Crankcase Pressure Sensor Ambient Pressure Determination
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Solution Overview
Problem
Existing hand-held internal combustion engine systems in hand-held working devices face challenges in determining ambient pressure without additional sensors, which is crucial for accurate fuel supply control due to varying altitudes affecting ambient pressure levels.
Innovation Solution
Utilizing the existing crankcase pressure sensor to determine ambient pressure by measuring pressure values during specific crankshaft angle ranges, eliminating the need for additional sensors and enabling energy supply exclusively through the crankshaft movement, thus allowing for direct measurement of ambient pressure without pre-start energy storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an additional pressure sensor is installed to determine ambient pressure, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The crankcase pressure sensor, originally designed solely for monitoring crankcase pressure during engine operation, is repurposed to also determine ambient pressure by measuring crankcase pressure during the starting process before combustion occurs. This multi-functional use eliminates the need for a separate ambient pressure sensor, reducing device complexity while maintaining measurement capability
Solution Approach 2:
The existing crankcase pressure sensor serves itself by providing dual functionality - it continues its primary role of monitoring crankcase pressure during operation while simultaneously determining ambient pressure during the starting phase. The sensor's existing infrastructure is utilized to its full potential without requiring additional measurement components
2Use of energy by moving object
If a separate energy store (battery/accumulator) is added to supply power to the pressure sensor before engine start, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The crankshaft serves itself by generating electrical energy through its rotation during the starting process. The manually operated starter mechanism converts mechanical energy from crankshaft rotation into electrical energy that directly powers the pressure sensor and evaluation device, eliminating the need for a separate battery or accumulator
Solution Approach 2:
The crankshaft acts as an intermediary energy converter, transforming the mechanical energy from manual starting operations into electrical energy that temporarily powers the electronic components during the critical pre-combustion measurement phase. This intermediary function replaces the need for dedicated energy storage devices
3Use of energy by moving object
If pressure measurement is performed after combustion begins, then energy availability is improved, but measurement precision deteriorates due to pressure changes from combustion
Solution Approach 1:
The ambient pressure measurement is performed preliminarily during the starting process before combustion occurs. By capturing the pressure data in advance, when the crankcase pressure still reflects only ambient conditions and not yet influenced by combustion, the system ensures measurement precision while utilizing the energy available during the starting phase
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
Enables accurate determination of ambient pressure for fuel control, reduces the need for additional sensors, and provides feedback on air filter contamination, ensuring optimal engine performance by compensating for altitude and temperature influences.
Implementation Method 1
at least one pressure value is measured with the crankshaft in a first crankshaft angle range, in which the crankcase is connected to the environment via the overflow channels, the combustion chamber and the outlet opening
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
The method involves measuring the crankcase pressure using a crankcase pressure sensor (21) of the combustion chamber (3), and evaluating the measured values of the crankcase pressure sensor using an evaluation device (23). The ambient pressure is determined using the crankcase pressure during the starting process of the combustion engine (1) while rotating the crankshaft (7) before the initial combustion. The crankcase pressure sensor is supplied with energy during the measurement through the movement of the crankshaft.