A switch component, a switch circuit, a power tool control method and a power tool

Abstract

This invention discloses a switching element, a switching circuit, a power tool control method, and a power tool. The switching element includes a housing and a moving contact bridge. The housing contains multiple stationary contacts and a moving contact bridge. Moving contacts are located at both ends of each moving contact bridge, with each stationary contact corresponding to one of the moving contacts. A moving contact closes with its corresponding stationary contact to generate a voltage signal. There are two moving contact bridges, designated as a first moving contact bridge and a second moving contact bridge. Opening or closing the first and second moving contact bridges generates at least three signals. The switching circuit provided by this invention utilizes the switching element and includes a controller connected to the switching element, thereby outputting three control signals: start, stop, and speed adjustment. The power tool provided by this invention utilizes the switching circuit to achieve three operating modes, and the product is more compact.

Description

Technical Field

[0001] The present invention relates to the field of electric tools, and in particular to a switch element, a switch circuit, an electric tool control method and an electric tool. Technical Background

[0002] Currently, most electric tools on the market use a toggle switch for starting and stopping, and another independent rotatable switch for speed regulation. In order to reduce the size of the product, many circuit tools do not have enough space to accommodate two independent switches. In addition, the use of two independent switches to achieve the three working modes of starting, stopping and speed regulation makes the product size larger, which cannot meet the market demand for miniaturization of products.

[0003] Technical Solution

[0004] In order to solve the problem that the product size is larger due to using two independent switches to realize the three working modes of starting, stopping and speed regulation, the present invention provides a switch component, in which one component can output three signals, thereby reducing the product size.

[0005] A switch component, comprising:

[0006] A housing, wherein a plurality of stationary contacts and a moving contact bridge are arranged in the housing;

[0007] A moving contact bridge, wherein moving contacts are arranged at both ends of the moving contact bridge, the stationary contacts correspond to the moving contacts one by one, and the moving contacts are closed with the corresponding stationary contacts to generate a voltage signal;

[0008] There are two moving contact bridges, which are respectively a first moving contact bridge and a second moving contact bridge. The opening or closing of the first moving contact bridge and the second moving contact bridge generates at least three signals.

[0009] Furthermore, when the switch is in the stop position, the moving contact at the first end of the first moving contact bridge is closed with the corresponding static contact, and the moving contact at the second end of the second moving contact bridge is closed with the corresponding static contact, forming a first signal;

[0010] When the switch is in the working position, the moving contact at the second end of the first moving contact bridge is closed with the corresponding static contact, and the moving contact at the second end of the second moving contact bridge is closed with the corresponding static contact, forming a second signal;

[0011] When the switch is in the speed regulating position, the moving contact at the first end of the first moving contact bridge is closed with the corresponding static contact, and the moving contact at the first end of the second moving contact bridge is closed with the corresponding static contact, forming a third signal.

[0012] Further, the first signal is configured as a stop signal, the second signal is configured as a working signal, and the third signal is configured as a speed regulation signal.

[0013] Furthermore, the switch element further comprises:

[0014] A driving body, used for driving the moving contact of the moving contact bridge to close with the corresponding static contact;

[0015] The shifting rod is used to drive the driving body to shift, and the shifting rod passes through the shell and is connected to the driving body.

[0016] Furthermore, the moving contact bridge is an inverted "W"-shaped elastic metal part, the first surface in the middle of the moving contact bridge is formed as a protrusion, and a fixed contact piece is corresponding to the protrusion. The protrusion and the fixed contact piece form a normally closed contact, and the second surface in the middle of the moving contact bridge is formed as a recess, and the driving body is accommodated in the recess and adapted to the shape of the recess. The driving body moves horizontally to close the moving contact at the first end or the second end of the moving contact bridge and the corresponding static contact.

[0017] Furthermore, two limiting protrusions are formed on the second surface of the moving contact bridge, the limiting protrusion located at the speed regulation position is the first protrusion, and the limiting protrusion located at the working position is the second protrusion, the high point of the first protrusion is higher than the high point of the second protrusion, and the distance between the high point of the first protrusion and the normally closed contact is greater than the distance between the high point of the second protrusion and the normally closed contact, the tip of the driving body in the working position passes over the high point of the second protrusion to jam the moving contact bridge, and the limit position of the tip of the driving body in the speed regulation position is on the side of the first protrusion close to the normally closed contact so that the moving contact bridge can be reset.

