4-8 and the array is opened inside the turntable, which can ensure that the pushing force of the rotating block on the support block is uniform. The number of arc-shaped grooves corresponds to the number of rectangular chute, and the array is opened at the bottom end of the turntable, ensuring that the support block can slide and making the support block's thrust on the conductive component uniform.

[0019] The cross-section of the lower half of the support block is arc-shaped; the arc-shaped shape can balance the downward pressure of the bottom surface of the support block during the rotation of the motor, and also enable the support block to rotate in the conductive component, thereby enabling the protection component and the conductive component to work together to protect the motor circuit without affecting the operation of the motor; the upper half of the support block is provided with an inclined surface, and the inclination angle between the inclined surface and the vertical surface is 25°-30°, which can ensure that the rotating block can push the inclined surface part of the support block, thereby causing the support block to slide downward, preventing the rotating block from being unable to push the support block or the sliding distance of the support block being too short.

[0020] When the motor is stationary, the rotating spring and the support spring are in a freely extended state, so that the copper sheet under the support block and the conductive component form a stable current path; when the motor rotates normally after the power is turned on, the rotating block slides radially toward the edge of the turntable under the action of centrifugal force, thereby pushing the support block to slide downward in the arc-shaped groove and always keeping the circuit connected.

[0021] The conductive component includes a disc, a conductive sheet, a compression spring and a copper plate; the disc is coaxially connected to the sliding insulating sleeve, and an annular groove is provided on the upper surface of the disc; the annular groove provides space for the support block to move downward when the motor is overloaded, thereby pushing the copper plate to disconnect from the conductive sheet and disconnecting the circuit; the conductive sheet is fixedly mounted on the upper surface of the disc, and the shape of the conductive sheet is annular, and the annular conductive sheet fits the outer wall of the copper plate, and the conductive sheet is connected in series with the coil circuit in the stator; the shape of the copper plate is annular, and the inner and outer diameters of the outer wall of the copper plate are consistent with the inner and outer diameters of the annular groove. The inner and outer diameters of the groove are equal. The annular groove-shaped copper plate can slide in the annular groove under the thrust of the support block, and then the circuit in the motor is turned on and off by the contact and disconnection between the conductive sheet and the copper plate, so that the copper plate can slide in the annular rectangular slide while contacting and communicating with the conductive sheet outside the annular rectangular slide; the compression spring is clamped between the copper plate and the annular groove, the number of compression springs corresponds to the number of rotating springs and support springs, and the array of compression springs is installed at the bottom of the annular groove, which can ensure that the pressure on the copper plate remains balanced when the motor rotates.

[0022] This design of the protection component and the conductive component enables the protection component to rotate during the operation of the three-phase DC brushless motor. At this time, the rotating block is subjected to centrifugal force and slides toward the edge of the turntable in the rectangular slide groove, pushing the support block to slide downward in the arc-shaped groove. During the process, the copper sheet, copper plate and conductive sheet are always kept in contact with each other, thereby achieving normal circuit connectivity when the motor is working normally. When the motor shaft is stuck, the turntable stops rotating, and the centrifugal force on the rotating block suddenly disappears. The force of the rotating block pushing the support block also disappears. The support block returns to its initial position under the tension of the support spring, and the support The copper sheet under the block is disconnected from the copper plate, so that the current path in the circuit protection device is disconnected. Under the action of the load control module, the motor is automatically powered off, thereby protecting the various structures in the motor from high temperature damage when stuck; when the circuit is overloaded, the centrifugal force on the rotating block increases, pushing the support block to continue sliding downward in the arc-shaped groove, pushing the disc to slide down to the limit plate, and then the support block pushes the copper plate to slide downward in the annular groove, so that the contact between the copper plate and the conductive sheet is disconnected, resulting in the disconnection of the current path in the circuit protection device, thereby achieving the effect of automatically disconnecting the power supply when the circuit is overloaded.

