CN214707436U - Brushless motor control switch of electric tool - Google Patents

Abstract

The utility model discloses a brushless motor control switch of an electric tool, which comprises a switch main body, an upper cover and a trigger, a deflector rod reversing device for controlling the positive and negative rotation of a brushless motor is arranged in a first cavity of the switch main body, a circuit board assembly and a main circuit breaking mechanism for controlling the circuit board assembly to be connected with a power supply are arranged in a second cavity, the main circuit breaking mechanism is connected with the trigger, the main circuit breaking mechanism comprises a bracket welded and fixed on the circuit board assembly, a first electric contact piece and a second electric contact piece which are electrically connected and fixed with the circuit board assembly, and a movable contact frame connected with the trigger, two springboards are arranged on the bracket, the free end of the springboard is riveted with a movable contact point corresponding to a static contact point on the second electric contact piece, a fulcrum is arranged on the movable contact frame, the tail end of the fulcrum is abutted to the surface of the springboard, when the movable contact frame moves towards the second cavity, the fulcrum drives the springboard to be pressed downwards, and conducting the power supply with the main circuit of the circuit board assembly. The utility model discloses the assembly is simple, easy maintenance, and inner structure is firm.

Description

Brushless motor control switch of electric tool

Technical Field

The utility model relates to a brushless motor control switch field, concretely relates to electric tool's brushless motor control switch.

Background

At present, most of switches and control boards of electric tools using brushless motors in the market are independently and separately designed and assembled, and the switches and the control boards are connected through leads to realize the control of the brushless motors. This kind of switch control structure through pin connection realization brushless motor appears contact failure easily, leads to the product percent of pass not high, simultaneously because too much connecting wire, the whole machine internal wiring is more chaotic, leads to the trouble of assembly easily. In order to solve the problem of disordered internal wiring of the whole machine caused by independent and separate assembly of the switch and the control panel, integrated brushless motor control switches are developed. The brushless motor integrated switch of these improvements on the existing market is equipped with two control panels for realizing motor speed governing and changing motor direction of rotation in switch main part box, and two control panels set up in the installation cavity of difference, connect through the winding displacement, and is with high costs, and the assembly is troublesome, moreover in the use because the vibration of motor leads to the winding displacement to become flexible easily, contact failure is split even to lead to integrated switch inefficacy. In addition, some integrated switches using one circuit board have a large overall volume due to design reasons. The whole machine handle using the switch can not be designed to be very small, or the circuit board is required to be designed to be in the same special shape as the handle, so that the appearance of the switch can not be universal and can not be standardized.

SUMMERY OF THE UTILITY MODEL

In order to solve the defects existing in the technology, the utility model provides an electric tool's brushless motor control switch.

The utility model discloses realize that the technical scheme that above-mentioned technological effect adopted is:

a brushless motor control switch of an electric tool comprises a switch main body, an upper cover and a trigger which are assembled and connected, wherein a first cavity and a second cavity are arranged in the switch main body, a deflector rod reversing device used for controlling the forward and reverse rotation of a brushless motor is arranged in the first cavity, a deflector rod shifting end of the deflector rod reversing device is positioned outside the switch main body, a circuit board assembly and a main circuit breaking mechanism used for controlling the circuit board assembly to be connected with a power supply are arranged in the second cavity, the main circuit breaking mechanism is connected with the trigger, the main circuit breaking mechanism comprises a bracket welded and fixed on the circuit board assembly, a first electric connecting piece and a second electric connecting piece which are electrically connected and fixed with the circuit board assembly, and a movable contact frame connected with the trigger, two springboards are arranged on the bracket, and a movable contact corresponding to a static contact point on the second electric connecting piece is riveted to a free end of the springboard, the movable contact frame is provided with two movable contact frame holes at one end close to the springboard, the movable contact frame holes are internally provided with fulcrums and fulcrum springs, the tail ends of the fulcrums are abutted to the surface of the springboard, when the movable contact frame moves towards the second cavity, the fulcrums drive the springboard to press down, so that the movable contacts are electrically connected with the fixed contacts, a power supply is conducted with a main circuit of the circuit board assembly, and the tail ends of the second electric connecting pieces are further provided with conductive springs which are electrically connected with the circuit board assembly in a normally closed mode.

