Electric tool and electric tool control method

Abstract

An electric tool includes a control module, a speed regulation module and a switching circuit connected to the control module, and a motor connected to the switching circuit. The control module receives a speed regulation signal input by the speed regulation module and outputs a corresponding duty cycle signal to control the duty cycle of the switching circuit to control the speed of the motor. The control module detects and determines whether the speed regulation signal input by the speed regulation module is in an abnormal state. When the speed regulation signal is in an abnormal state, the control module controls the motor to operate at a predetermined speed. The present invention also provides a control method applied to the electric tool. When the speed regulation module is abnormal or damaged and the output speed regulation signal is unstable, the electric tool can still be used normally and will not stall.

Description

Technical field

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

[0002] Power tools are widely used in various industries. In order to meet the needs of users, most power tools are equipped with a speed regulation function. Users can control the speed of the power tool according to the application or their own habits. Generally, the speed regulation signal is transmitted to the controller through the speed regulation switch. The controller outputs a predetermined duty cycle signal to the switching circuit according to the control signal, thereby controlling the speed of the motor. However, when the speed regulation switch reaches the end of its service life or is damaged, it may not be able to correctly transmit the speed regulation signal to the controller, which may cause the motor to be unable to regulate according to the normal set speed, causing the tool to stall and affecting the normal use of the user.

[0003] In view of this, it is indeed necessary to provide an improved electric tool to overcome the defects of the prior art. [Summary of the invention]

[0004] In view of the deficiencies in the prior art, an object of the present invention is to provide an electric tool with a speed regulating module, which can continue to be used normally when an abnormality occurs in the speed regulating module.

[0005] The technical solution adopted by the present invention to solve the existing technical problems is: the electric tool includes a control module, a speed regulation module and a switching circuit connected to the control module, and a motor connected to the switching circuit. The control module receives the speed regulation signal input by the speed regulation module and outputs a corresponding duty cycle signal to control the duty cycle of the switching circuit to control the speed of the motor. The control module detects whether the speed regulation signal input by the speed regulation module is in an abnormal state. When the speed regulation signal is in an abnormal state, the control module controls the motor to operate at a predetermined speed.

[0006] Preferably, the speed control module includes a potentiometer and a speed control switch for adjusting the output voltage of the potentiometer. The speed control switch generates a stroke, the potentiometer outputs a continuous voltage signal, the potentiometer is connected to the control module, and the speed control signal received by the control module is the voltage signal output by the potentiometer.

[0007] Preferably, the control module receives one continuous speed control signal as one operation of the speed control switch. When the control module detects that the number of operations of the speed control switch is greater than or equal to the rated number of uses of the speed control switch, it determines that the speed control signal is in an abnormal state and controls the motor to operate at a predetermined speed.

[0008] Preferably, the rated number of uses is 50,000 to 100,000 times.

[0009] Preferably, the electric tool further comprises a reset button, which is connected to the control module and is used to control the number of operations to be reset to zero.

[0010] Preferably, the control module is provided with a predetermined voltage value. When the control module receives a continuous voltage signal and detects that a voltage jump exceeding the predetermined voltage value occurs more than three times within a continuous voltage signal, the control module determines that the speed regulation signal is in an abnormal state and controls the motor to operate at a predetermined speed.

[0011] Preferably, when the speed regulation signal is in an abnormal state, the control module controls the motor to enter soft start and operate at a predetermined speed.

[0012] Preferably, the control module sets the predetermined speed to the maximum speed of the motor.

[0013] Preferably, the potentiometer is a carbon film strip potentiometer.

[0014] In order to solve the problems existing in the prior art, the present invention also provides a control method for an electric tool, wherein the electric tool includes a control module, a speed regulation module and a switching circuit connected to the control module, and a motor connected to the switching circuit. The control module receives a speed regulation signal input by the speed regulation module and outputs a corresponding duty cycle signal to control the duty cycle of the switching circuit to control the speed of the motor. The control method for the electric tool includes the following steps: detecting and determining whether the speed regulation signal input by the speed regulation module is in an abnormal state; if so, controlling the motor to operate at a predetermined speed; otherwise, controlling the electric tool to operate normally.

