Camshaft Timing Pin Alignment Through a Cam Bushing
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Solution Overview
Problem
Current methods for timing the angular position of a camshaft relative to a crankshaft in internal combustion engines are complex, labor-intensive, and costly, requiring tight manufacturing tolerances and multiple tools.
Innovation Solution
A system utilizing a timing pin and cam bushing to align and secure the camshaft and crankshaft in predetermined positions within the engine, allowing for quick and tool-free installation and reducing the need for additional machined geometry and tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If adjusting pins are screwed into the crankcase and camshaft to hold them in immovable positions, then the timing alignment is achieved, but the manufacturing tolerances must be very tight and skilled labor is required
Solution Approach 1:
A timing pin is introduced as an intermediary component that mediates between the crankshaft and camshaft alignment process. The timing pin fits into aligned openings in both components, serving as a temporary mechanical mediator that ensures precise timing alignment without requiring tight tolerances in the main bearing holes or skilled threading operations.
Solution Approach 2:
The timing pin is designed as a simple, inexpensive, disposable component that is used only during assembly to establish timing alignment. After the timing is set and the chain/gear drive is fastened, the timing pin is removed and discarded, having served its purpose of ensuring accurate alignment without requiring expensive precision machining or skilled labor.
2Reliability
If screws are threadably inserted into holes to lock the crankshaft and camshaft, then the timing is fixed, but many tools are necessary and costs increase
Solution Approach 1:
The timing pin extraction removes the complexity of threaded fastening systems. Instead of using screws that require threading tools, hole alignment, and torque control, the solution extracts only the essential function of holding the components in fixed positions during assembly, achieving timing stability through simple pin insertion and removal.
3Measurement precision
If tight manufacturing tolerances are used for holes to precisely locate and align openings, then the timing accuracy is improved, but the labor cost and manufacturing complexity increase
Solution Approach 1:
The invention changes the tolerance parameters from tight to loose by using the timing pin as a alignment reference. Instead of requiring tight tolerances in the bearing holes themselves, the system allows larger tolerances because the timing pin opening provides the precise reference location, decoupling the tolerance requirements from the main structural components.
Data Source
AI summary
A system for timing a crankshaft and a camshaft in an internal combustion engine having a cylinder head structure with a timing pin hole and a camshaft cavity. The camshaft has a first opening that extends from an outer annular wall of a first shaft towards a longitudinal axis. A cam bushing having a bushing clearance hole is inserted into the camshaft cavity and the camshaft is assembled with the cam bushing and cylinder head structure to align the bearing clearance hole with first opening of the camshaft. A timing pin is inserted through the timing pin hole, bushing clearance hole, and first opening of the camshaft to position the camshaft in a camshaft timing position. The crankshaft is rotated to a crankshaft timing position either before or after the camshaft is rotated for setting a static timing of the crankshaft and camshaft, and the timing pins are removed.