Compressor Recirculation and Wastegate Control for Stable Engine Speed

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Internal combustion engines face uncertainties in combustion due to variations in fuel quality and ambient conditions, leading to instability in engine speed control, particularly when the intake throttle is nearly fully open, limiting controllability and steady state brake thermal efficiency.

Innovation Solution

A system and method for controlling the compressor recirculation valve and turbocharger wastegate positions to maintain a target pressure differential across the intake throttle, using feedback control with PID algorithms to stabilize compressor outlet pressure and improve engine performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the intake throttle is near a fully open position to minimize pressure loss, then steady state brake thermal efficiency is improved, but controllability of engine speed is limited due to little change in flow across the valve

Engineering Contradiction:

Improvepressure loss across intake throttleVSAvoidcontrollability of engine speed

Core Design Contradiction:

Loss of energyVSEase of operation

Solution Approach 1:

The patent divides the control function into two independent components: the intake throttle controls pressure differential to minimize energy loss, while the compressor recirculation valve controls engine speed. This segmentation allows each component to optimize its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The compressor recirculation valve acts as an intermediary control element that bypasses the limitation of the intake throttle. By providing an additional control path for air flow, it enables engine speed control without increasing pressure loss across the throttle.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the intake throttle is fully open to improve brake thermal efficiency, then pressure loss is minimized, but engine speed stability deteriorates due to limited flow change capability

Engineering Contradiction:

Improveengine speed stabilityVSAvoidpressure loss across intake throttle

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The control system is segmented into two independent control loops: one managing pressure differential through the intake throttle, and another managing engine speed through the compressor recirculation valve. This allows simultaneous optimization of both energy efficiency and speed stability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes the control parameter from throttle position alone to a combination of throttle position and recirculation valve position. This dual-parameter control enables independent optimization of pressure loss and engine speed stability.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP3728820B1Compressor outlet pressure control for improved engine speed stability and performance using compressor recirculation valve and turbocharger wastegate

Publication Date: 2025.12.31 CUMMINS INC

Figure 1~2
Figure 3~4B
Figure 5

AI summary

Systems, methods and apparatus are disclosed for producing a target compressor outlet pressure that is based on a desired pressure differential across an intake throttle of an internal combustion engine and an intake manifold pressure by opening or closing a compressor recirculation valve and a turbocharger wastegate to commanded positions based on the target compressor outlet pressure.