Disclosure of Invention
The invention mainly aims to provide an automatic power-off system and an automatic power-off method for an electric tool, and aims to solve the technical problems that in the prior art, the existing automatic power-off system for the electric tool is easy to cause judgment lag or error shutdown protection due to judgment based on a current value of a motor and a rotating speed of the motor.
In order to achieve the above object, the present invention provides an automatic power-off system for an electric tool, the system is applied to an electric tool, the electric tool includes a machine body, a motor and a power supply connected with the motor are configured on the machine body, the motor is also connected with a mechanical working part, and the automatic power-off system for an electric tool includes an information acquisition module and a control module;
The power supply is respectively connected with the information acquisition module and the control module, the information acquisition module is also connected with the control module, and the control module is also connected with the motor;
the information acquisition module is used for acquiring the rotation speed of the machine body along the mechanical working part of the machine body and outputting the rotation speed to the control module;
And the control module is used for judging the state of the machine body based on the rotation speed, and disconnecting the motor from the power supply when the state of the machine body is axial rotation or tends to axial rotation.
Optionally, the information acquisition module includes: an acceleration sensor;
The acceleration sensor is used for acquiring the acceleration value of the machine body;
The control module is used for receiving the acceleration value acquired by the acceleration sensor and disconnecting the motor from the power supply when the acceleration value changes.
Optionally, the acceleration sensor is a three-axis acceleration sensor or a three-axis gyroscope;
The acceleration sensor is further used for acquiring a body acceleration value of the body, wherein the body acceleration value comprises an x-axis direction acceleration value, a y-axis direction acceleration value and a z-axis direction acceleration value;
The control module is also used for receiving the machine body acceleration value acquired by the acceleration sensor, and disconnecting the motor from the power supply if the change condition of the machine body acceleration value is that the x-axis direction acceleration value does not change, the y-axis direction acceleration value positively changes and the z-axis direction acceleration value negatively changes.
Optionally, the acceleration sensor comprises a first acceleration sensor and a second acceleration sensor, and the acceleration sensor transmission signal comprises a fuselage acceleration value;
The control module is further used for acquiring the transmission signal and the signal-to-noise ratio of the first acceleration sensor and the transmission signal and the signal-to-noise ratio of the second acceleration sensor;
The control module is further used for fusing the transmission signals of the first acceleration sensor and the transmission signals of the second acceleration sensor and obtaining the signal-to-noise ratio of the fused signals;
the control module is further used for performing power-off control by taking a sensor transmission signal with higher signal-to-noise ratio as a collection signal of the information collection module if the signal-to-noise ratio of the fused signal is smaller than a signal-to-noise ratio threshold;
and the control module is further used for performing power-off control by taking the fused signal as the acquisition signal of the information acquisition module if the signal-to-noise ratio of the fused signal is not less than the signal-to-noise ratio threshold.
Optionally, the control module includes: a driving unit and a switching unit;
The driving unit is respectively connected with the information acquisition module and the switch unit, and the switch unit is also respectively connected with the power supply and the motor;
The driving unit is used for monitoring the information read by the information acquisition module, generating a power-off signal when the information read by the information acquisition module is preset information, and sending the power-off signal to the switch unit;
And the switch unit is used for disconnecting the motor from the power supply when the power-off signal is received.
Optionally, the switch unit comprises a first resistor, a first MOS tube, a breaker, a second resistor, a capacitor and a second MOS tube;
the first end of the breaker is connected with a power supply voltage end;
The second end of the breaker is respectively connected with the motor, the first end of the first resistor and the source electrode of the first MOS tube;
The second end of the first resistor is connected with the grid electrode of the first MOS tube and the drain electrode of the second MOS tube respectively;
The drain electrode of the first MOS tube is respectively connected with the first end of the capacitor and the power supply voltage end, and the second end of the capacitor is grounded;
the grid electrode of the second MOS tube is connected with the first end of the second resistor, and the second end of the second resistor is connected with the output end of the switch unit;
And the source electrode of the second MOS tube is grounded.
Optionally, the electric tool further comprises a handheld part, and a pressure sensor is arranged on the handheld part;
the pressure sensor is connected with the control module;
The pressure sensor is used for acquiring the pressure value of the handheld part;
And the control module is also used for disconnecting the motor from the power supply when the pressure value is lower than a preset pressure value.
In addition, to achieve the above object, the present invention also proposes an automatic power-off method for an electric tool, the method being applied to the automatic power-off system for an electric tool as described above, the method comprising:
Acquiring the rotation speed of the machine body along the mechanical working part of the machine body;
and judging the state of the machine body based on the rotation speed, and disconnecting the motor from the power supply when the state of the machine body is axial rotation or tends to axial rotation.
Optionally, the information acquisition module includes: the step of acquiring the rotation speed of the machine body along the mechanical working part of the machine body specifically comprises the following steps of:
Collecting an acceleration value of the airframe;
And when the acceleration value changes, disconnecting the motor from the power supply.
Optionally, the acceleration sensor is a three-axis acceleration sensor or a three-axis gyroscope; the step of collecting the acceleration value of the airframe comprises the following steps:
Acquiring a body acceleration value of the body, wherein the body acceleration value comprises an x-axis direction acceleration value, a y-axis direction acceleration value and a z-axis direction acceleration value;
Correspondingly, when the acceleration value changes, the step of disconnecting the motor from the power supply comprises the following steps:
The control module is also used for receiving the machine body acceleration value acquired by the acceleration sensor, and disconnecting the motor from the power supply if the change condition of the machine body acceleration value is that the x-axis direction acceleration value does not change, the y-axis direction acceleration value positively changes and the z-axis direction acceleration value negatively changes.
