Switch assembly for electric tool and electric tool

Abstract

The invention provides a switch assembly for an electric tool and the electric tool, and the switch assembly for the electric tool comprises a speed switch which is configured to generate a speed request signal; and a control unit configured to execute the following operations within a preset period of time since the electric tool is powered on again after being powered off: only receiving the speed request signal from the speed switch; determining that the speed request signal is greater than or equal to a threshold value; and prohibiting a motor of the electric tool from running. According to the switch assembly for the electric tool and the electric tool, a flexible and practical power-off restart protection function can be provided under the condition that a power-off restart protection circuit is omitted.

Description

Technical Field

[0001] The present application relates to a switch assembly for an electric tool and the electric tool. Background Art

[0002] At present, a power source such as a battery can be used to power a cordless power tool, and a power switch for the power source can be provided for the cordless power tool. When the power switch is disconnected, the cordless power tool is powered off, and when the power switch is connected / closed, the cordless power tool is powered on. Some cordless power tools have a power-off restart protection function, that is, if the power switch is not disconnected, but the cordless power tool is accidentally powered off and then powered on again, the motor of the cordless power tool will not start directly, and the user needs to disconnect the power switch and then connect it again to allow the motor to restart.

[0003] The turning on of the power switch can trigger the generation of a contact signal, but it is not possible to determine whether the turning on of the power switch occurs before the cordless power tool is powered on again by the contact signal alone. In the prior art, a variety of hardware circuits, namely, a power-off restart protection circuit, are generally used in conjunction with the contact signal to determine whether the turning on of the power switch occurs before the cordless power tool is powered on again, and the power-off restart protection function is triggered based on this determination. Summary of the invention

[0004] The present application proposes a switch assembly for an electric tool and an electric tool, which can provide a flexible and practical power-off restart protection function without using a power-off restart protection circuit.

[0005] According to one aspect of the present application, a switch assembly for an electric tool is provided, the switch assembly comprising: a speed switch configured to generate a speed request signal; and a control unit configured to perform the following operations within a preset time period since the electric tool is powered off and then powered on again: only receive the speed request signal from the speed switch; determine that the speed request signal is greater than or equal to a threshold; and prohibit the operation of the motor of the electric tool.

[0006] Optionally, the speed switch is configured to be pressed by a user to move a certain stroke, and the speed request signal changes continuously based on the stroke.

[0007] Optionally, the switch assembly further comprises: a locking mechanism configured to lock the speed switch when the speed switch moves at least a portion of the stroke.

[0008] Optionally, said threshold is determined based on said at least part of said trip.

[0009] According to another aspect of the present application, a switch assembly for an electric tool is provided, the switch assembly comprising: a speed switch configured to generate a speed request signal; and a control unit configured to perform the following operations within a preset time period since the electric tool is powered on again after being powered off: only receiving the speed request signal from the speed switch at at least two time points; and controlling the motor of the electric tool to operate at a speed requested by the speed request signal received at the last time point of the at least two time points, at least based on a change in the speed request signal received at the at least two time points being greater than or equal to a threshold.

[0010] Optionally, only receiving the speed request signal from the speed switch at at least two time points includes: only receiving the speed request signal from the speed switch at at least three time points; and at least based on the change of the speed request signal received at the at least two time points being greater than or equal to a threshold, controlling the motor of the power tool to run at the speed requested by the speed request signal received at the last time point of the at least two time points includes: based on the change of the speed request signal received at two adjacent time points among the at least three time points being greater than or equal to the threshold, controlling the motor of the power tool to run at the speed requested by the speed request signal received at the last time point of the at least three time points.

[0011] Optionally, only receiving the speed request signal from the speed switch at at least two time points includes: only receiving the speed request signal from the speed switch at at least three time points; and at least based on the change of the speed request signal received at the at least two time points being greater than or equal to a threshold, controlling the motor of the power tool to run at the speed requested by the speed request signal received at the last time point of the at least two time points includes: based on the change of the speed request signal received at two adjacent time points among the at least three time points being greater than or equal to the threshold, and based on whether the speed request signal received at the at least three time points is in a state of gradually increasing over time, controlling the motor of the power tool to run at the speed requested by the speed request signal received at the last time point of the at least three time points.

