Valve Timing Bolt Deformation via Partition Cutting
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Solution Overview
Problem
In valve opening and closing timing control apparatuses for internal combustion engines, the bolt tends to deform due to circumferential tensile deformation, leading to reduced reliability and toughness when subjected to axial forces, especially when made from the same metal material as the partition body.
Innovation Solution
A valve opening and closing timing control apparatus with a partition body that includes a press-fit portion with a cutting feature to cut the inner peripheral surface of the bolt, preventing deformation by creating a clearance and enhancing the bolt's structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the bolt is made from the same metal material as the partition body, then the manufacturing process is simplified, but the bolt deforms due to circumferential tensile deformation when press-fitted
Solution Approach 1:
A cutting portion is provided in advance on the inner peripheral surface of the bolt at the press-fit location. This preliminary cutting action prevents the bolt from deforming during the press-fitting process by creating a clearance that accommodates the press-fit deformation, thereby maintaining manufacturing precision while using the same material for both bolt and partition body.
2Manufacturing precision
If the strength of the bolt is increased to suppress deformation, then the bolt deformation is reduced, but the reliability and toughness of the bolt are reduced
Solution Approach 1:
Instead of increasing the overall strength of the bolt, a cutting portion is locally provided only at the press-fit location on the inner peripheral surface. This local modification allows the bolt to maintain its original material properties and overall strength while preventing deformation only where needed during press-fitting, thus preserving reliability and toughness.
3Manufacturing precision
If the clearance between the bolt and other members is set considering deformation, then the bolt deformation is accommodated, but the structural integrity is compromised
Solution Approach 1:
The cutting portion is created in advance on the inner peripheral surface to prevent deformation during press-fitting. This preliminary action eliminates the need to design larger clearances to accommodate deformation, thereby maintaining tight clearances and preserving the structural integrity and strength of the bolt while still allowing for proper fit.
Data Source
AI summary
A valve opening and closing timing control apparatus includes: a driving side rotor synchronously rotating with a crankshaft of an engine; a driven side rotor disposed coaxially with the driving side rotor and synchronously rotating with a camshaft in the internal combustion engine; a fluid pressure chamber formed on at least one of the driving side and driven side rotors, and partitioned into advance angle and retard angle chambers; a bolt disposed coaxially with a rotary axis of the driven side rotor, connecting the driven side rotor and the camshaft, and including a cylindrical portion coaxial with the rotary axis; and a partition body including a press-fit portion press-fitted into the cylindrical portion, and partitioning the cylindrical portion into first and second flow passages for use for feeding and discharging working fluid to and from the fluid pressure chamber, wherein the press-fit portion is provided with a cutting portion.