[0018] Furthermore, the moving contact bridge is installed in a seat body, the fixed contact piece is arranged in the seat body, and a limiting block is integrally formed on at least one side of the moving contact bridge, and both ends of the limiting block abut against the seat body.

[0019] Furthermore, the switch element further comprises six pins, and the six pins are electrically connected to corresponding fixed contact pieces or static contacts respectively.

[0020] The present invention also provides a switch circuit, which uses the above switch element to output three control signals.

[0021] Furthermore, the switch circuit also includes a controller, and the controller forms a control signal according to the signal of the switch element.

[0022] Furthermore, the plurality of stationary contacts are connected to the controller via resistors with the same or different resistance values, and the plurality of stationary contacts are connected to a power source via resistors with the same or different resistance values.

[0023] Furthermore, the fixed contact piece in the housing is grounded.

[0024] The present invention also provides an electric tool control method, which uses the above-mentioned switch circuit. When the switch element is moved to the speed adjustment position, the speed of the electric tool increases based on the current first working speed. When the required working speed is reached, the switch element is released and automatically resets. At this time, the electric tool remains operating at the second working speed.

[0025] Furthermore, when the switch is continuously in the speed regulating position, the speed of the electric tool increases until it reaches the maximum speed, then decreases from the maximum speed to the minimum speed, and then cycles between the minimum speed and the maximum speed.

[0026] The present invention also provides an electric tool, which uses the above-mentioned switch circuit to solve the problem of large product size in the prior art.

[0027] Furthermore, the electric tool also includes a motor and a drive module for driving the motor, the drive module includes at least one drive chip and a three-phase full-bridge inverter circuit, the input end of the drive chip is connected to the output end of the controller, the output end of the drive chip is connected to the input end of the three-phase full-bridge inverter circuit, and the output end of the three-phase full-bridge inverter circuit is connected to the motor.

[0028] Furthermore, the electric tool also includes a temperature protection circuit, which includes a temperature detection element, and the temperature detection element is connected to the controller.

[0029] Furthermore, the electric tool also includes an undervoltage and / or overvoltage protection circuit, which includes a voltage comparator, wherein the reference voltage end of the voltage comparator is connected to a power supply, the compared voltage end of the voltage comparator is connected to an output end of a controller, and the output end of the voltage comparator is connected to an input end of the controller.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The switch element provided by the present invention can switch the working state of the switch element through a lever. The switch element can realize three working states in total, which solves the problem that two independent switches are required to realize three working modes in the prior art, which easily causes a large product volume. The switch element provided by the present invention can reduce the product volume and realize product miniaturization;

[0032] 2. The switch circuit provided by the present invention uses a switch element, and the switch element is connected to a controller. Since the switch element can realize three working states, the controller can realize three output signals, and the three output signals are respectively configured as start, stop and speed regulation signals. The switch circuit provided by the present invention can reduce the volume of the product and realize the miniaturization of the product;

[0033] 3. The electric tool provided by the present invention uses a switch circuit to control the motor to realize three working modes through three output signals of the switch circuit, which solves the problem that the prior art uses two independent switches to realize the three working modes, which easily leads to a large product size. The electric tool provided by the present invention has a smaller product size and can better meet the market demand for miniaturization. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic diagram of the external structure of a switch element provided in an embodiment of the present invention;

[0035] Figure 2 A schematic diagram of a moving contact bridge provided in an embodiment of the present invention;

[0036] Figure 3 A schematic diagram of the internal structure of a switch element provided in an embodiment of the present invention;

[0037] Figure 4 A schematic diagram of a seat provided by an embodiment of the present invention;

[0038] Figure 5 A circuit diagram of a switch circuit provided by an embodiment of the present invention;

[0039] Figure 6 A circuit diagram of a driving module of an electric tool provided in an embodiment of the present invention;

[0040] Figure 7 A schematic diagram of the speed regulation principle of an electric tool provided by an embodiment of the present invention;

[0041] Figure 8 A circuit diagram of a temperature protection circuit for an electric tool provided by an embodiment of the present invention;

[0042] Fig. 9 A circuit diagram of an overvoltage protection circuit for an electric tool provided by an embodiment of the present invention;

[0043] Fig.10 A schematic diagram of a switch and a corresponding diagram of the positions of switch components provided in an embodiment of the present invention.

