EP4635681A1

EP4635681A1 - Electric tool and method for operating electric tool

Info

Publication number: EP4635681A1
Application number: EP24170952.6A
Authority: EP
Inventors: Raul Cano; Abdessamad Ofir; Stefan Meier; Yuan Liu
Original assignee: Hilti AG
Current assignee: Hilti AG
Priority date: 2024-04-18
Filing date: 2024-04-18
Publication date: 2025-10-22
Also published as: WO2025219110A1

Abstract

An electric tool, comprising: a housing, a driven member supported by the housing, an electric motor, a power source, a brake, and a control unit, which comprises a control circuit for controlling supply of current from the power source to the electric motor. The control circuit comprises a main switch which can be operated by a user, an auxiliary switch which also can be operated by a user, and a brake switch which is coupled to the brake. The control unit further comprises a detection circuit, which is connected to at least one indication device and is configured to detect whether the main switch, auxiliary switch and/or brake switch is opened or closed, and according to a detection result of the detection circuit, the indication device indicates a current state of the electric tool and provides distinguishing indication signals.

Description

TECHNICAL FIELD

The present invention relates to a power tool, and in particular relates to an electrically driven electric tool and a control method for operating this type of electric tool.

BACKGROUND ART

Power tools are generally used for performing various tasks, such as cutting, trimming, mowing, blowing and drilling. Generally, the various power tools used for these tasks may include (but are not limited to) chainsaws, hedge trimmers, lawn mowers, blowers, drilling tools, etc. Power tools comprise manual tools which use manual mechanical force, power-driven tools driven by gasoline/kerosene, electrical driven electric tools, etc. Regarding electrical driven electric tools, many electric tools are configured to have a wireless power source, such as a lithium ion battery pack; the wireless power source provides power equivalent to a wired tool, but has greater convenience and operability.
Power tools generally have a trigger which can be operated by a user for starting one or more work members of the tool. Generally speaking, in a standby mode, that is, when power supplied to the tool is connected but the trigger has not been activated, gasoline/kerosene-driven power tools produce sound and/or vibration. This may indicate to the user that power supplied to the tool is connected. However, electrical driven electric tools can be very quiet. Since electric tools operate quietly, they may not provide the user with the indication of a connected/disconnected state of power. In particular, the user will sometimes pull the trigger unintendedly to actuate the electric tool, and at this time, if the user is touching a work member of the electric tool, there is a high risk of harm on body or damage to property. Therefore, a quiet standby mode of an electric tool sometimes can lead to accidents.
Therefore, there is a need for a safety apparatus for electrical driven electric tools to ensure safe operation of the electric tools. In addition, there is a need for an apparatus for providing a user with an indication of a connected/disconnected state of power supplied to an electric tool.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an electric tool, which has a safer operation control system and can provide prompt feedback to a user, so as to ensure user safety.
An electric tool, comprising: a housing, a driven member supported by the housing, an electric motor, which is connected to the driven member, a power source, which is electrically connected to the electric motor to supply current to the electric motor, a brake, which can be operated by a user, used for braking a movement of the driven member, and a control unit, which comprises a control circuit for controlling supply of current from the power source to the electric motor. The control circuit comprises a main switch which can be operated by a user, an auxiliary switch which also can be operated by a user, and a brake switch which is coupled to the brake. The control unit further comprises a detection circuit, which is connected to at least one indication device and is configured to detect whether the main switch, auxiliary switch and/or brake switch is opened or closed, and according to a detection result of the detection circuit, the indication device indicates a current state of the electric tool to a user, and provides distinguishing indication signals. Thus, when the user activates any switches, they can know which state the tool is in, and according to the distinguishing indication signal, perform a necessary operation.
The electric tool has an awake state and a sleep state, wherein the main switch and auxiliary switch are open in the sleep state, and when the main switch and/or auxiliary switch close in the sleep state, the electric tool changes to the awake state.
When the electric tool is in the awake state, when the detection circuit detects that the brake switch is closed, the electric tool enters a standby state, the indication device displays a first signal indicating the electric tool is ready to run. When the detection circuit detects that the brake switch is open, the indication device displays a second signal indicating a user to close the brake switch, and when the detection circuit detects that the brake switch changes from being open to being closed, the electric tool enters the standby state and the indication device display the first signal indicating the tool is ready to run. Whether the brake switch is closed/open, that is whether the brake is released/locked, is very important for an electric tool which is used repeatedly. If the brake has not been moved to the locked position after previous use, then there is a risk that the main switch and/or auxiliary switch might be activated unintendedly when the