Electric drill motor overload protection device

Abstract

The invention discloses an electric drill motor overload protection device, and relates to the technical field of circuit overload protection, the electric drill motor overload protection device comprises an electric drill main body, the side part of the electric drill main body is provided with a driving module, the electric drill main body is internally provided with an overload assembly, the overload assembly comprises a hard through pipe and an elastic through pipe, and the hard through pipe and the elastic through pipe are internally provided with connecting wires in a penetrating manner; composite connecting pieces are assembled outside the sides, close to each other, of the two connecting rods; the whole composite connecting piece is of a double-layer structure, the inner layer is an electrified contact head used for achieving circuit conduction, the outer layer is an adsorption magnetic ring playing a role in adsorption and fixation, thermal expansion of the heat sensitive piece is a continuous process, but the action of triggering the upper inclined plate to move to disconnect the circuit is completed instantly, and therefore the heat sensitive piece is not damaged. The delayed process of temperature accumulation is converted into the instant action of mechanical triggering, so that the response of the protection device is quicker and more reliable, timely intervention can be performed when the temperature of the motor just exceeds the safety range, and the operation time of the motor at the dangerous temperature is effectively shortened.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of circuit overload protection, in particular to a drill motor overload protection device. BACKGROUND

[0002] The drill motor overload protection device is a safety protection device built into a drill, mainly used to prevent the motor from being damaged due to excessive load or locked rotor. When an abnormal rise in current (such as exceeding the rated value) or the motor temperature reaches a dangerous threshold is detected, the protection circuit will immediately cut off the power supply or trigger a speed reduction mechanism. This type of protection device is compact in structure, and balances response speed and reliability.

[0003] However, the prior art still has the following defects in specific use: In the prior art, the overload of the drill motor during use can be summarized into two cases: the first is internal motor temperature overload. As the core of energy conversion during motor operation, the internal temperature of the motor continuously accumulates due to the Joule heat generated by the current passing through the winding. When the temperature exceeds the preset threshold, temperature overload occurs. The second is external drill shaft jamming overload. As the execution end of the motor output torque, the drill shaft is blocked during drilling due to hard foreign objects or drilling jamming, etc., causing the drill shaft to run and triggering the jamming overload, which is the main form of external overload of the motor.

[0004] 1. In the prior art, as the core of energy conversion during motor operation, the stator winding generates Joule heat due to resistance when the current passes through, which is the main source of heat. When the drill is in a high-load working state for a long time, such as continuously drilling hard materials, the stator winding is continuously powered, and the generated heat will continuously accumulate. In addition, if the internal insulation material of the motor is aged, it will affect the conduction of heat, further exacerbating the accumulation of heat. When these factors jointly cause the internal temperature of the motor to exceed the preset threshold, temperature overload is triggered. Excessive temperature can seriously affect the performance of the internal insulation material of the motor, causing it to age and become brittle, and the insulation performance to decrease significantly, which may cause a short circuit between the stator windings and directly burn the motor, causing the drill to not work normally, increasing maintenance costs and replacement costs. In addition, high temperature can change the physical properties of the internal components of the motor, such as reducing the fitting accuracy of the shaft, causing jamming and abnormal noise during operation, and reducing the working efficiency and stability of the drill. In addition, continuous high temperature can also affect the circuit system of the drill, causing the control module to malfunction, posing a threat to the personal safety of the operator and the safety of the working environment.