[0044] In the figure, a is the first pin, b is the second pin, c is the third pin, d is the fourth pin, e is the fifth pin, f is the sixth pin, 1 is the shell, 2 is the moving contact bridge, 2a is the first moving contact bridge, 2b is the second moving contact bridge, 21 is the first protrusion, 22 is the second protrusion, 23 is the protrusion, 24 is the depression, 25 is the limit block, 3 is the lever, 4 is the driving body, 5 is the seat body, 51 is the lifting block, and the hollow limit column 6. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] This embodiment provides a switch element, such as Figure 1 , Figure 2 and Figure 3 As shown, the switch element includes a housing 1 and a moving contact bridge 2 built into the housing 1, and a plurality of stationary contacts are arranged in the housing 1, wherein the middle of the moving contact bridge 2 is electrically connected to the stationary contact piece, and moving contacts are arranged at both ends of the moving contact bridge 2, the stationary contacts correspond to the moving contacts one by one, and the moving contacts are closed with the corresponding stationary contacts to generate a voltage signal, that is, when the moving contact at one end of the moving contact bridge 2 is closed with the stationary contact, the stationary contact, the moving contact, the moving contact bridge 2, the stationary contact piece and its peripheral circuit form a loop, thereby outputting a voltage signal.

[0047] In order to generate different control signals to realize multiple control functions, the moving contact bridge 2 of the present invention is configured as two, and the two moving contact bridges 2 are respectively a first moving contact bridge 2a and a first moving contact bridge 2b. The opening or closing of the first moving contact bridge 2a and the first moving contact bridge 2b generates at least three signals. For example, the moving contact at one end of the first moving contact bridge 2a is closed with the corresponding static contact, and the switch element outputs a first voltage signal at this time, or the moving contact at one end of the first moving contact bridge 2b is closed with the corresponding static contact, and the switch element outputs a second voltage signal at this time, or the moving contact on the same side of the first moving contact bridge 2a and the first moving contact bridge 2b is closed with the corresponding static contact, and the switch element outputs two voltage signals at this time. The above-mentioned different voltage signals and their combinations can form different control signals.

[0048] According to one embodiment of the present invention, when the switch is in the stop position, the moving contact at the first end of the first moving contact bridge 2a is closed with the corresponding static contact, and the moving contact at the second end of the first moving contact bridge 2b is closed with the corresponding static contact, forming a first signal;

[0049] When the switch is in the working position, the moving contact at the second end of the first moving contact bridge 2a is closed with the corresponding static contact, and the moving contact at the second end of the first moving contact bridge 2b is closed with the corresponding static contact, forming a second signal;

[0050] When the switch is in the speed regulating position, the moving contact at the first end of the first moving contact bridge 2a is closed with the corresponding static contact, and the moving contact at the first end of the first moving contact bridge 2b is closed with the corresponding static contact, forming a third signal.

[0051] According to one embodiment of the present invention, the first signal is configured as a stop signal, the second signal is configured as a working signal, and the third signal is configured as a speed regulation signal. The switch element of the present invention realizes both switching and speed regulation. When the switch element is applied to an electric tool or other electrical appliance, the switch and the speed regulation element can be integrated into one, thereby reducing the installation space, making the product miniaturized, and saving manufacturing costs.

[0052] It should be noted that the present invention forms a control signal by combining signals generated by different actions of the first moving contact bridge 2a and the first moving contact bridge 2b, and the combination method can be diversified. For example, when the switch is in the stop position, the moving contact at the second end of the first moving contact bridge 2a is closed with the corresponding static contact, and the moving contact at the first end of the first moving contact bridge 2b is closed with the corresponding static contact, which can also form a first signal and be configured as a stop signal. In other words, as long as the output of at least three control signals can be achieved, there is no limitation to this.

[0053] According to one embodiment of the present invention, a seat body 5 is arranged in the housing 1 of the switch component, and the moving contact bridge 2 is installed in the seat body 5. Preferably, the moving contact bridge 2 of this embodiment is designed as an inverted "W"-shaped elastic metal part, and the first surface in the middle of the moving contact bridge 2 is formed as a protrusion 23, which corresponds to the fixed contact piece in the seat body 5, and the protrusion 23 and the fixed contact piece form a normally closed contact.

