A control method and device for reducing the generation of a gas machine PN and an engine

Abstract

The present application relates to a kind of control method, device and engine for reducing the generation amount of gas machine PN, obtain the operating state data of engine, extract operating speed and throttle opening, according to empirical formula, if engine current is in idle threshold range and throttle threshold range, and after the duration exceeds the set threshold, condition A is met;When condition A is met, the current engine speed and throttle opening are taken, the difference between the engine speed and throttle opening corresponding to the step length of last step is determined respectively, and the corresponding time integral is done, to obtain the time integral of speed difference and the time integral of throttle opening difference;When both exceed the corresponding calibration threshold, engine current condition meets condition B;When condition A and condition B are met simultaneously, the opening pressure of piston cooling nozzle is controlled to increase by a set value.The opening pressure of oil nozzle is controlled to reduce the injection amount of oil by identifying low load condition and load mutation condition.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of engine control technology, in particular to a control method and device for reducing the generation of PN of a gas engine and the gas engine. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] PN in the engine emission standard, full name: particle number, is used to evaluate the number of fine particles with a diameter exceeding a certain threshold (such as 23nm). PN emission is an important index newly added in the motor vehicle emission standard in recent years, aiming to more strictly control the particulate matter emission in motor vehicle exhaust to improve air quality.

[0004] In the engine using gas as fuel (such as methane) (commonly known as gas engine), the combustion product of methane does not produce PN. The main source of PN in the gas engine is the oil for internal lubrication and cooling of the piston, which is caused by the negative pressure of the intake valve due to the throttle valve air retention at low load, and then is sucked into the combustion chamber and burned. In the related technologies of combustion control and exhaust treatment of the gas engine, there is almost no related scheme to reduce the generation of PN of the gas engine, so that the PN generated by the gas engine is ignored. SUMMARY

[0005] In order to solve the technical problems existing in the background art, the present application provides a control method and device for reducing the generation of PN of a gas engine and the gas engine. After identifying a specific working condition, the working condition of load mutation is further judged. When the load mutation occurs, the opening pressure of the oil nozzle is controlled to reduce the injection amount of the oil, so as to reduce the combustion of the oil in the cylinder and reduce the generation of PN.

[0006] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0007] The first aspect of the present application provides a control method for reducing the generation of PN of a gas engine, comprising the following steps:

[0008] Obtaining the running state data of the engine, extracting the running speed and the throttle opening degree;

[0009] According to the empirical formula, when the current running speed and the throttle opening degree of the engine are within the corresponding threshold range and the duration exceeds the set threshold, the engine is in a low load working condition;

[0010] In the low load working condition, the current engine speed and throttle opening are taken to determine the difference between the engine speed and the throttle opening corresponding to the previous step length, and the corresponding time integral processing is performed to obtain the time integral of the speed difference and the time integral of the throttle opening difference, and when both of them exceed the corresponding calibration threshold, the engine enters the load mutation working condition;

[0011] When the engine enters the load mutation working condition from the low load working condition, the opening pressure of the piston cooling nozzle is increased by a set value.

[0012] Further, the empirical formula is determined according to the bench test or vehicle test of the engine.

[0013] Further, if the engine is not currently in the idle threshold range and the throttle threshold range, the running data is continuously acquired.

[0014] Further, when the engine is in the idle threshold range and the throttle threshold range, if the duration does not exceed the set threshold, the low load working condition is not met, and the running data is continuously acquired.

[0015] Further, the calibration threshold is calibrated according to the empirical formula determined according to the bench test or vehicle test of the engine, and the speed difference integral and the throttle opening difference integral between adjacent step lengths are calibrated.

[0016] Further, the current engine speed and throttle opening are taken to determine the difference between the engine speed and the throttle opening corresponding to the previous step length, and the corresponding time integral processing is performed, specifically:

[0017] The current engine speed and the engine speed of the previous step length are taken to obtain the speed difference, and the time integral of the obtained speed difference is performed to obtain the time integral of the speed difference;

[0018] The current throttle opening and the throttle opening of the previous step length are taken to obtain the throttle opening difference, and the time integral of the obtained throttle opening difference is performed to obtain the time integral of the throttle opening difference.

[0019] Further, if the engine only meets the low load working condition or only meets the load mutation working condition, the opening pressure of the piston cooling nozzle remains unchanged.

