阅读说明：本技术 一种燃气发动机的燃料控制方法及系统 (Fuel control method and system of gas engine ) 是由 盘子林 莫员 李庆飞 王家祥 李勇焕 于 2020-05-28 设计创作，主要内容包括：本发明公开了一种燃气发动机的燃料控制方法,涉及发动机控制,主要解决的是现有燃料控制方式存在控制不准确的技术问题,所述方法包括步骤如下：S1.建立保存有进气总管压力、发动机转速及空燃比的空燃比迈谱；建立空燃比和混合器开度相关的混合器控制曲线；S2.获取发动机的实际转速、实际空燃比、进气总管的实际压力；S3.根据实际转速、实际压力查询空燃比迈谱得到基本空燃比；S4.根据基本空燃比、实际空燃比进行闭环控制得到目标空燃比；S5.根据目标空燃比查询混合器控制曲线得到目标开度,根据目标开度控制混合器运行。本发明还公开了一种燃气发动机的燃料控制系统。本发明通过控制空燃比来直接控制燃料,控制准确,响应速度快。(The invention discloses a fuel control method of a gas engine, which relates to engine control and mainly solves the technical problem that the existing fuel control mode has inaccurate control, and the method comprises the following steps: s1, establishing an air-fuel ratio step spectrum which stores the pressure of an air inlet main pipe, the rotating speed of an engine and the air-fuel ratio; establishing a mixer control curve related to the air-fuel ratio and the opening degree of a mixer; s2, acquiring the actual rotating speed, the actual air-fuel ratio and the actual pressure of an air inlet main pipe of the engine; s3, inquiring an air-fuel ratio spectrum according to the actual rotating speed and the actual pressure to obtain a basic air-fuel ratio; s4, performing closed-loop control according to the basic air-fuel ratio and the actual air-fuel ratio to obtain a target air-fuel ratio; and S5, inquiring a mixer control curve according to the target air-fuel ratio to obtain a target opening degree, and controlling the mixer to operate according to the target opening degree. The invention also discloses a fuel control system of the gas engine. The invention directly controls the fuel by controlling the air-fuel ratio, and has accurate control and high response speed.)

1. A fuel control method of a gas engine, characterized by comprising the steps of:

s1, establishing an air-fuel ratio step spectrum which stores the pressure of an air inlet main pipe, the rotating speed of an engine and the air-fuel ratio; establishing a mixer control curve related to the air-fuel ratio and the opening degree of a mixer;

s2, acquiring the actual rotating speed, the actual air-fuel ratio and the actual pressure of an air inlet main pipe of the engine;

s3, inquiring the air-fuel ratio step spectrum according to the actual rotating speed and the actual pressure to obtain a basic air-fuel ratio;

s4, performing closed-loop control according to the basic air-fuel ratio and the actual air-fuel ratio to obtain a target air-fuel ratio;

s5, inquiring the mixer control curve according to the target air-fuel ratio to obtain a target opening degree, and controlling the mixer to operate according to the target opening degree.

2. The fuel control method of a gas engine according to claim 1, further comprising correcting said target air-fuel ratio before said step S5, comprising the steps of:

s21, establishing a correction stride spectrum which stores the water temperature of the engine, the ambient atmospheric pressure, the air-fuel ratio and the air-fuel ratio correction quantity;

s22, acquiring the actual water temperature of the engine and the actual atmospheric pressure of the environment;

s23, inquiring the correction step spectrum according to the basic air-fuel ratio, the actual water temperature and the actual atmospheric pressure to obtain a basic air-fuel ratio correction amount;

and S24, adding the basic air-fuel ratio correction quantity to the target air-fuel ratio for correction.

3. The fuel control method for a gas engine according to claim 2, wherein the corrected meibomian spectrum is calibrated in a state where the bench simulation ambient atmospheric pressure is < 0.8bar and the engine water temperature is < 60 ℃, and the conditions for correcting the target air-fuel ratio are ambient atmospheric pressure < 0.8bar and the engine water temperature < 60 ℃.

4. The fuel control method for a gas engine according to claim 1, wherein the gas pressure at the inlet of the mixer is 1.01bar to 1.04 bar.

5. The fuel control method of a gas engine according to claim 1, wherein said mixer is a venturi mixer.

6. A fuel control system of a gas engine is characterized by comprising an engine rotating speed monitoring unit, an air-fuel ratio monitoring unit, an air inlet main pipe pressure monitoring unit, an engine water temperature monitoring unit, an atmospheric pressure monitoring unit, a storage unit, a logic operation unit and a control unit, wherein the logic operation unit is respectively connected with the engine rotating speed monitoring unit, the air-fuel ratio monitoring unit, the air inlet main pipe pressure monitoring unit, the engine water temperature monitoring unit, the atmospheric pressure monitoring unit, the storage unit and the control unit; the storage sheet is used for storing an air-fuel ratio spectrum, a mixer control curve and a correction spectrum; the logic operation unit is used for acquiring actual rotating speed through the engine rotating speed monitoring unit, acquiring actual air-fuel ratio through the air-fuel ratio monitoring unit, acquiring actual pressure through the air inlet main pipe pressure monitoring unit, acquiring actual water temperature through the engine water temperature monitoring unit, acquiring actual atmospheric pressure through the atmospheric pressure monitoring unit, acquiring target opening according to the method of any one of claims 1-5, sending the target opening to the control unit, and controlling the mixer to operate through the control unit according to the target opening.

