Tube Spring Recess Design for Uniform Actuator Load Distribution
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Solution Overview
Problem
Existing tube springs used to prestress piezoelectric or magnetostrictive actuators in motor vehicle technology, such as fuel injection valves, experience uneven loads and deformations both circumferentially and longitudinally, leading to inefficient stress distribution and potential mechanical issues.
Innovation Solution
A tube spring design featuring recesses with varying cross-sectional dimensions on both the outer and inner surfaces, where the maximum longitudinal and transverse extents differ, allowing for structural strengthening and stress distribution optimization, with recesses arranged alternately to compensate for uneven loads along the circumference and length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform recesses are used in the tube spring, then manufacturing is simple, but uneven loads and deformations occur in the longitudinal and transverse directions
Solution Approach 1:
The patent applies local quality by varying the transverse extent of recesses based on their position along the longitudinal axis. Recesses near abutting edges have different dimensions than those in the middle section, creating localized structural variations that compensate for uneven load distribution. This is achieved by punching recesses with different transverse extents at different longitudinal positions, strengthening or weakening specific portions of the tube spring to evenly distribute stresses and strains both circumferentially and longitudinally.
2Device complexity
If abutting edges are not welded, then manufacturing complexity is reduced, but uneven loads and deformations occur along the circumference
Solution Approach 1:
The patent applies asymmetry by intentionally creating non-uniform recess patterns that are asymmetric with respect to the abutting edges. The recesses are strategically positioned and dimensioned to compensate for the asymmetry introduced by unwelded abutting edges. This asymmetric recess arrangement creates a load distribution pattern that balances the structural weaknesses at the abutting edges, achieving even stress distribution without requiring welding.
3Reliability
If recesses with varying transverse extents are used, then stress distribution is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by systematically varying the transverse extent of recesses as a function of their longitudinal position. This creates a gradient or stepped pattern of recess dimensions that optimizes stress distribution. The parameter variation is designed to be manufacturable, with discrete size changes that can be achieved through standard punching tools, balancing the need for stress distribution optimization with practical manufacturing capabilities.
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 effectively distributes uneven loads and deformations across the tube spring, enhancing its structural integrity and reducing mechanical stress, thereby improving the prestressing efficiency of piezoelectric or magnetostrictive actuators.
Implementation Method 1
The hollow body is designed as an elastic hollow body that prestresses the piezoelectric actuator located therein
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
The invention relates to a tubular spring (8) for receiving and pretensioning a piezoelectric or magnetostrictive actuator (2) of an actuator unit (1) that is in particular suited for actuating a fuel injector valve in internal combustion engines, wherein the tubular spring (8) comprise at least two types of recesses (A, B, C), each comprising different maximum lateral extensions (hA, hB, hC) in the longitudinal direction of the tubular spring (8). The tubular spring (8) is designed to comprise a uniform load distribution about the circumference of the tubular spring (8) even without welding the longitudinal sides thereof abutting one another (butt edges 42).