Preferably, in foretell electric tool's brushless motor control switch, driving lever switching-over device includes the switching-over piece, fixes switching-over shell fragment on the switching-over piece and establish on the circuit board subassembly with first switching-over point, second switching-over point and the third switching-over point that the switching-over shell fragment switching-over electricity is connected, the switching-over piece through its switching-over piece post with the driving lever recess of driving lever inner is fixed when the switching-over shell fragment shift position, the switching-over shell fragment with first switching-over point, second switching-over point is connected simultaneously electrically, or with first switching-over point, third switching-over point is connected simultaneously electrically, the inner of driving lever still is equipped with positioning mechanism.

Preferably, in foretell electric tool's brushless motor control switch, positioning mechanism includes that one is fixed the switching-over steel sheet of first cavity bottom, the switching-over steel sheet is in the orientation one side shaping of driving lever has the location spigot surface that has the unsmooth curved surface of "M" type, the middle part of location spigot surface is equipped with sunken slot, the inner orientation of driving lever the switching-over steel sheet is equipped with the driving lever bellying of extension, the driving lever bellying with the location spigot surface slip butt of switching-over steel sheet.

Preferably, in foretell electric tool's brushless motor control switch, the movable contact frame is located one end in the second cavity is equipped with two recesses, install speed governing shell fragment and shell fragment in the recess respectively, circuit board assembly is corresponding respectively the speed governing shell fragment with the position department of shell fragment is equipped with the speed governing area and the supplementary area that switches on that constitutes by the potentiometre, supplementary conduction takes the slip electricity to be connected with auxiliary switch, the speed governing shell fragment is used for changing the access circuit board assembly's resistance value, through the last control unit output of circuit board assembly is to brushless motor's rotational speed control signal, the shell fragment is used for the switch-on auxiliary switch, for circuit board assembly supplies power.

Preferably, in the brushless motor control switch of the electric power tool, a main spring is disposed in the second cavity, one end of the main spring abuts against a cavity wall of the second cavity, and the other end of the main spring is fixed in a bottom spring hole of the movable contact frame.

Preferably, in the brushless motor control switch of electric tool, the brushless motor control switch further comprises a pressure relief diode, one end of the pressure relief diode is fixed on the bracket, and the other end of the pressure relief diode is electrically connected with the second electric connecting piece through an elastic piece arranged at the bottom of the second electric connecting piece.

Preferably, in the brushless motor control switch of the electric power tool, a partition plate for isolating the main circuit breaking mechanism from the circuit board assembly is further disposed in the second cavity, and an arc extinguishing magnetic block for guiding an arc generated in a process of turning on or off the moving and stationary contacts is disposed at a position close to a tail end of the second electric connecting piece.

Preferably, in the above brushless motor control switch for an electric tool, the control unit and the control chip MCU on the circuit board assembly are respectively disposed on surfaces of different sides, the circuit board assembly is provided with heat dissipation holes at positions corresponding to the control unit, the other side of the circuit board assembly is provided with a heat dissipation transition plate, and the heat dissipation transition plate is connected with heat dissipation fins.

Preferably, in the brushless motor control switch of the electric tool, the circuit board assembly is provided with an expansion opening, the switch main body is formed with a dustproof step at a position where the switch main body is assembled and connected with the upper cover, and the movable contact frame is provided with a dustproof sealing ring at a mounting position where the movable contact frame is connected to the second cavity.

Preferably, in foretell electric tool's brushless motor control switch, three output electricity connection terminal in the switch main part is located the switch main part outside, output electricity connection terminal's tail end be equipped with circuit board assembly welded fastening's welding pin, first connect the electric piece shaping have first power connect the electric terminal and with circuit board assembly welded fastening's welding pin, the second connect the electric piece shaping have the second power connect the electric terminal and with circuit board assembly passes through the fixed pin of conductive spring electricity connection, first power connect the electric terminal with the second power connects the electric terminal and draws forth extremely the outside of switch main part.

