JP2014066198A - Power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an improvement technology regarding a recoil starter in a power tool having an engine and a motor.SOLUTION: A bush cutter is configured as a power tool having an engine 311 and an electric motor 341. The bush cutter includes a controller for controlling the electric motor 341, a recoil starter 400 for starting-up the engine 311, a battery pack 337 for driving the electric motor 341 and a head gear driven by the engine 311. Therein, the bush cutter is configured so as to drive a cutting blade attachably and detachably mounted to the head gear. Further, the controller performs control so as to drive the electric motor 341 when the recoil starter 400 is driven. Furthermore, a piston 315 is caused to slide by a drive of the recoil starter 400 and a drive of the electric motor 341 and is configured so as to start-up the engine 311.

Description

  The present invention relates to a power tool for driving a tip tool.

  Japanese Patent Application Laid-Open No. 2008-180144 describes a recoil starter for starting an engine. It is comprised so that the rotational force of a rope reel can be stored in a power storage spring. And it is comprised so that an engine may be started by rotating the crankshaft of an engine with the rotational force of an accumulation spring, and the rotational force of a rope reel.

JP 2008-180144 A

  By the way, in the recoil starter described in Japanese Patent Application Laid-Open No. 2008-180144, it is necessary to pull the rope reel a plurality of times in order to store the rotational force in the energy storing spring, and the engine starting operation becomes complicated. Then, an object of this invention is to provide the improvement technique regarding a recoil starter in the power tool which has an engine and a motor.

  In order to solve the above problems, according to a preferred embodiment of the power tool according to the present invention, a power tool having an engine and a motor is configured. The power tool includes a controller for controlling the motor, a recoil starter for starting the engine, a battery for driving the motor, and a drive shaft driven by the engine. The power tool is configured to drive a tip tool that is detachably attached to the drive shaft. Further, the controller controls the motor so as to drive the motor when the recoil starter is driven. The engine is started by sliding the piston of the engine by driving the recoil starter and the motor.

  According to the present invention, the engine can be started by driving both the recoil starter and the motor. As a result, the motor assists the drive of the recoil starter, so that the burden for the user to drive the recoil starter can be reduced as compared with the case where the user starts the engine only by the recoil starter.

  According to the further form of the power tool which concerns on this invention, it has a starter switch for starting an engine. The controller controls the motor to drive as a cell motor that starts the engine when the starter switch is operated. The engine is started only by driving the motor. “Motor drive only” means that the engine is started by driving the motor without requiring driving of the recoil starter.

  According to this embodiment, it is not necessary to provide a separate cell motor for starting the engine by operating the starter switch. Therefore, the power tool can be reduced in size.

  According to the further form of the power tool which concerns on this invention, a drive shaft is comprised so that it may drive simultaneously with an engine and a motor, and may drive a tip tool.

  According to this embodiment, a so-called hybrid power tool in which the tip tool is driven by the engine and the motor can be configured.

  According to the further form of the power tool which concerns on this invention, while the recoil starter is connected with one edge part of the crankshaft of an engine, the motor is connected with the other edge part of the crankshaft. And the recoil starter is connected with the rotating shaft of the motor, and is comprised so that a rotating shaft can be rotated.

  According to this embodiment, the recoil starter and the motor are arranged at both ends of the crankshaft, so that the crankshaft can be stably rotated when the recoil starter is driven.

  According to the further form of the power tool which concerns on this invention, the motor is comprised so that a piston may be driven in the compression process which a piston goes to a top dead center from a bottom dead center. On the other hand, the motor is configured to be driven by the engine and charge a battery as a generator in a process other than the compression process.

  According to this embodiment, the motor can be used as a generator without providing a separate generator. Therefore, the power tool can be reduced in size.

  According to the further form of the power tool which concerns on this invention, it has a sensor which detects the rotational speed of the crankshaft of an engine. The controller is configured to control the rotational speed of the motor based on the rotational speed of the crankshaft detected by the sensor when the recoil starter is driven.

  According to this embodiment, the rotational speed of the motor can be controlled based on the user force applied to the recoil starter, that is, the rotational speed of the crankshaft. As a result, the motor can be driven without exceeding the rotational speed of the crankshaft by the recoil starter. Therefore, the motor can assist the drive of the recoil starter appropriately.

  ADVANTAGE OF THE INVENTION According to this invention, the improvement technique regarding a recoil starter can be provided in the power tool which has an engine and a motor.

