Fuel Injection Valve High-Pressure Fluid Force Control
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Solution Overview
Problem
Fuel injection valves struggle to maintain valve opening under high fuel pressures, as the fluid force exceeds the valve opening force, making it difficult to keep the needle valve open and closed effectively, especially when operating at pressures up to 45 MPa with a normal maximum fuel pressure of 35 MPa.
Innovation Solution
The fuel injection valve is designed with different curvature radii between the guide and seat portions, allowing for independent adjustment of the seat diameter to reduce fluid force, ensuring the valve can remain open under high pressure without altering the guide portion's inner diameter, thus maintaining efficient operation and reducing manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the seat diameter is increased to allow the valve to remain open under high fuel pressure, then the valve opening reliability is improved, but the fluid force increases causing the valve to fail to close properly
Solution Approach 1:
The valve body end portion is segmented into distinct functional zones: a guide portion with a first curvature radius for accurate valve body guidance, and a seat portion with a second curvature radius optimized for pressure balance. This segmentation allows independent optimization of each zone's curvature radius to resolve the contradiction between maintaining valve opening under high pressure and controlling fluid force for proper valve closure.
Solution Approach 2:
Different curvature radii are applied to different local regions of the valve body end portion. The guide portion has a first curvature radius (R1) while the seat portion has a second curvature radius (R2), where R1 ≠ R2. This local quality differentiation enables the guide portion to provide accurate axial guidance while the seat portion maintains pressure balance, resolving the force contradiction.
2Reliability
If the curvature radius of the valve body end portion is changed to reduce fluid force, then the valve closure reliability is improved, but the guide accuracy deteriorates
Solution Approach 1:
The valve body end portion is divided into a guide portion and a seat portion with different curvature radii. The guide portion maintains its first curvature radius for accurate guidance, while the seat portion uses a different second curvature radius for optimized pressure balance and closure reliability, eliminating the need to compromise guide accuracy.
Solution Approach 2:
The guide portion and seat portion are assigned different local geometric properties (curvature radii) according to their specific functional requirements. The guide portion's first curvature radius ensures manufacturing precision and guide accuracy, while the seat portion's second curvature radius optimizes closure reliability, resolving the contradiction between these two requirements.
3Ease of manufacture
If the valve body end portion is given a uniform spherical shape, then the manufacturing process is simplified, but the ability to independently optimize guide and seat functions is lost
Solution Approach 1:
Rather than using a uniform spherical shape, the valve body end portion is segmented into a guide portion and a seat portion with different curvature radii. This segmentation maintains relative manufacturing simplicity while enabling independent optimization of guide accuracy and pressure balance functions, resolving the contradiction between ease of manufacture and adaptability.
4Force
If the inner diameter of the guide portion is reduced to reduce fluid force, then the fluid force decreases improving valve control, but the guide portion's structural strength is compromised
Solution Approach 1:
The guide portion and seat portion are segmented with different curvature radii. The guide portion maintains its structural integrity with its first curvature radius and dimensions, while the seat portion's different second curvature radius optimizes fluid force characteristics. This segmentation allows the guide portion to maintain strength while the overall valve achieves reduced fluid force through the seat portion design.
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 allows the fuel injection valve to maintain valve opening under high fuel pressures, reducing fluid force and preventing leakage, while also enabling increased fuel injection rates and cost-effective production by allowing independent adjustment of the seat diameter without changing the guide portion's dimensions.
Implementation Method 1
a sliding surface of a guide ring makes contact with a guide surface of the core, in which the sliding surface has a spherical shape, the guide ring constitutes the valve body, and the guide surface has a smooth shape. That is, the sliding surface of the guide ring has the spherical shape not distorted, and even if the valve body is inclined relative to the guide surface of the core, the guide ring constituting the valve body is slidably held in an axial direction.
Implementation Method 2
the sliding surface of the guide ring has the spherical shape not distorted, and even if the valve body is inclined relative to the guide surface of the core, the guide ring constituting the valve body is slidably held in an axial direction. Thus, abrasion is hardly caused between the guide surface of the core and the sliding surface of the guide ring, and sliding resistance of the valve body can be inhibited from being changed with time.
Data Source
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AI summary
Recent exhaust gas regulation requires reduction of an amount and quantity of particulate matter included in an exhaust gas, and a normal maximum fuel pressure may be increased to approximately 35MP. When the normal maximum fuel pressure is 35 MPa, a fuel injection valve is required to work for example at a pressure up to 45 MPa. In such a condition, a fluid force may exceed a valve opening force depending on a seat diameter, and a needle valve cannot be kept open and closed, when opening thereof is required. In order to solve the above problems, a fuel injection valve according to the present invention includes a valve seat portion, a valve body which is seated on or separated from the valve seat portion, an injection hole which is formed on a downstream side from the valve seat portion, and a guide portion which is formed on an upstream side from the valve seat portion seating a valve body seat portion of the valve body to guide a guided portion on a downstream side of the valve body, in which the valve seat portion is formed to have a dimension in a crossing direction crossing an axial direction of 0.4 to 0.8 times a dimension of the guide portion in the crossing direction.