Technical Field

The present invention relates to engine control, and more particularly, to a fuel control method and system for a gas engine.

Background

When the pressure range of supplied gas is 1.01 bar-1.04 bar (absolute pressure), the fuel control system of the gas engine for low-pressure power generation at present adopts closed-loop control on the pressure of an engine intake manifold to control the opening of a mixer, thereby realizing the control on the fuel of the gas engine. The control strategy of the prior art is shown in fig. 1, and an intake manifold pressure curve of an engine is inquired according to the engine speed and the engine power percentage to obtain an intake manifold pressure target value, and closed-loop control is performed according to the intake manifold pressure target value and an intake manifold pressure actual value to obtain the opening of a mixer. Because the control strategy is too simple, the fuel is only indirectly controlled according to the pressure of the air inlet manifold, and when the engine operates under multiple working conditions, the conditions of inaccurate control and delayed control exist in the fuel control, so that the engine can knock or be unstable in operation.

In addition, the current control system has no correction effect on the control of fuel under different ambient atmospheric pressure and engine water temperature, which further deteriorates the running stability of the engine under the condition of large difference of environmental conditions.

Disclosure of Invention

The present invention is directed to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a fuel control method for a gas engine, which is accurate in control and fast in response speed.

The invention also aims to provide a fuel control system of the gas engine, which is accurate in control and high in response speed.

In order to achieve the above object, the present invention provides a fuel control method of a gas engine, the method comprising the steps of:

s1, establishing an air-fuel ratio step spectrum which stores the pressure of an air inlet main pipe, the rotating speed of an engine and the air-fuel ratio; establishing a mixer control curve related to the air-fuel ratio and the opening degree of a mixer;

s2, acquiring the actual rotating speed, the actual air-fuel ratio and the actual pressure of an air inlet main pipe of the engine;

s3, inquiring the air-fuel ratio step spectrum according to the actual rotating speed and the actual pressure to obtain a basic air-fuel ratio;

s4, performing closed-loop control according to the basic air-fuel ratio and the actual air-fuel ratio to obtain a target air-fuel ratio;

s5, inquiring the mixer control curve according to the target air-fuel ratio to obtain a target opening degree, and controlling the mixer to operate according to the target opening degree.

As a further improvement, before the step S5, the method further includes correcting the target air-fuel ratio, and includes the following steps:

s21, establishing a correction stride spectrum which stores the water temperature of the engine, the ambient atmospheric pressure, the air-fuel ratio and the air-fuel ratio correction quantity;

s22, acquiring the actual water temperature of the engine and the actual atmospheric pressure of the environment;

s23, inquiring the correction step spectrum according to the basic air-fuel ratio, the actual water temperature and the actual atmospheric pressure to obtain a basic air-fuel ratio correction amount;

and S24, adding the basic air-fuel ratio correction quantity to the target air-fuel ratio for correction.

Furthermore, the correction step spectrum is calibrated in a state that the bench simulation environment atmospheric pressure is less than 0.8bar and the engine water temperature is less than 60 ℃, and the conditions for correcting the target air-fuel ratio are that the environment atmospheric pressure is less than 0.8bar and the engine water temperature is less than 60 ℃.

Further, the gas pressure at the inlet of the mixer is 1.01 bar-1.04 bar.

Further, the mixer is a venturi mixer.

In order to achieve the second purpose, the invention provides a fuel control system of a gas engine, which comprises an engine rotating speed monitoring unit, an air-fuel ratio monitoring unit, an air intake main pipe pressure monitoring unit, an engine water temperature monitoring unit, an atmospheric pressure monitoring unit, a storage unit, a logic operation unit and a control unit, wherein the logic operation unit is respectively connected with the engine rotating speed monitoring unit, the air-fuel ratio monitoring unit, the air intake main pipe pressure monitoring unit, the engine water temperature monitoring unit, the atmospheric pressure monitoring unit, the storage unit and the control unit; the storage sheet is used for storing an air-fuel ratio spectrum, a mixer control curve and a correction spectrum; the logic operation unit is used for acquiring actual rotating speed through the engine rotating speed monitoring unit, acquiring actual air-fuel ratio through the air-fuel ratio monitoring unit, acquiring actual pressure through the air inlet main pipe pressure monitoring unit, acquiring actual water temperature through the engine water temperature monitoring unit, acquiring actual atmospheric pressure through the atmospheric pressure monitoring unit, acquiring target opening according to the method, sending the target opening to the control unit, and controlling the mixer to operate according to the target opening by the control unit.

