Transfer Case Actuator Cam Follower Mechanism for Blocked Shift Resolution
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Solution Overview
Problem
Existing transfer case systems face issues with blocked shift events due to tooth-on-tooth contact, which prevents the fork from engaging properly, leading to operational inefficiencies and potential damage.
Innovation Solution
A transfer case design incorporating a motor and cam assembly with a resilient rotary coupling, including a cam structure with interconnected track portions and face cam portions, along with fork shafts and sensors, allows for compliant rotation and translation of forks, enabling the system to overcome blocked shift events by generating sensor signals for mode and range detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid cam mechanism is used to translate the fork, then the shifting action is precise and controlled, but the system cannot accommodate blocked shift events where teeth abut and fail to engage
Solution Approach 1:
The patent changes the mechanical parameter of the coupling between motor and cam from rigid to resilient. The torsion spring allows angular deflection between the motor output shaft and cam, enabling the system to accommodate blocked shift events by absorbing mechanical interference through elastic deformation while maintaining controlled fork translation during normal operation
Solution Approach 2:
The torsion spring provides beforehand cushioning by being pre-installed in the cam mechanism to absorb potential mechanical shocks from blocked shift events. This resilient element is positioned in advance to protect the system from damage when teeth abut and fail to engage, allowing the motor to continue rotating without transmitting damaging forces to the fork mechanism
2Measurement precision
If sensors are added to detect fork positions, then the system can detect range and mode positions, but the device complexity increases
Solution Approach 1:
The patent replaces complex mechanical position indication systems with electronic sensors that detect fork positions optically or magnetically. Instead of using mechanical linkages or visual indicators, the system uses sensors to detect the presence or position of targets attached to the fork, converting mechanical position information into electrical signals for the control system
Solution Approach 2:
The fork structure itself incorporates or carries the sensor targets, making the moving component serve dual purposes: both actuating the transmission elements and providing the detection target for position sensing. This eliminates the need for separate indicator mechanisms, as the fork's own structure enables its position to be detected
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 design ensures smooth operation by allowing the transfer case to transition between modes and ranges despite tooth-on-tooth contact, preventing damage and maintaining efficiency.
Implementation Method 1
The resilient rotary coupling permits compliant rotation between a motor output shaft and a cam structure
Implementation Method 2
rotation of the cam structure about the cam axis causes corresponding translation of the fork along the actuation axis
Data Source
AI summary
A transfer case with an actuator for operating a two-speed transmission (i.e., range mechanism) and a clutch (i.e., mode mechanism). The actuator employs a motor-driven cam structure that coordinates the movement of a first fork, which is associated with the range mechanism, and a second fork that is associated with the mode mechanism. A resilient coupling is employed to provide compliance between the motor and the cam structure in the event that tooth-on-tooth contact inhibits the range mechanism from changing from a high-range mode and a low range mode. Compliance is provided between the cam structure and the second fork in the event that tooth-on-tooth contact inhibits the mode mechanism from changing from a 2WD mode to a 4WD mode. A sensor system identifies the placement of the first and second forks in various positions and responsively generates associated sensor signals.