Brake-Transmission Shift Interlock Decoupled Linkage
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Solution Overview
Problem
Current brake-transmission shift interlocks (BTSI) are sensitive to side loading due to coupled inhibitor and solenoid armature designs, which can lead to solenoid damage, and often require increased travel for proper function, making them inefficient and prone to failure under high shear loads.
Innovation Solution
A decoupled inhibitor-solenoid armature linkage system that allows independent movement of the inhibitor, preventing side loads from being transmitted to the solenoid armature, and a decoupled park position switch that operates independently of the solenoid armature, enabling separate optimization and reducing reliance on precise tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a coupled inhibitor-solenoid armature design is used, then the structure is simpler, but the solenoid becomes sensitive to side loading and prone to damage
Solution Approach 1:
The inhibitor is separated from the solenoid armature into independent components. The inhibitor is now a separate element that can move independently along the armature's path without being mechanically coupled to it, eliminating the transmission of side loads to the solenoid.
Solution Approach 2:
A guide structure acts as an intermediary between the inhibitor and the solenoid armature. The guide constrains the inhibitor's movement to a linear path parallel to the armature's motion, preventing lateral forces from being transmitted to the armature while still allowing the inhibitor to perform its blocking function.
2Device complexity
If a coupled inhibitor-solenoid armature design is used, then fewer components are needed, but the device requires increased travel to accommodate dimensional stackups
Solution Approach 1:
By separating the inhibitor from the armature, each component can be optimized independently for compactness. The inhibitor can be positioned closer to the solenoid body without requiring excessive travel distance, as it moves in its own constrained path rather than being coupled to the armature's full stroke.
3Volume of stationary object
If a coupled park position switch and BTSI solenoid design is used, then the assembly is more compact, but the switch requires more travel and relies on precise tolerances
Solution Approach 1:
The park position switch is decoupled from the BTSI solenoid armature mechanism. The switch now responds to a different motion - specifically, the movement of the shifter lever or a separate indicator - rather than relying on the axial motion of the solenoid armature. This allows the switch and solenoid to be positioned closer together without requiring excessive travel or tight tolerances between components.
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 decoupled system enhances solenoid durability by preventing side loading damage and allows for independent optimization of the inhibitor and switch, resulting in improved reliability, reduced manufacturing costs, and smaller package sizes while maintaining noise dampening effectiveness.
Implementation Method 1
The solenoid has an armature which is normally extended as by the biasing force of a spring, and which is retracted from its normal (unpowered) position when activated in response to a signal indicating that moving the shifter from the park position is permissible.
Data Source
AI summary
A sub-assembly for a brake transmission shift interlock system. The sub-assembly includes an inhibitor for preventing shifting of a vehicle transmission from a park position in the absence of application of a brake by a vehicle occupant, and a solenoid having a movable armature. A linkage couples the inhibitor to the armature such that movement of the armature produces a movement of the inhibitor. The linkage also couples the inhibitor to the armature so as to permit movement of at least a portion of the inhibitor independent of the armature. A brake transmission shift interlock assembly and a switch assembly incorporating the sub-assembly are also provided.