CN113162485A

CN113162485A - Electric tool

Info

Publication number: CN113162485A
Application number: CN202110388307.3A
Authority: CN
Inventors: 徐宛柘; 李挺进; 刘涛; 楼健钢; 陈敏
Original assignee: Zhejiang Burley Tools Co ltd
Current assignee: Zhejiang Burley Tools Co ltd
Priority date: 2021-04-12
Filing date: 2021-04-12
Publication date: 2021-07-23

Abstract

The invention discloses an electric tool, which comprises a power supply, a switch, a motor and a control part, wherein the power supply is connected with the switch; presetting a set value, wherein when the electric tool is in a high-speed no-load state, the rotating speed of the motor is less than the set value; when the electric tool is in a load state, the control part controls the motor to increase the rotating speed and at least makes the rotating speed of the motor be larger than a preset set value. The motor is in a high-speed gear and no-load state, the rotating speed runs at a speed less than a set value, then when the motor is loaded, the rotating speed is greater than the set value, the rotating speed of the motor is fed back to the control part by the feedback program, the rotating speed of the motor is controlled by the control part to be improved to a fully-open state or run at a speed higher than the set value, at the moment, operating tools such as sawteeth of the electric tool enter a cutting state, the vibration of the whole electric tool is in a constrained state, the vibration of the whole electric tool cannot cause the increase of the vibration amplitude due to the increase of the motor speed, and the use effect and the service life of the electric tool can be effectively guaranteed.

Description

Electric tool

Technical Field

The invention relates to the technical field of electric tools, in particular to an electric tool such as a grinding machine, a drilling machine and the like.

Background

In the existing electric tools, including a series of small tool products such as a grinder, a drilling machine, a grinding machine, a stirring machine, a polishing machine, a cutting machine and an angle grinder, no matter the tool products are brush motors or brushless direct current motors, when the motors are in an idle load high-speed state, the machine body can generate very large vibration, and simultaneously, the feed of the sawteeth is easy to jump in the high-speed state, so that the sawteeth are broken or the quality of a workpiece to be machined is influenced; when the motor runs at a low speed, the machine body can be damaged by small vibration, the service life of the whole machine is influenced, and the use cost is increased.

Disclosure of Invention

The present invention is directed to overcoming the drawbacks of the prior art, and an object of the present invention is to provide an electric tool that can protect a machine body in an idle state or a low-speed state, reduce the probability of damage to the entire machine, and further reduce the use cost of a user, thereby facilitating the popularization and application of the electric tool in the market.

In order to achieve the purpose, the invention adopts the following technical scheme that the electric tool comprises a power supply, a switch, a current sampling resistor, a motor and a control part for controlling the motor; presetting a set value, wherein when the electric tool is in a high-speed no-load state, the rotating speed of the motor is in the set value; when the electric tool is in a load state, the control part controls the motor to increase the rotating speed and at least makes the rotating speed of the motor be larger than a preset set value. Through the motor under high-speed grade and unloaded state, the rotational speed moves with the speed of setting value, then when the loading, the rotational speed is greater than the setting value, the feedback procedure feeds back the rotational speed of motor to the control part, the rotational speed of control part control motor improves to full open state or moves with the speed that is higher than the setting value, operating means such as electric tool's sawtooth has entered into the cutting state this moment, make the vibrations of electric tool complete machine be in the state of retraining, the vibrations of complete machine can not lead to the increase of vibration range because the increase of motor speed, can effectually guarantee electric tool's result of use and the improvement of availability factor, strengthen user's use experience, be favorable to the popularization and the application of above-mentioned electric tool on market.

As a preferable aspect of the present invention, the electric vehicle further includes a test accessory for detecting the motor, the test accessory includes a current feedback accessory and a rotational speed test accessory, and the current feedback accessory and the rotational speed test accessory feed back the current or the rotational speed of the motor to the control unit. . The rotating speed of the motor can be timely fed back to the control part through the rotating speed testing accessory and the current feedback accessory, and the rotating speed of the motor is controlled through the control part, so that the electric tool can be effectively tested.

As a preferable aspect of the present invention, the rotational speed test accessory rotates in synchronization with the motor; the current feedback accessory judges the running state of the tool through a current feedback signal, and the change of the rotating speed of the motor is realized. The test result data of the rotating speed test accessory is more visual through the mode.

