JP2021058942A - Work machine - Google Patents

Abstract

To provide a technique that can reliably detect the occurrence of kickback in a work machine.SOLUTION: A work machine disclosed in the specification may comprise a work element, a drive part that drives the work element, a driving speed detection unit that detects the driving speed of the drive part, a movement amount detection unit that detects the amount of movement of the work machine, and a brake part that brakes the drive part when predetermined conditions are satisfied with respect to the driving speed of the drive part and the movement amount of the work machine.SELECTED DRAWING: Figure 3

Description

The techniques disclosed herein relate to working machines.

Patent Document 1 discloses a working machine. The work machine is satisfied with a work element, a drive unit for driving the work element, a drive speed detection unit for detecting the drive speed of the drive unit, and predetermined conditions related to the drive speed of the drive unit. In some cases, it is provided with a braking unit that brakes the driving unit. According to the working machine of Patent Document 1, when the driving speed of the driving unit suddenly decreases due to the occurrence of kickback, the driving unit is braked by the braking unit.

Japanese Unexamined Patent Publication No. 2009-241222

In general, the degree of decrease in the driving speed of the driving unit when kickback occurs varies depending on the weight of the working element used. Therefore, in the configuration in which the occurrence of kickback is detected by focusing only on the decrease in drive speed as in the technique of Patent Document 1, the work element is heavy and the drive speed of the drive unit does not decrease so much when kickback occurs. In some cases, the occurrence of kickback may not be detected. The present specification provides a technique capable of reliably detecting the occurrence of kickback in a working machine.

The work machine disclosed in the present specification includes a work element, a drive unit for driving the work element, a drive speed detection unit for detecting the drive speed of the drive unit, and a movement amount for detecting the movement amount of the work machine. A detection unit and a braking unit that brakes the drive unit when predetermined conditions related to the drive speed of the drive unit and the movement amount of the work machine are satisfied may be provided.

When kickback occurs in the work equipment, the drive speed of the drive unit drops sharply, and the position and posture angle of the work equipment also change significantly. According to the above configuration, since it is determined whether or not kickback has occurred by using both the drive speed of the drive unit and the amount of movement of the work equipment, the working element is heavy and the drive unit is heavy when kickback occurs. Even when the driving speed of the vehicle does not decrease so much, the occurrence of kickback can be reliably detected.

It is a perspective view which shows the appearance of the brush cutter 10 which concerns on Example. It is a figure which shows schematic the electric system of the brush cutter 10 which concerns on Example. It is a flowchart which shows the process performed by the processing part 80 of the brush cutter 10 which concerns on embodiment. It is a figure which shows the example of the time-dependent change of the motor rotation speed of the brushless motor 22 when kickback occurs in the brush cutter 10 which concerns on embodiment. It is a figure which shows the example of the time-dependent change of the posture angle of the brush cutter 10 when kickback occurs in the brush cutter 10 which concerns on embodiment.

In one or more embodiments, the work machine determines the work element, the drive unit that drives the work element, the drive speed detector that detects the drive speed of the drive unit, and the amount of movement of the work machine. It may be provided with a movement amount detecting unit to be detected, and a braking unit that brakes the driving unit when predetermined conditions related to the driving speed of the driving unit and the moving amount of the working machine are satisfied.

When kickback occurs in the work equipment, the drive speed of the drive unit drops sharply, and the position and posture angle of the work equipment also change significantly. According to the above configuration, since it is determined whether or not kickback has occurred by using both the drive speed of the drive unit and the amount of movement of the work equipment, the working element is heavy and the drive unit is heavy when kickback occurs. Even when the driving speed of the vehicle does not decrease so much, the occurrence of kickback can be reliably detected.

In one or more embodiments, the braking unit may brake the driving unit when the first predetermined condition related to the driving speed of the driving unit is satisfied. The drive unit may be braked even when the second predetermined condition related to the movement amount of the above is satisfied.

According to the above configuration, it is possible to determine whether or not a kickback has occurred under simplified conditions, so that a kickback can occur as compared with the case where the determination is made using complicated conditions. It can be detected quickly.

