Driving motor with overload protection for angle grinder

Abstract

The invention relates to the technical field of motors, in particular to a driving motor with overload protection for an angle grinder. The problem that a driving motor in the angle grinder is prone to being burnt and damaged when working at high load for a long time is solved. Comprising a shell which is provided with heat dissipation holes; the rotating shaft is rotationally arranged in the shell; the spline shaft is rotationally arranged on the rotating shaft, the spline shaft and the rotating shaft are both provided with blind holes, a limiting pin is installed between the blind hole of the spline shaft and the blind hole of the rotating shaft, and when the shearing force between the rotating shaft and the spline shaft is larger than the anti-shearing force of the limiting pin, the limiting pin is arranged on the spline shaft. The limiting pin is cut off, and power transmission between the rotating shaft and the spline shaft is cut off. Through the connection of the limiting pin, the device can conveniently cut off the limiting pin when the load is too large, power transmission between the rotating shaft and the spline shaft is cut off, the device is prevented from being burnt due to long-time high-load work, and unnecessary economic losses are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and particularly to a drive motor for a angle grinder with overload protection. Background Art

[0002] An angle grinder is a handheld power tool widely used in operations such as metal cutting, grinding, and polishing. It mainly consists of a high-speed rotating grinding wheel and a powerful drive motor, and can efficiently complete various high-intensity operations.

[0003] However, during actual use, especially during cutting operations, when the operator applies too much force, the drive motor of the angle grinder needs to output a greater torque to maintain the rotation of the grinding wheel. In this case, the working current of the motor increases significantly, resulting in an increase in the motor load and a rapid rise in its temperature. Being in a high-load state for a long time will cause the temperature of the motor winding to exceed its rated working temperature range, leading to the aging and even failure of the insulating material, and ultimately causing the motor to burn out or be permanently damaged.

[0004] In addition, the high load not only affects the motor itself, but also generates additional stress on other mechanical components of the angle grinder (such as gears, bearings, etc.). These components are prone to problems such as increased wear and lubrication failure when operating under high load for a long time, thus shortening the overall service life of the equipment. Summary of the Invention

[0005] In order to overcome the problems proposed in the above background art, the present invention provides a drive motor for an angle grinder with overload protection.

[0006] The technical implementation solution of the present invention is: a drive motor for an angle grinder with overload protection, including: a housing, inside which a stator and carbon brushes are installed, and the housing is provided with heat dissipation holes; a rotating shaft, rotatably arranged in the housing through bearings, and the rotating shaft is provided with a stator and a commutator; a spline shaft, rotatably arranged on the rotating shaft, both the spline shaft and the rotating shaft are provided with blind holes, and a limit pin is installed between the blind hole of the spline shaft and the blind hole of the rotating shaft. When the shear force between the rotating shaft and the spline shaft is greater than the shear resistance of the limit pin, the limit pin is cut off and the power transmission between the rotating shaft and the spline shaft is disconnected.

[0007] Furthermore, a first magnet ring is arranged on one side of the spline shaft close to the housing, and the housing is provided with a second magnet ring attracted to the first magnet ring on the spline shaft.

[0008] Furthermore, it also includes: two fixing rings, both fixedly connected to the side wall of the housing; a sliding housing, hermetically and slidably arranged between the two fixing rings, and circumferentially distributed elastic blocks are installed between the housing and the sliding housing.

[0009] Furthermore, the housing, the two fixing rings and the sliding shell cooperate to form an annular chamber which is filled with liquid.

[0010] Furthermore, it further includes: a fixing sleeve fixedly connected to the side of the housing away from the spline shaft; a first fixing shell fixedly connected to the fixing sleeve; a rotating frame rotatably arranged in the first fixing shell, and the rotating frame is used to guide the air flow; a driving unit arranged on the fixing sleeve, and the driving unit is used to drive the rotation of the rotating frame to gradually increase from low and tend to be stable.

[0011] Furthermore, the driving unit includes: a second fixing shell fixedly connected to the fixing sleeve, and a plurality of first conduits and a plurality of second conduits are communicated between the second fixing shell and the first fixing shell, wherein the extension lines at both ends of the first conduit are perpendicular to the central axis of the rotating shaft in space, and the central axis of the second conduit is parallel to the central axis of the rotating shaft; a first impeller fixedly connected to the rotating shaft and rotatably sealed in the second fixing shell; a second impeller fixedly connected to the rotating frame and rotatably sealed in the first fixing shell.