The invention provides an automatic power-off system of an electric tool, which comprises an information acquisition module and a control module; the power supply is respectively connected with the information acquisition module and the control module, the information acquisition module is also connected with the control module, and the control module is also connected with the motor; the information acquisition module is used for acquiring the rotation speed of the machine body along the mechanical working part of the machine body and outputting the rotation speed to the control module; and the control module is used for judging the state of the machine body based on the rotation speed, and disconnecting the motor from the power supply when the state of the machine body is axial rotation or tends to axial rotation. According to the system, the rotating speed of the machine body is acquired, the state of the machine body is judged based on the rotating speed, and when the state of the machine body is axial rotation or tends to be axial rotation, the connection between the motor and the power supply is disconnected, so that the occurrence of the screwing phenomenon is accurately detected, timely and accurate protection is performed, and the purposes of stable operation and safety protection are achieved.
Detailed Description
It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that all directional indicators (such as up, down, left, right, front, and rear … …) in the embodiments of the present invention are merely used to explain the relative positional relationship, movement, etc. between the components in a particular posture (as shown in the drawings), and if the particular posture is changed, the directional indicator is changed accordingly.
Furthermore, the description of "first," "second," etc. in this disclosure is for descriptive purposes only and is not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions of the embodiments may be combined with each other, but it is necessary to base that the technical solutions can be realized by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the technical solutions should be considered that the combination does not exist and is not within the scope of protection claimed by the present invention.
As shown in fig. 1, fig. 1 is a schematic diagram of a normal operation state of the electric tool.
In the electric tool, the working mode is that the relative position of the body 91 of the electric tool is fixed by the aid of a body or other parts while the electric tool is held or held by a user, and the product function of the electric tool is realized by continuous or reciprocating motion of the mechanical movement part of the electric tool.
In general, the mechanical part of the electric tool is a power source of the electric tool through the motor 92, and drives the mechanical working part 93 to work around the axial direction. After the user holds the body, the mechanical working portion 93 performs a rotational movement, and the power tool acting object 95 is subjected to a work operation through the contact surface 94.
In a normal operation, a user can hold the holding portion 96 of the electric tool and fix the electric tool body 91, and by operating the mechanical working portion 93 to contact the working contact surface 94 and the working object 95, the mechanical working portion 93 of the electric tool is rotated by the motor 92 to generate a cutting action on the working object 95.
However, when a particularly hard material (e.g., stone, steel, etc.) suddenly comes into contact with the machine working portion 93 at the working contact surface 94, it is difficult for the head of the machine working portion 93 to effectively cut the working contact surface 94 immediately, and the machine portion is suddenly locked by the hard material, stopping the rotational movement. At this time, although an operation abnormality occurs, since the power supply of the motor 92 is continuously output in a state immediately before the abnormality, the mechanical working portion 93 still has a torsion force, and the sudden locking and stopping of the motor 92 causes the torsion force at the abnormal time to be much larger than that at the normal operation, that is, the rotation torsion force value acting on the mechanical working portion 93 suddenly rises at the abnormal time. Based on the principle of force interaction, a reaction force to the torsion direction is required at this time for the tool body 91 and the hand-held portion 96 to secure the tool body, otherwise the tool body 91 will have a torsion movement in the torsion direction.
However, the locking is sudden, rapid and uncertain, and has the characteristic of instantaneous torque increase, and sudden change, and for such complex conditions, the user is usually not very responsive, so that the situation that the user cannot hold the tool and the tool is out of hand can occur at this time. The direct consequence of the tool's removal of the hand is that the body is in impact contact with the body of the user, resulting in a large probability of injury to the user when the person is struck by the tool, a phenomenon known as hand-twisting in use of the power tool, which is very dangerous, as shown in fig. 2, with the broken line representing the body portion which is torsionally moved when the hand-twisting occurs.
The protection scheme adopted by the existing electric tool products aiming at the screwing phenomenon is based on the combination of the working current of a motor driver and the judgment of the motor rotating speed to judge the screwing condition and protect.
The specific implementation method is as follows: when the rotating speed of the motor is detected to be lower than a certain threshold value and the working current of the motor is higher than a certain threshold value, the electric tool is judged to be in an abnormal state of the screwing hand at present, and then the controller cuts off the power supply of the motor, so that the mechanical working part loses the power of continuous movement, and the effect of avoiding injury of a user caused by continuous torque output after the mechanical working part is locked is achieved.
When the scheme is used, the scheme is sensitive to judging parameters of the anti-screwing state, if the current value of the motor entering the anti-screwing protection condition is set to be higher and the rotating speed of the motor is set to be lower, the trip entering judgment is delayed, and the result that the tool hurts people when the anti-screwing protection is started already occurs; on the contrary, the condition of judging the screwing hand is too sensitive, and the wrong shutdown protection of the electric tool is possibly caused by the fact that the tool enters the anti-screwing hand protection condition by mistake when in normal work, so that bad experience is brought to a user.
