Method, device and power tool for recognizing dangerous operation of the power tool

Abstract

The application discloses a method for identifying dangerous operation of an electric tool, wherein a cutting unit of the electric tool performs a rotating cutting action when in operation, and the method comprises the following steps: detecting a first angular velocity of the cutting unit moving away from or toward a load applying direction and a second angular velocity opposite to the direction of the first angular velocity in real time; comparing an absolute value of the first angular velocity with a first threshold value; if the absolute value of the first angular velocity is greater than or equal to the first threshold value, it is judged that the electric tool has recoil; comparing an absolute value of the second angular velocity with a second threshold value; if the absolute value of the second angular velocity is greater than or equal to the second threshold value, it is judged that the electric tool has breakdown; and the first threshold value is not equal to the second threshold value.

Description

Technical Field

[0001] This invention relates to a control method and apparatus, and more particularly to a method and apparatus for recognizing the operation actions of power tools. Background Technology

[0002] Power tools can sometimes encounter unexpected situations during use. For example, when an operator is cutting a workpiece with a chainsaw, if the chainsaw encounters an obstacle, such as the chain hitting an object at the end of the guide plate or the chainsaw being clamped by a wood saw, the chainsaw will be subjected to a huge reaction force, causing it to rebound uncontrollably towards the operator or move in the opposite direction of the normal processing direction of the workpiece. This situation often leads to serious accidental injuries.

[0003] In addition, in some cases, the chainsaw may suddenly move in the same direction as the normal processing direction of the workpiece, which can also cause injury to the operator.

[0004] To prevent such accidental injuries, traditional chainsaws are equipped with mechanical braking devices, such as those attached to the front handle guard. When the chainsaw suddenly accelerates in a certain direction, such as a "backlash" towards the operator's head, the mechanical braking device can be activated to stop the cutting chain. However, this mechanical braking device relies on the operator's reaction speed in dangerous situations, still carries a high risk, and adding an extra mechanical braking device increases the complexity, size, and weight of the power tool itself, and its sensitivity is not adjustable. Summary of the Invention

[0005] One of the objectives of this invention is to provide a method for identifying dangerous operations of power tools, which can identify dangerous operating actions of power tools with simple configuration and high sensitivity, thereby providing reliable safety protection for operators.

[0006] To achieve the above objectives, the present invention proposes a method for identifying dangerous operation of power tools, wherein the cutting unit of the power tool performs a rotary cutting action during operation, and the method includes the following steps:

[0007] Real-time detection of the first angular velocity of the cutting unit moving away from or toward the direction of the applied load, and the second angular velocity opposite to the direction of the first angular velocity;

[0008] The absolute value of the first angular velocity is compared with a first threshold: if the absolute value of the first angular velocity is greater than or equal to the first threshold, it is determined that the power tool has recoiled; the absolute value of the second angular velocity is compared with a second threshold: if the absolute value of the second angular velocity is greater than or equal to the second threshold, it is determined that the power tool has broken down; the first threshold is not equal to the second threshold.

[0009] In some implementations, the first angular velocity is the angular velocity of movement away from the direction in which the load is applied.

[0010] Another object of the present invention is to provide a device for identifying dangerous operation of power tools.

[0011] Based on the above-mentioned objectives, the present invention also provides a device for identifying dangerous operations of power tools, implemented as described above. The device includes an angular velocity sensor and a detection unit connected to the angular velocity sensor for data transmission; wherein:

[0012] The angular velocity sensor detects the first angular velocity and the second angular velocity;

[0013] The detection unit compares the absolute value of the first angular velocity with a first threshold. If the absolute value of the first angular velocity is greater than or equal to the first threshold, it determines that the power tool has recoiled. The unit also compares the absolute value of the second angular velocity with a second threshold. If the absolute value of the second angular velocity is greater than or equal to the second threshold, it determines that the power tool has broken down.