[0023] The compression spring, rotating spring, supporting spring and connecting spring are made of the same material and have the same number of turns, and the diameters of the rotating spring and supporting spring are smaller than the diameter of the compression spring, and the diameter of the compression spring is smaller than the diameter of the connecting spring; this design makes the rebound speed of the rotating spring and the supporting spring greater than the rebound speed of the compression spring, and the rebound speed of the connecting spring is the slowest and the force is also the smallest; therefore, when the rotating shaft of the motor fails and gets stuck, and thus cannot rotate, the centrifugal force exerted on the rotating spring after the rotating shaft stops disappears, and it returns to its free extension length, so that the supporting spring and the supporting block return to their initial state. At this time, the connecting spring has not yet returned to its free extension length, and the contact between the copper sheet and the copper plate can be disconnected, thereby achieving the effect of disconnecting the current path; and when the motor is overloaded, since the force of the connecting spring and the compression spring is smaller than that of the supporting spring, the supporting spring can push the compression spring and the connecting spring to compress, thereby achieving the contact disconnection between the copper plate and the conductive sheet.

[0024] The beneficial effects of the present invention are as follows:

[0025] 1. The circuit protection device of a three-phase brushless DC motor of the present invention can disconnect the control circuit by suddenly eliminating the centrifugal force when the motor shaft fails and becomes stuck during operation. Then, the load control module is used to achieve power-off self-locking of the motor. This prevents the permanent magnets of the rotor from demagnetizing at high temperatures after the motor heats up, thereby avoiding affecting the motor's speed and normal operation.

[0026] 2. The circuit protection device of a three-phase brushless DC motor of the present invention can disconnect the control circuit by increasing centrifugal force when the motor is overloaded during operation, and then realize the power-off self-locking of the motor through the load control module, and restore it to a static state with the power turned off, thereby preventing the internal magnetic field from being affected by the motor heating, and also avoiding the complicated operation of shutting down and then restarting the power supply after shutting down after an overload. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] The above and other aspects of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0029] Figure 1 is a schematic diagram of the present invention;

[0030] FIG2 is a cross-sectional view of the present invention taken along the AA direction in FIG1 ;

[0031] FIG3 is a simplified schematic diagram of the circuit inside the motor of the present invention;

[0032] FIG4 is a schematic diagram of a fixed sliding frame of the present invention;

[0033] FIG5 is a schematic diagram of a circuit protection device according to the present invention;

[0034] FIG6 is a cross-sectional view taken along the line BB in FIG5 when the motor of the present invention is rotating normally;

[0035] FIG7 is a cross-sectional view of a portion of the circuit protection device when the motor is stationary according to the present invention;

[0036] FIG8 is a cross-sectional view of a portion of the circuit protection device when the motor is stuck in the present invention;

[0037] FIG9 is a cross-sectional view of a portion of the circuit protection device when the motor is overloaded according to the present invention.

[0038] In the figure: 1. Motor housing; 2. Inner housing; 3. Rotating shaft; 4. Rotor; 5. Stator; 6. Hall sensor; 7. Circuit protection device; 71. Fixed insulating sleeve; 72. Sliding insulating sleeve; 73. Connecting spring; 74. Spring protection shell; 75. Protection assembly; 751. Turntable; 752. Rotating spring; 753. Rotating block; 754. Support spring; 755. Support block; 756. Copper sheet; 757. Rectangular slide; 758. Arc-shaped groove; 76. Conductive assembly; 761. Disc; 762. Conductive sheet; 763. Copper sheet; 764. Compression spring; 765. Annular groove; 77. Fixed sliding frame; 771. Sliding plate; 78. Limit plate. Implementation Method

[0039] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0040] As shown in Figures 1 and 2, the present invention provides a three-phase DC brushless motor, including a motor housing 1, an inner housing 2, a rotating shaft 3, a rotor 4, a stator 5, a Hall sensor 6 and a circuit protection device 7; the inner housing 2 is fixedly mounted on the upper end of the motor housing 1, and the specific mounting method is threaded connection; the heat sink is fixedly mounted on the outer wall of the inner housing 2, and the specific mounting method is bolt connection or welding; the rotating shaft 3 is rotatably connected to the motor housing 1; the rotor 4 is fixedly mounted on the rotating shaft 3, and the specific mounting method is gluing, and the stator 5 is fixedly mounted on the inner wall of the inner housing 2, and the specific mounting method is welding; the Hall sensor 6 is rotatably mounted on the rotating shaft 3, and the Hall sensor 6 is located below the rotor 4; the circuit protection device 7 is located above the rotor 4, and the function of the circuit protection device 7 is to automatically cut off the power supply when the rotating shaft 3 of the motor is stuck or the circuit is overloaded, to prevent the motor from overloading or getting stuck and causing high temperature heating, thereby protecting the motor.

