Electric cutting tool and its control method

Abstract

The present invention discloses an electric cutting tool, comprising: a brushless motor including a stator winding and a rotor; a power supply for supplying power to the stator winding; a cutting member driven by the brushless motor to perform reciprocating motion; a switch device for starting or stopping the brushless motor; a lighting device for illuminating a working area; after the electric tool is started, the lighting device has a flashing state and a constant-on state; a controller for controlling the lighting device to generate light changing at a preset frequency according to the demagnetization time of the motor, so that the lighting device is in the flashing state. The present invention provides an electric tool capable of precisely machining a workpiece to be operated.

Description

Technical Field

[0001] The present invention relates to a power tool, and more particularly to an electric cutting tool with a lighting device. Background Art

[0002] When using a power tool, it is usually necessary to align the power tool with the workpiece to be operated. Especially for electric cutting tools, such as a jigsaw, a circular saw, etc., in order to achieve the desired cutting effect, it is also necessary to precisely control the cutting direction, angle, and speed.

[0003] However, when the saw blade is running at a high speed during operation, for example, at a working frequency of 50 Hz, the cutting position of the saw blade will become blurred, and it is difficult for the user to observe the relative position between the saw blade and the workpiece to be operated, resulting in deviations during cutting, which is not conducive to precisely machining the workpiece to be operated. Summary of the Invention

[0004] To solve the deficiencies of the prior art, the purpose of the present invention is to provide a power tool that can precisely machine the workpiece to be operated.

[0005] To achieve the above objective, the present invention adopts the following technical solutions:

[0006] An electric cutting tool, comprising: a brushless motor including a stator winding and a rotor; a power supply for supplying power to the stator winding; a cutting member driven by the brushless motor; a switch device for starting or stopping the brushless motor; a lighting device for illuminating the working area; after the power tool is started, the lighting device has a flashing state and a constant-on state; a controller for controlling the lighting device to generate light changing at a preset frequency according to the demagnetization time of the motor, so that the lighting device is in the flashing state.

[0007] Optionally, the controller is configured to control the lighting device to be in the flashing state when the demagnetization time of the motor is less than or equal to a preset time; and control the lighting device to be in the constant-on state when the demagnetization time of the motor is greater than the preset time.

[0008] Optionally, the power tool includes: a voltage detection module for detecting the phase voltage of the motor; a voltage comparison module for comparing the phase voltage with a preset voltage to output a motor demagnetization start signal and a motor demagnetization end signal.

[0009] Optionally, the voltage comparison module outputs a motor demagnetization start signal when the phase voltage is greater than or equal to the reference voltage;

[0010] The voltage comparison module outputs a motor demagnetization end signal when the phase voltage is less than the reference voltage.

[0011] Optionally, the power tool includes one or more voltage comparison modules.

[0012] Optionally, the controller includes a timing unit;

[0013] The timing unit is connected to the voltage comparison module for obtaining the demagnetization time of the motor;

[0014] The timing unit is triggered by the motor demagnetization start signal to start timing;

[0015] The timing unit stops timing when receiving the motor demagnetization end signal.

[0016] Optionally, the preset voltage is greater than 0 and less than U E , where U E is the voltage of the power supply.

[0017] Optionally, the power tool further includes:

[0018] A speed regulation device having multiple gears, and the speed regulation device is operated by a user to output a speed regulation signal to the controller;

[0019] The controller controls the rotation speed of the motor according to the speed regulation signal.

[0020] Optionally, the preset frequency is a fixed frequency.

[0021] Optionally, the lighting device can generate light with a frequency change corresponding to the gear according to the gear.

[0022] The beneficial effect of the present invention is to provide a power tool capable of precisely processing a workpiece to be operated. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic structural diagram of an embodiment of an electric cutting tool;

[0024] Figure 2 is a schematic structural diagram of another perspective of an embodiment of an electric cutting tool;

[0025] Figure 3 is a schematic circuit diagram of an embodiment of an electric cutting tool;

[0026] Figure 4 is Figure 3 the circuit diagram of the drive circuit in the shown embodiment;

[0027] Figure 5 is a curve diagram of the correspondence between the voltages of each phase of U, V, and W and the rotor position;

[0028] Figure 6It is a schematic diagram for explaining the principle of the U-phase winding demagnetization event;

[0029] Figure 7 It is Figure 3 The circuit block diagram of the controller in the embodiment shown;

[0030] Figure 8 It is Figure 3 The output waveform diagram of the voltage comparison module in the embodiment shown when detecting the U-phase winding demagnetization event;

[0031] Figure 9 It is a schematic structural diagram of the second embodiment of the electric cutting tool;

[0032] Figure 10 It is a schematic structural diagram of another perspective of the second embodiment of the electric cutting tool;

[0033] Figure 11 It is a flowchart of the control method for the lighting device of the electric cutting tool. Detailed implementation manners

[0034] The present invention will be specifically introduced below in conjunction with the accompanying drawings and specific embodiments.

