Off-Road Gas Engine Mixer Pressure Feedback for Air-Gas Ratio Control

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Solution Overview

Problem

Current mixers in non-road gas engines face challenges in achieving precise control of air-gas ratios due to low control accuracy and limited control range, especially in venturi and proportional mixers, which affect engine performance.

Innovation Solution

A gas control system with a mixer equipped with pressure sensors and a pressure regulating valve, connected to a controller, that adjusts the air-gas ratio by measuring pressures at the air inlet, gas inlet, and mixed gas outlet, allowing for closed-loop control and precise adjustment of the air-gas ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a venturi mixer is used to achieve uniform mixing of gas and air, then mixing quality is improved, but control accuracy deteriorates due to difficulty in controlling flow rates at air inlet and air outlet

Engineering Contradiction:
Improvemixing qualityVSAvoidcontrol accuracy
Core Design Contradiction:
Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The patent implements a feedback control system by installing pressure sensors at the air inlet, gas inlet, and mixed gas outlet, connected to a controller that adjusts the pressure regulating valve based on real-time pressure information. This closed-loop feedback mechanism enables precise control of the air-gas ratio while maintaining uniform mixing quality.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces the traditional mechanical flow rate control mechanism with a pressure-based control system. By using pressure sensors and a pressure regulating valve controlled by electronic feedback, the system achieves more accurate control compared to purely mechanical flow control methods in venturi mixers.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If a proportional mixer is used to control air-gas ratio by adjusting inner core opening degree, then control flexibility is improved, but response speed deteriorates and control range is insufficient

Engineering Contradiction:
Improvecontrol flexibilityVSAvoidresponse speed
Core Design Contradiction:
Adaptability or versatilityVSSpeed

Solution Approach 1:

The patent replaces the slow mechanical adjustment of inner core opening with an electronically controlled pressure regulating valve. The valve opening degree is adjusted based on real-time pressure feedback from sensors, enabling much faster response speed while maintaining control flexibility across a wider range.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements a dynamic control system where the pressure regulating valve opening is continuously adjusted based on real-time pressure information from sensors. This dynamic adjustment mechanism enables the system to respond quickly to changing operating conditions, improving response speed compared to static or manually adjusted proportional mixers.

Inventive Principle:
Principle #15Dynamics

3Measurement precision

If pressure sensors and controller are added to achieve precise closed-loop control of air-gas ratio, then control accuracy is improved, but device complexity increases

Engineering Contradiction:
Improvecontrol accuracyVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent integrates multiple functions into a unified control system. The pressure sensors serve dual purposes of monitoring and control feedback, the controller manages both pressure regulation and mixing optimization, and the pressure regulating valve performs both pressure control and flow ratio adjustment. This multi-functionality reduces the need for separate dedicated components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Ease of manufacture

If traditional mixers are used with simple structure, then manufacturing cost is reduced, but control range and performance are insufficient

Engineering Contradiction:
Improvemanufacturing costVSAvoidcontrol range
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent adds a cost-effective feedback control mechanism using pressure sensors and a controller. This relatively low-cost addition enables precise control of the air-gas ratio and expands the operational control range, achieving high performance without requiring a complete redesign of the mixer structure.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent controls the air-gas ratio by adjusting the pressure parameter through the pressure regulating valve, rather than changing the physical structure of the mixer. This parameter-based control approach maintains the simple mixer structure while expanding the control range and performance capabilities.

Inventive Principle:
Principle #35Parameter changes

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

The system achieves high accuracy and a smaller control range for air-gas ratios, improving transient response speed and reducing manufacturing costs while maintaining good performance.

Implementation Method 1

the pressure transmission passage is capable of transmitting a pressure difference at the mixed gas outlet to the working chamber, wherein a movement of the working chamber enables the air inlet and the gas inlet to be opened

Methodology Applied
Scientific EffectPressure difference: Pressure Gradient

Implementation Method 2

the elastic assembly includes a diaphragm and a spring; one end of the diaphragm is annularly connected to the end face of the sleeve away from the mixed gas outlet, the other end of the diaphragm is annularly connected to an end face of the upper cover

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3677769B1Gas control system and gas control method of off-road gas engine
Publication Date: 2024.02.14 WEICHAI POWER CO LTD
  • EP3677769B1 patent drawingFigure 1
  • EP3677769B1 patent drawingFigure 2
  • EP3677769B1 patent drawing

AI summary

A gas control system of a non-road gas engine and a gas control method thereof are disclosed by the present disclosure. The gas control system includes a mixer, the mixer is provided with an air inlet, a gas inlet and a mixed gas outlet respectively, the air inlet is provided with a first pressure sensor, the gas inlet is provided with a second pressure sensor and a pressure regulating valve that are spaced apart, and the mixed gas outlet is provided with a third pressure sensor; the first pressure sensor, the second pressure sensor, the pressure regulating valve and the third pressure sensor are respectively electrically connected to a controller, and the controller controls an opening degree of the pressure regulating valve according to pressure information fed back by the first pressure sensor, the second pressure sensor and the third pressure sensor so as to adjust an air-gas ratio of the mixed gas. The system has a simple structure. By disposing a pressure regulating valve at the gas inlet, the pressure of the gas entering the mixer is controlled, and the air-gas ratios required under various working conditions are controlled, which realizes a closed-loop control so that a control range of the air-gas ratio is smaller, the accuracy is higher, and a transient response speed of the engine is improved.