Transfer Case Locking Sleeve for Positive Torque Coupling

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Solution Overview

Problem

Current transfer cases lack a mechanism for positively coupling the primary and secondary output shafts to efficiently transfer torque between them, especially in four-wheel drive modes, relying on friction couplings which may not provide a stable connection.

Innovation Solution

Incorporating a secondary torque transfer mechanism with a locking sleeve and actuator that selectively couples the primary and secondary output shafts via a sprocket and chain, allowing for a positive torque transfer between the shafts, enabling a stable and efficient torque transfer in four-wheel drive operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a friction coupling mechanism is used to transfer torque between primary and secondary output shafts, then the device complexity is reduced, but the reliability of torque transfer deteriorates due to unstable connection

Engineering Contradiction:

Improvestructure complexityVSAvoidtorque transfer stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The torque transfer mechanism is segmented into multiple functional components: a locking sleeve with first and second splined connections, a plate clutch for friction coupling, and a chain-sprocket system. This segmentation allows each component to perform a specific function (positive locking vs. friction-based torque transfer) while maintaining overall system manageability and reliability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The locking sleeve acts as an intermediary component between the primary output shaft and the secondary output shaft (via the sprocket). It provides a positive mechanical connection through splined engagements, mediating the torque transfer in a reliable manner without requiring direct friction coupling between the shafts

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a locking mechanism with splined connections is added to positively couple the primary and secondary output shafts, then the reliability of torque transfer is improved, but the device complexity increases

Engineering Contradiction:

Improvetorque transfer stabilityVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The locking sleeve serves multiple functions: it provides a positive mechanical connection through the first splined connection with the primary output shaft, engages with the second splined connection with the sprocket for torque transfer, and can be actuated by the actuator mechanism. This multi-functionality reduces the need for separate components for each function

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The actuator mechanism is nested within the transfer case housing, and the locking sleeve is positioned within the torque transfer mechanism. The components are arranged in a compact nested configuration where the actuator moves the locking sleeve axially to engage or disengage the splined connections, optimizing space utilization

Inventive Principle:

Principle #7Nested doll (Nesting)

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 provides a stable and efficient torque transfer between the primary and secondary output shafts, enhancing the vehicle's four-wheel drive capability by ensuring consistent power distribution without relying solely on friction couplings.

Implementation Method 1

a plate clutch coupled to the sprocket to selectively form a friction coupling with the primary output shaft

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

the locking sleeve forms a first splined connection with the primary output shaft and forms a second splined connection with the sprocket to transfer torque

Methodology Applied

Scientific EffectMechanical coupling via splines: Mechanical Force

Data Source

PatentUS10183577B2Transfer case with four wheel lock

Publication Date: 2019.01.22 BORGWARNER INC

AI summary

A transfer case includes primary and secondary output shafts, along with a secondary torque transfer mechanism and a locking mechanism, which are configured to selectively couple the primary and secondary output shafts. The secondary torque transfer mechanism comprises a sprocket coupled to the secondary output shaft, and a plate clutch coupled to the sprocket to selectively form a friction coupling with the primary output shaft. The locking mechanism selectively couples the primary output shaft to the sprocket, and includes a locking sleeve and an actuator that moves the locking sleeve between a first position and a second position. In the first position, the locking sleeve forms a first splined connection with the primary output shaft and forms a second splined connection with the sprocket. In the second position, the locking sleeve forms the first splined connection with the primary output shaft and forms a second splined connection with the sprocket.