As a preferable aspect of the present invention, a rotation speed receiver for detecting a rotation speed of the motor is further provided at the motor. The rotation speed of the motor is further obtained through the rotation speed receiver, and the rotation speed of the motor is effectively detected.

As a preferable scheme of the present invention, the rotation speed receiver is a magnetic ring or a hall sensor or an encoder.

As a preferable mode of the present invention, the motor further includes a power switching element for protecting a circuit, the power switching element being electrically connected between the current feedback accessory and the motor. The power switch element can reasonably protect a control circuit of the electric tool, and the probability that the short circuit occurs in the circuit and then the service life of the electric tool is influenced is reduced.

As a preferable scheme of the present invention, the power switching element is a triac, a MOS transistor, or an IGBT module.

As a preferable aspect of the present invention, the control unit is provided with an MCU controller therein. The rotation speed of the motor is controlled by the MCU controller.

As a preferable aspect of the present invention, the power supply is a wired power supply or a wireless power supply. The user can select the power supply mode of the power supply according to the requirement, the wired power supply can continuously supply power, and the working efficiency of the electric tool is improved; the wireless power supply can be a mode of supplying a battery, so that the operation range of the electric tool is not limited, and the application range of the electric tool is further expanded.

In a preferred embodiment of the present invention, the motor is a brush motor or a brushless motor.

Compared with the prior art, the electric tool has the beneficial effects that: according to the electric tool, the rotating speed runs at a speed less than a set value in a high-speed gear and no-load state of the motor, then the rotating speed is greater than the set value in loading, the feedback program feeds the rotating speed of the motor back to the control part, the control part controls the rotating speed of the motor to be increased to a full-open state or run at a speed higher than the set value, at the moment, operating tools such as sawteeth of the electric tool enter a cutting state, vibration of the whole electric tool is in a restricted state, vibration of the whole electric tool cannot increase vibration amplitude due to increase of the speed of the motor, the use effect and the use efficiency of the electric tool can be effectively improved, the use experience of a user is enhanced, and popularization and application of the electric tool in the market are facilitated.

Drawings

FIG. 1 is a circuit diagram of a power tool in an embodiment of the invention;

FIG. 2 is a circuit diagram of a power tool in an embodiment of the invention;

FIG. 3 is a motor speed-motor current characteristic of the power tool in an embodiment of the present invention;

fig. 4 is a control flowchart of the electric power tool in the embodiment of the invention;

FIG. 5 is a circuit diagram of a power tool in an embodiment of the invention;

FIG. 6 is a circuit diagram of a power tool in an embodiment of the invention;

reference numerals: 1. a power source; 2. a switch; 3. a current sampling resistor; 4. a power switching element; 5. a motor; 6. a control unit; 7. a rotational speed receiver; 8. the rotational speed tests the attachment.

Detailed Description

The following describes embodiments of the present invention in detail with reference to the accompanying drawings.

Example (b): as shown in fig. 1 to 6, the electric power tool includes a power source 1, a switch 2, a current feedback attachment 3, a motor 5, and a control unit 6 for controlling the motor 5; presetting a set value, wherein when the electric tool is in a high-gear no-load state, the rotating speed of the motor 5 is in the set value; when the electric power tool is in a loaded state, the control unit 6 controls the motor 5 to increase the rotation speed and makes at least the rotation speed of the motor 5 greater than a preset set value. The control unit 6 is provided with a current feedback accessory 3 for current detection (load detection), and an MCU controller for controlling the motor 5 and other electric components. Through motor 5 under high-speed gear and unloaded state, the rotational speed of motor 5 moves with the speed of setting value, then when the loading, the rotational speed of motor 5 is greater than the setting value, the feedback procedure feeds back the rotational speed of motor 5 to control division 6, control division 6 control motor 5's rotational speed improves to full open state or moves with the speed that is higher than the setting value, operating means such as electric tool's sawtooth have already entered the cutting state this moment, make the vibrations of electric tool complete machine be in the state of restricting, the vibrations of complete machine can not lead to the increase of vibrations range because of the increase of motor 5 speed, can effectual assurance electric tool's result of use and the improvement of availability factor, strengthen user's use experience, be favorable to above-mentioned electric tool's popularization and application in the market.