[0035] Figure 1 And Figure 2 Fig. shows an electric cutting tool 100, including: a tool housing 11, a brushless motor 12, a functional member 13, a switch device 14 and a tool mating portion 15.

[0036] The tool housing 11 forms a handle portion 111 for the user to hold and a head housing portion 112 at the front end of the handle portion 111. The handle portion 111 can be held by the user to operate the power tool. The head housing portion 112 forms a head housing space capable of accommodating the brushless motor 12 and the transmission mechanism, and the head housing portion 112 has a left side and a right side arranged oppositely as shown in the figure. The brushless motor 12 is used to convert electrical energy into power transmitted to the output shaft. Specifically, the brushless motor 12 includes a rotor, a stator and a motor shaft. The output shaft and the motor shaft are connected through a transmission mechanism to transmit the driving force of the brushless motor 12 to the output shaft. The functional member 13 is used to realize the function of the brushless motor 12. The functional member 13 is installed on the output shaft. It can be understood that different power tools have different functional members 13. For example, for an electric cutting tool, the functional member 13 is a cutting member, and the brushless motor 12 drives the cutting member to make a reciprocating motion to cut the object to be cut; in other embodiments, such as angle grinding, the functional member 13 can also be a grinding disc.

[0037] The tool housing 11 is also provided with a switch device 14 for starting or stopping the operation of the brushless motor 12. When the operation switch is triggered, the brushless motor 12 starts, and when the operation switch is released, the brushless motor 12 stops. Specifically, the switch device 14 is arranged on the head housing part 112.

[0038] In some embodiments, the tool housing 11 is further provided with a speed regulating device 18 for regulating the speed of the brushless motor 12. Specifically, the speed regulating device 18 has multiple gears, and each gear corresponds to a different speed range of the brushless motor 12. The speed regulating device 18 is operated by the user to control the speed of the brushless motor 12. In some embodiments, the speed regulating device 18 and the switch device 14 are integrally arranged.

[0039] The tool mating part 15 is used to cooperate with a power supply to access electrical energy to supply power to the power tool. In some embodiments, the power tool 100 is powered by a DC power supply. More specifically, the power tool is powered by a battery pack. It can be understood that the power supply is not limited to the scenario of using a battery pack, and it can also be powered by mains electricity or an AC power supply, in cooperation with corresponding rectification, filtering, and voltage regulation circuits, to supply power to the power tool.

[0040] The electric cutting tool 100 further includes a lighting device 16 for illuminating the working area. The lighting device 16 is installed at a position where it can directly irradiate the cutting piece. In some embodiments, the power tool includes one lighting device 16, and the lighting device 16 is located directly above the cutting piece; in other embodiments, the power tool includes at least two lighting devices 16, and the two lighting devices are a first lighting device 161 and a second lighting device 162, which are respectively located on the left and right sides of the head housing part 112 near the cutting piece, so that the user can have the illumination of the lighting device 16 no matter which side of the cutting piece they look from.

[0041] The lighting device 16 includes a lamp housing 163 and a lighting component 164. The lamp housing 163 provides a space to accommodate the lighting component 164, and the light emitted by the lighting component 164 passes through the housing and irradiates obliquely forward and downward. The lighting component 164 can be a light-emitting diode or a halogen light source, and there is no limitation here. The light-emitting part of the lighting component 164 is received inside the lamp housing 163 in a state facing forward. The cutting piece is formed with a first plane 131. In order to facilitate the user to observe the entire cutting piece, generally, the angle A formed between the orientation of the light-emitting part of the lighting component 164 and the plane where the first plane 131 of the cutting piece is located is between 10° and 65°.