electric tool is used again. Therefore, it is necessary to first detect the position of the brake each time the electric tool is used. The user immediately obtains feedback of brake locking or release by means of a distinguishing indication of the indication device and thus knows if the electric tool is not safe. Preferably the first signal is a blinking yellow LED light while the second signal is a steady yellow LED light, so that the user could get a reminder the tool is ready to run but shall be careful with unintended triggering when the indication device displays a yellow blinking light. The driven member can only be driven by the electric motor when the brake is at the released position. Therefore, if when the electric tool is in the awake state, the brake is at the locked position and the indication device displays a yellow steady LED light, a user would know the tool is not ready to run yet, and the user shall operate the brake switch to change the brake switch from being open to being closed, so that the electric tool changes from the awake state to the standby state.
When the electric tool is in the standby state, the main switch and auxiliary switch are closed simultaneously, the control circuit is activated, causing the power source to supply current to the electric motor, and the electric tool changes to a working state. The indication device displays a third signal indicating the electric tool is running in normal operation. Preferably, the third signal is a green steady LED light. When the user has already ascertained the electric tool is ready to run, the user closes the main switch and auxiliary switch at this time, and thereby the three series-connected switches of the control circuit are all closed, the control circuit becomes activated, and the electric tool operates normally.
When the electric tool is in the standby state, if the main switch and auxiliary switch have not been closed after a given period of time, the indication device displays the first signal indicating the electric tool is ready to run. After the electric tool has completed some applications or the user does not actuate the electric tool, the indication device displays the first signal, for example, yellow blinking LED light, to remind the user that the tool is ready to run. If the user would not use the tool for the time being, the yellow blinking signals also reminds the user to open the brake switch, so that the tool cannot be actuated unintendedly when it is woken up next time. This improves the user safety.
Further, the electric tool automatically changes to the sleep state if either the main switch and auxiliary switch or the brake switch is not closed after a second given period of time. In this way, when starting work next time, the electric tool can again detect the position of the brake to ensure safety of the user.
When the electric tool is in the working state, when the brake switch changes from being closed to being open, the electric tool changes to an emergency state. The indicating device display a fourth signal indicating the electric tool stops running in error mode. For example, the fourth signal is a red blinking LED light. If any problem occurs during the process of the electric tool operating, the user operates the brake switch such that the brake moves from a released position to a locked position, and the driven member is mechanically locked and cannot continue moving, preventing the driven member from causing any unwanted harm.
The indication device is an LED light, and the distinguishing indication signals comprise steady light or blinking of different colours. An LED is a simple and convenient indication device, and can provide a user with current state information of the electric tool by way of a simple and clear signal indication.
According to an embodiment of the present invention, the main switch is connected to a main trigger, a user opens or closes the main switch by means of triggering the main trigger, and the auxiliary switch is connected to a safety lock. The safety lock and the main trigger are mechanically locked. Configured in this way, the main switch and auxiliary switch can prevent the electric tool from working unintentionally, for example when transported or placed in a tool room.
The brake has a locked position and a released position, wherein when the brake is at the locked position thereof, the brake switch is open, and when the brake is at the released position thereof, the brake switch is closed. In the present invention, the function of the brake is to physically brake a movement of the driven member. When the brake is at the locked position thereof, the driven member cannot move. When the brake is at the released position thereof, the driven member can move. The user may shift the brake between the locked position and released position by means of operating, for example, a brake handle, which is very useful for a user wishing to quickly brake the driven member.
The present invention further provides a method for operating an electric tool, wherein an electric tool comprises a housing, a driven member supported by the housing, an electric motor, which is connected to the driven member to drive the driven member, a power source, which is electrically connected to the electric motor to supply current to the electric motor, a brake, which can be operated by a user, used for braking a movement of the driven member, and a control unit, which comprises a control circuit for controlling supply of current from the power source to the electric motor, wherein the control circuit comprises a main switch which can be operated by a user, an auxiliary switch which also can be operated by a user, and a brake switch which is coupled to the brake; the control unit further comprises a detection circuit, which is connected to at least one indication device, and the indication device is used to indicate a state of the electric tool to a user, and the method is characterized by comprising the following steps:

