阅读说明：本技术 燃油喷射系统的排空气方法、启动系统及可读存储介质 (Air exhausting method, starting system and readable storage medium of fuel injection system ) 是由 欧天津 石堃 何子奇 于 2020-05-06 设计创作，主要内容包括：本发明提供一种燃油喷射系统的排空气方法、启动系统及可读存储介质,燃油喷射系统的排空气方法包括驱动油泵对一燃油管道内部存在空气的发动机的油轨泵油；获取油轨内部的轨压建立的第一速率,并将第一速率与预设速率比较；若第一速率高于预设速率,则确定发动机为第一类发动机,并驱动喷油器按第一模式工作,直至喷油器达到第一预设目标；若第一速率不高于预设速率,则确定发动机为第二类发动机,并驱动喷油器按第二模式工作,直至喷油器达到第二预设目标。如此,可区分发动机的类别,并针对性地使喷油器按不同的模式工作,而将空气排出。可实现区分不同类别的发动机,并针对性地将空气尽可能排除而不会喷入过量燃油,改善启动困难的问题。(The invention provides an air exhaust method, a starting system and a readable storage medium of a fuel injection system, wherein the air exhaust method of the fuel injection system comprises the steps of driving an oil pump to pump oil to an oil rail of an engine with air in a fuel pipeline; acquiring a first speed established by rail pressure in the oil rail, and comparing the first speed with a preset speed; if the first speed is higher than the preset speed, determining that the engine is a first type of engine, and driving the oil injector to work according to a first mode until the oil injector reaches a first preset target; and if the first speed is not higher than the preset speed, determining that the engine is a second type of engine, and driving the oil injector to work according to a second mode until the oil injector reaches a second preset target. In this way, the engine can be classified and the injectors can be purposefully operated in different modes to expel air. The engine can distinguish different types of engines, air can be removed as far as possible in a targeted mode without injecting excessive fuel, and the problem of difficulty in starting is solved.)

1. An air exhaust method of a fuel injection system, which is applied to an engine with air in a fuel pipeline, is characterized by comprising the following steps:

the driving oil pump pumps oil to an oil rail of an engine with air in a fuel oil pipeline;

acquiring a first speed rate established by the rail pressure in the oil rail, and comparing the first speed rate with a preset speed rate;

if the first speed is higher than the preset speed, determining that the engine is a first type of engine, and driving an oil injector to work according to a first mode until the oil injector reaches a first preset target;

and if the first speed is not higher than the preset speed, determining that the engine is a second type of engine, and driving the oil injector to work according to a second mode until the oil injector reaches a second preset target.

2. The method of bleeding air from a fuel injection system of claim 1, wherein the step of obtaining a first rate of internal rail pressure build-up of the fuel rail and comparing the first rate to a preset rate comprises:

driving the oil pump to work for a first preset time to obtain a first rail pressure in the oil rail;

acquiring a rail pressure preset threshold value of the oil pump working at a preset speed for the first preset time, and comparing the first rail pressure with the rail pressure preset threshold value;

if the first rail pressure is higher than the rail pressure preset threshold value, determining that the first speed is higher than the preset speed; and if the first rail pressure is not higher than the rail pressure preset threshold value, determining that the first speed is not higher than the preset speed.

3. The air bleeding method of a fuel injection system according to claim 1, wherein said process of driving an oil pump to pump oil to an oil rail of said engine includes: driving the oil pump to work for a first preset time to obtain a first rail pressure in the oil rail; continuously driving the oil pump to work for a second preset time;

the first mode includes: the engine does not rotate, and the oil injector injects oil according to a first oil injection pulse width and a first oil injection period; the first preset target includes: the number of times of oil injection of the oil injector reaches a first set value;

the second mode includes: the engine does not rotate, and the oil injector injects oil according to a second oil injection pulse width and a second oil injection period; the second preset target includes: the number of times of oil injection of the oil injector reaches a second set value;

the product of the first oil injection period and the first set value is smaller than the sum of the first preset time and the second preset time; the product of the second injection period and the second set value is smaller than the sum of the first preset time and the second preset time.

