Camshaft Phase Angle Adjustment via Triple-Shaft Gear Mechanism
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Solution Overview
Problem
During the startup process of an internal combustion engine, there is a lack of measurement values for the phase position of the camshaft, which hinders efficient adjustment and results in higher pollutant emissions and fuel consumption.
Innovation Solution
A method that involves setting initial rotational and position measurement signals, detecting changes in crankshaft and adjustment shaft sensor signals, determining the phase angle signal using these measurements and gear parameters, and controlling the electric motor to adjust the phase angle to a desired value, allowing for early phase angle correction and improved engine efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the engine is started without phase position measurement values, then the startup process can begin immediately, but pollutant emissions increase and fuel consumption rises
Solution Approach 1:
The system performs preliminary actions by detecting the crankshaft's initial position using a crankshaft position sensor before startup, and pre-calculating the required camshaft phase angle. This allows the phase adjustment mechanism to be pre-positioned, enabling immediate efficient operation upon startup without the need for runtime measurement and adjustment, thus reducing emissions while maintaining fast startup.
2Measurement precision
If the phase angle is adjusted during startup without initial measurement values, then measurement information is lacking, but the adjustment can still be made using indirect calculation methods
Solution Approach 1:
The system uses the crankshaft position sensor as an intermediary to indirectly determine the camshaft phase position. By measuring the crankshaft's rotational position and using the known gear ratio relationship between the crankshaft and camshaft, the system can calculate the camshaft's phase angle without requiring direct sensors on the camshaft, thus recovering the lost measurement information through indirect measurement and calculation.
3Measurement precision
If a crankshaft position sensor is added to enable phase angle determination, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The crankshaft position sensor serves multiple functions: it detects the crankshaft's rotational position for phase angle calculation, provides timing information for the injection and ignition systems, and enables monitoring of engine speed and operational state. By making this single sensor multi-functional, the system achieves improved measurement capability without proportionally increasing device complexity, as the sensor's data is reused across multiple control functions.
Data Source
AI summary
A method for adjusting the rotational angle position of the camshaft (3) of a reciprocating piston internal combustion engine relative to the crankshaft (5) is provided. The crankshaft (5) is drivingly connected to the camshaft (3) via an adjusting drive (1), which is embodied as a triple-shaft gear mechanism, having a crankshaft-fixed drive shaft, a camshaft-fixed output shaft, and an adjustment shaft drivingly connected to an electric motor (4). A stop element is connected to the drive shaft and a counter-stop element is connected to the camshaft (3). The crankshaft rotational angle measuring signal and a position signal for the rotational angle of the adjusting shaft are detected during the starting step of the internal combustion engine. A phase angle signal for the position of the rotational angle of the camshaft (3), based on the initial position, in relation to the camshaft (3) is determined with the aid of the angle measuring signal, the position measuring signal and a gear variable of the triple shaft gear. After immobilization of the crankshaft (5) and the camshaft (3) in a reference position in relation to each other and after detection of the reference position, the phase angle in relation to the reference position is measured and is controlled to a target value signal.