Hybrid Engine Start via Pre-Spun Electric Machine

Solution Overview

Problem

Hybrid electric vehicles face challenges in starting the engine at low temperatures due to restricted traction battery power, which can lead to the need for additional components like low voltage starters that increase cost and weight, and decrease fuel economy.

Innovation Solution

A method where a controller commands the traction battery to provide power to an electric machine and transmission element to spin at a speed equal to or greater than the engine cranking speed, while the clutch is open, and then locks the clutch to couple rotating inertias and start the engine, minimizing the burden on the traction battery and eliminating the need for a low voltage starter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a low voltage starter is added to assist engine starting at low temperatures, then engine starting reliability is improved, but vehicle weight increases and fuel economy decreases

Engineering Contradiction:

Improveengine starting reliabilityVSAvoidvehicle weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The electric machine is accelerated to a target speed before clutch engagement, storing rotational kinetic energy in advance. This preliminary action allows the engine to be cranked successfully at low temperatures without requiring additional starting components, as the pre-spun electric machine provides the necessary momentum when coupled to the engine through clutch engagement.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The electric machine serves dual functions: it acts as both a propulsion motor during vehicle operation and as an engine starter during cold conditions. By controlling the clutch to engage the electric machine with the engine only when needed for starting, the system eliminates the need for dedicated low voltage starter components while maintaining reliable engine starting capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If a low voltage starter is added to assist engine starting at low temperatures, then engine starting reliability is improved, but manufacturing cost increases

Engineering Contradiction:

Improveengine starting reliabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The electric machine serves dual functions: it acts as both a propulsion motor during vehicle operation and as an engine starter during cold conditions. By controlling the clutch to engage the electric machine with the engine only when needed for starting, the system eliminates the need for dedicated low voltage starter components while maintaining reliable engine starting capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The invention extracts the starting function from a separate low voltage starter component and integrates it into the existing electric machine system. By removing the need for additional starting components and utilizing the high voltage electric machine's existing control systems, the patent reduces manufacturing complexity and cost while achieving reliable cold starting.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If the electric machine is spun to high speed before clutch engagement, then engine starting capability at low temperatures is improved, but energy consumption increases

Engineering Contradiction:

Improveengine starting capabilityVSAvoidbattery power consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The electric machine is accelerated to a target speed before clutch engagement, storing rotational kinetic energy in advance. This preliminary action allows the engine to be cranked successfully at low temperatures without requiring additional starting components, as the pre-spun electric machine provides the necessary momentum when coupled to the engine through clutch engagement.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically controls the clutch engagement timing based on real-time monitoring of electric machine speed. The clutch is engaged only when the electric machine reaches the target speed threshold, optimizing the transfer of rotational energy. This dynamic control ensures that energy is consumed efficiently by the electric machine only when necessary for starting, rather than continuously.

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

Enables successful engine starting at low temperatures without the additional cost and weight of a low voltage starter, by efficiently utilizing the traction battery power and reducing the load on the battery, thus maintaining fuel economy and reducing component costs.

Implementation Method 1

providing power to a motor to spin the motor at a speed at least equal to a target engine cranking speed

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Implementation Method 2

locking the clutch to couple rotating inertias of the motor and a transmission element with the engine

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 3

locking the clutch to couple rotating inertias of the motor and a transmission element with the engine

Methodology Applied

Scientific EffectInertia: Inertia

Data Source

PatentUS9358968B2Cold temperature engine start

Publication Date: 2016.06.07 FORD GLOBAL TECH LLC

AI summary

A method of starting a vehicle may include providing power to a motor to spin the motor at a speed at least equal to a target engine cranking speed while a clutch configured to couple an engine and motor is open. The method may also include cutting power to the motor in response to the motor achieving the speed, and locking the clutch to couple the rotating inertias of the motor and a transmission with the engine to start the engine.