[0012] Furthermore, heat dissipation fins are fixedly connected to the side wall of the first conduit and are circumferentially distributed.

[0013] Furthermore, it further includes: a turntable fixedly connected to the rotating shaft, the turntable is provided with circumferentially distributed cylindrical cavities, a counterweight block is slidably sealed in the cylindrical cavity of the turntable, and a tension spring is installed between the counterweight block and the turntable; a third fixing shell fixedly connected to the fixing sleeve, and the third fixing shell and the turntable cooperate to form an annular cavity, and the annular cavity is communicated with the cylindrical cavity on the turntable.

[0014] Furthermore, the third fixing shell is fixedly connected with a plurality of telescopic push rods, the number of the telescopic push rods is the same as the number of the first conduits, the chambers of the telescopic push rods are communicated with the annular cavity through pipelines, the first conduit is fixedly connected with a fixing frame, a sliding frame is slidably arranged in the fixing frame, the sliding frame is inserted into the adjacent first conduit and is slidably connected with it, and the sliding frame is fixedly connected with the telescopic ends of the adjacent telescopic push rods.

[0015] Furthermore, the fixing frame is fixedly connected with a fixing rack, the fixing rack is provided with a plurality of limiting holes, and the cross section of the limiting holes of the fixing rack gradually becomes smaller with the increase of the depth. The sliding frame is fixedly connected with an elastic telescopic column. When the telescopic end of the elastic telescopic column is located in the corresponding limiting hole on the adjacent fixing rack, the fixing rack restricts the movement of the adjacent elastic telescopic column and the adjacent sliding frame.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: Through the connection of the limit pin, it is convenient for the device to cut off the limit pin when the load is too large, disconnect the power transmission between the rotating shaft and the spline shaft, avoid the device from burning out due to long-term high-load operation, and reduce unnecessary economic losses; By rotating the rotating frame in a soft start manner, the rotating frame gradually accelerates from a low speed and finally stabilizes at a certain value. During this process, the low-speed rotation of the rotating frame facilitates the rapid increase of the temperature in the device to the specified temperature in a low-temperature environment, weakens the mechanical wear of the device, and thus indirectly extends the service life of the device; By adjusting the shielding area of the sliding frame for the adjacent first conduit at different rotation speeds, the rotation speeds of the second impeller and the rotating frame are controlled, and the overall temperature of the device is controlled, further extending the service life of the device; By utilizing the limiting relationship between the blind hole on the fixing frame and the elastic telescopic column, the sliding frame is prevented from sliding frequently, making the device work more stably, reducing mechanical wear, and extending the service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a three-dimensional structural schematic diagram of the present invention; Figure 2 is a cross-sectional view of the housing and the sliding housing of the present invention; Figure 3 is a three-dimensional structural schematic diagram of the first fixing housing and the first conduit of the present invention; Figure 4 is a cross-sectional view of the fixing sleeve and the first fixing housing of the present invention; Figure 5 is a three-dimensional structural schematic diagram of the first impeller and the second impeller of the present invention; Figure 6 is a three-dimensional structural schematic diagram of the telescopic push rod and the sliding frame of the present invention; Figure 7 is a cross-sectional view of the turntable and the third fixing housing of the present invention; Figure 8 is a cross-sectional view of the fixing frame and the elastic telescopic column of the present invention.