[0015] Compared with the prior art, the present invention has the following beneficial effects: the control module detects that the speed regulation signal input by the speed regulation module is abnormal, ignores the speed regulation signal, and directly controls the motor to operate at a predetermined speed. Thus, when the speed regulation module is abnormal or damaged and the output speed regulation signal is unstable, the power tool can still be used normally without stalling.

Brief Description of the Drawings

[0016] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings:

[0017] Figure 1 It is a schematic diagram of the circuit structure of the present invention;

[0018] Figure 2 It is a schematic flow chart of a first embodiment of the present invention;

[0019] Figure 3 It is a schematic flow chart of a second embodiment of the present invention;

[0020] Figure 4 is a curve diagram showing the relationship between the switch stroke and the voltage division signal when the speed control module is abnormal in the second embodiment of the present invention;

[0021] Figure 5 This is a curve diagram showing the relationship between the speed control switch stroke and the voltage division signal when the speed control module is normal.

[0022] The meaning of the reference numerals in the figures:

[0023] 100, power tool 10, MCU controller 11, voltage detection circuit 12, speed control module 20, switch circuit 21, current detection circuit 30, motor 31, speed detection module 40, transformer module 200, battery pack R1, voltage divider resistor R2, voltage divider resistor [Specific implementation method]

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0025] like Figure 1 、 Figure 2 The figure shows an electric tool 100 involved in the first embodiment of the present invention, wherein the electric tool 100 includes a control module, a speed regulation module 12 connected to the control module and a switching circuit 20, and a motor 30 connected to the switching circuit 20. In this embodiment, the electric tool 100 is connected to a battery pack 200 and powered by the battery pack 200. The motor 30 adopts a DC brushless motor. The control module includes an MCU controller 10. The electric tool 100 also includes a transformer module 40. The input end of the transformer module 40 is connected to the positive pole of the battery pack 200, and the output end is connected to the MCU controller 10 and the speed regulation module 12 to power the MCU controller 10 and the speed regulation module 12; the MCU controller 10 receives the speed regulation signal input by the speed regulation module 12, and outputs a corresponding duty cycle signal to control the duty cycle of the switching circuit 20 to control the speed of the motor 30.

[0026] The speed control module 12 includes a potentiometer and a speed control switch for adjusting the output voltage of the potentiometer. The potentiometer includes two fixed ends and a sliding end. One end of the fixed end of the potentiometer is connected to the output end of the transformer module 40, and the other end is grounded. The sliding end of the potentiometer is connected to the speed control switch and outputs a corresponding voltage signal to the MCU controller 10 according to the stroke of the speed control switch. The speed control signal is the voltage signal; the switching circuit 20 includes a MOSFET connected to the MCU controller 10 and controlled to be turned on and off by the MCU controller. After receiving the voltage signal, the MCU controller 10 outputs a corresponding duty cycle signal to control the duty cycle of the switching circuit 20, thereby controlling the speed of the motor 30.

[0027] The MCU controller detects whether the speed control signal input by the speed control module 12 is in an abnormal state. When the speed control signal is in an abnormal state, the MCU controller 10 controls the motor 30 to operate at a predetermined speed; the MCU controller 10 receives a continuous voltage signal as one operation of the speed control switch. When the MCU controller 10 detects that the number of operations of the speed control switch is greater than or equal to the rated number of uses of the speed control switch, it determines that the voltage signal is in an abnormal state. The MCU controller 10 controls the motor 30 to enter soft start and operate at a predetermined speed. In this embodiment, the MCU controller 10 sets the predetermined speed to the maximum speed of the motor 30. When the MCU controller 10 detects that the number of operations of the speed control switch is less than the rated number of uses of the speed control switch, it determines that the voltage signal is in a normal state and controls the power tool 100 to work normally.