The electric tool also comprises a test accessory for detecting the motor 5, the test accessory comprises a current feedback accessory 3 and a rotating speed test accessory 8, the current feedback accessory 3 and the rotating speed test accessory 8 feed the current or the rotating speed of the motor 5 back to the control part 6, the rotating speed of the motor 5 can be fed back to the control part 6 in time by arranging the rotating speed test accessory 8 and the current feedback accessory 3, and the rotating speed of the motor 5 is controlled by the control part 6, so that the electric tool can be effectively tested.

The rotation speed testing accessory 8 rotates synchronously with the motor 5, and the synchronous rotation mode enables the result data of the rotation speed testing accessory 8 to be more visual.

The motor 5 is further provided with a rotation speed receiver 7 for detecting the rotation speed of the motor 5, the rotation speed of the motor 5 is further obtained through the rotation speed receiver 7, and the rotation speed of the motor 5 is effectively detected, wherein the rotation speed receiver 7 is a magnetic ring or a hall sensor or an encoder. The magnetic ring, the Hall sensor and the encoder are arranged at one end of the motor 5 and used for detecting and receiving the rotating speed of the motor 5.

The electric tool further comprises a power switch element 4 for protecting a circuit, wherein the power switch element 4 is electrically connected between the current feedback accessory 3 and the motor 5, and the power switch element 4 is a bidirectional thyristor, a MOS (metal oxide semiconductor) transistor or an IGBT (insulated gate bipolar transistor) module. The power switch element 4 can reasonably protect a control circuit of the electric tool, and the probability that the service life of the electric tool is influenced by the short circuit in the circuit is reduced. At present, bidirectional thyristors are mostly adopted for alternating current voltage regulation, and the bidirectional thyristor has the advantages of small volume, light weight, high efficiency, convenience in use and the like, and has remarkable effects of improving the production efficiency, reducing the cost and the like. The MOS transistor has a tendency to gradually replace a triode in an integrated circuit by virtue of its advantages of low power consumption, stable performance, strong radiation resistance, and the like. The MOS tube has a more convenient control mode in the aspect of voltage control, and has small volume, light weight and long service life. The anti-interference ability is strong, and the power consumption is low. The power amplifier has the advantages of small encouragement power, large output power, negative temperature coefficient of output drain current, safety, firmness, high working frequency, simple bias and the like. The IGBT is an abbreviation of an Insulated Gate Bipolar Transistor (IGBT), is a device formed by compounding an MOSFET and a Bipolar Transistor, has the advantages of small driving power and high switching speed of the MOSFET device and has the advantages of reduced saturation voltage and large capacity of the Bipolar device, and the input electrode of the IGBT is the MOSFET and the output electrode of the IGBT is the PNP Transistor.

The power supply 1 is an ac power supply such as an industrial power supply, and may be a wired power supply or a wireless power supply, and the user can select a power supply mode of the power supply as needed. The wired power supply is connected to the electric tool through the cable, so that power can be continuously supplied, and the working efficiency of the electric tool is improved. The wireless power supply can be a mode of supplying a battery, so that the operation range of the electric tool is not limited, and the application range of the electric tool is further expanded.

The motor 5 is a brush motor or a brushless motor, and can be selected as desired.

The switch 2 is switched by an operator. The power switching element 4 is an example of a semiconductor element for controlling the supply of electric power to the motor 2. The current feedback accessory 3 converts the current flowing through the motor 5 into a voltage. A motor 5, a power switching element 4, and a current feedback accessory 3 are connected in series between both terminals of the power supply 1. The control unit 6 sends a signal to the gate of the power switching element 4 to control the switching of the power switching element 4 at a predetermined duty ratio, and the control unit 6 detects the current flowing through the motor 5 by feeding back the terminal voltage of the accessory 3 with the current, and various calculations in the control unit 6 are performed by the MCU controller.

As shown in fig. 3, a motor speed-motor current characteristic diagram of the electric power tool is shown. In fig. 3, the vertical axis represents the rotation speed R of the motor 5, and the horizontal axis represents the load, which is the current I flowing through the motor 5. Note that the characteristic 1 indicates a case where the duty ratio is D1 (e.g., 100%), and the characteristic 2 indicates a case where the duty ratio is D2(D2 < D1). As shown in fig. 3, if the duty ratio is constant, the lower the rotation speed R of the motor 5, the larger the current I (load) flowing through the motor 5. The region in which the current I exceeds Imax (overload protection threshold) is an overload protection range, and if the current I exceeds Imax, the control unit 6 stops the motor 5. The region where the current I is I3 or less is the constant speed control range, and the controller 6 controls the rotation speed R so as not to exceed R3.

