Hybrid Driveline Downshift Torque Disturbance Control

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Solution Overview

Problem

Hybrid vehicles experience driveline torque disturbances during transmission downshifting in regeneration mode due to inadequate torque transfer by transmission clutches, especially in drivelines with a driveline disconnect clutch, which increases inertia and affects the smoothness of gear shifting.

Innovation Solution

Adjusting motor torque in response to the percentage of transmission gear shift completion using a closed-loop control system, leveraging the higher torque bandwidth of an electric machine to manipulate torque transmitted via the gear clutch and reduce driveline torque disturbances during downshifts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If transmission clutches are used for torque transfer during downshift, then gear shifting is enabled, but driveline torque disturbances occur due to insufficient torque transfer capability

Engineering Contradiction:

Improvegear shifting speedVSAvoiddriveline torque disturbance

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent combines the torque transfer function with the electric machine (motor/generator) that is already present in the hybrid drivetrain. During regeneration mode downshifts, the electric machine provides additional torque to supplement the transmission clutch, enabling smooth torque transfer without disturbances. This merging of functions allows the electric machine to act as a torque buffer that compensates for clutch limitations.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The electric machine serves as an intermediary element between the engine and transmission during downshift operations. It mediates the torque transfer process by absorbing excess torque during clutch engagement and releasing it controllably, thereby preventing torque disturbances from propagating through the driveline to the wheels.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of energy

If a driveline disconnect clutch is included to improve fuel economy, then fuel efficiency increases, but driveline inertia increases and exacerbates torque disturbances during shifting

Engineering Contradiction:

Improvefuel economyVSAvoiddriveline inertia

Core Design Contradiction:

Loss of energyVSForce

Solution Approach 1:

The control system continuously monitors driveline conditions during downshift operations and dynamically adjusts electric machine torque based on feedback signals. When torque disturbances are detected or anticipated during clutch engagement, the controller modulates electric machine output in real-time to compensate for inertia effects from the disconnect clutch, maintaining smooth operation despite the added mass.

Inventive Principle:

Principle #23Feedback

3Device complexity

If gear clutch actuator bandwidth is limited, then device complexity is reduced, but ability to shape clutch slippage during downshift is insufficient

Engineering Contradiction:

Improveactuator complexityVSAvoidclutch slippage control capability

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent replaces the need for a high-bandwidth mechanical actuator with an electrically controlled torque source. Instead of requiring the gear clutch actuator to rapidly modulate torque, the electric machine provides precise torque control through electrical current modulation. This substitution transfers the control burden from the mechanical actuator to the electric machine controller, enabling sophisticated slippage shaping without increasing actuator complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS9682699B2Methods and system for downshifting during regeneration

Publication Date: 2017.06.20 FORD GLOBAL TECH LLC

AI summary

Systems and methods for shifting a transmission of a hybrid driveline that includes an electric machine that operates in a regeneration mode are presented. The systems and methods may adjust a feedforward motor torque command via an adaptive parameter in response to an error that is based on percentage of shift complete.