Impact tool

Patent metadata

Field	Value
Publication number	US-2017246736-A1
Application number	US-201515523354-A
Country	US
Kind code	A1
Filing date	Sep 29, 2015
Priority date	Oct 29, 2014
Publication date	Aug 31, 2017
Grant date	—

Abstract

Provided is an impact tool which can perform control in accordance with working situations. The impact tool converts a torque of a brushless motor into a striking force and applies it to a tip tool. The impact tool includes: a motor control unit which makes detection about whether the tip tool is pressed against an object during the rotation of the brushless motor; and a motor control unit which performs speed increase control for increasing the rotational speed of the brushless motor when a state of pressing the tip tool against the object has been detected continuously for a predetermined time.

First claim

1 . An impact tool comprising:
a pressing detection unit that makes detection about whether a tip tool is pressed against an object during rotation of a motor; and a motor control unit that performs speed increase control for increasing a rotational speed of the motor when a state of pressing the tip tool against the object has been detected continuously for a predetermined time.

2 . The impact tool according to claim 1 , further comprising a target rotational speed setting unit that sets a target rotational speed for the motor,
wherein the motor control unit performs the speed increase control for making the rotational speed of the motor higher than the target rotational speed when the state of pressing the tip tool against the object has been detected continuously for the predetermined time while the rotational speed of the motor is controlled based on the target rotational speed.

3 . The impact tool according to claim 2 ,
wherein the motor control unit performs the speed increase control when the target rotational speed setting unit selects a maximum settable as the target rotational speed, and performs control for setting the rotational speed of the motor to the target rotational speed without performing the speed increase control when the target rotational speed setting unit selects a value less than the maximum settable as the target rotational speed.

4 . The impact tool according to claim 1 , further comprising: a casing that holds the tip tool; and a handle that is gripped by a hand of an operator and operated in directions approaching and separated from the casing,
wherein the pressing detection unit determines that the tip tool is pressed against the object when the handle is operated in the direction approaching the casing.

5 . The impact tool according to claim 1 , further comprising:
a casing that holds the tip tool; and a striking mechanism that is provided in the casing and converts the torque of the motor into a striking force, wherein the striking mechanism comprises:
a piston that reciprocates by transmission of power of the motor;
a cylinder that reciprocally houses the piston;
an air chamber that is formed in the cylinder and generates a striking force using a reciprocating operation of the piston;
a striking element that is housed in the cylinder and applies a striking force generated by the air chamber to the tip tool;
an idle striking preventing hole that is formed by penetrating through the cylinder and communicates with the air chamber; and
a closing member that is provided movably in a direction along a central line of the cylinder,
the closing member closes the idle striking preventing hole when the tip tool is pressed against the object, and opens the idle striking preventing hole when the tip tool is separate from the object, and the pressing detection unit determines that the tip tool is pressed against the object when the closing member closes the idle striking preventing hole.

6 . The impact tool according to claim 1 , further comprising:
a torque transmission mechanism that transmits the torque of the motor to the tip tool; and a working mode switching mechanism that switches from one of a rotating/striking mode and a striking mode to the other, the rotating/striking mode applying the striking force to the tip tool and transmitting the torque to the tip tool, the striking mode applying the striking force to the tip tool without transmitting the torque to the tip tool, wherein the motor control unit performs the speed increase control based on a detection result obtained by the pressing detection unit when the striking mode is selected, and does not perform the speed increase control regardless of the detection result obtained by the pressing detection unit when the rotating/striking mode is selected.

7 . The impact tool according to claim 2 ,
wherein when the target rotational speed setting unit sets a new target rotational speed during execution of the speed increase control, the motor control unit finishes the speed increase control and controls the rotational speed of the motor based on the new target rotational speed.

8 . The impact tool according to claim 5 ,
wherein the motor control unit stops the motor when a state in which the closing member opens the idle striking preventing hole has been detected continuously for a predetermined time.

Assignees

• Hitachi Koki Kk

Inventors

• Kikuchi Atsuyuki

Classifications

• B25D2250/201

  for speed, e.g. drilling or percussion speed · CPC title

• B25D11/04

  in which the tool bit or anvil is hit by an impulse member · CPC title

• B25D2216/0023

  Tools having a percussion-and-rotation mode · CPC title

• B25D16/00 Primary

  Portable percussive machines with superimposed rotation {, the rotational movement of the output shaft of a motor being modified to generate axial impacts on the tool bit (combined percussion and rotary drilling adapted for earth drilling E21B6/00)} · CPC title

• B25D11/005

  Arrangements for adjusting the stroke of the impulse member or for stopping the impact action when the tool is lifted from the working surface · CPC title