[0028] When the MCU controller 10 detects that the number of operations of the speed control module 12 is greater than or equal to the rated number of uses of the speed control switch, it determines that the voltage signal is abnormal, ignores the voltage signal, and directly controls the motor 30 to operate at a predetermined speed. As a result, after the speed control module 12 reaches the end of its service life, the power tool 100 can still be used normally without stalling.

[0029] It is further configured that the MCU controller 10 is connected to a voltage detection circuit 11 for detecting the voltage of the battery pack 200, a current detection circuit 21 for detecting the current of the motor 30, and a speed detection module 31 for detecting the speed of the motor 30. The voltage detection circuit 11 includes voltage-dividing resistors R1 and R2 connected in series, the voltage-dividing resistor R1 is connected to the positive pole of the battery pack 200, the voltage-dividing resistor R2 is grounded, and one end of the voltage-dividing resistors R1 and R2 connected in series is connected to the MCU controller 10; the potentiometer is a carbon film potentiometer, and the rated number of uses is set to 50,000 to 100,000 times; the power tool 100 also includes a reset button (not shown), which is connected to the MCU controller 10 to control the number of operations to be reset to zero. After replacing the speed regulation module 12 of the power tool 100, the reset button can be used to reset the number of operations to zero, thereby preventing the MCU controller 10 from continuing to control the operation of the power tool 100 based on the original number of uses of the speed regulation module 12.

[0030] The first embodiment of the present invention also provides a control method for an electric tool, wherein the electric tool 100 includes a speed regulation module 12, a control module, a switching circuit 20 and a motor 30. The control module receives a speed regulation signal input by the speed regulation module 12, and outputs a corresponding duty cycle signal to control the duty cycle of the switching circuit 20 to control the speed of the motor 30. The control method of the electric tool 100 includes the following steps: detecting and determining whether the speed regulation signal input by the speed regulation module 12 is in an abnormal state; if so, controlling the motor 30 to operate at a predetermined speed; otherwise, controlling the electric tool 100 to operate normally.

[0031] The second implementation method:

[0032] Please refer to Figure 5 The figure is a relationship diagram between the voltage signal and the speed switch stroke when the speed control module 12 is in normal use. The voltage signal increases with the increase of the speed control switch stroke. However, when an abnormality occurs in the speed control module 12, for example, when the carbon film strip of the carbon film potentiometer is worn, the resistance value of the carbon film potentiometer cannot be correctly changed according to the speed control switch stroke, and the carbon film potentiometer cannot output the voltage signal correctly according to the speed control switch stroke, resulting in the following abnormality: Figure 4 The voltage signal shown in the figure generates a downward spike, and the voltage signal experiences a voltage jump. The MCU controller 10 detects the wrong voltage signal, and the power tool 100 cannot work normally according to the user's operation of the speed control switch.

[0033] like Figure 1 、 Figure 3 、 Figure 4The figure shows an electric tool 100 involved in the second embodiment of the present invention, which differs from the first embodiment in that: the electric tool 100 does not need to be provided with the reset button, and the MCU controller 10 is provided with a predetermined voltage value. The MCU controller 10 receives a continuous voltage signal and detects that a voltage jump exceeding the predetermined voltage value occurs three or more times in the continuous voltage signal. The MCU controller 10 determines that the voltage signal is in an abnormal state and controls the motor 30 to enter soft start and operate at a predetermined speed. In this embodiment, the transformer module 40 outputs a +5V voltage, one fixed end of the potentiometer is connected to the +5V voltage, and the other fixed end is grounded. The MCU controller 10 sets the predetermined voltage value to 2V. The MCU controller 10 receives a continuous voltage signal and detects that a voltage jump exceeding 2V occurs three times in the continuous voltage signal. The MCU controller 10 controls the motor 30 to enter soft start and operate at a predetermined speed. In this embodiment, the MCU controller 10 sets the predetermined speed to the maximum speed of the motor 30.