[0041] The outer wall array of the inner shell 2 is fixedly installed with folded heat sinks, which increases the heat dissipation area of ​​the inner shell 2 and achieves the effect of uniform heat dissipation of the inner shell 2. The lower end of the motor shell 1 and the upper end of the inner shell 2 are designed to be detachable by threads. When it is necessary to clean the motor and replace the heat sink, the lower end of the motor shell 1 and the upper end of the inner shell 2 can be easily disassembled by rotating the lower end of the motor shell 1 and the upper end of the inner shell 2, which is convenient for cleaning and replacement of the heat sink. The two ends of the motor shell 1 are set to be hollow to ventilate the motor and prevent the heat generated by the motor during operation from damaging the motor structure.

[0042] As shown in Figure 3, the load control module, or LCE for short, is a circuit that can determine whether a load is connected to a circuit and use this information to control the operation of other loads. When the power is on, the motor operates. Once the current path in the circuit protection device 7 is disconnected, the power automatically shuts off, and the entire circuit stops supplying power, preventing accidents and waste.

[0043] As shown in Figures 2 and 3, during the operation of the three-phase DC brushless motor, after the motor is energized, a magnetic field is generated in the coil of the stator 5. The magnetic field interacts with the magnetic field of the permanent magnet in the rotor 4 to rotate the rotor 4, and the rotation of the rotor 4 drives the rotation of the shaft 3. The circuit in the circuit protection device 7 is connected in series with the load control module, and forms a power-off self-locking protection circuit with the energized coil in the stator 5 of the motor. The Hall sensor 6 detects the position and speed of the rotor 4 and adjusts the speed and torque of the motor by controlling the magnitude and direction of the current and voltage. At the same time, the heat sink dissipates heat and cools the brushless motor. When the motor's shaft 3 is stuck or the circuit is overloaded, the current path in the circuit protection device 7 is disconnected, and the power supply is automatically cut off under the action of the load control module, protecting the various structures in the motor from damage when overload generates high temperature.

[0044] As shown in Figures 2 and 4 to 6, the circuit protection device 7 includes a fixed insulating sleeve 71, a sliding insulating sleeve 72, a connecting spring 73, a spring protection shell 74, a protection component 75, a conductive component 76, a fixed sliding frame 77 and a limit plate 78; the fixed insulating sleeve 71 is coaxially fixedly mounted on the rotating shaft 3; the sliding insulating sleeve 72 is coaxially slidably mounted on the rotating shaft 3, and annular protrusions for fixing the conductive component 76 are provided at both ends of the sliding insulating sleeve 72; a connecting spring 73 for resetting the conductive component 76 is clamped between the fixed insulating sleeve 71 and the sliding insulating sleeve 72, and a spring protection shell 74 is installed on the outer side of the connecting spring 73 to prevent the spring from rotating and deforming; the outer wall of the fixed insulating sleeve 71 is fixedly mounted with the protection component 75, the conductive component 76 is rotatably mounted on the outer wall of the sliding insulating sleeve 72, the outer wall of the conductive component 76 is fixedly mounted with a fixed sliding frame 77 for fixing the conductive component 76 on the motor, and the limit plate 78 is fixedly mounted on the rotating shaft 3.

[0045] The inner side of the fixed sliding frame 77 is slidably connected to a sliding plate 771. The fixed sliding frame 77 is annular, and the inner circular array of the fixed sliding frame 77 has a sliding groove for the sliding plate 771 to slide. One side of the sliding plate 771 is fixedly connected to the conductive component 76, and the other side of the sliding plate 771 is provided with an "I"-shaped protrusion, thereby limiting the up and down sliding of the sliding plate 771 in the sliding groove of the fixed sliding frame 77 within the fixed sliding frame 77.

[0046] When the motor is in a stationary state, the motor's rotating shaft 3 is stationary. At this time, the connecting spring 73 is in its free extension length, and the protection component 75 is in contact with the circuit in the conductive component 76; after the power is turned on, the stator 5 in the motor generates a magnetic field. Under the action of the magnetic force, the rotor 4 rotates and drives the rotating shaft 3 in the motor to rotate normally. During this process, the circuit is always kept connected. The rotation of the rotating shaft 3 drives the fixed insulating sleeve 71 and the protective component 75 to rotate. During the rotation, the protective component 75 pushes the conductive component 76 to slide downward. The sliding of the conductive component 76 drives the sliding insulating sleeve 72 and the sliding plate 771 to slide in the same direction, pulling the connecting spring 73 and extending the connecting spring 73. At the maximum rated current, the motor slides the conductive component 76 to the position of the limit plate 78, and the limit plate 78 limits the conductive component 76.

