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CN-121984408-A - Application method of pulse mode in linear speed regulation of electric tool

CN121984408ACN 121984408 ACN121984408 ACN 121984408ACN-121984408-A

Abstract

The invention discloses an application method of a pulse mode in linear speed regulation of an electric tool, and aims to solve the problem that in the prior art, the requirements of locked-rotor avoidance, linear power output and operation hand feeling optimization cannot be met when an impact screwdriver is used for coping with locked-rotor. When the central control chip detects that the electric tool is blocked, the pulse mode is automatically started, and then the duty ratio is increased by continuously pressing the pressing switch, so that the main shaft torque is gradually increased until the critical impact torque is broken through, the impact state is entered, and the pulse mode is exited. In the pulse process, even though the instantaneous output energy is continuously increased, the average output power is lower, so that the situation of 'twisting hands' is avoided, and along with the pressing of the pressing switch, the handheld part can obviously feel the feedback of the force, and the feedback is in linear positive correlation with the pressing switch.

Inventors

  • WANG HENG
  • XU XIAO
  • XU RUI
  • TU ZHONGYANG
  • DAI XIUBO

Assignees

  • 华丽电器制造有限公司

Dates

Publication Date
20260505
Application Date
20260209

Claims (6)

  1. 1. An application method of a pulse mode in linear speed regulation of an electric tool is characterized in that the pulse mode is preset on a central control chip in the electric tool, the central control chip can enable a motor to output a pulse state through PWM (pulse width modulation) in the pulse mode, an armature can output current in the pulse state, the motor in the electric tool is enabled to start and stop intermittently at intervals to output power in a pulse characteristic mode, when the electric tool carries out load operation, the central control chip automatically starts the pulse mode when detecting that the electric tool is blocked, then the duty ratio is increased through continuously pressing a pressing switch, so that output energy of a main shaft is gradually increased until critical impact conditions are broken, and when the electric tool enters the impact state, the central control chip automatically exits the pulse mode.
  2. 2. The method of claim 1, wherein the pulse amplitude of the pulse mode is positively correlated to the pressing stroke of the pressing switch, and the larger the pressing stroke is, the higher the pulse amplitude is.
  3. 3. The method of claim 2, wherein the pulse frequency in the pulse mode is positively correlated to the pressing stroke of the pressing switch, and the greater the pressing stroke, the higher the pulse frequency.
  4. 4. The method for applying the pulse mode to the linear speed regulation of the electric tool according to claim 1 is characterized by comprising a method for judging the locked-rotor state of the electric tool, wherein when the electric tool is in a non-impact working condition and the load is low, the corresponding normal state is that the motor is low in rotating speed and low in current, when the electric tool is in the impact working condition, the normal load is improved compared with the non-impact working condition, the corresponding normal state is that the medium and high rotating speed and the medium and high current are judged to be normal impact, and when the electric tool is in the locked-rotor working condition, the corresponding state is that the motor is zero rotating speed/ultra-low rotating speed and the continuous high current.
  5. 5. The method for applying the pulse mode to the linear speed regulation of the electric tool according to claim 1 is characterized by comprising a first condition of detecting whether the actual phase change time is the same as the preset phase change time or not in a motor starting stage, judging that the machine works normally if the actual phase change time is the same as the preset phase change time, directly judging to enter the phase change if the actual phase change time is different from the preset phase change time, and comparing the subsequent judging condition with the previous phase change time if the actual phase change time is the same after the normal operation in the starting stage, and judging to work normally if the actual phase change time is different from the preset phase change time.
  6. 6. The method for applying the pulse mode to the linear speed regulation of the electric tool is characterized by comprising the steps of judging whether a current sampling value is changed by a current detection module in a main control chip, judging whether the current is in an ascending or descending trend, further detecting whether an ascending segment meets a detection time window or not when the ascending trend is detected, judging that the ascending detection is successful when the ascending trend is detected, detecting that the number of detection pairs is increased by 1, switching to detect a descending trend at the moment, judging whether the current is in the descending trend or not, judging whether the descending segment meets the detection time window or not if the descending trend is met, judging that the descending detection is successful when the descending trend is detected, switching to detect the ascending trend if the condition is met, setting a threshold value for each detection time window, switching the detection trend if the condition is met, returning to an initial detection stage if the condition is not met, and returning to the initial detection stage until all detection pairs are met, namely being in an 'impact state' at the moment.

