Vehicle Driveline Disconnect Actuator with Cam-Driven Rotary Coupling
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Solution Overview
Problem
Existing all-wheel drive driveline systems with disconnect mechanisms lack an efficient actuation system that effectively manages the disconnection and reconnection of driveline components, leading to suboptimal power transmission and efficiency.
Innovation Solution
A vehicle driveline component featuring an actuator with a rotary coupling system, comprising a motor, transmission, first and second cams, and biasing springs, which allows for the decoupling and recoupling of driveline components through a dog clutch mechanism, enabling efficient power transmission and disconnection by rotating the cams to align cam features and biasing springs to control the position of the coupling members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a disconnect mechanism is implemented in a power take-off unit, then power transmission efficiency is improved by allowing selective disconnection of the secondary axle, but the device complexity increases due to the additional actuation system components (cams, coupling members, biasing springs)
Solution Approach 1:
The actuation system merges multiple functions into integrated components. The first and second cams work together with coupling members to simultaneously control engagement and disengagement of the driveline disconnect mechanism, reducing the need for separate actuation components and simplifying the overall system while maintaining power transmission efficiency
Solution Approach 2:
The mechanism employs dynamic elements including rotatable cams that can pivot between engagement and disengagement positions, and coupling members that can move axially and radially. This dynamic design allows the system to transition smoothly between connected and disconnected states, optimizing power transmission while avoiding the need for complex fixed-position control systems
2Ease of operation
If cam features are aligned to extend or retract the second cam, then precise control over coupling position is achieved, but the manufacturing precision requirements increase for cam feature alignment
Solution Approach 1:
The cam features are designed with symmetric geometric relationships where corresponding features on the first and second cams are positioned at equivalent radial distances and angular intervals. This equipotential design ensures that when cam features align, the coupling members naturally reach their intended positions without requiring ultra-precise manufacturing tolerances, as the geometry itself provides the positioning reference
Solution Approach 2:
The cam features are pre-configured in specific angular and radial positions during manufacturing to automatically guide the coupling members to the correct engagement and disengagement positions. This preliminary positioning of cam features allows the mechanism to self-align during operation, reducing the need for high-precision real-time control and simplifying both manufacturing and operation
3Reliability
If biasing springs are used to control cam and coupling member positions, then reliability of engagement is improved, but the device complexity increases due to additional spring components
Solution Approach 1:
The biasing springs are integrated into the cam and coupling member assembly to automatically maintain engagement forces without requiring external control systems. The springs self-adjust to maintain optimal contact between cam features and coupling members throughout the operational cycle, ensuring reliable engagement while using minimal components. Each spring serves multiple functions including maintaining force, compensating for wear, and guiding motion
Solution Approach 2:
The biasing springs provide counteracting forces that balance the loads on the coupling members during engagement and disengagement. By positioning springs to oppose the direction of separation forces, the system maintains reliable contact between mating surfaces without requiring excessive spring strength or additional stabilization components, thus improving reliability while limiting complexity
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 enhances the efficiency and reliability of driveline disconnection and reconnection, improving power transmission by allowing precise control over the coupling and decoupling of driveline components, thereby optimizing power distribution between axles.
Implementation Method 1
The first biasing spring is disposed between the first and second cams and biases the second cam toward the retracted position
Implementation Method 2
The second biasing spring is disposed between the first coupling member and the second cam
Data Source
AI summary
A vehicle driveline component with an actuator and a rotary coupling. The actuator has an actuator housing, a motor, a transmission, a first cam, a second cam, and a first biasing spring. The motor is coupled to the actuator housing and includes a motor output member. The transmission has a transmission input member, which is driven by the motor output member, and a transmission output member. The first cam is housed in the actuator housing and is coupled to the transmission output member for rotation therewith. The first cam has a first set of cam features that are disposed about a first annular surface. The second cam has a cam body, which is received in the first cam, and a second set of cam features that are disposed about a second annular surface. The second set of cam features abut the first set of cam features. Rotation of the first cam relative to the second cam into a first position orients the first set of cam features onto the second set of cam features so as to position the second cam in an extended position relative to the first cam. Rotation of the first cam relative to the second cam into a second position orients the first set of cam features onto the second set of cam features so as to position the second cam in a retracted position relative to the first cam. The first biasing spring is disposed between the first and second cams and biases the second cam toward the retracted position. The rotary coupling has a first coupling member, a second coupling member and a second biasing spring. The first coupling member is rotatably and axially slidably received in the second cam. The first coupling member is axially movable between a first coupling position, in which the first coupling member is decoupled from the second coupling member, and a second coupling position in which the first coupling member is coupled to the second coupling member to permit the transmission of rotary power through the rotary coupling. The second biasing spring is disposed between the first coupling member and the second cam.