Transfer Case Actuator Cam Follower Mechanism
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Solution Overview
Problem
Transfer cases with multi-speed transmissions and clutches often require multiple compliance and biasing springs, increasing cost and complexity, while the rotational position of the output shaft cannot accurately determine the operating condition of the transmission or clutch.
Innovation Solution
A transfer case actuator featuring a motor and cam assembly with a resilient rotary coupling, fork shaft, and sensor configuration that uses fewer springs for biasing and compliance, allowing precise determination of movable elements' positions through a sensor system that generates signals based on cam positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple compliance springs and biasing springs are integrated into the actuator assembly, then the transfer case can handle blocked shift events and maintain proper positioning, but the cost and design complexity increase
Solution Approach 1:
The patent removes the complex spring system (multiple compliance springs and biasing springs) from the actuator assembly and replaces it with a simplified mechanism using a motor, cam structure, and resilient rotary coupling. This extraction eliminates unnecessary components while maintaining the ability to handle blocked shift events through the resilient coupling's inherent compliance.
Solution Approach 2:
The patent replaces the mechanical spring-based compliance and positioning system with an electromechanical system consisting of a motor and cam structure. The motor provides controlled actuation, the cam structure translates rotational motion to linear fork movement, and the resilient rotary coupling provides the necessary compliance without requiring multiple springs.
2Measurement precision
If traditional sensor configurations are used, then the sensor can detect fork positions, but the rotational position of the output shaft cannot determine the operating condition of the multi-speed transmission or clutch
Solution Approach 1:
The patent implements a feedback mechanism where the sensor detects the position of the cam structure (which is directly linked to the motor's rotational position), and this information is used to determine the operating conditions of both the multi-speed transmission and clutch. The sensor target with plateaus provides discrete positional feedback that correlates to specific operating states, eliminating the information loss present in traditional configurations.
Solution Approach 2:
The cam structure serves multiple functions: it actuates both the range fork (for multi-speed transmission control) and the mode fork (for clutch control), while the sensor positioned to detect cam structure position can simultaneously determine both operating conditions. This multi-functionality eliminates the need for separate sensing mechanisms for each operating condition.
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 solution reduces the number of springs needed, enhances accuracy in determining the operating conditions of the multi-speed transmission and clutch, and provides reliable operation by using a motor and cam assembly with a sensor system to manage compliance and detect fork positions.
Implementation Method 1
a resilient rotary coupling between the motor and the cam structure. The resilient rotary coupling permits the motor to overcome blocked shift events
Implementation Method 2
The cam structure defines first and second cam tracks... rotation of the cam structure about the cam axis between a first rotary cam position, a second rotary cam position and a third rotary cam position causes corresponding translation of the first 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 or tooth-on-tooth contact inhibits the mode mechanism from changing between a two-wheel drive mode and a four-wheel drive mode. A sensor target and sensor are employed to identify the rotational positioning of the cam structure placement, which is indicative of the modes in which the transmission and the clutch are operating.