Electric working machine

Patent metadata

Field	Value
Publication number	US-9955627-B2
Application number	US-201314378734-A
Country	US
Kind code	B2
Filing date	Feb 15, 2013
Priority date	Feb 15, 2012
Publication date	May 1, 2018
Grant date	May 1, 2018

Abstract

An electric working machine including: a motor; a control unit configured to control rotation of the motor; a fixed part provided with a handle having a grip portion; a movable part held by the fixed part and is configured to be extendible by sliding relative to the fixed part; and a cutting blade provided to a end portion of the movable pipe and is configured to be driven by the motor; characterized in that the electric working machine further includes a detection unit which is connected to the control unit and is configured to detect whether or not the movable part is positioned at a predetermined extended position relative to the fixed part.

First claim

What is claimed is:

1. A handheld electric working machine comprising:
a motor;
a battery configured to supply power to the motor;
a control unit configured to control rotation of the motor;
a fixed part provided with a handle having a grip portion to be grabbed by a user so as to hold the electric working machine;
a movable part held by the fixed part and configured to change its position relative to the fixed part; and
a cutting blade provided to an end portion of the movable part and is configured to be driven by the motor;
wherein the movable part is configured to move between a first predetermined position at which a distance between the cutting blade and the grip portion of the fixed part is a first distance and a second predetermined position at which the distance between the cutting blade and the grip portion of the fixed part is a second distance longer than the first distance,
wherein the electric working machine further includes a detection unit which is connected to the control unit and is configured to detect whether the movable part is in the first predetermined position or the second predetermined position, and
wherein the detection unit includes an output unit configured to output a detection result signal, the control unit includes a reception unit configured to receive the detection result signal, and the control unit is configured to switch an electric circuit between the battery and the motor based on the received detection result signal.

2. The electric working machine according to claim 1 ,
wherein the control unit disallows the motor from being rotated when the movable part is positioned at the first predetermined position and allows the motor to be rotated when the movable part is positioned at the second predetermined position.

3. The electric working machine according to claim 2 ,
wherein the fixed part includes:
a housing provided with the control unit and a connection portion to which a power supply is configured to be connected;
a fixed pipe fixed to the housing; and
the handle provided to the fixed pipe, and

wherein the movable part is held to be slidable relative to the fixed pipe.

4. The electric working machine according to claim 2 , further comprising a trigger switch configured to allow rotation of the motor,
wherein, if the movable part is moved from the first predetermined position to the second predetermined position while the trigger switch is being pulled, the electric working machine continues to disallow the motor from being rotated.

5. The electric working machine according to claim 4 ,
wherein the control unit is configured to detect a pulling state of the trigger switch when a detection result by the detection unit indicates that the movable part has moved from the first predetermined position to the second predetermined position; and
wherein, when it is detected that the trigger switch is maintained in a pulled state, the control unit keeps the motor to be not allowed to be rotated until the trigger switch is released.

6. The electric working machine according to claim 5 ,
wherein, when detecting that the detection result by the detection unit indicates that the movable part has moved from the first predetermined position to the second predetermined position, the control unit keeps the motor to be not allowed to be rotated for a predetermined period of time regardless of the pulling state of the trigger switch.

7. The electric working machine according to claim 5 ,
wherein after keeping the motor to be not allowed to be rotated for the predetermined period of time, the control unit allows the motor to be rotated when release of the trigger switch is detected and the detection result by the detection unit indicates that the movable part is in the second predetermined position.

8. The electric working machine according to claim 1 ,
wherein the detection unit comprises a plurality of detection units, and
wherein, if outputs of the plurality of detection units do not coincide with each other, the control unit confirms an error and does not allow the motor to be rotated.

9. The electric working machine according to claim 1 ,
wherein the control unit is configured to not allow the motor to be rotated if an output from the detection unit indicating that the movable part is positioned at the second predetermined position has disappeared during rotation of the motor.

10. The electric working machine according to claim 1 ,
wherein a connection section is provided in the vicinity of an end portion of the fixed part and is configured to lock the fixed part and the movable part to prevent the fixed part and the movable part from being misaligned relative to each other in an axial direction thereof; and
wherein the detection unit is provided to the connection section.

11. The electric working machine according to claim 10 ,
wherein the fixed part includes:
a housing provided with the control unit;
a fixed pipe fixed to the housing; and
the handle provided to the fixed pipe, and

wherein the handle is fixed to the fixed pipe at a position between the connection section and the housing.

12. The electric working machine according to claim 1 ,
wherein the detection unit has a lever for detection; and
wherein a sleeve having a recess allowing the lever to be received therein is attached to the movable part.

13. The electric working machine according to claim 1 ,
wherein, when detecting that the detection result by the detection unit indicates that the movable part has moved from the second predetermined position to the first predetermined position during rotation of the motor, the control unit does not allow the motor to be rotated.

14. The electric working machine according to claim 1 ,
wherein, if the detection unit detects that the movable part has moved from the second predetermined position to the first predetermined position during rotation of the motor, a braking force is applied to the motor.

15. The electric working machine according to claim 1 , wherein the motor and the battery are physically connected to each other in both cases where the movable part is in the first predetermined position and the movable part is in the second predetermined position.

Assignees

• Hitachi Koki Kk

Inventors

• Nakano Yasushi
• Horie Yuki
• Funabashi Kazuhiko
• Toyoshima Yuuichi
• Ozawa Hiromi
• Tomita Hirohisa

Classifications

• A01D34/90

  for carrying by the operator · CPC title

• B25F5/02

  Construction of casings, bodies or handles {(B25F5/006, B25F5/008 take precedence)} · CPC title

• B25F3/00

  Associations of tools for different working operations with one portable power-drive means; Adapters therefor · CPC title

• Y10T83/541

  Actuation of tool controlled in response to work-sensing means · CPC title

• A01D34/828 Primary

  Safety devices · CPC title