Electric Machine Traction Control for Work Vehicle Slip

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Solution Overview

Problem

Existing work vehicle traction control systems experience wear and increased operating costs due to repeated usage of brake or clutch components, which are necessary to limit power to ground engaging elements during slip conditions.

Innovation Solution

A traction control unit that uses an electric infinitely variable transmission (eIVT) with an electric machine to selectively reduce the speed or torque output when a slip condition is identified, rather than relying on brakes or clutches, by comparing commanded and actual ground speeds and adjusting the electric machine's output accordingly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If brake or clutch components are used to limit power to ground engaging elements during slip conditions, then traction control is achieved, but mechanical wear increases and operating costs increase

Engineering Contradiction:

Improvetraction controlVSAvoidmechanical wear

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The patent replaces the mechanical brake/clutch system with an electric machine (motor-generator) that can rapidly adjust power delivery to the ground engaging elements. The electric machine converts mechanical energy to electrical energy and back, providing slip control without direct mechanical contact, thereby eliminating wear on brake pads and clutch discs while maintaining effective traction control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the control parameter from mechanical force application (brakes/clutches) to electrical power modulation. By controlling the electrical parameters of the motor-generator (voltage, current, frequency), the system can precisely regulate power delivery to match actual ground conditions, reducing slip without the wear associated with mechanical friction devices.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If brake or clutch components are repeatedly actuated during slip conditions, then traction control is maintained, but operating costs increase

Engineering Contradiction:

Improvetraction controlVSAvoidoperating costs

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The electric machine replaces repeated mechanical actuation of brakes and clutches with electrical control. The motor-generator can rapidly adjust power delivery through electrical parameter changes without mechanical wear, reducing maintenance costs and energy loss associated with repeated friction-based slip control operations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Loss of substance

If electric machine output is reduced to control slip, then mechanical wear is reduced, but power delivery to output shaft is limited

Engineering Contradiction:

Improvemechanical wearVSAvoidpower delivery

Core Design Contradiction:

Loss of substanceVSPower

Solution Approach 1:

The electric machine provides dynamic power delivery adjustment based on real-time slip detection. When slip is detected, the system temporarily reduces power through electrical control rather than mechanical restriction. Once slip is corrected, full power delivery is restored, maintaining high power capability while avoiding the permanent power loss associated with mechanical slip control devices.

Inventive Principle:

Principle #15Dynamics

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 reduces mechanical wear in the transmission assembly and lowers operating costs by addressing slip conditions without actuating clutches, thereby improving traction control performance and longevity.

Implementation Method 1

An electric machine is operably connected to the engine and to the variator, with the electric machine providing rotational power to the variator

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a transmission assembly having a variator selectively connected to the engine... transferring rotational power from the electric machine to the variator

Methodology Applied

Scientific EffectMechanical energy transformation:

Data Source

PatentUS20230235535A1System and method for traction control in a work vehicle with an electric infinitely variable transmission

Publication Date: 2023.07.27 DEERE & CO

AI summary

A work vehicle includes an engine and a transmission assembly having a variator, a gear arrangement, and an electric machine operably connected to the engine and to the variator to provide rotational power to the variator. The transmission assembly selectively transfers power from one or both of the engine and the electric machine to an output shaft to drive ground engaging elements of the work vehicle. A traction control unit controls a speed or torque output of the electric machine to provide traction control for the work vehicle, with the traction control unit operating to receive inputs on a commanded ground speed and an actual ground speed of the work vehicle, compare the commanded ground speed to the actual ground speed and, when the commanded ground speed exceeds the actual ground speed by a threshold amount, reduce the speed or torque output of the electric machine, thereby providing traction control for the ground engaging elements.