阅读说明：本技术 天然气发动机系统及喷嘴喷射量校正方法 (Natural gas engine system and nozzle injection amount correction method ) 是由 唐仲基 徐亚超 于 2020-05-11 设计创作，主要内容包括：公开了一种用于天然气发动机系统,其控制单元配置成：在喷嘴喷射量检测过程中,控制每个喷嘴依次向发动机供应天然气,并且通过检测发动机排气指标计算每个喷嘴的喷射量；将计算出的每个喷嘴的喷射量与需求喷射量相比较,确定每个喷嘴的喷射量偏差；基于每个喷嘴的喷射量偏差确定针对每个喷嘴的喷射量修正系数；以及在发动机常规运转过程中,基于相应的喷射量修正系数控制每个喷嘴的实际喷射量。还公开了用于天然气发动机系统的天然气喷嘴喷射量校正方法。(Disclosed is a natural gas engine system, a control unit of which is configured to: controlling each nozzle to supply natural gas to the engine in turn during the detection of the injection quantity of the nozzle, and calculating the injection quantity of each nozzle by detecting the exhaust index of the engine; comparing the calculated injection quantity of each nozzle with a required injection quantity, and determining an injection quantity deviation of each nozzle; determining an injection amount correction coefficient for each nozzle based on the injection amount deviation of each nozzle; and controlling an actual injection quantity of each of the nozzles based on the corresponding injection quantity correction coefficient during normal operation of the engine. A natural gas nozzle injection quantity correction method for a natural gas engine system is also disclosed.)

1. A control unit for a natural gas engine system comprising a gas tank (1), a natural gas distributor (2) and an engine (3), the natural gas distributor comprising a plurality of nozzles; the control unit is configured to:

controlling each nozzle to supply natural gas to the engine in turn during the detection of the injection quantity of the nozzle, and calculating the injection quantity of each nozzle by detecting the exhaust index of the engine;

comparing the calculated injection quantity of each nozzle with a required injection quantity, and determining an injection quantity deviation of each nozzle;

determining an injection amount correction coefficient for each nozzle based on the injection amount deviation of each nozzle; and

during normal operation of the engine, the actual injection amount of each nozzle is controlled based on the corresponding injection amount correction coefficient.

2. The control unit according to claim 1, wherein the control unit is configured to execute a nozzle injection amount detection process when the engine is operating at a low speed.

3. The control unit according to claim 1, wherein the control unit is configured to execute a nozzle injection amount detection process during idling after the engine is started and to determine an injection amount correction coefficient therefrom.

4. The control unit according to any one of claims 1 to 3, wherein in the nozzle injection amount detection process, the control unit calculates the injection amount of each nozzle by detecting an oxygen content in engine exhaust gas.

5. The control unit according to any one of claims 1 to 4, wherein the engine includes a plurality of cylinders, and, in the nozzle injection amount detection process, the control unit controls a corresponding one of the nozzles to sequentially supply the natural gas to all of the cylinders in time series in each detection period.

6. The control unit according to any one of claims 1 to 5, wherein the control unit is configured to determine a corresponding correction coefficient based on the injection amount deviation of each nozzle, and to make a correction to the actual injection amount of the corresponding nozzle based on the correction coefficient during normal operation of the engine.

7. The control unit according to claim 6, wherein the control unit is configured to perform the injection amount correction only for nozzles whose injection amount deviation falls outside a deviation limit.

8. The control unit of any one of claims 1 to 7, wherein the control unit is configured to issue a prompt when a deviation in the ejection volume of one or more nozzles exceeds a first threshold; and is

When the deviation of the injection quantity of one or more nozzles exceeds a second threshold value, the absolute value of which is larger than the first threshold value, compulsory measures are taken for the engine, such as limiting the output torque and/or the rotating speed of the engine.

9. The control unit of any one of claims 1 to 8, wherein the control unit is configured to wirelessly transmit the deviation in the amount of ejection of each nozzle to a back-office supervision-side station.

10. A natural gas engine system comprising a gas tank (1), a natural gas distributor (2), an engine (3) and a control unit according to any one of claims 1 to 9.

