Camshaft Phaser Compound Planetary Gear Actuator
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Solution Overview
Problem
Existing camshaft phasers face issues with phase relationship drift due to leakage, requiring continuous actuation to correct, and often rely on mechanical or electrical systems with limitations such as slip rings, which are undesirable.
Innovation Solution
A camshaft phaser with a compound planetary gear set and an adjusting actuator that can switch between idling and adjusting states, allowing for precise rotational control of the valve spool to maintain or adjust the phase relationship between the crankshaft and camshaft, eliminating the need for continuous motor operation and avoiding slip rings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional phasing oil control valve is used to correct phase relationship drift, then the phase relationship can be corrected, but the system requires continuous actuation and cannot self-correct
Solution Approach 1:
The valve spool is designed to automatically self-correct phase relationship drift without requiring continuous actuation by the adjusting actuator. The spring-loaded valve spool naturally responds to pressure differential changes caused by leakage, automatically adjusting oil flow to maintain the desired phase relationship, thereby eliminating the need for continuous motor operation and reducing system complexity
Solution Approach 2:
The system incorporates inherent feedback through the spring-loaded valve spool mechanism that automatically detects and responds to phase relationship deviations caused by leakage. The valve spool position is continuously adjusted based on pressure differential feedback from the advance and retard chambers, enabling automatic correction without external control signals
2Ease of operation
If an electric motor with slip rings is used to rotate the valve spool, then precise rotational control is achieved, but the system becomes more complex and less reliable due to slip rings
Solution Approach 1:
The patent replaces the electric motor with slip rings with a simplified mechanical rotational actuator system. The adjusting actuator (such as a cam mechanism or eccentric mechanism) directly converts rotational motion of the camshaft into precise rotational positioning of the valve spool through mechanical linkage, eliminating the need for electrical components and slip rings while maintaining control precision
Solution Approach 2:
The adjusting actuator is designed to perform multiple functions: it provides precise rotational positioning of the valve spool for phase adjustment, maintains the desired phase relationship through self-correction, and eliminates the need for separate electrical motor and slip ring components by integrating these functions into a purely mechanical system
3Measurement precision
If the adjusting actuator operates continuously to maintain phase relationship, then phase accuracy is maintained, but energy consumption increases
Solution Approach 1:
The adjusting actuator operates periodically rather than continuously, engaging only when phase relationship drift exceeds a predetermined threshold detected by the sensor. During normal operation, the spring-loaded valve spool maintains phase accuracy through passive self-correction, allowing the actuator to remain idle and conserve energy while still achieving precise phase control when needed
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 solution minimizes phase relationship drift and eliminates the need for slip rings, providing efficient and reliable control of the camshaft phaser operation by allowing self-correction and precise rotational positioning without continuous motor operation.
Implementation Method 1
The rotational actuator includes a compound planetary gear set centered about a planetary gear set axis and having an input planetary gear set driven by the camshaft phaser input member and an output planetary gear set driven by the input planetary gear set
Implementation Method 2
Engine oil is selectively supplied to one of the advance and retard chambers and vented from the other of the advance chambers and retard chambers by a phasing oil control valve in order to rotate the rotor within the stator
Data Source
AI summary
A camshaft phaser includes a camshaft phaser input member connectable to a crankshaft; a camshaft phaser output member connectable to a camshaft; an intermediate member rotatable relative to the camshaft phaser input member such that rotation of the intermediate member relative to the camshaft phaser input member causes the camshaft phaser output member to rotate relative to the camshaft phaser input member; and a rotational actuator configured to selectively rotate the intermediate member relative to the camshaft phaser input member, the rotational actuator comprising. The rotational actuator includes a compound planetary gear set having an input planetary gear set driven by the camshaft phaser input member and an output planetary gear set driven by the input planetary gear set; and an adjusting actuator connected to the compound planetary gear set.