Air-Cooled Engine Temperature Control via Fuel Enrichment
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Solution Overview
Problem
Portable handheld work apparatus, such as chain saws, face issues with inadequate cooling due to obstructed air intake, leading to undesirable engine temperatures and reduced service life.
Innovation Solution
Incorporating a temperature sensor to monitor engine components, with a power control system that adjusts operating parameters, such as fuel mixture enrichment, ignition suppression, and rpm changes, to maintain optimal temperatures, and providing acoustic and optical alerts for excessive temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the cooling air blower is flanged directly on the crankshaft to ensure cooling, then the cooling air flow is proportional to engine speed, but the cooling efficiency deteriorates when the air intake is obstructed by leaves or debris
Solution Approach 1:
The patent employs a temperature sensor that continuously monitors engine temperature and feeds this information back to the control unit. When obstruction is detected through temperature rise, the control unit responds by enriching the fuel mixture and adjusting ignition timing, creating a closed-loop feedback system that maintains cooling effectiveness despite air intake blockage
Solution Approach 2:
The control unit dynamically changes engine operating parameters based on temperature feedback. When cooling efficiency drops due to obstruction, the system enriches the fuel-air mixture ratio and adjusts ignition timing to reduce combustion temperature and power output, thereby maintaining acceptable engine temperatures under unfavorable conditions
2Productivity
If the power output is increased to improve productivity, then the engine generates more power, but the temperature increases leading to reduced service life
Solution Approach 1:
The patent implements dynamic adjustment of engine operating parameters based on real-time temperature monitoring. The control unit continuously adapts the fuel injection amount and ignition timing according to temperature conditions, allowing the engine to operate at high power when cool and automatically reduce power when temperature rises, thus extending service life while maximizing productivity when conditions permit
Solution Approach 2:
The temperature sensor provides continuous feedback to the control unit, which adjusts power output parameters accordingly. When temperature approaches critical levels, the system reduces power output through fuel mixture enrichment and ignition timing adjustment, preventing overheating and extending engine service life while maintaining high productivity during normal operating conditions
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
Ensures sufficient cooling of the air-cooled combustion engine even under unfavorable conditions, preventing overheating and extending engine service life by dynamically adjusting power output and cooling airflow.
Implementation Method 1
a temperature sensor configured to directly or indirectly measure the temperature of at least one component of the combustion engine and outputting a temperature signal in dependence upon the temperature
Implementation Method 2
a cooling air blower for generating a cooling air flow to cool the cylinder
Implementation Method 3
a fuel metering device for supplying fuel
Implementation Method 4
a spark plug projecting into the combustion chamber and being controlled by the ignition control to trigger an ignition spark in dependence on the rpm and the angular position of the crankshaft to ignite the air/fuel mixture
Implementation Method 5
the combustion chamber being configured to be supplied with an air/fuel mixture
Implementation Method 6
the piston and a cylinder having a combustion chamber delimited by the piston
Data Source
AI summary
A portable, handheld work apparatus such as a chain saw has a handle (5, 7) to guide the work apparatus (1) and has an air-cooled, mixture-lubricated combustion engine (10) arranged in a casing as a drive for a work tool (3). The cylinder (11) has a combustion chamber (13) formed therein to which an air/fuel mixture is supplied. The air/fuel mixture is ignited by a spark plug (23) which projects into the combustion chamber (13). An ignition control (30) triggers a spark in dependence on the angular position of the crankshaft (15). A temperature sensor (35, 45, 55) is provided to control the cylinder temperature. The temperature signal of the temperature sensor (35, 45, 55) is connected to a power control (40). When a predetermined temperature is exceeded, the power control (40) changes the operating parameters of the combustion engine (10) in such a manner that the power of the combustion engine (10) is changed.