[0054] According to an embodiment of the present invention, the switch element further comprises a driving body 4 and a lever 3, wherein the driving body 4 is used to drive the moving contact of the moving contact bridge 2 to close with the corresponding static contact, and the lever 3 is used to drive the driving body 4 to shift, and the lever 3 penetrates the housing 1 and is connected to the driving body 4. Specifically, Figure 2 and Figure 3 As shown, the second surface in the middle of the moving contact bridge 2 is formed as a recess 24, and the driving body 4 is accommodated in the recess 24 and matches the shape of the recess 24. The driving body 4 moves horizontally to close the moving contact at the first end or the second end of the moving contact bridge 2 with the corresponding stationary contact.

[0055] like Figure 3 As shown, this embodiment also includes a hollow limit column 6, through which the lever 3 passes to connect to the driving body 4, and the middle part of the lever 3 is hinged in the hollow limit column 6, and the hollow limit column 6 is fixedly connected to the shell 1. When the lever 3 is in the stop position, the lever 3 is at the center position of the hollow limit column 6. When the lever 3 is in the working or speed regulation position, the lever 3 contacts the edge of the hollow limit column 6. The hollow limit column 6 is used to limit the travel of the lever 3, thereby limiting the travel range of the driving body 4.

[0056] According to one embodiment of the present invention, two limiting protrusions are formed on the second surface of the moving contact bridge 2, the limiting protrusion located at the speed regulating position is the first protrusion 21, and the limiting protrusion located at the working position is the second protrusion 22, the high point of the first protrusion 21 is higher than the high point of the second protrusion 22, and the distance between the high point of the first protrusion 21 and the normally closed contact is greater than the distance between the high point of the second protrusion 22 and the normally closed contact, the tip of the driving body 4 in the working position passes over the high point of the second protrusion 22 to jam the moving contact bridge 2, and the limit position of the tip of the driving body 4 in the speed regulating position is on the side of the first protrusion 21 close to the normally closed contact so that the moving contact bridge 2 can be reset. Through the above structure, a stable state in the working position can be achieved, and speed regulation is convenient at the same time, that is, when the required speed is reached, the lever 3 is released, the switch component is automatically reset, and at the same time the controller of the power tool will memorize the corresponding speed, and it will work according to the memorized speed when it is started again.

[0057] Preferably, Figure 4 As shown, a limiting block 25 is integrally formed on at least one side of the moving contact bridge 2, and both ends of the limiting block 25 abut against the seat body 5. The seat body 5 is also provided with a limiting column perpendicular to the seat body 5. The limiting column limits the middle part of the moving contact bridge 2 in the seat body 5, so that the protrusion 23 formed on the first surface of the middle part of the moving contact bridge 2 and the corresponding fixed contact piece can always be normally closed, that is, the limiting block 25 plays a role of limiting the moving contact bridge 2.

[0058] Preferably, if Figure 4 As shown, a lifting block 51 is provided at least at one end of the seat body 5. When the switch is in the stop position, it is ensured that one end of the moving contact bridge 2 is not in contact with the corresponding static contact, and the other end of the moving contact bridge 2 is in contact with the corresponding static contact. The lifting block 51 is integrally formed with the seat body 5. Of course, the lifting block 51 and the seat body 5 can also be fixed in other ways, and there are no excessive restrictions on this.

[0059] Furthermore, if Figure 1 As shown, the switch element provided in this embodiment includes six pins, and the six pins are electrically connected to the corresponding fixed contact pieces or static contacts, respectively. Specifically, the six pins are a first pin a, a second pin b, a third pin c, a fourth pin d, a fifth pin e and a sixth pin f. In this embodiment, the first end of the first moving contact bridge 2a corresponds to the third pin c, the second end of the first moving contact bridge 2a corresponds to the first pin a, the first end of the first moving contact bridge 2b corresponds to the sixth pin f, and the second end of the first moving contact bridge 2b corresponds to the fourth pin d, and the seat body 5 corresponds to the second pin b and the fifth pin e, respectively.

