WO2021249214A1

WO2021249214A1 - Fuel injection control method for direct injection engine

Info

Publication number: WO2021249214A1
Application number: PCT/CN2021/096973
Authority: WO
Inventors: 张慧峰; 欣白宇; 苗志慧; 王强; 龙立; 杜大瑞; 陈昊
Original assignee: 中国第一汽车股份有限公司
Priority date: 2020-06-09
Filing date: 2021-05-28
Publication date: 2021-12-16
Also published as: CN111622855A

Abstract

A fuel injection control method for a direct injection engine, comprising the following steps: S1, detect, by a control system, whether an engine meets a fuel injection condition, if the engine meets a fuel injection condition, continue fuel injection, and if the engine does not meet a fuel injection condition, stop fuel injection; S2, the control system calculates a fuel injection amount needed by the engine in the current working state; S3, the control system determines whether to divide the fuel injection amount into more than two times of injection, in response to a determining result that there is a need to perform more than two times of injection, executes S4, and in response to a determining result that there is no need to perform more than two times of injection, executes S5; S4, the control system determines the number of times of fuel injection, a fuel injection pulse width, and a fuel injection angle, and issues a fuel injection instruction; S5, the control system determines a fuel injection pulse width and a fuel injection angle, and issues a fuel injection instruction.

Description

Method for controlling fuel injection of direct injection engine

This application claims the priority of a Chinese patent application filed with the Chinese Patent Office with an application number of 202010518295.7 on June 9, 2020. The entire content of this application is incorporated into this application by reference.

Technical field

This application relates to the field of automobile technology, for example, to a method for controlling fuel injection of a direct injection engine.

Background technique

With the increasingly stringent emission regulations, the National VI adopts the principle of fuel neutrality, which puts forward higher requirements for cars equipped with gasoline engines. Among them, the number of particulates in gasoline engine emissions (Particulate Number, PN), It needs to be reduced from the transition limit of 6.0×10^12mg/km to 6.0×10^11mg/km required by Phase B of China VI.

At this stage, the technical solution to effectively reduce engine particulate emissions is mainly to use Gasoline Particulate Filter (GPF), which captures and collects particulate matter in the post-emission processing stage before particulate matter enters the atmosphere, effectively reducing the level of emissions. The use of particle traps requires additional investment on the basis of the original engine, which is costly and requires a longer calibration matching time.

In addition, it is also possible to reduce the emission level by increasing the fuel injection pressure and adopting the direct injection fuel system in the high-pressure cylinder of the automobile. However, in some working conditions, such as the case of engine cold start, the solution that only relies on increasing the fuel injection pressure cannot meet the particulate matter emission limit required by the National VI B phase.

Therefore, there is a need for a direct injection engine fuel injection control method to avoid the above situation.

Summary of the invention

The present application provides a method for controlling the fuel injection of a direct injection engine, which can reduce the particle emission of the engine without installing a particle trap, and meet the National VI B emission standard.

The fuel injection control method of a direct injection engine provided in this application includes:

The control system detects whether the engine meets the fuel injection conditions, continues to perform fuel injection in response to the engine meeting the fuel injection conditions, and stops fuel injection in response to the engine does not meet the fuel injection conditions;

The control system calculates the fuel injection quantity required by the engine in the current working state;

The control system determines whether to divide the fuel injection amount into more than two injections. In response to the determination result that more than two injections are required, the control system determines the number of fuel injections, the fuel injection pulse width, and the fuel injection angle, and downloads Send a fuel injection command; in response to the judgment result that there is no need to perform more than two injections, the control system determines the fuel injection pulse width and the fuel injection angle, and issues the fuel injection command.

Description of the drawings

Fig. 1 is a flowchart of a method for controlling fuel injection of a direct injection engine provided by an embodiment of the present application.

detailed description

In the description of this application, it should be noted that the terms "installation", "connection", and "connection" should be understood in a broad sense, unless otherwise clearly specified and limited. For example, it can be a fixed connection or a detachable connection. Connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the internal communication between two components. For those of ordinary skill in the art, the specific meanings of the above-mentioned terms in this application can be understood under specific circumstances.