[0042] In some embodiments, the first plane 131 of the cutting piece is provided with a scale to facilitate observing the cutting depth when the cutting piece is working, thereby improving the cutting accuracy.

[0043] Figure 3The block diagram 200 of the control system of an electric cutting tool according to an embodiment is shown. As Figure 3 shown, the electric cutting tool 100 further includes: a power supply sub-module 21, a switching device 14, a driving chip 22, a driving circuit 23, a controller 24, a voltage detection module 25, and a voltage comparison module 26.

[0044] The power supply sub-module 21 is used to supply power to the driving chip 22 and / or the controller 24. In some embodiments, the power supply sub-module 21 is connected to the power supply 17 to convert the power of the power supply 17 into a supply voltage adapted to the driving chip 22 and / or the controller 24 for output. For example, in order to supply power to the driving chip 22, the power supply sub-module 21 reduces the voltage from the power supply 17 to 15V to supply power to the controller 24, and reduces the voltage of the power supply 17 to 3.2V to supply power to the driving chip 22.

[0045] The switching device 14 is used to start or stop the brushless motor 12. The switching device 14 is located between the power supply sub-module 21 and the driving chip 22. In some embodiments, the switching device 14 serves as the trigger switch of the power tool and can be arranged at the position as Figure 1 shown. When the user presses the trigger switch device 14 to make the switching device 14 in the on position, the driving chip 22 and / or the controller 24 receive an electrical signal from the power supply sub-module 21, and the brushless motor 12 is powered on; when the user presses the trigger switch device 14 to the off position, the electrical connection between the driving chip 22 and / or the controller 24 and the power supply sub-module 21 is cut off, and the brushless motor 12 is powered off.

[0046] The driving chip 22 is used to control the on or off state of the electronic switches in the driving circuit 23. The driving chip 22 is connected in series between the controller 24 and the driving circuit 23, and controls the on or off state of the electronic switches in the driving circuit 23 according to the control signal from the controller 24. In some embodiments, the control signal from the controller 24 is a PWM control signal. In this embodiment, the driving chip 22 is shown as being separated from the controller 24. In other embodiments, the driving chip 22 and the controller 24 can be integrated into one unit.

[0047] The driving circuit 23 is used to drive the brushless motor 12, and the driving circuit 23 is electrically connected to the voltage conversion module. The input end of the driving circuit 23 receives the DC pulsating voltage from the power supply 17, and distributes the power of the DC pulsating voltage to each phase winding on the stator of the brushless motor 12 in a certain logical relationship under the drive of the driving signal output by the driving chip 22, so that the brushless motor 12 starts and generates continuous torque. Specifically, the driving circuit 23 includes a plurality of electronic switches. In some embodiments, the electronic switches include field effect transistors (FETs), and in other embodiments, the electronic switches include insulated gate bipolar transistors (IG-BTs), etc. Refer toFigure 4 In some embodiments, the drive circuit 23 is a three-phase bridge circuit. The drive circuit 23 includes three drive switches Q1, Q3, Q5 arranged as high-side switches and three drive switches Q2, Q4, Q6 arranged as low-side switches.

[0048] The three drive switches Q1, Q3, Q5 as high-end switches are respectively arranged between the power supply line and each phase coil of the brushless motor 12. The three switching elements Q2, Q4, Q6 as low-end switches are respectively arranged between each phase coil of the brushless motor 12 and the ground wire.

[0049] The gate terminals UH, UL, VH, VL, WH, WL of the six drive switches Q1-Q6 are electrically connected to the controller 24, and each drain or source of the drive switch is connected to the stator winding of the brushless motor 12. The drive switches Q1-Q6 change their on or off states at a certain frequency according to the control signal output by the controller 24, thereby changing the power state of the power supply 17 applied to the winding of the brushless motor 12.

[0050] The drive circuit 23 is a circuit for driving the brushless motor 12 to rotate by switching the energization state of each phase winding of the brushless motor 12 and controlling the energization current of each phase winding. The conduction sequence and time of each phase winding depend on the position of the rotor. In order to rotate the brushless motor 12, the drive circuit 23 has multiple drive states. In one drive state, a magnetic field is generated in the stator winding of the brushless motor 12. The controller 24 outputs a control signal based on different rotor positions to control the drive circuit 23 to switch the drive state so that the magnetic field generated in the stator winding rotates to drive the rotor to rotate, thereby realizing the drive of the brushless motor 12.