[0018] Names of the reference numerals in the figures: 1, housing; 2, rotating shaft; 3, spline shaft; 4, limit pin; 5, fixing ring; 6, sliding housing; 7, elastic block; 8, fixing sleeve; 9, first fixing housing; 10, rotating frame; 11, second fixing housing; 12, first conduit; 13, second conduit; 14, first impeller; 15, second impeller; 16, heat sink; 17, turntable; 18, counterweight; 19, third fixing housing; 20, telescopic push rod; 21, fixing frame; 22, sliding frame; 23, fixing frame; 24, elastic telescopic column. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] In order to enable those skilled in the art to better understand the solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] Embodiment 1: A drive motor for an angle grinder with overload protection. Refer to Figure 1 and Figure 2 As shown, it includes: a housing 1, inside which a stator and carbon brushes are installed, and the housing 1 is provided with heat dissipation holes; a rotating shaft 2, rotatably arranged in the housing 1 through bearings, and the rotating shaft 2 is provided with a stator and a commutator; a spline shaft 3, rotatably arranged on the rotating shaft 2, both the spline shaft 3 and the rotating shaft 2 are provided with blind holes, and a limit pin 4 is installed between the blind holes of the spline shaft 3 and the rotating shaft 2. When the shear force between the rotating shaft 2 and the spline shaft 3 is greater than the shear resistance of the limit pin 4, the limit pin 4 is cut off and the power transmission between the rotating shaft 2 and the spline shaft 3 is disconnected; a first magnet ring is arranged on one side of the spline shaft 3 close to the housing 1, and the housing 1 is provided with a second magnet ring attracted to the first magnet ring on the spline shaft 3.

[0021] In the above solution, through the suction force between the first magnetic ring on the spline shaft 3 and the second magnetic ring on the housing 1, it is convenient for the operator to quickly and accurately assemble the spline shaft 3 on the rotating shaft 2. At the same time, under the action of the suction force, the spline shaft 3 remains stable during operation. If the limit pin 4 breaks subsequently, the magnetic adsorption installation of the spline shaft 3 is convenient for subsequent disassembly and repair. According to the power requirement of the motor, limit pins 4 made of different shear resistance materials can be set to improve the applicability of the device. Lubricating grease is applied at the adjacent bearings of the rotating shaft 2.

[0022] Refer to Figure 1 and Figure 2 As shown, it further includes: two fixing rings 5, both fixedly connected to the side wall of the housing 1; a sliding shell 6, hermetically and slidably arranged between the two fixing rings 5, and circumferentially distributed elastic blocks 7 are installed between the housing 1 and the sliding shell 6; the housing 1, the two fixing rings 5 and the sliding shell 6 cooperate to form an annular chamber, and the annular chamber is filled with liquid.

[0023] In the above solution, an antifreeze is added to the liquid between the fixing ring 5 and the sliding shell 6. At the same time, the liquid has a high viscosity and good heat dissipation performance (such as silicone oil, mineral oil, etc.). The elastic block 7 is a high molecular polymer (such as hydrogenated nitrile rubber, polyether type polyurethane). The elastic block 7 is used to support the housing 1 to make the housing 1 centered in the sliding shell 6, and at the same time, the elastic block 7 suppresses the vibration generated by the housing 1.

[0024] Specific working principle: After this device is assembled at the specified position on the angle grinder (the angle grinder consists of a drive motor, a transmission mechanism, a cutting disc, a protective cover, a control module, and a housing, where the output shaft of the drive motor is connected to the transmission mechanism, and the transmission mechanism is connected to the cutting disc), the sliding shell 6 contacts the housing of the angle grinder, and the spline shaft 3 is connected to the transmission mechanism in the angle grinder. During the process of using the angle grinder, the rotating shaft 2 rotates and drives the cutting disc to rotate through the limit pin 4, the spline shaft 3, and the transmission mechanism. Subsequently, the operator holds the angle grinder to cut the workpiece to be processed. The elastic support of the elastic block 7 on the housing 1 can weaken the vibration generated during the operation of this device. At the same time, the liquid between the sliding shell 6 and the housing 1 absorbs and dissipates the vibration energy during the operation of this device, reducing the vibration transmitted to the external structure during the operation of this device, improving the stability and comfort of the overall system. The reduction of vibration can also effectively reduce the noise generated during the operation of this device.

[0025] When the load of the angle grinder during operation is too large, the relative shear force between the rotating shaft 2 and the spline shaft 3 increases together. When the relative shear force between the rotating shaft 2 and the spline shaft 3 is greater than the shear resistance of the limit pin 4, relative rotation occurs between the spline shaft 3 and the rotating shaft 2, and the two limit pins 4 are cut off. At this time, the rotating shaft 2 rotates idly, avoiding damage to this device due to long-term high-load operation, extending the service life of this device. Subsequently, the operator shuts down this device and repairs this device and replaces the brand-new limit pins 4.

