Crankcase Breather Device Adjacent Coolant Pump
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Solution Overview
Problem
The integration of a breather device with a coolant pump in straddle-type vehicles, such as motorcycles, often requires a larger engine dimension due to the coaxial alignment of the breather housing and impeller member, which protrudes beyond the coolant pump, increasing the engine's overall size.
Innovation Solution
Positioning the breather device further toward the crankcase with a breather housing length along the cylinder centerline larger than the coolant pump, and forming at least a section of the breather housing in a circular shape with its center offset toward the crankcase, allowing the breather device to be adjacent to the coolant pump without protruding beyond it.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the breather device is integrally formed with the coolant pump and coaxially aligned, then the breather device can be compactly integrated, but the engine dimension increases because the breather housing protrudes further than the coolant pump
Solution Approach 1:
The breather housing is repositioned from a coaxial arrangement to an adjacent arrangement along the cylinder center line, utilizing the longitudinal dimension of the cylinder head to accommodate the breather device without increasing the radial engine dimension. The breather housing extends toward the crankcase along the cylinder center line, effectively using available space in the longitudinal direction rather than increasing the overall engine width or height.
Solution Approach 2:
Instead of having the breather housing extend beyond the coolant pump in the radial direction (conventional coaxial design), the invention inverts the spatial relationship by positioning the breather housing adjacent to and extending toward the crankcase along the cylinder center line. This inversion of the spatial arrangement allows the breather device to achieve its required length without increasing the engine's external dimensions.
2Reliability
If the breather housing size is increased to ensure effective air and engine oil separation, then the separation function is improved, but the engine dimension increases
Solution Approach 1:
The breather housing is oriented along the cylinder center line in the longitudinal direction rather than extending radially outward. This dimensional reorientation allows the breather housing to achieve sufficient length for effective gas-liquid separation while being contained within the existing engine envelope, thus improving separation reliability without increasing engine dimension.
Solution Approach 2:
The breather housing is specifically positioned in the region adjacent to the coolant pump and extending toward the crankcase, utilizing the local space availability in this area. By concentrating the separation function in this specific location with appropriate local geometry, the design achieves effective separation without requiring a global increase in engine size.
3Ease of manufacture
If the breather device is positioned coaxially with the cam shaft, then the integration is simplified, but the breather housing must protrude beyond the coolant pump increasing engine size
Solution Approach 1:
The design transitions from a coaxial arrangement (radial alignment) to an adjacent arrangement (longitudinal alignment along the cylinder center line). This dimensional change simplifies the manufacturing by allowing the breather housing to be positioned in the available longitudinal space without complex radial alignment requirements, while avoiding the protrusion problem that would increase engine dimension.
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 configuration maintains the engine's original dimensions and capacity without reducing the breather housing capacity, ensuring efficient gas and oil separation while allowing the cam shaft to pass through, thus preventing engine size increase.
Implementation Method 1
the breather housing in which air and engine oil are separated from the blow-by gas
Implementation Method 2
The breather device has a generally cylindrical shaped breather housing (labyrinth) in which air and engine oil are separated from the blow-by gas
Implementation Method 3
the breather housing can also be cooled by the coolant
Implementation Method 4
the breather housing can also be cooled by the coolant
Data Source
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AI summary
A straddle-type vehicle includes: a swing type engine unit (40) that has a crankcase (90), a cylinder (80), and a cylinder head (70) in which a cam shaft (73) is disposed; a cooling water pump (74) that is provided in the cylinder head (70) and includes an impeller (74a) that is rotatably connected to the cam shaft (73) and supplies cooling water to cooling water channels; and a breather device (75) which is disposed adjacent to the cooling water pump (74) and through which an impeller shaft (74b) passes. The breather device (75) includes a breather housing (S1) that has a length along the cylinder center line (C1) that is larger than that of the cooling water pump (74). The breather housing (S1) is positioned further toward the crankcase (90) with respect to the cam shaft (73).