11. A natural gas nozzle injection amount correction method for a natural gas engine system including a gas tank (1), a natural gas distributor (2) that supplies natural gas from the gas tank to an engine through a plurality of nozzles of the natural gas distributor, and the engine (3);

the nozzle ejection amount correction method includes:

controlling each nozzle to supply natural gas to the engine in turn during the detection of the injection quantity of the nozzle, and calculating the injection quantity of each nozzle by detecting the exhaust index of the engine;

comparing the calculated injection quantity of each nozzle with a required injection quantity, and determining an injection quantity deviation of each nozzle; and

during normal operation of the engine, correction is made to the actual injection quantity of each nozzle based on the injection quantity deviation of the corresponding nozzle.

Technical Field

The application relates to a natural gas engine system and a method for correcting the injection quantity of a natural gas nozzle of the natural gas engine system.

Background

The natural gas engine is an engine using natural gas as fuel. Natural gas engines also have significantly reduced pollutants in the tail compared to fuel engines, and so natural gas engines are of great interest in improving air quality.

For a natural gas engine comprising multiple cylinders, natural gas from a gas reservoir is delivered to each cylinder in a distributor through a plurality of nozzles. Since each nozzle inevitably has some initial structural difference (production tolerance, part tolerance, etc.) and the injection amount of each nozzle drifts with time (the degree of drift of the injection amount of each nozzle is also different), there is a deviation between the actual injection amount and the required injection amount of each nozzle and also a difference between the injection amounts of the nozzles, so that there is a deviation between the actual natural gas intake amount and the required intake amount of each cylinder, thereby affecting the performance and emissions of the entire engine.

Disclosure of Invention

An object of the present application is to provide a natural gas engine system and an injection amount correction method of a natural gas nozzle thereof, capable of detecting and correcting an injection amount deviation of each nozzle.

To this end, the present application provides in one of its aspects a control unit for a natural gas engine system comprising a gas storage tank, a natural gas distributor comprising a plurality of nozzles, and an engine; the control unit is configured to:

controlling each nozzle to supply natural gas to the engine in turn during the detection of the injection quantity of the nozzle, and calculating the injection quantity of each nozzle by detecting the exhaust index of the engine;

comparing the calculated injection quantity of each nozzle with a required injection quantity, and determining an injection quantity deviation of each nozzle;

determining an injection amount correction coefficient for each nozzle based on the injection amount deviation of each nozzle; and

during normal operation of the engine, the actual injection amount of each nozzle is controlled based on the corresponding injection amount correction coefficient.

According to one possible embodiment, the control unit is configured to execute a nozzle injection amount detection process when the engine is operating at a low speed.

According to one possible embodiment, the control unit is configured to execute a nozzle injection amount detection process during idling after the engine is started and thereby determine an injection amount correction coefficient.

According to one possible embodiment, the control unit calculates the injection amount of each nozzle by detecting the oxygen content in the engine exhaust gas during the nozzle injection amount detection.

According to one possible embodiment, the engine includes a plurality of cylinders, and, in the nozzle injection amount detection process, the control unit controls a corresponding one of the nozzles to sequentially supply the natural gas to all of the cylinders in time series in each detection period.

According to one possible embodiment, the control unit is configured to determine a corresponding correction coefficient based on the injection quantity deviation of each nozzle, and to make a correction to the actual injection quantity of the corresponding nozzle based on the correction coefficient during normal operation of the engine.

According to one possible embodiment, the control unit is configured to perform the injection amount correction only for nozzles whose injection amount deviation falls outside the deviation limit.

According to a possible embodiment, the control unit is configured to issue a prompt when the deviation in the injection quantity of one or more nozzles exceeds a first threshold value; and is

When the deviation of the injection quantity of one or more nozzles exceeds a second threshold value, the absolute value of which is larger than the first threshold value, compulsory measures are taken for the engine, such as limiting the output torque and/or the rotating speed of the engine.

According to one possible embodiment, the control unit is configured to wirelessly transmit the deviation in the injection amount of each nozzle to the background supervision-side station.

The present application provides, in another aspect thereof, a natural gas engine system comprising a gas tank, a natural gas distributor, an engine, and a control unit as previously described.

The present application provides in one aspect thereof a natural gas nozzle injection amount correction method for a natural gas engine system including an air tank, a natural gas distributor and an engine, the natural gas distributor supplying natural gas from the air tank to the engine through a plurality of nozzles of the natural gas distributor;

the nozzle ejection amount correction method includes:

controlling each nozzle to supply natural gas to the engine in turn during the detection of the injection quantity of the nozzle, and calculating the injection quantity of each nozzle by detecting the exhaust index of the engine;

comparing the calculated injection quantity of each nozzle with a required injection quantity, and determining an injection quantity deviation of each nozzle; and

during normal operation of the engine, correction is made to the actual injection quantity of each nozzle based on the injection quantity deviation of the corresponding nozzle.