In this application, unless expressly stipulated and defined otherwise, the "above" or "below" of the first feature of the second feature may include direct contact between the first and second features, or may include the first and second features Not in direct contact but through other features between them. Moreover, "above", "above" and "above" the second feature of the first feature include the first feature being directly above and obliquely above the second feature, or merely indicating that the level of the first feature is higher than that of the second feature. The “below”, “below” and “below” of the second feature of the first feature include the first feature directly below and obliquely below the second feature, or it simply means that the level of the first feature is smaller than the second feature.

In order to reduce the particulate emission of the engine without installing a particulate trap, as shown in FIG. 1, the present application provides a direct injection engine fuel injection control method, including steps S1 to S5.

S1. The control system detects whether the engine meets the fuel injection conditions, if the engine meets the fuel injection conditions, continue fuel injection, if the engine does not meet the fuel injection conditions, stop fuel injection.

S2. The control system calculates the amount of fuel injection required by the engine in the current working state.

S3. The control system judges whether to divide the fuel injection volume into more than two injections. If more than two injections are required, execute S4; if more than two injections are not required, execute S5.

S4. The control system determines the number of injections, injection pulse width and injection angle, and issues injection instructions.

S5. The control system determines the fuel injection pulse width and fuel injection angle, and issues fuel injection instructions.

After the engine is running normally, the control system calculates the fuel injection required by the current engine, and then the control system determines whether more than two injections are required; if more than two injections are not required, the engine is guaranteed to work normally; when more than two injections are performed, it is determined The number of injections, the width of the injection pulse and the angle of the injection, and the issue of injection instructions. Through the above method, when the engine meets the conditions of multiple injections (that is, more than two), the fuel is injected through multiple injections to ensure the fuel efficiency. Atomization effect, thereby improving the combustion conditions, play a role in reducing the amount of particulate matter in engine emissions.

Exemplarily, in step S1, the control system needs to determine whether the engine meets the fuel injection conditions. For example, 1. The engine has an ignition failure; 2. The airbag pops up due to a collision; 3. The anti-theft detection fails; 4. The safety monitoring fuel injection model verification fails; 5. The engine performs super knock protection; 6. The engine is broken Cylinder request; 8. The engine synchronization state is abnormal. When the control system detects any of the above conditions, the engine fuel injection is prohibited, and fuel injection can be performed normally only when all conditions have not occurred. So as to ensure that the engine is in normal working condition, and protect the safety of vehicles and people.

Exemplarily, in step S2, the fuel injection amount is calculated by the intake air amount in the current working state of the engine.

Exemplarily, in step S4, the number of fuel injections determined by the control system is four or five. In step S4, to achieve five injections, at least one of the following conditions must be met. The conditions include: the intake air volume of the engine is greater than the first set intake air volume, the vehicle speed is greater than the first set vehicle speed, and the fuel injection pulse width is greater than or equal to Minimum fuel injection limit, the water temperature of the engine is greater than or equal to the first set water temperature value and less than or equal to the second set water temperature value, and the engine start end time is greater than or equal to the first set time value and less than or equal to the second set value Time value, the car's gearbox is an automatic gearbox, and the catalytic converter is in a heated state. . The above-mentioned conditions can be realized by selecting at least one of them in the control system to be regarded as a condition for achieving five injections. The specific combination mode is not too limited here, and it can be adapted according to the vehicle model and working conditions.

Exemplarily, the first set air intake amount can be determined through calibration according to actual conditions, and the first set vehicle speed can be determined through calibration according to actual conditions. This increases the flexibility of judging whether the five injection conditions are met. Similarly, the minimum fuel injection limit is determined by calibration, the first set water temperature value and the second set water temperature value can be determined by calibration, and the first set time value and the second set time value can be manually calibrated. Sure. Through the above method, the fuel injection volume required in the current working condition can be divided into five injections, so as to ensure that the fuel and air are fully mixed, and the fuel is fully burned, thereby reducing the particulate matter emitted by combustion.

