Easy engine starting system

Patent metadata

Field	Value
Publication number	US-12577929-B2
Application number	US-202118554632-A
Country	US
Kind code	B2
Filing date	Apr 26, 2021
Priority date	Apr 26, 2021
Publication date	Mar 17, 2026
Grant date	Mar 17, 2026

Abstract

Provided is an easy engine starting system including: an engine; a centrifugal clutch configured to transmit a driving force of the engine to a driven device; and a control device configured to adjust output of the engine. When the engine is to be started, the engine is accelerated at start engine output which enables the engine to reach a rotation speed higher than a clutch-in rotation speed. The control device has suppression control of suppressing, at the start engine output, the rotation speed to a rotation speed equal to or lower than the clutch-in rotation speed.

First claim

The invention claimed is:

1 . An easy engine starting system, comprising:
an engine having a carburetor; a centrifugal clutch configured to transmit a driving force of the engine to a driven device; and a control device configured to adjust output of the engine, wherein, when the engine is to be started, the engine is accelerated, using control by the carburetor of an air-fuel mixture that flows into the engine, at start engine output which enables the engine to reach a rotation speed higher than a clutch-in rotation speed, wherein the control device is configured to control the engine in a start mode, a first start-time PI control step that follows the start mode, and a second start-time PI control step that follows the first start-time PI control step, and wherein the control device is configured to transition from the start mode to the first start-time PI control step based on a number of engine rotations, and wherein the control device is configured to transition from the first start-time PI control step to the second start-time PI control step based on a temperature of the engine.

2 . The easy engine starting system according to claim 1 , wherein the carburetor includes a throttle valve configured to adjust the air-fuel mixture supplied to a combustion chamber of the engine,
wherein, at the start engine output, a throttle opening degree of the throttle valve is adjusted so as to enable the engine to reach a rotation speed higher than the clutch-in rotation speed.

3 . The easy engine starting system according to claim 2 , wherein the output of the engine is from 0.5 kW to 2 kW, and the throttle opening degree has a target corresponding to a rotation speed equal to or higher than the clutch-in rotation speed and equal to or lower than twice of the clutch-in rotation speed.

4 . The easy engine starting system according to claim 3 , wherein the throttle opening degree has a target corresponding to a rotation speed equal to or higher than the clutch-in rotation speed and from 1.0 time to 1.6 times of the clutch-in rotation speed.

5 . The easy engine starting system according to claim 4 , wherein the throttle opening degree has a target corresponding to a rotation speed equal to or higher than the clutch-in rotation speed and from 1.0 time to 1.3 times of the clutch-in rotation speed.

6 . The easy engine starting system according to claim 1 , further comprising a detection unit configured to detect the rotation speed of the engine,
wherein the control device is configured to control ignition timing in the first start-time PI control step using feedback control based on a deviation between a target rotation speed and the detected rotation speed.

7 . The easy engine starting system according to claim 6 , wherein the feedback control is started when at least one of the detected rotation speed, the rotation speed, or a time satisfies a predetermined condition after the engine is started.

8 . The easy engine starting system according to claim 7 , wherein the feedback control has:
first feedback control of executing feedback control such that the rotation speed falls within a first rotation speed range; and second feedback control of executing, after the first feedback control, feedback control such that the rotation speed falls within a second rotation speed range wider than the first rotation speed range.

9 . The easy engine starting system according to claim 8 , wherein the engine includes a recoil having a rope to be pulled by hand when the engine is to be started.

10 . The easy engine starting system according to claim 9 , wherein the engine is a two-stroke engine mounted to a handheld blade working machine.

11 . The easy engine starting system according to claim 1 , wherein the control device is configured to calculate the number of engine rotations.

12 . The easy engine starting system according to claim 1 , wherein the control device is configured to transition from the start mode to the first start-time PI control step after a number of engine rotations at a speed exceeding a transition determination rotation speed is greater than a predetermined number, and
wherein the transition determination rotation speed is a rotation speed lower than the clutch-in rotation speed.

13 . The easy engine starting system according to claim 1 , wherein the control device is configured to transition from the start mode to the first start-time PI control step within a predetermined number of rotations from a user starting the engine.

14 . The easy engine starting system according to claim 1 , further comprising a temperature sensor coupled to the engine and configured to sense the temperature of the engine,
wherein the control device is configured to receive a signal from the temperature sensor, digitize the signal, and transition from the first start-time PI control step to the second start-time PI control step based on a predetermined increase in temperature calculated from the digitized signal.

Assignees

• Yamabiko Corp
• Oppama Ind Co Ltd

Inventors

• Tanabe Akira
• Saito Tamotsu
• Imai Ryosuke
• KAJIYAMA Ryosuke

Classifications

• F16D43/06

  with centrifugal masses actuating axially a movable pressure ring or the like · CPC title

• F02M9/06

  with means for varying cross-sectional area of fuel spray nozzle dependent on throttle position (installations, operated automatically by a pneumatically adjustable piston-like element, for influencing fuel/air ratio F02M7/17) · CPC title

• F02D2200/021

  Engine temperature · CPC title

• F02B63/02

  for hand-held tools · CPC title

• F02D2200/101

  Engine speed · CPC title