Electric boring tool

• US 9,314,855 B2
• Filed: 02/01/2010
• Issued: 04/19/2016
• Est. Priority Date: 02/02/2009
• Status: Expired due to Fees

• Current Assignee: Hitachi KOKI Company Limited (Koki Holdings Co., Ltd.)
• Original Assignee: Hitachi KOKI Company Limited (Koki Holdings Co., Ltd.)
• Inventors: Ookubo, Takahiro, Iwata, Kazutaka
• Primary Examiner(s): Tecco, Andrew M
• Application Number:
  US13/147,492
• Publication Number:
  US 20110284255A1
• Time in Patent Office: 2,269 Days
• Field of Search: 173 1- 11, 173176-183, 227 1- 7
• US Class Current: 1/1
• CPC Class Codes: B23B 45/02 driven by electric power
• CPC Class Codes: B25D 16/006 Mode changers; Mechanisms connected thereto
• CPC Class Codes: B25D 2211/061 Swash-plate actuated impulse-driving mechanisms
• CPC Class Codes: B25D 2222/72 Stone, rock or concrete
• CPC Class Codes: B25D 2250/055 Depth properties, e.g. tools having depth indicator or depth control
• CPC Class Codes: B25D 2250/095 Electric motors
• CPC Class Codes: B25D 2250/201 for speed, e.g. drilling or percussion speed
• CPC Class Codes: B25D 2250/221 Sensors
• CPC Class Codes: B25D 2250/255 Switches
• CPC Class Codes: H02P 23/03 specially adapted for very low speeds
• CPC Class Codes: H02P 27/08 with pulse width modulation
• CPC Class Codes: H02P 6/06 Arrangements for speed regulation of a single motor wherein the motor speed is measured and compared with a given physical value so as to adjust the motor speed
• CPC Class Codes: Y02P 70/10 Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working

Abstract

An electric boring tool comprises an electric motor, a switch trigger, a tip tool driven by driving force of the electric motor, a power transmission mechanism for transmitting the driving force of the electric motor to the tip tool as rotational force and/or hammer force, and a motor control unit for controlling speed of the electric motor in response to an extent of pulling of the switch trigger. The motor control unit subjects the electric motor to low speed control after the electric motor is started up, and controls the speed of the electric motor in response to the extent of pulling of the switch trigger when the load current of the electric motor is set value or greater during the low speed control.

Claims

1. An electric boring tool comprising:

an electric motor;

a switch trigger;

a tip tool driven by driving force of the electric motor,

a power transmission mechanism for transmitting the driving force of the electric motor to the tip tool as rotational force and/or hammer force; and

a motor controller for controlling speed of the electric motor in response to an extent of pulling of the switch trigger,

wherein the motor controller subjects the electric motor to low speed control after the electric motor is started up even when the extent of pulling of the switch trigger is equal to or greater than a predetermined extent, the low speed control allowing the electric motor to rotate at a speed lower than a speed according to the predetermined extent, and controls the speed of the electric motor in response to the extent of pulling of the switch trigger when vibration or stress generated in the electric boring tool is a set value or greater during the low speed control.

2. The electric boring tool according to claim 1, wherein the motor controller comprises a setting unit capable of arbitrarily setting the set values for vibration and stress.

3. The electric boring tool according to claim 1, wherein the power transmission mechanism is a hammer drill mechanism having a switching mechanism for selecting one operation mode of at least a “

rotary-hammer mode”

, or a “

hammer mode”

for transmission to the tip tool.

4. The electric boring tool according to claim 1, wherein the motor controller comprises a soft release unit for releasing the automatic control for the low speed rotation.

5. The electric boring tool according to claim 1, wherein the electric motor comprises a brushless motor and the motor controller controls the speed of the electric motor by pulse-width-modulating a voltage applied to the electric motor in response to the extent of pulling of the switch trigger.

6. An electric tool comprising:

an electric motor;

a switch trigger;

a power transmission mechanism for transmitting driving force of the electric motor to a tip tool;

a motor controller connected to the switch trigger, the motor controller being configured to activate the electric motor upon operation on the switch trigger and to control speed of the electric motor; and

a soft-start switching switch connected to the motor controller, wherein in response to a state of the soft-start switching switch, whether or not to perform soft-start control by the motor controller is switched, the soft-start control controlling the electric motor to rotate at a low speed until the motor controller determines that loading on the tip tool is equal to or greater than a specified degree,

after the electric motor is activated.

7. The electric tool according to claim 6, further comprising a current detector that detects current flowing through the electric motor, wherein

the motor controller determines whether or not loading on the tip tool is equal to or greater than the specified degree, based on detection results of the current detector.

8. The electric tool according to claim 6, wherein, while the soft-start control is switched off or after the loading on the tip tool is determined to be equal to or greater than the specified degree during the soft-start control, the motor controller controls the speed of the electric motor in response to an extent of pulling of the switch trigger.