[0051] Taking Figure 3 the shown brushless motor 12 as an example, the brushless motor 12 includes a rotor and a stator. The stator includes a first-phase winding U, a second-phase winding V, and a third-phase winding W. These three-phase windings U, V, W form a "Y" connection, one end of which is connected to the neutral point O, and the other ends 12U, 12V, 12W are respectively led out of the brushless motor 12 as winding connection terminals and connected to the winding connection terminals provided on the brushless motor 12 (not shown in the figure). The drive circuit 23 and other peripheral circuits can be connected to the connection terminals 12U, 12V, 12W of the three-phase windings U, V, W through the winding connection terminals. In order to drive Figure 3The brushless motor 12 shown has at least six driving states. For the convenience of description, the following driving states correspond to the connected terminals, which represent the driving states. For example, the controller 24 controls the driving circuit 23 to connect the first-phase winding U to the positive power supply and the second-phase winding V to the positive or negative power supply respectively. If the first-phase winding U is connected to the positive power supply, that is, the terminal 12U of the first-phase winding is connected to the positive power supply, then this driving state is represented by UV. If the second-phase winding V is connected to the positive power supply, that is, the terminal 12V of the second-phase winding is connected to the positive power supply, then this driving state is represented by VU. The driving method represented in this way is also applicable to the delta connection scheme of the windings. In addition, the switching of the driving states can also be simply referred to as the commutation action of the brushless motor 12. Obviously, the brushless motor 12 commutes once every 60° rotation of the rotor. When the brushless motor 12 is working, the controller 24 controls the driving circuit 23 to sequentially output six driving states of UV, UW, VW, VU, WU, and WV during driving.

[0052] The voltage detection module 25 is used to detect the phase voltage of the brushless motor 12. The voltage detection module 25 detects at least the voltage of one of the three phases of the first-phase winding U, the second-phase winding V, and the third-phase winding W of the motor. In some embodiments, the voltage detection module 25 is a voltage sensor. In other embodiments, the voltage detection module 25 includes a voltage detection circuit with a voltage-dividing resistor.

[0053] As Figure 5 shown is the curve of the corresponding relationship between the phase voltage of the brushless motor 12 and the rotor position during one period, that is, when the rotor rotates 360°. In this curve, when the brushless motor 12 commutes, a demagnetization event will occur, and the time corresponding to the demagnetization event is the demagnetization time. Taking the curve of the corresponding relationship between the U-phase voltage and the rotor position as an example, when WU turns on and changes to WV turning on, the 12U terminal will have a voltage overshoot phenomenon during the energization of the WV phase, and the voltage overshoot can make the voltage value reach U M , this voltage overshoot phenomenon is the lower-bridge commutation demagnetization event; after UW turns on and changes to VW turning on, the U terminal will have a voltage undershoot phenomenon during the energization of the VW phase, and then the voltage slowly drops to zero. This voltage undershoot phenomenon is the upper-bridge commutation demagnetization event. For the V phase, when UV turns on and changes to UW turning on, the V terminal will have a lower-bridge commutation demagnetization event during the energization of the UW phase; when VU turns on and changes to WU turning on, the V terminal will have an upper-bridge commutation demagnetization event during the energization of the WU phase. For the W phase, when VW turns on and changes to VU turning on, the W terminal will have a lower-bridge commutation demagnetization event during the energization of the VU phase; when WV turns on and changes to UV turning on, the W terminal will have an upper-bridge commutation demagnetization event during the energization of the UV phase.

[0054] Specifically, the above demagnetization event is caused by inductive current continuation. AsFigure 6 , taking phase U as an example, during the actual commutation process from WU to WV, since the current in the phase U winding suddenly decreases, the self-inductance of its winding will become an electromotive force generator during the freewheeling period, and the direction of the electromotive force is opposite to the original one, and it is superimposed on the neutral point O. At this time, the potential of the U terminal is higher than the potential of the neutral point O. When the energy of the phase U winding is exhausted, the potential of the U terminal will be lower than the potential of the neutral point O at this time. This is the lower-bridge commutation demagnetization event. It can be understood that during the actual commutation process from UW to VW, since the current in the phase U winding suddenly decreases, the self-inductance of its winding will become an electromotive force generator during the freewheeling period, and the direction of the electromotive force is opposite to the original one, and it is superimposed on the neutral point O. At this time, the potential of the U terminal is lower than the potential of the neutral point O. When the energy of the phase U winding is exhausted, the potential of the U terminal will rise again at this time, thus generating a voltage undershoot phenomenon. This is the upper-bridge commutation demagnetization event. And the time duration of the demagnetization event is the demagnetization time.

