Cylinder Block Water Jacket with Sub-Passage for Pressure Loss Reduction
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Solution Overview
Problem
In cylinder blocks of multicylinder engines, the presence of head bolt bosses near the coolant inlet increases coolant flow velocity and pressure loss due to locally narrowed water jacket passages, making it difficult to reduce pressure loss effectively.
Innovation Solution
The cylinder block design incorporates a main passage and a sub-passage with a widened portion, where the coolant is divided into two streams at a first position between head bolt bosses, allowing part of the coolant to flow between the cylinder bank and the head bolt boss, reducing flow velocity and pressure loss, and preventing coolant stagnation by positioning the inlet between head bolt bosses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the passage width of the water jacket is increased to reduce coolant flow velocity and pressure loss, then pressure loss decreases, but head bolt bosses cannot be displaced from the cylinder due to sealing and vibration requirements, causing locally narrowed portions that increase pressure loss
Solution Approach 1:
The water jacket passage is divided into a main passage and a sub-passage. The sub-passage branches from the main passage at a first position, passes behind the first head bolt boss, and merges back at a second position. This segmentation allows coolant to flow through two separate paths, increasing the effective flow area and reducing flow velocity and pressure loss in the vicinity of the head bolt boss without requiring displacement of the boss from the cylinder.
2Reliability
If head bolt bosses are positioned close to cylinders for sealing and vibration control, then sealing properties and vibration control are improved, but locally narrowed portions are produced in the water jacket that increase pressure loss
Solution Approach 1:
The sub-passage is routed in a different spatial dimension by passing behind the first head bolt boss, effectively utilizing the three-dimensional space around the boss. This allows the coolant flow path to bypass the boss without requiring the boss to be moved from its optimal position for sealing and vibration control, thus maintaining reliability while reducing pressure loss.
3Loss of energy
If the passage width between each cylinder and the corresponding head bolt boss is made large to reduce pressure loss, then pressure loss decreases, but the head bolt boss cannot be largely displaced from the cylinder
Solution Approach 1:
The water jacket passage is divided into a main passage and a sub-passage. The sub-passage branches from the main passage at a first position, passes behind the first head bolt boss, and merges back at a second position. This segmentation allows coolant to flow through two separate paths, increasing the effective flow area and reducing flow velocity and pressure loss in the vicinity of the head bolt boss without requiring displacement of the boss from the cylinder.
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 design reduces the pressure loss of coolant by decreasing flow velocity around the head bolt bosses, enhancing coolant flow efficiency and minimizing stagnation.
Implementation Method 1
a water jacket configured to surround the cylinder bank... coolant passes through between the head bolt bosses and the cylinder bank
Implementation Method 2
a plurality of head bolt bosses for receiving head bolts is formed on the exhaust side and the intake side, respectively, along the cylinder bank. The water jacket is formed so that coolant passes through between the head bolt bosses and the cylinder bank, and flows along the periphery of the cylinder bank
Data Source
AI summary
A water jacket of a cylinder block includes a main passage and a sub-passage. The main passage is formed along the periphery of a cylinder bank, and extends between a plurality of head bolt bosses and the cylinder bank. The sub-passage is formed at a position spaced from the cylinder bank farther than the main passage, to diverge from the main passage at a first position, and join the main passage at a second position downstream of the first position. A first head bolt boss by which coolant flowing from a coolant inlet initially passes is interposed between the main passage and the sub-passage. The first position is located between the first head bolt boss and the coolant inlet. The second position is located between a second head bolt boss by which the coolant passes next, and the first head bolt boss.