The utility model has the advantages that: the utility model discloses a brushless motor control switch settles in the first cavity of switch main part through driving lever switching-over device, settles circuit board subassembly and the main circuit that is used for control circuit board subassembly and power to be connected in the second cavity of switch main part, can prevent driving lever switching-over device to circuit board subassembly and main circuit and divide the interference of mechanism, and the inside welding pin that adopts carries out the electricity with circuit board subassembly and main circuit and divides the mechanism to be connected, compares current winding displacement electricity connected mode, the utility model discloses an integrated switch has the assembly simply, and easy maintenance's advantage can not cause electric connection structure's not hard up because of the vibration of motor in the use, has avoided contact failure and connection fracture's problem. According to different requirements of the whole machine, different configuration modes can be designed and selected, for example, the reversing of the motor can be selected, the mechanical disconnection or electronic disconnection of a main current of a circuit board can be selected, the auxiliary disconnection of the circuit board can be selected, whether a pressure relief diode is assembled or not can be selected, the number of different metal contact points and arc extinguishing magnetic bodies can be selected according to the current of the main circuit, and the small integrated brushless motor control switch is standardized in appearance.

Drawings

FIG. 1 is a view showing the structure of the present invention on the side of an output electric connection terminal;

fig. 2 is an exploded view of the switch main body and the upper cover of the present invention;

fig. 3 is a structural view of the inner partition side of the present invention;

fig. 4 is a structural diagram of the circuit board assembly of the present invention after being assembled on the basis of fig. 3;

fig. 5 is a structural diagram of the present invention after the heat sink is assembled on the basis of fig. 4;

fig. 6 is an internal structure view of the present invention with the partition removed based on fig. 3;

fig. 7 is a structural diagram of the main circuit disconnecting mechanism of the present invention;

fig. 8 is a structural diagram of the main circuit disconnecting mechanism of the present invention at the other side view;

fig. 9 is an exploded view of the internal main circuit breaking mechanism and the shift lever reversing device of the present invention;

fig. 10 is a view of the circuit board assembly of the present invention on the side facing the partition;

fig. 11 is a side view of a circuit board assembly of the present invention;

fig. 12 is a structural view of the circuit board assembly of the present invention on the side facing the heat sink.

Detailed Description

For a further understanding of the invention, reference is made to the following description taken in conjunction with the accompanying drawings and specific examples, in which:

in the description of the present invention, it should be noted that the terms "vertical", "upper", "lower", "horizontal", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, "first," "second," "third," and "fourth" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be further noted that, unless explicitly stated or limited otherwise, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected, mechanically connected, electrically connected, directly connected, connected through an intermediate medium, or connected to the inside of two elements. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

To further understand the contents, features and functions of the present invention, the following embodiments are described in detail:

referring to fig. 1 to 12, a brushless motor control switch for an electric tool according to an embodiment of the present invention includes a switch main body 3, an upper cover 25 and a trigger 1, which are assembled and connected. As shown in fig. 2, the switch body 3 is provided with a first cavity 3-1 and a second cavity 3-2, and a shift lever reversing device for controlling the forward and reverse rotation of the brushless motor is installed in the first cavity 3-1. The poking end of a poking rod 2 of the poking rod reversing device is positioned outside the switch main body 3, a circuit board assembly 28 and a main circuit breaking mechanism for controlling the circuit board assembly 28 to be connected with a power supply are arranged in the second cavity 3-2, and the main circuit breaking mechanism is connected with the trigger 1. As shown in fig. 6 and 9, the main circuit breaking mechanism includes a bracket B40 soldered to the circuit board assembly 28, a first electric contact B33 and a second electric contact B34 electrically connected to the circuit board assembly 28, and a movable contact 19 connected to the trigger 1. Two gangboards 12-1 are arranged on the bracket B40, and the free end of the gangboard 12-1 is riveted with a movable contact 22 corresponding to the fixed contact 21 on the second electric connecting piece B34. The movable contact frame 19 is provided with two movable contact frame holes 19-1 at one end close to the springboard 12-1, a fulcrum 17 and a fulcrum spring 18 are arranged in the movable contact frame hole 19-1, and the tail end of the fulcrum 17 is abutted against the surface of the springboard 12-1. When the movable contact frame 19 moves towards the second cavity 3-2, the fulcrum 17 drives the springboard 12-1 to press down, so that the movable contact 22 is electrically connected with the fixed contact 21, and the power supply is conducted with the main circuit of the circuit board assembly 28.