[0014] Another object of the present invention is to provide an electric tool that has a simple structure and high safety performance and flexibility of use.

[0015] In view of the above-mentioned objectives, the present invention also provides an electric tool whose cutting unit performs a rotary cutting action during operation, the electric tool having the device described above.

[0016] In some embodiments, the power tools described in this invention may include chainsaws, particularly pruning saws.

[0017] The method and apparatus for identifying dangerous operations of power tools described in this invention detect the angular velocity of the power tool in different directions and set different judgment thresholds for recoil and breakdown, thereby achieving better identification results and high flexibility. This not only better protects user safety but also meets the needs of rapid tool cutting and prevents accidental triggering that leads to over-protection.

[0018] The power tool described in this invention combines high cutting efficiency with excellent safety protection. Attached Figure Description

[0019] Figure 1 An electric tool to which this invention is applicable is schematically shown.

[0020] Figure 2 The flowchart illustrates the steps of one embodiment of the method for identifying hazardous operation of power tools according to the present invention.

[0021] Figure 3The flowchart illustrates the steps of another embodiment of the method for identifying hazardous operation of power tools according to the present invention.

[0022] Figure 4 The diagram shows a structural framework of one embodiment of the device for identifying dangerous operation of power tools according to the present invention.

[0023] Figure 5 The diagram shows a structural framework of another embodiment of the device for identifying dangerous operation of power tools according to the present invention. Detailed Implementation

[0024] The method and apparatus for identifying dangerous operation of power tools according to the present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments. However, such explanation and description do not constitute an undue limitation on the technical solution of the present invention.

[0025] Rotary cutting power tools, such as chainsaws, are used to cut workpieces. When a chainsaw is cutting, a sprocket located at the end of the chainsaw guide plate or inside the chainsaw casing is driven by a motor to make the cutting unit saw chain rotate at high speed around the guide plate. The cutting teeth on the saw chain continuously contact the object being cut, cutting and tearing the object through cutting and tearing actions.

[0026] For example, when the operator holds a chainsaw to Figure 1 When cutting a workpiece in the vertical position shown, the direction perpendicular to the paper or the guide plate used to mount the cutting unit 100 can be defined as the Z-axis (i.e., perpendicular to the XOY plane). The positive direction of the Y-axis is defined as vertically upward, and the direction in which the saw chain of the cutting unit 100 points during the cutting process is the positive direction of the X-axis. When the operator uses the lower edge 101 of the cutting unit for cutting, the cutting unit will apply a downward load or rotate counterclockwise downward and apply a load. If the chainsaw encounters an obstacle at this time, the cutting unit 100 of the chainsaw may be subjected to a huge reaction force, and suddenly move towards the operator's head or away from the direction of the applied load of the cutting unit, for example, as... Figure 1 As shown, in the vertical position of the chainsaw, it will suddenly bounce uncontrollably towards the operator from the positive half-axis of the X-axis to the positive half-axis of the Y-axis, that is, along the clockwise upward R direction. This situation is called "backlash". If left uncontrolled, it will often cause serious accidental injury to the operator.

[0027] Additionally, when the operator holds the chainsaw... Figure 1 In the vertical pose shown, when cutting using the upper edge 102 of the cutting unit, the cutting unit applies a load upwards or rotates clockwise upwards while applying a load. If the load disappears at this time, the chainsaw's cutting unit 100 may suddenly move towards the operator's head or in the direction of the applied load, for example... Figure 1 As shown, in the vertical position of the chainsaw, it will suddenly bounce uncontrollably towards the operator from the positive half-axis of the X-axis to the positive half-axis of the Y-axis, that is, along the clockwise upward R direction. This situation is also known as "backlash". If left uncontrolled, it will often cause serious accidental injury to the operator.