In one or more embodiments, the braking unit may determine whether or not the first predetermined condition is satisfied, and if the first predetermined condition is satisfied, the driving unit may be pressed. Braking may be performed, and if the first predetermined condition is not satisfied, it may be determined whether or not the second predetermined condition is satisfied, and if the second predetermined condition is satisfied, the said The drive unit may be braked.

In general, the response speed of the sensor that detects the drive speed of the drive unit is faster than the response speed of the sensor that detects the amount of movement of the work machine. According to the above configuration, the occurrence of kickback can be detected more quickly by first determining the first predetermined condition using the sensor having a high response speed.

In one or more embodiments, the first predetermined condition is that the amount of change in the driving speed of the driving unit in the first predetermined time exceeds the first threshold value, and the driving unit May include that is decelerating.

According to the above configuration, it is possible to quickly detect that the driving speed of the driving unit has decreased due to the occurrence of kickback by a simple determination process.

In one or more embodiments, the second predetermined condition may include that the amount of movement of the working machine in a second predetermined time exceeds a second threshold.

According to the above configuration, it is possible to quickly detect that the position and posture angle of the work machine have changed due to the occurrence of kickback by a simple determination process.

In one or more embodiments, the drive unit may include a motor. The drive speed detection unit may include a rotation speed sensor that detects the rotation speed of the motor.

Normally, when the drive source of the work machine is a motor, a rotation speed sensor for detecting the rotation speed of the motor is provided in order to control the rotation of the motor. According to the above configuration, the occurrence of kickback can be detected by using the rotation speed sensor provided in the motor.

In one or more embodiments, the motion detector may include a gyro sensor that detects the angular velocity of the work equipment.

Normally, when kickback occurs, the posture angle of the work equipment changes significantly. According to the above configuration, the change in the posture angle of the working machine can be detected by using the gyro sensor, and the occurrence of kickback can be reliably detected.

In one or more embodiments, the braking unit may brake the precursor driving unit by changing the wiring of the driving unit.

According to the above configuration, the drive unit can be braked without separately providing a braking mechanism for mechanically braking the drive unit.

In one or more embodiments, the working machine may include an operating paddle and a grip provided on the operating paddle. The working element may be provided at the tip of the operating paddle.

In a work machine in which a work element is provided at the tip of the operating rod, when kickback occurs, the force acting on the grip portion becomes large. According to the above configuration, the occurrence of kickback can be reliably detected in such a working machine.

(Example)
The brush cutter 10 shown in FIG. 1 is a working machine used for weed cutting work. The brush cutter 10 includes an operating paddle 30, a front unit 20 located at the front end 30a of the operating paddle 30, and a rear unit 40 located at the rear end 30b of the operating paddle 30. The operation paddle 30 is a hollow pipe material, and extends linearly from the front end 30a to the rear end 30b. In the following description, the direction in which the operation rod 30 extends is referred to as the front-rear direction, the direction orthogonal to the front-rear direction is referred to as the left-right direction, and the direction orthogonal to the front-rear direction and the left-right direction is referred to as the up-down direction.

The front unit 20 is configured so that the blade 12 can be attached and detached. The blade 12 is a working element used in the brush cutter 10. The blade 12 in this embodiment is a disc blade having a plurality of cutting edges on the peripheral edge, and is made of a metal material. A blade cover 26 is arranged in the vicinity of the front unit 20. The blade cover 26 is fixed to the operating paddle 30 and covers a part of the blade 12.

The rear unit 40 is configured so that the battery pack 44 can be attached and detached. The battery pack 44 is the power source for the brush cutter 10. The battery pack 44 has a plurality of rechargeable battery cells. As an example, the battery pack 44 in this embodiment has a plurality of lithium ion battery cells connected in series. The rear unit 40 is provided with a speed dial 48 and a power switch 50. The speed dial 48 is an operating member operated by the user to adjust the rotational speed of the blade 12. The power switch 50 is an operating member operated by the user to switch the main power of the brush cutter 10 on and off. A gyro sensor 52 (see FIG. 2) is provided inside the rear unit 40. The gyro sensor 52 is, for example, a three-axis gyro sensor capable of detecting angular velocities around the front-rear direction, around the left-right direction, and around the up-down direction.