Specifically, as shown in fig. 9, the shifter lever reversing device includes a reversing block 8, a reversing elastic sheet 9 fixed on the reversing block 8, and a first reversing point 28-1, a second reversing point 28-2, and a third reversing point 28-3 disposed on the circuit board assembly 28 and electrically connected to the reversing elastic sheet 9 in a reversing manner. The reversing block 8 is fixed with a deflector rod groove 2-1 at the inner end of the deflector rod 2 through a reversing block column 8-1, and when the deflector rod 2 is stirred left and right, the reversing block 8 can be driven to move left and right due to the principle of a cam mechanism. The direction-changing elastic sheet 9 moves left and right along with the movement, and the direction-changing elastic sheet 9 presses on the circuit board assembly 28. When the reversing elastic sheet 9 moves to a certain position, the reversing elastic sheet 9 is electrically connected with the first reversing point 28-1 and the second reversing point 28-2 at the same time, or is electrically connected with the first reversing point 28-1 and the third reversing point 28-3 at the same time. Different signals are sent to the circuit board assembly 28 at different conduction positions, and the single chip microcomputer outputs different controls according to different sampled signals, so that the brushless motor can realize forward rotation or reverse rotation.

Further, as shown in fig. 6, 9 and 10, three output electrical connection terminals 30U, 31V, 32W on the switch body 3 are located outside the switch body, and the tail ends of the output electrical connection terminals 30U, 31V, 32W are provided with soldering pins 30U-1, 31V-1, 32W-1 soldered to the circuit board assembly 28. The first electrical contact B33 is formed with a first power electrical terminal B33-1 and a first solder pin B33-2 soldered to the circuit board assembly 28. The second electric connecting piece B34 is formed with a second power electric terminal B34-1 and a fixing pin B34-2 electrically connected and fixed with the circuit board assembly 28 by a conductive spring 5. The bracket B40 is formed with a soldering pin B40-1, and the soldering pin B40-1 is soldered to the circuit board assembly 28. The first power supply electrical terminal B33-1 and the second power supply electrical terminal B34-1 are led out to the outside of the switch main body 3 for connection with a power supply line. Specifically, the solder pin 30U-1, the solder pin 31V-1, the solder pin 32W-1, the first solder pin B33-2, the solder pin B40-1, and the conductive spring 5 are respectively soldered to the circuit board of the circuit board assembly 28 via corresponding pin solder points on the circuit board assembly 28.

As shown in FIG. 10, the corresponding pin pads on circuit board assembly 28 are disposed on the side of circuit board assembly 28 opposite bulkhead 24, including pin pad 36, pin pad 36-11, pin pad 36-12, pin pad 36-13, pin pad 36-14, and pin pad 36-15. The welding pin 30U-1 is fixedly welded with the signal electric connection contact point 36-1, the welding pin B40-1 is fixedly welded with the pin welding point 36-12, the welding pin 31V-1 is fixedly welded with the pin welding point 36-13, the welding pin 32W-1 is fixedly welded with the pin welding point 36-14, the conductive spring 5 is fixedly electrically connected with the pin welding point 36, and the first welding pin B33-2 is fixedly welded with the pin welding point 36-15. To increase the structural stability of circuit board assembly 28 in second cavity 3-2, circuit board assembly 28 is formed with socket-type electrical connection holes at pin pad 36, pin pad 36-11, pin pad 36-12, pin pad 36-13, pin pad 36-14, and pin pad 36-15, and the corresponding solder pins are plugged into the corresponding electrical connection holes, soldered, fixed, and electrically connected. By respectively inserting and welding each welding pin into the corresponding pin welding point formed by the electric connection hole, the electric connection between each pin welding point on the circuit board assembly 28 and each welding pin of the main circuit breaking mechanism in the second cavity 3-2 can be realized, and the circuit board assembly 28 and the main circuit breaking mechanism can be firmly welded and fixed.

