Hydraulic Camshaft Phaser Valve Spool Flow Control
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Solution Overview
Problem
Existing camshaft phasers face limitations in phasing rate due to restricted oil flow, which affects control stability, and previous solutions either prioritize flow rate over stability or vice versa.
Innovation Solution
A camshaft phaser design featuring an annular groove with a valve spool that varies flow area between the valve bore and passages, allowing controlled oil flow into and out of advance and retard chambers, ensuring a balanced phasing rate and stability by initially providing a low flow rate followed by a rapid increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If circular advance and retard passages extend radially outward from the valve bore, then control stability is improved through gradual flow increase, but maximum flow rate is limited thereby restricting phasing rate
Solution Approach 1:
The flow path is segmented into two distinct components: circular passages that provide gradual flow increase for stability, and radial grooves that provide additional flow area for higher phasing rates. This segmentation allows each component to fulfill its specific function without compromising the other.
Solution Approach 2:
The invention merges the circular passage configuration with radial groove features to create a hybrid flow path. The circular passages and radial grooves work together to provide both gradual flow control and increased maximum flow area, resolving the contradiction between stability and phasing rate.
2Productivity
If circumferential grooves extend radially outward from the valve bore, then maximum flow rate is increased for higher phasing rates, but control stability decreases due to rapid flow increase
Solution Approach 1:
The flow path is segmented into two distinct components: circular passages that provide gradual flow increase for stability, and radial grooves that provide additional flow area for higher phasing rates. This segmentation allows each component to fulfill its specific function without compromising the other.
Solution Approach 2:
Different sections of the flow path have different geometric characteristics: circular passages provide gradual flow control in one region, while radial grooves provide rapid flow expansion in another region. This local differentiation allows the system to achieve both stability and high phasing rate.
3Productivity
If the passage width is increased to provide greater flow area, then phasing rate is improved, but control stability may be compromised due to reduced flow control precision
Solution Approach 1:
The flow path is segmented into two distinct components: circular passages that provide gradual flow increase for stability, and radial grooves that provide additional flow area for higher phasing rates. This segmentation allows each component to fulfill its specific function without compromising the other.
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
The design achieves a balanced phasing rate and control stability by gradually increasing oil flow, optimizing the phasing process between the crankshaft and camshaft while maintaining stability.
Implementation Method 1
a valve spool which moves along the axis within the valve bore between an advance position and a retard position, the valve spool having a land which varies a flow area between the valve bore and the annular groove and between the valve bore and the passage
Data Source
AI summary
A camshaft phaser includes an input member and an output member defining an advance chamber and a retard chamber; a valve body having a valve bore which extends along an axis, an annular groove extending radially outward from the valve bore and having a first width in the direction of the axis, and a passage which opens into the annular groove and which extends from the valve bore through the valve body radially outward from the valve bore such that the passage has a second width in the direction of the axis that is greater than the first width of the annular groove. The camshaft phaser also includes a valve spool which moves along the axis within said valve bore, the valve spool having a land which varies a flow area between the valve bore and the annular groove and between the valve bore and the passage.