Vehicular Transmission Switch with Nickel-Plated Contacts
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Solution Overview
Problem
Existing vehicular transmission switch systems face issues with reduced contact force over time, increased contact resistance due to oxidation and wear, and decreased reliability during high vibration, leading to inaccurate signal transmission.
Innovation Solution
The solution involves using parallel tracks with lead frames made of stainless steel and coated with bright nickel to reduce contact resistance, combined with leaf springs and cantilever contact arms with specific geometry to maintain consistent contact force and improve vibration resistance, along with a cambered design to lower the actuation force and enhance stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stainless steel spring contact arms and stationary conductive segments are used, then initial contact force is adequate, but over time contact force decreases and contact resistance increases due to oxidation and wear
Solution Approach 1:
The patent applies bright nickel plating to the stainless steel contact surfaces, changing the material surface properties to reduce oxidation and wear. This coating modification maintains low contact resistance and adequate contact force over extended service life, resolving the degradation issue of bare stainless steel contacts.
Solution Approach 2:
The patent uses a composite structure combining stainless steel substrate with bright nickel coating. This composite approach leverages the mechanical strength of stainless steel while adding the corrosion and wear resistance of nickel plating, thereby maintaining reliable electrical contact throughout the component's service life.
2Reliability
If spring contact arms are used to provide contact force, then initial engagement is reliable, but contact force decreases over time reducing reliability during high vibration
Solution Approach 1:
The patent modifies the spring contact arm geometry by applying bright nickel plating, which reduces friction and wear during sliding contact. This parameter change maintains the spring's contact force over time, ensuring reliable engagement even during high vibration conditions throughout the service life.
3Reliability
If stainless steel conductive surfaces are used, then initial contact resistance is low, but oxidation over time increases contact resistance sufficiently to cause signaling problems
Solution Approach 1:
The patent applies bright nickel plating to the stainless steel conductive surfaces, fundamentally changing the surface chemical properties. This coating prevents oxidation of the stainless steel, maintaining stable low contact resistance and reliable signal transmission throughout the component's service life.
Solution Approach 2:
The patent creates a composite surface structure with stainless steel substrate providing mechanical strength and bright nickel coating providing oxidation resistance. This composite material approach ensures stable electrical contact resistance and reliable signaling over extended periods.
4Reliability
If conventional switch assemblies are used, then basic switching function is achieved, but contact resistance increases over time due to oxidation of wear particles
Solution Approach 1:
The patent applies bright nickel plating to the contact surfaces, changing the material properties to be more resistant to oxidation. This prevents the formation of oxidized wear particles that would otherwise increase contact resistance and degrade switching reliability over time.
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
The solution extends the life expectancy of the switch system, reduces contact resistance, requires less force to move the actuator, and improves functionality during severe vibrations, ensuring reliable signal transmission.
Implementation Method 1
The tracks are formed by a lead frame having parallel extending strips insert molded in electrically insulating plastic and exposed at selected locations along each track to provide a unique binary electrical input indicative of the particular location of an actuator.
Implementation Method 2
The actuator comprises a plurality of leaf springs with a pair of respective leaf springs aligned with each track.
Implementation Method 3
Since the spring contact arms and the stationary conductive segments are stainless steel, exposure to oxygen, time and heat cause them to oxidize and the subsequent oxidized wear particles also causing the contact resistance to increase
Data Source
AI summary
A linear vehicle transmission switch (10) has first and second interfitting housing members (12, 14) each having an electrically conductive lead frame (12m) insert molded in electrically insulative material and formed with exposed segments (12f) of lead frame material along linear tracks. An elongated actuator (16) is slidably received in a channel of one of the housing members and is disposed along a side of the tracks. A paddle (16b) extends transversely across the tracks. Ribs are disposed between tracks and dimensioned to limit rotational movement of the paddle. A pair of stabilized contact switches is disposed on the paddle for each track. The housing members have a selected camber to lower the force required to move the actuator. The lead frames are plated to reduce contact resistance and improve wear.