Engine Torque Control for Wheel Shaft Disconnect Transitions

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Solution Overview

Problem

Conventional engine torque control systems in series hybrid powertrains experience delays in torque increase during drive shaft disconnect system transitions due to waiting for the system to close, especially under low state of charge conditions, leading to suboptimal performance and potential safety issues.

Innovation Solution

An engine torque control system that determines an optimum engine torque command by calculating minimum and maximum constraints based on drive shaft disconnect system states, using a control system to manage engine torque during transitions, ensuring quick torque fulfillment during disconnect system closing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the conventional control system waits to increase engine torque until the drive shaft disconnect system is closed, then the system ensures proper mechanical connection before torque transfer, but this results in a delay in torque delivery that degrades performance and may compromise safety

Engineering Contradiction:

Improveproper torque transferVSAvoidtorque delivery delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The control system performs preliminary torque buildup by increasing engine torque gradually during the transition phase before the drive shaft disconnect system is fully closed. This preliminary action ensures that when the system closes, the torque is already near the requested level, minimizing delivery delay while maintaining reliability through controlled incremental increases.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts engine torque based on the real-time state of the drive shaft disconnect system. Rather than using a static wait-then-apply approach, the control system continuously monitors disconnect system position and modulates torque accordingly, enabling smooth transition from disconnected to connected state while optimizing torque delivery timing.

Inventive Principle:

Principle #15Dynamics

2Speed

If the engine torque is increased during the open state of the drive shaft disconnect system, then the torque response time is improved, but this may cause mechanical stress or damage to the disconnect system components

Engineering Contradiction:

Improvetorque response timeVSAvoidmechanical stress on disconnect system

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The control system applies preliminary anti-action by implementing torque constraints that prevent excessive torque application during the open state of the drive shaft disconnect system. Before the disconnect system is fully closed, the system limits maximum torque to levels that avoid damaging the disconnect mechanism, while still allowing sufficient torque buildup to improve response time.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The system changes torque parameters dynamically based on the disconnect system state. During the open state, torque is limited to a maximum constraint value; during the closing transition, torque gradually increases; and after closure, full torque is applied. This parameter adaptation resolves the contradiction by adjusting torque levels to match system readiness.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the engine torque is constrained during transition to ensure component safety, then mechanical reliability is maintained, but the overall torque delivery performance and driver demand fulfillment are degraded

Engineering Contradiction:

Improvecomponent safetyVSAvoidtorque delivery performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The control system maintains continuity of useful action by ensuring torque delivery is continuous and smooth throughout the transition. Rather than abruptly applying or limiting torque, the system continuously adjusts torque levels to balance component protection with performance requirements, keeping the torque delivery process uninterrupted and effective.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The system uses feedback from the drive shaft disconnect system position and torque sensor data to continuously adjust engine torque commands. This closed-loop control ensures that torque constraints are applied appropriately to protect components while maximizing torque delivery performance within safe operating boundaries.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS12472934B1Engine torque control during wheel shaft disconnect transitions on series hybrid powertrains

Publication Date: 2025.11.18 FCA US LLC

AI summary

An engine torque control method for an electrified vehicle having a series hybrid powertrain with at least two electric traction motors includes, in response to detecting an open-to-closed state transition of a drive shaft disconnect system configured to selectively connect and disconnect a first axle system or a pair of first wheels of the electrified vehicle from a first electric traction motor of the series hybrid powertrain, determining an optimum engine torque for the open-to-closed state transition based on a set of parameters for the open state of the drive shaft disconnect system, determining engine torque constraints for the open state and the closed state of the drive shaft disconnect system, applying the engine torque constraints to the optimum engine torque for the open-to-closed state transition to obtain a final engine torque command, and controlling an engine of the series hybrid powertrain based on the final engine torque command.