Cam Phaser Helical Bias Spring Square End Retention
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Solution Overview
Problem
Prior art camshaft phasers using helical bias springs face challenges in manufacturing due to the need for axial or radial tangs, which complicate the formation of powdered metal components, increase packaging size, and require additional space for sealing, especially in pulley applications.
Innovation Solution
A helical bias spring with at least one linear region and an adjacent region having a radius of curvature less than the helix, allowing for a 'square-end' design that is easier to form and reduces packaging volume, eliminating the need for axial or radial tangs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If axial or radial tangs are used to anchor the helical bias spring, then the spring can be securely grounded to the phaser components, but the manufacturing complexity increases and powdered metal component formation becomes difficult
Solution Approach 1:
The spring end is formed with a curved contour that complements a corresponding curved recess in the phaser component, eliminating the need for axial or radial tangs. This curved interface provides secure anchoring while being compatible with powdered metal manufacturing processes, as the continuous curved shape can be easily formed without complex die designs required for tang structures.
Solution Approach 2:
Instead of extending the spring end outward as a tang to engage a slot, the invention inverts the approach by creating a recess in the phaser component that receives and anchors the spring end. This reversal of the anchoring geometry simplifies manufacturing while maintaining secure connection.
2Reliability
If axial or radial tangs are used to anchor the helical bias spring, then the spring can be securely grounded, but the packaging volume of the phaser increases
Solution Approach 1:
The spring end is nested within a recess in the phaser component, with the curved spring end fitting into the corresponding curved recess. This nesting arrangement eliminates the need for external tang structures that would increase radial or axial dimensions, thereby reducing the overall packaging volume of the phaser while maintaining secure anchoring.
3Reliability
If radial or axial spring ends are used, then the spring can be anchored to the phaser, but additional seal plates or increased radial packaging volume is required
Solution Approach 1:
The anchoring function and sealing function are merged into a single integrated recess structure. The curved recess in the phaser component simultaneously anchors the spring end and provides a sealed environment, eliminating the need for separate seal plates that would be required with traditional radial or axial tang configurations.
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 solution reduces the size, complexity, and manufacturing cost of camshaft phasers by improving durability, packaging efficiency, and performance through reduced frictional hysteresis and minimal space requirements.
Implementation Method 1
a helical bias spring (100) having at least one linear region (110) and an adjacent region (108) having a radius of curvature less than that of the helix
Implementation Method 2
to counterbalance a portion of the friction torque of the camshaft due to the valve train components (lifters, cam journals, cam driven accessories, etc.)
Data Source
AI summary
A helical phaser bias spring including at least one linear region and an adjacent region having a radius of curvature less than that of the helix. A channel in the phaser receives the linear region of the spring and adjacent region to lock the spring to the phaser at either the rotor or the stator. Preferably, the spring includes two linear regions separated by a bend of about 90°. Additional linear regions are possible, separated by right and/or other angle bends. In a phaser rotor or stator, the geometric shape required to hold a spring end having a flat is easier to form with powdered metal tooling or diecasting than is a circular, radial, or axial shape for receiving a spring tang as in the prior art, the packaging volume required for the spring is smaller, and spring friction is lowered.