It is a perspective view showing the whole power tool composition concerning an embodiment of the present invention. It is sectional drawing of the main-body part of a power tool. It is a rear view of the main-body part of a power tool. It is a block diagram which shows the drive system of a power tool.

  An embodiment of the present invention will be described in detail with reference to FIGS. This embodiment is described using a brush cutter as an example of a power tool. As shown in FIG. 1, the brush cutter 1 is mainly composed of an operating rod 2, a power unit 3, a gear head 4, and a handle 7. The operating rod 2 is a hollow pipe member, inside which a drive shaft 355 (see FIG. 2) is arranged. The power unit 3 is disposed at the rear end of the operation rod 2. The gear head 4 is arrange | positioned at the front-end part of the operating rod 2, and the cutting blade 5 is comprised so that attachment or detachment is possible. A safety cover 6 is disposed at the front end of the operation rod 2 so as to partially cover the cutting blade 5. Further, the handle 7 is disposed in the middle part of the operation rod 2. The handle 7 is provided with a throttle lever 8 and a start switch 9 connected to the power unit 3.

  As shown in FIG. 2, the main body 2 mainly includes a main body housing 301, a battery housing portion 360, and a recoil starter 400. The main body housing 301 forms an outline of the power unit 3. The battery accommodating part 360 is arrange | positioned at the front side (right side of FIG. 2) of the main body housing 301, and is comprised so that the battery pack 337 may be mounted | worn so that attachment or detachment is possible. The recoil starter 400 is disposed on the rear side (left side in FIG. 2) of the power unit 3.

  As shown in FIG. 2, the drive mechanism 310 is accommodated in the main body housing 301. The drive mechanism unit 310 is mainly composed of an engine 311 and an electric motor 341. The drive mechanism 310 is configured such that the outputs of both the engine 311 and the electric motor 341 are transmitted to the gear head 4 via the drive shaft 355. Accordingly, the gear head 4 is configured to rotate the cutting blade 5. That is, the cutting blade 5 is configured as a hybrid power tool driven by an engine 311 and two electric motors 341 that are two different types of prime movers.

  The engine 311 is configured as a reciprocating engine, and mainly includes a cylinder 313, a piston 315, a spark plug 317, a crankcase 319, a crankshaft 323, and a connecting rod 325. The piston 315 is slidably disposed in the cylinder 313. The spark plug 317 is disposed in the cylinder 313 above the piston 315. The crankcase 319 is connected to the cylinder 313 and is disposed below the cylinder 313. The crankshaft 323 is rotatably supported by the bearing and is disposed in the crankcase 319. The connecting rod 325 connects the piston 315 and the crankshaft 323. This engine 311 is an implementation configuration example corresponding to the “engine” in the present invention.

  The crankshaft 323 is arranged so as to extend in parallel with the extending direction of the drive shaft 355 (left-right direction in FIG. 2). A recoil starter 400 is disposed on one side of the crankshaft 323 (left side in FIG. 2). On the other hand, an electric motor 341 is disposed on the other side (right side in FIG. 2) of the crankshaft 323.

  The electric motor 341 is configured as an outer rotor type motor, and is arranged coaxially with the crankshaft 323. The electric motor 341 is mainly composed of a stator core 343, a stator coil 345, an outer rotor 347, and a magnet 349. The stator core 343 is a disk-shaped member made of a magnetic material. The stator core 343 is fixed to the outer surfaces of the cylinder 313 and the crankcase 319 via a sleeve 343a. That is, the crankshaft 323 is inserted into the sleeve 343a, and the crankshaft 323 is rotatably arranged with respect to the stator core 343 fixed thereby. The stator coil 345 is wound around the stator core 343 and excites the stator core 343 when energized.

  The outer rotor 347 is a substantially cylindrical member, and is fixed to the crankshaft 323 so as to rotate integrally with the crankshaft 323. The magnet 349 is disposed on the inner peripheral surface of the outer rotor 347 so as to face the outer peripheral surface of the stator core 343. The outer rotor 347 is connected to the centrifugal clutch 351 via the connecting rod 348, and thus the outer rotor 347 and the centrifugal clutch 351 are configured to rotate integrally. Further, a clutch drum 353 is disposed outside the centrifugal clutch 351. When the centrifugal clutch 351 rotates, the centrifugal clutch 351 and the clutch drum 353 are engaged by centrifugal force, and the rotation of the engine 311 and the electric motor 341 is transmitted to the clutch drum 353. That is, the clutch drum 353 is configured to rotate integrally with the centrifugal clutch 351 when the rotational speed of the centrifugal clutch 351 exceeds a predetermined rotational speed. The clutch drum 353 is connected to the gear head 4 via the drive shaft 355. Thereby, the outputs of the engine 311 and the electric motor 341 are transmitted to the gear head 4, and the cutting blade 5 is rotated to perform a predetermined operation. This electric motor 341 is an implementation configuration example corresponding to the “motor” in the present invention. The gear head 4 is an implementation configuration example corresponding to the “drive shaft” in the present invention.