[0012] Optionally, the switch assembly further comprises: a power switch configured to connect and disconnect the power of the electric tool so as to power on or off the electric tool.

[0013] Optionally, the control unit is further configured to filter the speed request signal by means of a filtering algorithm.

[0014] Optionally, the switch assembly further comprises a filter circuit configured to filter the speed request signal.

[0015] According to another aspect of the present application, there is provided an electric tool, which includes the above-mentioned switch assembly for the electric tool.

[0016] The switch assembly for an electric tool and the electric tool provided in the present application utilize a speed request signal from a speed switch to determine whether to trigger a power-off restart protection function, thereby eliminating the need for a power-off restart protection circuit and taking into account scenarios in which the speed switch is fully pressed or half-pressed, thereby providing high flexibility and practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which constitute a part of the specification, illustrate embodiments of the present application and, together with the description, serve to explain the principles of the present application.

[0018] Figure 1 is a schematic cross-sectional view of a portion of a power tool (ie, a switch assembly) according to one embodiment of the present application.

[0019] Figure 2 yes Figure 1 Another schematic cross-sectional view of the portion of the power tool.

[0020] Figure 3 is a structural block diagram of an electric tool according to one embodiment of the present application.

[0021] Figure 4 It is a working flow chart of a control unit for an electric tool according to one embodiment of the present application.

[0022] Figure 5 is a flowchart of a control unit for an electric tool according to another embodiment of the present application.

[0023] Other features and advantages of the present application will become apparent from the following detailed description of exemplary embodiments of the present application with reference to the accompanying drawings. DETAILED DESCRIPTION

[0024] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0025] Techniques and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the techniques and equipment should be considered part of the specification.

[0026] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0027] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0028] Reference Figure 1 and Figure 2 A feasible implementation of the power tool of the present application is described, wherein the power tool includes a switch assembly 100, which includes a single shell 1, the shell 1 has a front wall 1a and a rear wall 1b, all electronic parts of the switch assembly 100 are sealed in the shell 1, and the control part of the switch assembly 100 extends out of the shell 1 through the front wall 1a for user operation.

[0029] Here, the switch assembly 100 includes a power switch 2 and a speed switch 3 arranged side by side, and a circuit board 5 arranged facing the main body of the power switch 2 and the speed switch 3, wherein the power switch 2 and the circuit board 5 are arranged in a housing 1.

[0030] The main body 6 of the speed switch 3 is arranged in the housing 1 and can slide longitudinally in the housing 1 toward the front wall 1a or the rear wall 1b through a guide structure 7 (e.g., guide groove, guide protrusion, etc.) that cooperates with a guide portion in the housing 1.

[0031] The main body 6 is provided with a magnet 8 , which cooperates with a linear Hall element 9 arranged on the circuit board 5 .

[0032] The speed switch 3 is also equipped with a return spring 11 arranged around the positioning rod 10 mounted on the rear wall 1b. The thrust generated by the return spring 11 tends to force the main body 6 to move toward the front wall 1a.

[0033] The end surface of the main body part 6 facing the front wall 1a is connected to the push rod 12. The push rod 12 passes through the front wall 1a and is exposed to the outside of the housing 1. The end 12a of the push rod 12 is fixed in the button 13.

[0034] The button 13 can be configured to be suitable for being pressed by a user's finger and moving toward the front wall 1a. For this reason, one or more guide posts 14 are formed on the front wall 1a, and the guide posts 14 are inserted into the guide structure in the button 13 for guiding the movement of the button 13 relative to the housing 1.

[0035] In order to seal the push rod 12 relative to the front wall 1a, a flexible sealing sleeve 15, such as a bellows-shaped sealing sleeve, is installed between the flange portion 12b of the push rod 12 close to the end 12a and the front wall 1a.

[0036] The rear end of the return spring 11 is supported by the bottom flange of the positioning rod 10 , and the front end of the return spring 11 is inserted into the main body portion 6 , or even inserted into the push rod 12 .