[0005] 2. Compared with the existing technology, the drill shaft, as the execution end of the motor's output torque, is in direct contact with the workpiece during drilling operations. If it encounters hard foreign objects such as steel bars in concrete or hard particles in stone, it will instantly encounter great resistance, causing the drill shaft speed to drop sharply or even stagnate. In addition, when the drilling depth is too deep, drill chips cannot be discharged in time and accumulate in the drill hole, increasing the friction resistance between the drill shaft and the workpiece. If the drill shaft is eccentric or tilted during installation, or the drill bit is worn or blunt, the contact state between the drill shaft and the workpiece will also become abnormal, aggravating the operation obstruction. When these resistances exceed the normal output torque range of the motor, the motor will forcibly output more power to maintain operation, thereby causing the drill to stick and overload. When the drill shaft is blocked, the gears, shafts and other components in the motor transmission system will be subjected to impact forces far exceeding the design standards, which can easily cause wear on the gear tooth surfaces, bending or even breakage of the shaft, seriously affecting the service life of the electric drill and increasing maintenance costs. At the same time, if the motor continues to run overloaded in the drill stuck state, the current in the circuit will surge, which may burn electrical components such as the motor windings and control switches, and even cause electrical faults such as line short circuits and leakages, posing safety hazards such as fire and electric shock.

[0006] In view of this, the present invention proposes an electric drill motor overload protection device to remedy and improve the deficiencies of the prior art. Summary of the Invention

[0007] In order to solve the above technical problems, the present invention provides an electric drill motor overload protection device to solve the technical problems raised in the above background technology.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is: an electric drill motor overload protection device, comprising an electric drill body, a drive module installed on the side of the electric drill body, an overload component provided inside the electric drill body, and the overload component comprising a rigid through-tube and an elastic through-tube, connecting wires passing through the interiors of the rigid through-tube and the elastic through-tube, and composite connectors are assembled on the outsides of the sides where the two are close to each other; the composite connector has a double-layer structure as a whole, the inner layer is a power contact head for realizing circuit conduction, and the outer layer is an adsorption magnetic ring for adsorption and fixing, and the outer side of the composite connector is symmetrically provided with an upper inclined plate and a lower inclined plate.

[0009] The device has two independent trigger protection mechanisms: temperature overload and drill jamming overload. When the electric drill body is overloaded, the upper inclined plate moves downward and is inserted between the two composite connectors, separating the two to cut off the circuit and achieve temperature overload power-off protection. When the electric drill body is overloaded, the lower inclined plate moves upward and is inserted between the two composite connectors, separating the two to cut off the circuit and achieve drill jamming overload power-off protection.

[0010] Further, the driving module is composed of a motor, a gear box and a drill shaft, and the gear box is internally provided with a ratchet structure, and the two ends of the connecting wire are electrically connected with the power supply in the electric drill body and the motor in the driving module respectively.

[0011] Further, the overload assembly further comprises an assembly shell which is slidingly connected between the electric drill body and the driving module, and the assembly shell is internally fixedly connected with a shock-absorbing ring pad which is integrally made of rubber material.

[0012] Further, the hard tube and the elastic tube are located at the same horizontal plane, the hard tube is fixedly connected with the electric drill body, and the elastic tube is movably connected with the side wall of the motor in the driving module.

[0013] Further, the outer wall of the composite connecting piece is symmetrically provided with inclined grooves, and when the composite connecting piece is in a state of close contact, the inclined grooves form a wedge-shaped gap which is adapted to the tip positions of the upper inclined plate and the lower inclined plate.

[0014] Further, the side wall of the motor in the driving module is provided with a heat-conducting convex shaft, one end of the heat-conducting convex shaft away from the motor is sleeved with a limiting cylinder, the limiting cylinder is internally provided with a heat-sensitive sheet and an extension spring, and the extension spring is made of a memory alloy material.

[0015] Further, the heat-conducting convex shaft is integrally made of boron nitride material, one end of the heat-conducting convex shaft is fixedly connected with the extension spring, one end of the extension spring away from the heat-conducting convex shaft is fixedly connected with the heat-sensitive sheet, the other end of the heat-conducting convex shaft is in close contact with the armature winding inside the motor, the heat-sensitive sheet is integrally made of nickel-chromium alloy, and the extension end of the heat-sensitive sheet is fixedly connected with the upper inclined plate, the nickel-chromium alloy has stable expansion coefficient (the expansion amount in the range of 20-100℃ can be accurately calculated), and has high heat conduction efficiency, so that the motor heat can be directly transmitted to the upper inclined plate, the heat transmission path is shortened, and the heat dissipation loss is reduced.