(1) closing the main switch and/or auxiliary switch, and the electric tool entering an awake state;
(2) the detection circuit detecting whether the brake switch is open or closed; and the indication device displaying a distinguishing indication; and
(3) when the detection circuit detects that the brake switch is closed or that the brake switch changes from being open to being closed, the electric tool entering a standby state.

By means of the control method of the present invention, a user can immediately obtain feedback information of brake locking or release, and distinguishing indication information according to a locking position and release position, indicating the user to move the brake to the released position, such that the electric tool enters a standby state of being ready to work.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the embodiments mentioned can be gained from the following detailed description with reference to the drawings. It is emphasized that various components are not necessarily drawn to scale. In fact, dimensions may be increased or decreased at will for the purpose of clear description. In the drawings, identical reference numerals denote identical elements.

Fig. 1: shows a three-dimensional drawing of an electric tool, designed as an electrical driven chainsaw, according to a schematic embodiment of the present invention;
Fig. 2: shows a circuit diagram of a method for controlling operation of the electric tool according to the present invention; and
Fig. 3: shows a logic diagram of operation control for the electric tool according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more comprehensively below with reference to the drawings, which show preferred embodiments of the present invention. However, the present invention may be embodied in many different forms herein; on the contrary, these embodiments are provided in order to make the present disclosure full and complete, and comprehensively convey the scope of the invention to those skilled in the art. In the drawings, identical reference signs denote identical components.
Fig. 1 shows an electric tool 1, designed as a chainsaw in the illustration shown, according to the present invention. According to an alternative embodiment, the electric tool 1 may also be designed as a drilling machine, a hammer drill, a saw, a chisel hammer, etc. Although said embodiment is a chainsaw, it should be understood that the present invention may be included in any suitable type of electric tool or power apparatus and is not limited only for use in a chainsaw, and may be included in embodiments of different types. Various other electric tools may be used, such as (but not limited to) a hedge trimmer, mower, blower and angle grinder. In addition, elements or materials of any suitable size, form or type may be used.
The electric tool 1, designed as a chainsaw in the drawings, comprises a housing 2, supporting a driven member 3. In the present schematic embodiment, the driven member 3 comprises a slender support, and a loop of cutting chain on the support. Each chain link of the cutting chain has a cutting element. To drive the driven member 3, an electric motor 4 (not shown in Fig. 1), which is connected to the driven member to drive the driven member, is mounted in the housing 2, and a power source 5 (not shown in Fig. 1) is electrically connected to the electric motor 4 to supply current to the electric motor 4. Preferably, the power source is a battery. Alternatively, the power source may also be an AC power source, that is, the electric tool 1 may also be supplied with current from a power supply network with the aid of a power cable.
The electric tool further comprises a brake 6 for braking the driven member 3, the function of the brake being to physically brake rotation of the cutting chain. The brake 6 has a locked position and a released position; when the brake is at the locked position, the driven member 3 cannot move, and when the brake is at the released position, the driven member 3 can move. As shown in Fig. 1, the brake 6 comprises a brake handle 7 which can be operated by a user; for example, the brake 6 shown in Fig. 1 is at the released position, and if a user pushes the brake handle 7 forward (that is, toward the blade, toward the left in the figure), the brake 6 will be pushed into the locked position. This is very useful if the user wishes to quickly stop the chainsaw.
In addition, the electric tool 1 comprises a control unit 8 and Fig. 2 illustrates the control unit in detail. As shown in Fig. 2, the control unit 8 comprises a control circuit, used for controlling current from the power source 5 to the electric motor 4, and a detection circuit 13. The control circuit comprises three switches connected in series, and therefore, in order to cause current to flow from the power source 5 to the electric motor 4, all three switches must be closed. A main switch 9 which can be operated by a user and an auxiliary switch 10 which can also be operated by a user, wherein the main switch 9 is used for starting the electric motor 4, the auxiliary switch 10 and the main switch 9 are mechanically locked. The main switch 9 can only be closed when the auxiliary switch 10 is closed.