[0026] Embodiment 2: On the basis of Embodiment 1, as shown in Figures 2-4 it also includes: a fixed sleeve 8, fixedly connected to the side of the housing 1 away from the spline shaft 3; a first fixed shell 9, fixedly connected inside the fixed sleeve 8; a rotating frame 10, rotatably arranged inside the first fixed shell 9, and the rotating frame 10 is used to guide the air flow; a driving unit, arranged on the fixed sleeve 8, and the driving unit is used to drive the rotation of the rotating frame 10 to gradually increase from low and tend to be stable.

[0027] In the above solution, four circumferentially distributed rectangular holes are provided on the side wall of the fixed sleeve 8. The rectangular holes of the fixed sleeve 8 are used for gas circulation, facilitating the flow of gas to the hand-held part for preheating, improving the comfort of the operator's hand-held. The rotating frame 10 rotates outside the rotating shaft 2, and the central axis of the rotating frame 10 coincides with the central axis of the rotating shaft 2, but the rotating frame 10 does not contact the rotating shaft 2.

[0028] As shown in Figures 2-5As shown in the figure, the drive unit includes: a second fixed housing 11 fixedly connected to the fixed sleeve 8. A plurality of first conduits 12 and a plurality of second conduits 13 are connected between the second fixed housing 11 and the first fixed housing 9. The extension lines at both ends of the first conduit 12 are both spatially perpendicular to the central axis of the rotating shaft 2, and the central axis of the second conduit 13 is parallel to the central axis of the rotating shaft 2. A first impeller 14 is fixedly connected to the rotating shaft 2 and rotates in a sealed manner within the second fixed housing 11. A second impeller 15 is fixedly connected to the rotating frame 10 and rotates in a sealed manner within the first fixed housing 9. The side wall of the first conduit 12 is fixedly connected with circumferentially distributed heat dissipation fins 16.

[0029] In the above solution, the blades on the first impeller 14 and the blades on the second impeller 15 are both inclined. The blades on the first impeller 14 are inclined counterclockwise in the horizontal plane (viewed from top to bottom). Figure 5 When viewed from top to bottom), the blades on the second impeller 15 are inclined clockwise in the horizontal plane (viewed from top to bottom), and the inclination direction of the blades on the first impeller 14 is opposite to the inclination direction of the blades on the second impeller 15. The number of both the first conduits 12 and the second conduits 13 is four (this number is the actual drawing number in the attached figure, and this number can be set accordingly according to actual needs). The first fixed housing 9, the second fixed housing 11, the first conduits 12, and the second conduits 13 all store liquid. The heat dissipation fins 16 and the first conduits 12 are both made of heat-conducting materials. The liquid in the first conduits 12 is used to absorb the heat generated by this device and assist in cooling this device. At the same time, when the rotating frame 10 works and drives air flow, when the air passes through the heat dissipation fins 16, it can effectively cool the liquid in the first conduits 12. Figure 5 When viewed from top to bottom), the inclination direction of the blades on the first impeller 14 is opposite to the inclination direction of the blades on the second impeller 15. The number of both the first conduits 12 and the second conduits 13 is four (this number is the actual drawing number in the attached figure, and this number can be set accordingly according to actual needs). The first fixed housing 9, the second fixed housing 11, the first conduits 12, and the second conduits 13 all store liquid. The heat dissipation fins 16 and the first conduits 12 are both made of heat-conducting materials. The liquid in the first conduits 12 is used to absorb the heat generated by this device and assist in cooling this device. At the same time, when the rotating frame 10 works and drives air flow, when the air passes through the heat dissipation fins 16, it can effectively cool the liquid in the first conduits 12.