[0016] Further, the bottom of the assembly shell is provided with an oval touch plate, both ends of the oval touch plate are sleeved with a coil spring, one end of the coil spring is fixedly connected with the oval touch plate, and the other end is rotatably connected with the ratchet structure in the gear box.

[0017] Further, an elastic sliding shaft is installed above the oval touch plate, the lower inclined plate is fixedly connected to one end of the elastic sliding shaft away from the oval touch plate, and in the initial state, the elastic sliding shaft is in close contact with the short-axis convex surface of the oval touch plate.

[0018] Further, an arc-extinguishing cover is installed outside the composite connecting piece, when the inner layer power contact head of the composite connecting piece is separated, the arc-extinguishing cover can quickly extinguish the electric arc to avoid contact burning.

[0019] Compared with the prior art, the beneficial effects of the present application are: (1) the device adopts a splicing mode design at the internal circuit connection position of the electric drill main body, so that the connecting wire between the power supply and the motor is in movable connection, and through the cooperation between the heat-conducting convex shaft and the heat-sensitive sheet, the heat at the main heating point of the motor, i.e. the armature winding, can be quickly transmitted to the heat-sensitive sheet, thereby triggering the downward displacement of the upper inclined plate to disconnect the circuit, and the nickel-chromium alloy heat-sensitive sheet has good thermal expansion performance and can rapidly deform when the temperature rises. This structure design makes the protection device more sensitive to temperature changes, and compared with the traditional temperature sensing method, the device can more timely sense the abnormal temperature of the motor and trigger the protection mechanism in advance, effectively avoiding damage to the motor due to long-time high-temperature operation and prolonging the service life of the motor. At the same time, the splicing mode of the circuit design is convenient for installation and maintenance.

[0020] The innovation of the triggering mode of the device is that the delay process is converted into a triggering program. The traditional temperature overload protection device usually relies on the accumulation of temperature to reach a certain threshold value before triggering the protection action, which has obvious delay. In the present device, the thermal expansion of the heat-sensitive sheet is a continuous process, but the action of triggering the movement of the upper inclined plate to disconnect the circuit is completed instantaneously. This conversion of the delay process of temperature accumulation into the instantaneous action of mechanical triggering makes the response of the protection device more rapid and reliable, and can intervene in time when the temperature of the motor just exceeds the safe range, effectively shortening the running time of the motor at the dangerous temperature.

[0021] (2) More importantly, the device symmetrically introduces a lower inclined plate vertically below the same connection position, uses the sudden increase in output torque of the gear box when the drill is stuck to drive the elliptical touch plate to rotate, thereby triggering the upward displacement of the lower inclined plate to disconnect the circuit, which can quickly respond in the moment when the drill is stuck and cut off the power supply in time to avoid the continuous operation of the motor in the overload state, maximize the reduction of damage to the transmission components due to overload, prolong the service life of the electric drill, and effectively reduce the risk of safety accidents caused by out-of-control drill sticking, protect the personal safety of the operator, and make the electric drill more reliable to use in complex working environments.

[0022] This trigger mode does not need to design an independent circuit, and the same structure realizes double protection by different trigger modes. On the basis of the original temperature overload protection structure, only by symmetrically introducing the lower inclined plate below the connection position, with the help of different trigger mechanisms, i.e. the upper inclined plate acts when the temperature is overloaded, and the lower inclined plate acts when the drill is overloaded, the same set of composite connectors and circuit connection structures realize the double protection function. Not only does it simplify the internal structure of the device, reduce production and maintenance costs, but also reduces space occupation, which is conducive to the lightweight design of handheld drills. At the same time, the stability and reliability of the same structure are higher, which can reduce the hidden troubles caused by multiple circuit systems and make the implementation of protection function more efficient and stable.

