KR100699197B1 - Electromotion Trim Scissors - Google Patents

Abstract

Provided are electric pruning scissors, which prevent the damage and trouble of a motor by rotating a motor reversely in an abnormal state and have a one-touch function capable of operating a blade according to the preset operation number and stopping at the preset position. The electric pruning scissors comprise a fixed blade(213) and a movable blade(215), and perform a pruning work by operating the movable blade(215) using the driving force generated by changing rotatory power of a DC motor(201). The electric pruning scissors have a control-power part that supplies a DC electric source to the DC motor(201). The control-power part comprises: a switching part that interrupts the DC electric source to be supplied to the motor(201) according to a certain control command or switches the phase of the DC electric source into a reverse phase; a current sensor that detects current intensity of the DC electric source to be supplied to the motor(201); and a motor control part, which judges that the motor(201) is overloaded when the current intensity sensed by the current sensor is over a preset value, and then controls that the control command is output to the switching part so as to convert the phase of the DC electric source into a reverse phase. If the motor(201) is overloaded, the control-power part is configured to escape the motor(201) from an overload state by rotating the motor(201) reversely.

Description

Electric Battery Scissors {Electromotion Trim Scissors}

1 is a configuration diagram of electric pruning shears according to the present invention;

2 is a block diagram of a blade unit and a driving unit of the electric pruning shears according to an embodiment of the present invention;

3 is a cross-sectional view of the blade unit and the driving unit of the electric pruning shears of FIG.

4 to 6 is an operating state of the blade unit and the driving unit of the electric pruning shears of FIG.

7 is a block diagram of a control-power supply unit of electric pruning shears according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

110: drive unit 130: blade unit

150: control-power unit 151: input / output unit

153: AC power terminal 170: mounting portion

201: motor 203: planetary reducer

205: drive gear 207: bed

209: driven gear 211: cam roller

213: fixed blade 215: movable blade

219: sensor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electric pruning shears and, more particularly, one-touch control to operate only a predetermined number of times by a reverse rotation function and / or one-touch control to prevent the electric pruning shears. It is related with the automatic battery scissors provided with a function.

Generally, pruning shears, chainsaws or knives are used for pruning various crops or trees for fruit trees, landscaping, forests and flowers.

Conventional pruning shears are very time consuming because they rely solely on the manpower of the worker, and are inevitably degraded. In order to improve this, many inventions related to electric pruning shears that operate based on the driving force of a motor have been applied.

Applicant's Patent No. 0645595 regarding the electric pruning shears already held, the blade of the pruning shears is composed of a fixed blade and a movable blade fixed to the body. The movable blade is repeatedly moved by a predetermined section about the rotating shaft formed on the fixed blade, thereby performing a battery operation with the fixed blade. The rotary motion of the movable blades is repeatedly carried out unconditionally by the rotational force of the motor which rotates in only one direction.

In the case of using the conventional electric pruning shears, in particular, if you want to cut a branch that requires a driving force more than the available load of the motor, the blade of the pruning shears may not be able to cut the branches. In addition, because the blade is driven by the rotational force to rotate in only one direction, the blade of the pruning shear is caught in the branches, it can be in a state that can not escape the pinched state. At this time, further battery operation may be impossible.

In this state, the motor will continue to be overloaded, resulting in damage to the motor as well as other components. A fuse may be used to prevent such a situation, but this method does not eliminate inconvenience of the user.

It is an object of the present invention to control the motor to rotate in reverse when the blade during the battery operation, despite the supply of power, to escape the overall abnormal state including damage to the motor, An electric pruning shear having a rotating function is provided.

Another object of the present invention is to provide electric pruning shears having a one-touch function in which the blade stops at a preset position after the blade is repeatedly operated in response to a user's one-time button operation.

In order to achieve the above object, according to the present invention, the electric pruning shears having a fixed blade and a movable blade, and performing the battery operation by operating the movable blade with a driving force generated by converting the rotational force of a predetermined DC motor, the motor Control-power supply for supplying direct current power.

Here, the control power supply unit includes a switching unit, a current sensor and a motor control unit. The switching unit interrupts the DC power supplied to the motor or switches the phase of the DC power in reverse phase according to a predetermined control command, and the current sensor detects the strength of the current of the DC power supplied to the motor.