[0060] Specifically, Fig.10 As shown, when the switch is in the stop position, the second pin b is connected to the third pin c, and the fifth pin e is connected to the fourth pin d;

[0061] When the switch is in the working position, the second pin b is connected to the first pin a, and the fifth pin e is connected to the fourth pin d;

[0062] When the switch is in the speed adjustment position, the second pin b is connected to the third pin c, and the fifth pin e is connected to the sixth pin f.

[0063] This embodiment also provides a switch circuit, using the above switch element, such as Figure 5 As shown, the switch circuit provided in this embodiment also includes a controller. The controller in this embodiment adopts a single-chip microcomputer. Of course, the controller can also adopt other control chips, and there is no excessive restriction on this.

[0064] Furthermore, if Figure 3 As shown, the first pin a, the third pin c, the fourth pin d and the sixth pin f of the switch element are respectively connected to the input end of the controller via resistors, and the first pin a, the third pin c, the fourth pin d and the sixth pin f of the switch element are respectively connected to the power supply via resistors, and the other ends of the second pin b and the fifth pin e of the switch element are grounded.

[0065] It should be noted that in the present invention, it is preferred that the two pins corresponding to the fixed contact pieces are grounded. Of course, the pins corresponding to other static contacts can also be grounded, as long as at least three different control signals can be output, and there is no limitation to this.

[0066] Specifically, Figure 1-5 As shown, when the switch component is in the working position, the switch component outputs a logic signal ABCD=0101 to the controller, and the logic signal ABCD=0101 is configured as a start signal; when the switch component is in the stop position, the switch component outputs a logic signal ABCD=1001 to the controller, and the logic signal ABCD=1001 is configured as a stop signal; when the switch component is in the speed regulation position, the switch component outputs a logic signal ABCD=1010 to the controller, and the logic signal ABCD=1010 is configured as a speed regulation signal.

[0067] This embodiment also provides an electric tool, using the above-mentioned switch circuit. Figure 4 As shown, the electric tool also includes a motor and a drive module for driving the motor.

[0068] As a specific embodiment of the motor of this embodiment, the motor adopts a three-phase two-pole motor and the motor is a brushless motor, that is, there are three groups of coils in the motor, and each group of coils has two magnetic poles.

[0069] As a specific embodiment of the driving module of this embodiment, Figure 4As shown, the driving module includes three driving chips U2~U4 and a three-phase full-bridge inverter circuit. The upper bridge input terminal and the lower bridge input terminal of the three driving chips U2~U4 are connected to the controller D1~D6 terminal. The three-phase full-bridge inverter circuit includes six IGBTs (Insulated Gate Bipolar Transistor) Q1~Q6. The six IGBTs Q1~Q6 are used to control the power on or off of the motor coil. IGBTs Q1~Q3 are upper bridges, and IGBTs Q4~Q6 are lower bridges. The upper bridge output terminal of the driving chip U2 is connected to the gate of IGBTs Q1, and the lower bridge output terminal of the driving chip U2 is connected to the gate of IGBTs Q4. Similarly, the gates of IGBTs Q2 and IGBTs Q5 are connected to the output terminal of the driving chip U3, and the gates of IGBTs Q3 and IGBTs Q6 are connected to the output terminal of the driving chip U4. The three output terminals of the three-phase full-bridge inverter circuit are respectively connected to the U phase, V phase and W phase of the motor. Specifically, the working principle of the driving module is as follows:

[0070] When the controller receives the start signal, it outputs the start command to the driver chip U2~U4. At this time, the current can enter the motor coil through Q1, Q2 or Q3 respectively, and then flow out through Q4, Q5 or Q6. There are six combinations of current entering and exiting the motor, namely Q1->Q5, Q1->Q6, Q2->Q4, Q2->Q6, Q3->Q4 and Q3->Q5, thereby controlling the rotation of the motor;

[0071] When the controller receives the stop signal, it controls IGBTQ1~Q6 to be disconnected, and the motor stops rotating;

[0072] When the controller receives the speed regulation signal, it starts to regulate the speed of the motor. As shown in Figure 5, the controller controls the motor speed to gradually increase by adjusting the frequency of the output PWM wave. When the required working speed is reached, the switch is released and automatically reset. At this time, the power tool remains at the second working speed. The controller detects the input signal once every 0.5s. If the speed regulation signal is continuously detected, the motor speed continues to increase. After the speed of the power tool increases to the highest speed, the timing starts. If the timing time reaches the system setting time, the motor speed is gradually reduced. When the motor speed is about to reach the lowest speed, the speed regulation signal can still be detected, and the motor keeps rotating at the lowest speed. At this time, the timing starts. When the timing time reaches the system setting time, it cycles from the lowest speed to the highest speed.