[0028] In addition, in some cases, when the operator holds such... Figure 1 The chainsaw shown is Figure 1 When cutting a workpiece in the vertical position shown (Y direction is vertical), if the lower edge 101 of the cutting unit is used for cutting, for example, when the chainsaw cutting is nearing completion, or when the load suddenly disappears, the chainsaw may uncontrollably move suddenly along the normal processing direction of the workpiece (i.e., towards the direction of applied load), causing the high-speed rotating cutting unit 100 to accidentally come into contact with surrounding objects. This situation is called "breakdown". For example Figure 1 As shown, when the chainsaw is in a vertical position and the cutting unit 100 rotates downwards or counterclockwise to apply a load to cut the workpiece, the sudden loss of load near the end of the cutting process may cause the cutting unit 100 to continue moving uncontrollably along the normal processing direction of the workpiece (i.e., towards the direction of the applied load). This could result in the cutting unit hitting the ground or even cutting into the user's body. Therefore, "penetration" can also cause accidental injury to the operator, but its risk is not as high as "recoil."

[0029] To prevent such accidental injuries, traditional chainsaws are equipped with mechanical braking components, such as a separate auxiliary handle mounted on the casing. Holding the auxiliary handle allows for better grip on the tool, reducing the risk of impact. In the event of recoil, the hand holding the auxiliary handle rotates the front stop in front of it, thus braking and reducing the risk of recoil. However, adding an additional mechanical braking device increases the complexity of the power tool itself, increasing its size and weight, and its sensitivity is not adjustable. Furthermore, as a type of chainsaw, the pruning saw is characterized by its light weight, compact structure, and flexible use. Currently, some pruning saws provide an auxiliary grip position through optimized casing design, thus serving a gripping function. Although this design is simple, it still relies on the operator's reaction speed in dangerous situations. Moreover, while these auxiliary handle designs facilitate applying downward force to accelerate cutting, they present the challenge of applying upward force to prevent the tool from falling. In practical applications, the light weight of the pruning saw often requires the user to apply a certain amount of downward pressure to the auxiliary grip handle to accelerate cutting. As the cutting nears completion, the sudden loss of load requires the user to release downward pressure and hold the tool to prevent it from falling further to the ground or into their lower body. However, due to lack of experience and the design of the pruning saw's auxiliary handle, which makes it difficult to pull the tool upwards, there is a risk of failing to hold the tool in time after accelerating the cut, causing the high-speed rotating chain to accidentally contact the ground or even cut into the user's body. Furthermore, the pruning saw still faces the traditional risk of recoil.

[0030] Based on this, the present invention provides a method for identifying dangerous operations of power tools in one embodiment, and in particular a method for identifying dangerous operations of rotary cutting power tools.

[0031] like Figure 2 As shown, in some embodiments, the method for identifying hazardous operation of power tools may include the steps of:

[0032] S1: Real-time detection of the first angular velocity α1 of the cutting unit moving toward or away from the direction of the applied load, and the second angular velocity α2 opposite to the direction of the first angular velocity;

[0033] S2: Compare the absolute value of the first angular velocity α1 with the set first threshold A1. If the absolute value of the first angular velocity α1 is greater than or equal to the first threshold A1, it is determined that the power tool has recoiled. Compare the absolute value of the second angular velocity α2 with the set second threshold A2. If the absolute value of the second angular velocity α2 is greater than or equal to the second threshold A2, it is determined that the power tool has broken down.

[0034] Based on the above description, the first angular velocity in this invention corresponds to the recoil determination angular velocity, while the second angular velocity corresponds to the breakdown determination angular velocity.

[0035] In some implementations, when the power tool is in a vertical position, a sudden upward movement of the cutting unit, especially toward the operator's head, is considered to pose a risk of recoil, while a sudden downward movement of the cutting unit is considered to pose a risk of penetration.

[0036] Therefore, in some implementations, when the power tool is Figure 1 When the vertical pose shown is cut downwards by the lower edge 101 of the cutting unit, the first angular velocity α1 of the cutting unit moving away from the direction of the applied load and the second angular velocity α2 moving in the opposite direction of the first angular velocity are detected in real time to identify recoil and penetration.