For this reason, the present invention proposes an automatic power-off system for an electric tool (hereinafter referred to as the system), and referring to fig. 3, fig. 3 is a block diagram of a first embodiment of the automatic power-off system for an electric tool according to the present invention.
It should be noted that the system may be applied to an electric tool, where the electric tool may include a body, and the body may be configured with a motor and a power source connected to the motor, where the motor is further connected to a mechanical working portion.
The system may include an information acquisition module and a control module. The power supply is respectively connected with the information acquisition module and the control module, the information acquisition module is also connected with the control module, and the control module is also connected with the motor.
The information acquisition module is used for acquiring the rotation speed of the machine body along the mechanical working part of the machine body and outputting the rotation speed to the control module.
The power supply may be a module for supplying power to the electric tool and the automatic power-off system of the electric tool, and the power supply is connected to a driver of the motor, so as to provide power for the whole electric tool as a power source. The motor can work in a controlled way along with the output voltage of the motor driver, so that the mechanical working part is driven to output power.
It should be explained that the information acquisition module may be a module capable of acquiring external information or a specific device state through a sensor or the like, and the information acquisition module may acquire parameters such as a rotation speed, a torque and the like of the electric tool body along a mechanical working position thereof in real time and send the corresponding parameters to the control module, so that the control module may determine the electric tool body state according to the parameters.
It will be appreciated that when the power tool is in operation, the body of the power tool and the mechanical rotation portion are rotated by the function of the motor to provide a continuous cutting action on the contact surface. The information acquisition module is used for acquiring parameters such as the rotation speed, the torque and the like of the electric tool body along the mechanical working position of the electric tool body, so that whether the electric tool normally operates can be judged.
When the information acquisition module acquires the rotation speed of the machine body along the mechanical working part of the machine body, the speed signal can be amplified and filtered, and the processed speed signal is sent to the control module. The signal amplifying circuit and the filtering circuit may be implemented in a common manner in the prior art, which is not described in detail in this embodiment.
It should be noted that, in order to more accurately obtain the operation state of the electric tool body, the information acquisition module may include: an acceleration sensor. The acceleration sensor can acquire the acceleration value of the airframe in real time, so that the acceleration value of the airframe is sent to the control module. The control module receives the acceleration value acquired by the acceleration sensor, can judge the acceleration value, and can disconnect the connection between the motor and the power supply when the acceleration value acquired by the acceleration sensor changes, so that the electric tool is powered off in time, and the injury accident caused by the screwing phenomenon is avoided.
It will be appreciated that the acceleration values of the fuselage may include one or more of the acceleration values of the fuselage in the x-axis, the acceleration values of the fuselage in the y-axis, and the acceleration values of the fuselage in the z-axis.
It should be noted that the information acquisition module may also include a vibration sensor or the like. It will be appreciated that vibrations may be more abnormal when the machine working part is suddenly locked by a hard object than in normal operation. The vibration of the machine body of the electric tool can be detected, so that whether the electric tool is twisted or not can be judged. It should be explained that, in order to avoid that such safety protection measures may affect the normal operation of the power tool to interfere, the preset vibration threshold of the power tool may be set in advance. The determination mode of the preset vibration threshold value can be that the determination is carried out according to the working characteristics of the selected materials of the electric tool when leaving the factory, the abnormal vibration value of the electric tool in the screwing state under different working gears is tested for multiple times, and the comprehensive determination is carried out according to the test results of the multiple tests, so that the preset vibration threshold value of the electric tool under different working gears is determined.
It should be understood that the above manner of comprehensively determining the preset vibration threshold value of the electric tool under different working gears according to the test results of the multiple tests may be to take the average value of the multiple test results to determine, or may be to calculate according to the variance value, which is not limited in this embodiment.
In one implementation, the information acquisition module includes an acceleration sensor; the acceleration sensor adopts a triaxial acceleration sensor or a triaxial gyroscope.
The acceleration sensor is further used for acquiring a first acceleration value of the machine body, wherein the first acceleration value comprises an acceleration value in a y-axis direction and/or a z-axis direction;
The control module is used for receiving the first acceleration value acquired by the acceleration sensor, and disconnecting the motor from the power supply when the change times of the acceleration value in the y-axis direction and/or the z-axis direction in a preset time period exceeds a time threshold.
It can be understood that under the normal working condition, the change condition of the acceleration value of the body of the electric tool in the y-axis direction and/or the z-axis direction is a regular change, and the frequency threshold value in the preset time period can be obtained according to the first acceleration value change condition under the normal condition. If the number of times of the change of the acceleration value of the body in the y-axis direction and/or the z-axis direction in the preset time period exceeds the number of times threshold, it can be stated that the electric tool may rotate abnormally, and at the moment, the connection between the motor and the power supply can be disconnected, so that possible accidents are avoided.
Further, in order to more accurately determine a condition of disconnecting the motor from the power supply, the acceleration sensor is further configured to obtain a body acceleration value of the body, where the body acceleration value includes an x-axis direction acceleration value, a y-axis direction acceleration value, and a z-axis direction acceleration value;
The control module is also used for receiving the machine body acceleration value acquired by the acceleration sensor, and disconnecting the motor from the power supply if the change condition of the machine body acceleration value is that the x-axis direction acceleration value does not change, the y-axis direction acceleration value positively changes and the z-axis direction acceleration value negatively changes.