[0073] Furthermore, during the speed adjustment process of the electric tool provided in this embodiment, the switch component changes its working state. If the current speed is 2000r / min, when the switch component returns to the starting state, the motor keeps rotating at 2000r / min. Even after the electric tool is turned off, the speed of the next startup is still 2000r / min.

[0074] Furthermore, this embodiment also includes a temperature protection circuit, such as Figure 6 As shown, the temperature protection circuit includes a temperature detection element RT3, which is used to detect the temperature of IGBTQ1~Q6 to prevent the temperature from being too high and damaging IGBTQ1~Q6. IGBTQ1~Q6 are power devices that are prone to heat, so they are placed on a radiator. The temperature detection element RT3 is placed on the radiator to detect the temperature. Specifically, the temperature detection element RT3 can be a thermistor, a temperature sensor or an NTC temperature sensor line. The temperature detection element RT3 is connected to the power supply via a resistor RT2, and the resistor RT2 is used for current limiting. At the same time, the temperature detection element RT3 is connected to the controller input terminal via a resistor RT1 to input the detection signal to the controller. When the detection signal is greater than the set value, the controller controls the electric tool to stop working.

[0075] Furthermore, in order to make the power tool work better, the present embodiment also includes an overvoltage protection circuit, which protects the components from breakdown or burning when the power supply is greater than the tolerance voltage of the components. Specifically, the overvoltage protection circuit includes a voltage comparator, and the non-inverting input terminal of the voltage comparator is connected to the power supply via resistor RB10, and the non-inverting input terminal of the voltage comparator is grounded via resistor RB11. Resistors RB10 and RB11 form a series circuit, and the power supply voltage is proportionally reduced and output to the voltage comparator as a reference voltage. The inverting input terminal of the voltage comparator is connected to the output terminal of the controller via resistor RB13, and the controller sends the compared voltage to the voltage comparator. When the reference voltage is greater than the compared voltage, the controller controls the power tool to stop working.

[0076] Furthermore, in order to make the power tool work better, the present embodiment also includes an undervoltage protection circuit. This is because when the voltage input to the controller is lower than the minimum operating voltage of the controller, the controller cannot work normally, and IGBTQ1~Q6 may be turned on and off for a long time due to the untimely response of the controller and then burned out. Therefore, the present embodiment provides an undervoltage protection circuit to protect IGBTQ1~Q6 from being damaged due to undervoltage. The undervoltage protection circuit provided in the present embodiment has the same principle as the overvoltage protection circuit, except that when the reference voltage is lower than the compared voltage output by the controller (the minimum operating voltage of the controller), the controller controls the power tool to stop working.

[0077] In summary, the switch element, switch circuit and electric tool provided by the present invention can make the product more miniaturized.

