Manual Transmission Reverse Lockout Shifter Assembly
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Solution Overview
Problem
Drivers may inadvertently shift manual transmission vehicles into reverse gear while traveling forward, potentially damaging the transmission and drivetrain components.
Innovation Solution
A shifter assembly with a reverse lockout mechanism that requires affirmative action from the driver to engage the reverse gear position, utilizing a system of cables and a coupling mechanism to prevent unintended shifting into reverse gear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reverse lockout mechanism is implemented to prevent inadvertent shifting, then transmission reliability is improved, but device complexity increases due to additional cables and coupling mechanisms
Solution Approach 1:
The patent implements a nested cable system where a first cable is positioned within a second cable, both extending through the shift lever. The coupling mechanism integrates multiple components (first member, second member, third member) that nest together to control the lockout function. This nesting approach consolidates multiple control functions into a compact arrangement, reducing overall spatial complexity while maintaining the reliability benefits of the lockout mechanism.
Solution Approach 2:
The shift lever serves multiple functions: it directly controls gear selection for forward gears, houses the reverse lockout mechanism, and contains bore passages that guide both cables. The coupling mechanism integrates the lockout control function with the existing shift lever structure, allowing a single component to perform both shifting and lockout control duties. This multi-functionality reduces the need for separate dedicated components, thereby managing device complexity.
2Reliability
If a complex cable and coupling system is used for reverse lockout, then shifting protection is improved, but ease of operation deteriorates due to additional components the driver must manipulate
Solution Approach 1:
The patent merges the reverse lockout control function with the existing shift lever operation. The first and second cables are both routed through the shift lever, and the coupling mechanism integrates these cable controls with the shift lever's movement. This consolidation allows the driver to access the lockout function through the familiar shift lever interface rather than requiring a separate control mechanism, thereby maintaining ease of operation while achieving shifting protection.
Solution Approach 2:
The coupling mechanism acts as an intermediary between the driver's manipulation of the shift lever and the engagement of the reverse lockout. The first member, second member, and third member of the coupling translate the driver's input movements into the appropriate cable tension changes that engage or disengage the lockout. This intermediary mechanism smooths the interaction between the driver and the complex cable system, making the operation intuitive despite the underlying complexity.
3Ease of operation
If the shift lever is made longer to improve ergonomics, then ease of operation improves, but the space required in the vehicle interior increases
Solution Approach 1:
The patent employs a nested cable arrangement where the first cable is positioned within the second cable, and both are routed through passages in the shift lever. This nesting allows the cable system to be compact while the shift lever maintains its full length for ergonomic operation. The nested structure efficiently uses the internal volume of the shift lever, avoiding the need for additional external space that would be required if the cables were routed separately.
Data Source
AI summary
A shifter assembly may include a shift lever, an actuation member, a coupling, a first cable and a second cable. The shift lever may be connected to a housing for pivotable motion relative to the housing. The actuation member may be connected to the shift lever and may be movable relative thereto between a first position and a second position. The coupling may be connected to the shift lever and may include first and second members slidably engaging each other. The first cable may have a first end connected to the second member and a second end that can be coupled to a reverse lockout mechanism. The second cable may be connected to the actuation member and the second member of the coupling such that movement of the actuation member relative to the shift lever causes corresponding motion of the second member relative to the shift lever.