[0030] Specific working principle: During the operation of this device, the rotating shaft 2 drives the first impeller 14 to rotate clockwise together (for example, when viewed from top to bottom, it rotates clockwise). The first impeller 14 pushes the liquid in the second fixed housing 11 into the first conduits 12. Subsequently, the liquid passes through the first conduits 12 and impacts the second impeller 15, causing the second impeller 15 to drive the rotating frame 10 to rotate. Then, the liquid returns to the second fixed housing 11 through the second conduits 13, forming a circulating flow of the liquid. During this process, the rotation speed of the rotating frame 10 gradually increases until the rotation speed of the rotating frame 10 stabilizes. The rotation of the rotating frame 10 drives air flow, and the air flow dissipates heat and cools this device, preventing this device from overheating, thereby indirectly extending the service life of this device. At the same time, since the initial rotation speed of the rotating frame 10 is relatively low when this device is working, the heat dissipation efficiency is low at this time. The heat generated by this device during this process preheats the entire device, facilitating this device to quickly reach the optimal temperature in a low-temperature environment, softening the lubricating grease, etc. in this device, that is, shortening the duration of mechanical wear, thereby indirectly extending the service life of this device. Figure 5 Specific working principle: During the operation of this device, the rotating shaft 2 drives the first impeller 14 to rotate clockwise together (for example, when viewed from top to bottom, it rotates clockwise). The first impeller 14 pushes the liquid in the second fixed housing 11 into the first conduits 12. Subsequently, the liquid passes through the first conduits 12 and impacts the second impeller 15, causing the second impeller 15 to drive the rotating frame 10 to rotate. Then, the liquid returns to the second fixed housing 11 through the second conduits 13, forming a circulating flow of the liquid. During this process, the rotation speed of the rotating frame 10 gradually increases until the rotation speed of the rotating frame 10 stabilizes. The rotation of the rotating frame 10 drives air flow, and the air flow dissipates heat and cools this device, preventing this device from overheating, thereby indirectly extending the service life of this device. At the same time, since the initial rotation speed of the rotating frame 10 is relatively low when this device is working, the heat dissipation efficiency is low at this time. The heat generated by this device during this process preheats the entire device, facilitating this device to quickly reach the optimal temperature in a low-temperature environment, softening the lubricating grease, etc. in this device, that is, shortening the duration of mechanical wear, thereby indirectly extending the service life of this device.

[0031] Embodiment 2: On the basis of Embodiment 1, with reference to Figures 5-7 as shown, it further includes: a turntable 17, fixedly connected to the rotating shaft 2, the turntable 17 is provided with circumferentially distributed cylindrical cavities, a counterweight block 18 is hermetically and slidably arranged in the cylindrical cavity of the turntable 17, and a tension spring is installed between the counterweight block 18 and the turntable 17; a third fixed shell 19, fixedly connected in the fixed sleeve 8, and the third fixed shell 19 and the turntable 17 cooperate to form an annular cavity, and the annular cavity communicates with the cylindrical cavity on the turntable 17; the third fixed shell 19 is fixedly connected with a plurality of telescopic push rods 20, the number of the telescopic push rods 20 is the same as the number of the first conduits 12, the chambers of the telescopic push rods 20 are communicated with the annular cavity through pipelines, the first conduit 12 is fixedly connected with a fixed frame 21, a sliding frame 22 is slidably arranged on the fixed frame 21, the sliding frame 22 is inserted into the adjacent first conduit 12 and is slidably connected thereto, and the sliding frame 22 is fixedly connected with the telescopic ends of the adjacent telescopic push rods 20.

[0032] In the above solution, there are four cylindrical cavities on the turntable 17 that are circumferentially equidistantly distributed, the counterweight block 18, the telescopic push rods 20, the fixed frame 21 and the sliding frame 22 are all four in circumferential distribution, and the cylindrical cavities, the annular cavity, the chambers of the telescopic push rods 20 and the pipelines are all filled with a liquid medium. In the initial state, the sliding frame 22 does not completely block the flow cross-section of the adjacent first conduit 12, so that the liquid medium can pass through the first conduit 12.

[0033] With reference to Figure 6 and Figure 8 as shown, the fixed frame 21 is fixedly connected with a fixed frame 23, the fixed frame 23 is provided with a plurality of limit holes, and the cross-section of the limit holes of the fixed frame 23 gradually becomes smaller as the depth increases. The sliding frame 22 is fixedly connected with an elastic telescopic column 24. When the telescopic end of the elastic telescopic column 24 is located in the corresponding limit hole on the adjacent fixed frame 23, the fixed frame 23 restricts the movement of the adjacent elastic telescopic column 24 and the adjacent sliding frame 22.