The operation paddle 30 is provided with a handle 32 for the user to grip. The handle 32 generally has a U-shape, and the central portion thereof is fixed to the operating paddle 30. A right grip 32a is provided at one end of the handle 32, and a left grip 32b is provided at the other end of the handle 32. Normally, the user can use the brush cutter 10 by gripping the right grip 32a with the right hand and the left grip 32b with the left hand.

The right grip 32a is provided with a trigger 34 and a direction selector 36. The trigger 34 and the direction selector 36 are electrically connected to the rear unit 40 by an electric cord 38. The trigger 34 is an operating member operated by the user to operate / stop the blade 12. The direction selector 36 is an operating member operated by the user to switch the rotation direction of the blade 12 between the forward direction and the reverse direction.

As shown in FIG. 2, the brush cutter 10 includes a brushless motor 22 and a hall sensor 24. The brushless motor 22 and the hall sensor 24 are arranged in the front unit 20 and are housed in the housing of the front unit 20. The brushless motor 22 is a prime mover for driving the blade 12, and is mechanically connected to the blade 12. The brushless motor 22 of this embodiment is a three-phase brushless motor, and has a U-phase coil 22u, a V-phase coil 22v, and a W-phase coil 22w. The Hall sensor 24 outputs a predetermined signal according to the rotation position of the brushless motor 22 (to be exact, the rotation position of the rotor of the brushless motor 22).

The brush cutter 10 includes a motor controller 70 and motor power lines 61, 62, 63. The motor controller 70 is located in the rear unit 40 and is electrically connected to the battery pack 44. The motor power lines 61, 62, and 63 electrically connect the motor controller 70 located in the rear unit 40 to the brushless motor 22 located in the front unit 20. The first motor power line 61 is connected to the U-phase coil 22u (or U-phase terminal) of the brushless motor 22, and the second motor power line 62 is the V-phase coil 22v (or U-phase terminal) of the brushless motor 22. The third motor power line 63 is connected to the W-phase coil 22w (or U-phase terminal) of the brushless motor 22. The motor power lines 61, 62, and 63 are arranged along the operating paddle 30 and extend from the rear unit 40 to the front unit 20. With these configurations, the battery pack 44 is electrically connected to the brushless motor 22 via the motor controller 70. That is, the electric power from the battery pack 44 is supplied to the brushless motor 22 via the motor controller 70.

The brush cutter 10 includes sensor power lines 64 and 65 and sensor signal lines 66, 67 and 68. The sensor power lines 64 and 65 are conductive lines that supply operating power from the rear unit 40 to the hall sensor 24. The sensor power lines 64 and 65 are arranged along the operating paddle 30 and extend from the rear unit 40 to the front unit 20. The sensor signal lines 66, 67, and 68 are conductive lines that transmit the output signal of the hall sensor 24 to the motor controller 70. The sensor signal lines 66, 67, 68 are arranged along the operating paddle 30 and extend from the front unit 20 to the rear unit 40.

The brush cutter 10 includes a constant voltage circuit 42 and a cutoff circuit 46. The constant voltage circuit 42 and the cutoff circuit 46 are arranged in the rear unit 40 and are electrically connected to the battery pack 44. The constant voltage circuit 42 generates a power supply voltage supplied to the motor controller 70 and the hall sensor 24. The cutoff circuit 46 is arranged on a circuit that electrically connects the battery pack 44 and the motor controller 70, and can electrically connect / cut off the battery pack 44 and the motor controller 70. The break circuit 46 of this embodiment is, as an example, a field effect transistor (MOSFET).

The motor controller 70 includes switching elements 71, 72, 73, 74, 75, 76, a gate driver 78, and a processing unit 80. The switching elements 71, 72, 73, 74, 75, 76 are field effect transistors, and more specifically, MOSFETs having an insulated gate. The switching element 71 connects the positive electrode side power supply potential of the battery pack 44 to the first motor power line 61. The switching element 72 connects the positive electrode side power supply potential of the battery pack 44 to the second motor power line 62. The switching element 73 connects the positive electrode side power supply potential of the battery pack 44 to the third motor power line 63. The switching element 74 connects the negative electrode side power supply potential of the battery pack 44 and the first motor power line 61. The switching element 75 connects the negative electrode side power supply potential of the battery pack 44 and the second motor power line 62. The switching element 76 connects the negative electrode side power supply potential of the battery pack 44 and the third motor power line 63.

