Cylinder Head Water Jacket Rigidity and Pressure Loss
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Solution Overview
Problem
Conventional water jacket structures in cylinder heads face challenges in securing rigidity against explosion loads and suppressing pressure loss associated with cooling water flow.
Innovation Solution
The water jacket structure incorporates a reduced diameter part near reinforcing post formation areas and features inclined, curved surfaces to control cooling water flow, ensuring rigidity and minimizing pressure loss by facilitating vertical flow between cylinders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a water jacket is formed in the cylinder head, then cooling function is provided, but rigidity against explosion load deteriorates
Solution Approach 1:
The water jacket flow passage is segmented into multiple stages (first water jacket and second water jacket) with intermediate flow passages. This segmentation allows strategic placement of reinforcing posts at interfaces between stages, providing structural reinforcement without compromising the overall cooling function. The cooling water flow is divided into multiple paths, enabling rigidity enhancement in specific regions while maintaining cooling efficiency.
Solution Approach 2:
Reinforcing posts are strategically placed at specific locations where rigidity is most needed, such as at the interface between the first and second water jackets and at the communication flow passage. The wall thickness is locally increased at these reinforcing post locations. This local quality approach provides targeted structural reinforcement without adding unnecessary weight or complexity throughout the entire water jacket structure.
2Temperature
If a water jacket is formed in the cylinder head, then cooling function is provided, but pressure loss of cooling water increases
Solution Approach 1:
The cooling water flow passage is divided into multiple stages with intermediate communication passages. This segmentation creates multiple flow paths and reduces the length of individual flow passages, thereby reducing the total pressure loss. The cooling water can flow through shorter segments rather than a single long passage, maintaining cooling efficiency while reducing energy loss.
Solution Approach 2:
The water jacket structure utilizes three-dimensional spatial arrangement with multiple levels (first and second water jackets) connected by communication flow passages. This vertical arrangement in another dimension allows cooling water to flow through a more compact and efficient path, reducing the horizontal flow distance and associated pressure losses while maintaining effective cooling coverage.
3Strength
If reinforcing posts are added to enhance rigidity, then structural strength is improved, but device complexity increases
Solution Approach 1:
The reinforcing posts are merged with the water jacket structure itself, serving dual purposes: providing structural reinforcement and forming part of the cooling water flow passage boundaries. The reinforcing posts are integrated into the wall structure between water jackets, combining structural and functional elements into a unified design, thereby reducing overall device complexity.
Solution Approach 2:
The reinforcing posts serve multiple functions simultaneously: they enhance rigidity against explosion loads, define the boundaries of cooling water flow passages, and create structural interfaces between the first and second water jackets. This multi-functionality reduces the need for separate components, simplifying the overall structure while achieving multiple objectives.
Data Source
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AI summary
A water jacket structure includes: a lower water jacket that is provided inside a cylinder head installed at the top of a cylinder block; and an upper water jacket that communicates with the lower water jacket, and is provided on a side away from the cylinder block than the lower water jacket; wherein the lower water jacket includes, for each space between cylinders: a communication flow passage that communicates with the upper water jacket; and a reinforcing post formation part on which a reinforcing post is installed; wherein the reinforcing post formation part is located on a downstream side in a flowing direction of cooling water along a cylinder arrangement direction than the communication flow passage.