Crankcase Through-Hole for Balancer Gear Alignment
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Solution Overview
Problem
In conventional internal combustion engines, the alignment of positioning marks for the balancer driving gear wheel and driven gear wheel is difficult to confirm due to the hidden meshing region between crank journal walls, making assembly challenging and costly.
Innovation Solution
An internal combustion engine design with a crankcase featuring a through-hole in one side wall that allows direct visualization of positioning marks on the balancer gear wheels, facilitating alignment confirmation regardless of the engine's form, and ensuring rigidity by equal pitch circle diameters and strategic placement of the through-hole.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the balancer mechanism is disposed between crank journal walls, then the structure is compact and stable, but the meshing region of gear wheels becomes hidden and alignment of positioning marks becomes difficult to confirm
Solution Approach 1:
The patent introduces a new observation dimension by providing a through-hole in the crankcase wall. This allows the positioning marks on the gear wheels to be observed from the outside of the crankcase through the through-hole, transforming the observation path from a hidden internal region to an accessible external view, thereby resolving the contradiction between structural compactness and alignment detectability
2Difficulty of detecting and measuring
If a cutaway portion is provided on the crank web, then positioning marks become visible from the opposite side of the crankcase, but the crankcase structure becomes more complex and rigidity may be compromised
Solution Approach 1:
The patent extracts the observation function from the complex cutaway structure and implements it through a simple through-hole in the crankcase wall. This through-hole provides a direct viewing path to the positioning marks without requiring removal or modification of the crank web structure, thereby achieving positioning mark visibility while maintaining structural simplicity and rigidity
3Ease of operation
If the through-hole is positioned to allow direct observation of positioning marks, then alignment confirmation is facilitated, but the rigidity of the crankcase may be reduced
Solution Approach 1:
The patent applies the local quality principle by providing reinforcement ribs around the through-hole region of the crankcase wall. These ribs locally strengthen the area where the through-hole is provided, compensating for the potential rigidity reduction caused by the hole, while still maintaining the ability to observe positioning marks for easy alignment during assembly
Data Source
AI summary
In an internal combustion engine with a balancer including a crankcase having a pair of wall portions, a crankshaft supported for rotation on the wall portions and having a balancer driving gear wheel provided thereon, and a balancer shaft supported for rotation by the wall portions and having a balancer driven gear wheel provided thereon, both gear wheels are disposed between the wall portions. A positioning mark including a set of marks provided on side faces in the same direction of the gear wheels is disposed near to pitch circles of both gear wheels. At a position opposing to both side faces of the one wall portion on the side opposing to the positioning mark on the pitch circles of both gear wheels, a through-hole extending through the one side wall is provided to permit the positioning mark to be visually observed through the through-hole.