Hybrid Transmission Torque Modulation via Electric Machine

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Solution Overview

Problem

Conventional vehicles experience driveline disturbances during gear shifts due to inertial torque changes, leading to poor shift quality, and existing input torque modulation methods face limitations such as limited engine torque reduction authority and delayed response, affecting fuel efficiency and emissions.

Innovation Solution

A method for controlling transmission input torque in hybrid electric vehicles by using an electric machine to modulate torque during gear shifts, allowing concurrent operation of the engine and electric machine to reduce output shaft torque disturbances, with the electric machine operating as a motor or generator to supplement or reduce engine torque as needed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If conventional input torque modulation is used during gear shifts, then engine torque reduction is achieved, but the response is delayed and torque reduction authority is limited

Engineering Contradiction:

Improvetorque modulation response speedVSAvoidtorque modulation authority

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent combines the engine and electric machine into a unified torque control system where both power sources work together to achieve torque modulation. The controller coordinates engine torque and electric machine torque to meet the desired net torque target, leveraging the rapid response of the electric machine while maintaining overall system reliability through dual-power-source redundancy and coordination.

Inventive Principle:

Principle #5Merging (Combining)

2Force

If spark retardation is used for torque modulation, then torque reduction is achieved, but fuel efficiency deteriorates

Engineering Contradiction:

Improvetorque modulation capabilityVSAvoidfuel efficiency

Core Design Contradiction:

ForceVSUse of energy by moving object

Solution Approach 1:

The patent replaces the conventional mechanical/combustion-based torque modulation (spark retardation) with an electrically-based torque modulation system. The electric machine provides torque modulation through electrical control, which does not incur the fuel efficiency penalty associated with spark retardation, as it can operate independently of the combustion process timing.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Force

If engine deceleration is increased during upshift, then inertial torque is offset, but output shaft torque disturbance increases

Engineering Contradiction:

Improveinertial torque offsetVSAvoidoutput shaft torque disturbance

Core Design Contradiction:

ForceVSObject-affected harmful factors

Solution Approach 1:

The patent implements a feedback control system that continuously monitors the actual net torque transmitted to the transmission input and compares it to the desired net torque target. The controller adjusts engine torque and electric machine torque based on this feedback to minimize the error, thereby offsetting inertial torque while simultaneously minimizing output shaft torque disturbance through closed-loop control.

Inventive Principle:

Principle #23Feedback

4Speed

If downshift speed is increased, then shift responsiveness is improved, but output torque spike and drop increase

Engineering Contradiction:

Improvedownshift speedVSAvoidoutput torque spike and drop

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by proactively modulating engine and electric machine torque before and during the downshift event. The controller predicts the torque disturbances that will occur during rapid downshift and applies compensating torque modulation in advance and during the shift, thereby enabling fast downshifts while minimizing the harmful torque spikes and drops that would otherwise occur.

Inventive Principle:

Principle #10Preliminary action

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 approach reduces output shaft torque disturbances and improves shift quality by leveraging the responsiveness of the electric machine, enabling accurate torque modulation and minimizing spikes or drops during upshifts and downshifts, thus enhancing the overall driving experience.

Implementation Method 1

an electric machine able to function alternately as a motor and a generator... during the ratio change phase of the downshift, operating the electric machine as a motor

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Implementation Method 2

an electric machine able to function alternately as a motor and a generator

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Data Source

PatentUS9056610B2Transmission downshift input torque modulation for a hybrid electric vehicle

Publication Date: 2015.06.16 FORD GLOBAL TECH LLC

AI summary

In a powertrain for motor vehicle that includes an engine, an electric machine able to function alternately as a motor and a generator, and a transmission whose input is driveably connected to the engine and the electric machine, a method for controlling transmission input torque during an downshift including using the engine to produce torque transmitted to the transmission input, during the ratio change phase of the downshift, operating the electric machine as a motor, and controlling a net torque transmitted to the transmission input by using the engine to drive the transmission and the electric machine concurrently, and during the torque transfer phase of the downshift, operating the electric machine as a generator.