Cylinder Detection in Four-Stroke Engines via Dual-Disc Sensor
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Solution Overview
Problem
Current cylinder detection systems in four-stroke internal combustion engines face challenges in accurately identifying which piston is about to reach its ignition top dead centre position, especially when the crankshaft sensor fails, leading to inefficiencies in fuel injection control.
Innovation Solution
The system employs a dual-disc arrangement with a first disc connected to the crankshaft and a second disc connected to the camshaft, each with specific marks detectable by sensors, allowing the combustion engine control unit to determine the relative rotational positions and identify the correct cylinder for fuel injection based on unique phase differences between signals from the sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single crankshaft sensor with one reference mark is used, then the structure is simple, but cylinder identification becomes ambiguous when count is lost or during engine start
Solution Approach 1:
The patent combines crankshaft position detection (first disc with reference mark) and camshaft position detection (second disc with multiple marks) into a single integrated sensor system. The sensor reads both discs simultaneously, merging two detection functions into one device, which resolves the contradiction by maintaining structural simplicity while achieving reliable cylinder identification through the combined information from both discs
Solution Approach 2:
The single sensor assembly serves multiple functions: detecting the crankshaft reference mark for general position reference, detecting camshaft marks for cylinder identification, and providing redundant information for reliable operation during engine start or count loss. This multi-functionality allows the system to maintain reliability without increasing device complexity
2Reliability
If separate crankshaft and camshaft sensors are used, then cylinder detection reliability improves, but device complexity increases
Solution Approach 1:
The patent merges separate crankshaft and camshaft sensor assemblies into a single integrated sensor that reads both the first disc (crankshaft reference) and second disc (camshaft marks). This consolidation maintains the reliability benefits of dual-d disc detection while reducing device complexity by eliminating separate sensor housings, mounting structures, and signal processing paths
3Ease of operation
If only one reference mark on the crankshaft is used, then the system is simple to operate, but fuel injection control becomes inefficient when the sensor fails or count is lost
Solution Approach 1:
The system preliminarily establishes multiple reference points (first reference mark on crankshaft, second and third reference marks on camshaft) during normal operation. These pre-established references enable the control system to quickly re-synchronize and resume efficient fuel injection control after sensor failures or count loss without requiring complex diagnostic procedures or manual intervention
Solution Approach 2:
The patent implements beforehand cushioning by providing redundant reference marks and dual-d disc detection capability. This redundancy acts as a protective buffer against sensor failures or count loss, ensuring that fuel injection control efficiency is maintained even when unexpected failures occur, as the system can switch to alternative reference points without interruption
Data Source
Figure 1~2
Figure 3~4b
Figure 5a~5b
AI summary
Herein an arrangement (4) for cylinder detection in a four-stroke internal combustion engine (2) is disclosed. The arrangement (4) comprises a first disc (16) connected to a crankshaft (6), the first disc (16) comprising a first mark (M11 – M13) within each an interspace angle (α), and a second disc (18) connected to a camshaft (12) and comprising one second mark (M21 – M26) per number of cylinders. The first mark (M11 – M13) is arranged on a first disc (16), or the first marks (M11 – M13) are arranged in relation to each other on the first disc (16), and the second marks (M21 – M26) are arranged in relation to each other on the second disc (18) such that for each interspace angle (α) the relevant first mark (M11 – M13) is detectable by a first sensor (20) and the relevant second mark (M21 – M26) is detectable by a second sensor (22) at different relative rotational positions between the first disc (16) and the second disc (18).