[0047] When the motor shaft 3 fails and gets stuck, making it unable to rotate, the force on the connecting spring 73 disappears after the shaft 3 stops rotating. During this process, the current path in the protection component 75 and the conductive component 76 is first disconnected, and then the power switch is automatically disconnected under the action of the load control module. Subsequently, the connecting spring 73 returns to its free extension length, so that the fixed insulating sleeve 71 and the sliding insulating sleeve 72 connected at both ends of the connecting spring 73 return to their initial positions, and the protection component 75 and the conductive component 76 also return to their initial state. The current path is reconnected and returns to the initial state, preventing the motor from overheating during a fault and reducing waste and accidents.

[0048] When the motor circuit is overloaded, the limit plate 78 limits the conductive component 76 and provides support force. Under the action of centrifugal force, the structure in the protective component 75 pushes the structure in the conductive component 76, so that the current path in the conductive component 76 is disconnected. Under the action of the load control module, the power supply is automatically turned off to prevent overload heating from affecting the use of the motor. There is no need to turn the power off and on again after the power is off, which simplifies the operation process.

[0049] As shown in Figures 5 to 9, the protection assembly 75 includes a turntable 751, a rotating spring 752, a rotating block 753, a support spring 754, a support block 755 and a copper sheet 756; the turntable 751 is fixedly connected to the fixed insulating sleeve 71 coaxially, and the inner circular array of the turntable 751 is provided with 4-8 rectangular slots 757 for the sliding of the rotating block 753, and the bottom circular array of the turntable 751 is provided with an arc-shaped groove 758; the rotating spring 75 is clamped in the rectangular slot 757. 2 end, and the other end of the rotating spring 752 is clamped with a rotating block 753 that slides in a rectangular slot 757 according to the motor speed. The rotating block 753 is in the shape of a rectangular block; one end of the support spring 754 is clamped in the arc-shaped groove 758, and the other end of the support spring 754 is clamped with a supporting block 755 that moves up and down according to the motor speed; the copper sheet 756 is fixedly installed below the supporting block 755, and the copper sheet 756 is connected in series with the load control module in the motor circuit.

[0050] The cross-section of the support block 755 is in the shape of a right-angled trapezoid, and the inclination angle between the hypotenuse of the right-angled trapezoid and the vertical plane is 25°-30°. The hypotenuse of the right-angled trapezoid contacts the rectangular block, so that when the motor is overloaded, the rotating block 753 pushes the support block 755 to move downward, thereby disconnecting the circuit in the conductive component 76 to protect the motor; the cross-section of the lower half of the support block 755 is arc-shaped, thereby balancing the pressure on the bottom surface of the support block 755 during the rotation of the motor. The arc-shaped support block 755 can rotate in the copper plate 763, thereby enabling the protection component 75 and the conductive component 76 to cooperate to protect the motor circuit without affecting the operation of the motor.

[0051] The conductive component 76 includes a disc 761, a conductive sheet 762, a compression spring 764 and a copper plate 763; the disc 761 is coaxially rotatably connected to the sliding insulating sleeve 72, and an annular groove 765 is provided on the upper surface of the disc 761; the conductive sheet 762 is annular and fixedly mounted on the upper surface of the disc 761, and the specific mounting method is bolt connection or welding, and the conductive sheet 762 is located on the outside of the annular groove 765, the inner ring diameter of the conductive sheet 762 is the same as the outer ring diameter of the annular groove 765, and the conductive sheet 762 is connected in series with the coil circuit in the stator 5; the bottom of the copper plate 763 is connected to one end of the compression spring 764, the shape of the copper plate 763 is annular, and the inner and outer ring diameters of the copper plate 763 are the same as the inner and outer ring diameters of the annular groove 765; the number of the compression springs 764 is set to 4-8, and the array of compression springs 764 is mounted at the bottom of the annular groove 765.