In order to fix the deflector rod 2 after being adjusted in place, the inner end of the deflector rod 2 is also provided with a positioning mechanism. Specifically, as shown in fig. 9, the positioning mechanism includes a direction-changing steel plate 7 fixed at the bottom of the first cavity 3-1, and the direction-changing steel plate 7 is formed with a positioning guide surface 7-1 having an M-shaped concave-convex curved surface on the side facing the shift lever 2. The middle part of the positioning guide surface 7-1 is provided with a concave groove 7-2, the inner end of the deflector rod 2 is provided with an extended deflector rod convex part 2-2 facing the reversing steel sheet 7, and the deflector rod convex part 2-2 is in sliding butt joint with the positioning guide surface 7-1 of the reversing steel sheet 7. The deflector rod protrusion 2-2, the concave groove 7-2 on the reversing steel sheet 7 and the positioning guide surface 7-1 are matched together, so that the position of the reversing block 8 can be prevented from moving due to the fact that the deflector rod 2 cannot be moved to the position or vibration and the like in the running process of a machine, and unstable work of a circuit board is avoided.

Further, as shown in fig. 6 and 10, the movable contact frame 19 has two grooves at one end thereof located in the second cavity 3-2, the grooves are respectively installed with the speed regulation spring 10 and the spring 11, and the circuit board assembly 28 is provided with a speed regulation belt 28-5 and an auxiliary conduction belt 28-4, which are formed by potentiometers, at positions corresponding to the speed regulation spring 10 and the spring 11, respectively. The auxiliary conduction band 28-4 is slidably connected with an auxiliary switch 28-6, the speed regulation elastic sheet 10 is used for changing the resistance value of the access circuit board assembly 28, a control unit 28-7 on the circuit board assembly 28 outputs a rotating speed control signal for the brushless motor, and the elastic sheet 11 is used for switching on the auxiliary switch 28-6 to supply power to the circuit board assembly 28 and provide a switching-on signal.

Specifically, as shown in fig. 6, a main spring 6 is disposed in the second cavity 3-2, one end of the main spring 6 abuts against the cavity wall of the second cavity 3-2, and the other end is fixed in a bottom spring hole of the movable contact frame 19. When the trigger 1 is pressed, the trigger 1 drives the movable contact frame 19 to compress the main spring 6, the main spring 6 stores energy, and when the pressing force on the trigger 1 is removed, the trigger 1 moves outwards to return to the original position.

Specifically, in the preferred embodiment of the present invention, as shown in fig. 6, 8 and 9, the present invention further comprises a voltage relief diode 15, one end of the voltage relief diode 15 is fixed on the bracket B40, and the other end of the voltage relief diode 15 is electrically connected to the second electric connecting piece B34 through an elastic piece 38 disposed at the bottom of the second electric connecting piece B34. The voltage relief diode 15 provides a voltage relief channel for reverse voltage during motor speed regulation, protects the control element 28-7 from high voltage, protects the element, and can reduce the requirement of the element on voltage breakdown resistance.

Further, as shown in fig. 3, after the switch body 3 is provided with metal members, a partition 24 is provided at a contact portion, and the partition 24 is used for isolating contact sparks to prevent sparks from splashing on the circuit board assembly 28 when the movable contact 22 and the fixed contact 21 are connected and disconnected. As shown in fig. 9, an arc extinguishing magnetic block 20 is provided at a position near the end of the second electric contact piece B34, and the arc extinguishing magnetic block 20 is used for guiding the flying direction of the arc during the contact opening and closing process and reducing the generation of the arc. As shown in fig. 10 to 12, the control unit 28-7 and the control chip MCU 28-8 on the circuit board assembly 28 are respectively disposed on different side surfaces, the circuit board assembly 28 is provided with heat dissipation holes at positions corresponding to the control units 28-7, a heat dissipation transition plate 37 is provided at the other side of the circuit board assembly 28, and the heat dissipation transition plate 37 is connected with the heat sink 26 to conduct heat generated by the components on the circuit board assembly 28 during operation to the outside for dissipation.

