Engine Controller Rotational Speed Limitation Muffler Heat
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Solution Overview
Problem
Engine-driven working machines, such as chain saws, experience increased muffler temperature and catalyst durability degradation due to prolonged fast idling and rotational speed limitation modes, making it difficult for operators to distinguish between not-in-use and normal idling states, leading to unnecessary heat generation and catalyst degradation.
Innovation Solution
Implementing a controller that initiates a rotational speed limitation mode upon engine start, performing misfiring cycles to prevent excessive speed, and subsequently forcing the engine to stop after a predetermined period, regardless of operator awareness, to prevent muffler temperature increase and catalyst degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine operates in fast idling state with throttle valve half-opened to stabilize starting and running operations, then the engine starting and running stability is improved, but the muffler temperature increases and catalyst durability degrades due to prolonged operation
Solution Approach 1:
The controller monitors engine operating conditions and automatically adjusts throttle valve position based on feedback signals. When the engine is in fast idling state, the controller detects this condition and automatically moves the throttle valve to fully-opened position after a predetermined time, preventing prolonged high temperature operation of the catalyst while maintaining starting stability
Solution Approach 2:
The throttle valve position is dynamically adjusted based on engine operating conditions. The system transitions from half-opened position during starting to fully-opened position during operation, allowing the engine to adapt to different operational phases and avoid sustained high temperature catalyst exposure
2Reliability
If the controller operates in rotational speed limitation mode to prevent excessive engine speed after starting, then engine speed control is improved, but the operator cannot distinguish between not-in-use and normal idling states leading to unnecessary heat generation
Solution Approach 1:
The controller implements periodic misfiring cycles during rotational speed limitation mode to maintain engine speed control while reducing heat generation. This periodic action allows the engine to operate in a controlled manner without continuous high temperature exposure, and the system automatically transitions to fast idling after predetermined time to inform operator of machine readiness
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents muffler temperature rise and catalyst durability degradation by ensuring the engine stops after a set period in the rotational speed limitation mode, even if the operator is unaware the machine is not in use, thus extending catalyst lifespan and maintaining muffler performance.
Implementation Method 1
A catalyst for purifying exhaust gas of an internal combustion engine is contained in the muffler
Implementation Method 2
the controller prevents the rotational speed of the engine from becoming higher than the limitation rotational speed by performing a misfiring cycle which makes an ignition device of the engine inoperative
Data Source
Figure 1
Figure 2
Figure 3(a)~3(c)
AI summary
An engine-driven working machine according to the present invention has a controller and a muffler. The controller is operated from starting of the engine in a rotational speed limitation mode in which the engine is prevented from rotating at a rotational speed that is higher than the predetermined limitation rotational speed. The controller forces to stop the engine, after a predetermined period has passed, during which the engine operates in the rotational speed limitation mode.