Sun Gear Deformation Control in Valve Timing Apparatus
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Solution Overview
Problem
Existing valve timing control apparatuses experience radial deformation of the sun gear due to axial compression, leading to increased friction and noise, which deteriorates performance and durability.
Innovation Solution
The valve timing control apparatus includes a sun gear with through-holes for fixing members and press-fitting parts that distribute deformation, limiting radially inward deformation and misalignment, while maintaining rigidity through strategically placed open parts and press-fitting parts that resist deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the sun gear is press fitted to the radially inner side of press-fitting projections of the driving-side rotatable body, then misalignment of the sun gear is limited, but axial compression force causes radial deformation and expansion of the sun gear
Solution Approach 1:
The sun gear is divided into multiple press-fitting parts arranged circumferentially, each independently press-fitted to the driving-side rotatable body. This segmentation distributes the axial compression force across multiple locations, preventing concentrated stress that would cause radial deformation and expansion of the internally toothed portion.
Solution Approach 2:
Press-fitting projections are strategically positioned at specific circumferential locations on the driving-side rotatable body to provide localized support. This creates areas of enhanced structural integrity where the sun gear is most susceptible to deformation, while maintaining flexibility in other regions.
2Stability of the object's composition
If the sun gear deforms radially inward due to axial compression, then the fitting relationship is maintained, but friction and noise increase deteriorating performance and durability
Solution Approach 1:
The design anticipates axial compression forces that will occur during operation and pre-configures the sun gear with multiple press-fitting parts and corresponding projections to distribute these forces. This prevents excessive radial inward deformation before it can generate harmful friction and noise between the internally toothed portion and planet gears.
Solution Approach 2:
The patent changes the structural parameters of the sun gear by adding multiple press-fitting parts and corresponding projections, transforming it from a single-point fixation to a multi-point distributed fixation system. This parameter change allows the sun gear to maintain dimensional stability under axial compression without generating harmful friction and noise.
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 reduces friction and noise, enhances durability, and maintains the apparatus's performance by controlling deformation and misalignment, thereby improving the overall reliability of the valve timing control system.
Implementation Method 1
the sun gear receives an axial compression force from the bolts and is thereby deformed to expand in the radial direction. At this time, radially outward deformation of the sun gear is interfered by the press-fitting projections of the driving-side rotatable body.
Data Source
AI summary
Bolts are respectively inserted through through-holes of a sun gear and are respectively threadably inserted into threaded holes of a driving-side rotatable body. The bolts are placed on an outer side of a first internally toothed portion of the sun gear in a radial direction and fix the sun gear and the driving-side rotatable body together. The sun gear includes press-fitting parts, each of which is press-fitted to a corresponding one of press-fitting projections of the driving-side rotatable body at a corresponding location that is located between corresponding adjacent two of the bolts in a circumferential direction, and open parts, each of which is placed at a corresponding location that overlaps with a corresponding one of the bolts in the circumferential direction, while a corresponding predetermined space is located adjacent to each of the open parts on an outer side of the open part in the radial direction.