As shown in fig. 1 and fig. 2, the circuit board assembly 28 is provided with an expansion port 4, and the expansion port 4 is used for inputting a control program to the control chip MCU 28-8 after the switch is assembled, and also used for expanding the input of external sampling (temperature, external signal, etc.) of the switch and the control of the lighting lamp of the whole lighting device. In order to prevent dust from entering, the whole circle of dustproof steps 3-3 are arranged around the switch main body 3, corresponding steps are arranged on the upper cover 25 to form a dustproof labyrinth, and the movable contact frame 19 is provided with a dustproof sealing ring 13 at the installation position connected with the second cavity 3-2, so that external dust is prevented from entering the switch from the gap between the upper cover and the main body and the installation position of the movable contact frame 19 and the second cavity 3-2.

In the actual model selection process, the pressure relief diode 15 in the switch of the utility model is an optional part, and when using the element with higher withstand voltage ratio, the device can be omitted. The deflector rod reversing device comprises a deflector rod 2, a reversing block 8 and a reversing elastic sheet 9, and the deflector rod reversing device can be omitted on occasions where the motor does not need to be reversed. The springboard 12-1, the fulcrum 17, the fulcrum spring 18, the bracket B40 and the second electric connecting piece B34 can be omitted in a switch without the disconnection of a main circuit, and one electric connecting piece can be directly used for replacing the switch. The arc extinguishing magnet 20 for extinguishing and guiding the arc may not be installed when the current passing through the switch is relatively small.

The basic principles, main features and advantages of the present invention have been shown and described above, and it should be understood by those skilled in the art that the present invention is not limited by the above embodiments, but only by the principles of the present invention, and that various changes and modifications may be made without departing from the spirit and scope of the invention, which fall within the scope of the invention as claimed, and the scope of the invention is defined by the appended claims and their equivalents.

Claims (10)

1. A brushless motor control switch of an electric tool comprises a switch main body (3), an upper cover (25) and a trigger (1) which are assembled and connected, wherein a first cavity (3-1) and a second cavity (3-2) are arranged in the switch main body (3), a driving lever reversing device used for controlling the positive and negative rotation of a brushless motor is arranged in the first cavity (3-1), the driving end of a driving lever (2) of the driving lever reversing device is positioned outside the switch main body (3), a circuit board assembly (28) and a main circuit breaking mechanism used for controlling the circuit board assembly (28) to be connected with a power supply are arranged in the second cavity (3-2), the main circuit breaking mechanism is connected with the trigger (1), and the brushless motor control switch is characterized in that the main circuit breaking mechanism comprises a support (B40) welded and fixed on the circuit board assembly (28), A first electric contact (B33) and a second electric contact (B34) which are electrically connected and fixed with the circuit board assembly (28), and a movable contact frame (19) connected with the trigger (1), wherein two jumpers (12-1) are arranged on the support (B40), the free end of each jumpers (12-1) is riveted with a movable contact (22) corresponding to a fixed contact (21) on the second electric contact (B34), one end of each movable contact frame (19) close to the corresponding jumpers (12-1) is provided with two movable contact frame holes (19-1), a fulcrum (17) and a fulcrum spring (18) are arranged in each movable contact frame hole (19-1), the tail end of each fulcrum (17) is abutted to the surface of the corresponding jumpers (12-1), and when the movable contact frame (19) moves towards the second cavity (3-2), each jumper (12-1) is driven to be pressed downwards by the fulcrum (17), the movable contact (22) is electrically connected with the fixed contact (21) to conduct power with a main circuit of the circuit board assembly (28), and the tail end of the second electric connecting piece (B34) is also provided with a conductive spring (5) which keeps normally closed electrical connection with the circuit board assembly (28).

2. The brushless motor control switch of claim 1, wherein the lever reversing device comprises a reversing block (8), a reversing spring (9) fixed to the reversing block (8), and a first reversing point (28-1), a second reversing point (28-2), and a third reversing point (28-3) provided on the circuit board assembly (28) and electrically connected to the reversing spring (9) in a reversing manner, the reversing block (8) is fixed to a lever groove (2-1) at an inner end of the lever (2) by a lever column (8-1), and when the reversing spring (9) is in a moving position, the reversing spring (9) is electrically connected to the first reversing point (28-1), the second reversing point (28-2) at the same time, or is electrically connected to the first reversing point (28-1), or the second reversing point (28-2) at the same time, The third reversing point (28-3) is electrically connected at the same time, and the inner end of the deflector rod (2) is also provided with a positioning mechanism.