[0037] In the free release position of the speed switch 3, that is, when the button 13 is not pressed by the user, the reset spring 11 keeps the button 13 at a certain distance from the front wall 1a through the push rod 12. At this point, it can be understood that a limit structure (not shown) for limiting the extreme position of the main body 6 moving toward the front wall 1a is provided in the housing 1. In the free release position of the speed switch 3, the magnet 8 is away from the linear Hall element 9, and the magnetic field does not trigger the linear Hall element 9.

[0038] The user presses the button 13 to overcome the thrust of the return spring 10 so that the speed switch 3 and specifically the main body 6 slides a certain distance in the direction toward the rear wall 1b (the longitudinal pressing direction), and the magnet 8 gradually approaches the linear Hall element 9. The magnetic field strength of the magnet 8 acting on the linear Hall element 9 increases accordingly, and the output voltage of the linear Hall element 9 also changes accordingly, thereby outputting a continuously variable speed request signal on the circuit board 5, for example, a continuously variable analog signal. That is, as the speed switch 3 moves farther, the speed request signal will gradually rise. After the user releases the button 13, under the thrust of the return spring 10, the main body 6 slides in the direction toward the front wall 1a (the longitudinal lifting direction), and the magnet 8 gradually leaves the linear Hall element 9. The magnetic field acting on the linear Hall element 9 gradually weakens, thereby gradually changing the output voltage on the circuit board 5 and finally causing the power tool to be powered off by disconnecting the power switch 2 as described below. Here, the part of the circuit board 5 related to the linear Hall element 9 and its output voltage can be regarded as a part of the speed switch 3. It is understandable that the travel of the speed switch 3 can also be detected by other types of sensing elements, such as a sliding resistor, to generate a continuously variable speed request signal.

[0039] As an example, the power switch 2 of the present application is controlled by the speed switch 3, that is, the power switch 2 is linked with the speed switch 3. Specifically, the main body 6 and the power switch 2 are arranged roughly side by side. The main body 6 is formed with a lateral protrusion 16 at its end facing the rear wall 1b. On the other hand, the power switch 2 is a mechanical on-off switch, which has a push-type switch button 17 on the side facing the rear wall 1b, and the terminal 18 of the power switch 2 is directly soldered to the circuit board 5.

[0040] The push-type switch button 17 is arranged facing the transverse protrusion 16, and in the free release position of the speed switch 3, the transverse protrusion 16 presses the switch button 17, that is, the switch button 17 is in the first button position. When the user presses the speed switch 3 through the button 13, the transverse protrusion 16 moves away from the power switch 2, and the switch button 17 extends a short distance under the action of the built-in push spring until it is separated from the transverse protrusion 16 and reaches the second button position of the free state.

[0041] The power switch 2 is provided with a contact element 19 which follows the switch button 17. Figure 1 As shown, when the user does not press the button 13, the switch button 17 is pressed down by the lateral protrusion 16 and is in the first button position, and the contact element 19 keeps the two corresponding contacts in the power switch 2 disconnected, and the power switch 2 is in the disconnected state to disconnect the power tool from the power source, such as the battery. When the user presses the button 13, the main body 6 of the speed switch 3 moves toward the rear wall 1b, and the switch button 17 is released by the lateral protrusion 16 and reaches the free second button position, as shown in FIG. Figure 2 As shown, the contact element 19 is actuated to connect the two corresponding contacts, and the power switch 2 is in the on state to connect the power line between the power tool and the battery, complete the power-on of the power tool, and generate a contact signal / power-on signal that can be output by the circuit board 5 after power-on. Therefore, the power-on signal is generated before the speed request signal. During the operation of the motor of the power tool, the user's finger always presses the button 13, and the lateral protrusion 16 remains separated from the switch button 17, so that the switch button 17 remains in the second button position without being affected by the lateral protrusion 16.

[0042] When the user releases the button 13, the main body 6 of the speed switch 3 moves toward the front wall 1a, and the switch button 17 is pressed down by the lateral protrusion 16 and returns to the first button position, thereby disconnecting the power switch 2 and disconnecting the power line between the power tool and the battery. Here, the part of the circuit board 5 related to the output power-on signal can be regarded as a part of the power switch 2.