The gate driver 78 switches each switching element 71, 72, 73, 74, 75, 76 between conducting and non-conducting according to the control signal output from the processing unit 80, so that each motor power line 61 , 62, 63 are controlled to rotate the brushless motor 22. If the gate driver 78 makes all the switching elements 71, 72, 73, 74, 75, and 76 non-conducting while the brushless motor 22 is rotating, the power supply to the brushless motor 22 is cut off, and the brushless motor 22 Continues to rotate due to inertia and then stops. Further, if the gate driver 78 makes the switching elements 71, 72, 73 non-conducting and the switching elements 74, 75, 76 conductive while the brushless motor 22 is rotating, the brushless motor 22 is subjected to a so-called short-circuit brake. , The rotation of the brushless motor 22 stops immediately.

The processing unit 80 outputs a control signal to the gate driver 78 in response to the signals output from the hall sensor 24, the trigger 34, the direction selector 36, the speed dial 48, and the gyro sensor 52. When the brushless motor 22 is rotating, the processing unit 80 can specify the rotation position of the brushless motor 22 based on the output signal from the hall sensor 24. Then, the processing unit 80 adjusts the operation of the switching elements 71, 72, 73, 74, 75, 76 according to the rotation position of the brushless motor 22, and the current flowing through the coils 22u, 22v, 22w of the brushless motor 22. The rotation of the brushless motor 22 can be controlled by switching the direction of.

Further, the processing unit 80 controls the drive / stop, rotation direction, rotation speed, etc. of the rotation of the brushless motor 22 according to the output signals from the trigger 34, the direction selector 36, and the speed dial 48.

The processing unit 80 can specify the rotation speed of the brushless motor 22 based on the output signal from the hall sensor 24. Therefore, the hall sensor 24 and the processing unit 80 form a rotation speed sensor 82 that detects the rotation speed of the brushless motor 22.

Further, the processing unit 80 can specify the posture angle of the brush cutter 10 based on the output signal from the gyro sensor 52. Therefore, the gyro sensor 52 and the processing unit 80 form a posture angle sensor 84 that detects the posture angle of the brush cutter 10.

Hereinafter, the processing performed by the processing unit 80 will be described with reference to FIG. When the power switch 50 is operated by the user from off to on and the power supply voltage is supplied to the processing unit 80 via the constant voltage circuit 42, the processing unit 80 executes the process shown in FIG.

In S2, the processing unit 80 waits until the trigger 34 switches from off to on. When the trigger 34 is turned on (yes), the process proceeds to S4.

In S4, the processing unit 80 outputs a control signal to the gate driver 78 to drive the brushless motor 22. As a result, the brushless motor 22 starts rotating.

In S6, the processing unit 80 starts specifying the rotation speed of the brushless motor 22 based on the output signal from the hall sensor 24. While driving the brushless motor 22, the processing unit 80 rotates the brushless motor 22 in the rotation direction selected by the direction selector 36 based on the output signals from the hall sensor 24, the direction selector 36, and the speed dial 48. In addition, the operation of the switching elements 71, 72, 73, 74, 75, 76 is controlled so as to rotate at the rotation speed selected by the speed dial 48.

In S8, the processing unit 80 starts specifying the posture angle of the brush cutter 10 based on the output signal from the gyro sensor 52.

In S10, the processing unit 80 determines whether or not the elapsed time since the trigger 34 was turned on in S2 has reached a predetermined time (for example, 100 ms). If the elapsed time since the trigger 34 is turned on has not reached the predetermined time (NO), the rotation speed of the brushless motor 22 is not yet stable, and it cannot be determined whether or not kickback is necessary. , Processing proceeds to S12.

In S12, the processing unit 80 determines whether or not the trigger 34 has been turned off. If the trigger 34 is not turned off (NO), the process returns to S10. If the trigger 34 is off (YES), the process proceeds to S14.

In S14, the processing unit 80 switches all the switching elements 71, 72, 73, 74, 75, 76 to non-conductivity and stops the power supply to the brushless motor 22. As a result, the brushless motor 22 continues to rotate due to inertia and then stops. After S14, the process returns to S2.

In S10, when the elapsed time since the trigger 34 is turned on reaches a predetermined time (YES), the processing unit 80 determines that the rotation speed of the brushless motor 22 is stable, and the processing proceeds to S16. move on.