[0055] To obtain the above-mentioned demagnetization time, the power tool further includes a voltage comparison module 26, and the voltage comparison module 26 is connected to the voltage detection module 25 and receives the phase voltage detected by the voltage detection module 25. In some embodiments, the voltage comparison module 26 is set as a high-level comparison unit and has a reference voltage RH. For the voltage comparison module 26, when the amplitude of the phase voltage detected by the voltage detection module 25 is higher than the reference voltage RH, the voltage comparison module 26 outputs a demagnetization start signal for the brushless motor 12. On the contrary, when the amplitude of the phase voltage detected by the voltage detection module 25 is lower than the reference voltage RH, the voltage comparison module 26 outputs a demagnetization end signal for the brushless motor 12. In some embodiments, the reference voltage RH is greater than 0 and less than U E , further, the reference voltage RH is greater than or equal to 40%U E and less than or equal to 60%U E , where U E is the voltage of the power supply 17.

[0056] Such as Figure 7As shown, taking the U-phase winding as an example, the voltage comparison module 26 is turned on in the WU driving state. When WU conduction changes to WV conduction, the voltage comparison module 26 detects the rising edge of the U-phase winding phase voltage, and thus outputs a high-level signal. When the voltage comparison module 26 detects the falling edge of the U-phase winding phase voltage, it outputs a low-level signal, and then the voltage comparison module 26 is turned off. In the next cycle, the voltage comparison module 26 is turned on again in the WU driving state. In this way, the lower-bridge commutation demagnetization event can be detected through the voltage comparison module 26. For the V-phase winding, the voltage comparison module 26 is turned on in the UV driving state. When UV conduction changes to UW conduction, the voltage comparison module 26 detects the rising edge of the V-phase winding phase voltage, and thus outputs a high-level signal. When the voltage comparison module 26 detects the falling edge of the V-phase winding phase voltage, it outputs a low-level signal, and then the voltage comparison module 26 is turned off. In the next cycle, the voltage comparison module 26 is turned on again in the UV driving state. For the W-phase winding, the voltage comparison module 26 is turned on in the VW driving state. When VW conduction changes to VU conduction, the voltage comparison module 26 detects the rising edge of the W-phase winding phase voltage, and thus outputs a high-level signal. When the voltage comparison module 26 detects the falling edge of the W-phase winding phase voltage, it outputs a low-level signal, and then the voltage comparison module 26 is turned off. In the next cycle, the voltage comparison module 26 is turned on again in the VW driving state.

[0057] In some embodiments, the voltage comparison module 26 and the controller 24 can be integrated into one unit. That is, the controller 24 is connected to the voltage detection module 25 and receives the phase voltage detected by the voltage detection module 25. Among them, the voltage detection module detects the phase voltage at regular intervals. For the controller 24, when the amplitude of the phase voltage detected by the voltage detection module 25 is higher than the reference voltage RH, the controller 24 outputs a signal for starting the demagnetization of the brushless motor 12. On the contrary, when the amplitude of the phase voltage detected by the voltage detection module 25 is lower than the reference voltage RH, the voltage comparison module 26 outputs a signal for ending the demagnetization of the brushless motor 12.

[0058] It should be noted that whether the motor is operating under load can be determined by the motor demagnetization time. When the motor runs without load, the motor demagnetization time is less than or equal to the preset time, while when the motor runs under load, the motor demagnetization time is greater than the preset time. In this way, during operation, the controller 24 determines whether the motor is operating under load based on the demagnetization time of the brushless motor 12 to control the state of the lighting device 16. After the power tool is started, the states of the lighting device 16 include a flashing state and a constant-on state. When the power tool runs without load, the controller controls the lighting device to be in the flashing state. In the flashing state, the lighting device 164 generates light that changes at a preset frequency, so that the user sees a reduced moving speed of the cutting piece, facilitating the observation of the relative position of the cutting piece and the workpiece to be operated, and improving the cutting accuracy. When the power tool operates under load, the lighting device is in the constant-on state.