[0043] Therefore, the lateral protrusion 16 constitutes an operating portion of the power switch 2 .

[0044] When the button 13 is not pressed, the power switch 2 remains off and the electric tool is not powered, thereby avoiding power consumption during non-working periods.

[0045] Optionally, the switch assembly 100 further comprises a locking mechanism, which is configured to lock the main body 6 when the speed switch 3 and specifically the main body 6 moves at least a portion of the stroke, and the at least a portion of the stroke may correspond to the magnet 8 being close to the linear Hall element 9. For example, the locking mechanism comprises a slot 23 formed on the outside of the main body 6 and a locking plate (not shown) formed on the inside of the housing 1, and when the main body 6 moves at least a portion of the stroke, the locking plate is pushed into the slot 23 by, for example, a spring associated therewith, to lock the main body 6 and thus the speed switch 3 relative to the housing 1. The locking mechanism can be unlocked by the user. It is understood that the locking mechanism consisting of the slot 23 and the locking plate is only schematic, and the purpose of locking the speed switch 3 at least a portion of the stroke can be achieved by various other types of locking mechanisms, thereby, even if the user releases the button 13, the speed switch 3 will not move.

[0046] In addition, other feasible forms may be adopted to implement the switch assembly in this article. For example, the power switch and the speed switch may not be linked, but a separate button may be specially provided for the power switch. In addition or alternatively, each of a plurality of buttons may be used to turn on the power switch 2. For example, the plurality of buttons include buttons on the user interaction interface or buttons with electronic switching functions. Optionally, the speed switch 3 may also be designed to be suitable for being pushed, pulled, or manipulated by the user.

[0047] The power tool that can use the switch assembly in this article is configured as a cordless power tool, that is, the power source of the power tool is a removable battery. Such power tools include, but are not limited to: angle grinders, where the angle grinder can be placed in a locked state (also referred to as lock on) by the locking mechanism mentioned above, and the speed switch 3 is not used to adjust the speed of the angle grinder (to be described in detail below); electric hammers, screwdrivers, etc., which do not have a locking mechanism and can be adjusted by the speed switch 3; circular saws, etc., which also do not have a locking mechanism and cannot be adjusted by the speed switch 3, and are high-risk tools.

[0048] These electric tools can all achieve the power-off restart protection function through the switch assembly in this article to reduce the danger caused by accidental starting of the electric tools.

[0049] To this end, in a feasible implementation of the present application, a control unit 20 for triggering the power-off restart protection function is provided for the switch assembly as a replacement for the power-off restart protection circuit mentioned in the background technology. The control unit 20 can be integrated into the main control board (e.g., MCU) of the power tool as a functional module of the main control board.

[0050] Reference Figure 3, the control unit 20 can receive the speed request signal from the speed switch 3 at any time. Moreover, the control unit 20 can send a control signal to the power tool, that is, its motor 27, at any time as needed, and the control signal is related to the start, rotation speed, stop, etc. of the motor 27. In addition, for non-high-risk power tools that are not required by regulations, after the power-off restart protection function is triggered, the control unit 20 can send a prompt signal to the alarm unit 25 to control the alarm unit 25 to prompt the user that the power-off restart protection has been triggered.

[0051] For an angle grinder in normal use, when the user presses the button 13 so that the power switch 2 is just turned on, the power tool is powered on, but the motor of the angle grinder will not run. Only when the user continues to press the button 13 so that the speed switch 3 moves at least a portion of the stroke, so that the speed request signal continuously rises to a value greater than or equal to a threshold based on the stroke, the motor of the angle grinder will run at a preset speed, that is, at least partially based on the speed request signal greater than or equal to the threshold, the motor of the angle grinder runs at the preset speed. When the speed request signal is lower than the threshold, the motor of the angle grinder will not run. The threshold may be less than the maximum speed request signal.

