Engine Torque Diagnosis With Operating-State Adaptive Filtering
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Solution Overview
Problem
Existing engine diagnosis methods, such as those described in JP2018-105305A, face accuracy issues in diagnosing engine torque due to varying response characteristics based on engine operating states, leading to inaccuracies in torque state determination.
Innovation Solution
The method involves calculating a corrected command torque by adjusting a correction amount based on the engine's response characteristic, using variable filter parameters like dead time and first-order lag coefficients specific to the engine's operating state, and comparing this with an estimated torque to diagnose the engine's state accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a uniform filter is applied to the command torque regardless of engine operating state, then the calculation is simple, but the diagnostic accuracy deteriorates because the response characteristic varies with operating state
Solution Approach 1:
The filter parameter K is changed from a fixed value to a variable value that dynamically adjusts according to engine operating state. Specifically, K is set to different values based on whether the engine is in a torque increase state, torque decrease state, or steady state, allowing the filtering process to adapt to varying response characteristics and maintain diagnostic accuracy across different operating conditions
Solution Approach 2:
The filtering parameter K is modified based on the engine's operational state. When torque increases, a first filter parameter is used; when torque decreases, a second filter parameter is used; when torque is steady, a third filter parameter is used. This parameter change enables the system to account for different response characteristics in different operating regimes, resolving the contradiction between simple calculation and accurate diagnosis
2Measurement precision
If the correction amount is adjusted according to engine operating state, then the diagnostic accuracy is improved, but the calculation complexity increases
Solution Approach 1:
The correction amount is adjusted by changing the filter parameter K based on engine operating state. The system determines whether the engine is in a torque increase state, torque decrease state, or steady state, and selects the appropriate filter parameter accordingly. This approach improves diagnostic accuracy by adapting to different operating conditions while keeping the calculation method relatively simple through systematic parameter selection
Data Source
AI summary
An engine diagnosis method includes: a step of calculating a corrected command torque Ttrg2 by correcting a command torque Ttrg of an engine 1 with a correction amount according to a response characteristic of an engine torque T actually output with respect to the command torque Ttrg; and a step of diagnosing a state of the engine torque T by comparing a diagnostic torque Tdia defined based on the corrected command torque Ttrg2 and an estimated torque Tact. Particularly, in this engine diagnosis method, the correction amount is adjusted with reference to an operating state of the engine 1.