[0059] Specifically, the controller 24 is connected to the voltage comparison module 26, receives the brushless motor 12 demagnetization start signal and the brushless motor 12 demagnetization end signal from the voltage comparison module 26, and obtains the demagnetization time of the brushless motor 12. The controller 24 determines whether the motor is operating under load based on the demagnetization time of the brushless motor 12. When the motor runs without load, the controller 24 controls the lighting device 16 to generate light that changes at a preset frequency, so that the lighting device 16 is in the flashing state.

[0060] When the demagnetization time of the brushless motor 12 is less than or equal to the preset time, that is, when the electric cutting tool has not started cutting the workpiece to be operated, the controller 24 controls the lighting device 16 to be in the flashing state; conversely, when the demagnetization time of the brushless motor 12 is greater than the preset time, that is, when the electric cutting tool is cutting the workpiece to be operated, the controller 24 controls the lighting device 16 to be in the constant-on state. As Figure 8 shown, the controller 24 further includes a timing unit 241 and a control unit 242.

[0061] Among them, the timing unit 241 is connected to the voltage comparison module 26 and is used to obtain the demagnetization time of the brushless motor 12. The timing unit 241 is triggered by the brushless motor 12 demagnetization start signal of the voltage comparison module 26 to start timing. The timing unit 241 stops timing when it receives the brushless motor 12 demagnetization end signal, and then sends the timing result to the control unit 242. The above timing result is the demagnetization time, that is, the time difference T1 between the rising edge and the falling edge of the output signal of the voltage comparison module. In some other embodiments, the timing unit 241 is triggered by the brushless motor 12 demagnetization start signal of the voltage comparison module 26 to obtain the demagnetization start signal time Th. The timing unit 241 receives the brushless motor 12 demagnetization end signal, obtains the demagnetization end signal time Tv, and calculates the time difference T1 between the demagnetization end signal time Tv and the demagnetization start signal time Th, so as to obtain the demagnetization time.

[0062] It can be understood that the power tool 100 may include a voltage comparison module 26 for detecting the phase voltage of any one of the phase windings in the brushless motor 12, and the demagnetization time obtained by the timing unit 241 is the demagnetization time of one of the phase windings of the brushless motor 12. As an alternative implementation, the controller 24 may include a plurality of voltage comparison modules 26, which are respectively configured to compare the phase voltage of each phase winding in the brushless motor 12 with a reference voltage RH, and then the timing unit 241 can obtain the demagnetization time of each phase winding under different driving states.

[0063] It can be understood that the power tool can also detect the upper-bridge commutation demagnetization event through the voltage comparison module 26 and the timing unit 241 to obtain the demagnetization time of the brushless motor 12. The voltage comparison module 26 can also be set as a low-level comparison unit, which will not be elaborated here.

[0064] The control unit 242 is connected to the timing unit 241, and the control unit 242 is configured to control the state of the lighting device 16 according to the demagnetization time. Specifically, when the control unit 242 receives the above time difference T1, when T1 is less than or equal to a preset time, the lighting device 16 is controlled to be in a flashing state. When T1 is greater than the preset time, the lighting device 16 is controlled to be in a constant-on state.

[0065] In this way, the controller 24 obtains the demagnetization time of the brushless motor 12 by detecting the phase voltage of the brushless motor 12, and controls the lighting device 16 to be in a flashing state or a constant-on state according to the demagnetization time of the brushless motor 12, realizing an accurate switching between the flashing state and the constant-on state of the lighting device 16. When the power tool has not yet cut the workpiece to be operated, it is convenient to observe the relative position between the cutting piece and the workpiece to be operated, avoiding deviation during cutting, enabling the power tool to precisely process the workpiece to be operated, and at the same time avoiding visual interference to the user caused by the long-term flashing of the lighting device 16.

[0066] It should be noted that different illumination frequencies of the lighting device will result in different speeds of the cutting piece visually perceived by the user. Therefore, in order to enable the cutting piece to maintain a relatively low moving speed visually at different gears of the power tool, the lighting device 16 needs to generate light with a frequency change corresponding to the gear according to different gears.