The body acceleration value may be obtained by a triaxial acceleration sensor or a triaxial gyroscope, and the body acceleration value includes an x-axis direction acceleration value, a y-axis direction acceleration value, and a z-axis direction acceleration value of the body. The acceleration sensor can send the body acceleration value to the control module, when the control module receives the body acceleration value acquired by the acceleration sensor, the control module can judge based on the body acceleration value, and when the change condition of the body acceleration value is that the x-axis direction acceleration value does not change, the y-axis direction acceleration value positively changes and the z-axis direction acceleration value negatively changes, the abnormal rotation of the electric tool can be indicated, and at the moment, the connection between the motor and the power supply can be disconnected, so that the possible occurrence of other conditions is avoided.
And the control module is used for judging the state of the machine body based on the rotation speed, and disconnecting the motor from the power supply when the state of the machine body is axial rotation or tends to axial rotation.
In the case of normal operation of the electric tool, the motor is used as a power source to drive the mechanical working part to rotate around the axial direction as a movement mode of operation. When the machine body is axially rotated or tends to axially rotate, the electric tool is likely to be twisted, and timely safety protection is needed.
In a specific implementation, the state of the machine body can be judged through the rotation speed, and when the state of the machine body is axial rotation or tends to be axial rotation, the connection between the motor and the power supply is disconnected.
The automatic power-off system of the electric tool provided by the embodiment is applied to the electric tool, the electric tool comprises a machine body, a motor and a power supply connected with the motor are arranged on the machine body, and the motor is also connected with a mechanical working part; the system comprises an information acquisition module and a control module; the power supply is respectively connected with the information acquisition module and the control module, the information acquisition module is also connected with the control module, and the control module is also connected with the motor; the information acquisition module is used for acquiring the rotation speed of the machine body along the mechanical working part of the machine body and outputting the rotation speed to the control module; and the control module is used for judging the state of the machine body based on the rotation speed, and disconnecting the motor from the power supply when the state of the machine body is axial rotation or tends to axial rotation. According to the system, the rotating speed of the machine body is acquired, the state of the machine body is judged based on the rotating speed, when the state of the machine body is axial rotation or tends to be axial rotation, the connection between the motor and the power supply is disconnected, and the system acquires the rotating speed of the machine body through the information acquisition module on the basis of the traditional electromechanical structure of the electric tool, so that the occurrence of the screwing phenomenon is accurately detected, timely and accurate protection is performed, and the purposes of stable operation and safety protection are achieved.
Further, in order to more accurately judge the state of the body, the acceleration sensor includes a first acceleration sensor and a second acceleration sensor, and the acceleration sensor transmission signal includes a body acceleration value.
The control module is further configured to obtain the first acceleration sensor transmission signal and the signal-to-noise ratio, and the second acceleration sensor transmission signal and the signal-to-noise ratio.
The signal-to-noise ratio refers to a ratio of the strength of the received useful signal to the strength of the received interference signal. In practical applications, in order to receive a sensor signal with a higher signal-to-noise ratio, an acceleration sensor may be configured on the outside of the body and inside the body of the electric tool, respectively, so as to measure the acceleration value of the body.
It should be explained that the two configured acceleration sensors may be the same sensor or may be different sensors, and may be selected according to the needs in practical application.
The control module is further configured to fuse the first acceleration sensor transmission signal and the second acceleration sensor transmission signal, and obtain a signal-to-noise ratio of the fused signal.
It is understood that when the transmission signal of the first acceleration sensor and the transmission signal of the second acceleration sensor are acquired, the transmission signals of the two acceleration sensors may be fused.
It should be appreciated that in general, since the noise signals in the transmission signals are typically uncorrelated, during signal fusion, some of the noise signals cancel each other out, such that the signal-to-noise ratio of the fused signal is greater than the signal-to-noise ratio of the original transmission signal. Thereby increasing the signal-to-noise ratio of the signal received by the control module.
The control module is further used for performing power-off control by taking a sensor transmission signal with higher signal-to-noise ratio as a collection signal of the information collection module if the signal-to-noise ratio of the fused signal is smaller than a signal-to-noise ratio threshold;
and the control module is further used for performing power-off control by taking the fused signal as the acquisition signal of the information acquisition module if the signal-to-noise ratio of the fused signal is not less than the signal-to-noise ratio threshold.
It should be noted that if the signal-to-noise ratio of the fused signal is smaller than the signal-to-noise ratio threshold, it may be indicated that the transmission signal with a lower signal-to-noise ratio may have a fault, and at this time, the transmission signal of the sensor with a higher signal-to-noise ratio may be used as the acquisition signal of the information acquisition module to perform power-off control. For example, the signal-to-noise ratio of the transmission signal of the first acceleration sensor is 70dB, the signal-to-noise ratio of the transmission signal of the second acceleration sensor is 80dB, and the signal-to-noise ratio of the fused signal is smaller than the signal-to-noise ratio threshold, and the transmission signal of the second acceleration sensor is selected as the acquisition signal of the information acquisition module for power-off control.
It should be appreciated that the signal-to-noise ratio of the sensor transmission signal with the high signal-to-noise ratio described above needs to be greater than the second signal-to-noise ratio threshold. It will be appreciated that the signal to noise ratio threshold is greater than the second signal to noise ratio threshold.
