Variable Compression Engine Control for Turbo Knocking

Solution Overview

Problem

In variable compression-ratio engines with a turbo supercharger, the rapid rise in supercharging pressure can lead to knocking, which is not effectively suppressed by lowering the compression ratio alone, resulting in deteriorated torque response and reduced fuel efficiency.

Innovation Solution

An engine control device that dynamically adjusts the target compression ratio based on the responsiveness of the supercharging pressure rise, ensuring the mechanical compression ratio is lowered before the supercharging pressure reaches a threshold, thereby preventing knocking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the compression ratio is lowered after knocking is likely to occur, then knocking suppression is achieved, but torque response deteriorates and fuel efficiency is reduced

Engineering Contradiction:

ImproveknockingVSAvoidtorque response

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The control device performs preliminary action by lowering the compression ratio in advance based on predicted knocking likelihood, rather than waiting for knocking to occur. The prediction is made using supercharging pressure rise rate and other parameters, allowing the compression ratio to be adjusted before the harmful effect manifests, thus preventing knocking while maintaining torque response.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts the compression ratio based on real-time operating conditions including supercharging pressure rise rate, engine speed, and load. This dynamic control allows the compression ratio to be optimized for each operating state, achieving knocking suppression while maintaining optimal torque response and fuel efficiency.

Inventive Principle:

Principle #15Dynamics

2Object-affected harmful factors

If the compression ratio is lowered after knocking is likely to occur, then knocking suppression is achieved, but fuel efficiency is reduced

Engineering Contradiction:

ImproveknockingVSAvoidfuel efficiency

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The control device performs preliminary action by lowering the compression ratio in advance based on predicted knocking likelihood, rather than waiting for knocking to occur. The prediction is made using supercharging pressure rise rate and other parameters, allowing the compression ratio to be adjusted before the harmful effect manifests, thus preventing knocking while maintaining torque response.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts the compression ratio based on real-time operating conditions including supercharging pressure rise rate, engine speed, and load. This dynamic control allows the compression ratio to be optimized for each operating state, achieving knocking suppression while maintaining optimal torque response and fuel efficiency.

Inventive Principle:

Principle #15Dynamics

3Speed

If the supercharging pressure rises faster than the compression ratio changing speed, then the supercharger responsiveness is improved, but knocking cannot be suppressed

Engineering Contradiction:

Improvesupercharging pressure rise speedVSAvoidknocking

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The control device performs preliminary action by lowering the compression ratio in advance based on predicted knocking likelihood, rather than waiting for knocking to occur. The prediction is made using supercharging pressure rise rate and other parameters, allowing the compression ratio to be adjusted before the harmful effect manifests, thus preventing knocking while maintaining torque response.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts the compression ratio based on real-time operating conditions including supercharging pressure rise rate, engine speed, and load. This dynamic control allows the compression ratio to be optimized for each operating state, achieving knocking suppression while maintaining optimal torque response and fuel efficiency.

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 suppresses knocking during re-acceleration, improves torque response, and enhances in-use fuel economy by maintaining a low compression ratio in response to rising supercharging pressure.

Implementation Method 1

a supercharger adapted to supply a compressed air to the engine

Methodology Applied

Scientific EffectCompression: Compression

Data Source

PatentUS10344684B2Control device of engine and control method of engine

Publication Date: 2019.07.09 NISSAN MOTOR CO LTD

AI summary

An engine includes a variable compression-ratio mechanism adapted to change a compression ratio of an engine and a supercharger adapted to supply a compressed air to the engine. An engine control device that controls the engine controls the variable compression-ratio mechanism by setting target compression ratio such that the higher responsiveness of a supercharging pressure rise by the supercharger is, the lower the target compression ratio is.