[0020] The second aspect of the application provides a control device for reducing the amount of gas machine PN, comprising:

[0021] The data collector is used for acquiring the running state data of the engine and extracting the running speed and the throttle opening;

[0022] A controller is configured to determine the control instruction of increasing the opening pressure of the piston cooling nozzle according to the empirical formula, the operating speed and the throttle opening degree when the engine enters the load mutation working condition from the low load working condition.

[0023] A third aspect of the present application provides an engine equipped with the control device for reducing the PN generation amount of the gas machine.

[0024] Further, the piston cooling nozzle of the engine performs the oil injection at the set opening pressure according to the instruction of the controller.

[0025] Compared with the prior art, the above one or more technical solutions have the following beneficial effects:

[0026] According to the characteristics that the fuel combustion of the gas fuel engine (gas machine) does not generate PN, the operating data is used to determine the operating condition of the engine in the low load area, and then the condition of load mutation is determined, so as to identify the throttle gas trapping and intake negative pressure phenomenon caused by the engine entering the load mutation condition from the low load condition, and to try to reduce the oil injection amount by increasing the opening pressure of the piston cooling nozzle to the extent possible, so as to reduce the PN generated by the oil being sucked into the combustion chamber to participate in the combustion caused by the negative pressure. BRIEF DESCRIPTION OF DRAWINGS

[0027] The drawings accompanying the specification of the present application form a part thereof and serve to provide further understanding of the present application, the exemplary embodiments of the present application and its description serve to explain the present application, and do not constitute an improper limitation of the present application.

[0028] Figure 1 is a control flow diagram for reducing the PN generation amount of the gas machine provided by one or more embodiments of the present application;

[0029] Figure 2 is a flow diagram for determining whether the engine is in a specific working condition during the period of reducing the PN generation amount of the gas machine provided by one or more embodiments of the present application;

[0030] Figure 3 is a flow diagram for determining whether the engine is in a load mutation working condition during the period of reducing the PN generation amount of the gas machine provided by one or more embodiments of the present application. DETAILED DESCRIPTION

[0031] The present application will be further described below in conjunction with the drawings and embodiments.

[0032] It should be pointed out that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as generally understood by those skilled in the art to which the present application belongs.

[0033] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0034] Terminology explanation:

[0035] Gas engine, refers to the engine using gas as fuel, such as natural gas engine.

[0036] PN, particle number, refers to the total number of particles with a particle size greater than 23 nm in the engine exhaust after removing volatile substances.

[0037] As introduced in the background, the engine using gas as fuel is more environmentally friendly than the traditional oil engine, so that the PN generated by the gas engine is easily ignored, and the combustion product of methane as fuel in the gas engine does not produce PN. The main source of PN in the gas engine is the oil for internal lubrication and cooling of the piston, which is caused by the negative pressure of the intake valve due to the low load, and then is sucked into the combustion chamber and burned. The related scheme almost does not consider how to reduce the PN generation of the gas engine.

[0038] Therefore, the following embodiments give a control method, device and engine for reducing the PN generation of the gas engine. By identifying the specific working condition, the working condition of load mutation is further judged. When the load mutation occurs, the opening pressure of the oil nozzle is controlled to reduce the injection amount of the oil, so as to reduce the combustion of the oil in the cylinder and reduce the PN generation.

[0039] Embodiment one:

[0040] A control method for reducing the PN generation of the gas engine, comprising the following steps:

[0041] Obtaining the running state data of the engine, extracting the running speed and the throttle opening degree;

[0042] According to the empirical formula, when the current running speed and the throttle opening degree of the engine are within the corresponding threshold range, and the duration exceeds the set threshold, the engine is in a low load working condition;

[0043] In the low load condition, the current engine speed and throttle opening are taken to determine the difference between the engine speed and throttle opening corresponding to the previous step, and the corresponding time integral processing is performed to obtain the time integral of the speed difference and the time integral of the throttle opening difference. When both of them exceed the corresponding calibration threshold, the engine enters the load mutation condition;

[0044] When the engine enters the load mutation condition from the low load condition, the opening pressure of the piston cooling nozzle is increased by a set value.

[0045] In this embodiment, the control process for reducing the amount of gas machine PN is as shown in Figure 1 According to the test experience of the bench and the whole vehicle, the running data collected is effectively judged by continuously monitoring and collecting the real-time running state data of the engine.

[0046] If the current running state meets the requirements of a specific condition, proceed to the next calculation; if the current condition does not meet the requirements of a specific condition, do nothing and continue monitoring.

