Outboard Motor Shift Unit With Intermediate Shaft For Oil Pump
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Solution Overview
Problem
Existing outboard motor configurations face challenges in operating accessories like oil and water pumps regardless of the shift position, leading to difficulties in feeding oil and maintaining efficient steering and gliding performance due to interference between the water pump and pilot shaft.
Innovation Solution
The outboard motor design includes a shift unit with a driving gear, driven gear, and intermediate gear that ensures continuous rotational power transmission, allowing the oil and water pumps to operate independently of the shift position, and positions the water pump behind the shift unit to reduce interference and maintain a shorter distance between the drive shaft and pilot shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the water pump is provided over the shift unit to avoid interference with the pilot shaft, then the distance between the drive shaft and pilot shaft increases, but the moment of inertia increases and steering performance degrades
Solution Approach 1:
The water pump is repositioned from a vertical arrangement (over the shift unit) to a horizontal arrangement (in front of the shift unit along the drive shaft axis). This dimensional change allows the water pump to be positioned in a different spatial plane, avoiding interference with the pilot shaft while maintaining a compact overall structure and preserving steering performance.
2Device complexity
If the oil pump is operated by receiving rotational power transmitted via the inner shaft connected to the second input shaft, then the structure is simplified, but the oil pump cannot operate when the shift position is set to neutral
Solution Approach 1:
An intermediate shaft is introduced as a mediator between the first input shaft and the oil pump. The intermediate shaft rotates in synchronization with the first input shaft and transmits rotational power to the oil pump independently of the shift unit's engagement state. This allows the oil pump to operate continuously regardless of whether the shift unit is in neutral or engaged position.
3Object-affected harmful factors
If the distance between the drive shaft and pilot shaft is increased to avoid interference, then the water pump can be positioned without interference, but the length from pilot shaft to center of outboard motor increases
Solution Approach 1:
The water pump is repositioned along the drive shaft axis (horizontal dimension) rather than increasing the vertical distance from the pilot shaft. This allows the water pump to be placed in front of the shift unit in the axial direction, avoiding interference with the pilot shaft while maintaining a compact radial footprint and preserving the moment of inertia characteristics.
Data Source
AI summary
An outboard motor includes a drive shaft that transmits rotational power from an engine, a shift unit provided in the middle of the drive shaft, and a water pump that feeds a coolant to the engine. The drive shaft has a first input shaft that receives rotational power transmitted from the engine and a second input shaft that receives rotational power transmitted from the first input shaft. The shift unit has an upper gear rotating in synchronization with the first input shaft, an intermediate gear meshing with the upper gear at all times, and an intermediate shaft extending to the rear side from the intermediate gear and rotating in synchronization. The oil pump as an accessory is operated by the rotational power transmitted to the intermediate shaft.