The motor controller determines that the motor is overloaded when the intensity of the current sensed by the current sensor is greater than or equal to a preset value, and outputs the control command to the switching unit to change the phase of the DC power source to reverse phase. As a result, when the motor is in an overload state, the motor is automatically rotated to escape from the overload state.

The sensor unit may further include a sensor unit configured to detect whether the movable blade reaches a preset position and output the detected position information to the control power supply unit. In this case, the motor control unit controls the switching unit to reverse the phase of the DC power, and when the position information is received from the sensor unit, outputs the control command to the switching unit to supply the DC power. Can be controlled to block.

Electric pruning shears according to another embodiment of the present invention may further include a sensor unit and a one-touch switch. Here, the sensor unit detects whether the movable blade reaches a preset position, outputs the detected position information to the control power supply unit, and the one-touch switch issues a one-touch control command of a user instructing to perform a one-touch function. Receive input. In addition, the one-touch function means that the movable blade is stopped at the predetermined position after repeatedly operating the predetermined number of times of operation.

Here, the motor control unit, when receiving the one-touch control command from the one-touch switch, outputs the control command to the switching unit for the number of times of operation calculated according to the position information received from the sensor unit to the DC power source This can be controlled to be output to the motor.

The control-power supply unit of the electric pruning shears of the present invention may further include a battery charged with DC power to be supplied to the motor and a charge / discharge control unit. Here, the charge / discharge control unit receives a predetermined AC power, converts it into DC power, charges the battery, and outputs DC power charged in the battery to the switching unit under the control of the motor controller.

According to still another embodiment of the present invention, the electric pruning shear having a fixed blade and a movable blade and performing the battery operation by operating the movable blade with a driving force generated by converting a rotational force of a predetermined DC motor includes a sensor unit and a control unit. It includes a power supply.

The sensor unit detects whether the movable blade reaches a preset position, outputs the detected position information, and the control-power unit supplies DC power to the DC motor.

Here, the control power supply unit includes a switching unit and a control power supply unit.

The switching unit controls the DC power supplied to the motor according to a predetermined control command or switches the phase of the DC power in reverse phase, and the control-power supply unit rotates the movable blade calculated based on the position information of the sensor unit. When the speed is less than or equal to a preset value, the control command is output to the switching unit to control the phase of the DC power source to be reversed.

The motor control unit may determine that the rotational speed of the movable blade is less than or equal to the set value when the position information is not received within the preset time after receiving the position information from the sensor unit.

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 is a block diagram of electric pruning shears according to the present invention.

Referring to FIG. 1, the electric pruning shears 100 includes a driving unit 110, a blade unit 130, a control power supply unit 150, and a mounting unit 170. The electric pruning shears 100 of FIG. 1 are examples of using a rechargeable battery as a DC power source, and a part for supplying power may be separated from the blade.

The driving unit 110 drives the blade unit 130 by the driving force generated by the DC motor and the gear combination, and transmits the position information of the blade to the control power supply unit 150 by monitoring the position of the blade including a sensor. The blade unit 130 includes two blades to perform the battery operation.

The control-power supply unit 150 supplies DC power for the operation of the driving unit 110, and controls the power supplied to the driving unit 110 so that the driving unit 110 performs a reverse rotation function and a one-touch function.

The DC power supplied by the control-power supply unit 150 may use either a rechargeable battery or an adapter converting AC power into DC power or both.

The DC power supplied by the control-power supply unit 150 of FIG. 1 uses a rechargeable battery, and the control-power supply unit 150 inputs an input / output unit 151 connected to the driving unit 110 and an AC power for charging the battery. The receiving AC power supply terminal 153 is included.

The control-power supply unit 150 determines whether or not the battery operation of the blade unit 130, the direct current supplied to the drive unit 110 to escape the abnormal state of the overall pruning shears 100 including the motor of the drive unit 110 By changing the phase of the power supply, the blade is controlled to rotate in reverse.

The control-power supply unit 150 detects the strength of the current of the DC power supplied to the driving unit 110 or determines whether the battery operation of one cycle of the blade unit 130 is performed within a preset time to determine the shear of the scissors 100. Judge whether it is abnormal.