4. A method of bleeding air from a fuel injection system as set forth in claim 3 wherein said first injection pulsewidth and said first set point are set in accordance with a relationship including said first rail pressure; the setting basis of the second oil injection pulse width and the second set value comprises the first rail pressure.

5. The air bleeding method of a fuel injection system according to claim 4, wherein the volume of air inside said fuel rail is obtained based on said first rate, and said first injection pulse width and said first set value are set in accordance with the volume of air inside said fuel rail; the second oil injection pulse width and the second set value are set according to the volume of air in the oil rail.

6. A starting system of an engine, which is applied to the engine with air in a fuel pipeline, and is characterized by comprising: the system comprises an oil rail, an oil pump, an oil injector, a rail pressure sensor and a control device;

the oil pump is connected with the oil rail and is in communication connection with the control device;

the oil injector is arranged on the oil rail and is in communication connection with the control device;

the rail pressure sensor is arranged on the oil rail and is in communication connection with the control device; the rail pressure sensor is used for detecting the rail pressure in the oil rail;

the control device is configured to drive the oil pump to pump oil to the oil rail, obtain a first speed rate established by rail pressure inside the oil rail according to a change value of the rail pressure detected by the rail pressure sensor along with time, and compare the first speed rate with a preset speed rate;

if the first speed is higher than the preset speed, the control device determines that the engine is a first type of engine and drives the oil injector to work according to a first mode until the oil injector reaches a first preset target;

and if the first speed is not higher than the preset speed, the control device determines that the engine is a second type of engine and drives the oil injector to work in a second mode until the oil injector reaches a second preset target.

7. The starting system of the engine according to claim 6, characterized in that the starting system of the engine comprises a plurality of oil injectors which are sequentially arranged on the oil rail at intervals and are respectively in communication connection with the control device;

the control device is configured to drive the fuel injector at least at the end of the fuel rail to operate in the first mode or the second mode.

8. The starting system of the engine according to claim 7, characterized in that the control device is configured to drive the plurality of injectors to operate in the first mode or the second mode simultaneously or sequentially.

9. The engine starting system according to claim 6, characterized in that it comprises a diagnostic instrument removably connected in communication with said control device;

the diagnostic instrument is configured to send a command to the control device to cause the control device to drive the injector to operate in the first mode or the second mode while the engine is not rotating.

10. Readable storage medium on which a program is stored, characterized in that the program is executable to implement the method of exhausting air of a fuel injection system according to any one of claims 1 to 5.

Technical Field

The invention relates to the technical field of automobile control, in particular to an air exhaust method, a starting system and a readable storage medium of a fuel injection system.

Background

For the current finished automobile manufacturers, after a new automobile is off-line and fuel is filled, due to the fact that air exists inside fuel pipelines (including a low-pressure oil line, a high-pressure oil line and the like), an oil injector can continuously inject air instead of fuel into a combustion chamber (mainly cold test engine) or inject a large amount of air and a small amount of fuel (mainly hot test engine) in an initial working period, mixed gas is thin, the engine cannot normally combust in the engine, the starting fails, or the air inside the pipelines can be discharged after a starter is dragged for a long time, the starting time is long, and the off-line efficiency of a factory is seriously affected. Fig. 1 shows a test file of the first start when a new vehicle is off-line, wherein a curve Q1 is the engine speed, a curve Q2 is the status bit with a start request, and a curve Q3 is the flag bit for the start of the engine, it can be seen from fig. 1 that the previous three start attempts failed and the start can not be successfully started until the fourth time, and the average time of the previous three starter drags is about 3.5s, but the time of the normal vehicle start is only about 0.5 s. Aiming at the problem, the current commonly used solution solves the problem of difficult starting in a mode of prolonging the oil injection time when the oil injector is started for the first time, the main principle is that when the starter is dragged, the air in the pipeline is quickly discharged by increasing the time of opening the oil injector every time, but the effect of the solution is limited.