3. The brushless motor control switch of the electric tool according to claim 2, wherein the positioning mechanism comprises a direction-changing steel sheet (7) fixed at the bottom of the first cavity (3-1), the direction-changing steel sheet (7) is formed with a positioning guide surface (7-1) having an M-shaped concave-convex curved surface at a side facing the direction-changing lever (2), a concave groove (7-2) is formed in the middle of the positioning guide surface (7-1), an inner end of the direction-changing lever (2) is provided with a direction-changing lever protrusion (2-2) extending towards the direction-changing steel sheet (7), and the direction-changing lever protrusion (2-2) is in sliding contact with the positioning guide surface (7-1) of the direction-changing steel sheet (7).

4. The brushless motor control switch of the electric tool according to claim 1, wherein the moving contact holder (19) has two grooves at one end located in the second cavity (3-2), the grooves are respectively installed with a speed-adjusting spring (10) and a spring (11), the circuit board assembly (28) is provided with a speed-adjusting band (28-5) and an auxiliary conduction band (28-4) composed of potentiometers at positions respectively corresponding to the speed-adjusting spring (10) and the spring (11), the auxiliary conduction band (28-4) is slidably connected with an auxiliary switch (28-6), the speed-adjusting spring (10) is used for changing a resistance value connected to the circuit board assembly (28), and a control signal for controlling the rotation speed of the brushless motor is output through a control unit (28-7) on the circuit board assembly (28), the elastic sheet (11) is used for connecting the auxiliary switch (28-6) to supply power to the circuit board assembly (28).

5. The brushless motor control switch of the electric tool according to claim 1, wherein a main spring (6) is arranged in the second cavity (3-2), one end of the main spring (6) abuts against the cavity wall of the second cavity (3-2), and the other end of the main spring is fixed in a bottom spring hole of the movable contact frame (19).

6. The brushless motor control switch of an electric tool according to claim 1, further comprising a voltage relief diode (15), wherein one end of the voltage relief diode (15) is fixed on the bracket (B40), and the other end of the voltage relief diode (15) is electrically connected with the second electric connecting piece (B34) through an elastic piece (38) arranged at the bottom of the second electric connecting piece (B34).

7. The brushless motor control switch of the electric tool according to claim 1, wherein a partition plate (24) for isolating the main circuit breaking mechanism from the circuit board assembly (28) is further provided in the second cavity (3-2), and an arc extinguishing magnet (20) for guiding an arc generated during the process of turning on or off the moving and stationary contacts is provided near a distal end position of the second electric connecting piece (B34).

8. The brushless motor control switch of an electric tool according to claim 4, wherein the control unit (28-7) and the control chip MCU (28-8) on the circuit board assembly (28) are respectively disposed on surfaces of different sides, the circuit board assembly (28) is provided with heat radiating holes at positions corresponding to the control units (28-7), a heat radiating transition plate (37) is provided at the other side of the circuit board assembly (28), and the heat radiating transition plate (37) is connected with a heat radiating fin (26).

9. The brushless motor control switch of an electric tool according to claim 1, wherein the circuit board assembly (28) is provided with a hole (4) for expansion, the switch body (3) is formed with a dust-proof step (3-3) at a position where the switch body is assembled with the upper cover (25), and the movable contact holder (19) is provided with a dust-proof seal ring (13) at a mounting position where the movable contact holder is inserted into the second cavity (3-2).

10. The brushless motor control switch of an electric tool according to claim 2, wherein three output electric connection terminals (30U, 31V, 32W) on the switch body (3) are located outside the switch body, the tail ends of the output electric connection terminals (30U, 31V, 32W) are provided with welding pins (30U-1, 31V-1, 32W-1) welded and fixed with the circuit board assembly (28), the first electric connection pad (B33) is formed with a first power electric connection terminal (B33-1) and a first welding pin (B33-2) welded and fixed with the circuit board assembly (28), the second electric connection pad (B34) is formed with a second power electric connection terminal (B34-1) and a fixing pin (B34-2) electrically connected and fixed with the circuit board assembly (28) through the conductive spring (5), the first power supply electrical terminal (B33-1) and the second power supply electrical terminal (B34-1) are led out to the outer side of the switch main body (3).

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