[0023] (3) In the actual trigger process, the hard pipe provides a stable support basis for the connecting wire, ensuring that one end of the line connection will not be displaced due to external force. The elastic pipe can contract to a certain extent under the extrusion of the inclined plate. This contraction property can buffer the impact force generated when the inclined plate is extruded, avoiding the connecting wire between the hard pipe and the elastic pipe being pulled and worn due to excessive instantaneous force. In addition, the contraction of the elastic pipe can ensure that the line is disconnected more completely during the separation process, avoiding the state of poor contact or half-disconnection, and ensuring the reliability of the overload protection.

[0024] When the inclined plate resets, the hard pipe ensures that the internal connecting wire does not move, providing a stable reference for the reset of the elastic pipe. The elastic pipe relies on its own elasticity to reset and reconnect the line. This reset method relying on its own elasticity can quickly restore the normal working state of the drill after the overload problem is solved, reducing the time loss caused by downtime. Moreover, the elastic reset process is relatively gentle and will not cause secondary damage to the line and connector, further ensuring the long-term stable operation of the device. (4) The wedge formed by the inclined groove precisely fits the tip of the inclined plate, allowing the upper inclined plate or the lower inclined plate to smoothly embed when triggered. With the guidance and force characteristics of the inclined surface, the composite connector quickly separates, thereby quickly disconnecting the circuit. This structure avoids misalignment or jamming when the inclined plate is triggered, ensuring the smoothness of the trigger action. It can also efficiently complete the power-off protection when both types of overload occur. Moreover, the adaptive shape design reduces unnecessary wear between components, helping to maintain the device's long-term stable working state and improving the reliability of the overall protection mechanism.

[0025] Wherein, the device is installed in the electric drill shell by the damping ring pad, which can effectively block the vibration generated by the motor to the line connection position and the inclined plane, and reduce the false trigger caused by vibration interference from the source. The damping ring pad itself can absorb the vibration energy through elastic buffer, so that the overload assembly is in a relatively stable working environment, ensuring that the inclined plate will be triggered only when the temperature overload or the stuck drill overload occurs. It not only ensures the sensitivity of the protection device, but also greatly improves the working reliability, avoids the interruption of work and the decrease of efficiency caused by false triggering.

[0026] Wherein, the arc extinguishing cover installed outside the composite connecting piece can quickly extinguish the electric arc generated when the power contact head is separated, which can effectively avoid the ablation of the contact head caused by high temperature, maintain the integrity and conductivity of the contact surface, ensure the stable work of the composite connecting piece after multiple on-off, reduce the maintenance and replacement frequency caused by contact damage, reduce the use cost, and prevent the circuit interference or spark hidden danger caused by continuous discharge after arc extinguishing, improve the safety of the electric drill during use, and make the operation of the entire overload protection device more reliable. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a front view of the structure of the application; Figure 2 It is a three-dimensional structure diagram of the electric drill main body inside; Figure 3 It is a three-dimensional structure diagram of the assembly shell inside; Figure 4 It is a three-dimensional structure diagram of the arc extinguishing cover inside; Figure 5 It is a three-dimensional structure diagram of the upper inclined plate and the lower inclined plate position relationship; Figure 6 It is a three-dimensional structure diagram of the wedge slot; Figure 7 It is a three-dimensional structure diagram of the composite connecting piece;

[0028] Figure 8 It is a three-dimensional structure diagram of the upper inclined plate after triggering; Figure 9 It is a three-dimensional structure diagram of the upper inclined plate and the composite connecting piece between the plane state structure; Figure 10 It is a three-dimensional structure diagram of the limit cylinder inside; Figure 11 It is a three-dimensional structure diagram of the lower inclined plate after triggering; Figure 12 It is a three-dimensional structure diagram of the lower inclined plate and the composite connecting piece between the plane state structure; Figure 13The schematic view of the elliptical touch plate trigger structure of the present application.