Disclosure of Invention

The invention aims to provide an air exhaust method, a starting system and a readable storage medium of a fuel injection system, so as to solve the problem that an engine with air in an existing fuel pipeline is difficult to start.

In order to solve the technical problem, according to a first aspect of the present invention, there is provided an air exhaust method for a fuel injection system, which is applied to an engine having air in a fuel pipeline, the air exhaust method for the fuel injection system comprising: the driving oil pump pumps oil to an oil rail of an engine with air in a fuel oil pipeline;

acquiring a first speed rate established by the rail pressure in the oil rail, and comparing the first speed rate with a preset speed rate;

if the first speed is higher than the preset speed, determining that the engine is a first type of engine, and driving an oil injector to work according to a first mode until the oil injector reaches a first preset target;

and if the first speed is not higher than the preset speed, determining that the engine is a second type of engine, and driving the oil injector to work according to a second mode until the oil injector reaches a second preset target.

Optionally, the step of obtaining a first rate established by the internal rail pressure of the oil rail and comparing the first rate with a preset rate includes:

driving the oil pump to work for a first preset time to obtain a first rail pressure in the oil rail;

acquiring a rail pressure preset threshold value of the oil pump working at a preset speed for the first preset time, and comparing the first rail pressure with the rail pressure preset threshold value;

if the first rail pressure is higher than the rail pressure preset threshold value, determining that the first speed is higher than the preset speed; and if the first rail pressure is not higher than the rail pressure preset threshold value, determining that the first speed is not higher than the preset speed.

Optionally, the process of pumping oil from the driving oil pump to the oil rail of the engine includes: driving the oil pump to work for a first preset time to obtain a first rail pressure in the oil rail; continuously driving the oil pump to work for a second preset time;

the first mode includes: the engine does not rotate, and the oil injector injects oil according to a first oil injection pulse width and a first oil injection period; the first preset target includes: the number of times of oil injection of the oil injector reaches a first set value;

the second mode includes: the engine does not rotate, and the oil injector injects oil according to a second oil injection pulse width and a second oil injection period; the second preset target includes: the number of times of oil injection of the oil injector reaches a second set value;

the product of the first oil injection period and the first set value is smaller than the sum of the first preset time and the second preset time; the product of the second injection period and the second set value is smaller than the sum of the first preset time and the second preset time.

Optionally, the setting basis of the first fuel injection pulse width and the first set value includes the first rail pressure; the setting basis of the second oil injection pulse width and the second set value comprises the first rail pressure.

Optionally, the volume of the air inside the oil rail is obtained based on the first rate, and the setting basis of the first oil injection pulse width and the first set value further includes the volume of the air inside the oil rail; the second oil injection pulse width and the second set value are set according to the volume of air in the oil rail.

In order to solve the above technical problem, according to a second aspect of the present invention, there is provided an engine starting system applied to an engine having air in a fuel pipe, the engine starting system including:

the system comprises an oil rail, an oil pump, an oil injector, a rail pressure sensor and a control device;

the oil pump is connected with the oil rail and is in communication connection with the control device;

the oil injector is arranged on the oil rail and is in communication connection with the control device;

the rail pressure sensor is arranged on the oil rail and is in communication connection with the control device; the rail pressure sensor is used for detecting the rail pressure in the oil rail;

the control device is configured to drive the oil pump to pump oil to the oil rail, obtain a first speed rate established by rail pressure inside the oil rail according to a change value of the rail pressure detected by the rail pressure sensor along with time, and compare the first speed rate with a preset speed rate;

if the first speed is higher than the preset speed, the control device determines that the engine is a first type of engine and drives the oil injector to work according to a first mode until the oil injector reaches a first preset target;

and if the first speed is not higher than the preset speed, the control device determines that the engine is a second type of engine and drives the oil injector to work in a second mode until the oil injector reaches a second preset target.

