Torque Converter Slip Control Using Motor Torque

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Solution Overview

Problem

In hybrid vehicles, accurately controlling micro slip in the torque converter is challenging due to difficulties in estimating engine torque during transient events, leading to inefficiencies and reduced fuel economy.

Innovation Solution

The use of electrical motor torque for precise control of micro slip in the torque converter, combined with feed forward and feedback control algorithms, allows for accurate adjustment of torque converter clutch pressure, independent of engine torque estimation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If feed forward control is used to predict system operation based on engine torque estimation, then micro slip control can be implemented, but the inaccurate engine torque estimation during transient events leads to poor control accuracy

Engineering Contradiction:

Improvemicro slip controlVSAvoidengine torque estimation accuracy

Core Design Contradiction:

Extent of automationVSMeasurement precision

Solution Approach 1:

The patent introduces motor torque as an intermediary measurement to replace direct engine torque estimation. The motor torque sensor provides accurate real-time data that mediates the control system's ability to predict and control micro slip during transient events, bypassing the unreliable engine torque estimation problem.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical engine torque estimation system with an electrical measurement system (motor torque sensing). This substitution allows for precise digital measurement of torque conditions without relying on mechanical sensors or complex estimation algorithms that fail during transient events.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If feedback control is used to monitor slip, then closed loop control can be achieved, but the timing delay in the feedback circuit prevents accurate control during transient events

Engineering Contradiction:

Improveclosed loop controlVSAvoidfeedback circuit delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by using feed forward control based on accurate motor torque measurements to predict and prepare the optimal bypass clutch pressure before the transient event fully develops. This anticipatory control compensates for the inherent feedback delay, ensuring accurate micro slip control during rapid transient conditions.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If engine torque is used for torque converter control, then control can be implemented, but the difficulty in accurately estimating engine torque during transient events reduces control quality

Engineering Contradiction:

Improvetorque converter controlVSAvoidtorque measurement accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent uses motor torque as an intermediary measurement that accurately reflects the torque conditions in the torque converter during transient events. This intermediary measurement provides the control system with reliable data without requiring direct measurement or estimation of engine torque, thereby maintaining ease of operation while improving measurement precision.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS8715136B1Torque converter slip control based on motor torque during transient events

Publication Date: 2014.05.06 FORD GLOBAL TECH LLC

AI summary

A hybrid vehicle with an engine, an electric drive motor and battery, an automatic transmission with a torque converter having a bypass clutch, and a powertrain controller dynamically adjust the torque converter slip to balance fuel economy and drivability during a transient torque request by using motor torque to satisfy the transient torque and applying feed forward control of the fluid pressure in the bypass clutch based on the motor torque and feedback control of the slip to maintain torque converter torque ratio substantially constant during the transient event.