Accordingly, the electric pruning shears 100 monitors an abnormal state such as an overload occurring during the battery operation, and stops the battery operation in progress and reverses the blade by rotating the blade if it is determined that the overload is detected. Damage to a circuit part can be prevented.

The electric pruning shears 100 of the present invention perform a predetermined number of operation (preferably one time) of battery operation according to a user's one-touch control command, and then, the positions of the two blades are set to a preset position. One-touch operation to automatically return can be performed. To this end, the electric pruning shears 100 is formed with a one-touch switch for receiving a user's one-touch control command.

The position of the two blades automatically returned by the one-touch operation is preferably a state in which the two blades do not open each other (hereinafter referred to as a 'closed state'). In addition, another example of the position of the two blades that are automatically returned by the one-touch operation may be a state in which the two blades can form the largest angle (hereinafter referred to as a 'full open state').

For the one-touch function, the control-power supply unit 150 receives the switch contact signal of the driving unit 110 and receives the position information of the blade from the sensor formed in the driving unit 110. When the control-power supply unit 150 receives the switch contact signal (one-touch control command of the user) of the driving unit 110, the control-power unit 150 controls the power supplied to the driving unit 110, and then operates the blade for a predetermined number of times, and then sets a preset position. (E.g., closed state).

The mounting unit 170 is configured to mount the control power supply unit 150 to the user's body, and is coupled to the control power supply unit 150. As illustrated in FIG. 1, an example of the mounting unit 170 may be a backrest with a suspender formed to have a back. According to the embodiment, other methods other than the losing method may be possible.

2 to 6, the configuration of the driving unit 110 and the blade unit 130 together with the general operation of the electric pruning shears 100 will be described first.

2 is a block diagram of the blade unit and the driving unit of the electric pruning shears according to an embodiment of the present invention, Figure 3 is a cross-sectional view of the blade and the driving unit of the electric pruning shears of Figure 2, and Figures 4 to 6 It is an operation state diagram of the blade part and the drive part of electric pruning shears.

First, the driving unit 110 will be described. The rotational force of the motor 201 driven by the DC power supplied from the control-power supply unit 150 is transmitted to the driving gear 205 via the planetary reducer 203. The motor 201 is a DC motor driven by a DC power source. When the incoming DC power phase is reversed, its rotation direction is changed.

The drive gear 205 is implemented in a form that the rotation axis is coupled to one side of the bed 207. The rotational force of the drive gear 205 is transmitted to the driven gear 209 connected at a predetermined reduction ratio.

The rotational force of the drive gear 205 is converted by the driven gear 209 into a rotational force that is rotated about an axis perpendicular to the longitudinal direction to enable the operation of the blade unit 130.

In order to transmit power to the blade 130, cam rollers 211 are integrally formed at one of both sides of the driven gear 209 to revolve around the axis of the driven gear 209.

The blade portion 130 is formed at an edge of a surface on which the driven gear 209 is formed on one side of the bed 207. The blade unit 130 includes a fixed blade 213 and a movable blade 215.

One side of the fixed blade 213 is fixed to the bed 207, and has a shape of a blade bent to form an arc from a portion fixed to the bed 207.

The movable blade 215 has a rotary shaft 217 in common with the fixed blade 213 to have the shape of a conventional pruning shears together with the fixed blade 213, the blade portion of the movable blade 215 cam roller 211 In conjunction with the revolving motion of) will be repeated within a predetermined angle (between closed and fully open).

The cam roller 211 and the movable blade 215 may be formed in such a manner that a restoring elastic member is coupled or the cam roller 211 is fitted into a groove formed in the movable blade 215 to maintain contact therewith.

4 to 6, when the cam roller 211 revolves according to the rotation of the driven gear 209, the movable blade 215 reciprocates a predetermined section about the rotation shaft 217 to perform the shearing. Able to know. At this time, the state of the movable blade 215 shown in Figure 4 corresponds to the closed state, the state of the movable blade 215 shown in Figure 6 corresponds to the fully open state.

In the above, the movable blade 215 is operated with the drive force produced by decelerating the rotational force of the motor 201 by a combination of gears. The above power transmission mechanism is sufficiently replaceable with other power transmission means already known to those skilled in the art.

The driving unit 110 includes a sensor unit 219 and a one touch switch 221.