Optionally, the starting system of the engine includes a plurality of fuel injectors, and the plurality of fuel injectors are sequentially arranged on the fuel rail at intervals and are respectively in communication connection with the control device;

the control device is configured to drive the fuel injector at least at the end of the fuel rail to operate in the first mode or the second mode.

Optionally, the control device is configured to drive the plurality of injectors to operate in the first mode or the second mode simultaneously or sequentially.

Optionally, the starting system of the engine comprises a diagnostic instrument which is detachably connected with the control device in a communication way;

the diagnostic instrument is configured to send a command to the control device to cause the control device to drive the injector to operate in the first mode or the second mode while the engine is not rotating.

In order to solve the above technical problem, according to a third aspect of the present invention, there is provided a readable storage medium having stored thereon a program which, when executed, is capable of implementing the air purge method of the fuel injection system as described above.

In summary, in the air exhaust method, the starting system and the readable storage medium of the fuel injection system provided by the present invention, the air exhaust method of the fuel injection system includes driving an oil pump to pump oil to an oil rail of an engine having air inside a fuel pipeline; acquiring a first speed rate established by the rail pressure in the oil rail, and comparing the first speed rate with a preset speed rate; if the first speed is higher than the preset speed, determining that the engine is a first type of engine, and driving an oil injector to work according to a first mode until the oil injector reaches a first preset target; and if the first speed is not higher than the preset speed, determining that the engine is a second type of engine, and driving the oil injector to work according to a second mode until the oil injector reaches a second preset target. So configured, by obtaining a first rate of rail pressure build-up inside the rail, it is possible to differentiate between engine classes and to purposely operate the fuel injector in different modes to expel air. The air exhaust method of the fuel injection system can realize the purposes of distinguishing different types of engines and pertinently exhausting air as far as possible without injecting excessive fuel, thereby improving the problem of difficult starting.

Drawings

It will be appreciated by those skilled in the art that the drawings are provided for a better understanding of the invention and do not constitute any limitation to the scope of the invention. Wherein:

FIG. 1 is a schematic illustration of a test file first initiated when a new vehicle is taken off-line;

FIG. 2 is a schematic illustration of rail pressure build-up inside the fuel rail when the fuel piping is full of air according to one embodiment of the present invention;

FIG. 3 is a schematic illustration of rail pressure build-up inside the fuel rail when the fuel conduit is full of fuel in accordance with an embodiment of the present invention;

fig. 4 is a flowchart of an air purge method of a fuel injection system according to an embodiment of the present invention.

Detailed Description

To further clarify the objects, advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is to be noted that the drawings are in greatly simplified form and are not to scale, but are merely intended to facilitate and clarify the explanation of the embodiments of the present invention. Further, the structures illustrated in the drawings are often part of actual structures. In particular, the drawings may have different emphasis points and may sometimes be scaled differently.

As used in this specification, the singular forms "a", "an" and "the" include plural referents unless the content clearly dictates otherwise; the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise.

The core idea of the invention is to provide an air exhaust method, a starting system and a readable storage medium of a fuel injection system, so as to solve the problem that the engine starting of the air in the existing fuel pipeline is difficult.

As discussed in the background, some fuel line air-fueled engines have difficulty starting. The inventors have found that there are many situations in an engine where air is present in the fuel line and the amount of air in the fuel line is not the same. For example, when a new vehicle is off-line, there are different situations such as a cold test engine (i.e., an engine which has not been subjected to a factory sampling test and has air inside a fuel pipeline) and a hot test engine (i.e., an engine which has been subjected to a factory sampling test and has part of fuel inside a fuel pipeline) and the like, and if an oil injector is simply opened for a certain time to remove air, insufficient air may be discharged and the engine may be difficult to start; or excessive air exhaust is generated, so that excessive fuel is injected into the cylinder to cause the problems of flooding the cylinder and the like.

