ROTARY IMPACT TOOL

• US 20110315417A1
• Filed: 01/14/2010
• Published: 12/29/2011
• Est. Priority Date: 03/10/2009
• Status: Active Grant

• Current Assignee: Makita Corporation
• Original Assignee: Makita Corporation
• Inventors: Matsunaga, Yutaka, Yamamoto, Hirokatsu, Hayashi, Katsuna, Ichikawa, Yoshitaka
• Granted Patent: US 8,678,106 B2
• Time in Patent Office: Days
• US Class Current: 173/176
• CPC Class Codes: B25B 21/008 with automatic change-over from high speed-low torque mode to low speed-high torque mode
• CPC Class Codes: B25B 21/02 with means for imparting impact to screwdriver blade or nut socket
• CPC Class Codes: B25B 21/026 Impact clutches
• CPC Class Codes: B25B 23/14 Arrangement of torque limiters or torque indicators in wrenches or screwdrivers couplings for transmitting rotation or clutches F16D; devices for measuring torque per se G01L
• CPC Class Codes: B25B 23/147 specially adapted for electrically operated wrenches or screwdrivers

Abstract

A rotary impact tool includes: a hammer rotating by receiving a rotational force of a motor; an anvil rotating by receiving a rotational force of the hammer; and an end tool attached to the anvil, the rotary impact tool being constructed such that when a torque of a value not less than a predetermined value is applied to the anvil from the outside, the hammer is disengaged from the anvil to rotate idle and applies an impact to the anvil in a rotational direction after rotating idle by a predetermined angle, the rotary impact tool including an impact detection means detecting impacts and a speed switching means switching the rotational speed of the motor, and when the impact detection means detects an impact during rotation of the anvil in a tightening direction, the speed switching means switches the rotational speed of the motor from a normal speed to a low speed.

Claims

1-5. -5. (canceled)

6. A rotary impact tool comprising:

a hammer configured to rotate by receiving a rotational force of a motor;

an anvil configured to rotate by receiving a rotational force of the hammer;

an end tool attached to the anvil;

wherein when a torque of a value not less than a predetermined value is applied to the anvil from the outside, the hammer is disengaged from the anvil to rotate idle and applies an impact to the anvil in a rotational direction after rotating idle by a predetermined angle;

an impact detection device configured to detect impacts; and

a speed switching device configured to switch the rotational speed of the motor,

wherein when the impact detection device detects start of impact during rotation of the anvil in a tightening direction, the speed switching device switches the rotational speed of the motor from a normal speed to a low speed.

7. The rotary impact tool according to claim 6, further comprising a speed adjusting mechanism capable of adjusting between 0 and a predetermined value a difference between the normal speed and the low speed.

8. The rotary impact tool according to claim 6, further comprising a main switch configured to adjust the rotating speed of the motor according to a pulling amount of a trigger, wherein:

both in the case that the motor is switched to the normal speed and in the case that the motor is switched to the low speed, the rotational speed of the motor can be adjusted according to the pulling amount of the trigger.

9. The rotary impact tool according to claim 6, wherein the impact detection device comprises one of a piezoelectric sensor and an acceleration sensor.

10. The rotary impact tool according to claim 6, wherein during the rotation of the anvil in a direction opposite to the tightening direction, the speed switching device does not switch the rotational speed of the motor even in the case that the impact detection device detects an impact.