[0037] In other embodiments, when the power tool is Figure 1 When the vertical pose shown is used to cut upwards using the upper edge 102 of the cutting unit, the first angular velocity α1 of the cutting unit moving in the direction of the applied load and the second angular velocity α2 in the opposite direction of the first angular velocity are detected in real time to identify recoil and penetration.

[0038] It should be noted that in this invention, the direction of the applied load of the cutting unit can be linear, such as downward in the height direction, or it can be a non-linear curve, such as clockwise or counterclockwise.

[0039] Those skilled in the art will understand that, since the first angular velocity and the second angular velocity are generated based on different actions of the cutting unit, the first angular velocity and the second angular velocity do not exist simultaneously. When the first angular velocity is detected, it can be understood that the second angular velocity is 0, and when the second angular velocity is detected, it can be understood that the first angular velocity is 0.

[0040] In this embodiment, recoil detection and breakdown detection have different sensitivities, therefore the first threshold A1 is not equal to the second threshold A2.

[0041] In some specific implementations, the second threshold A2 is greater than the first threshold A1. This method allows for different sensitivities in recoil and breakdown detection. A higher detection sensitivity is set for recoil directed towards the operator, thus requiring a relatively lower threshold to better protect user safety. Conversely, for breakdown, which is farther from the operator's head and carries a lower risk, a lower detection sensitivity is set—that is, a relatively higher threshold—to accommodate the tool's rapid cutting needs and prevent false triggering leading to over-protection.

[0042] In some more specific implementations, the ratio of the second threshold A2 to the first threshold A1 is ≥1.2. For example, the ratio of the second threshold A2 to the first threshold A1 can be 1.2 to 2.5, or the ratio of the second threshold A2 to the first threshold A1 can be 2 to 2.5. In a specific example, the ratio of the second threshold A2 to the first threshold A1 can be 2.

[0043] By setting the ratio of the second threshold A2 to the first threshold A1 to be ≥1.2, it can be further ensured that the power tool can achieve rapid cutting very efficiently without frequently triggering the breakdown protection, while still being able to detect the recoil hazard with high sensitivity.

[0044] In some more specific implementations, the second threshold A2 can be selected in the range of 300 to 1000° / s.

[0045] In some more specific implementations, the first threshold A1 can be selected in the range of 100 to 700° / s.

[0046] For example, in a specific instance, the first threshold A1 can be set to 100° / s as needed, and the second threshold A2 can be set to 300° / s.

[0047] For example, in another specific instance, the first threshold A1 can be set to 700° / s as needed, and the second threshold A2 can be set to 1000° / s.

[0048] For example, in a specific instance, the first threshold A1 can be set to 300° / s as needed, and the second threshold A2 can be set to 500° / s.

[0049] Those skilled in the art can set the first threshold and the second threshold according to different power tool operating conditions and usage scenarios, so that the sensitivity of recoil and breakdown identification is adjustable and can be adapted to various operating conditions and usage scenarios.

[0050] In some more specific embodiments, the first threshold and the second threshold can be adjusted within the above range according to the cutting current. For example, as the cutting current increases, the values ​​of the first threshold and the second threshold gradually decrease while meeting the above requirements or falling within the above range.

[0051] In some more specific embodiments, the first threshold and the second threshold can be adjusted within the above range according to the cutting speed. For example, as the cutting speed increases, the values ​​of the first threshold and the second threshold gradually decrease while meeting the above requirements or falling within the above range.

[0052] It should be noted that, although Figure 1The display shows the operating state of the power tool in a vertical position. However, in other embodiments, the power tool, especially a rotary cutting power tool, can also perform cutting operations in an inclined position. In this case, the method of the present invention can also detect the first angular velocity of the cutting unit moving away from the direction of the applied load (i.e., towards the operator) and the second angular velocity moving along the direction of the applied load (i.e., away from the operator) in an inclined plane with a certain angle to the vertical plane, and set a first threshold and a second threshold with different values ​​as needed.