[0029] Reference numerals in the drawings are: 1, electric drill main body; 11, drive module; 12, connecting wire; 2, overload assembly; 21, assembly shell; 22, shock-absorbing ring pad; 23, rigid through pipe; 24, elastic through pipe; 25, composite connecting piece; 26, inclined surface groove; 27, heat-conducting convex shaft; 28, limiting cylinder; 29, heat-sensitive sheet; 210, upper inclined plate; 211, elliptical touch plate; 212, coil spring; 213, elastic sliding shaft; 214, lower inclined plate; 215, arc-extinguishing cover. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application; It should be noted that the structure and working principle of the electric drill main body 1, the drive module 11, the connecting wire 12 and the like belong to the prior art, and will not be described here.

[0031] Embodiment 1: Please refer to Figure 1 - Figure 11 As shown in the figure, an electric drill motor overload protection device, comprising an electric drill main body 1, a drive module 11 is installed on the side of the electric drill main body 1, an overload assembly 2 is arranged inside the electric drill main body 1, the overload assembly 2 comprises a rigid through pipe 23 and an elastic through pipe 24, the connecting wire 12 is arranged inside the rigid through pipe 23 and the elastic through pipe 24, and the composite connecting piece 25 is arranged on the side of the two pipes close to each other. When the electric drill main body 1 is overloaded, the upper inclined plate 210 is displaced downward and inserted between the two composite connecting pieces 25, so that the two composite connecting pieces 25 are separated to cut off the circuit, realizing temperature overload power-off protection.

[0032] Please refer to Figure 1 - Figure 11As shown, the drive module 11 is composed of a motor, a gear box and a drill shaft combination, and the gear box is internally installed with a ratchet structure, the two ends of the connecting wire 12 are respectively in electrical connection with the power supply in the electric drill body 1 and the motor in the drive module 11, the overload assembly 2 further comprises an assembly housing 21 which is slidingly connected between the electric drill body 1 and the drive module 11, the inside of the assembly housing 21 is fixedly connected with a shock ring pad 22 which is integrally composed of rubber material, a rigid pipe 23 and an elastic pipe 24 are in the same horizontal plane, the rigid pipe 23 is fixedly connected with the electric drill body 1, the elastic pipe 24 is movably connected with the side wall of the motor in the drive module 11, the outer wall of the composite connecting piece 25 is symmetrically provided with inclined grooves 26, when the composite connecting piece 25 is kept in the state of adhesion, the inclined grooves 26 form a wedge-shaped gap which is adapted to the tip position of the upper inclined plate 210 and the lower inclined plate 214, the side wall of the motor in the drive module 11 is installed with a heat-conducting convex shaft 27, the end of the heat-conducting convex shaft 27 away from the motor is sleeved with a limiting cylinder 28, the inside of the limiting cylinder 28 is installed with a heat-sensitive sheet 29 and a telescopic spring, the telescopic spring is composed of a memory alloy material, the heat-conducting convex shaft 27 is integrally composed of boron nitride material, one end of the heat-conducting convex shaft 27 is fixedly connected with the telescopic spring, the end of the telescopic spring away from the heat-conducting convex shaft 27 is fixedly connected with the heat-sensitive sheet 29, the other end of the heat-conducting convex shaft 27 is in close contact with the armature winding inside the motor, the heat-sensitive sheet 29 is integrally made of nickel-chromium alloy, and the extension end of the heat-sensitive sheet 29 is fixedly connected with the upper inclined plate 210.