It should be explained that the signal-to-noise ratio threshold and the second signal-to-noise ratio threshold may be set according to the type of the selected sensor, which is not limited in this embodiment.
It can be understood that if the signal-to-noise ratio of the fused signal is not less than the signal-to-noise ratio threshold, the fused signal can be used as the acquisition signal of the information acquisition module for power-off control.
In the specific implementation, the signal to noise ratio of the fused signals is obtained by acquiring the transmission signals and the signal to noise ratio of the two acceleration sensors and fusing the acquired transmission signals; if the signal-to-noise ratio of the fused signal is smaller than the signal-to-noise ratio threshold, the signal transmitted by the sensor with higher signal-to-noise ratio is used as the acquisition signal of the information acquisition module for power-off control; and the signal-to-noise ratio of the fused signal is not smaller than the signal-to-noise ratio threshold, and the fused signal is used as the acquisition signal of the information acquisition module for power-off control. The two sensors are used for acquiring the sensor transmission signals, so that the signal to noise ratio of the transmission signals acquired by the control module is ensured to be in a higher state.
Further, in order to control a connection state between the motor and the power source, the control module includes: a driving unit and a switching unit; the driving unit is respectively connected with the information acquisition module and the switch unit, and the switch unit is also respectively connected with the power supply and the motor.
The driving unit is used for monitoring the information read by the information acquisition module, generating a power-off signal when the information read by the information acquisition module is preset information, and sending the power-off signal to the switching unit.
It should be noted that, the driving unit may monitor the information read by the information acquisition module in real time, and if the information read by the information acquisition module is preset information, then a power-off signal may be generated to disconnect the connection between the motor and the power supply.
It is understood that the above-mentioned preset information is information that can cause the driving unit to generate the power-off signal, such as the first acceleration value, the body acceleration value, the rotation speed, and the like described above.
In specific implementation, the system monitors information acquired by the information acquisition module in real time through the driving unit, and generates a power-off signal when the information read by the information acquisition module is preset information.
And the switch unit is used for disconnecting the motor from the power supply when the power-off signal is received.
It can be understood that the switch unit can receive the power-off signal sent by the driving unit and disconnect the connection between the motor and the power supply when receiving the power-off signal, so that timely and accurate protection is performed.
As shown in fig. 4, fig. 4 is a schematic circuit diagram of a switch unit of a second embodiment of the automatic power-off system for an electric tool according to the present invention.
The switch unit comprises a first resistor R1, a first MOS tube Q1, a breaker CB1, a second resistor R2, a capacitor C1 and a second MOS tube Q2;
the first end of the breaker is connected with a power supply voltage end;
The second end of the breaker is respectively connected with the motor, the first end of the first resistor and the source electrode of the first MOS tube;
The second end of the first resistor is connected with the grid electrode of the first MOS tube and the drain electrode of the second MOS tube respectively;
The drain electrode of the first MOS tube is respectively connected with the first end of the capacitor and the power supply voltage end, and the second end of the capacitor is grounded;
the grid electrode of the second MOS tube is connected with the first end of the second resistor, and the second end of the second resistor is connected with the output end of the switch unit;
And the source electrode of the second MOS tube is grounded.
It should be noted that, the outage signal through the output of the drive unit gets into the switch unit from IN, amplifies the outage signal through first MOS pipe and second MOS pipe, is connected with the motor through the OUT end, breaks off the connection of motor, switch unit and power through the circuit breaker when reaching the outage threshold value to the accident that has avoided probably appearing.
It should be noted that, for further safety protection, the electric tool further includes a hand-held portion, and a pressure sensor is disposed on the hand-held portion; the pressure sensor is connected with the control module.
The pressure sensor is used for acquiring the pressure value of the handheld part;
And the control module is also used for disconnecting the motor from the power supply when the pressure value is lower than a preset pressure value.
When the user uses the pressure sensor, the user needs to grasp the hand-held portion, and thus the pressure sensor can obtain a certain pressure. Whether the pressure value of the handheld part is higher than a preset pressure value or not can be read through the pressure sensor, and the power supply is connected with other modules (such as a motor, an information acquisition module, a control module and the like) when the read pressure value is higher than the preset pressure value, so that the electric tool can work normally. When the read pressure value is lower than the preset pressure value, the power supply and other modules are not connected, so that the danger caused by direct power failure after use and false touch when the user uses the device again is prevented.
The general control module of the embodiment comprises: a driving unit and a switching unit; the driving unit is respectively connected with the information acquisition module and the switch unit, and the switch unit is also respectively connected with the power supply and the motor; the information read by the information acquisition module is detected through the driving unit, a disconnection signal is generated when the information read by the information acquisition module is preset information, and the disconnection signal is sent to the switching unit; the switch unit disconnects the motor from the power source when receiving the power-off signal.
Based on the above embodiments, the present invention further provides an automatic power-off method (hereinafter referred to as the method) for an electric tool, and referring to fig. 5, fig. 5 is a schematic flow chart of a first embodiment of the automatic power-off method for an electric tool according to the present invention.
It should be noted that the system may be applied to an electric tool, where the electric tool may include a body, and the body may be configured with a motor and a power source connected to the motor, where the motor is further connected to a mechanical working portion.