[0067] In this embodiment, the speed regulating device 18 is operated by the user to output a speed regulating signal to the controller 24. The controller 24 controls the rotational speed of the brushless motor 12 according to the speed regulating signal. At the same time, the controller 24 controls the illumination change frequency of the lighting device 164 according to the speed regulating signal, that is, the controller 24 controls the lighting device 164 to generate light with a preset frequency corresponding to the gear according to the gear selection. Such control of the lighting device 164 can be obtained by generating a pulsed output current. After receiving the pulsed current, the lighting device 164 will produce a flashing effect.

[0068] In some other embodiments, such as Figures 9 to 10 the electric circular saw shown, the electric circular saw is used for cutting metals, woods, etc., and can cut workpieces of different materials according to different saw blades specifically installed.

[0069] The electric circular saw 300 may include: a housing 31, a guard 32, a motor 33, a transmission assembly (not shown), a saw blade 34, and a base plate assembly 35.

[0070] The housing includes: a handle portion 311 and a receiving portion 312. The handle portion 311 is for a user to hold to operate the electric circular saw 300, and a receiving space for arranging the motor 33 is formed inside the receiving portion 312. The motor 33 is arranged in the receiving space formed by the receiving portion 312, and the motor 33 is used to drive the saw blade 34 to move. The transmission assembly (not shown) is used to transmit the power output by the brushless motor 12 to the saw blade 34 to drive the saw blade 34 to move, and at least part of the transmission assembly is arranged in the receiving space formed by the receiving portion 312. The saw blade 34 is arranged outside the housing 31, and saw teeth are formed on one side of the saw blade 34, and the workpiece is cut by the reciprocating movement of the saw blade 34. The guard 32 at least partially surrounds the saw blade 34 to prevent the saw blade 34 from being exposed to the outside in a non-cutting state. In some embodiments, a coupling portion (not shown in the figure) for connecting a battery pack is further formed on the housing 31, so that the battery pack supplies power to the motor 33 to drive the saw blade 34 to rotate and cut the workpiece. The base plate assembly 35 includes a base plate plane 351 in contact with the workpiece, and adjusting the angle between the base plate plane 351 and the saw blade 34 can achieve cutting the workpiece at a preset angle.

[0071] In addition, the electric circular saw 300 further includes a lighting device 36, and the lighting device 36 is installed at a position where it can directly irradiate the saw blade 34. In some embodiments, a receiving recess 321 that opens downward toward the lower direction of the guard 32 is formed inside the front end of the guard 32. The lighting device (not shown in the figure) is received in the receiving recess 321 with the light-emitting portion facing downward. The lighting device 36 is completely received in the guard and does not protrude from the guard, so as to facilitate the user to observe the position of the saw blade 34 during the working process.

[0072] In this embodiment, the frequency change of the light illumination of the lighting device 36 in the flashing state is a fixed frequency. Therefore, when the demagnetization time of the motor 33 is less than or equal to a preset time, the controller controls the lighting device 36 to flash at a preset frequency. And when the demagnetization time of the motor 33 is greater than the preset time, the controller controls the lighting device 36 to be constantly on.

[0073] Combined with Figure 11 , a control method for the lighting device of an electric cutting tool as described above includes the following steps:

[0074] S11: Obtain the phase voltage of the brushless motor 12;

[0075] In this step, the voltage detection module 25 is used to detect the phase voltage of the brushless motor 12. The voltage detection module 25 detects the phase voltage of at least one of the three-phase windings U, V, and W of the motor. In some embodiments, the voltage detection module 25 is a voltage sensor. In other embodiments, the voltage detection module 2528 includes a voltage detection circuit with a voltage-dividing resistor.

[0076] S12: Determine whether the phase voltage is greater than the reference voltage;

[0077] In this step, the voltage comparison module 26 is connected to the voltage detection module 25 and receives the phase voltage detected by the voltage detection module 25. In some embodiments, the voltage comparison module 26 is set as a high-level comparison unit with a reference voltage RH. For the voltage comparison module 26, when the amplitude of the phase voltage detected by the voltage detection module 25 is higher than the reference voltage RH, the voltage comparison module 26 outputs a signal indicating the start of demagnetization of the brushless motor 12. Conversely, when the amplitude of the phase voltage detected by the voltage detection module 25 is lower than the reference voltage RH, the voltage comparison module 26 outputs a signal indicating the end of demagnetization of the brushless motor 12.