[0047] When the current running state meets the requirements of a specific condition, further judge whether it is in the load mutation condition. If it is not in the load mutation condition, the piston cooling nozzle maintains normal opening pressure; if it is in the load mutation condition, the piston cooling nozzle maintains high pressure opening state for a certain time.

[0048] Considering that the main source of gas machine PN is the oil for internal lubrication and cooling of the piston, which is caused by the negative pressure of intake air due to throttle choking at low load, and is burned after being sucked into the combustion chamber, it is first judged that the current running state meets the low load condition, and on this basis, it is further judged whether it is in the load mutation condition, so as to identify the situation of entering the load mutation condition from the low load condition.

[0049] First, judge the low load condition to identify the state of throttle choking. In the low load condition, the speed and load of the engine are relatively low, and accordingly, the air required by the gas machine is also low. At this time, the throttle is in a partially closed state, which will limit the air flow into the gas machine, thereby forming a negative pressure in the intake pipe. This negative pressure is necessary for the normal operation of the engine, which helps to suck in air and mix with fuel to form combustible mixture.

[0050] At the same time, this negative pressure will also suck in a certain amount of oil, especially in the low load condition, the speed and load of the engine are relatively low, resulting in relatively low pressure and temperature in the cylinder. At this time, the sealing performance of the oil may be affected, especially when the sealing performance of the piston, cylinder liner and other parts is poor, the oil may enter the combustion chamber through the tiny gap.

[0051] When the engine is switched from low load condition to load mutation condition, the pressure and temperature in the cylinder will rise rapidly. This sharp change will cause greater challenges to the sealing performance of the engine. If the state of the sealing elements (such as piston rings, cylinder liners, etc.) is not good or has been damaged at this time, the engine oil is more likely to be sucked into the combustion chamber.

[0052] Under the load mutation condition, the engine oil sucked into the combustion chamber will burn at high temperature, producing blue smoke and polluting the air. At the same time, the combustion of engine oil will also form carbon deposits at the valve, intake port, piston top, piston ring, etc., affecting the performance and service life of the engine. In addition, if the combustion of engine oil is incomplete, a part of the engine oil will also be discharged with the exhaust gas, which also produces PN.

[0053] Therefore, the present scheme increases the opening pressure of the piston cooling nozzle by a set value when the engine is switched from low load condition to load mutation condition, artificially increases the opening pressure of the oil nozzle, reduces the amount of engine oil injected into the piston to a certain extent, and indirectly reduces the amount of engine oil sucked in, thereby reducing the PN generated.

[0054] It should be noted that the judgment criteria for low load condition of different types of gas machines are different. In the present embodiment, the "low load condition" introduced above is referred to as a specific condition.

[0055] For convenience of description, the judgment condition of the specific condition is referred to as condition A in the present embodiment. After condition A is met, it needs to be continuously monitored to determine whether the load mutation condition is met. The load mutation condition is referred to as condition B. When both condition A and condition B are met, the action of "reducing the PN generation amount" is triggered, that is, the action of "controlling the oil injection amount or oil injection pressure of the piston cooling nozzle" is triggered. This step is referred to as execution C. After the execution of step C, there will be a significant control effect on the current exhaust PN, and the expected target will be finally achieved.

[0056] In the present embodiment, the specific condition can be considered as a running condition of the engine in the low load region. After determining that the engine is in the running condition of the low load region according to the running data, the load mutation condition is determined on this basis, so as to identify the intake negative pressure phenomenon caused by throttle choke and try to reduce the injection amount of engine oil to a certain extent to reduce the PN generated by the engine oil sucked into the combustion chamber for combustion.

[0057] The judgment process of condition A includes the following steps:

[0058] 1. Obtain the running speed and throttle opening degree of the engine, and use the empirical formula of the bench test to determine whether it is in the running boundary of the low load region. When the running boundary requirement is met, trigger the counter to time the running time. When the running boundary requirement is not met, continuously monitor and wait for the condition to be met.

[0059] 2. When the requirements of the operating boundary are met, the counter is activated to run. When the duration reaches a certain threshold, it is determined that condition A is met.

[0060] In this embodiment, the determination process of condition A, as shown in Figure 2 , includes the following steps:

[0061] The operating speed of the engine and the throttle opening are obtained;

[0062] According to the empirical formula, it is determined whether the engine is currently in the idle threshold range and the throttle threshold range. If yes, the counter starts running. If not, the relevant data is continuously monitored.

[0063] When the running time of the counter exceeds the threshold, it is considered that the engine is in a specific working condition. If it does not exceed the threshold, the relevant data is continuously monitored.

