Indirect Integration for Accurate IMEP with Low-Resolution Encoder
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Solution Overview
Problem
Existing methods for calculating indicated mean effective pressure (IMEP) in internal combustion engines require high-resolution crankshaft position and frequent cylinder pressure data, leading to increased costs due to the need for advanced encoders, memory, and computing power.
Innovation Solution
An indirect integration method using sparse input data, which allows for lower-resolution crankshaft position and cylinder pressure data, enabling accurate IMEP calculations through the use of equations such as Equation (7) and the cubic spline integration method, reducing the computational and storage requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-resolution crankshaft position encoder and frequent cylinder pressure measurement are used, then IMEP calculation accuracy is improved, but system cost and complexity increase
Solution Approach 1:
The patent introduces an intermediary mathematical model (indirect integration method using cubic spline integration) that transforms the relationship between crankshaft position data and IMEP calculation. This intermediary approach allows accurate IMEP computation without requiring high-resolution encoder data, as the mathematical model interpolates and integrates the pressure data indirectly through the relationship d(PV^n) = V^n dP + nV^{n-1}PdV, where the integration process mediates between sparse position data and accurate IMEP results.
Solution Approach 2:
The patent changes the parameter of crankshaft position resolution from high-resolution to low-resolution (coarser sampling increments of 3 or 6 degrees). By modifying this input parameter and compensating through the indirect integration mathematical approach, the system achieves accurate IMEP calculations without requiring high-resolution encoder data, thus reducing device complexity and cost.
2Measurement precision
If high-resolution crankshaft position data is used, then IMEP calculation accuracy is improved, but data storage requirements increase
Solution Approach 1:
The indirect integration method acts as an intermediary that processes sparse pressure data through mathematical integration rather than requiring storage of high-resolution data points. The method uses the relationship IMEP = (1/V_cyl) ∫ P dV and transforms it into an indirect integration form that can be computed from coarser sampling data, eliminating the need to store large volumes of high-resolution data.
Solution Approach 2:
The patent uses partial action by sampling cylinder pressure at fewer, coarser intervals (3 or 6 degree crank rotation increments) rather than continuously at high resolution. The indirect integration method then processes these partial data points to produce the complete IMEP calculation, reducing the quantity of data that needs to be stored while maintaining accuracy.
3Measurement precision
If frequent cylinder pressure measurement is used, then IMEP calculation accuracy is improved, but computing power requirements increase
Solution Approach 1:
The indirect integration method serves as a computational intermediary that reduces the processing burden. Instead of directly integrating frequent high-resolution data points, the method uses the transformed equation that can be computed from sparse data: IMEP = (P_{k+Δ} - P_k) / (V_cyl/n) * [G_k - H_k], where G_k and H_k are pre-computed volume-related terms. This intermediary approach significantly reduces real-time computing power requirements.
Solution Approach 2:
The patent applies preliminary action by pre-computing the volume-related terms G_k and H_k offline before real-time operation. These pre-computed values are stored and reused during IMEP calculations, eliminating the need for repeated complex volume calculations during real-time processing. This preliminary preparation reduces the computing power needed during actual engine operation.
Data Source
AI summary
A method for computing indicated mean effective pressure (IMEP) in an internal combustion engine using sparse input data. The method uses an indirect integration approach, and requires significantly lower resolution crankshaft position and cylinder pressure input data than existing IMEP computation methods, while providing calculated IMEP output results which are very accurate in comparison to values computed by existing methods. By using sparse input data, the indirect integration method offers cost reduction opportunities for a manufacturer of vehicles, engines, and/or electronic control units, through the use of lower cost sensors and the consumption of less computing resources for data processing and storage.