In view of the compressibility of gas and the incompressibility of fluid, in combination with the above, the inventors have studied the establishment of rail pressure inside the oil rail:

please refer to fig. 2, which is a schematic diagram of the rail pressure build-up inside the fuel rail when the fuel pipeline is full of air, wherein the abscissa is time in seconds/s, and the ordinate represents different meanings according to different curves. Specifically, the curve Q4 is a flag indicating that the oil pump is operating, and the meaning of the curve in the ordinate direction is 0 or 1, and the value of the curve on the lower side is 0, indicating that the oil pump is not operating; and 1 on the upper side indicates that the oil pump is operated. The curve Q5 is the rail pressure inside the oil rail, which in the direction of the ordinate means the value of the rail pressure in kPa/kPa. As shown in fig. 2, when the rail pressure rises to a predetermined value (the predetermined value is indicated by a horizontal line L1 in the drawing) when the fuel pipe is filled with air, the cumulative operating time of the oil pump is about 8.5 s. It is understood that the predetermined value may be set by one skilled in the art according to various conditions of the engine, such as setting the predetermined value to 600kPa in one example.

Please refer to fig. 3, which is a schematic diagram of the rail pressure build-up inside the fuel rail when the fuel pipeline is full of fuel, wherein the abscissa is time in seconds/s, and the ordinate represents different meanings according to different curves. Specifically, the curve Q6 is a flag indicating that the oil pump is operating, and the meaning of the curve in the ordinate direction is 0 or 1, and the value of the curve on the lower side is 0, indicating that the oil pump is not operating; and 1 on the upper side indicates that the oil pump is operated. The curve Q7 is the rail pressure inside the oil rail, which in the direction of the ordinate means the value of the rail pressure in kPa/kPa. As shown in fig. 3, when the rail pressure rises to a predetermined value (the predetermined value is indicated by a horizontal line L2 in the drawing) when the fuel pipe is filled with fuel, the cumulative operating time period of the oil pump is about 0.15 s. It is understood that the predetermined value may be set by one skilled in the art according to various conditions of the engine, such as setting the predetermined value to 600kPa in one example.

Through the research, the air quantity in the fuel oil pipeline has great influence on the establishment rate of the rail pressure in the fuel oil pipeline, and when the air in the fuel oil pipeline is totally air and the fuel oil is totally fuel oil, the rate differentiation degree of the rail pressure establishment is great, and the difference between the rate differentiation degree and the speed differentiation degree is more than 50 times. It can be understood that, for the hot-test engine, because part of fuel exists in the fuel pipeline, when the rail pressure rises to a preset value, the accumulated working time of the oil pump is between the two conditions, so that the air quantity in the fuel pipeline can be distinguished through the rate of rail pressure establishment, namely, the cold-test engine and the hot-test engine are distinguished, and the air exhaust operation is performed specifically.

Based on the above research, an embodiment of the present invention provides an air exhaust method for a fuel injection system, which is applied to an engine in which air exists inside a fuel pipeline, and includes:

step S1: the driving oil pump pumps oil to an oil rail of an engine with air in a fuel oil pipeline;

step S2: acquiring a first speed rate established by the rail pressure in the oil rail, and comparing the first speed rate with a preset speed rate;

step S3: if the first speed is higher than the preset speed, determining that the engine is a first type of engine, and driving an oil injector to work according to a first mode until the oil injector reaches a first preset target;

step S4: and if the first speed is not higher than the preset speed, determining that the engine is a second type of engine, and driving the oil injector to work according to a second mode until the oil injector reaches a second preset target.

Here, the first rate of rail pressure build-up refers to the gradient of rail pressure rise. Specifically, if the oil pump operates for t hours and the rail pressure rises by r kilopascals, the first speed V is set₁R/t. It should be understood that the time t for the oil pump to operate is the cumulative time for the oil pump to operate. The first type of engine, i.e. the engine representing a relatively small amount of air inside the fuel line, can be understood as a hot-test engine for engines when new vehicles are off-line; the second type of engine, i.e. an engine representing a relatively large amount of air inside the fuel line, can be understood as a cold-test engine for an engine when new is off-line. The preset rate depends on the volume of air inside the cold test engine and the hot test engine and the working capacity of the oil pump, and the preset rate is determined mainly by an actual measurement result and should be a value capable of distinguishing the cold test engine from the hot test engine.