The system may include an information acquisition module and a control module. The power supply is respectively connected with the information acquisition module and the control module, the information acquisition module is also connected with the control module, and the control module is also connected with the motor. The method comprises the following steps:
Step S10: acquiring the rotation speed of the machine body along the mechanical working part of the machine body;
The power supply may be a module for supplying power to the electric tool and the automatic power-off system of the electric tool, and the power supply is connected to a driver of the motor, so as to provide power for the whole electric tool as a power source. The motor can work in a controlled way along with the output voltage of the motor driver, so that the mechanical working part is driven to output power.
It should be explained that the information acquisition module may be a module capable of acquiring external information or a specific device state through a sensor or the like, and the information acquisition module may acquire parameters such as a rotation speed, a torque and the like of the electric tool body along a mechanical working position thereof in real time and send the corresponding parameters to the control module, so that the control module may determine the electric tool body state according to the parameters.
It will be appreciated that when the power tool is in operation, the body of the power tool and the mechanical rotation portion are rotated by the function of the motor to provide a continuous cutting action on the contact surface. The information acquisition module is used for acquiring parameters such as the rotation speed, the torque and the like of the electric tool body along the mechanical working position of the electric tool body, so that whether the electric tool normally operates can be judged.
When the information acquisition module acquires the rotation speed of the machine body along the mechanical working part of the machine body, the speed signal can be amplified and filtered, and the processed speed signal is sent to the control module. The signal amplifying circuit and the filtering circuit may be implemented in a common manner in the prior art, which is not described in detail in this embodiment.
It should be noted that, in order to more accurately obtain the operation state of the electric tool body, the information acquisition module may include: an acceleration sensor. The step of obtaining the rotation speed of the machine body along the mechanical working part of the machine body specifically comprises the following steps:
The acceleration sensor can acquire the acceleration value of the airframe in real time, so that the acceleration value of the airframe is sent to the control module. The control module receives the acceleration value acquired by the acceleration sensor, can judge the acceleration value, and can disconnect the connection between the motor and the power supply when the acceleration value acquired by the acceleration sensor changes, so that the electric tool is powered off in time, and the injury accident caused by the screwing phenomenon is avoided.
It will be appreciated that the acceleration values of the fuselage may include one or more of the acceleration values of the fuselage in the x-axis, the acceleration values of the fuselage in the y-axis, and the acceleration values of the fuselage in the z-axis.
It should be noted that the information acquisition module may also include a vibration sensor or the like. It will be appreciated that vibrations may be more abnormal when the machine working part is suddenly locked by a hard object than in normal operation. The vibration of the machine body of the electric tool can be detected, so that whether the electric tool is twisted or not can be judged. It should be explained that, in order to avoid that such safety protection measures may affect the normal operation of the power tool to interfere, the preset vibration threshold of the power tool may be set in advance. The determination mode of the preset vibration threshold value can be that the determination is carried out according to the working characteristics of the selected materials of the electric tool when leaving the factory, the abnormal vibration value of the electric tool in the screwing state under different working gears is tested for multiple times, and the comprehensive determination is carried out according to the test results of the multiple tests, so that the preset vibration threshold value of the electric tool under different working gears is determined.
It should be understood that the above manner of comprehensively determining the preset vibration threshold value of the electric tool under different working gears according to the test results of the multiple tests may be to take the average value of the multiple test results to determine, or may be to calculate according to the variance value, which is not limited in this embodiment.
In one implementation, the information acquisition module includes an acceleration sensor; the acceleration sensor adopts a triaxial acceleration sensor or a triaxial gyroscope. The step of collecting the acceleration value of the airframe specifically comprises the following steps:
The acceleration sensor acquires a first acceleration value of the machine body, wherein the first acceleration value comprises an acceleration value in a y-axis direction and/or a z-axis direction;
The control module receives the first acceleration value acquired by the acceleration sensor, and disconnects the motor from the power supply when the number of times of change of the acceleration value in the y-axis direction and/or the z-axis direction in a preset time period exceeds a time threshold.
It can be understood that under the normal working condition, the change condition of the acceleration value of the body of the electric tool in the y-axis direction and/or the z-axis direction is a regular change, and the frequency threshold value in the preset time period can be obtained according to the first acceleration value change condition under the normal condition. If the number of times of the change of the acceleration value of the body in the y-axis direction and/or the z-axis direction in the preset time period exceeds the number of times threshold, it can be stated that the electric tool may rotate abnormally, and at the moment, the connection between the motor and the power supply can be disconnected, so that possible accidents are avoided.
Further, in order to more precisely determine a condition for disconnecting the motor from the power source, the acceleration sensor acquires a body acceleration value of the body, the body acceleration value including an x-axis direction acceleration value, a y-axis direction acceleration value, and a z-axis direction acceleration value.
The control module receives the acceleration value of the machine body acquired by the acceleration sensor, and if the change condition of the acceleration value of the machine body is that the acceleration value of the x-axis direction does not change, the acceleration value of the y-axis direction changes positively, the acceleration value of the z-axis direction changes negatively, the connection between the motor and the power supply is disconnected.
