Heat Exchanger Header Passages for Mechanical Strength
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Solution Overview
Problem
Heat exchangers in motor vehicles face mechanical stress issues due to thermal expansion and deformation, leading to leaks and failure, which are costly and require replacement, with existing designs providing insufficient mechanical strength between tubes and headers.
Innovation Solution
The design features passages in the heat exchanger that are stretched to increase in length and decrease in thickness from the start to the end, providing a larger contact surface when connected, and are made using materials like aluminum and plastic with fluid-tight connections through soldering or adhesive methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the wall thickness of the collecting tube is reduced to minimize material use and cost, then manufacturing cost decreases, but the mechanical strength and reliability of the connection between tubes and header deteriorate
Solution Approach 1:
The invention transitions from a simple puncture hole to a three-dimensional passage structure that extends into the wall thickness direction. The passage has a defined length (L) and varying cross-sectional area, creating a dimensional transition that increases contact surface area between the tube and header without requiring increased wall thickness. This resolves the contradiction by providing enhanced mechanical interlocking and thermal contact while maintaining thin-wall construction.
Solution Approach 2:
The invention changes the geometric parameters of the connection interface by creating passages with varying cross-sectional areas along their length. The passage cross-section transitions from a smaller opening at the tube end to a larger opening at the header end, optimizing both mechanical interlocking strength and thermal contact area. This parameter optimization allows reliable connections in thin-walled structures.
2Reliability
If the contact surface area between tubes and header is increased to improve mechanical strength, then connection reliability improves, but the complexity of the manufacturing process increases
Solution Approach 1:
The invention merges the functions of creating the opening and forming the passage into a single integrated process step. The passage is formed directly during the puncturing or drilling operation by controlling the tool path or using a specialized tool that creates the tapered passage geometry in one action, rather than requiring separate operations for opening creation and passage formation.
Solution Approach 2:
The passage geometry is designed to be self-forming during the insertion process. As the tube is inserted into the header, the tapered passage walls naturally guide and conform the connection, with the varying cross-section providing progressive mechanical interlocking without requiring additional fastening elements or complex assembly operations.
3Strength
If the passage length is increased to provide greater contact surface area, then mechanical strength improves, but the manufacturing precision requirements increase
Solution Approach 1:
The passage is designed with non-uniform cross-sectional area along its length, with the largest cross-section located at the header end where maximum mechanical interlocking is needed. The cross-sectional area gradually decreases toward the tube end, creating a tapered geometry that concentrates the mechanical strength requirements at the most critical location while reducing precision requirements at the insertion end.
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 enhances the mechanical strength and reliability of the heat exchanger, reducing the likelihood of leaks and improving the ability to absorb thermal stresses, thereby increasing the reliability and safety of the motor vehicle air conditioning system.
Implementation Method 1
the thickness of the passages decreases, preferably steadily, from the start of the passages on the wall of the collecting tube to one end of the passages
Implementation Method 2
Heat exchangers are used to transfer heat from one fluid to another fluid
Data Source
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AI summary
The invention relates to a heat exchanger, especially to a heat exchanger for a motor vehicle, comprising a plurality of tubes (2), at least one collecting tube (3) with a wall (8) and openings (13) in the wall (8), supports (7) protruding from the wall (8) in the axial direction of the openings (13) being formed at the openings (13), wherein the tubes (2) in the region of one end (11) of the tubes (2) are disposed partly at the supports (7) and a fluid-tight connection exists between the supports (7) and the tubes (2), so that a fluid can be passed through the tubes (2) and the at least one collecting tube (3), and at least one inlet opening (5) for passing the fluid in and at least one outlet opening (6) for passing the fluid out. The mechanicals stability between the tubes (2) and the at least one collecting tube (3) is to be improved. This objective is accomplished owing to the fact that the thickness (16) of the supports (7) is less than the thickness (17) of the wall (8), especially in the region of the openings (13) of the collecting tube (3).