Hybrid Engine Variable Valve Timing Control for Canister Purge and OBD

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Solution Overview

Problem

Hybrid electric vehicles face challenges in optimizing engine variable valve timing to improve fuel efficiency while ensuring adequate canister purge and satisfying On-board diagnostics (OBD) diagnosis, as existing control methods restrict engine negative pressure, leading to insufficient canister purge and impaired OBD diagnosis.

Innovation Solution

A control method for engine variable valve timing that includes a fuel efficiency prioritized intake/exhaust cam control mode and a normal intake/exhaust cam control mode, where the cam position is set based on canister loading amount and diagnosis completion, allowing for optimized cam position control to enhance fuel efficiency and engine negative pressure, thereby addressing OBD diagnosis issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the intake/exhaust cam is controlled to be at a retarded position to maximize fuel efficiency, then fuel efficiency is improved, but engine negative pressure decreases leading to insufficient canister purge and impaired OBD diagnosis

Engineering Contradiction:

Improvefuel efficiencyVSAvoidcanister purge amount

Core Design Contradiction:

Use of energy by moving objectVSQuantity of substance

Solution Approach 1:

The patent applies dynamics by making the cam position control adaptive rather than fixed. The ECU dynamically adjusts the cam position based on real-time operating conditions (canister loading amount, diagnosis status, engine load, RPM) to optimize both fuel efficiency and canister purge performance. This resolves the contradiction by allowing the system to switch between retarded positions (for fuel efficiency) and advanced positions (for canister purge) as needed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the control parameter (cam position) based on different operating conditions. By monitoring canister loading amount, engine load, and RPM, the ECU adjusts the cam position parameter to achieve the desired balance between fuel efficiency and canister purge. When canister purge is needed, the cam position is advanced to increase negative pressure; when fuel efficiency is the priority and canister is not full, the cam position is retarded.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If the intake/exhaust cam is controlled to be at a retarded position to maximize fuel efficiency, then fuel efficiency is improved, but OBD diagnosis capability is impaired

Engineering Contradiction:

Improvefuel efficiencyVSAvoidOBD diagnosis capability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The system dynamically adjusts cam position control based on diagnosis status. When OBD diagnosis is required, the ECU temporarily advances the cam position to enable proper diagnosis even if this temporarily reduces fuel efficiency. When diagnosis is not needed and canister is not full, the system maintains retarded cam position for optimal fuel efficiency. This dynamic switching resolves the contradiction between fuel efficiency and diagnostic reliability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system performs preliminary checks of canister loading amount and diagnosis status before determining cam position. By anticipating when diagnosis will be needed or when canister purge is required, the ECU proactively adjusts cam position in advance, ensuring both fuel efficiency optimization and maintenance of diagnostic capability when needed.

Inventive Principle:

Principle #10Preliminary action

3Power

If the cam position is advanced to increase valve overlap, then engine output power increases, but fuel efficiency decreases

Engineering Contradiction:

Improveengine output powerVSAvoidfuel efficiency

Core Design Contradiction:

PowerVSUse of energy by moving object

Solution Approach 1:

The patent changes the cam position parameter based on engine operating conditions (load, RPM, canister status). At high load conditions where power is needed, the cam position is advanced to increase valve overlap and improve engine output. At low to medium load conditions where fuel efficiency is priority and canister purge is not needed, the cam position is retarded to reduce valve overlap and improve fuel efficiency. This conditional parameter adjustment resolves the contradiction between power and fuel efficiency.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10605176B2Control method for engine variable valve timing of hybrid electric vehicle

Publication Date: 2020.03.31 HYUNDAI MOTOR CO LTD

AI summary

A method for controlling an engine variable valve timing of a hybrid electric vehicle, may include providing a cam position setting table of a fuel efficiency prioritized intake/exhaust cam control mode, and a cam position setting table of a normal intake/exhaust cam control mode, the cam position setting table of the fuel efficiency prioritized intake/exhaust cam control mode being differentiated from the cam position setting table of the normal intake/exhaust cam control mode; selecting one of the fuel efficiency prioritized intake/exhaust cam control mode and the normal intake/exhaust cam control mode by a canister loading amount and whether or not diagnosis of an intake cam and diagnosis of an exhaust cam are completed; and determining position control values of the intake and exhaust cams by using the cam position setting table and then controlling positions of the intake cam and the exhaust cam by the determined position control values.