Camshaft Phaser Valve Spool Integration
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Solution Overview
Problem
Existing camshaft phasers with check valves add axial length and complexity to the assembly process due to the need for small, hard-to-handle components, which complicates the implementation of the phasing oil control valve.
Innovation Solution
A camshaft phaser design featuring a valve spool with a phasing volume and venting volume, where the valve spool is moveable between advance and retard positions to control oil flow between the advance and retard chambers, and a supply check valve located within the phasing volume to prevent backflow, simplifying the assembly and operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a check valve is included in the camshaft phaser to prevent oil backflow, then oil flow control reliability is improved, but axial length and assembly complexity increase due to small hard-to-handle components
Solution Approach 1:
The check valve functionality is merged into the valve spool assembly itself. The valve spool includes a check valve passage that provides fluid communication between the phasing volume and supply passage, eliminating the need for separate check valve components. This integration maintains oil flow control reliability while significantly reducing assembly complexity and the number of small hard-to-handle parts.
Solution Approach 2:
The valve spool serves multiple functions: it controls oil flow to the advance and retard chambers, provides check valve functionality through its integrated passage, and manages fluid communication between different volumes. This multi-functionality reduces the overall component count and simplifies the assembly while maintaining reliable oil flow control.
2Manufacturing precision
If multiple small components are used to make up the check valve, then oil flow control precision is improved, but ease of manufacture deteriorates due to difficulty in handling and assembling small parts
Solution Approach 1:
The check valve functionality is merged into the valve spool assembly itself. The valve spool includes a check valve passage that provides fluid communication between the phasing volume and supply passage, eliminating the need for separate check valve components. This integration maintains oil flow control reliability while significantly reducing assembly complexity and the number of small hard-to-handle parts.
3Device complexity
If the valve spool design integrates phasing and venting volumes within the valve spool bore, then device complexity is reduced, but manufacturing precision requirements increase due to fluid segregation needs
Solution Approach 1:
The valve spool design integrates both the phasing volume and venting volume within the valve spool bore itself, using the valve spool bore as a multi-functional chamber. This integration reduces device complexity by eliminating separate external volumes while the valve spool's movable positions provide sufficient fluid segregation through its blocking and opening functions, maintaining adequate precision without excessive manufacturing requirements.
Solution Approach 2:
The valve spool's movable design allows dynamic control of fluid communication between the phasing and venting volumes. By moving between positions, the valve spool dynamically blocks or opens fluid pathways, providing effective segregation when needed and communication when needed, thereby reducing static structural complexity while maintaining functional precision.
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 design minimizes axial length and assembly complexity while effectively controlling the phase relationship between the crankshaft and camshaft, enhancing engine performance by allowing precise timing adjustments without the need for additional components.
Implementation Method 1
Oil is supplied to the advance chamber from the phasing volume through the spool phasing passage in order to retard the timing of the camshaft relative to the crankshaft and oil is supplied to the retard chamber from the phasing volume through the spool phasing passage in order to advance the timing of the camshaft relative to the crankshaft
Implementation Method 2
a supply check valve which prevents oil from flowing from said phasing volume to said supply passage
Data Source
Figure 1
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AI summary
A camshaft phaser (12) includes an input member (18); an output member (20) defining an advance chamber (42) and a retard chamber (44) with the input member (18); a valve spool (30) moveable between an advance position and a retard position. The valve spool (30) has a phasing volume (110) and a venting volume (112) defined therein such that the phasing volume (110) is fluidly segregated from the venting volume (112). The valve spool (30) also has a passage (130) providing fluid communication between the phasing volume (110) and the exterior of the valve spool (30). Oil is supplied to the advance chamber (42) from the phasing volume (110) through the passage (130) in order to retard the timing of a camshaft (14) and oil is supplied to the retard chamber from the phasing volume (110) through the passage (130) in order to advance the timing of the camshaft (14).