Camshaft Positioning via Rotational Speed Gradient Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing methods for synchronizing the camshaft and crankshaft in internal combustion engines lead to inaccuracies during engine start-up, particularly during cold starts, resulting in prolonged starting times and increased emissions, as the phase angle adjustments are not precise, causing the crankshaft to potentially reverse direction, necessitating re-synchronization and affecting fuel efficiency and emissions.
Innovation Solution
A method utilizing an electric camshaft adjustment device with a control device that monitors the direction of rotation and calculates a rotational speed gradient to correct the pulse duty factor, ensuring the camshaft is positioned optimally before engine start, thereby eliminating the need for phase adjustment during start-up and reducing starting time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the phase angle between camshaft and crankshaft is adjusted using conventional encoder wheel and Hall sensor methods, then the synchronization can be achieved, but the starting time is prolonged and emissions increase due to inaccurate positioning and potential crankshaft reversal
Solution Approach 1:
The patent replaces the mechanical encoder wheel with teeth and Hall sensor detection system with a magnetic field-based sensor system. The sensor detects the position of a magnet attached to the camshaft, eliminating the need for mechanical teeth structures. This substitution enables more precise and rapid position detection, reducing starting time while improving measurement accuracy.
Solution Approach 2:
The patent implements preliminary camshaft positioning before the engine start command is executed. The control device calculates the required camshaft position based on the desired crankshaft position and phase relationship, and activates the adjustment device in advance to position the camshaft correctly before ignition begins. This preliminary action prevents starting delays and reduces emissions by ensuring optimal valve timing from the moment of engine start.
2Reliability
If the camshaft position is adjusted during the starting process, then synchronization can be achieved, but the starting process becomes longer and fuel consumption increases
Solution Approach 1:
The control device performs preliminary calculation of the required camshaft adjustment before the engine start command. It determines the target camshaft position based on the current crankshaft position and the desired phase relationship, then executes the adjustment in advance. This ensures the camshaft is already in the correct position when the engine starts, eliminating delays and reducing fuel consumption during the starting process.
Solution Approach 2:
The patent implements a feedback mechanism where the sensor continuously monitors the actual camshaft position and feeds this information back to the control device. The control device compares the actual position with the target position and adjusts the adjustment device accordingly. This closed-loop feedback ensures reliable synchronization while minimizing adjustment time and fuel consumption by making precise, targeted corrections rather than prolonged adjustments.
3Adaptability or versatility
If conventional encoder wheels with multiple teeth are used for synchronization, then the phase relationship can be established, but faulty camshaft positions occur during reversal of rotation direction
Solution Approach 1:
The patent replaces the mechanical encoder wheel with teeth that requires complex detection logic for rotation direction changes with a magnetic field-based sensor system. The magnet attached to the camshaft creates a magnetic field that the sensor detects regardless of rotation direction. This eliminates the faulty position detection that occurs with conventional encoder wheels during reversal, providing reliable and accurate camshaft position information throughout the entire operating range including shutdown and restart conditions.
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 significantly shortens the starting process, improves fuel efficiency, reduces emissions, and enhances engine performance by ensuring precise camshaft positioning, even during cold starts, by compensating for rotation reversals and optimizing compression and cylinder filling.
Implementation Method 1
On this encoder wheel there are teeth which are sensed e.g. by a Hall sensor when the camshaft rotates.
Implementation Method 2
An electric-motor-operated camshaft adjustment device is composed of an adjustment mechanism which is connected in a rotationally fixed fashion to the camshaft and an electric-motor-operated adjustment drive
Data Source
AI summary
A method according to the invention for controlling an internal combustion engine having a camshaft whose phase with respect to a crankshaft can be adjusted by means of an electric adjustment device, and a control device comprises the steps S1 to S3, wherein in step S1 a stop request is output from the control device to the electric adjustment device. Subsequently, in step S2 a manipulated variable in the form of a pulse duty factor is output from the electric adjustment device, wherein the pulse duty factor counteracts a camshaft torque. In step S3, the direction of rotation of the camshaft is monitored, wherein in step S4, when a reversal of the direction of rotation of the camshaft is detected, an intensity level of this reversal of the direction of rotation is calculated by determining a rotational speed gradient. Furthermore, in a step S5 the pulse duty factor is corrected as a function of the rotational speed gradient in such a way that the influence of the reversal of the direction of rotation on the position of the camshaft is compensated.