[0052] In addition, as described above, for an angle grinder or other electric tools with a locking mechanism, when the speed switch 3 moves at least a portion of the stroke, the locking mechanism locks the speed switch 3 so that the electric tool is in a locked state, so that even if the user releases the button 13, the motor of the electric tool continues to run at a preset speed, thereby eliminating fatigue caused by the user constantly pressing the button 13. However, an event that may occur is that the motor suddenly stops due to various faults (for example, overcurrent), and the user removes the battery from the electric tool for the purpose of maintenance and then reinstalls it without unlocking the locking mechanism to return the speed switch 3 to the free release position to disconnect the power switch 2. In this event, if the motor directly restarts, it may cause harm to the user.

[0053] For this purpose, refer to Figure 4 The control unit 20 is configured to perform the following operations within a preset period of time after the power tool is powered on again after being powered off:

[0054] Step S11. Receive / detect a speed request signal from the speed switch 3;

[0055] Step S12: Determine whether the speed request signal is greater than or equal to a threshold;

[0056] Step S13. If yes, the motor is prohibited from running, that is, the power-off restart protection function is triggered; and

[0057] Step S14: If not, the power-off restart protection function is not triggered.

[0058] First, the control unit 20 can only perform operations when the power tool is powered on, that is, when the control unit 20 performs operations, the battery has been normally placed in the power tool and the power switch 2 has been turned on. The control unit 20 cannot determine whether the power switch 2 is turned on before the battery is normally placed in the power tool based on the power-on signal generated by the power switch 2. Therefore, in step S11, the control unit 20 does not need to receive the power-on signal from the power switch 2, but only receives the speed request signal from the speed switch 3.

[0059] In steps S12-S14, the threshold value can be determined based on the position of the speed switch 3 when it is locked by the locking mechanism, and the position is reflected by the speed request signal sent when the speed switch 3 moves the at least part of the stroke. If the speed request signal generated by the speed switch 3 received within the preset period is greater than the threshold value, it means that the user did not unlock the locking mechanism to disconnect the power switch 2 before reinstalling the battery, that is, the power switch 2 is turned on before the battery is normally placed in the power tool, and the motor should be prohibited from running. If the speed request signal generated by the speed switch 3 received within the preset period is less than the threshold value, it means that the user normally presses the speed switch 3 after reinstalling the battery and thus turns on the power switch 2. In this case, the power-off restart protection function may not be triggered, that is, the control unit 20 can also control the motor to run at a preset speed based on the speed request signal greater than or equal to the threshold value received after the preset period. Therefore, compared with the time when the user normally presses the button 13 until the speed switch 3 is locked by the locking mechanism, the preset period is significantly shorter.

[0060] For electric hammers, screwdrivers, and even circular saws in normal use, they do not have a locking mechanism. When the user presses the button 13 to turn on the power switch 2, the electric tool is powered on, but the motor of the electric tool does not run. When the user continues to press the button 13 to make the speed switch 3 generate a speed request signal based on the stroke, the motor of the electric tool can run at the speed requested by the speed request signal, so that the user can adjust the speed of the electric tool by pressing the button 13. When the user releases the button 13, the speed switch 3 will return to the free release position, and the electric tool will be powered off.

[0061] What may happen is that, in order to avoid pressing the button 13 continuously, the user uses a cable tie or other external tool to bind the button 13 in the half-pressed position. As a result, the speed switch 3 is always at a certain point in the middle of the stroke and continues to generate a constant speed request signal, so that the motor continues to run at the speed requested by the constant speed request signal. At this time, the motor suddenly stops due to various faults (for example, overcurrent), and the user removes the battery from the power tool and reinstalls it for the purpose of maintenance without untying the cable tie or removing other external tools to return the speed switch 3 to the free release position and thus disconnect the power switch 2. If the motor directly restarts in such an event, it may cause injury to the user.

[0062] For this purpose, refer to Figure 5 The control unit 20 is configured to perform the following operations within a preset period of time after the power tool is powered on again after being powered off:

[0063] Step S21. receiving only a speed request signal from the speed switch 3 at at least two time points;

[0064] Step S22. Determine whether the change of the speed request signal received at the at least two time points is greater than or equal to a threshold;

[0065] Step S23. If yes, control the motor of the electric tool to run at the speed requested by the speed request signal received at the last time point of the at least two time points, that is, control the motor to run normally;

[0066] Step S24: If not, the motor is prohibited from running, that is, the power-off restart protection function is triggered.