[0033] Specifically, as shown in Figure 8 and Figure 9 , the position state of each component when the electric drill body 1 appears temperature overload during operation, as shown in Figure 3 , the heat-conducting convex shaft 27 is located on the side close to the motor, when the motor in the drive module 11 continuously operates, the heat generated by the internal armature winding due to resistance loss continuously accumulates, one end of the heat-conducting convex shaft 27 is closely attached to the armature winding, the other end is fixedly connected with the telescopic spring, and the boron nitride material has excellent heat conduction performance, the heat is efficiently transferred to the position of the telescopic spring and the position of the nickel-chromium alloy heat-sensitive sheet 29, as the temperature of the motor gradually rises, the telescopic spring and the heat-sensitive sheet 29 both begin to gradually heat-expand, since one end of the telescopic spring is fixedly connected to the top of the limiting cylinder 28, the telescopic spring extends downward under the condition of heat expansion, and then gradually pushes the heat-sensitive sheet 29 below, the expansion generated by the telescopic spring pushes the upper inclined plate 210 fixedly connected with the extension end along the extension end, and promotes the upper inclined plate 210 to overcome the stable force in the initial state and move smoothly downward along the vertical direction. At this time, as shown in Figure 6 and Figure 7As shown, the wedge gap formed by the inclined groove 26 of the composite connector 25 provides accurate guidance for the movement of the upper inclined plate 210, and the tip of the upper inclined plate 210 is vertically inserted between the two composite connectors 25 under the constraint of the wedge gap. Since the rigid pipe 23 is rigidly connected to the drill body 1, it provides a stable reference end for the entire circuit. The flexible pipe 24 is movably connected to the motor side wall, which provides a deformable space. Under the continuous extrusion of the upper inclined plate 210, the flexible pipe 24 shrinks in the horizontal direction away from the rigid pipe 23, and the outer composite connector 25 moves synchronously, gradually moving away from the composite connector 25 on the side of the rigid pipe 23. As the depth of the upper inclined plate 210 increases, the distance between the outer adsorbing magnetic rings of the two composite connectors 25 increases, and the magnetic force rapidly decays to the point where it cannot maintain the state of adhesion. The inner layer of the energized contact head is completely separated, the circuit formed by the connecting wire 12 is disconnected, and the motor stops running, achieving temperature overload protection. In this process, the assembly shell 21 buffers the motor vibration through the rubber shock ring pad 22, avoiding vibration interference with the triggering accuracy of the upper inclined plate 210. The arc chute 215 on the outside of the composite connector 25 covers the area where the arc is generated at the moment of contact head separation, quickly extinguishing the arc to protect the contact. When the motor temperature drops to a safe range, the heat-sensitive sheet 29 cools and shrinks, pulling the upper inclined plate 210 back up. The elastic pipe 24 restores to its original state due to its own elasticity, bringing the composite connector 25 back together, and the outer adsorbing magnetic rings are again adsorbed and adhered. The inner layer of the energized contact head is reconnected, the circuit is restored to normal, and the drill can be started again.

[0034] Based on Embodiment 1, please refer to Figure 1 - Figure 11 As shown, when the drill body 1 is overloaded and the drill is stuck, the lower inclined plate 214 is displaced upward and inserted between the two composite connectors 25, causing them to separate and cut off the circuit, achieving overload protection when the drill is stuck.

[0035] It should be noted that the bottom of the assembly shell 21 is equipped with an oval touch plate 211, both ends of which are sleeved with a coil spring 212. One end of the coil spring 212 is fixedly connected to the oval touch plate 211, and the other end is rotatably connected to the ratchet structure in the gear box. The upper part of the oval touch plate 211 is equipped with a spring slide shaft 213, and the lower inclined plate 214 is fixedly connected to the end of the spring slide shaft 213 away from the oval touch plate 211. In the initial state, the spring slide shaft 213 is attached to the short-axis convex surface of the oval touch plate 211. The outer part of the composite connector 25 is equipped with an arc chute 215, which can quickly extinguish the arc when the inner layer of the energized contact head of the composite connector 25 is separated, preventing the contact from being ablated.

