Vehicle Power Transfer Unit Shift Collar Mechanism

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Solution Overview

Problem

Existing power transfer units in vehicles lack efficient mechanisms for selectively distributing torque among driveline components, particularly in four-wheel and all-wheel configurations, leading to limitations in torque control and durability.

Innovation Solution

A vehicle power transfer unit assembly that includes an input shaft, intermediate shaft, central shaft, peripheral shaft, proximal shift collar, and distal shift collar, with shift forks and springs to selectively engage and disengage splines for torque transfer between these components, allowing for multiple torque distribution positions via a spline engagement mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple separate motor-actuators are used to operate shift collars, then torque distribution control is achieved, but device complexity increases

Engineering Contradiction:

Improvetorque distribution controlVSAvoidnumber of actuators

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines multiple shift collar actuation functions into a single motor-actuator that operates both the proximal and distal shift collars through a shared drive shaft and gear mechanism, reducing the number of actuators from two to one while maintaining torque distribution control capability

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single motor-actuator is designed with universal functionality to control multiple shift collars at different positions along the input shaft, allowing one actuator to perform the work of multiple actuators through mechanical transmission elements

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Productivity

If shift collars are positioned far from the input shaft, then torque transfer efficiency improves, but shift fork operation becomes difficult

Engineering Contradiction:

Improvetorque transfer efficiencyVSAvoidshift fork operation

Core Design Contradiction:

ProductivityVSEase of operation

Solution Approach 1:

The patent positions shift collars at multiple locations along the input shaft's length (axial dimension) rather than at a single radial position, enabling both efficient torque transfer and accessible shift fork operation by distributing shift points along the shaft's longitudinal axis

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent introduces a drive shaft as an intermediary mechanical element that transmits actuation force from the motor-actuator to the shift collars positioned at optimal locations for torque transfer, mediating between the actuator and the shift collar engagement points

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11691506B2Shifting mechanism for a vehicle power transfer unit

Publication Date: 2023.07.04 GKN AUTOMOTIVE LTD

AI summary

A vehicle power transfer unit assembly comprises an input shaft, an intermediate shaft at least partially surrounding the input shaft, a central shaft adjacent the input shaft, a peripheral shaft at least partially surrounding the central shaft, a first shift collar, and a second shift collar. The first shift collar is operable between a first position where torque is transferred from the input shaft to the intermediate shaft and a second position where torque is not transferred from the input shaft to the intermediate shaft. The second shift collar is operable between a third position where torque is transferred from the input shaft to the peripheral shaft and a fourth position where torque is transferred from the input shaft to the central shaft.