According to a schematic embodiment of the present invention, with reference to Fig. 1, the main switch 9 is configured to connect to a main trigger 12, for example, arranged on a main handle of the electric tool, and a user starts the electric tool by means of triggering the main trigger 12, so that the driven member performs a cutting task. The auxiliary switch 10 is configured to connect to a safety lock (not shown in fig.1), for example, also arranged on the main handle or an auxiliary handle, mechanical locking forming between the safety lock and the main trigger 12. When the safety lock is not triggered, the main trigger 12 cannot move or the stroke of movement thereof is limited. When the safety lock is unlocked, the main trigger 12 can move without restriction. Configured in this way, the main switch 9 and auxiliary switch 10 can prevent the electric tool 1 from working unintentionally, for example when transported or placed in a tool room. Moreover, the main switch 9 and auxiliary switch 10 can only remain in a closed state when the main trigger 12 remains triggered; when the main trigger 12 is released, the main switch 9 immediately opens and remains in an open state, and does not change to being closed until the main trigger 12 is triggered again. When the safety lock is released, the main trigger 12 cannot move, and therefore the main switch and auxiliary switch 10 simultaneously change to an open state.
The third switch is a brake switch 11, which is coupled to the brake, and for example is connected to a brake handle 7. When the brake handle 7 is pushed such that the brake 6 is in the locked position thereof, the brake switch 11 is open, causing the control circuit to enter a non-activated state. This is very useful, because if the brake handle 7 is already activated (pushed away from the user and toward the driven member 3), then it is necessary to stop the movement of the driven member 3. Similarly, if the brake handle 7 is reset, the brake 6 is in its released position, and the brake switch 11 is closed, causing the control circuit to return to an activated state (depending on the state of the auxiliary switch 10). By means of providing the brake switch 11 coupled to the brake handle 7, the electric motor 4 may be stopped while using the brake 6 to stop the driven member 3, so that the driven member may be stopped more quickly. In addition, since the brake 6 mechanically or physically stops the movement of the driven member, a user is unlikely to want to start the electric motor with the brake on, and therefore the brake switch being connected in series to the main switch and auxiliary switch is appropriate, because it can prevent the electric motor from being started with the brake on in any unintentional way, which could cause the electric motor to overheat.
The control unit 8 further comprises a detection circuit 13, which is configured to detect whether the main switch 9, auxiliary switch 10 and/or brake switch 11 is open or closed. The detection circuit 13 is connected to at least one indication device 15, used for indicating the current state of the electric tool to a user according to a detection result of the detection circuit 13, and providing a distinguishing indication signal. Thus, when the user presses/activates any triggers or handle of the brake, they can know which state the tool is in. According to a schematic embodiment of the present invention, the indication device 15 is an LED indication light, and the LED indication light can emit a signal of blinking or steady light of different colours, providing the user with visual feedback of different states the electric tool is in. Alternatively, the indication device 15 may also be a display screen which displays text or symbols, and may further be an apparatus which provides audio feedback, for example a loudspeaker, or the indication device is a combination of apparatuses which provide audio feedback and visual feedback. In addition, the indication device 15 may be mounted on the housing 2, especially on the main handle or auxiliary handle, and may also be mounted on the brake handle, or any position advantageous for being noticed by a user. Moreover, the connection between the indication device 15 and detection circuit 13 may be wired or may be wireless, such as Wi-Fi; therefore, the indication device 15 may even not be mounted on the electric tool, and act as an independent apparatus or application configured on a computer or mobile communication tool.
The electric tool 1 of the present invention has various states, for example, including but not limited to a sleep state, awake state, standby state, working state, emergency state, etc. Corresponding to different states of the electric tool 1, the indication device 15 displays different signals, providing a user with current state information of the electric tool. For example, when the indication device 15 is configured as an LED indication light, a steady yellow light indication means the electric tool is in the awake state and the brake is in a locked position. A blinking yellow light indication means the electric tool is in the awake state and the brake is in the released position. A steady green light indication means the electric tool is in the working state. A red blinking light indication means the electric tool is in the emergency state. The LED indication light being off means the electric tool is in the sleep state.
Below, the method and logic for operating the electric tool are described in detail with reference to Fig. 3. When the electric tool 1 is first used, or when it is ready to use again after a period of time since completing the last task, the electric tool 1 is in the sleep state, and the main switch 9 and auxiliary switch 10 are open at this time, and the indication device 15 designed as an LED light is off (no light). Therefore, for operating the electric tool to operate normally, it is necessary to first wake up the electric tool 1. According to an embodiment of the present invention, a user may trigger the main trigger 12 and/or safety lock, and here no need of unreleased pulling or pressing; briefly touching the main trigger 12 or safety lock causes the main switch 9 and auxiliary switch 10 to briefly close, waking up the electric tool, and the electric tool 1 enters the awake state at this time, and the LED light lights up.