[0052] When the motor is in a stationary state, the rotating spring 752, the supporting spring 754 and the connecting spring 73 are in a freely extended state. At this time, the copper sheet 756 under the supporting block 755 contacts the inner side of the copper plate 763, and the outer side of the copper plate 763 contacts the conductive sheet 762 to form a stable current path; after the power is turned on, when the motor rotates normally, the rotating block 753 slides radially toward the edge of the turntable 751 under the action of centrifugal force, and the rotating block 753 slides on the inclined surface of the supporting block 755, and pushes the supporting block 755 to slide downward in the arc-shaped groove 758, and in the process, the copper sheet 756, the copper plate 763 and the conductive sheet 762 are always kept in contact with each other, so that the circuit is normally connected; in the case of a stuck fault of the motor shaft 3, the turntable 751 stops rotating, the centrifugal force on the rotating block 753 suddenly disappears, and the rotating block 753 returns to the position when it was in the stationary state under the pulling force of the rotating spring 752. When the motor is overloaded, the current in the circuit increases, the speed of the shaft 3 increases, and the centrifugal force on the rotating block 753 increases. The rotating block 753 continues to slide on the inclined surface of the support block 755. After the support block 755 is pushed by the rotating block 753, it continues to slide downward in the arc-shaped groove 758. The support block 755 pushes the disc 761 to slide downward to the limit plate 78. The support block 755 continues to push the copper plate 763 to slide downward in the annular groove. After sliding for a distance, the contact between the copper plate 763 and the conductive sheet 762 is disconnected, that is, the current path in the circuit protection device 7 is disconnected, protecting the motor from damage.

[0053] The compression spring 764, rotating spring 752, support spring 754 and connecting spring 73 are made of the same material and have the same number of turns, and the diameters of the rotating spring 752 and the support spring 754 are smaller than the diameters of the compression spring 764, and the diameter of the compression spring 764 is smaller than the diameter of the connecting spring 73; when the rotating shaft 3 of the motor fails and gets stuck, and thus cannot rotate, the centrifugal force exerted on the rotating spring 752 after the rotating shaft 3 stops rotating disappears, and the rotating spring 752 returns to its free extension length. At the same time, the support spring 754 and the support block 755 return to their initial state. At this time, the connecting spring 73 has not yet returned to its free extension length, and the contact between the copper sheet 756 and the copper plate 763 is disconnected; when the motor is overloaded, the force of the connecting spring 73 and the compression spring 764 is smaller than that of the support spring 754. At this time, the support spring 754 pushes the compression spring 764 and the connecting spring 73 to be compressed, and the copper plate 763 slides in the annular groove, and the contact between the copper plate 763 and the conductive sheet 762 is disconnected, thereby achieving the effect of disconnecting the current path after overload.

[0054] During operation of the present invention, the coil of the stator 5 is energized and generates a magnetic field. The magnetic field interacts with the magnetic field of the permanent magnet in the rotor 4 to rotate the rotor 4, and the rotation of the rotor 4 drives the rotation of the shaft 3. The circuit in the circuit protection device 7 is connected in series with the load control module, and forms a power-off self-locking protection circuit with the energized coil in the stator 5 of the motor. When the shaft 3 of the motor is stuck or the circuit is overloaded, the protection component 75 controls the contact state with the conductive component 76 through the centrifugal force caused by the rotation speed of the shaft 3, thereby controlling the current path in the circuit protection device 7 to be disconnected, and automatically cutting off the power supply under the action of the load control module, protecting the various structures in the motor from damage, and preventing waste and accidents.

[0055] Those skilled in the art will understand that the present invention is not limited to the above-described embodiments and descriptions. The above descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A three-phase brushless DC motor, comprising a motor housing (1), an inner housing (2), a rotating shaft (3), a rotor (4), a stator (5) and a Hall sensor (6), wherein the inner housing (2) is fixedly mounted on the upper end of the motor housing (1), and the rotating shaft (3) is rotatably connected to the motor housing (1); the rotor (4) and the stator (5) are fixedly mounted inside the inner housing (2) of the motor, and the Hall sensor (6) is located below the rotor (4), characterized in that: The circuit protection device (7) controls the disconnection of the circuit in the motor by increasing the centrifugal force of the rotating shaft (3) when the motor is overloaded, and controls the disconnection of the circuit in the motor by eliminating the centrifugal force of the rotating shaft (3) when the motor is stuck.