In some embodiments, an engine control system (ECM) can be provided with an oil pre-pumping strategy, and when the whole vehicle is powered on, if the rail pressure inside an oil rail is lower than a certain threshold value, the oil pump is driven to work, and the rail pressure of a low-pressure oil way is established in advance, so that the engine is started smoothly, and before a new vehicle is started for the first time, the new vehicle is generally powered on and some tests are performed, so that the air can be removed by fully utilizing the oil pre-pumping function and the power-on time period, and the condition that a large amount of starting time is occupied for removing the air when the new vehicle is started for the first time is avoided. More specifically, after the assembly of the new vehicle is completed, when a production line worker performs power-on inspection on the new vehicle, the engine is judged to be a cold test engine or a hot test engine through a gradient established by rail pressure inside the oil rail within a first preset time period after power-on (for example, a time period from the initial power-on of a factory to the start of pre-pumping oil to the control of opening air exhaust of an oil injector). For the two engines, the operating modes of the fuel injector are different, so that the aim of exhausting air as much as possible without injecting excessive fuel is achieved. So configured, by obtaining a first rate of rail pressure build-up inside the rail, it is possible to differentiate between engine classes and to purposely operate the fuel injector in different modes to expel air. The air exhaust method of the fuel injection system can realize the purposes of distinguishing different types of engines and pertinently exhausting air as far as possible without injecting excessive fuel, thereby improving the problem of difficult starting.

Optionally, in some embodiments, the step of acquiring a first rate of internal rail pressure establishment of the oil rail and comparing the first rate with a preset rate includes: driving the oil pump to work for a first preset time to obtain a first rail pressure in the oil rail; acquiring a rail pressure preset threshold value of the oil pump working at a preset speed for the first preset time, and comparing the first rail pressure with the rail pressure preset threshold value; if the first rail pressure is higher than the rail pressure preset threshold value, determining that the first speed is higher than the preset speed; and if the first rail pressure is not higher than the rail pressure preset threshold value, determining that the first speed is not higher than the preset speed. Because the comparison of the rates is not intuitive, in order to simplify the comparison process, the method for comparing the first rail pressure inside the oil rail with the preset threshold value when the oil pump works for the first preset time period T1 can be utilized. The preset threshold value is determined mainly by an actual measurement result, preferably, a rail pressure value which can obviously distinguish different types of engines is selected for judgment, when the low-pressure oil pump works for a time period of T1, the engine with the actual rail pressure exceeding the preset threshold value is a hot-test engine, otherwise, the engine is a cold-test engine. It should be noted that, the first preset time period T1 herein also refers to the accumulated operating time period of the oil pump.

Further, the process of pumping oil from the driving oil pump to the oil rail of the engine comprises: driving the oil pump to work for a first preset time period T1, and acquiring a first rail pressure in the oil rail; continuing to drive the oil pump to work for a second preset time period T2; the first mode includes: the engine does not rotate, and the oil injector injects oil according to a first oil injection pulse width and a first oil injection period; the first preset target includes: the number of times of oil injection of the oil injector reaches a first set value; the second mode includes: the engine does not rotate, and the oil injector injects oil according to a second oil injection pulse width and a second oil injection period; the second preset target includes: the number of times of oil injection of the oil injector reaches a second set value; wherein the product of the first injection period and the first set value is less than the sum of the first preset duration T1 and the second preset duration T2; the product of the second injection period and the second setpoint is smaller than the sum of the first predetermined period of time T1 and the second predetermined period of time T2.