The sensor unit 219 is used for the reverse rotation function and the one-touch function, and detects the position of the movable blade 215. The sensor unit 219 may detect various positions of the movable blade 215. For example, in addition to the method of detecting the movement of the movable blade 215, the driven gear 209 or the cam roller may be used. The movement of 211 may be detected. In addition, a sensor of the sensor unit 219 may be a magnetic sensor, a proximity sensor or a Hall sensor.

Suppose you use a proximity sensor and return to the closed state after one-touch operation. The sensor unit 219 is located at a point on the revolving surface of the cam roller 211 to determine whether the cam roller 211 is close. In this case, as shown in FIG. 4, the sensor unit 219 may be installed near the position of the cam roller 211 corresponding to the position of the movable blade 215 in the closed state. Therefore, it may be determined that the movable blade 215 is in a closed state when the cam roller 211 is detected.

However, the sensor unit 219 may not necessarily be installed to directly detect the cam roller 211 at a position corresponding to the closed state of the movable blade 215. For example, the cam roller 211 at a specific position may be sensed, and a time point at which the movable blade 215 reaches the closed state may be calculated from the sensing value according to a predetermined calculation method. This calculation method may be determined in consideration of the rotational angular velocity of the driven gear 209 according to the magnitude of the supplied DC current.

In addition, the proximity sensor has a state in which the movable blade 215 is closed based on the position of the cam roller 211 sensed separately from the rotational angular velocity of the driven gear 209 calculated by sensing the proximity of the teeth of the driven gear 209. You can determine when it arrives.

In order to set the movable blade 215 to return to the fully open state after the one-touch operation, the sensor unit 219 may be installed to sense the position of the cam roller 211 corresponding to the fully opened state of the movable blade 215. . For example, the sensor unit 219 is installed near the position of the cam roller 211 shown in FIG.

The position information of the blade detected by the sensor unit 219 is transmitted to the control power supply unit 150.

One-touch switch 221 is installed on the outside of the cover to protect the driving unit 110, receives a one-touch control command from the user to control the corresponding contact signal (hereinafter referred to as 'one-touch contact signal') control-power supply unit 150 To pass). Preferably, the one touch switch 221 may include a function of a general driving switch. For example, when the user operates the one-touch switch 221 once, it becomes a one-touch control command. When the user keeps pressing the one-touch switch 221, it becomes a general control command and continues to operate while pressing.

Contact information of the one-touch switch 221 including the one-touch contact signal is transmitted to the control-power supply unit 150.

The configuration of the drive unit 110 and the blade unit 130 of the electric pruning shears 100 has been described above. Hereinafter, the configuration and operation of the control-power supply unit will be described.

7 is a block diagram of a control-power supply unit of electric pruning shears according to an embodiment of the present invention.

The control-power supply unit 700 may change the rotation direction of the motor 201 operating according to the phase of the DC power supply by changing the phase of the DC power output to the motor 201. The control-power supply unit 700 changes the phase of the supplied DC power when an abnormal state of the pruning shears 100 occurs such that the motor 201 operating in the rotational direction for normal battery operation corresponds to an overload condition. By controlling 201 to rotate in reverse, the drive gear 205, the driven gear 209, and the movable blade 215 can be rotated in reverse to escape the abnormal state.

In order to determine whether the motor 201 is in an overload state, the control-power supply unit 700 detects the strength of the current of the DC power supplied to the motor 201 and determines whether the control-power supply unit 700 is within a preset range. The overload condition can be determined. In addition, the method of detecting the overload state of the motor 201 by the control-power supply unit 700 may be variously implemented, such as a method of detecting the strength of the voltage of the DC power supplied to the motor 201.

In addition, the control-power supply unit 700 is an abnormal state when the movable blade 215 during battery operation fails to perform the battery operation of one cycle within a predetermined time, that is, when the rotational speed of the movable blade 215 is less than or equal to a preset value. Judging by

In addition, the control-power supply unit 700 operates the movable blade 215 for a predetermined number of operations based on the position information received from the driver 110 in response to the user's one-touch control command, For example, the DC power supplied to the motor 201 may be switched to stop in the closed state.

The control-power supply unit 700 corresponds to the control-power supply unit 150 of FIG. 2 and may be described in the same manner. The control-power supply unit 700 controls the input / output unit 701, the AC power terminal 703, the battery 705, the charge / discharge control unit 707, the switching unit 709, the current sensor 711, and the motor control unit 713. Include.