[0078] S13: Obtain the demagnetization time of the brushless motor 12;

[0079] In this step, the timing unit 241 is connected to the voltage comparison module 26 and is used to obtain the demagnetization time of the brushless motor 12. The timing unit 241 is triggered to start timing by the signal indicating the start of demagnetization of the brushless motor 12 from the voltage comparison module 26, and the timing unit 241 stops timing when it receives the signal indicating the end of demagnetization of the brushless motor 12, and then sends the timing result to the control unit 242. The above timing result is the demagnetization time.

[0080] S14: Determine whether the demagnetization time of the brushless motor 12 is less than or equal to the preset time; if so, execute step S15; otherwise, execute step S16;

[0081] S15: Control the lighting device 16 to be in a flashing state;

[0082] In this step, the control unit 242 is connected to the timing unit 241, and the control unit 242 is configured to control the lighting device 16 to generate light that changes at a preset frequency according to the demagnetization time, so that the lighting device 16 is in a flashing state;

[0083] When the demagnetization time of the brushless motor 12 is less than or equal to the preset time, control the lighting device 16 to be in a flashing state.

[0084] In some embodiments, the control unit 242 controls the light change frequency of the lighting device 164 according to the speed regulation signal, that is, the controller 24 controls the lighting device 164 to generate light with a preset frequency corresponding to the gear. Such control of the lighting device 164 can be obtained by generating a pulsed output current. After receiving the pulsed current, the lighting device 164 will produce a flashing effect;

[0085] In other embodiments, the frequency change of the light of the lighting device 16 in the flashing state is a fixed frequency.

[0086] S16: Control the lighting device 16 to be in a constantly-on state.

[0087] In this step, when the timing result is greater than the preset time, the control unit 242 controls the lighting device 16 to be in a constantly-on state.

[0088] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any form. Any technical solutions obtained by means of equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims

1. An electric cutting tool, comprising: A brushless motor, including a stator winding and a rotor; A power supply for supplying power to the stator winding; A cutting member driven by the brushless motor to perform a cutting function; A switch device for starting or stopping the brushless motor; A lighting device for illuminating the working area; After the electric cutting tool is started, the lighting device has a flashing state and a constant-on state; A controller for controlling the lighting device to generate light with a preset frequency change according to the demagnetization time of the motor, so that the lighting device is in a flashing state.

2. The electric cutting tool according to claim 1, wherein The controller is used for Controlling the lighting device to be in the flashing state when the demagnetization time of the motor is less than or equal to a preset time; Controlling the lighting device to be in a constant-on state when the demagnetization time of the motor is greater than the preset time.

3. The electric cutting tool according to claim 1, wherein The electric cutting tool includes: A voltage detection module for detecting the phase voltage of the motor; A voltage comparison module for comparing the phase voltage with a reference voltage to output a motor demagnetization start signal and a motor demagnetization end signal.

4. The electric cutting tool according to claim 3, wherein The voltage comparison module outputs a motor demagnetization start signal when the phase voltage is greater than or equal to the reference voltage; The voltage comparison module outputs a motor demagnetization end signal when the phase voltage is less than the reference voltage.

5. The electric cutting tool according to claim 3, wherein The electric cutting tool includes one or more voltage comparison modules.

6. The electric cutting tool according to claim 4, wherein The controller includes a timing unit; The timing unit is connected to the voltage comparison module for: Obtaining the motor demagnetization start signal time Th and the motor demagnetization end signal Tv; Calculating the time difference T1 between the motor demagnetization end signal time Tv and the motor demagnetization start signal time Th.

7. The electric cutting tool according to claim 4, wherein The reference voltage is greater than 0 and less than U E , where U E is the voltage of the power supply.

8. The electric cutting tool according to claim 3, wherein The electric cutting tool further includes: A speed regulation device having multiple gears, and the speed regulation device is operated by a user to output a speed regulation signal to the controller; The controller controls the rotational speed of the motor according to the speed regulation signal.

9. The electric cutting tool according to claim 8, wherein The lighting device can generate light with a frequency change corresponding to the gear according to the gear.

10. The electric cutting tool according to claim 1, wherein The preset frequency is a fixed frequency.

11. A control method for an electric cutting tool, the electric cutting tool including a brushless motor and a lighting device, the control method including: Obtaining the phase voltage of the brushless motor; Obtaining the demagnetization time of the motor according to the phase voltage of the brushless motor; Controlling the lighting device to generate light with a preset frequency change according to the demagnetization time of the motor, so that the lighting device is in a flashing state.

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