The different working modes of the oil injector comprise different settings of oil injection pulse width, oil injection period and oil injection times. It will be appreciated that the total open duration (i.e., exhaust duration) of the injector is the injection pulsewidth x number of injections. The method comprises the steps that the total exhaust duration is controlled by controlling the oil injection times, the oil injection period and the oil injection pulse width of an oil injector according to engines of different types, the three quantities are set to fully exhaust air in an oil rail into a cylinder as far as possible, the principle is that excessive fuel oil cannot be injected into the cylinder to cause flooding of the cylinder, the total opening duration required by the oil injector can be calibrated according to the air volume in a fuel oil pipeline, the rail pressure in the oil rail after oil is pre-pumped, the atmospheric pressure and the static flow of the oil injector, and the oil injector is automatically closed after the oil injection times of the oil injector reach the calibrated set value, so that the air exhaust process is completed. Since the working time of the air discharging process cannot exceed the time of first off-line pre-pumping oil, the product of the oil injection times and the oil injection period is smaller than the total off-line pre-pumping oil time. In addition, the software logic of the present ECM enables operation of the fuel injector only after normal engine rotation is detected, and therefore an additional set of logic is developed to enable operation of the fuel injector according to calibration requirements without engine rotation.

Further, the setting basis of the first oil injection pulse width and the first set value comprises the first rail pressure; the setting basis of the second oil injection pulse width and the second set value comprises the first rail pressure. It can be appreciated that the pulse width and the number of injections of the subsequent injector may vary depending on the first rail pressure of different engines. The setting of the total opening duration (i.e. the exhaust duration) of the injector is based on the first rail pressure, and those skilled in the art will understand that the injection pulse width of the injector should be set within a proper range, the injection pulse width of the injector cannot be too large, so as to avoid damage caused by long-time operation of the injector without fuel cooling, the injection pulse width of the injector cannot be too small, otherwise the injector enters a nonlinear region, which may result in inaccurate air discharge.

Furthermore, the volume of the air in the oil rail is obtained based on the first rate, and the setting of the first oil injection pulse width and the first set value further comprises the volume of the air in the oil rail; the second oil injection pulse width and the second set value are set according to the volume of air in the oil rail. Preferably, the total opening time (i.e. the exhaust time) of the injector is set according to parameters including ambient pressure, static flow rate of the injector at the first rail pressure and the ambient pressure, and volume of air inside the rail. The volume of air inside the rail is obtained on the basis of the first rate, which is understood to mean that, depending on the first rate, the volume of air inside the rail can be determined approximately, which is not an exact value but rather an approximate range. According to the volume of the air in the oil rail, the oil injection frequency, the oil injection pulse width and the oil injection period of the oil injector can be further accurately controlled when the air with different volumes exists.

Based on the above air exhaust method of the fuel injection system, the embodiment of the present invention further provides an engine starting system, which is mainly applied to an engine with air in a fuel pipeline, and the engine starting system includes: the system comprises an oil rail, an oil pump, an oil injector, a rail pressure sensor and a control device; the oil pump is connected with the oil rail and is in communication connection with the control device; the oil injector is arranged on the oil rail and is in communication connection with the control device; the rail pressure sensor is arranged on the oil rail and is in communication connection with the control device; the rail pressure sensor is used for detecting the rail pressure in the oil rail; the control device is configured to drive the oil pump to pump oil to the oil rail, obtain a first speed rate established by rail pressure inside the oil rail according to a change value of the rail pressure detected by the rail pressure sensor along with time, and compare the first speed rate with a preset speed rate; if the first speed is higher than the preset speed, the control device determines that the engine is a first type of engine and drives the oil injector to work according to a first mode until the oil injector reaches a first preset target; and if the first speed is not higher than the preset speed, the control device determines that the engine is a second type of engine and drives the oil injector to work in a second mode until the oil injector reaches a second preset target. In the starting system of the engine, the oil pump is connected with the oil rail through the fuel oil pipeline, the oil injector is arranged on the oil rail, the rail pressure inside the oil rail can be established by driving the oil pump to work, the oil injector is driven to be opened, and then air in the oil rail can be discharged to the cylinder of the engine. The control device may be, for example, an engine control system (ECM).

