Fuel Injection Valve Throttled Sealing Gap
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Solution Overview
Problem
Existing fuel injectors for diesel engines face challenges in manufacturing due to the need for tight tolerances, leading to high costs and difficulties in controlling the end of the injection process due to adhesive forces when the high-pressure inlet is closed.
Innovation Solution
Designing the sealing surface of the head and the intermediate valve seat to create a throttled fluid connection when closed, allowing for a radial throttle gap that increases axially, enabling larger tolerances in manufacturing and reducing adhesive forces, thus improving control over the injection process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tight sliding fit is used to separate the high-pressure inlet from the valve chamber, then sufficient separation and sealing are achieved, but manufacturing cost increases due to very tight tolerances (a few microns) required for the shank and bore
Solution Approach 1:
The patent changes the geometric parameters of the sealing surfaces by introducing a throttling passage with a throttle gap between the head and intermediate valve seat. This allows the sliding fit tolerance to be relaxed from microns to hundredths of a millimeter while maintaining sealing performance through the throttling effect that compensates for the larger clearance.
Solution Approach 2:
The patent introduces a throttling passage as an intermediary element between the high-pressure inlet and the valve chamber. This throttling passage, formed by the throttle gap between the head and intermediate valve seat, acts as a mediator that allows larger tolerances in the sliding fit while maintaining the necessary separation and sealing functions.
2Reliability
If the high-pressure inlet is completely closed with extensive contact between the sealing surface of the head and the intermediate valve seat, then sealing is improved, but adhesive forces increase making it difficult to open the intermediate valve again, deteriorating timing precision
Solution Approach 1:
The patent changes the contact parameters between the sealing surfaces by creating a throttling passage with a controlled throttle gap. This reduces the contact area from extensive surface contact to a restricted annular region, thereby reducing adhesive forces while maintaining sealing performance through the throttling effect.
Solution Approach 2:
The patent applies local quality by creating a specific throttling region with a controlled gap between the head and intermediate valve seat. The sealing function is localized to this throttling passage rather than requiring extensive contact across the entire sealing surface, reducing adhesion in the opening process while maintaining sealing where needed.
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 for cost-effective manufacturing with larger tolerances while maintaining precise control over the injection process, ensuring timely termination of fuel injection without being hindered by adhesive forces.
Implementation Method 1
the sealing surface of the head and the surface of the intermediate valve seat are designed in such a way that they create a throttled fluid connection between the high-pressure inlet and the sliding fit when the intermediate valve is in the closed position
Data Source
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AI summary
The control apparatus (88) of a fuel injection valve comprises a mushroom-shaped intermediate valve member (56), which is guided in an intermediate element (94) with a sliding fit (94''). Together with a guide sleeve (78) and the lower surface of the intermediate element (94), the injection valve member (28), which has a control plunger (28'), for opening and closing injection openings so as to implement intermittent injection processes defines a control space (54). An outlet element (114) is located between the intermediate element (94) and the housing body (116) and delimits a valve space (70), which is hydraulically connected to the face of the stem (58) of the mushroom-shaped intermediate valve member (56). The intermediate valve member comprises a stem (58), which is guided in the intermediate element (94) with a sliding fit, and a head (60), which rests with the sealing surface (61) thereof at least partially against a surface (57) of an intermediate valve seat (59) configured on the intermediate element (94) in the closed position of the intermediate valve member (56) in order to separate the high pressure inlet (96) from the control space (54), wherein the sealing surface (61) of the head (60) and the surface (57) of the intermediate valve seat (59) are designed such that they create a throttled fluid connection between the high pressure inlet (96) and the sliding fit in the closed position of the intermediate valve (56').