  As shown in FIGS. 2 and 3, the recoil starter 400 is mainly configured by a case 401, a recoil starter handle 402, a recoil rope 403, and a rope reel 404. As shown in FIG. 4, the recoil starter 400 is provided with a sensor 410 that detects that the recoil rope 403 has been pulled. This sensor 410 is connected to the controller 339. The recoil starter 400 is connected to the crankshaft 323 via a coupling 370. Accordingly, the engine 311 is started by rotating the crankshaft 323 by pulling the recoil rope 403. The detailed structure of the recoil starter 400 will not be described for the sake of convenience. The recoil starter 400 is an implementation configuration example corresponding to the “recoil starter” in the present invention.

  The recoil starter 400 is connected to the outer rotor 347 of the electric motor 341 via the coupling 370 and the crankshaft 323. The coupling 370 is configured to rotate the crankshaft 323 when the rope reel 404 is rotated by pulling the recoil rope 403. On the other hand, the coupling 370 is configured such that when the rope reel 404 is stopped, the rope reel 404 is not rotated even if the crankshaft 323 is rotated. That is, the coupling 370 is configured as a one-way clutch.

  As shown in FIG. 4, the controller 339 is configured to control the electric motor 341 and the like. That is, the controller 339 sequentially supplies current from the battery pack 337 to the stator coil 345 based on the detection result of a position sensor (not shown) that detects the position of the outer rotor 347, and rotates the outer rotor 347. Thereby, the rotation speed of the electric motor 341 is controlled. On the other hand, by operating the throttle lever 8, the intake air amount of the engine 311 or the mixture ratio of fuel and air is adjusted based on the operation amount of the throttle lever 8. Thereby, the rotation speed of the engine 311 is controlled. Since the throttle lever 8 is also connected to the controller 339, the controller 339 may be configured to adjust the intake amount of the engine 311 or the mixture ratio of the air-fuel mixture.

  Further, the controller 339 is connected to the start switch 9, the sensor 410, and the battery pack 337. Thus, when starting the engine 311, the controller 339 is configured to control the motor 341 based on the operation of the start switch 9 and the detection result of the sensor 410.

  When the engine 311 is started using the recoil starter 400, the recoil starter 400 rotates the crankshaft 323 to move the piston 315 toward the top dead center. Thereby, the air-fuel mixture in the cylinder 313 is compressed. Then, by igniting the spark plug 317, the compressed air-fuel mixture is exploded and the engine 311 is started. At this time, the user needs to pull the recoil rope 403 with a large force in order to compress the air-fuel mixture. That is, the engine 311 cannot be started unless the recoil rope 403 is operated with a large force.

  Therefore, in this embodiment, when the sensor 410 detects that the recoil starter handle 402 has been operated by the user and the recoil rope 403 has been pulled, the controller 339 controls the electric motor 341 to rotate the crankshaft 323. To do. Specifically, in the compression process in which the piston 315 moves toward the top dead center, the controller 339 controls the electric motor 341 to rotate the crankshaft 323. At this time, the rotation speed of the electric motor 341 is controlled so as not to exceed the rotation speed of the recoil rope 403. That is, the electric motor 341 assists the rotation of the crankshaft 323, thereby reducing the force with which the user pulls the recoil rope 403.

  On the other hand, when the start switch 9 is operated to start the engine 311, the controller 339 drives the electric motor 341 to rotate the crankshaft 323 so that the air-fuel mixture in the cylinder 313 is compressed. Thereafter, the controller 339 ignites the spark plug 317 and starts the engine 311. That is, the electric motor 341 is used as a cell motor for starting the engine 311.

