Crank Angle Determination Using Cylinder Pressure Medium
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Solution Overview
Problem
Existing methods for determining the crank angle of multicylinder internal combustion engines, such as using incremental encoders or absolute rotary encoders, are either time-consuming, energy-intensive, or prone to failure due to fragility, especially when the engine is at rest, and do not efficiently minimize starting air consumption.
Innovation Solution
A method that introduces a predetermined amount of pressure medium into at least two engine cylinders, measures the pressure, and calculates the crank angle using pressure sensors and control units, eliminating the need for absolute rotary encoders and reducing energy consumption by determining the crank angle before engine startup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an absolute rotary encoder is used to determine the crank angle when the engine is at rest, then the measurement precision is improved, but the reliability deteriorates due to fragility and limited lifetime
Solution Approach 1:
The patent replaces the mechanical absolute rotary encoder with a pneumatic measurement system. Pressure medium is introduced into the cylinder and the resulting pressure changes are measured to determine the crank angle position and engine speed, eliminating the fragile mechanical encoder while maintaining measurement capability
Solution Approach 2:
The invention uses pneumatic principles by introducing pressure medium into the cylinder and measuring pressure changes. The pressure medium interacts with the piston-crank mechanism to produce measurable pressure signals that indicate crank angle position without requiring mechanical sensors
2Measurement precision
If the engine is rotated to pass a reference mark past the crank angle sensor, then the measurement precision is improved, but the use of energy and time increase significantly
Solution Approach 1:
The patent performs preliminary action by determining the crank angle position while the engine is still at rest, before any rotation occurs. Pressure medium is introduced and pressure measurements are taken in the stationary state, eliminating the need for subsequent rotation to establish reference
Solution Approach 2:
The mechanical rotation method is replaced with a pneumatic measurement method that works in the stationary state. The pressure medium and pressure sensor system can determine crank angle without requiring engine movement, thus saving energy and time
3Measurement precision
If the engine is rotated to pass a reference mark past the crank angle sensor, then the measurement precision is improved, but the loss of time increases due to the time-consuming process
Solution Approach 1:
The crank angle determination is performed as a preliminary action while the engine is at rest, before the starting sequence begins. This eliminates the time required for rotation and reference mark detection, allowing immediate identification of the correct cylinder for starting air injection
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 and efficient determination of the crank angle at rest without fragile encoders, minimizing starting air consumption and energy use, and does not require additional flow regulation devices or separate pressure sources.
Implementation Method 1
measuring pressure in the cylinders into which the pressure medium has been introduced
Data Source
Figure 1
AI summary
A method for determining the crank angle of an internal combustion engine (1) when the engine (1) is at rest, the method comprising the steps of introducing a predetermined amount of pressure medium into at least two of the cylinders (4) of the engine (1), measuring pressure in the cylinders (4) into which the pressure medium has been introduced, and calculating the crank angle of the engine (1) on the basis of the pressure measurements. The invention also concerns an arrangement for determining the crank angle of an internal combustion engine (1).