[0078] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A switch component, characterized in that: include: A housing (1), wherein a plurality of stationary contacts and a moving contact bridge (2) are arranged in the housing (1); A moving contact bridge (2), the middle of the moving contact bridge (2) being electrically connected to a fixed contact piece, moving contacts being arranged at both ends of the moving contact bridge (2), the fixed contacts corresponding to the moving contacts one by one, and the moving contacts closing with the corresponding fixed contacts to generate a voltage signal; There are two moving contact bridges (2), the two moving contact bridges (2) are respectively a first moving contact bridge (2a) and a second moving contact bridge (2b), and the opening or closing of the first moving contact bridge (2a) and the second moving contact bridge (2b) generates at least three signals; The switch element further comprises: A driving body (4) for driving the moving contact of the moving contact bridge (2) to close with the corresponding stationary contact; A shifting rod (3) is used to drive the driving body (4) to shift, and the shifting rod (3) passes through the housing (1) and is connected to the driving body (4); The moving contact bridge (2) is mounted on a base (5), the moving contact bridge (2) is an inverted "W"-shaped elastic metal part, the first surface in the middle of the moving contact bridge (2) is formed as a protrusion (23), the protrusion (23) corresponds to a fixed contact piece on the base (5), the protrusion (23) and the fixed contact piece form a normally closed contact, the second surface in the middle of the moving contact bridge (2) is formed as a recess (24), the driving body (4) is accommodated in the recess (24) and is adapted to the shape of the recess (24), and the driving body (4) moves horizontally to close the moving contact at the first end or the second end of the moving contact bridge (2) with the corresponding fixed contact; The second surface of the moving contact bridge (2) forms two limiting protrusions, the limiting protrusion located at the speed regulating position is the first protrusion (21), and the limiting protrusion located at the working position is the second protrusion (22), the high point of the first protrusion (21) is higher than the high point of the second protrusion (22), and the distance between the high point of the first protrusion (21) and the normally closed contact is greater than the distance between the high point of the second protrusion (22) and the normally closed contact, the tip of the driving body (4) in the working position passes over the high point of the second protrusion (22) to block the moving contact bridge (2), and the limit position of the tip of the driving body (4) in the speed regulating position is located on the side of the first protrusion (21) close to the normally closed contact so that the moving contact bridge (2) can be reset; A limiting block (25) is integrally formed on at least one side of the moving contact bridge (2), and two ends of the limiting block (25) abut against the seat body (5); At least one end of the seat body (5) is provided with a lifting block (51) for preventing one end of the moving contact bridge (2) from contacting the corresponding static contact when the switch is in the stop position, while the other end of the moving contact bridge (2) is in contact with the corresponding static contact.

2. The switch element according to claim 1, characterized in that: When the switch is in the stop position, the moving contact at the first end of the first moving contact bridge (2a) is closed with the corresponding static contact, and the moving contact at the second end of the second moving contact bridge (2b) is closed with the corresponding static contact, forming a first signal, which is configured as a stop signal; When the switch is in the working position, the moving contact at the second end of the first moving contact bridge (2a) is closed with the corresponding static contact, and the moving contact at the second end of the second moving contact bridge (2b) is closed with the corresponding static contact, forming a second signal, which is configured as a working signal; When the switch is in the speed regulating position, the moving contact at the first end of the first moving contact bridge (2a) is closed with the corresponding static contact, and the moving contact at the first end of the second moving contact bridge (2b) is closed with the corresponding static contact, forming a third signal, which is configured as a speed regulating signal.

3. The switch element according to claim 1, characterized in that: It also includes six pins, which are electrically connected to corresponding fixed contact pieces or static contacts respectively.

4. A switch circuit, comprising a switch element as claimed in any one of claims 1 to 3, characterized in that: A controller is also included, and the controller forms a control signal according to the signal of the switch element.

5. The switch circuit according to claim 4, characterized in that: The plurality of stationary contacts are connected to the controller via resistors respectively, and the plurality of stationary contacts are connected to a power source via resistors respectively.

6. The switch circuit according to claim 4, characterized in that: The fixed contact piece in the housing (1) is grounded.

7. A method for controlling an electric tool, comprising the switch circuit according to claim 4, characterized in that: When the switch is turned to the speed adjustment position, the speed of the power tool increases based on the current first working speed to the maximum speed, then decreases from the maximum speed to the minimum speed, and then cycles between the minimum speed and the maximum speed. When the required working speed is reached, the switch is released and it automatically resets, wherein the required working speed is configured as the second working speed, and the controller memorizes the second working speed.

8. An electric tool, characterized in that: Comprising the switching circuit as claimed in claim 4.

9. The electric tool according to claim 8, characterized in that: It also includes a motor and a driving module for driving the motor, the driving module includes at least one driving chip and a three-phase full-bridge inverter circuit, the input end of the driving chip is connected to the output end of the controller, the output end of the driving chip is connected to the input end of the three-phase full-bridge inverter circuit, and the output end of the three-phase full-bridge inverter circuit is connected to the motor.

10. The electric tool according to claim 8, characterized in that: It also includes a temperature protection circuit, which includes a temperature detection element connected to the controller.

11. The electric tool according to claim 8, characterized in that: It also includes a protection circuit, which includes a voltage comparator, a reference voltage terminal of the voltage comparator is connected to a power supply, a compared voltage terminal of the voltage comparator is connected to an output terminal of a controller, and an output terminal of the voltage comparator is connected to an input terminal of the controller.

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