Engine Control Device for Turbocharger Response and Torque Limiting

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Solution Overview

Problem

Turbocharged engines face a supercharging response delay and torque limitation issues due to the existing control methods, which reduce acceleration performance and impose limitations on output torque, particularly when a torque limiting request is generated, leading to excessive input torque that can damage the transmission system.

Innovation Solution

An engine control device that adjusts the waste gate valve and throttle opening degrees based on load regions, fully opening the waste gate valve in low load regions and the throttle in high load regions, and fully closing the waste gate valve while controlling the throttle to manage torque limiting requests, thereby pre-rotating the turbine and quickly raising supercharging pressure to prevent torque exceeding predetermined limits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the waste gate valve is opened to control supercharging pressure in high load region, then the supercharging pressure can be adjusted, but the turbine cannot be pre-rotated quickly leading to supercharging response delay

Engineering Contradiction:

Improvesupercharging pressure response speedVSAvoidtime for turbine rotation

Core Design Contradiction:

SpeedVSLoss of time

Solution Approach 1:

The waste gate valve is fully closed in advance during high load conditions to direct all exhaust gas flow through the turbine, pre-rotating the turbine before torque limiting is needed. This preliminary action ensures the turbine is already at high speed when torque limiting requests occur, eliminating supercharging response delay.

Inventive Principle:

Principle #10Preliminary action

2Force

If the throttle opening degree is controlled to limit torque, then the output torque can be limited, but the supercharging pressure cannot be quickly increased

Engineering Contradiction:

Improveoutput torque limitationVSAvoidsupercharging pressure increase speed

Core Design Contradiction:

ForceVSSpeed

Solution Approach 1:

The control system segments the torque limitation function into two independent control actions: (1) waste gate valve fully closed to maximize turbine rotation and supercharging pressure buildup, and (2) throttle opening degree adjusted to limit output torque. This segmentation allows both objectives to be achieved simultaneously without conflict.

Inventive Principle:

Principle #1Segmentation

3Stress or pressure

If the waste gate valve opening degree is adjusted to control supercharging pressure, then the supercharging pressure can be maintained, but the turbine rotation speed cannot be maximized for quick response

Engineering Contradiction:

Improvesupercharging pressure controlVSAvoidturbine rotation speed

Core Design Contradiction:

Stress or pressureVSSpeed

Solution Approach 1:

The control system dynamically adjusts waste gate valve operation based on load conditions: fully opened in low load region for normal supercharging pressure control, and fully closed in high load region for maximum turbine rotation speed. This dynamic switching optimizes both pressure control and response speed according to operating 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 reduces supercharging response delay, ensures appropriate torque limitation, and enhances acceleration performance by quickly increasing supercharging pressure, protecting the transmission and improving drivability by controlling the throttle opening degree in response to torque limiting requests.

Implementation Method 1

a turbocharger including a turbine to be driven by exhaust gas and a compressor configured to be driven by the turbine

Methodology Applied

Scientific EffectExhaust gas flow:

Implementation Method 2

the supercharging pressure is controlled by controlling the flow rate of exhaust gas to a turbine using a waste gate valve through which exhaust gas bypasses the section from the inlet side to the outlet side of a turbine

Methodology Applied

Scientific EffectFluid flow control:

Implementation Method 3

a throttle configured to adjust an intake air amount

Methodology Applied

Scientific EffectFluid flow control:

Data Source

PatentUS10704475B2Engine control device

Publication Date: 2020.07.07 SUBARU CORP

AI summary

An engine control device controls an engine. The engine includes a turbocharger, a waste gate valve, and a throttle. In a predetermined low load region, the engine control device performs first control in which the waste gate valve is opened at a predetermined opening degree or more and output adjustment is performed by an opening degree of the throttle. In a predetermined high load region, the engine control device performs second control in which the throttle is opened at a predetermined opening degree or more and output adjustment is performed by an opening degree of the waste gate valve. When a torque limiting request is generated in the high load region, the engine control device performs third control in which the waste gate valve is substantially fully closed and output adjustment is performed by the opening degree of the throttle.