The detection circuit 13 of the control unit detects whether the brake switch 11 is open or closed. When the detection circuit 13 detects that the brake switch 11 is closed, that is, the brake 6 is at the released position thereof, the driven member 3 is not mechanically locked by the brake, so that there is a risk of unintended actuating the electric tool. Therefore, the indication device displays a first signal, for example, blinking yellow LED light, indicating the electric tool 1 is ready to run. By means of the first signal, the user get a reminder the tool is ready to run but shall be careful with unintended triggering the electric tool 1.
When the detection circuit 13 detects that the brake switch 11 is in the open state, that is, the brake 6 is at its locked position, the driven member 3 is mechanically locked by the brake, and the LED light acting as the indication device displays a second signal, for example, a steady yellow light signal at this time, reminding the user that it is necessary to first release locking of the brake. Currently, if the user pushes the brake handle 7 so that the brake moves from the locked position to the released position, the brake switch 11 closes, and the LED light changes to a yellow blinking signal, telling the user that the electric tool 1 has already entered the standby state.
Whether or not the brake switch 11 is closed, that is whether or not the brake 6 is locked, is very important for an electric tool which is used repeatedly. If the brake 6 has not been moved to the locked position after previous use, then there is a risk that the main switch 9 and/or auxiliary switch 10 might be operated by accident when the electric tool is used again. Therefore, it is necessary to first detect the position of the brake 6 each time the electric tool 1 is used. The user immediately obtains feedback of brake locking or release by means of a distinguishing indication of the indication device 15, and thus knows if the electric tool is not safe enough. The driven member 3 can only be driven by the electric motor when the brake 6 is at the released position. Therefore, if when the electric tool 1 is in the awake state, the brake 6 is at the locked position, a user must operate the brake switch 11 to change the brake switch 11 from being open to being closed, so that the electric tool 1 changes to the standby state.
Subsequently, when the electric tool 1 is in the standby state, the main trigger 12 and safety lock are triggered simultaneously, and the main trigger 12 and safety lock are kept triggered, and the main switch 9 and auxiliary switch 10 are closed. At this time, the three switches connected in series are all closed, the control circuit is activated, such that the power source 5 supplies current to the electric motor 4, and thus the electric tool 1 changes to a working state, and at this time, the indication device 15 displays a third signal, for example, a steady green light signal, telling the user that the electric tool operates normally.
When the electric tool 1 is in the working state, if any problem occurs in the process of the electric tool operating, it is necessary to urgently stop the action of the driven member, the user operates the brake handle 7 so that the brake 6 moves from the released position to the locked position, and when the brake switch 11 changes from being closed to being open, the electric tool 1 changes to the emergency state. The driven member is mechanically locked, and cannot continue moving, preventing the driven member from causing any unwanted harm. At this time, the indication device 15 displays a fourth signal, for example, a red blinking LED light, telling the user that operation of the electric tool 1 is restricted and to stop operating the electric tool to prevent damage to the electric motor.
If when the electric tool 1 is in the standby state, after a first given period of time, such as 30 s, the main switch 9 and auxiliary switch 10 have not been closed, that is the user has not triggered the main trigger and unlocked the safety lock, the indication device 15 display the first signal, e.g., yellow blinking LED lights, to remind the user to open the brake switch so that the electric tool cannot be actuated unintendedly.
Further, the electric tool 1 automatically changes to the sleep state if either the main switch 9 and auxiliary switch 10 or the brake switch 11 is not closed after a second given period of time, for example, one minute. In this way, when starting work next time, the electric tool can again detect the position of the brake to ensure safety of the user.
In summary, by means of the control method of the present invention, when the user presses/activates any trigger or handbrake, they can know which state the tool is in.
In the figures and description, preferred embodiments and examples of the present invention are disclosed; although specific terms have been used, they are merely used in a general and descriptive sense and are not intended to define the scope of the present invention; the scope of the present invention is expounded in the attached claims.