In S16, the processing unit 80 determines whether or not the rotation speed of the brushless motor 22 is equal to or higher than a predetermined rotation speed (for example, 5000 rpm). When the rotation speed of the brushless motor 22 is less than the predetermined rotation speed (NO), the processing unit 80 determines that the kickback determination is unnecessary, and the process proceeds to S12. When the rotation speed of the brushless motor 22 is equal to or higher than the predetermined rotation speed (YES), the processing unit 80 determines that a kickback determination is necessary, and the process proceeds to S18.

In S18, the processing unit 80 specifies the amount of change ΔN of the rotation speed of the brushless motor 22 during the past predetermined period (for example, 32 ms). The amount of change ΔN in the rotation speed is specified by specifying the maximum value and the minimum value of the rotation speed of the brushless motor 22 during the past predetermined period, and taking the difference between the two.

In S20, the processing unit 80 determines whether or not the amount of change ΔN of the rotation speed specified in S18 exceeds a predetermined threshold value ΔNth. If ΔN exceeds ΔNth (YES), the process proceeds to S22.

In S22, the processing unit 80 determines whether or not the brushless motor 22 is decelerating. If the brushless motor 22 is decelerating (YES), the process proceeds to S24.

FIG. 4 shows a change over time in the rotation speed of the brushless motor 22 when kickback occurs in the brush cutter 10. When kickback occurs, the rotation speed of the brushless motor 22 drops sharply. Therefore, in the brush cutter 10 of the present embodiment, has kickback occurred based on the amount of change ΔN of the rotation speed of the brushless motor 22 between the current time t2 and the time t1 retroactive from the time t2 for a predetermined period? Judge whether or not. In the processing of S18, S20, and S22 of FIG. 3, when it is detected that the rotation speed of the brushless motor 22 suddenly decreases, the processing unit 80 determines that kickback has occurred and executes the processing of S24. ..

In S24, the processing unit 80 makes the switching elements 71, 72, 73 non-conducting, makes the switching elements 74, 75, 76 conductive, and applies a short-circuit brake to the brushless motor 22. As a result, the brushless motor 22 stops immediately without being accompanied by rotation due to inertia. After S24, the process proceeds to S26.

In S26, the processing unit 80 waits until the trigger 34 is turned off. When the trigger 34 is turned off (yes), the process returns to S2.

In S20, when ΔN is ΔNth or less (NO), and in S22, when the brushless motor 22 is not decelerating (NO), the process proceeds to S28.

In S28, the processing unit 80 specifies the amount of change Δθ of the posture angle of the brush cutter 10 during the past predetermined period (for example, 32 ms).

In S30, the processing unit 80 determines whether or not the amount of change Δθ of the posture angle of the brush cutter 10 exceeds a predetermined threshold value Δθth. If Δθ exceeds Δθth, the process proceeds to S24. When Δθ is Δθth or less, the process proceeds to S12.

FIG. 5 shows a change over time in the posture angle of the brush cutter 10 when a kickback occurs in the brush cutter 10. When kickback occurs, the posture angle of the brush cutter 10 changes abruptly. Therefore, in the brush cutter 10 of the present embodiment, has kickback occurred based on the amount of change Δθ of the posture angle of the brushless motor 22 between the current time t2 and the time t1 retroactive from the time t2 for a predetermined period? Judge whether or not. When it is detected that the posture angle of the brush cutter 10 has changed suddenly in the processes of S28 and S30 of FIG. 3, the processing unit 80 determines that kickback has occurred and executes the process of S24. A short-circuit brake is applied to the brushless motor 22.

As in the processes of S18, S20, and S22 of FIG. 3, the method of specifying the rotation speed of the brushless motor 22 using the output signal of the hall sensor 24 and determining the kickback from the decrease in the rotation speed of the brushless motor 22 , There is an advantage that the occurrence of kickback can be detected promptly. However, the decrease in the rotation speed when kickback occurs depends on the weight of the blade 12, and although the rotation speed is greatly reduced in the case of the light blade 12, the rotation speed is significantly reduced in the case of the heavy blade 12. do not. Therefore, when only the processing of S18, S20, and S22 is performed, the occurrence of kickback may not be detected when the heavy blade 12 is used.