According to the method and the device, the actual injection quantity of each nozzle in the natural gas engine system is detected and compensated accordingly, so that the actual injection quantity of each nozzle is close to the required injection quantity as much as possible, the performance and the emission quality of the whole engine are improved, and the service life of the engine is prolonged.

Drawings

The foregoing and other aspects of the present application will be more fully understood and appreciated by reference to the following detailed description, taken with reference to the accompanying drawings, in which:

FIG. 1 is a schematic illustration of a natural gas engine system according to one possible embodiment of the present application;

fig. 2, 3 are schematic diagrams of the manner in which the injection quantity of each nozzle is detected in the natural gas engine system according to the present application;

FIG. 4 is a schematic view reflecting the ejection volumes of the respective nozzles;

fig. 5 is a schematic diagram of the ejection amount compensation coefficient for each nozzle.

Detailed Description

The present application relates generally to a natural gas engine system, as shown schematically in fig. 1. The natural gas engine system comprises a gas storage tank 1, a natural gas distributor 2, an engine 3 and a control unit 4.

The gas storage tank 1 stores compressed or liquefied natural gas and is provided with a valve (not shown). When the valve is open, the gas tank 1 supplies natural gas to the engine 3 via the distributor 2.

The air container 1 may comprise a single tank body. Alternatively, the air tank 1 may include a plurality of tanks. Multiple tanks may be arranged in series and store the same type of natural gas. Alternatively, a plurality of tanks may be arranged in parallel and store different types of natural gas so as to supply a mixture of different natural gases to the engine 2.

The dispenser 2 comprises an air rail 5, a dispensing chamber 6 and n nozzles I arranged between the air rail 5 and the dispensing chamber 6₁、I₂…I_n. The gas storage tank 1 passes through a pipeline L_NGConnecting the air rail 5 and the pipeline L_NGIn which a pressure regulator (not shown) is arranged. The gas storage tank 1 passes through a pipeline L_NGNatural gas is supplied to the gas rail 5. The natural gas in the gas rail 5 is sprayed through the nozzles towards the distribution chamber 6. Each nozzle may be a high-ejection-volume nozzle (HFI).

The engine 3 includes n cylinders C₁、C₂…C_nThe number of nozzles in the distributor 2 is generally equal to the number of cylinders in the engine 3. The dispensing chamber 6 is connected to the supply pipe L₁、L₂…L_nConnected to the respective cylinder. Each supply pipe leads to an inlet pipe (not shown) of the respective cylinder. During the suction stroke of each cylinder, the natural gas from the distribution chamber 6 mixes with the air sucked into the intake pipe through the corresponding supply pipe and enters the cylinder. The working cycles of the cylinders are separated by a phase angle of 720 DEG/n. The exhaust gas of the engine 3 is discharged through an exhaust pipe 7. An oxygen sensor 8 and other sensors (not shown) are provided in the exhaust pipe 7.

The control unit 4 is connected to the gas tank 1, the natural gas distributor 2 and the engine 3 for controlling their operation, in particular the opening and closing times and the opening time lengths of the individual nozzles of the distributor 2 according to the working cycles of the individual cylinders of the engine 3. The length of time that each nozzle is opened determines the amount of natural gas that is injected by that nozzle for that time.

The control unit 4 is also connected to various sensors in the engine system, including the oxygen sensor 8, for receiving detection data of these sensors, thereby monitoring the operating state of the engine system, and making various necessary adjustments. The control unit 4 includes a memory 9 for storing various data of the engine system, including detection data of various sensors, setting parameters and operating parameters of the engine system, and the like.

As will be understood from the description in the background section, the injection amount of each nozzle may deviate from the required injection amount, and the injection amount may drift over time to increase such a deviation. The present application proposes that the injection quantity (injectability) of each nozzle is detected periodically, and the injection quantity of each nozzle is compensated so that the actual injection quantity of each nozzle approaches the demand injector as closely as possible.

The present application detects the ejection volume (ejection capability) of each nozzle by the following manner: in the nozzle detection process, the control unit 4 controls each nozzle to supply natural gas to all cylinders of the engine 3 in turn, and determines the injection amount (injectability) of each nozzle from the oxygen content in the engine exhaust gas detected by the oxygen sensor 8. This detection process is preferably performed in the case where the engine 3 is operating at a low speed (e.g., idling, particularly, idling after each start of the engine), for example, during idling after each start of the engine.

