Cam Follower Drive Selector with Tactile Feedback
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Solution Overview
Problem
Conventional Forward-Neutral-Reverse drive selector systems for vehicles lack features to maintain gear selection and provide tactile feedback, leading to increased shifting effort and potential misalignment issues with dog-clutch systems.
Innovation Solution
A drive selector system featuring a housing with a cam and follower mechanism, where the cam and follower have protrusions and recesses that resist rotation until a threshold torque is applied, providing tactile feedback and ensuring proper gear engagement through discrete positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pin or dog-clutch system is used to selectively engage the drive axle, then discrete gear positions can be established, but the system requires precise alignment tolerance and may not shift until the engine begins running (dead-head)
Solution Approach 1:
The patent changes the engagement mechanism from a rigid pin/dog-clutch system to a cam-based system with variable geometry. The cam profile is designed to provide gradual engagement rather than abrupt positioning, allowing the follower to ride along the cam surface and naturally find the correct position. This eliminates the need for tight alignment tolerances between the slot and handle while ensuring reliable gear engagement.
2Ease of operation
If a gated shifter slot is used to set allowed positions, then gear position limits are defined, but the system provides no tactile feedback and is aesthetically displeasing
Solution Approach 1:
The cam surface is segmented into distinct engagement zones corresponding to different gear positions (Forward, Neutral, Reverse). Each zone provides a localized tactile sensation when the follower engages with the cam, giving the operator clear feedback about the current gear position without requiring visual confirmation or complex mechanisms.
Solution Approach 2:
The cam-follower interaction creates natural mechanical vibrations and tactile feedback at each engagement point. As the operator moves the shifter lever, the follower encounters the cam surface variations that produce detectable vibrations and resistance changes, providing intuitive tactile feedback about gear selection status.
3Device complexity
If conventional drive selectors are used without features to maintain gear selection, then the system is simple, but shifting effort increases and gear selection may not be maintained
Solution Approach 1:
The cam is pre-configured with engagement zones that automatically maintain gear selection once engaged. The follower rides along the cam surface which is designed to hold the follower in the correct position without requiring additional locking mechanisms or complex maintenance features. The cam geometry itself provides the maintaining function.
Solution Approach 2:
The cam-follower system is self-regulating and self-maintaining. The biasing member keeps the follower in constant contact with the cam surface, and the cam geometry automatically guides the follower to the correct engagement position and maintains it there. The system serves itself by using the inherent mechanics of the cam profile to provide both selection and maintenance functions without additional 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 system effectively retains gear selection, reduces shifting effort, and provides consistent tactile feedback, enhancing the user experience by decoupling force feedback and optimizing shifting effort.
Implementation Method 1
a biasing member, such as a spring, positioned between the cam and the rear wall of the housing and configured to bias the cam toward the follower
Data Source
AI summary
An exemplary drive selector includes a housing, a cam positioned in the housing, a follower coupled to a shaft and in contact with the cam, and a biasing member urging the cam toward the follower. One of the cam and the follower includes at least one protrusion, and the other of the cam and the follower includes a plurality of recesses configured to receive the protrusion. When the protrusion is received in the recess, the force provided by the biasing member resists relative rotation of the cam and the follower.