Piezoelectric Actuator Contact Plates Embossed Edges
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Solution Overview
Problem
Piezoelectric actuators in internal combustion engine injectors face challenges with fractures in contact plates under high vibrational stress due to rough cut edges, leading to potential failures and increased manufacturing costs.
Innovation Solution
The contact plates are produced with partially embossed stamped edges, introducing compressive stresses and rounded edges to enhance robustness, and the embossing is focused on metal sections most susceptible to vibrational stress, with a curvature radius transition to minimize notch effects, and a plastic body is spray-molded onto the bent contact plates to secure terminal leads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If contact plates are produced by stamping from sheet metal blank, then manufacturing cost and time are reduced, but stamped edges contain cracks that cause fractures under vibrational stress
Solution Approach 1:
The embossing process is performed as a preliminary action after stamping but before final assembly. By embossing the stamped edges beforehand, compressive stresses and roundings are introduced in advance to prevent crack propagation during subsequent vibrational stress, thereby maintaining both manufacturing efficiency and product reliability
Solution Approach 2:
The harmful cracks in the stamped edges are converted into a benefit through embossing. The embossing process transforms the vulnerable stamped edges by introducing compressive stresses that counteract the existing cracks, turning a defect-prone feature into a strengthened component that can withstand vibrational stress
2Reliability
If embossing is applied to all stamped edges, then robustness against fractures is improved, but manufacturing time and costs increase
Solution Approach 1:
Instead of uniformly embossing all stamped edges, the invention applies embossing selectively only to specific metal sections that are particularly subject to vibrational stress due to their geometric shape and location. This localized approach maintains robustness where needed while minimizing additional manufacturing time and costs
Solution Approach 2:
The invention employs partial embossing rather than complete embossing of all edges. By applying embossing only to the extent necessary for critical sections, the solution achieves sufficient reliability improvement without the excessive time and cost investment that would result from universal embossing
3Ease of manufacture
If sharp transitions between embossed and non-embossed sections are created, then manufacturing simplicity is maintained, but fracture risk increases due to notch effect
Solution Approach 1:
The invention introduces curvature radii at the transition zones between embossed and non-embossed sections. This rounding of sharp transitions eliminates stress concentration points that would otherwise create notch effects, thereby reducing fracture risk while maintaining manufacturing simplicity through a straightforward geometric modification
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 solution significantly increases the robustness of contact plates against fractures under vibrational stress, reduces manufacturing time and costs, and ensures reliable operation by preventing terminal lead breakage.
Implementation Method 1
the embossed stamped edges are present at least partially in selected metal sections... the rough cut in the fractional portion of the stamped edges is compensated by the introduction of inherent compressive stresses and roundings
Implementation Method 2
The actuator includes a piezoelectric module having a ceramic body... which is made up of a plurality of adjoining piezoelectric elements
Implementation Method 3
a plastic body is spray-molded onto the bent contact plates to secure terminal leads
Data Source
AI summary
A piezoelectric actuator, in particular for injectors in internal combustion engines, is provided which includes a piezoelectric module including a ceramic body and two end pieces which clamp the ceramic body axially in place, and an electrical connecting element which is secured on the piezoelectric module and which includes two contact plates leading to the ceramic body. To increase the robustness of the connecting element and to avoid fractures in the contact plates under high vibrational stresses, the contact plates are designed as one-piece metal stampings including at least partially embossed stamped edges.