ELECTRIC BORING TOOL

• US 20110284255A1
• Filed: 02/01/2010
• Published: 11/24/2011
• Est. Priority Date: 02/02/2009
• Status: Active Grant

• 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
• Granted Patent: US 9,314,855 B2
• Time in Patent Office: Days
• US Class Current: 173/109
• 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 control unit for controlling speed of the electric motor in response to an extent of pulling of the switch trigger,

characterized in that 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.

2. The electric boring tool according to claim 1, wherein the motor control unit comprises a setting unit capable of arbitrarily setting the set values for the motor load current.

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 control unit comprises a soft release unit for releasing the automatic control for the low speed rotation.

9. The electric boring tool according to claim 1, wherein the electric motor comprises a brushless motor and the motor control unit 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.

5. 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 control unit for controlling speed of the electric motor in response to an extent of pulling of the switch trigger,

characterized in that 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 vibration or stress generated in the electric boring tool are set values or greater during the low speed control.

6. The electric boring tool according to claim 5, wherein the motor control unit comprises a setting unit capable of arbitrarily setting the set values for vibration and stress.

7. The electric boring tool according to claim 5, 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.

8. The electric boring tool according to claim 5, wherein the motor control unit comprises a soft release unit for releasing the automatic control for the low speed rotation.

10. The electric boring tool according to claim 5, wherein the electric motor comprises a brushless motor and the motor control unit 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.