Variable Valve Timing Rotor with Equalized Grinding Surfaces
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Solution Overview
Problem
The complex and asymmetrical shape of rotors in variable valve timing engines makes it difficult to evenly grind the axial faces, leading to longer grinding times, uneven material removal, and reduced dimensional stability due to differing surface areas.
Innovation Solution
The method involves forming recessed surfaces on the axial sides of the rotor to equalize the surface areas being ground, allowing for simultaneous grinding of parallel planar surfaces with the recessed surfaces offset to balance the surface areas, thereby facilitating more efficient and accurate finishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If simultaneous grinding of both axial faces is performed, then productivity is improved, but manufacturing precision deteriorates due to uneven material removal from unequal surface areas
Solution Approach 1:
The invention intentionally introduces asymmetry by creating recessed areas on one or both axial faces of the rotor. These recesses are designed to reduce the ground surface area of larger faces, thereby balancing the surface areas that contact the grinding wheels. This controlled asymmetry in the workpiece geometry enables simultaneous grinding of both faces with uniform material removal rates, resolving the contradiction between productivity and precision.
2Manufacturing precision
If the larger axial face is ground longer to achieve required flatness, then manufacturing precision is improved, but loss of time increases
Solution Approach 1:
The recessed areas are created during the powder metallurgy forming process, before the grinding operation. This preliminary shaping of the surface geometry ensures that when simultaneous grinding occurs, both faces have equal surface areas to be ground, eliminating the need for extended grinding time on larger faces while maintaining required flatness specifications.
3Shape
If one axial face has significantly larger surface area, then the complex rotor geometry is maintained, but ease of operation deteriorates due to difficult-to-control grinding process
Solution Approach 1:
The invention applies local modification to specific regions of the axial faces by creating recessed areas only where needed. This local quality change reduces the surface area of larger faces without altering the overall rotor geometry or affecting other critical dimensions. The recesses are strategically positioned to balance ground surface areas while preserving the functional geometry of the rotor, thereby improving ease of operation during grinding.
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 approach reduces the time and variability in the grinding process, enhances dimensional control, and improves the throughput of rotor production by ensuring more uniform part-to-part variance, allowing for faster and more precise grinding of the rotor surfaces.
Implementation Method 1
compacting a powder metal material in a tool and die set to form a powder metal compact
Implementation Method 2
sintering the powder metal compact to form a sintered powder metal part
Implementation Method 3
grinding the sintered powder metal part... During the step of grinding, this pair of planar surfaces are ground simultaneously
Data Source
AI summary
A rotor for a variable valve timing engine is disclosed in which the opposing planar surface(s) of the rotor have one or more recesses formed therein in order to balance, equilibrate, or equalize the planar surface areas on the opposing surfaces. Among other things, this can improve the accuracy and efficiency with which the rotor is ground during a related method of manufacturing the rotor.