  Further, as shown in FIG. 4, a mode changeover switch 336 is connected to the controller 339. The mode changeover switch 336 is configured to be manually operable by the user. After the engine 311 is started, the controller 339 switches the drive mode of the brush cutter 1 between the first and second modes based on the mode selected by the mode switch 336. That is, in the first mode, the cutting blade 5 is driven by the engine 311 and the electric motor 341. In the second mode, the cutting blade 5 is driven only by the engine 311.

  When the first mode is selected, when the throttle lever 8 is operated, the engine 311 and the electric motor 341 are driven simultaneously. When the rotational speed of the outer rotor 347 exceeds a predetermined rotational speed, the centrifugal clutch 351 is activated and the rotation of the outer rotor 347 is transmitted to the clutch drum 353. That is, the rotation of the engine 311 and the electric motor 341 is transmitted to the clutch drum 353. As a result, the drive shaft 355 is driven by the engine 311 and the electric motor 341. As a result, the gear head 4 is driven by the drive shaft 355. That is, the brush cutter 1 drives the cutting blade 5 by driving both the engine 311 and the electric motor 341.

  In the first mode, the controller 339 controls the electric motor 341 to rotate the crankshaft 323 in the compression process in which the piston 315 moves toward the top dead center. That is, in the compression process, the cutting blade 5 is driven by driving both the engine 311 and the electric motor 341. On the other hand, in the steps other than the compression step, the outer rotor 347 is rotated by the rotation (inertia force) of the crankshaft 323, whereby the electric motor 341 is configured to charge the battery pack 337 as a generator. It should be noted that the controller 339 may drive the electric motor 341 and drive the cutting blade 5 by driving both the engine 311 and the electric motor 341 also in steps other than the compression step.

  When the second mode is selected, when the throttle lever 8 is operated, only the engine 311 is driven. When the rotational speed of the outer rotor 347 connected to the crankshaft 323 exceeds a predetermined rotational speed, the centrifugal clutch 351 is activated and the rotation of the crankshaft 323 is transmitted to the clutch drum 353. As a result, the engine 311 drives the drive shaft 355 via the outer rotor 347 and the clutch drum 353. As a result, the gear head 4 is driven by the drive shaft 355. That is, the brush cutter 1 drives the cutting blade 5 by driving only the engine 311. In the second mode, the electric motor 341 operates as a generator by rotating the outer rotor 347. A current is supplied to the battery pack 337 from an electric motor 341 as a generator via a controller 339. Thereby, the battery pack 337 is charged.

  According to the present embodiment described above, when the engine 311 is started using the recoil starter 400, the electric motor 341 assists the rotation of the crankshaft 323, thereby reducing the force with which the user pulls the recoil rope 403. Can do. As a result, the engine 311 can be started without requiring a large force.

  Further, according to the present embodiment, the outer rotor 347 of the electric motor 341 can be rotated by pulling the recoil rope 403 and rotating the rope reel 404. Thereby, the rotating member is arrange | positioned at the both ends of the crankshaft 323, and when starting the engine 311 by the recoil starter 403, the crankshaft 323 can be rotated stably.

  Moreover, according to this embodiment, when the electric motor 341 does not drive the cutting blade 5, the electric motor 341 can be used as a generator. That is, it is not necessary to provide both the electric motor 341 and the generator in the brush cutter 1, and the brush cutter 1 is reduced in weight and size.

  Moreover, according to this embodiment, the cutting blade 5 can be driven by selecting the first and second modes. Therefore, the output of the brush cutter 1 can be switched by switching the drive mode according to the load acting on the cutting blade 5. As a result, energy efficiency can be increased.

  Further, according to the present embodiment, since the outer rotor type motor is provided as the electric motor 341, a large output torque can be obtained without increasing the size of the electric motor 341. That is, the distance (radius) from the rotation center of the outer rotor 147 to the outer periphery can be increased, and thereby a large output torque can be obtained. As a result, the brush cutter 1 is reduced in size.

  In the above, the controller 339 may drive the electric motor 341 again when the piston 315 cannot pass through the top dead center first after the engine 311 is started. Thereby, the electric motor 341 assists the crankshaft 323, so that the electric motor 341 can fulfill the function of a flywheel.

  In the above description, the sensor 410 detects that the recoil rope 403 has been pulled. However, the present invention is not limited to this. For example, it may be detected that the recoil rope 403 is pulled by using a position sensor that detects the position of the outer rotor 347. When the recoil rope 403 is pulled, the outer rotor 347 is rotated via the crankshaft 323. Therefore, by using a position sensor that detects the position of the outer rotor 347, the sensor 410 becomes unnecessary.