[0067] In step S21, the control unit 20 may not receive a power-on signal from the power switch 2, but only receive a speed request signal from the speed switch 3. In steps S22-S24, it can be effectively determined whether the user is consciously manipulating the speed switch 3 while removing the battery from the power tool and then reinstalling it. If the speed request signal received by the control unit 20 at the at least two time points is greater than or equal to a threshold, it is considered that the user is consciously manipulating the speed switch 3 while controlling the power tool while removing the battery from the power tool and then reinstalling it. At this time, the control unit 20 can control the motor to run at the speed requested by the speed request signal received at the last time point of the at least two time points. If the speed request signal received by the control unit 20 at the at least two time points is less than a threshold, it is considered that the speed switch 3 is only bound by a cable tie or other external tools. At this time, the control unit 20 prohibits the motor from running to prevent accidents. It can be understood that prohibiting the operation of the motor is achieved by controlling a switch specifically used for the motor. In this article, the control unit 20 can also determine whether to trigger the power-off and restart protection function in the following events: for the purpose of energy saving, the power tool will automatically cut off the power after its motor stops running for a period of time, that is, the power switch will be automatically disconnected, and the user can press any one of the multiple buttons on the power tool to reconnect the power switch to power on the power tool again. The multiple buttons include buttons specially equipped for the power switch, buttons on the user interaction interface, or buttons with electronic commutation function. In order to prevent accidents in such events, the control unit 20 is also required to perform the above operations within a preset period of time since the power tool is powered off and then powered on again to determine whether the power-off and restart protection is triggered.

[0068] Further, step S21 includes receiving / detecting only the speed request signal from the speed switch 3 at at least three time points.

[0069] Further, step S22 includes determining whether the change of the speed request signal received at two adjacent time points among the at least three time points is greater than or equal to the threshold. Additionally, it can be further determined whether the speed request signal received at the at least three time points is in a state of gradually increasing over time.

[0070] Further, in step S23, if yes (that is, a change in the speed request signals received at two adjacent time points among the at least three time points is greater than or equal to the threshold; and additionally, whether the speed request signals received at the at least three time points are in a state of gradually increasing over time), then the motor of the power tool is controlled to run at the speed requested by the speed request signal received at the last time point among the at least three time points, that is, the motor is controlled to operate normally.

[0071] Further, in step S24, if not, the motor is prohibited from running, that is, the power-off restart protection function is triggered.

[0072] In addition, the control unit 20 can, for example, repeatedly collect the speed at which the user normally presses the speed switch 3 by means of an acceleration sensor / speed sensor installed at a suitable position of the speed switch 3, and calculate the average time required for the user to press the speed switch 3 from the free release position to at least a part of the stroke based on such speed, thereby determining the reasonable duration of the preset period and / or the interval between the at least three time points. Generally speaking, the duration of the preset period is as short as possible to ensure the timely implementation of the power-off restart protection function. The interval between the at least three time points can also be arbitrarily selected as needed. For example, the first time point of the at least three time points can be the starting time point of the preset period, the last time point can be the final time point of the preset period, and the time point between the first time point and the last time point can be one or more time points in the middle of the preset period. However, this selection is not necessary because the interval between the at least three time points can be included in the preset period.

[0073] If the speed request signal received by the control unit 20 at the at least three time points is in a state of gradually increasing over time, it is considered that the user can fully control the power tool and consciously manipulates the speed switch 3 while removing the battery from the power tool and then reinstalling it. At this time, the control unit 20 can control the motor to run at the speed requested by the speed request signal received at the last time point of the at least three time points. If the speed request signal received by the control unit 20 at the at least three time points is in a state of disorderly fluctuation or rapid decrease, it can be considered that the user is just unconsciously pressing the speed switch 3, or if the speed request signal received by the control unit 20 at the at least three time points is in a state of remaining unchanged, it is considered that the speed switch 3 is just bound by a cable tie or other external tools. At this time, the control unit 20 prohibits the motor from running to prevent accidents.

[0074] Optionally, in order to remove interference (ie, white noise) in the speed request signal, the control unit 20 may filter the speed request signal by means of a filtering algorithm / filter, for example, process, convert and / or modify the speed request signal, and using the filtered speed request signal may avoid misjudgment.