[0034] In the above solution, the fixed frame 23 is provided with four limit holes, and Figure 8 the four limit holes are evenly distributed therein, and the distance between the limit holes can be set accordingly according to actual needs. The distance between two adjacent limit holes is used to represent the moving distance of the sliding frame 22, that is, it represents that the sliding frame 22 releases the blockage of the flow cross-section of the adjacent first conduit 12. The elastic telescopic column 24 is composed of a cylindrical shell, a cylindrical rod and a spring, and the spring in the elastic telescopic column 24 is always in a compressed state.

[0035] Specific working principle: During the operation of this device, the rotation of the rotating shaft 2 drives the rotation of the turntable 17 at the same time. The rotation of the turntable 17 causes the four counterweight blocks 18 to tend to move away from each other under the action of centrifugal force. The moving tendency of the four counterweight blocks 18 exerts an extrusion force on the liquid medium in the adjacent cylindrical cavity. However, at this time, since the elastic telescopic column 24 is inserted into the limit hole on the fixed frame 23, the limit force between the limit hole on the fixed frame 23 and the elastic telescopic column 24 restricts the movement of the telescopic ends of the adjacent sliding frame 22 and the adjacent telescopic push rod 20.

[0036] As the rotational speed of the rotating shaft 2 gradually increases, when the sum of the extrusion forces of the four counterweight blocks 18 on the liquid under the action of rotational centrifugal force is greater than the sum of the limit forces between the four elastic telescopic columns 24 and the adjacent sliding frame 22, at this time, the counterweight blocks 18 squeeze the liquid medium, and the counterweight blocks 18 simultaneously stretch the connected tension springs. The liquid medium enters the chambers of the four telescopic push rods 20 through the pipeline, causing the telescopic ends of the telescopic push rods 20 to drive the adjacent sliding frame 22 and the adjacent elastic telescopic column 24 to move. Under the extrusion of the fixed frame 23, the elastic telescopic column 24 undergoes a contraction change during the movement. During the process that the elastic telescopic column 24 gradually faces the next limit hole of the adjacent fixed frame 23, the elastic telescopic column 24 recovers and contacts the limit hole on the fixed frame 23. At this time, the sliding frame 22 and the telescopic ends of the telescopic push rod 20 return to the limit state. However, since the sliding frame 22 has moved a certain distance at this time, the sliding frame 22 reduces the occlusion of the flow cross-section in the adjacent first conduit 12, that is, as the rotational speed of the rotating shaft 2 increases, the flow cross-section in the first conduit 12 gradually increases, and the impact force of the flowing liquid in the first conduit 12 on the second impeller 15 is controlled to become smaller.

[0037] When the working load of this device increases (but at this time, the shear force between the rotating shaft 2 and the spline shaft 3 is less than the shear resistance of the limit pin 4), the rotational speed of the rotating shaft 2 gradually slows down. At this time, the above reverse operation will be repeated, causing the flow cross-section in the first conduit 12 to become smaller. At this time, the impact force of the flowing liquid in the first conduit 12 on the second impeller 15 becomes larger. Appropriately increase the rotational speeds of the second impeller 15 and the rotating frame 10. The increase in the rotational speed of the rotating frame 10 makes the air flow rate increase, improving the heat dissipation effect of this device, avoiding the temperature of this device from rising excessively under the action of short-term high load (without triggering the fracture of the limit pin 4), and further extending the service life of this device.

[0038] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A drive motor for an angle grinder with overload protection, characterized in that, It includes: A housing (1) with a stator and carbon brushes installed therein, and the housing (1) is provided with heat dissipation holes; A rotating shaft (2) rotatably arranged in the housing (1) through bearings, and the rotating shaft (2) is provided with a stator and a commutator; A spline shaft (3) rotatably arranged on the rotating shaft (2). Both the spline shaft (3) and the rotating shaft (2) are provided with blind holes. A limit pin (4) is installed between the blind hole of the spline shaft (3) and the blind hole of the rotating shaft (2). When the shear force between the rotating shaft (2) and the spline shaft (3) is greater than the shear resistance of the limit pin (4), the limit pin (4) is cut off and the power transmission between the rotating shaft (2) and the spline shaft (3) is disconnected; A fixed sleeve (8) fixedly connected to one side of the housing (1) away from the spline shaft (3); A first fixed housing (9) fixedly connected in the fixed sleeve (8); A rotating frame (10) rotatably arranged in the first fixed housing (9), and the rotating frame (10) is used to guide the air flow; A driving unit arranged on the fixed sleeve (8), and the driving unit is used to drive the rotation of the rotating frame (10) to gradually increase from low and tend to be stable.