The control-power supply unit 700 is connected to the driving unit 110 via a cable through the input / output unit 701, receives position information and contact information, and provides DC power to the motor 201. In addition, the control-power supply unit 700 receives the AC power for charging the battery 705 through the AC power terminal 703.

The battery 705 is charged by the charge / discharge control unit 707 and discharges a predetermined DC voltage for driving the motor 201.

The charge / discharge controller 707 charges the battery 705 by converting AC power into a predetermined DC voltage under the control of the motor controller 713, and converts the voltage discharged from the battery 705 into the switching unit 709. Output

The switching unit 709 may not only switch the DC power supplied from the charge / discharge control unit 707 to be output to the motor 201 under the control of the motor controller 713, but also switch the phase of the DC power in reverse phase. have. Hereinafter, for convenience of description, the DC power corresponding to the reverse rotation of the movable blade 215 is referred to as the reverse rotation DC power supply, and the DC power corresponding to the normal rotation of the movable blade 215 is referred to as the normal rotation DC power. . The reverse-powered DC power supply is in reverse phase with respect to the normal-powered DC power supply.

The current sensor 711 senses the intensity of the current of the DC power output from the switching unit 709 and outputs it to the motor control unit 713. The current sensor 711 does not necessarily need to be installed at the rear end of the switching unit 709, and may also be installed between the charge / discharge control unit 707 and the switching unit 709 or between the motor 201 and the input / output unit 701. have.

The motor controller 713 controls the overall operation of the control-power source 700.

Basically, when the contact information transmitted from the driving unit 110 is for performing a general operation, the control-power supply unit 700 causes the charge / discharge control unit 707 to switch the voltage charged in the battery 705 to the switching unit 709. ), And controls the switching unit 709 to output the normal power DC power to the motor 201.

When the state of the motor 201 detected from the current sensor 711 is an overload state, the motor controller 713 controls the switching unit 709 to switch the normally rotating DC power being output to the DC power for reverse rotation. To control the movable blade 215 to reverse rotation. The motor controller 713 may determine that the motor 201 is overloaded when the strength of the current detected by the current sensor 711 is greater than or equal to a preset value.

In addition, the motor control unit 713 receives the position information from the sensor unit 219 and, after receiving the previous position information, preferably corresponds to one cycle of battery operation of the movable blade 215. When no new location information is received within a time), it is determined that normal battery operation is not performed. Such an abnormal state may occur due to a lack of torque of the motor 201 due to the case where the intensity of the DC current supplied to the motor 201 is equal to or less than a reference value even if the motor 201 is not necessarily an overload state. Therefore, the motor control unit 713 controls the switching unit 709 to reverse rotation by controlling the switching unit 709 to switch the output of the normal rotation DC power to the reverse rotation DC power.

The motor control unit 713 may control the movable blade 215 to rotate in reverse, so that the motor control unit 713 reverses and stops only by a predetermined angle. For example, if the sensor unit 219 detects the fully open state of the movable blade 215, when the motor control unit 713 receives the position information from the sensor unit 219 again (it is in the fully opened state). The movable blade 215 can be controlled to reverse rotation. In other words, the motor control unit 713 controls the movable blade 215 to reverse rotation, and then stops the reverse rotation when receiving the position information from the sensor unit 219 (when it is in the fully open state). Can be.

When the motor controller 713 receives the one-touch contact signal from the driver 110, the motor controller 713 controls the charge / discharge controller 707 and the switch 709 to output the drive DC power of the motor 201, but the movable blade 215. ) Outputs DC power for the time required to operate the preset number of operations. The motor controller 713 may determine the output time of the DC power corresponding to the operation frequency of the movable blade 215 based on the position information received from the driver 110.

In addition, the motor controller 713 outputs the switching unit 709 based on the position information of the sensor unit 219 to control the position at which the movable blade 215 which has been operated for a predetermined number of times stops at the preset position. To control.

For example, the one-touch operation will be described based on the case where the sensor unit 219 implemented as the proximity sensor is installed near the position of the cam roller 211 corresponding to the closed state.