On the other hand, as in the processes of S28 and S30 of FIG. 3, the blade 12 is used as a method of specifying the posture angle of the brush cutter 10 using the gyro sensor 52 and determining kickback from the change of the posture angle of the brush cutter 10. There is an advantage that the occurrence of kickback can be detected regardless of the weight of the kickback. However, in general, the response speed of the gyro sensor 52 is slower than the response speed of the hall sensor 24, so that if only the processes of S28 and S30 are performed, the occurrence of kickback may not be detected promptly.

In the brush cutter 10 of the present embodiment, the kickback is determined based on the decrease in the rotation speed of the brushless motor 22 due to the processing of S18, S20, and S22, and the posture angle of the brush cutter 10 is changed by the processing of S28 and S30. Perform both based kickback decisions. With such a configuration, the occurrence of kickback can be quickly detected based on the decrease in the rotation speed of the brushless motor 22, and the heavy blade 12 is used and the rotation speed does not decrease so much. Even so, the occurrence of kickback can be reliably detected based on the change in the posture angle of the brush cutter 10.

As described above, in one or more embodiments, the brush cutter 10 (example of a working machine) includes a blade 12 (an example of a working element) and a brushless motor 22 (an example of a driving unit) for driving the blade 12. And the rotation speed sensor 82 (example of the drive speed detection unit) that detects the rotation speed (example of the drive speed) of the brushless motor 22, and the posture that detects the amount of change in the attitude angle of the brush cutter 10 (example of the amount of movement). A processing unit 80 that brakes the brushless motor 22 when a predetermined condition related to the rotation speed of the brushless motor 22 and the amount of change in the attitude angle of the brush cutter 10 is satisfied with the angle sensor 84 (example of the motion state detection unit). (Example of braking part) is provided.

When kickback occurs in the brush cutter 10, the rotation speed of the brushless motor 22 drops sharply, and the posture angle of the brush cutter 10 changes significantly. According to the above configuration, since it is determined whether or not kickback has occurred by using both the rotation speed of the brushless motor 22 and the amount of change in the attitude angle of the brush cutter 10, the blade 12 is heavy and kickback is performed. Even when the rotation speed of the brushless motor 22 does not decrease so much when the above occurs, the occurrence of kickback can be reliably detected.

In one or more embodiments, the processing unit 80 brakes the brushless motor 22 when the first predetermined condition related to the rotational speed of the brushless motor 22 is met (S20, S22 in FIG. 3). (S24 in FIG. 3), the brushless motor 22 is also braked (S24 in FIG. 3) when the second predetermined condition related to the amount of change in the posture angle of the brush cutter 10 is satisfied (S30 in FIG. 3). ..

According to the above configuration, it is possible to determine whether or not a kickback has occurred under simplified conditions, so that a kickback can occur as compared with the case where the determination is made using complicated conditions. It can be detected quickly.

In one or more embodiments, the processing unit 80 determines whether or not the first predetermined condition is satisfied (S20, S22 in FIG. 3), and if the first predetermined condition is satisfied, brushless. The motor 22 is braked (S24 in FIG. 3), and when the first predetermined condition is not satisfied, it is determined whether or not the second predetermined condition is satisfied (S30 in FIG. 3), and the second predetermined condition is satisfied. When it is satisfied, the brushless motor 22 is braked (S24 in FIG. 3).

Generally, the response speed of the rotation speed sensor 82 that detects the rotation speed of the brushless motor 22 is faster than the response speed of the attitude angle sensor 84 that detects the amount of change in the attitude angle of the mowing machine 10. According to the above configuration, the occurrence of kickback can be detected more quickly by first determining the first predetermined condition using the rotation speed sensor 82 having a high response speed.

In one or more embodiments, the first predetermined condition is that the amount of change ΔN of the rotation speed of the brushless motor 22 in the first predetermined time exceeds the first threshold value ΔNth (S20 in FIG. 3). ), And the brushless motor 22 is decelerating (S22 in FIG. 3).

According to the above configuration, it is possible to quickly detect that the rotation speed of the brushless motor 22 has decreased due to the occurrence of kickback by a simple determination process.

In one or more embodiments, the second predetermined condition is that the amount of change Δθ of the posture angle of the brush cutter 10 in the second predetermined time exceeds the second threshold value Δθth (S30 in FIG. 3). Includes.