The body acceleration value may be obtained by a triaxial acceleration sensor or a triaxial gyroscope, and the body acceleration value includes an x-axis direction acceleration value, a y-axis direction acceleration value, and a z-axis direction acceleration value of the body. The acceleration sensor can send the body acceleration value to the control module, when the control module receives the body acceleration value acquired by the acceleration sensor, the control module can judge based on the body acceleration value, and when the change condition of the body acceleration value is that the x-axis direction acceleration value does not change, the y-axis direction acceleration value positively changes and the z-axis direction acceleration value negatively changes, the abnormal rotation of the electric tool can be indicated, and at the moment, the connection between the motor and the power supply can be disconnected, so that the possible occurrence of other conditions is avoided.
Step S20: and judging the state of the machine body based on the rotation speed, and disconnecting the motor from the power supply when the state of the machine body is axial rotation or tends to axial rotation.
In the case of normal operation of the electric tool, the motor is used as a power source to drive the mechanical working part to rotate around the axial direction as a movement mode of operation. When the machine body is axially rotated or tends to axially rotate, the electric tool is likely to be twisted, and timely safety protection is needed.
In a specific implementation, the state of the machine body can be judged through the rotation speed, and when the state of the machine body is axial rotation or tends to be axial rotation, the connection between the motor and the power supply is disconnected.
The automatic power-off system of the electric tool provided by the embodiment is applied to the electric tool, the electric tool comprises a machine body, a motor and a power supply connected with the motor are arranged on the machine body, and the motor is also connected with a mechanical working part; the system comprises an information acquisition module and a control module; the power supply is respectively connected with the information acquisition module and the control module, the information acquisition module is also connected with the control module, and the control module is also connected with the motor; the information acquisition module acquires the rotation speed of the machine body along the mechanical working part of the machine body and outputs the rotation speed to the control module; the control module judges the state of the machine body based on the rotation speed, and when the state of the machine body is axial rotation or tends to axial rotation, the connection between the motor and the power supply is disconnected. According to the system, the rotating speed of the machine body is acquired, the state of the machine body is judged based on the rotating speed, when the state of the machine body is axial rotation or tends to be axial rotation, the connection between the motor and the power supply is disconnected, and the system acquires the rotating speed of the machine body through the information acquisition module on the basis of the traditional electromechanical structure of the electric tool, so that the occurrence of the screwing phenomenon is accurately detected, timely and accurate protection is performed, and the purposes of stable operation and safety protection are achieved.
Further, in order to more accurately judge the state of the body, the acceleration sensor includes a first acceleration sensor and a second acceleration sensor, and the acceleration sensor transmission signal includes a body acceleration value.
The control module acquires the first acceleration sensor transmission signal and the signal-to-noise ratio, and the second acceleration sensor transmission signal and the signal-to-noise ratio.
The signal-to-noise ratio refers to a ratio of the strength of the received useful signal to the strength of the received interference signal. In practical applications, in order to receive a sensor signal with a higher signal-to-noise ratio, an acceleration sensor may be configured on the outside of the body and inside the body of the electric tool, respectively, so as to measure the acceleration value of the body.
It should be explained that the two configured acceleration sensors may be the same sensor or may be different sensors, and may be selected according to the needs in practical application.
The control module fuses the first acceleration sensor transmission signal and the second acceleration sensor transmission signal, and obtains the signal-to-noise ratio of the fused signal.
It is understood that when the transmission signal of the first acceleration sensor and the transmission signal of the second acceleration sensor are acquired, the transmission signals of the two acceleration sensors may be fused.
It should be appreciated that in general, since the noise signals in the transmission signals are typically uncorrelated, during signal fusion, some of the noise signals cancel each other out, such that the signal-to-noise ratio of the fused signal is greater than the signal-to-noise ratio of the original transmission signal. Thereby increasing the signal-to-noise ratio of the signal received by the control module.
When the signal-to-noise ratio of the fused signal is smaller than a signal-to-noise ratio threshold value, the control module takes a sensor transmission signal with higher signal-to-noise ratio as an acquisition signal of the information acquisition module to perform power-off control;
and when the signal-to-noise ratio of the fused signal is not smaller than the signal-to-noise ratio threshold, the control module takes the fused signal as the acquisition signal of the information acquisition module to perform power-off control.
It should be noted that if the signal-to-noise ratio of the fused signal is smaller than the signal-to-noise ratio threshold, it may be indicated that the transmission signal with a lower signal-to-noise ratio may have a fault, and at this time, the transmission signal of the sensor with a higher signal-to-noise ratio may be used as the acquisition signal of the information acquisition module to perform power-off control. For example, the signal-to-noise ratio of the transmission signal of the first acceleration sensor is 70dB, the signal-to-noise ratio of the transmission signal of the second acceleration sensor is 80dB, and the signal-to-noise ratio of the fused signal is smaller than the signal-to-noise ratio threshold, and the transmission signal of the second acceleration sensor is selected as the acquisition signal of the information acquisition module for power-off control.
It should be appreciated that the signal-to-noise ratio of the sensor transmission signal with the high signal-to-noise ratio described above needs to be greater than the second signal-to-noise ratio threshold. It will be appreciated that the signal to noise ratio threshold is greater than the second signal to noise ratio threshold.
It should be explained that the signal-to-noise ratio threshold and the second signal-to-noise ratio threshold may be set according to the type of the selected sensor, which is not limited in this embodiment.
It can be understood that if the signal-to-noise ratio of the fused signal is not less than the signal-to-noise ratio threshold, the fused signal can be used as the acquisition signal of the information acquisition module for power-off control.