[0036] Specifically, as Figure 10 and Figure 11As shown, when the drill body 1 is stuck in the overload, the gear box in the drive module 11 is driven by the motor output shaft to rotate normally, at this time, the elastic slide shaft 213 is attached to the short axis convex surface of the elliptical touch plate 211 due to the pre-tightening force of the coil spring 212, the lower inclined plate 214 keeps a safe distance from the composite connecting piece 25, and the circuit is in a conductive state, as shown in Figure 13 As shown, the pawl mechanism is composed of a ratchet and a pawl assembly, wherein the pawl end is rigidly connected to the elliptical touch plate 211, and the connection position between the pawl and the elliptical touch plate 211 is elastically hinged to the gear box housing through the coil spring 212, forming a one-way force triggering structure. Under normal working conditions, the drill shaft drive gear box output shaft rotates forward, and the ratchet fixed to the output shaft end rotates forward synchronously, the tooth surface of the ratchet is in contact with the pawl head at an inclined angle, and the pawl is pushed to overcome the slight elastic resistance of the coil spring and quickly returns to its original position. During this process, the pawl only makes a small reciprocating swing with the ratchet teeth, the coil spring 212 is always in a pre-tightening energy storage state, and the elliptical touch plate 211 remains in the initial position without triggering the protection action. When the drill shaft is stuck, the main shaft stops rotating due to the sudden increase in resistance, and the gear box output shaft still tries to rotate forward under the inertia of the motor, resulting in an instantaneous reverse torque on the output shaft, forcing the output shaft to drive the ratchet to rotate briefly in the reverse direction. At this time, the vertical stop of the ratchet tooth surface is in rigid contact with the pawl head, and the reverse impact force overcomes the pre-tightening force of the coil spring 212, and the coil spring 212 is further twisted and stored energy synchronously. The elastic potential energy is transmitted to the elliptical touch plate 211 through the pawl, causing the elliptical touch plate 211 to produce an angular deflection, and the long axis direction quickly turns to the lower side of the elastic slide shaft 213. This change in angle causes the long axis convex surface of the elliptical touch plate 211 to quickly press the elastic slide shaft 213, forcing the elastic slide shaft 213 to overcome the initial pre-tightening force and move upward in a straight line. The lower inclined plate 214 fixed to the top end of the elastic slide shaft 213 is simultaneously lifted, and its sharp end is precisely wedged into the wedge gap formed by the inclined surface groove 26 of the composite connecting piece 25.

[0037] With the continuous upward movement of the lower inclined plate 214, the guiding action of the inclined surface groove 26 converts the vertical thrust into a horizontal separating force, which also causes the elastic tube 24 to contract away from the rigid tube 23, driving the two composite connecting pieces 25 to quickly separate. When the inner layer contact head is completely separated, the arc chute 215 immediately suppresses the arc to avoid contact point ablation due to high temperature. At this time, the circuit formed by the connecting wire 12 is cut off, the motor stops outputting power, and the stuck overload protection is completed. After the overload is removed, the output torque of the gear box returns to normal, the elastic deformation of the coil spring 212 gradually returns to its original position, driving the elliptical touch plate 211 to return to the initial angle. The elastic slide shaft 213 loses the extrusion force and slides downward along the guide rail under the action of its own pre-tightening force, driving the lower inclined plate 214 to exit the composite connecting piece 25. The elastic tube 24 restores to its original position relying on its own elasticity, causing the two composite connecting pieces 25 to reattach, the circuit is again conductive, and the drill returns to the normal working state.

[0038] While embodiments of the application have been shown and described, it is to be understood that the application is not limited to the details of the embodiments described, since numerous changes, modifications, substitutions and variations can be made thereto without departing from the spirit and scope of the application as defined by the appended claims and their equivalents.