The above-described detection process of the control unit 4 is schematically shown in fig. 2, 3. First, as shown in fig. 2, in the first detection Period 1, the control unit 4 controls the nozzle I₁To each cylinder C in turn₁、C₂…C_nNatural gas is supplied. The first detection Period 1 may include several engine operation cycles.

FIG. 2 shows the nozzle I as a stepped curve₁Actuation control (open, hold open, close) applied in sequence for each cylinder duty cycle. Nozzle I₁The time of opening is uniform during the working cycle of each cylinder, so that the nozzle I is passed₁The amount of natural gas supplied to each cylinder is substantially equal. At the nozzle I₁During the injection operation performed for all cylinders, the other nozzles remain closed.

In the first detection Period 1, the control unit 4 receives the oxygen content in the exhaust gas in the exhaust pipe 7 from the oxygen sensor 8, and calculates the nozzle I based on the oxygen content in the exhaust gas₁The injection amount of (3). Calculating the nozzle I₁Is recorded in the memory 9.

Period in the first detection Period1, the control unit 4 switches the nozzle to nozzle I₂So that in the second detection Period 2, only the nozzle I is utilized₂Fuel is supplied to each nozzle as schematically shown in fig. 3. Nozzle I₂In the same manner as described above for the nozzle I₁The same is true. In the second detection Period 2, the control unit 4 also receives the oxygen content in the exhaust gas in the exhaust pipe 7 from the oxygen sensor 8, and calculates the nozzle I based on the oxygen content in the exhaust gas₂The injection amount of (3). Calculating the nozzle I₂Is recorded in the memory 9.

After the second detection Period 2 ends, the control unit 4 switches the nozzle to the nozzle I₃And the like until all the nozzles are rotated. Thus, the ejection volumes of the respective nozzles are calculated and recorded in the memory 9.

It is noted that, as an alternative or additional measure to the measure of determining the injection amount (injectability) of each nozzle by detecting the oxygen content in the engine exhaust gas, the control unit 4 may calculate the injection amount of each nozzle by other detected indicators of the exhaust gas (e.g., the content of other components in the exhaust gas, the exhaust gas temperature, the pressure, etc.).

According to one possible embodiment, each nozzle is in the form of a solenoid valve which is open when energized and closed when de-energized. The control process of each nozzle is to apply a high voltage/current to the solenoid valve so that the nozzle is opened, then to apply a low high voltage/current to the solenoid valve instead, keeping the nozzle open, and after the nozzle is opened for a period of time, to de-energize the solenoid valve so that the nozzle is closed. Of course, the nozzles may be actuated in other ways.

Fig. 4 schematically shows the calculated injection quantity Q of each nozzle and the required injection quantity Q of each nozzle₀. Note that the required injection amount Q₀It may not be a fixed value but a value that varies depending on factors such as the engine speed. The calculated ejection volume Q of each nozzle represents their current ejection capability.

The control unit 4 calculates the nozzle injection quantity Q and the required injection quantity Q₀By comparison, it is possible to determine the calculationThe nozzle injection quantity Q and the required injection quantity Q of₀The deviation therebetween. It will be appreciated that some nozzles may have a lower than desired injection volume, which may be due to structural deviations, clogging of the injection passages, and the like. Still other nozzles may have a higher than desired injection volume due to structural deviations, erosion of the injection channels, and the like. Of course, there may be nozzles whose injection quantities may be substantially equal to the required injection quantity, i.e., the injection quantity deviation is within a certain deviation limit (e.g., ± 3%).

Thereafter, the control unit 4 applies the ejection amount compensation coefficient F for each nozzle, for example, as schematically shown in fig. 5. The compensation coefficient F of each nozzle is correlated with the injection amount calculated therefor.

After determining the compensation coefficient F for each nozzle, the control unit 4 corrects the injection amount of each nozzle, for example, the opening time length of each nozzle, based on the compensation coefficient F of each nozzle during the subsequent regular operation of the engine system (for example, during running of the vehicle in which the engine system is installed).

It is noted that during normal operation of the engine system, more than two nozzles may be required to be simultaneously engaged in injection based on engine load. When more than two nozzles are simultaneously involved in a spray, typically each nozzle is opened in turn and when one of the nozzles is not closed, the other nozzle is opened.