According to the above configuration, it is possible to quickly detect that the posture angle of the brush cutter 10 has changed with the occurrence of kickback by a simple determination process.

In one or more embodiments, the brushless motor 22 functions as a drive unit, and the rotation speed sensor 82 that detects the rotation speed of the brushless motor 22 functions as a drive speed detection unit.

According to the above configuration, the occurrence of kickback can be detected by using the rotation speed sensor 82 provided for controlling the rotation of the brushless motor 22.

In one or more embodiments, the attitude angle sensor 84 comprises a gyro sensor 52 that detects the angular velocity of the brush cutter 10.

According to the above configuration, the change in the posture angle of the brush cutter 10 can be detected by using the gyro sensor 52, and the occurrence of kickback can be reliably detected.

In one or more embodiments, the processing unit 80 brakes the brushless motor 22 with a short-circuit brake that modifies the wiring of the brushless motor 22.

According to the above configuration, the brushless motor 22 can be braked without separately providing a braking mechanism for mechanically braking the brushless motor 22.

In one or more embodiments, the brush cutter 10 comprises an operating paddle 30 and a handle 32 (an example of a grip) provided on the operating paddle 30. The blade 12 is provided at the tip of the operating paddle 30.

In the brush cutter 10 provided with the blade 12 at the tip of the operating pad 30, when kickback occurs, the force acting on the handle 32 becomes large. According to the above configuration, the occurrence of kickback can be reliably detected in such a brush cutter 10.

(Modification example)
In the above embodiment, the configuration in which the processing unit 80 completely stops the brushless motor 22 by the short-circuit brake when it is determined that the kickback has occurred has been described. Unlike this, the processing unit 80 may be configured to reduce the rotational speed of the brushless motor 22 when it is determined that kickback has occurred.

In the above embodiment, the processes of S28 and S30 of FIG. 3 may be performed first, and the processes of S18, S20 and S22 may be performed later.

In the above embodiment, in the process of S18 of FIG. 3, both the amount of change ΔN of the rotation speed of the brushless motor 22 and the amount of change Δθ of the posture angle of the brush cutter 10 in the past predetermined period are specified, and in S20 The threshold value ΔNth used in the determination process may be set according to the amount of change Δθ of the posture angle of the brush cutter 10. Alternatively, the threshold value Δθth used in the determination process of S30 may be set according to the amount of change ΔN of the rotation speed of the brushless motor 22.

In the above embodiment, the brush cutter 10 has described the configuration of detecting the rotation speed of the brushless motor 22 by using the hall sensor 24 provided in the brushless motor 22. Unlike this, the brush cutter 10 measures the currents flowing through the U-phase coil 22u, the V-phase coil 22v, and the W-phase coil 22w, respectively, and detects the rotation speed of the brushless motor 22 based on the respective current values. May be good.

In the above embodiment, the brush cutter 10 has described a configuration for determining whether or not kickback has occurred based on the rotation speed of the brushless motor 22. Unlike this, the brush cutter 10 may be configured to separately provide a rotation speed sensor for detecting the rotation speed of the blade 12 and detect the occurrence of kickback from the decrease in the rotation speed of the blade 12.

In the above embodiment, the brush cutter 10 describes a configuration in which the brushless motor 22 is braked by a so-called electric brake. Unlike this, even if the brush cutter 10 is provided with a so-called mechanical brake that mechanically brakes the brushless motor 22, and the processing unit 80 drives the mechanical brake to brake the brushless motor 22. Good.

In the above embodiment, the configuration in which the gyro sensor 52 detects the angular velocities of each of the three axes has been described, but the gyro sensor 52 has a direction in which the brush cutter 10 swings at least when kickback occurs, that is, the front unit 20 is rearward. It suffices if the angular velocity in the direction of moving to the right with respect to the unit 40 can be detected.

In the above embodiment, the configuration of the gyro sensor 52 provided in the rear unit 40 has been described. Unlike this, the gyro sensor 52 may be provided on the front unit 20, the handle 32, or the operating paddle 30.