2. A three-phase brushless DC motor according to claim 1, characterized in that: The circuit protection device (7) comprises a fixed insulating sleeve (71), a sliding insulating sleeve (72), a connecting spring (73), a spring protection shell (74), a protection component (75), a conductive component (76), a fixed sliding frame (77) and a limit plate (78); the fixed insulating sleeve (71) is coaxially fixedly mounted on the rotating shaft (3); the sliding insulating sleeve (72) is coaxially slidably mounted on the rotating shaft (3), and annular protrusions for fixing the conductive component (76) are provided at both ends of the sliding insulating sleeve (72); A connecting spring (73) for resetting the conductive component (76) is clamped between the fixed insulating sleeve (71) and the sliding insulating sleeve (72), and a spring protection shell (74) is installed on the outer side of the connecting spring (73); a protection component (75) is fixedly installed on the outer wall of the fixed insulating sleeve (71), the conductive component (76) is rotatably installed on the outer wall of the sliding insulating sleeve (72), a fixed sliding frame (77) is fixedly installed on the outer wall of the conductive component (76), and the limit plate (78) is fixedly installed on the rotating shaft (3).

3. A three-phase brushless DC motor according to claim 2, characterized in that: The inner side of the fixed sliding frame (77) is slidably connected to a sliding plate (771); the fixed sliding frame (77) is annular, and the inner circular array of the fixed sliding frame (77) has a sliding groove for the sliding plate (771) to slide; an "I"-shaped protrusion is provided on one side of the sliding plate (771), and the protruding parts at both ends of the "I"-shaped protrusion limit the sliding of the conductive component (76).

4. A three-phase brushless DC motor according to claim 2, characterized in that: The protection assembly (75) comprises a rotating disk (751), a rotating spring (752), a rotating block (753), a supporting spring (754), a supporting block (755) and a copper sheet (756); the rotating disk (751) is coaxially fixedly connected to the fixed insulating sleeve (71); the inner circular array of the rotating disk (751) is provided with 4 to 8 rectangular sliding grooves (757) for the rotating block (753) to slide; the rotating block (753) is slidably installed in the rectangular sliding groove (757). 753), a rotating spring (752) is clamped between the rectangular slide groove (757) and the rotating block (753); the bottom circular array of the rotating disk (751) has an arc-shaped groove (758); one end of the supporting spring (754) is clamped in the arc-shaped groove (758), and the other end of the supporting spring (754) is clamped with a supporting block (755) that moves up and down according to the motor speed; the copper sheet (756) is fixedly installed below the supporting block (755).

5. A three-phase brushless DC motor according to claim 4, characterized in that: The cross-section of the support block (755) is in the shape of a right-angled trapezoid, and the hypotenuse of the right-angled trapezoid contacts the rotating block (753), so that when the motor is overloaded, the rotating block (753) pushes the support block (755) to move downward, thereby disconnecting the circuit in the conductive component (76) to protect the motor.

6. A three-phase brushless DC motor according to claim 2, characterized in that: The conductive component (76) comprises a disk (761), a conductive sheet (762), a copper plate (763) and a compression spring (764); the disk (761) is coaxially rotatably connected to the sliding insulating sleeve (72), and an annular groove (765) is provided on the upper surface of the disk (761); the annular groove (765) provides a space for the support block (755) to move downward when the motor is overloaded, thereby disconnecting the copper plate (763) from the conductive sheet (762) and disconnecting the circuit; the conductive sheet (762) is fixedly mounted on the upper surface of the disk (761), and the conductive sheet (762) is annular in shape; the compression spring (764) is clamped between the copper plate (763) and the annular groove (765).

7. A three-phase brushless DC motor according to claim 5, characterized in that: The cross section of the lower half of the support block (755) is arc-shaped; the arc-shaped support block (755) reduces the friction force when sliding in the copper plate (763), so that the contact between the support block (755) and the copper plate (763) is smoother when the motor rotates.

8. A three-phase brushless DC motor according to claim 6, characterized in that: The copper plate (763) is in the shape of an annular groove. The annular groove copper plate (763) can slide in the annular groove (765) under the thrust of the support block (755), thereby realizing the on-off of the circuit in the motor through the contact and disconnection between the conductive sheet (762) and the copper plate (763).

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