Variable Compression Engine Diagnosis Using Crankshaft Irregularity
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Solution Overview
Problem
Existing reciprocating piston engines with variable compression ratios face challenges in accurately determining and adjusting compression ratios, which affects rotational non-uniformity and can lead to inefficient operation and potential faults in adjustment mechanisms.
Innovation Solution
A method and system that adjust the compression ratio of reciprocating piston engines by measuring rotational non-uniformity parameters at different crank angles, using existing sensors to determine compression ratio parameters, and filtering data to reduce non-cylinder-induced components, allowing for precise adjustment and diagnosis of compression ratio changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If compression ratio is adjusted in reciprocating piston engines, then engine functionality is improved and adapted to different load ranges, but determination and control of compression ratio becomes more complex
Solution Approach 1:
The patent replaces complex mechanical measurement systems with a diagnostic method based on analyzing rotational non-uniformity of the crankshaft. By using existing sensors to detect rotational variations and correlating them with compression ratio changes, the system avoids complex mechanical measurement apparatus while achieving accurate compression ratio determination.
Solution Approach 2:
The diagnostic system utilizes the engine's own operational characteristics - specifically the rotational non-uniformity that naturally occurs during compression strokes - to determine compression ratio. The engine essentially measures itself through its own dynamic behavior, eliminating the need for external measurement devices.
2Difficulty of detecting and measuring
If compression ratio changes are monitored using rotational non-uniformity measurement, then compression ratio determination is simplified, but measurement precision may be affected by non-cylinder-induced components
Solution Approach 1:
The patent extracts and isolates the cylinder-induced rotational non-uniformity components from the total rotational non-uniformity signal. By filtering out non-cylinder-induced components through comparative analysis and signal processing, the system obtains a purified measurement that accurately reflects compression ratio changes.
Solution Approach 2:
The system uses feedback from rotational non-uniformity measurements to continuously monitor and determine compression ratio. By comparing measured rotational variations with expected patterns and adjusting the determination accordingly, the system maintains measurement precision while using a simplified approach.
3Device complexity
If existing sensors are used to determine compression ratio parameters, then device complexity is reduced, but measurement precision and reliability may be compromised
Solution Approach 1:
The patent makes existing sensors serve multiple functions - primarily for crankshaft position and speed detection, and secondarily for compression ratio determination. By extracting additional diagnostic information from the same sensor signals already present in the engine control system, the patent avoids adding dedicated measurement devices while achieving accurate compression ratio monitoring.
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
This approach enables accurate determination and adjustment of compression ratios, improves engine operation by reducing disturbances, and allows for the detection of faulty adjustment mechanisms, thereby enhancing engine performance and reliability.
Implementation Method 1
a compression ratio, in particular a change in a compression ratio, influences a rotational non-uniformity of the reciprocating piston engine in a characteristic manner
Implementation Method 2
the detected crank angle and/or the at least one time derivation are filtered, in particular numerically, and the first rotational non-uniformity parameter value is determined on the basis of the filtered crank angle and/or the at least one filtered time derivation
Data Source
Figure 1~3
AI summary
The invention relates to a method for diagnosing and/or controlling a reciprocating engine having a variable compression ratio, wherein the method comprises the working steps: determining (S30) a first value (U1,1; U1,2; Δ1) of a rotational irregularity parameter of a crankshaft (1) of the reciprocating engine; and determining (S60) a value of a compression ratio parameter for the reciprocating engine based on said first rotational irregularity parameter value.