In the specific implementation, the signal to noise ratio of the fused signals is obtained by acquiring the transmission signals and the signal to noise ratio of the two acceleration sensors and fusing the acquired transmission signals; if the signal-to-noise ratio of the fused signal is smaller than the signal-to-noise ratio threshold, the signal transmitted by the sensor with higher signal-to-noise ratio is used as the acquisition signal of the information acquisition module for power-off control; and the signal-to-noise ratio of the fused signal is not smaller than the signal-to-noise ratio threshold, and the fused signal is used as the acquisition signal of the information acquisition module for power-off control. The two sensors are used for acquiring the sensor transmission signals, so that the signal to noise ratio of the transmission signals acquired by the control module is ensured to be in a higher state.
Further, in order to control a connection state between the motor and the power source, the control module includes: a driving unit and a switching unit; the driving unit is respectively connected with the information acquisition module and the switch unit, and the switch unit is also respectively connected with the power supply and the motor. The method further comprises the steps of:
the driving unit monitors the information read by the information acquisition module, generates a power-off signal when the information read by the information acquisition module is preset information, and sends the power-off signal to the switching unit.
It should be noted that, the driving unit may monitor the information read by the information acquisition module in real time, and if the information read by the information acquisition module is preset information, then a power-off signal may be generated to disconnect the connection between the motor and the power supply.
It is understood that the above-mentioned preset information is information that can cause the driving unit to generate the power-off signal, such as the first acceleration value, the body acceleration value, the rotation speed, and the like described above.
In specific implementation, the system monitors information acquired by the information acquisition module in real time through the driving unit, and generates a power-off signal when the information read by the information acquisition module is preset information.
And when the switching unit receives the power-off signal, the connection between the motor and the power supply is disconnected.
It can be understood that the switch unit can receive the power-off signal sent by the driving unit and disconnect the connection between the motor and the power supply when receiving the power-off signal, so that timely and accurate protection is performed.
As shown in fig. 4, fig. 4 is a schematic circuit diagram of a switch unit of a second embodiment of the automatic power-off system for an electric tool according to the present invention.
The switch unit comprises a first resistor R1, a first MOS tube Q1, a breaker CB1, a second resistor R2, a capacitor C1 and a second MOS tube Q2;
the first end of the breaker is connected with a power supply voltage end;
The second end of the breaker is respectively connected with the motor, the first end of the first resistor and the source electrode of the first MOS tube;
The second end of the first resistor is connected with the grid electrode of the first MOS tube and the drain electrode of the second MOS tube respectively;
The drain electrode of the first MOS tube is respectively connected with the first end of the capacitor and the power supply voltage end, and the second end of the capacitor is grounded;
the grid electrode of the second MOS tube is connected with the first end of the second resistor, and the second end of the second resistor is connected with the output end of the switch unit;
And the source electrode of the second MOS tube is grounded.
It should be noted that, the outage signal through the output of the drive unit gets into the switch unit from IN, amplifies the outage signal through first MOS pipe and second MOS pipe, is connected with the motor through the OUT end, breaks off the connection of motor, switch unit and power through the circuit breaker when reaching the outage threshold value to the accident that has avoided probably appearing.
It should be noted that, for further safety protection, the electric tool further includes a hand-held portion, and a pressure sensor is disposed on the hand-held portion; the pressure sensor is connected with the control module.
The pressure sensor acquires a pressure value of the handheld part;
and when the pressure value is lower than a preset pressure value, the control module disconnects the motor from the power supply.
When the user uses the pressure sensor, the user needs to grasp the hand-held portion, and thus the pressure sensor can obtain a certain pressure. Whether the pressure value of the handheld part is higher than a preset pressure value or not can be read through the pressure sensor, and the power supply is connected with other modules (such as a motor, an information acquisition module, a control module and the like) when the read pressure value is higher than the preset pressure value, so that the electric tool can work normally. When the read pressure value is lower than the preset pressure value, the power supply and other modules are not connected, so that the danger caused by direct power failure after use and false touch when the user uses the device again is prevented.
The general control module of the embodiment comprises: a driving unit and a switching unit; the driving unit is respectively connected with the information acquisition module and the switch unit, and the switch unit is also respectively connected with the power supply and the motor; the information read by the information acquisition module is detected through the driving unit, a disconnection signal is generated when the information read by the information acquisition module is preset information, and the disconnection signal is sent to the switching unit; the switch unit disconnects the motor from the power source when receiving the power-off signal.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or system. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or system that comprises the element.
The foregoing embodiment numbers of the present invention are merely for the purpose of description, and do not represent the advantages or disadvantages of the embodiments.
From the above description of the embodiments, it will be clear to those skilled in the art that the above-described embodiment method may be implemented by means of software plus a necessary general hardware platform, but of course may also be implemented by means of hardware, but in many cases the former is a preferred embodiment. Based on such understanding, the technical solution of the present invention may be embodied essentially or in a part contributing to the prior art in the form of a software product stored in a storage medium (e.g. read-only memory/random-access memory, magnetic disk, optical disk), comprising instructions for causing a terminal device (which may be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) to perform the method according to the embodiments of the present invention.
The foregoing description is only of the preferred embodiments of the present invention, and is not intended to limit the scope of the invention, but rather is intended to cover any equivalents of the structures or equivalent processes disclosed herein or in the alternative, which may be employed directly or indirectly in other related arts.