Generally, the engine includes a plurality of cylinders and a plurality of injectors, the injectors correspond to different cylinders, and the injectors are sequentially disposed on the fuel rail at intervals and are respectively in communication with the control device. A plurality of sprayer set up jointly on same oil rail, the common rail setting promptly. Thus, in one example, the control device may be operable to vent the interior of the rail by controlling operation of a single cylinder fuel injector. Preferably, the control means is arranged to drive the fuel injector at least at the end of the fuel rail to operate in either the first mode or the second mode. Here, the end of the oil rail refers to the end of the oil rail away from the fuel pipe connection. The configuration is more favorable for smooth discharge of air in the oil rail. In some other embodiments, the control device is configured to drive the plurality of injectors to operate in the first mode or the second mode simultaneously or sequentially. Specifically, the injectors corresponding to a plurality of cylinders may be operated simultaneously or sequentially under the drive of the control device. The multi-cylinder fuel injector works simultaneously or sequentially, so that the volume of air exhausted in a single cylinder can be reduced, and the engine can be started for the first time.

Optionally, the starting system of the engine comprises a diagnostic instrument which is detachably connected with the control device in a communication way; the diagnostic instrument is configured to send a command to the control device to cause the control device to drive the injector to operate in the first mode or the second mode while the engine is not rotating. In practice, on a production line, a worker can connect a control device by using a diagnostic instrument and send an instruction to the control device by using the diagnostic instrument, so that the fuel injector can work according to a calibration requirement under the condition that an engine does not rotate.

Preferably, after the air exhausting process is completed, the starting time can be recorded to judge the effectiveness of the air exhausting method and the starting system of the fuel injection system provided by the embodiment. The inventor carries out experiments on the starting system of the engine provided by the embodiment, after the verification of a factory real vehicle, the starting can be successfully started for the first time, the starting time is obviously shortened, compared with the starting method which does not use the fuel injection system provided by the embodiment, the starting can be successfully started for 2-3 times before the starting is successfully started for the first time, the starting time exceeds 3 seconds each time, the starting time is controlled to be about 2 seconds after the starting is successfully started for 1 time by using the air discharging method of the fuel injection system provided by the embodiment, and the problem that a new vehicle is difficult to start for the first time is obviously solved.

Furthermore, the present invention provides a readable storage medium having stored thereon a program which, when executed, is capable of implementing the air purge method of the fuel injection system as described above. Specifically, the air exhaust method of the fuel injection system provided by the invention can be programmed or software, and is stored on the readable storage medium, and in actual use, the program stored in the readable storage medium is used for executing each step of the air exhaust method of the fuel injection system. The readable storage medium may be integrated into a control device (e.g., an engine control system) or a diagnostic device, or may be provided separately in other hardware.

In summary, in the air exhaust method, the starting system and the readable storage medium of the fuel injection system provided by the present invention, the air exhaust method of the fuel injection system includes driving an oil pump to pump oil to an oil rail of an engine having air inside a fuel pipeline; acquiring a first speed rate established by the rail pressure in the oil rail, and comparing the first speed rate with a preset speed rate; if the first speed is higher than the preset speed, determining that the engine is a first type of engine, and driving an oil injector to work according to a first mode until the oil injector reaches a first preset target; and if the first speed is not higher than the preset speed, determining that the engine is a second type of engine, and driving the oil injector to work according to a second mode until the oil injector reaches a second preset target. So configured, by obtaining a first rate of rail pressure build-up inside the rail, it is possible to differentiate between engine classes and to purposely operate the fuel injector in different modes to expel air. The air exhaust method of the fuel injection system can realize the purposes of distinguishing different types of engines and pertinently exhausting air as far as possible without injecting excessive fuel, thereby improving the problem of difficult starting.

The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.