As shown in fig. 4, a control flowchart of the electric power tool of fig. 1, 2, 5, and 6 is shown. The operator turns on the switch 2 of the electric power tool to start the work. Setting the duty cycle to D1; the control unit 6 drives the motor 5 at the duty ratio D1, detects (monitors) the current I flowing through the motor 5 by the terminal voltage of the current feedback accessory 3, and determines whether or not the current I exceeds Iset, which can be set arbitrarily in advance. If I is greater than Iset, the control section 6 starts the duty ratio adjustment mode; if I is not greater than Iset, setting the duty ratio to be greater than D1, if the duty ratio is greater than D1, controlling unit 6 starts to decrease the duty ratio, if the duty ratio is not greater than D1, controlling unit 6 does not adjust the duty ratio; then judging whether the motor 5 is in a high gear, if so, judging whether I is larger than I1, if I is larger than I1, analyzing and calculating the value of the duty ratio which is fully opened or opened to a high position through the control part 6, and outputting the duty ratio value; if not, the duty ratio value is directly output. If I is not greater than I1, control unit 6 starts to decrease the duty ratio and directly outputs the duty ratio value.

The electric tool in the embodiment is in a high-speed gear and no-load state through the motor 5, the rotating speed runs at a speed less than a set value, then when the electric tool is loaded, the rotating speed is greater than the set value, the feedback program feeds the rotating speed of the motor 5 back to the control part, the control part 6 controls the rotating speed of the motor to be increased to a fully open state or run at a speed higher than the set value, at the moment, operating tools such as sawteeth of the electric tool enter a cutting state, vibration of the whole electric tool is in a constrained state, vibration of the whole electric tool cannot increase vibration amplitude due to increase of the motor speed, the use effect and the use efficiency of the electric tool can be effectively guaranteed, use experience of a user is enhanced, and popularization and application of the electric tool in the market are facilitated.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention; thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Although the reference numerals in the figures are used more here: 1. a power source; 2. a switch; 3. a current sampling resistor; 4. a power switching element; 5. a motor; 6. a control unit; 7. a rotational speed receiver; 8. rotational speed test accessories, etc., but does not exclude the possibility of using other terms. These terms are used merely to more conveniently describe and explain the nature of the present invention; they are to be construed as being without limitation to any additional limitations that may be imposed by the spirit of the present invention.

Claims

1. Electric tool, its characterized in that: comprises a power supply (1), a switch (2), a motor (5) and a control part (6) for controlling the motor (5); presetting a set value, wherein when the electric tool is in a high-speed no-load state, the rotating speed of the motor (5) is in the set value; when the electric tool is in a load state, the control part (6) controls the motor (5) to increase the rotating speed and at least makes the rotating speed of the motor (5) be larger than a preset set value.

2. The power tool of claim 1, wherein: the motor speed testing device is characterized by further comprising a testing accessory for detecting the motor (5), wherein the testing accessory comprises a current feedback accessory (3) and a rotating speed testing accessory (8), and the current feedback accessory (3) and the rotating speed testing accessory (8) feed back the current or the rotating speed of the motor (5) to the control part (6).

3. The power tool of claim 2, wherein: the rotational speed testing accessory (8) and the motor (5) rotate synchronously; the current feedback accessory (3) judges the running state of the tool through a current feedback signal, and the change of the rotating speed of the motor (5) is realized.

4. The power tool of claim 3, wherein: and a rotating speed receiver (7) for detecting the rotating speed of the motor (5) is also arranged at the motor (5).

5. The power tool of claim 4, wherein: the rotating speed receiver (7) is a magnetic ring or a Hall sensor or an encoder.

6. The power tool of claim 5, wherein: and a power switch element (4) for protecting the circuit, wherein the power switch element (4) is electrically connected between the current feedback accessory (3) and the motor (5).

7. The power tool of claim 6, wherein: the power switch element (4) is a bidirectional thyristor or an MOS tube or an IGBT module.

8. The power tool of claim 7, wherein: an MCU controller is arranged in the control part (6).

9. The power tool of claim 8, wherein: the power supply (1) is a wired power supply or a wireless power supply.

10. The power tool of claim 9, wherein: the motor (5) is a brush motor or a brushless motor.