  In the above description, the electric motor 341 is provided with an outer rotor type motor, but is not limited thereto, and an inner rotor type motor may be used. Further, the centrifugal clutch 351 can be changed to an electromagnetic clutch.

  Moreover, in the above, it was comprised so that the cutting blade 5 might be driven by 1st mode or 2nd mode, However, It is not restricted to this. For example, the brush cutter 1 only needs to have the first mode, and does not have to have the second mode.

  Moreover, in the above, although demonstrated using the brush cutter 1 as a power tool, this invention is also applicable to another power tool. If it has an engine and a motor, this invention can also be applied to power tools, such as a chain saw, a hammer drill, and a circular saw.

(Correspondence between each component of the embodiment and each component of the present invention)
This embodiment shows an example for carrying out the present invention. Therefore, the present invention is not limited to the configuration of the present embodiment. The correspondence between each component of the present embodiment and each component of the present invention is shown below.
The brush cutter 1 is an example of a configuration corresponding to the “power tool” of the present invention.
The gear head 4 is an example of a configuration corresponding to the “drive shaft” of the present invention.
The start switch 9 is an example of a configuration corresponding to the “starter switch” of the present invention.
The engine 311 is an example of a configuration corresponding to the “engine” of the present invention.
The crankshaft 323 is an example of a configuration corresponding to the “crankshaft” of the present invention.
The battery pack 337 is an example of a configuration corresponding to the “battery” of the present invention.
The controller 339 is an example of a configuration corresponding to the “controller” of the present invention.
The electric motor 341 is an example of a configuration corresponding to the “motor” of the present invention.
The recoil starter 400 is an example of a configuration corresponding to the “recoil starter” of the present invention.
The sensor 410 is an example of a configuration corresponding to the “sensor” of the present invention.

In view of the gist of the above invention, the working tool according to the present invention can be configured in the following manner.
(Aspect 1)
“A power tool according to claim 1,
Regarding the direction in which the crankshaft of the engine extends,
The power tool, wherein the engine is disposed between the recoil starter and the motor. "

DESCRIPTION OF SYMBOLS 1 Brush cutter 2 Operation rod 3 Power unit 4 Gear head 5 Cutting blade 6 Safety cover 7 Handle 8 Throttle lever 9 Start switch 301 Main body housing 310 Drive mechanism 311 Engine 313 Cylinder 315 Piston 317 Spark plug 319 Crankcase 323 Crankshaft 325 Connecting rod 336 Mode changeover switch 337 Battery pack 339 Controller 341 Electric motor 343 Stator core 343a Sleeve 345 Stator coil 347 Outer rotor 348 Connection rod 349 Magnet 351 Centrifugal clutch 353 Clutch drum 355 Drive shaft 360 Battery housing 370 Coupling 400 Recoil starter 401 Case 402 Recoil starter Handle 403 Recoil rope 404 Rope reel 41 Sensor

Claims (6)

An engine, a motor,
A controller for controlling the motor;
A recoil starter for starting the engine;
A battery for driving the motor;
A power tool having a drive shaft driven by the engine and driving a tip tool detachably attached to the drive shaft;
The controller controls the motor to drive the motor when the recoil starter is driven;
A power tool configured to start the engine by sliding a piston of the engine by driving the recoil starter and driving the motor. The power tool according to claim 1,
A starter switch for starting the engine;
The controller controls the motor to drive as a cell motor that starts the engine when the starter switch is operated;
A power tool configured to start the engine only by driving the motor. The power tool according to claim 1 or 2,
The power tool is configured such that the drive shaft is driven simultaneously by the engine and the motor to drive the tip tool. The power tool according to any one of claims 1 to 3,
The recoil starter is connected to one end of the crankshaft of the engine, and the motor is connected to the other end of the crankshaft,
The power tool characterized in that the recoil starter is connected to a rotating shaft of the motor and is configured to be able to rotate the rotating shaft. The power tool according to any one of claims 1 to 4,
The motor is
The piston is configured to drive the piston in a compression process from bottom dead center to top dead center,
In a process other than the compression process, the power tool is configured to be driven by the engine and charge the battery as a generator. The power tool according to any one of claims 1 to 5,
A sensor for detecting a rotational speed of the crankshaft of the engine;
The controller is configured to control the rotational speed of the motor based on the rotational speed of the crankshaft detected by the sensor when the recoil starter is driven. tool.

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