High Pressure Fuel Accumulator Diffusion Bonding
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Solution Overview
Problem
Current common rail systems for high-pressure fuel injection in diesel engines face challenges in withstanding internal pressures above 120 MPa due to joint defects and fatigue breakage, leading to reliability issues and increased production costs, as existing methods like hot forging and machining compromise shapeability and processing complexity.
Innovation Solution
The use of liquid phase diffusion bonding or other high-temperature joining methods to assemble fuel injection accumulator-distributors with specifically designed holders and rail bodies, featuring guide grooves, partial cone-shaped skirts, and metal rings to apply compressive stress, enhancing joint strength and durability against internal pressure fatigue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hot forging and machining are used to form common rail integrally, then strength and reliability are improved, but shapeability deteriorates and processing becomes difficult
Solution Approach 1:
The common rail is divided into multiple parts (rail body, holders, pipe attachment components) that are manufactured separately using liquid phase diffusion bonding. This segmentation allows each part to be optimized independently for both strength and manufacturability, resolving the contradiction between integral forming requirements and shapeability.
Solution Approach 2:
The invention changes the manufacturing parameter from conventional hot forging temperatures to liquid phase diffusion bonding temperatures, enabling parts to be joined at temperatures where material flow and bonding occur simultaneously. This parameter change allows complex shapes to be achieved while maintaining joint strength.
2Strength
If hot forging and machining are used to form common rail integrally, then strength is improved, but device complexity increases
Solution Approach 1:
By segmenting the common rail into standardized modules (rail body, holders, pipe attachments), the invention reduces processing complexity. Each module can be manufactured using standard liquid phase diffusion bonding processes, avoiding the need for complex integral forging and machining operations.
Solution Approach 2:
The holders are designed as universal components that can be attached to the rail body at multiple positions. This multi-functionality reduces the overall device complexity by using standardized attachment mechanisms rather than custom-integrated features for each pipe connection.
3Ease of manufacture
If liquid phase diffusion bonding is used to join parts, then shapeability is improved, but joint defects may occur reducing reliability
Solution Approach 1:
The invention applies preliminary action by pre-heating the parts to bonding temperature before joining, and by preparing the joint surfaces with appropriate roughness and cleanliness. This preliminary preparation ensures proper diffusion bonding occurs without defects, maintaining reliability while enabling complex shapes.
Solution Approach 2:
The invention uses an intermediary bonding layer or atmosphere control during liquid phase diffusion bonding to prevent oxidation and contamination at the joint interface. This intermediary measure ensures defect-free joints while maintaining the shapeability advantages of the bonding process.
4Reliability
If high strength steel material is used, then reliability is improved, but ease of manufacture deteriorates
Solution Approach 1:
The invention changes the manufacturing parameter from room temperature or conventional forging temperatures to elevated liquid phase diffusion bonding temperatures. At these elevated temperatures, high strength steel materials become more ductile and easier to form and join, resolving the contradiction between material strength and manufacturability.
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 approach significantly improves the reliability and durability of high-pressure fuel injection systems by compensating for joint defects and ensuring long-term resistance to internal pressure fatigue, while maintaining shapeability and reducing production costs.
Implementation Method 1
joining the holder and the rail body by liquid phase diffusion bonding or another joining method at a 1000° C. or higher temperature
Implementation Method 2
a metal ring which plastically deforms and is press-fit into a clearance... whereby a constant compressive stress is applied cold to the joint face
Data Source
AI summary
An automobile-use high pressure fuel injection accumulator-distributor comprised of a body of an automobile-use high pressure fuel injection accumulator-distributor to which pipe attachment holders for attaching fuel distribution pipes for distributing fuel to injection nozzles at an equal pressure are joined by liquid phase diffusion bonding etc., wherein each holder is comprised of a tube part at the pipe side and a partial cone-shaped skirt at the end of the rail body side, each holder skirt has a shape spreading in a partial cone shape toward the joint face end with an angle from the holder tube part side face of 10° or more in a range of a length of 2 mm or more in the holder axial direction at the outer circumference of the end of the holder at the joint face side, the rail body has holder joint position determining guide grooves at its holder joint positions, each guide groove is comprised of a groove inner circumferential wall of a size enabling engagement with a holder joint inner circumference, a groove bottom forming a joint face with the holder, and a groove outer circumferential wall of a partial cone shape bulging out to the inner side parallel to the holder skirt from the groove bottom toward the holder side at a depth of 2 mm or more, and a metal ring is plastically deformed and press-fit into a clearance of 0.5 mm or more between each holder skirt and the groove outer circumferential wall and parallel to the joint face.