Description

Application method of pulse mode in linear speed regulation of electric tool Technical Field The invention relates to an operation method of an electric tool, in particular to an application method of a pulse mode in linear speed regulation of the electric tool. Background Impact drivers are a common type of power tool whose core performance is determined by the built-in impact system. The impact system can switch two working states according to the load of the output shaft, namely, when the output shaft is in a low-load working condition (such as screwing in a no-load screw, fastening a low-hardness material and the like), the impact system reliably transmits the torque output by the main shaft, the output shaft synchronously rotates along with the main shaft to realize continuous linear torque output, the working mode is defined as a non-impact output state, and when the output shaft encounters a high-load working condition (such as screwing in a limit, working of a high-hardness material and the like), the impact system generates continuous impact, so that the output shaft intermittently outputs high-strength torque (energy) to overcome the high load, and the working mode is defined as an impact output state. For easy understanding, when the impact system is just switched from the non-impact output state to the impact output state, the output torque corresponding to the main shaft is taken as a critical technical parameter, which is called critical impact torque (i.e. critical impact condition), and is one of the core basis of the impact system design. In the control logic of the existing impact screwdriver, the output torque of the main shaft and the switching stroke are in positive correlation, namely, the larger the switching stroke on the operating handle is, the higher the output power of the motor is, and the larger the torque transmitted to the main shaft through the transmission mechanism is. In the actual operation process, when the output power of the motor cannot meet the current load requirement and the output torque of the main shaft does not reach the critical impact torque (insufficient to overcome the pretightening axial force of the impact spring), the impact system cannot complete the impact switching action, and the impact system falls into a stagnation state in which the output shaft cannot rotate, which is called locked-rotor in the industry. The phenomenon of locked rotor not only causes the operation to be interrupted, but also can aggravate the heating of the motor and shorten the service life of the transmission part, so that the problem is avoided by technical means. The current solutions to the problem of locked rotor in the market mainly comprise the steps of firstly, collecting load signals in real time through a load detection module, when the load is detected to reach a preset threshold value, momentarily improving the output power of a motor through a controller according to a preset program to enable the torque of a main shaft to quickly break through critical impact torque and drive an impact system to enter an impact state, secondly, synchronously judging whether the current output power of the motor is lower than the power required by critical impact after the load detection module detects that the load exceeds the standard, and if the load cannot reach the impact condition through power adjustment, directly triggering the locked rotor to report errors, and reminding a user to stop the machine for checking. The first scheme can avoid operation interruption caused by power deficiency to a certain extent, but has the obvious technical defects that sudden rising of the output energy of a motor can cause abrupt change of the rotating speed and torque of a main shaft, and the applicability is poor, and the sudden rising of the torque can generate larger reaction force which can drive the wrist of a user to unexpectedly twist, so that the operation comfort is reduced, the operation precision is possibly reduced due to the out-of-control of the wrist, and potential safety hazards exist. The second scheme directly interrupts the operation, reduces the operation efficiency of the tool, and cannot meet the continuous operation requirement. In summary, the conventional blocking response schemes of the impact screwdriver have defects, and the requirements of blocking avoidance, linear power output and operation hand feeling optimization cannot be met. Therefore, it is needed to develop a new power output control mode, which not only can effectively overcome the phenomenon of locked-rotor, but also can keep continuous linear change of energy output of the output shaft, improve the operation stability and the handfeel comfort of the tool, and meet the operation requirements under various working conditions. Disclosure of Invention The invention provides an application method of a pulse mode in linear speed regulation of an electric tool, which solves the problem that in the prior ar