[0075] Optionally, return to Figure 3, an additional hardware circuit for the speed switch 3, such as a filter circuit 28, such as an RC filter circuit or other types of filter circuits, may be added to filter the speed request signal from the speed switch 3 to increase the reliability of the speed request signal. At the same time, the RC filter circuit may also delay the speed request signal to a certain extent, reducing the sensitivity of the electric tool to the speed switch 3 during the period of powering on again after power failure.

[0076] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are only for illustration and not for limiting the scope of the present application. It should be understood by those skilled in the art that the above embodiments may be modified and combined without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A switch assembly (100) for an electric tool, characterized in that: The switch assembly (100) comprises: a speed switch (3) configured to generate a speed request signal; and A control unit (20) is configured to perform the following operations within a preset period of time after the electric tool is powered on again after being powered off: only receiving the speed request signal from the speed switch (3); Determining that the speed request signal is greater than or equal to a threshold; and The motor of the power tool is prohibited from operating.

2. The switch assembly (100) for an electric tool according to claim 1, characterized in that: The speed switch (3) is configured to be pressed by a user to move a certain stroke, and the speed request signal changes continuously based on the stroke.

3. The switch assembly (100) for an electric tool according to claim 2, characterized in that: The switch assembly (100) further comprises: a locking mechanism configured to lock the speed switch (3) when the speed switch (3) moves at least a portion of the travel.

4. The switch assembly (100) for an electric tool according to claim 3, characterized in that: The threshold is determined based on the at least a portion of the trip.

5. A switch assembly (100) for an electric tool, characterized in that: The switch assembly (100) comprises: a speed switch (3) configured to generate a speed request signal; and A control unit (20) is configured to perform the following operations within a preset period of time after the electric tool is powered on again after being powered off: receiving only the speed request signal from the speed switch (3) at at least two time points; and At least based on the fact that the change of the speed request signal received at the at least two time points is greater than or equal to a threshold, the motor of the power tool is controlled to run at the speed requested by the speed request signal received at the last time point of the at least two time points.

6. The switch assembly (100) for an electric tool according to claim 5, characterized in that: Receiving only the speed request signal from the speed switch (3) at at least two time points includes: receiving only the speed request signal from the speed switch (3) at at least three time points; and At least based on the fact that the change of the speed request signal received at the at least two time points is greater than or equal to a threshold, controlling the motor of the power tool to run at the speed requested by the speed request signal received at the last time point among the at least two time points includes: based on the fact that the change of the speed request signal received at two adjacent time points among the at least three time points is greater than or equal to the threshold, controlling the motor of the power tool to run at the speed requested by the speed request signal received at the last time point among the at least three time points.

7. The switch assembly (100) for an electric tool according to claim 5, characterized in that: Receiving only the speed request signal from the speed switch (3) at at least two time points includes: receiving only the speed request signal from the speed switch (3) at at least three time points; and At least based on the fact that a change in the speed request signal received at the at least two time points is greater than or equal to a threshold, controlling the motor of the power tool to run at the speed requested by the speed request signal received at the last time point among the at least two time points includes: based on the fact that a change in the speed request signal received at two adjacent time points among the at least three time points is greater than or equal to the threshold, and based on whether the speed request signal received at the at least three time points is in a state of gradually increasing over time, controlling the motor of the power tool to run at the speed requested by the speed request signal received at the last time point among the at least three time points.

8. The switch assembly (100) for an electric tool according to claims 1-7, characterized in that: The switch assembly (100) further comprises: a power switch (2) configured to switch the power of the electric tool on and off so as to power on or off the electric tool.

9. The switch assembly (100) for an electric tool according to any one of claims 1 to 7, characterized in that: The control unit (20) is further configured to filter the speed request signal by means of a filtering algorithm.

10. The switch assembly (100) for an electric tool according to any one of claims 1 to 7, characterized in that: The switch assembly (100) further comprises a filter circuit configured to filter the speed request signal.

11. An electric tool, comprising the switch assembly (100) for an electric tool according to any one of claims 1 to 10.

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