[0053] Furthermore, in some other embodiments, power tools, especially rotary cutting power tools, can also perform cutting operations in a horizontal position. In this case, the method of the present invention can also detect the first angular velocity of the cutting unit moving away from the applied load direction (i.e., towards the operator) and the second angular velocity of the cutting unit moving along the applied load direction (i.e., away from the operator) on the horizontal plane. In this case, since the operator is behind the power tool, even if a breakdown occurs, it is mostly manifested as the cutting unit colliding with environmental objects, and the possibility of personal injury to the operator is low. Therefore, the sensitivity of breakdown detection can be further reduced to ensure efficient cutting, that is, the value of the second threshold can be further increased. For example, the ratio of the second threshold A2 to the first threshold A1 can be set to ≥5. For example, in a specific example, the second threshold can be 1000° / s.

[0054] In some implementations, to further ensure the accuracy of recoil and breakdown identification and prevent false identification, the method for identifying dangerous operations of power tools may specifically include:

[0055] When the absolute value of the first angular velocity α1 is greater than or equal to the first threshold A1 for a period of time T1, it is determined that the power tool has experienced recoil; and / or

[0056] When the absolute value of the second angular velocity α2 is greater than or equal to the second threshold A2 for a period of time T2, it is determined that the power tool has broken down.

[0057] In some more specific implementations, the first time period T1 ≤ the second time period T2. In some more specific implementations, for example, the first time period T1 can be 10–40 ms, and the second time period T2 can be 20–50 ms. In a specific example, the first time period can be 10 ms, and the second time period can be 40 ms. This is because, considering that the risk of recoil is higher than that of breakdown, in some implementations, a narrower recoil time window is desired, thereby providing more timely protection.

[0058] Those skilled in the art can set the duration of the first and second time periods according to different power tool operating conditions and usage scenarios, thereby making the sensitivity of recoil and breakdown identification adjustable and adaptable to various operating conditions and usage scenarios.

[0059] In some more specific implementations, the values ​​of the first time period and the second time period can be adjusted within the above range according to the cutting current. For example, as the cutting current increases, the values ​​of the first time period and the second time period gradually decrease while meeting the above requirements or falling within the above range.

[0060] In some more specific embodiments, the values ​​of the first time period and the second time period can be adjusted within the above range according to the cutting speed. For example, as the cutting speed increases, the values ​​of the first time period and the second time period gradually decrease while meeting the above requirements or falling within the above range.

[0061] Based on the identification of dangerous actions of power tools, in order to further protect the operator, in some preferred embodiments, such as Figure 3 The method described in this invention, in addition to steps S1 and S2, further includes step S3: when it is determined that a dangerous operation has occurred with the power tool, an alarm signal is issued, and preferably a stop signal is further issued.

[0062] Of course, in some alternative implementations, when it is determined that a dangerous operation has occurred with the power tool, an alarm signal can be issued, and the operator can stop the machine by performing individual operation after being prompted by the alarm signal.

[0063] In some alternative implementations, when it is determined that a dangerous operation has occurred with the power tool, a stop signal can be issued directly without an alarm.

[0064] In another embodiment of the present invention, an apparatus for identifying dangerous operation of power tools is provided, which is implemented as described above.

[0065] like Figure 4As shown, in some embodiments, the device for identifying dangerous operation of power tools includes an angular velocity sensor 200 and a detection unit 300 connected to the angular velocity sensor for data transmission. The angular velocity sensor 200 detects a first angular velocity and a second angular velocity. The detection unit 300 compares the absolute value of the first angular velocity α1 obtained from the angular velocity sensor 200 with a preset first threshold A1 stored in the detection unit 300. If the absolute value of the first angular velocity α1 is greater than or equal to the first threshold A1, it is determined that the power tool has experienced recoil. The detection unit 300 also compares the absolute value of the second angular velocity α2 obtained from the angular velocity sensor 200 with a preset second threshold A2 stored in the detection unit 300. If the absolute value of the second angular velocity α2 is greater than or equal to the second threshold A2, it is determined that the power tool has experienced breakdown. In this embodiment, the detection of recoil and the detection of breakdown have different sensitivities; therefore, the first threshold A1 is not equal to the second threshold A2.