Claims

Electric tool (1), comprising: a housing (2), a driven member (3) supported by the housing, an electric motor (4), which is connected to the driven member to drive the driven member, a power source (5), which is electrically connected to the electric motor (4) to supply current to the electric motor (4), a brake (6), which can be operated by a user, used for braking a movement of the driven member (3), and a control unit (8), which comprises a control circuit for controlling supply of current from the power source (5) to the electric motor, wherein the control circuit comprises a main switch (9) which can be operated by a user, an auxiliary switch (10) which also can be operated by a user, and a brake switch (11) which is coupled to the brake, characterized in that the control unit (8) further comprises a detection circuit (13), which is connected to at least one indication device and is configured to detect whether the main switch (9), auxiliary switch (10) and/or brake switch (11) is open or closed, and according to a detection result of the detection circuit, the indication device indicates a current state of the electric tool to a user, and provides a distinguishing indication signal.
Electric tool according to Claim 1, characterized in that the electric tool (1) has an awake state and a sleep state, wherein the main switch (9) and auxiliary switch (10) are open in the sleep state, and when the main switch (9) and/or auxiliary switch (10) close in the sleep state, the electric tool (1) changes to the awake state.
Electric tool (1) according to Claim 2, characterized in that when the electric tool (1) is in the awake state, when the detection circuit detects that the brake switch (11) is closed, the electric tool (1) enters a standby state, and the indication device (15) displays a first signal indicating the electric tool (1) is ready to run.
Electric tool (1) according to Claim 3, characterized in that when the electric tool (1) is in the awake state, when the detection circuit (13) detects that the brake switch (11) is open, the indication device (15) displays a second signal indicating a user to close the brake switch (11), and when the detection circuit (13) detects that the brake switch (11) changes from being open to being closed, the electric tool (1) enters a standby state and the indication device (15) displays the first signal indicating the electric tool (1) is ready to run.
Electric tool (1) according to Claim 3 or 4, characterized in that when the electric tool (1) is in the standby state, the main switch (9) and auxiliary switch (10) are closed simultaneously, the control circuit being activated, the electric tool (1) changes to a working state, and the indicating device displays a third signal indicating the electric tool (1) is running in normal operation.
Electric tool (1) according to Claim 5, characterized in that when the electric tool (1) is in the working state, when the brake switch (11) changes from being closed to being open, the electric tool (1) changes to an emergency state, and the indicating device display a fourth signal indicating the electric tool (1) stops running in error mode.
Electric tool (1) according to any one of the preceding claims, characterized in that when the electric tool (1) is in the standby state, the main switch (9) and auxiliary switch (10) have not been closed after a first given period of time, the indication device (15) displays the first signal indicating the electric tool (1) is ready to run.
Electric tool (1) according to Claim 7, characterized in that the electric tool (1) changes to the sleep state if either the main switch (9) and auxiliary switch (10) or the brake switch (11) is not closed after a second given period of time.