When the motor controller 713 receives the one-touch contact, the motor controller 713 determines that the position information is received from the driver 110 while controlling the switching unit 709 to switch the DC power supply for normal rotation for the rotation of the motor 201. do. When the number of received location information is one more time than the preset number of operations, the movable blade 215 is operated by the preset number of operations. When the movable blade 215 is in the closed state, the motor control unit 713 receives the position information at the same time as the one-touch contact.

The motor controller 713 controls the switching unit 709 to block the output of the DC power when the last position information is received from the driver 110 to stop the operation when the movable blade 215 is closed. Can be.

Of course, even when operating in accordance with the one-touch function, the reverse rotation function according to the overload can also be performed in parallel.

By the above configuration and method, the control-power supply unit 700 controls the operation of the motor 201 and the movable blade 215.

Although the above has been illustrated and described with respect to preferred embodiments of the present invention, the present invention is not limited to the above-described specific embodiments, it is usually in the technical field to which the invention belongs without departing from the spirit of the invention claimed in the claims. Various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

As described in detail above, the electric pruning shears according to the present invention may cause the motor to rotate out of an abnormal state during an abnormal state such as an overload occurring during battery operation. As a result, since the normal automatic battery scissors operate based on the driving force rotating only in one direction, it is possible to prevent damage and failure of the motor by solving an abnormality such as an overload condition occurring during operation.

In addition, the electric pruning shears may be rotated to reverse the motor even in an abnormal state of the pruning shears, which may occur due to the insufficient torque of the motor due to a lack of the charging power of the battery.

Furthermore, the electric pruning shears of the present invention are provided with a one-touch function in which the blade is repeatedly operated and stopped by a predetermined number of operations by one-time button operation.

Claims (5)

In the electric pruning shears having a fixed blade and a movable blade, and performing the battery operation by operating the movable blade with a driving force generated by converting the rotational force of a predetermined DC motor, And a control-power supply unit for supplying DC power to the DC motor. The control power supply unit, A switching unit for intermitting the DC power supplied to the motor or switching the phase of the DC power in reverse phase according to a predetermined control command; A current sensor for detecting the intensity of the current of the DC power supplied to the motor; And And a motor controller configured to determine that the motor is overloaded when the intensity of the current sensed by the current sensor is greater than or equal to a preset value, and output the control command to the switching unit to control the phase of the DC power to be reversed. If the motor is in an overload state, the electric pruning shears, characterized in that to rotate out of the overload state. The method of claim 1, A sensor unit for detecting whether the movable blade reaches a preset position and outputting the detected position information to the control-power unit; The motor control unit, After controlling the switching unit to change the phase of the DC power to the reverse phase, when the position information is received from the sensor unit, and outputs the control command to the switching unit to control to cut off the supply of the DC power Electric pruning shears. The method of claim 1, A sensor unit for detecting whether the movable blade reaches a preset position and outputting the detected position information to the control-power unit; And And a one-touch switch which receives a one-touch control command of a user instructing to perform a one-touch function to stop the movable blade at the preset position after repeatedly operating the movable blade for a preset number of operations. The motor control unit, When the one-touch control command is received from the one-touch switch, the control command is output to the switching unit for a time corresponding to the operation frequency calculated according to the position information received from the sensor unit, so that the DC power is output to the motor. Electric pruning shears characterized in that. In the electric pruning shears having a fixed blade and a movable blade, and performing the battery operation by operating the movable blade with a driving force generated by converting the rotational force of a predetermined DC motor, A sensor unit for detecting whether the movable blade reaches at least one preset position and outputting the detected position information; And And a control-power supply unit for supplying DC power to the DC motor. The control power supply unit, A switching unit for intermitting the DC power supplied to the motor or switching the phase of the DC power in reverse phase according to a predetermined control command; And And a motor controller configured to output the control command to the switching unit to change the phase of the DC power to the reverse phase when the rotational speed of the movable blade calculated based on the position information of the sensor is equal to or less than a preset value. Electric pruning shears. The method of claim 4, wherein The sensor unit is installed to detect whether the movable blade reaches a specific one position, and outputs the detected position information, The motor controller, when receiving the position information from the sensor unit does not receive new position information within a predetermined time, the electric pruning shears, characterized in that it determines that the rotation speed of the movable blade is less than the set value. .

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