[0066] In some more specific implementations, the angular velocity sensor can be a gyroscope, which can not only detect the numerical value of the angular velocity, but also indicate the direction of the angular velocity by positive or negative sign. For example, the first angular velocity moving away from the direction of the applied load can be output as a negative value by the angular velocity sensor, and the second angular velocity moving towards the direction of the applied load can be output as a positive value by the angular velocity sensor.

[0067] In some more specific embodiments, the angular velocity sensor may be mounted on the housing of the power tool, with the detection axis of the angular velocity sensor parallel to the normal axis of the cutting unit.

[0068] In some more specific embodiments, the angular velocity sensor may be a single-axis sensor. In other more specific embodiments, the angular velocity sensor may also be a triaxial sensor.

[0069] In addition to identifying dangerous actions of the power tool, and to further protect the operator, in some preferred embodiments, the detection unit 300 is also configured to issue an alarm signal when it is determined that the power tool has performed a dangerous operation, and preferably further issue a stop signal.

[0070] Of course, in some other optional embodiments, the detection unit 300 may also be configured to issue an alarm signal when it is determined that the power tool has been operated in a dangerous manner, and the operator may perform individual operation to stop the machine after being prompted by the alarm signal.

[0071] In some alternative implementations, the detection unit 300 may also be configured to send a stop signal to the motor of the power tool directly without an alarm when it is determined that the power tool has been operating dangerously.

[0072] In some more specific implementations, such as Figure 5 As shown, the device for identifying dangerous operation of power tools may further include an indicator unit 400 connected to the detection unit 300 to display an alarm signal issued by the detection unit.

[0073] In some more specific embodiments, the indicator unit 400 may include at least one of a display screen, an alarm light, an audible alarm, and a vibration alarm.

[0074] It is understood that the detection module described in this invention can be implemented in various ways. For example, it can be implemented as hardware, software, or a combination thereof.

[0075] For example, the detection module may include one or more processors. These processors may use electronic hardware, such as, in some more specific embodiments, a microcontroller (MCU).

[0076] In other embodiments, it may also be a system on chip (SOC), a digital signal processor (DSP), a field-programmable gate array (FPGA), a programmable logic device (PLD), a state machine, gate logic, discrete hardware circuitry, and other suitable processing components configured to perform the various functions described herein.

[0077] In other implementations, the detection module may also be implemented using computer software or any combination of electronic hardware and computer software. Whether these processors are implemented as hardware or software will depend on the specific application and the overall design constraints imposed on the system.

[0078] The functions of the processor, any part of the processor, or any combination of processors provided in this invention can be implemented as software executed by a microprocessor, microcontroller, DSP, or other suitable platform.

[0079] Software can be broadly considered as representing instructions, instruction sets, code, code segments, program code, programs, subroutines, software modules, applications, software applications, software packages, routines, subroutines, objects, running threads, procedures, functions, etc. Software can reside on computer-readable media. Computer-readable media can include, for example, memory, which can be, for example, magnetic storage devices (e.g., hard disks, floppy disks, magnetic stripes), optical discs, smart cards, flash memory devices, random access memory (RAM), read-only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), registers, or removable disks.

[0080] In one embodiment, the present invention also provides a power tool whose cutting unit performs a rotary cutting action during operation, the power tool having the apparatus described above.

[0081] In some more specific embodiments, the power tools described in this invention include chainsaws.

[0082] In some more specific embodiments, the power tools described in this invention include pruning saws.

