Hybrid Powertrain Reverse Drive Engine Speed Control

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Solution Overview

Problem

In hybrid electric vehicle powertrains, the reduction in wheel torque during reverse drive due to engine torque interference limits reverse drive performance, especially when the high voltage battery cannot provide sufficient electric power.

Innovation Solution

A calibratable variable engine speed and torque map is used for reverse drive, optimizing engine operation at high speed and low torque to minimize noise and vibration, allowing for a gradual increase in engine speed and power distribution to prioritize reverse drive efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the engine is used to drive the generator to charge the battery during reverse drive, then electric power is generated to meet driver's torque request, but wheel torque is reduced due to engine torque interference

Engineering Contradiction:

Improveelectric powerVSAvoidwheel torque

Core Design Contradiction:

PowerVSForce

Solution Approach 1:

The patent applies parameter changes by using a separate reverse drive map that specifies different engine speed and torque parameters compared to the forward drive map. During reverse drive, the engine operates at high speed and low torque points, which changes the operating parameters to minimize the negative impact on wheel torque while still generating the necessary electric power to meet the driver's torque request.

Inventive Principle:

Principle #35Parameter changes

2Power

If the engine operates at high efficiency operating point, then engine power is maximized, but reverse drive performance is reduced due to torque interference

Engineering Contradiction:

Improveengine powerVSAvoidreverse drive performance

Core Design Contradiction:

PowerVSProductivity

Solution Approach 1:

The patent implements dynamics by using a calibratable variable map that dynamically adjusts engine speed and torque targets based on driving conditions. The reverse drive map allows the engine to operate at high speed and low torque points, dynamically changing the operating strategy from the conventional high efficiency point to optimize reverse drive performance while maintaining necessary power generation.

Inventive Principle:

Principle #15Dynamics

3Object-affected harmful factors

If engine speed is increased gradually from idle to target speed, then noise and vibration are reduced, but time to reach operating point is increased

Engineering Contradiction:

Improvenoise and vibrationVSAvoidtime to reach operating point

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The patent applies periodic action through a controlled, gradual increase in engine speed from idle to target speed. Rather than an immediate jump to target speed, the engine speed increases progressively, which reduces noise and vibration during the transition. The control system manages this gradual speed increase to minimize harmful factors while still reaching the target operating point efficiently.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS9545839B2Hybrid electric vehicle powertrain with enhanced reverse drive performance

Publication Date: 2017.01.17 FORD GLOBAL TECH LLC

AI summary

A method for controlling a hybrid electrical vehicle powertrain having an engine that is a source of power during forward drive and an electric motor that is a source of reverse driving power. A desired engine power during reverse drive is achieved by operating the engine at an increased speed that is greater than an optimum speed for a given engine power.