Claims

1. An overload protection device for an electric drill motor, comprising an electric drill body (1), a drive module (11) is mounted on the side of the electric drill body (1), characterized in that: The inside of the electric drill body (1) is provided with an overload assembly (2), the overload assembly (2) comprises a rigid pipe (23) and an elastic pipe (24), the inside of the rigid pipe (23) and the elastic pipe (24) is provided with a connecting wire (12), and the outside of the side close to each other is equipped with a composite connector (25); the composite connector (25) is a double-layer structure, the inner layer is a power contact for realizing circuit conduction, and the outer layer is an adsorption magnetic ring for adsorption and fixation, and the outside of the composite connector (25) is provided with an upper inclined plate (210) and a lower inclined plate (214) symmetrically; When the electric drill body (1) is overloaded, the upper inclined plate (210) is displaced downward and inserted between the two composite connectors (25), so that the two are separated to cut off the circuit, realizing the temperature overload protection; When the electric drill body (1) is overloaded, the lower inclined plate (214) is displaced upward and inserted between the two composite connectors (25), so that the two are separated to cut off the circuit, realizing the temperature overload protection.

2. The drill motor overload protection device of claim 1, wherein: The driving module (11) is composed of a motor, a gear box and a drill shaft, and the gear box is internally provided with a ratchet structure, and the two ends of the connecting wire (12) are electrically connected with the power supply in the electric drill body (1) and the motor in the driving module (11) respectively.

3. The drill motor overload protection device of claim 1, wherein: The overload assembly (2) further comprises an assembly shell (21), which is slidingly connected between the electric drill body (1) and the driving module (11), and the inside of the assembly shell (21) is fixedly connected with a shock ring pad (22), which is made of rubber material.

4. The drill motor overload protection device of claim 1, wherein: The rigid pipe (23) and the elastic pipe (24) are in the same horizontal plane, the rigid pipe (23) is fixedly connected with the electric drill body (1), and the elastic pipe (24) is movably connected with the side wall of the motor in the driving module (11).

5. The drill motor overload protection device of claim 1, wherein: The outer wall of the composite connector (25) is symmetrically provided with an inclined groove (26), when the composite connector (25) is in a state of sticking together, the inclined grooves (26) form a wedge-shaped shape, which is suitable for the sharp end position of the upper inclined plate (210) and the lower inclined plate (214).

6. The drill motor overload protection device of claim 1, wherein: The side wall of the motor in the driving module (11) is provided with a heat-conducting convex shaft (27), one end of the heat-conducting convex shaft (27) away from the motor is sleeved with a limiting cylinder (28), the inside of the limiting cylinder (28) is provided with a heat-sensitive sheet (29) and a telescopic spring, and the telescopic spring is made of memory alloy material.

7. The drill motor overload protection device of claim 6, wherein: The heat-conducting convex shaft (27) is made of boron nitride material, one end of the heat-conducting convex shaft (27) is fixedly connected with the telescopic spring, the end of the telescopic spring away from the heat-conducting convex shaft (27) is fixedly connected with the heat-sensitive sheet (29), the other end of the heat-conducting convex shaft (27) is in close contact with the armature winding inside the motor, and the heat-sensitive sheet (29) is made of nickel-chromium alloy.

8. The drill motor overload protection device of claim 3, wherein: The bottom of the assembly shell (21) is provided with an oval touch plate (211), both ends of the oval touch plate (211) are sleeved with a coil spring (212), one end of the coil spring (212) is fixedly connected with the oval touch plate (211), and the other end is rotationally connected with a ratchet claw structure in a gear box.

9. The drill motor overload protection device of claim 8, wherein: An elastic sliding shaft (213) is installed above the oval touch plate (211), a lower inclined plate (214) is fixedly connected to one end of the elastic sliding shaft (213) away from the oval touch plate (211), and the elastic sliding shaft (213) is attached to a short-axis convex surface of the oval touch plate (211) in an initial state.

10. The drill motor overload protection device of claim 1, wherein: An arc extinguishing cover (215) is installed outside the composite connecting piece (25), when the internal layer power contact head of the composite connecting piece (25) is separated, the arc extinguishing cover (215) can quickly extinguish electric arc, so that contact ablation is avoided.

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