[0083] Through the methods and apparatus described above, the power tool of the present invention combines high cutting efficiency with excellent safety protection.

[0084] It should be noted that the prior art portion of the protection scope of this invention is not limited to the embodiments given in this application. All prior art that does not contradict the solution of this invention, including but not limited to prior patent documents, prior publications, prior public uses, etc., can be included in the protection scope of this invention.

[0085] Furthermore, the combination of the technical features in this case is not limited to the combination methods described in the claims of this case or the combination methods described in the specific embodiments. All technical features described in this case can be freely combined or combined in any way, unless they contradict each other.

[0086] It should also be noted that the embodiments listed above are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made thereto are those that can be directly derived or easily conceived by those skilled in the art from the content disclosed in the present invention, and should all fall within the protection scope of the present invention.

Claims

1. A method for identifying dangerous operation of power tools, wherein the cutting unit of the power tool performs a rotary cutting action during operation, characterized in that, The method includes the following steps: Real-time detection of the first angular velocity of the cutting unit moving away from or toward the direction of the applied load, and the second angular velocity opposite to the direction of the first angular velocity; The absolute value of the first angular velocity is compared with a first threshold: if the absolute value of the first angular velocity is greater than or equal to the first threshold, it is determined that the power tool has recoiled; the absolute value of the second angular velocity is compared with a second threshold: if the absolute value of the second angular velocity is greater than or equal to the second threshold, it is determined that the power tool has broken down; the first threshold is not equal to the second threshold.

2. The method as described in claim 1, characterized in that, The first angular velocity is the angular velocity of the motion in the direction away from the applied load.

3. The method as described in claim 1, characterized in that, It also includes the steps of: issuing an alarm signal and / or issuing a stop signal when it is determined that the power tool has been operated in a dangerous manner.

4. The method according to any one of claims 1-3, characterized in that, The second threshold is greater than the first threshold.

5. The method as described in claim 4, characterized in that, The ratio of the second threshold to the first threshold is ≥1.

2.

6. The method as described in claim 5, characterized in that, The ratio of the second threshold to the first threshold is 2-2.

5.

7. The method according to any one of claims 1-3, characterized in that, The second threshold ranges from 300 to 1000° / s, and / or the first threshold ranges from 100 to 700° / s.

8. The method according to any one of claims 1-3, characterized in that, The direction of the applied load of the cutting unit is located in the vertical plane.

9. The method according to any one of claims 1-3, characterized in that: Comparing the absolute value of the first angular velocity with the first threshold specifically includes: if the absolute value of the first angular velocity is greater than or equal to the first threshold for a first time interval, then it is determined that the power tool has experienced recoil; and / or Comparing the absolute value of the second angular velocity with the second threshold specifically includes: when the second angular velocity is greater than or equal to the second threshold for a period of time that lasts for a second time interval, it is determined that the power tool has broken down.

10. The method as described in claim 9, characterized in that, The first time period is less than or equal to the second time period.

11. A device for identifying dangerous operation of power tools, characterized in that, The method described in any one of claims 1-10 is further characterized by the following: the device includes an angular velocity sensor and a detection unit connected to the angular velocity sensor for data transmission; wherein: The angular velocity sensor detects the first angular velocity and the second angular velocity; The detection unit compares the absolute value of the first angular velocity with a first threshold. If the absolute value of the first angular velocity is greater than or equal to the first threshold, it determines that the power tool has recoiled. The unit also compares the absolute value of the second angular velocity with a second threshold. If the absolute value of the second angular velocity is greater than or equal to the second threshold, it determines that the power tool has broken down.

12. The apparatus as claimed in claim 11, characterized in that, It also includes an indicator unit connected to the detection unit to display the alarm signal issued by the detection unit.

13. A power tool whose cutting unit performs a rotary cutting action during operation, characterized in that, The power tool has the apparatus as described in claim 11 or 12.

14. The power tool as claimed in claim 13, characterized in that, It includes chainsaws.

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