[0034] When the MCU controller 10 detects that the voltage signal has three voltage jumps of more than 2V within a continuous voltage signal, it determines that the voltage signal is abnormal, ignores the voltage signal, and directly controls the motor 30 to operate at a predetermined speed. When the speed regulation module 12 is damaged and the output voltage signal is unstable, the power tool 100 can still be used normally and will not stall.

[0035] The present invention is not limited to the specific embodiments described above. Those skilled in the art will readily appreciate that numerous alternatives to the power tool and power tool control method of the present invention exist without departing from the principles and scope of the present invention. The scope of protection of the present invention shall be determined by the claims.

Claims

1. A power tool comprising a control module, a speed regulation module and a switch circuit connected to the control module, and a motor connected to the switch circuit, wherein the control module receives a speed regulation signal input from the speed regulation module and outputs a corresponding duty cycle signal to control the duty cycle of the switch circuit to control the speed of the motor, characterized in that: The control module detects whether the speed regulation signal input by the speed regulation module is in an abnormal state; If the control module detects that the speed regulation signal is in a normal state, the power tool is controlled to operate according to the speed regulation signal, and the speed regulation signal increases as the switch stroke of the speed regulation module increases; If the control module detects that the speed regulation signal is in an abnormal state, the motor is controlled to operate at a predetermined speed; The control module detects whether the speed regulation signal input by the speed regulation module is in an abnormal state, and the abnormal state includes at least one of the following situations: The operation times of the speed regulating module exceed the preset rated usage times; or, A voltage jump exceeding a predetermined voltage value is detected three or more times in the speed control signal continuously within a preset time period; When the speed regulation signal is in an abnormal state, the control module controls the motor to enter soft start and operate at a predetermined maximum speed.

2. The electric tool according to claim 1, wherein: The speed control module includes a potentiometer and a speed control switch for adjusting the output voltage of the potentiometer. The speed control switch generates a stroke. The potentiometer outputs a continuous voltage signal within a preset time period. The potentiometer is connected to the control module. The speed control signal received by the control module is the voltage signal output by the potentiometer.

3. The electric tool according to claim 2, wherein: The control module receives one continuous speed control signal as one operation of the speed control switch. When the control module detects that the number of operations of the speed control switch is greater than or equal to the rated number of uses of the speed control switch, it determines that the speed control signal is in an abnormal state and controls the motor to operate at a predetermined speed.

4. The electric tool according to claim 3, wherein: The rated number of uses is 50,000 to 100,000 times.

5. The electric tool according to claim 3, wherein: The electric tool further includes a reset button connected to the control module for controlling the number of operations to be reset to zero.

6. The electric tool according to claim 2, wherein: in, The control module is provided with a predetermined voltage value, and the control module detects whether the speed regulation signal input by the speed regulation module is in an abnormal state, and further comprises: The control module receives the voltage signal continuously within a preset time period, and detects that a voltage jump exceeding the predetermined voltage value occurs more than three times in the voltage signal continuously within the preset time period. The control module determines that the speed regulation signal is in an abnormal state and controls the motor to operate at a predetermined speed.

7. The electric tool according to any one of claims 2 to 5, characterized in that: The potentiometer is a carbon film strip potentiometer.

8. A method for controlling an electric tool, the electric tool comprising a control module, a speed regulation module and a switch circuit connected to the control module, and a motor connected to the switch circuit, wherein the control module receives a speed regulation signal input from the speed regulation module and outputs a corresponding duty cycle signal to control the duty cycle of the switch circuit to control the speed of the motor, characterized in that: The control method of the electric tool comprises the following steps: Detecting and determining whether the speed regulation signal input by the speed regulation module is in an abnormal state, and if so, controlling the motor to operate at a predetermined speed; otherwise, controlling the power tool to operate normally; Wherein, the determining whether the speed regulation signal input by the speed regulation module is abnormal includes: The operation times of the speed regulating module exceed the preset rated usage times; or, A voltage jump exceeding a predetermined voltage value is detected three or more times in the speed control signal continuously within a preset time period; When the speed regulation signal is in an abnormal state, the control module controls the motor to enter soft start and operate at a predetermined maximum speed.

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