Reverse Engine Spinning for Hydrocarbon Trap Purging

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Solution Overview

Problem

Hybrid electric vehicles face increased bleed emissions due to prolonged periods without fuel combustion, limiting opportunities for purging the air intake system hydrocarbon trap, which can lead to decreased fuel economy and emissions issues.

Innovation Solution

A method where the vehicle engine is spun in reverse by an electric motor during an engine-off condition to purge the air intake system hydrocarbon trap contents to the fuel vapor canister, using an H-bridge circuit to reverse the motor's direction and generate a vacuum for desorbing hydrocarbons, thereby reducing bleed emissions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the vehicle operates in battery-only mode for prolonged periods without fuel combustion, then fuel economy is improved, but the air intake system hydrocarbon trap cannot be purged leading to increased bleed emissions

Engineering Contradiction:

Improvefuel economyVSAvoidbleed emissions

Core Design Contradiction:

Loss of energyVSObject-generated harmful factors

Solution Approach 1:

The system performs preliminary purging action by spinning the engine in reverse before the hydrocarbon trap becomes saturated and causes bleed emissions. The controller monitors engine operating parameters and initiates reverse spinning to desorb and transfer hydrocarbons to the fuel vapor canister proactively, preventing the harmful effect of bleed emissions while maintaining battery-only operation for fuel economy.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The fuel vapor canister serves as an intermediary storage device between the air intake system hydrocarbon trap and the engine combustion system. During reverse engine spinning, hydrocarbons are desorbed from the trap and transferred to the canister, which temporarily holds them until normal engine operation provides an opportunity for combustion, thus preventing direct release to atmosphere.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-generated harmful factors

If the engine is forced on to purge the adsorption beds, then bleed emissions are reduced, but fuel economy decreases

Engineering Contradiction:

Improvebleed emissionsVSAvoidfuel economy

Core Design Contradiction:

Object-generated harmful factorsVSLoss of energy

Solution Approach 1:

The system replaces the traditional mechanical combustion-based purging method with an electrical/electromechanical approach. The electric motor spins the engine in reverse without combustion, using electromagnetic force to drive the engine mechanics and create the necessary vacuum and airflow for hydrocarbon desorption and transfer, eliminating the need for forced combustion.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system changes the operating parameters of the engine by reversing the rotation direction and operating without fuel combustion. This parameter change allows the engine to function as a vacuum pump and airflow generator for purging purposes, achieving emissions control without the energy consumption of combustion-based purging.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If vacuum stored in the fuel tank is used to deliver uncombusted fuel to the canister, then purging is achieved, but the method fails when the fuel tank develops positive pressure

Engineering Contradiction:

Improvepurge operationVSAvoidpurge reliability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The system dynamically adapts the purging mechanism based on operating conditions. Instead of relying on static fuel tank vacuum availability, the system uses active engine reverse spinning to dynamically generate the necessary vacuum and airflow conditions for reliable purging regardless of fuel tank pressure state, ensuring consistent operation across varying thermal and pressure conditions.

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 approach effectively reduces bleed emissions by evacuating uncombusted fuel from the air intake system hydrocarbon trap to the fuel vapor canister, enhancing fuel economy and compliance with zero emissions vehicle standards.

Implementation Method 1

Rotating the vehicle engine in a reverse direction causes atmospheric air to enter an intake of the engine via an exhaust of the engine, desorbing hydrocarbons bound to the air intake system hydrocarbon trap

Methodology Applied

Scientific EffectVacuum: Vacuum

Implementation Method 2

atmospheric air to enter an intake of the engine via an exhaust of the engine, desorbing hydrocarbons bound to the air intake system hydrocarbon trap

Methodology Applied

Scientific EffectDesorption: Desorption

Data Source

PatentUS10183660B2System and methods for purging an air intake system hydrocarbon trap to a fuel vapor canister

Publication Date: 2019.01.22 FORD GLOBAL TECH LLC

AI summary

A method for a vehicle engine is presented, wherein during a first condition, a vehicle controller is placed in a sleep mode following a vehicle-off event and then awoken following a duration, at which time contents of an air intake system hydrocarbon trap are purged to a fuel vapor canister by operating an electric motor to rotate the vehicle engine in a reverse direction. Rotating the vehicle engine in a reverse direction causes atmospheric air to enter an intake of the engine via an exhaust of the engine, desorbing hydrocarbons bound to the air intake system hydrocarbon trap. By porting the desorbed hydrocarbons to the fuel vapor canister, bleed emissions from the air intake system hydrocarbon trap may be reduced.