Engine-powered work tool provided with wind governor

Patent metadata

Field	Value
Publication number	US-9322344-B2
Application number	US-201414459027-A
Country	US
Kind code	B2
Filing date	Aug 13, 2014
Priority date	Aug 19, 2013
Publication date	Apr 26, 2016
Grant date	Apr 26, 2016

Abstract

An engine-powered work tool includes an engine having a crank shaft, an output controller and a wind governor. The output controller includes an output control shaft angularly rotatable about its axis for controlling a rotation speed of the crank shaft. The wind governor can control the angular rotation of the output control shaft and includes: a governor plate for receiving cooling air generated at a cooling fan connected to the crank shaft; an arm fixed to the output control shaft; and a governor spring connected to the arm for biasing the output control shaft to increase the rotation speed of the crank shaft. The governor plate functions to bias the output control shaft to decrease the rotation speed of the crank shaft upon receipt of the cooling air. The governor spring has an end changeable in position relative to the output controller among a plurality of prescribed positions.

First claim

What is claimed is:

1. An engine-powered work tool comprising:
an air-cooled engine including a crank shaft configured to rotate and a cooling fan fixed to the crank shaft and configured to rotate together with the crank shaft to generate cooling air;
an output controller configured to control a rotation speed of the crank shaft, the output controller including an output control shaft defining an axis and configured to make an angular rotation about the axis, the rotation speed of the crank shaft being controlled based on the angular rotation of the output control shaft; and
a wind governor configured to control the angular rotation of the output control shaft, the wind governor comprising:
a governor plate configured to receive the cooling air to apply a force to the output control shaft such that the rotation speed of the crank shaft decreases;
an arm fixed to the output control shaft; and
a governor spring configured to apply a biasing force to the output control shaft through the arm such that the rotation speed of the crank shaft increases, the governor spring having one end connected to the arm and another end changeable in position relative to the output controller among a plurality of prescribed positions, the position of the another end of the governor spring being switchable from one to another among the plurality of prescribed positions.

2. The engine-powered work tool as claimed in claim 1 , wherein the output controller includes a main body through which the output control shaft penetrates, the output control shaft having one end and another end opposite to each other; and
wherein the governor plate is fixed to the one end of the output control shaft and the governor spring is fixed to the another end of the output control shaft.

3. The engine-powered work tool as claimed in claim 1 , further comprising:
an air cleaner configured to introduce air into the output controller;
an air cleaner box attached to the output controller for covering the air cleaner; and
a mounting portion selectively attachable to the air clear box at one of a plurality of mounting positions corresponding to the plurality of prescribed positions, the another end of the governor spring being engaged with the mounting portion such that the position of the another end of the governor spring relative to the air cleaner box can be changed from one to another among the plurality of prescribed positions.

4. The engine-powered work tool as claimed in claim 3 , further comprising:
a handle to be gripped by an operator; and
a throttle wire having one end provided with an abutting portion configured to abut on the arm and another end connected to the handle, the abutment of the abutting portion with the arm causing the output control shaft to be biased in a direction to decrease the rotation speed of the crank shaft.

5. The engine-powered work tool as claimed in claim 4 , wherein the handle is provided with a throttle lever connected to the another end of the throttle wire, the operator's operation of the throttle lever at the handle enabling the abutting portion to abut on and separate from the arm.

6. The engine-powered work tool as claimed in claim 1 , further comprising:
a handle to be gripped by an operator; and
an adjustment wire having one end connected to the another end of the governor spring and another end provided at the handle, the position of the another end of the governor spring relative to the output controller being switchable from one to another among the plurality of prescribed positions in accordance with operations by the operator at the handle through the adjustment wire.

7. The engine-powered work tool as claimed in claim 6 , wherein the handle is provided with a switching dial connected to the another end of the adjustment wire, the operator's operations of the switching dial at the handle enabling the position of the another end of the governor spring to be switched from one to another among the plurality of prescribed positions.

8. The engine-powered work tool as claimed in claim 6 , further comprising a throttle wire having one end provided with an abutting portion configured to abut on the arm and another end connected to the handle, the abutment of the abutting portion with the arm causing the output control shaft to be biased in a direction to decrease the rotation speed of the crank shaft.

9. The engine-powered work tool as claimed in claim 8 , wherein the handle is provided with a throttle lever connected to the another end of the throttle wire, the operator's operation of the throttle lever at the handle enabling the abutting portion to abut on and separate from the arm.

10. The engine-powered work tool as claimed in claim 1 , further comprising:
a cutting blade configured to rotate in accordance with the rotation of the crank shaft; and
a supporting shaft having one end provided with the cutting blade and another end provided with the air-cooled engine, the output controller and the wind governor to constitute a brush cutter.

Assignees

• Hitachi Koki Kk

Inventors

• Isono toshiaki
• Akiba Genju

Classifications

• F01P1/02

  Arrangements for cooling cylinders or cylinder heads, e.g. ducting cooling-air from its pressure source to cylinders or along cylinders · CPC title

• A01D34/90

  for carrying by the operator · CPC title

• F02M35/1017

  Small engines, e.g. for handheld tools, or model engines; Single cylinder engines · CPC title

• F02D31/00 Primary

  Use of speed-sensing governors to control combustion engines, not otherwise provided for · CPC title

• F02B63/02

  for hand-held tools · CPC title