Offset Valve Seat Design for Intake Tumble Flow
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Solution Overview
Problem
The existing internal combustion engine designs, such as those described in JP 2016-180359 A, face challenges in achieving optimal intake efficiency and generating a large tumble flow due to the placement of the edge portion in the intake port, which reduces the effective opening area and leads to air flow hindering the tumble flow generation.
Innovation Solution
The design incorporates an annular valve seat with a linear edge portion where the port surface and seat surface contact, ensuring the intake air moves straight and minimizing flow to the outer peripheral side gap, while maintaining adequate rigidity by offsetting the center of the outer peripheral surface of the valve seat from the center of the seating portion, thus optimizing the intake efficiency and tumble flow generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the edge portion is disposed at a position apart from the valve seat to avoid interference, then the valve seat can be properly installed, but the effective opening area of the intake port decreases
Solution Approach 1:
The valve seat is designed with an asymmetric structure where the port surface and seat surface are offset from each other. The port surface is positioned closer to the combustion chamber while the seat surface is positioned farther away, creating an asymmetric configuration that allows the edge portion to be located at an optimal position that balances effective opening area with valve seat installation reliability.
2Reliability
If the edge portion is disposed further inside than the inner peripheral surface of the valve seat, then the valve seat installation is ensured, but the intake efficiency decreases due to reduced effective opening area
Solution Approach 1:
The invention introduces a dimensional offset between the port surface and seat surface, transforming the traditional planar alignment into a three-dimensional asymmetric configuration. This dimensional change allows the edge portion to be positioned at an optimal location that simultaneously ensures valve seat installation stability and maintains adequate effective opening area for high intake efficiency.
3Ease of operation
If the inner wall of the intake port forms a gentle curve to guide air flow, then the air flow direction is controlled, but the amount of intake air heading for the outer peripheral side gap increases
Solution Approach 1:
The invention applies different surface characteristics to different regions of the intake port. The port surface is designed with specific local qualities (smoothness, curvature, orientation) that are optimized for guiding air flow toward the central side gap rather than the outer peripheral side gap, while maintaining overall ease of operation for air flow direction control.
Data Source
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Figure 3
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AI summary
An internal combustion engine includes a cylinder head (12), a valve seat (20), and an intake valve (22). The valve seat (20) is provided with a port surface (30) and a seat surface (32) having end portions in contact with each other on an outer peripheral side of a combustion chamber (18). The port surface (30) is a surface smoothly connected to a wall surface of an intake port (14) and having a normal vector having a direction away from the combustion chamber (18). The seat surface (32) is a surface formed to include a seating portion (34) and having a normal vector having a direction approaching the combustion chamber (18). A center (44) of an outer peripheral surface (42) of the valve seat (20) is offset from a center (40) of the seating portion (34) to the port surface (30) side.