Exemplarily, in step S4, to achieve four fuel injections, at least one of the following conditions must be met, and the conditions include: the intake air volume of the engine is greater than the second set intake air volume, and the engine speed is greater than or equal to the first set speed And less than or equal to the second set speed, the water temperature of the engine is greater than or equal to the third set water temperature value and less than or equal to the fourth set water temperature value, to meet the conditions that need to be met for four injections, including the engine start end time greater than Or equal to the third set time value and less than or equal to the fourth set time value. The conditions mentioned above can be realized by selecting at least one of them in the control system to be regarded as a condition for achieving four injections. The specific combination mode is not too limited here, and it can be adapted according to the vehicle model and working conditions.

Exemplarily, the second set intake air volume can be determined through calibration according to actual needs, and the first set speed and second set speed can be determined through calibration according to actual needs, thereby increasing the determination of whether the four injection conditions are met Flexibility.

Similarly, the third set water temperature value and the fourth set water temperature value can be determined through calibration according to actual needs, and the third set time value and the fourth set time value can be determined through manual calibration according to actual needs. Through the above method, the fuel injection quantity required in the current working condition can be divided into four injections, so as to ensure that the fuel and air are fully mixed, and the fuel is fully burned, thereby reducing the particulate matter emitted by combustion.

Exemplarily, more than two injections can be selected when the engine is in the intake stroke and the compression stroke, so as to ensure that the fuel and air are fully mixed, so that the fuel is fully burned during the combustion work process. Optionally, more than two injections can be selected when the engine is in the intake stroke.

When the engine does not meet the condition of more than two injections, the fuel injection modes of the engine include:

1. Homogeneous single injection, that is, the single fuel injection mode when the engine is running normally.

2. Two injections are used for catalyst heating, that is, the two injection mode when it is judged that the catalyst needs to be heated.

3. High-pressure start injection mode, that is, the injection mode under high-pressure start conditions.

Claims

A method for controlling fuel injection of a direct injection engine includes:

The control system detects whether the engine meets the fuel injection conditions, continues to perform fuel injection in response to the engine meeting the fuel injection conditions, and stops fuel injection in response to the engine does not meet the fuel injection conditions;

The control system calculates the amount of fuel injection required by the engine in the current working state;

The control system determines whether to divide the fuel injection amount into more than two injections. In response to the determination result that more than two injections are required, the control system determines the number of fuel injections, the fuel injection pulse width, and the fuel injection angle, and downloads Send a fuel injection command; in response to the judgment result that there is no need to perform more than two injections, the control system determines the fuel injection pulse width and the fuel injection angle, and issues the fuel injection command.
The method according to claim 1, wherein the control system calculates the fuel injection amount required by the engine in the current working state, comprising: the control system calculates the amount of fuel injection required by the engine in the current working state Calculate the fuel injection quantity.
The method according to claim 1, wherein the control system determines the number of injections, the injection pulse width and the injection angle, and issues an injection instruction, comprising: the number of injections determined by the control system is four Or five times.
The method according to claim 3, wherein it is determined that at least one of the following conditions is met to determine that the number of fuel injections reaches five times: the air intake of the engine is greater than the first set air intake, and the vehicle speed is greater than the first set vehicle speed , The fuel injection pulse width is greater than or equal to the minimum fuel injection limit, the water temperature of the engine is greater than or equal to the first set water temperature value and less than or equal to the second set water temperature value, the automobile gearbox is an automatic gearbox, and a catalytic converter It is heated.
The method according to claim 4, wherein the first set air intake amount is determined through calibration according to actual conditions, and the first set vehicle speed is determined through calibration according to actual conditions.
The method according to claim 4, wherein the minimum fuel injection limit is determined through calibration, and the first set water temperature value and the second set water temperature value can be determined through calibration.
The method according to claim 3, wherein determining that the number of fuel injections reaches four fuel injections needs to meet at least one of the following conditions: the intake air volume of the engine is greater than the second set intake air volume, and the rotational speed of the engine Greater than or equal to the first set speed and less than or equal to the second set speed, the water temperature of the engine is greater than or equal to the third set water temperature value and less than or equal to the fourth set water temperature value.
The method according to claim 7, wherein the second set intake air volume is determined by calibration according to actual needs, and the first set speed and the second set speed are determined by calibration according to actual needs .
8. The method according to claim 7, wherein the third set water temperature value and the fourth set water temperature value are determined by calibration according to actual needs.