Engine Throttle Valve Control for Negative Pressure Suppression

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Solution Overview

Problem

Existing control systems for internal combustion engines fail to effectively manage negative pressure downstream of a second throttle valve when it malfunctions, leading to issues like excessive turbo supercharger rotation and oil leakage.

Innovation Solution

A control method and device that adjust the valve opening degree of the first throttle valve relative to its target opening degree to maintain balanced pressure and prevent excessive negative pressure development, utilizing a stopper mechanism to restrict the closing rotation of the second throttle valve and ensuring reliable operation even during failures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the second throttle valve is controlled to close fully during engine stop, then the negative pressure downstream is reduced, but the valve cannot respond properly when malfunctioning

Engineering Contradiction:

Improvereliability of pressure controlVSAvoidoperability of second throttle valve

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The first throttle valve acts as an intermediary to indirectly control the negative pressure downstream when the second throttle valve malfunctions. By adjusting the first throttle valve's opening degree, the system can suppress excessive negative pressure development without requiring the malfunctioning second throttle valve to respond properly.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The control device changes the opening degree parameter of the first throttle valve dynamically based on the malfunction state. When the second throttle valve fails, the system adjusts the first throttle valve to a specific opening degree that prevents excessive negative pressure, thereby adapting the system's response to the abnormal condition.

Inventive Principle:

Principle #35Parameter changes

2Stress or pressure

If the second throttle valve closes fully, then negative pressure is suppressed, but excessive negative pressure still develops when the valve fails

Engineering Contradiction:

Improvenegative pressure downstreamVSAvoidreliability during malfunction

Core Design Contradiction:

Stress or pressureVSReliability

Solution Approach 1:

The control device detects malfunction of the second throttle valve in advance and takes preliminary action by adjusting the first throttle valve's opening degree before excessive negative pressure can develop. This preventive measure ensures that even when the second throttle valve fails to close properly, the negative pressure remains within safe limits.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control device continuously monitors the state of the second throttle valve and provides feedback to adjust the first throttle valve accordingly. When malfunction is detected, the feedback loop triggers a change in the first throttle valve's opening degree to compensate for the failure and maintain proper pressure levels.

Inventive Principle:

Principle #23Feedback

3Stress or pressure

If the first throttle valve opening degree is reduced below target, then negative pressure is suppressed, but engine performance may be affected

Engineering Contradiction:

Improvenegative pressure controlVSAvoidengine output

Core Design Contradiction:

Stress or pressureVSProductivity

Solution Approach 1:

The control device applies partial action by adjusting the first throttle valve only to the extent necessary to suppress excessive negative pressure during malfunction conditions. The valve opening degree is reduced below the target only when needed, rather than maintaining a constant restriction, thereby minimizing the impact on engine performance while still achieving pressure control.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentEP3569847B1Method for controlling internal combustion engine and device for controlling internal combustion engine

Publication Date: 2024.02.07 NISSAN MOTOR CO LTD

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AI summary

A turbo supercharger (14) is positioned on the upstream side of a first throttle valve (6) that controls an intake air amount. A second throttle valve (7) that controls an intake pressure is positioned on the upstream side of the turbo supercharger (14). An EGR path (22) that causes part of exhaust gas to flow back is connected between the turbo supercharger (14) and the second throttle valve (7). A flow amount of EGR gas flowing through the EGR path (22) is adjusted by an EGR valve (23). A valve opening degree of the second throttle valve (7) is detected by a second throttle opening degree sensor (34). When the valve opening degree of the second throttle valve (7) is an opening degree on the closed side relative to a target valve opening degree of the second throttle valve (7), first throttle valve opening degree correction by which a valve opening degree of the first throttle valve (6) is controlled to an opening degree further to the closed side than a target valve opening degree of the first throttle valve (6) is performed.