According to a possible embodiment, the compensation factor F is a simple multiplication factor, for example as shown in fig. 5, the control unit 4 multiplies the set opening time length of each nozzle by the corresponding compensation factor F to obtain the actual opening time length, and controls the opening of the corresponding nozzle with the actual opening time length. In this way, correction of the actual injection amount of each nozzle is achieved so that the actual injection amount of each nozzle approaches the required injection amount as closely as possible.

Note that the injection amount correction may be performed only for nozzles whose injection amount deviation falls outside the deviation limit (for example, higher than 3% or lower than-3%); the injection amount correction is not performed for the nozzles whose injection amount deviation is within the deviation limit (e.g., ± 3%).

The deviation of the ejection volume (ejection capability) of each nozzle represents the condition of the nozzle. Too large a deviation in the amount of spray means that the nozzle needs to be serviced (e.g. cleaned) or replaced. For this purpose, the control unit 4 records the deviation of the injection quantity (injectability) of each nozzle and the compensation factor F determined therefrom in the memory 9, and, if the deviation of the injection quantity or the compensation factor F exceeds a predetermined threshold value, gives a corresponding prompt and, if necessary, performs a corresponding enforcement measure.

For example, a first threshold value (e.g., ± 5%) and a second threshold value (e.g., ± 10%) having an absolute value greater than the first threshold value may be set. When the control unit 4 determines that the deviation of the injection amount of a certain nozzle exceeds the first threshold value but does not reach the second threshold value (for example, between 5 and 10%, or-5 and-10%), the control unit 4 prompts the user that corresponding maintenance is required, for example, a prompt is given on the dashboard of the vehicle. When the control unit 4 determines that the injection quantity deviation of a certain nozzle exceeds a second threshold (e.g., above 10%, or below-10%), the control unit 4 may take a mandatory action, such as limiting the engine output torque and/or speed, initiating a "limp-home" mode of the vehicle in which the engine system is centralized, and so forth. In this way, the engine may be protected from damage, thereby extending engine life and reducing maintenance costs.

In addition, the control unit 4 may also transmit the deviation of the ejection volume of each nozzle to the background monitoring side station through a wireless networking device. The background monitoring station may monitor the state of the engine system through the received injection quantity deviation of each nozzle, and when the injection quantity deviation of a certain nozzle exceeds a predetermined threshold (for example, the first threshold, the second threshold, and the like described above), send corresponding information to the user or the monitoring agency so as to prompt the user or the monitoring agency to take corresponding measures.

The foregoing describes some possible embodiments of the natural gas engine system and its control unit 4 of the present application. It will be appreciated by those skilled in the art that various adaptations of the foregoing details may be made in accordance with the principles of the present application, which are intended to be within the scope of the following claims.

The present application also provides a natural gas nozzle injection quantity correction method for a natural gas engine system, which performs the detection and correction process described above based on the natural gas engine system and its control unit 4. The various control-related features described above with respect to the natural gas engine system and the control unit 4 thereof are equally applicable to the natural gas nozzle injection quantity correction method of the present application, and will not be described again here.

It should be noted that the natural gas nozzle injection quantity correction scheme of the present application is substantially different from the conventional art scheme in which the natural gas intake quantity is closed-loop adjusted based on the measured value of the oxygen content of the engine exhaust. This closed-loop control of the natural gas intake is characterized by detecting the oxygen content in the engine exhaust in real time during normal engine operation and controlling the natural gas intake of the engine in real time based on the detected oxygen content. The natural gas nozzle injection amount correction scheme of the present application is characterized in that, periodically (for example, after each engine start, a nozzle injection amount detection process is performed in which each nozzle is controlled to supply natural gas to the engine in turn, and then the injection amount of each nozzle is calculated by detecting an engine exhaust index, thereby determining an injection amount deviation of each nozzle and an injection amount correction coefficient for correcting the injection amount deviation; during normal engine operation, it is only necessary to control the actual injection amount of each nozzle based on the corresponding injection amount correction coefficient, it is not necessary to determine the injection amount deviation and the injection amount correction coefficient of each nozzle in real time; therefore, in essence, according to the present application, during normal engine operation, it is no longer necessary to perform closed-loop adjustment of the natural gas intake amount in real time as in the prior art; therefore, the natural gas nozzle injection quantity correction scheme of the present application (without closed-loop regulation) is simpler than prior art closed-loop regulation schemes.

Although the present application has been described herein with reference to particular embodiments, the scope of the present application is not intended to be limited to the details shown. Various modifications may be made to these details without departing from the underlying principles of the application.