Electric tool (1) according to any one of the preceding claims, characterized in that the indication device (15) is an LED light, and the first to fourth signals comprise of an LED steady light or blinking of different colours.
Electric tool (1) according to any one of the preceding claims, characterized in that the main switch (9) is connected to a main trigger (12), and the auxiliary switch (10) is connected to a safety lock, said main trigger (12) and safety lock are mechanically locked.
Method for operating an electric tool, wherein an electric tool (1) (1) comprises a housing (2), a driven member (3) supported by the housing, an electric motor (4), which is connected to the driven member to drive the driven member, a power source (5), which is electrically connected to the electric motor (4) to supply current to the electric motor (4), a brake (6), which can be operated by a user, used for braking a movement of the driven member (3), and a control unit(8), which comprises a control circuit for controlling supply of current from the power source (5) to the electric motor, wherein the control circuit comprises a main switch (9) which can be operated by a user, an auxiliary switch (10) which also can be operated by a user, and a brake switch (11) which is coupled to the brake; the control unit (8) further comprises a detection circuit (13), which is connected to at least one indication device (15), and the indication device (15) is used to indicate a state of the electric tool (1) to a user, and the method is characterized by comprising the following steps:
(1) closing the main switch (9) and/or auxiliary switch (11), and the electric tool (1) entering an awake state;

(2) the detection circuit (13) detecting whether the brake switch (11) is open or closed; when the detection circuit (13) detects that the brake switch (11)is closed or that the brake switch (11) changes from being open to being closed, the electric tool (1) entering a standby state, the indication device (15) displaying a first signal indicating the electric tool (1) is ready to run; and when the detection circuit (13) detects that the brake switch (11) is open, the indication device (15) displaying a second signal indicating a user to close the brake switch (11).
Method according to Claim 11, characterized in that when the electric tool (1) is in the standby state, the main switch (9) and auxiliary switch (10) are closed simultaneously, the control circuit causes the power source (5) to supply power to the electric motor (4), the driven member (3) can be driven by the electric motor, and the electric tool (1) changes to a working state, and the indication device (15) display a third signal indicating the electric tool (1) is running in normal operation.
Method according to Claim 12, characterized in that when the electric tool (1) is in the working state, when the brake (6) is moved from a released position to a locked position, the electric tool (1) changes to an emergency state, and the indication device (15) display a fourth signal indicating the electric tool (1) stops running in error mode.
Method according to any one of Claims 11-13, characterized in that when the electric tool (1) is in the standby state, if the main switch (9) and auxiliary switch (10) have not been closed after a first given period of time, the indication device (15) displays the first signal indicating the electric tool (1) is ready to run.
Method according to Claim 14, characterized in that electric tool (1) changes to the sleep state if either the main switch (9) and auxiliary switch (10) or the brake switch (11) is not closed after a second given period of time.