Cam Phaser Control Algorithm for Intermediate Locking Pin
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Solution Overview
Problem
Existing ILP camshaft phasers require improved control and diagnostic methods to ensure reliable operation across various engine conditions, as the addition of an intermediate locking pin and separate control valve introduces complex control requirements for engine management systems.
Innovation Solution
An improved control and diagnostic algorithm coordinates the operation of the oil control valve and intermediate locking pin valve, using pulse-width modulation and feedback loops to manage the rotational position of the rotor and lock pin, with diagnostic functions to detect and report malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an intermediate locking pin and separate ILP control valve are added to enable intermediate position locking, then the rotor can be locked at intermediate positions improving cam phaser control precision, but the device complexity and control algorithm complexity increase significantly
Solution Approach 1:
The locking pin is nested within the rotor structure, sliding in a bore through the rotor vane. The ILP control valve integrates with the existing OCV structure, sharing the same housing and oil supply connections. This nesting approach adds intermediate locking capability while minimizing additional external components and complexity.
Solution Approach 2:
The locking pin acts as an intermediary element between the rotor and stator, providing mechanical locking at intermediate positions. The ILP control valve serves as an intermediary control mechanism, receiving commands from the ECU and regulating oil flow to the locking pin independently of the main OCV, enabling precise intermediate position control.
2Adaptability or versatility
If an ILP control valve is added to control oil flow to the locking pin, then intermediate position locking capability is achieved, but the control algorithm complexity and diagnostic requirements increase
Solution Approach 1:
The control system is segmented into two independent control loops: the OCV controls the main cam phaser rotation, while the ILP control valve independently controls the locking pin engagement. This segmentation allows each valve to be controlled separately by the ECU, enabling versatile cam phaser operation modes including continuous rotation and intermediate position locking without requiring complex coordinated control algorithms.
Solution Approach 2:
The system dynamically switches between different operational modes: continuous rotation mode where the locking pin is disengaged, and intermediate locking mode where the locking pin engages at predetermined positions. The ECU dynamically controls the ILP valve duty cycle to achieve timely engagement and disengagement, adapting to different engine operating conditions and improving overall system versatility.
3Length of moving object
If the locking pin is made smaller to reduce interference with rotor rotation, then rotor rotational authority is improved, but the locking pin strength and reliability may be compromised
Solution Approach 1:
The locking pin exhibits local quality variations: it has a reduced diameter portion that fits within the rotor vane bore, minimizing interference with rotor rotation and allowing greater rotational authority. The pin also has enlarged head portions at each end that engage with the rotor and stator, providing sufficient locking strength and mechanical advantage despite the reduced shaft diameter. This local quality differentiation optimizes both rotational freedom and locking reliability.
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
Enhances the reliability and operation of ILP camshaft phasers by ensuring precise control and timely engagement/disengagement of the lock pin, reducing position errors and improving engine performance and diagnostic capabilities.
Implementation Method 1
The position of the rotor is governed by application of pressurized oil to one side or the other of the rotor vanes via an oil control valve (OCV)
Implementation Method 2
a separate oil ILP control valve is used to control oil flow to the ILP locking pin with a separate command from the ECU
Data Source
AI summary
An improved control and diagnostic algorithm for coordinating the operation and checking reliability of oil control valves for a vane-type camshaft phaser in an internal combustion engine. A first oil control valve governs the rotational position of the phaser rotor within the stator, and a second oil control valve controls the locking and unlocking of a locking pin operable between the rotor and the stator. The algorithm determines when a change is needed in the position of the locking pin, commands the rotor to a predetermined angular position to permit the position change to be carried out, determines whether the commanded change was carried out successfully, and reports instances wherein the commanded locking pin position change was unsuccessful.