In the above embodiment, the brush cutter 10 has described a configuration for determining whether or not kickback has occurred based on the amount of movement detected by the gyro sensor 52. Unlike this, the brush cutter 10 may be configured to determine whether or not kickback has occurred based on the amount of movement detected by the acceleration sensor. Alternatively, the brush cutter 10 uses a laser scanner or image recognition to identify the amount of movement of the brush cutter 10 with respect to the work or the surrounding environment, and determines whether or not kickback has occurred based on the specified amount of movement. You may judge.

In the above embodiment, the configuration in which the brush cutter 10 is operated by being supplied with electric power from the battery pack 44 has been described, but the brush cutter 10 is configured to operate by being supplied with electric power from an external power source via the power cord. May be good.

In the above embodiment, the configuration in which the brush cutter 10 drives the blade 12 using the brushless motor 22 as a drive source has been described, but the brush cutter 10 drives the blade 12 using a motor other than the brushless motor 22 as a drive source. It may be configured to be used. Alternatively, the brush cutter 10 may be configured to drive the blade 12 using another drive source such as an internal combustion engine.

In the above embodiment, the case where the working machine is the brush cutter 10 and the working element is the blade 12 has been described. In contrast, the work machine may be another work machine such as a chainsaw, mower, grinder, power cutter, etc., and the work element may be any work element used in the work machine. Good.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples illustrated above. The technical elements described herein or in the drawings exhibit their technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the techniques illustrated in the present specification or drawings can achieve a plurality of purposes at the same time, and achieving one of the purposes itself has technical usefulness.

10: Brushing machine 12: Blade 20: Front unit 22: Brushless motor 22u: U-phase coil 22v: V-phase coil 22w: W-phase coil 24: Hall sensor 26: Blade cover 30: Operating rod 30a: Front end 30b: Rear end 32 : Handle 32a: Right grip 32b: Left grip 34: Trigger 36: Direction selector 38: Electric cord 40: Rear unit 42: Constant voltage circuit 44: Battery pack 46: Break circuit 48: Speed dial 50: Power switch 52: Gyro sensor 61: First motor power line 62: Second motor power line 63: Third motor power line 64: Sensor power line 65: Sensor power line 66: Sensor signal line 67: Sensor signal line 68: Sensor signal line 70: Motor controller 71: Switching element 72: Switching element 73: Switching element 74: Switching element 75: Switching element 76: Switching element 78: Gate driver 80: Processing unit 82: Rotation speed sensor 84: Attitude angle sensor

Claims (9)

It ’s a work machine,
Working elements and
A drive unit that drives the work element,
A drive speed detection unit that detects the drive speed of the drive unit,
A movement amount detection unit that detects the movement amount of the work machine, and
A work machine comprising a braking unit that brakes the drive unit when predetermined conditions related to the drive speed of the drive unit and the movement amount of the work machine are satisfied. The braking part
When the first predetermined condition related to the driving speed of the driving unit is satisfied, the driving unit is braked.
The work machine according to claim 1, wherein the drive unit is braked even when the second predetermined condition related to the movement amount of the work machine is satisfied. The braking part
It is determined whether or not the first predetermined condition is satisfied, and
When the first predetermined condition is satisfied, the drive unit is braked and the drive unit is braked.
When the first predetermined condition is not satisfied, it is determined whether or not the second predetermined condition is satisfied.
The working machine according to claim 2, wherein the driving unit is braked when the second predetermined condition is satisfied. A claim that the first predetermined condition includes that the amount of change in the driving speed of the driving unit in the first predetermined time exceeds the first threshold value and the driving unit is decelerating. Item 2 or 3 working machine. The work machine according to any one of claims 2 to 4, wherein the second predetermined condition includes that the amount of movement of the work machine in a second predetermined time exceeds a second threshold value. The drive unit includes a motor and
The work machine according to any one of claims 1 to 5, wherein the drive speed detection unit includes a rotation speed sensor that detects the rotation speed of the motor. The work machine according to any one of claims 1 to 6, wherein the movement amount detection unit includes a gyro sensor that detects the angular velocity of the work machine. The working machine according to any one of claims 1 to 7, wherein the braking unit brakes the precursor driving unit by changing the connection of the driving unit. The working machine includes an operation paddle and a grip portion provided on the operation paddle.
The work machine according to any one of claims 1 to 8, wherein the work element is provided at the tip of the operation paddle.

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