2. The drive motor for an angle grinder with overload protection according to claim 1, characterized in that, A first magnet ring is arranged on one side of the spline shaft (3) close to the housing (1), and the housing (1) is provided with a second magnet ring attracted to the first magnet ring on the spline shaft (3).

3. The drive motor for an angle grinder with overload protection according to claim 2, characterized in that, It also includes: Two fixing rings (5), both fixedly connected to the side wall of the housing (1); A sliding housing (6) hermetically and slidably arranged between the two fixing rings (5), and circumferentially distributed elastic blocks (7) are installed between the housing (1) and the sliding housing (6).

4. The drive motor for a angle grinder with overload protection according to claim 3, characterized in that, The housing (1), the two fixing rings (5) and the sliding housing (6) cooperate to form an annular chamber filled with liquid.

5. The drive motor for an angle grinder with overload protection according to claim 4, characterized in that, The driving unit includes: A second fixed housing (11) fixedly connected to the fixed sleeve (8). A plurality of first conduits (12) and a plurality of second conduits (13) are communicated between the second fixed housing (11) and the first fixed housing (9). The extension lines at both ends of the first conduit (12) are perpendicular to the central axis of the rotating shaft (2) in space, and the central axis of the second conduit (13) is parallel to the central axis of the rotating shaft (2); A first impeller (14) fixedly connected to the rotating shaft (2) and rotatably sealed in the second fixed housing (11); A second impeller (15) fixedly connected to the rotating frame (10) and rotatably sealed in the first fixed housing (9).

6. The drive motor for an angle grinder with overload protection according to claim 5, characterized in that, Heat dissipation fins (16) are fixedly connected to the side wall of the first conduit (12).

7. The drive motor for an angle grinder with overload protection according to claim 6, characterized in that, It also includes: A turntable (17) fixedly connected to the rotating shaft (2). The turntable (17) is provided with circumferentially distributed cylindrical cavities. A counterweight block (18) is hermetically and slidably arranged in the cylindrical cavity of the turntable (17), and a tension spring is installed between the counterweight block (18) and the turntable (17); The third fixed housing (19) is fixedly connected inside the fixed sleeve (8), and the third fixed housing (19) and the turntable (17) cooperate to form an annular cavity, and the annular cavity communicates with the cylindrical cavity on the turntable (17).

8. The drive motor for an angle grinder with overload protection according to claim 7, characterized in that, A plurality of telescopic push rods (20) are fixedly connected to the third fixed housing (19). The number of the telescopic push rods (20) is the same as the number of the first conduits (12). The chambers of the telescopic push rods (20) communicate with the annular cavity through pipes. A fixed frame (21) is fixedly connected to the first conduit (12). A sliding frame (22) is slidably arranged on the fixed frame (21). The sliding frame (22) is inserted into the adjacent first conduit (12) and is slidably connected thereto. The sliding frame (22) is fixedly connected to the telescopic ends of the adjacent telescopic push rods (20).

9. The drive motor for an angle grinder with overload protection according to claim 8, characterized in that, A fixed bracket (23) is fixedly connected to the fixed frame (21). The fixed bracket (23) is provided with a plurality of limiting holes. The cross-section of the limiting holes of the fixed bracket (23) gradually becomes smaller as the depth increases. An elastic telescopic column (24) is fixedly connected to the sliding frame (22). When the telescopic end of the elastic telescopic column (24) is located in the corresponding limiting hole on the adjacent fixed bracket (23), the fixed bracket (23) restricts the movement of the adjacent elastic telescopic column (24) and the adjacent sliding frame (22).

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