Advantageous effects

Compared with the prior art, the invention has the advantages that: the invention obtains the basic air-fuel ratio according to the actual rotating speed and the actual pressure, performs closed-loop control according to the basic air-fuel ratio and the actual air-fuel ratio to obtain the target air-fuel ratio, controls the mixer to operate according to the target air-fuel ratio, directly controls the fuel by controlling the air-fuel ratio, has accurate control and fast response speed, and can improve the applicability of the gas engine under different working conditions; in addition, the target air-fuel ratio is corrected according to the actual water temperature and the actual atmospheric pressure, so that the accuracy of the target air-fuel ratio can be further improved, the control precision of fuel is improved, the fuel of the gas engine can be accurately controlled even in special environments (plateau and cold environments), and the applicability of the engine in different environments is improved.

Drawings

FIG. 1 is a control block diagram of a conventional technique;

fig. 2 is a control block diagram of the present invention.

Detailed Description

The invention will be further described with reference to specific embodiments shown in the drawings.

Referring to fig. 2, a fuel control method of a gas engine, the method includes the steps of:

s1, establishing an air-fuel ratio step spectrum which stores the pressure of an air inlet main pipe, the rotating speed of an engine and the air-fuel ratio; establishing a mixer control curve related to the air-fuel ratio and the opening degree of a mixer;

s2, acquiring the actual rotating speed, the actual air-fuel ratio and the actual pressure of an air inlet main pipe of the engine;

s3, inquiring an air-fuel ratio spectrum according to the actual rotating speed and the actual pressure to obtain a basic air-fuel ratio;

s4, performing closed-loop control according to the basic air-fuel ratio and the actual air-fuel ratio to obtain a target air-fuel ratio;

and S5, inquiring a mixer control curve according to the target air-fuel ratio to obtain a target opening, and controlling the mixer to operate according to the target opening so as to further realize control on fuel entering the engine.

Further, before step S5, the method further includes correcting the target air-fuel ratio, and includes the following steps:

s21, establishing a correction stride spectrum which stores the water temperature of the engine, the ambient atmospheric pressure, the air-fuel ratio and the air-fuel ratio correction quantity;

s22, acquiring the actual water temperature of the engine and the actual atmospheric pressure of the environment;

s23, inquiring a correction spectrum according to the basic air-fuel ratio, the actual water temperature and the actual atmospheric pressure to obtain a correction quantity of the basic air-fuel ratio;

s24, adding the basic air-fuel ratio correction quantity to the target air-fuel ratio for correction, and further improving the control precision of the engine fuel.

The correction of the manometers is to calibrate under the conditions that the atmospheric pressure of the bench simulation environment is less than 0.8bar and the water temperature of the engine is less than 60 ℃, the conditions are that the atmospheric pressure of the environment is less than 0.8bar and the water temperature of the engine is less than 60 ℃ when the target air-fuel ratio is corrected, and the engine can be suitable for different working environments.

In the embodiment, the gas pressure at the inlet of the mixer is 1.01 bar-1.04 bar, the gas pressure is absolute pressure, and the gas is supplied under the pressure, so that the method can achieve optimal control. The mixer is a Venturi mixer, and negative pressure is formed in the mixer by utilizing air intake of an engine to generate Venturi effect so that gas is sucked and fully mixed in the mixer.

A fuel control system of a gas engine comprises an engine rotating speed monitoring unit, an air-fuel ratio monitoring unit, an air inlet main pipe pressure monitoring unit, an engine water temperature monitoring unit, an atmospheric pressure monitoring unit, a storage unit, a logic operation unit and a control unit, wherein the logic operation unit is respectively connected with the engine rotating speed monitoring unit, the air-fuel ratio monitoring unit, the air inlet main pipe pressure monitoring unit, the engine water temperature monitoring unit, the atmospheric pressure monitoring unit, the storage unit and the control unit; the storage list is used for storing an air-fuel ratio spectrum, a mixer control curve and a correction spectrum; the logic operation unit is used for acquiring actual rotating speed through the engine rotating speed monitoring unit, acquiring actual air-fuel ratio through the air-fuel ratio monitoring unit, acquiring actual pressure through the air inlet main pipe pressure monitoring unit, acquiring actual water temperature through the engine water temperature monitoring unit, acquiring actual atmospheric pressure through the atmospheric pressure monitoring unit, acquiring target opening according to the method, sending the target opening to the control unit, and controlling the mixer to operate according to the target opening by the control unit.

The invention obtains the basic air-fuel ratio according to the actual rotating speed and the actual pressure, performs closed-loop control according to the basic air-fuel ratio and the actual air-fuel ratio to obtain the target air-fuel ratio, controls the mixer to operate according to the target air-fuel ratio, directly controls the fuel by controlling the air-fuel ratio, has accurate control and fast response speed, and can improve the applicability of the gas engine under different working conditions; in addition, the target air-fuel ratio is corrected according to the actual water temperature and the actual atmospheric pressure, so that the accuracy of the target air-fuel ratio can be further improved, the control precision of fuel is improved, the fuel of the gas engine can be accurately controlled even in special environments (plateau and cold environments), and the applicability of the engine in different environments is improved. The invention can make the performance of the engine more excellent and the adaptability of the engine better.

The above is only a preferred embodiment of the present invention, and it should be noted that it is obvious to those skilled in the art that several variations and modifications can be made without departing from the structure of the present invention, which will not affect the effect of the implementation of the present invention and the utility of the patent.