[0064] The determination process of condition B, as shown in Figure 3 , includes the following steps:

[0065] 1. After condition A is met, condition B is determined.

[0066] 2. Take the difference between the current engine speed and the engine speed of the previous step. Time integral of the speed difference between the previous and current steps. According to the empirical formula, determine the calibration threshold of the difference.

[0067] 3. Take the difference between the current throttle opening and the throttle opening of the previous step. Time integral of the throttle opening difference between the previous and current steps. According to the empirical formula, determine the calibration threshold of the difference.

[0068] 4. When the time integral of the speed difference and the time integral of the throttle opening difference both exceed the corresponding calibration threshold, it is considered that the current condition of the engine meets condition B, i.e. the engine is in a load mutation working condition.

[0069] In this embodiment, the calibration threshold is the upper limit of the difference.

[0070] After conditions A and B are met, C is executed, specifically: the opening pressure of the piston cooling nozzle is increased by a set value to reduce the injection amount of oil, thereby reducing the amount of oil combustion in the cylinder and indirectly reducing the amount of PN generation. When either condition A or condition B is not met, the opening pressure of the piston cooling nozzle remains unchanged.

[0071] In this embodiment, the specific content of C is: when conditions A and B are met, the opening pressure of the oil nozzle of the electronically controlled piston cooling nozzle is increased by 50hpa, reducing the injection amount of oil, reducing the combustion of oil in the cylinder, and reducing the amount of PN generation. When conditions A or B are not met, the opening pressure of the electronically controlled piston cooling nozzle remains unchanged.

[0072] Regarding the electronically controlled piston cooling nozzle, the engine piston needs to be cooled in the working state. By setting the inner cooling oil channel on the piston, the cooling oil is sprayed into the piston inner cooling oil channel from the piston cooling nozzle installed on the cylinder block, thereby reducing the temperature of the piston, reducing the thermal load of the piston, and improving combustion. The cooling oil may be sucked into the combustion chamber in some cases to participate in combustion, thus generating PN.

[0073] The scheme given in this embodiment first identifies that the engine enters a certain specific working condition (generally in the low load range) and that the intake negative pressure caused by the throttle valve pressure build-up may occur when the load mutation occurs on this basis, and without affecting the piston cooling performance, the opening pressure of the oil nozzle is considered to be increased, thereby appropriately reducing the amount of oil sprayed into the piston, and thus reducing the amount of oil sucked into the combustion chamber, indirectly reducing the generation amount of PN.

[0074] Embodiment two:

[0075] A control device for reducing the PN generation amount of a gas machine, comprising:

[0076] A data collector for acquiring the running state data of the engine and extracting the running speed and the throttle opening;

[0077] A controller configured to determine the "increase opening pressure" control instruction to the piston cooling nozzle when the engine enters the load mutation working condition from the low load working condition according to the empirical formula, the running speed and the throttle opening.

[0078] By identifying that the engine enters a certain specific working condition (generally in the low load range) and that the intake negative pressure caused by the throttle valve pressure build-up may occur when the load mutation occurs on this basis, and without affecting the piston cooling performance, the opening pressure of the oil nozzle is considered to be increased, thereby appropriately reducing the amount of oil sprayed into the piston, and thus reducing the amount of oil sucked into the combustion chamber, indirectly reducing the generation amount of PN.

[0079] Embodiment three:

[0080] An engine equipped with a control device for reducing the PN generation amount of a gas machine.

[0081] The piston cooling nozzle of the engine sprays oil at the set opening pressure according to the instruction issued by the controller.

[0082] After being mounted on a gaseous fuel engine (gas engine), by identifying that the engine enters a certain specific working condition (generally in the low load range) and on this basis, the intake negative pressure condition caused by the throttle choke pressure that may be generated when the load suddenly changes, and without affecting the piston cooling performance, the opening pressure of the oil nozzle is considered to be improved, thereby appropriately reducing the amount of oil injected into the piston, and thus reducing the amount of oil sucked into the combustion chamber, and indirectly reducing the generation amount of PN.

[0083] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A control method of reducing the amount of PN generation in a gas engine, characterized by, The method comprises the following steps: acquiring the running state data of the engine, extracting the running speed and the throttle opening; according to the empirical formula, when the current running speed and the throttle opening of the engine are within the corresponding threshold range and the duration exceeds the set threshold, the engine is in a low load condition; in the low load condition, taking the current engine speed and throttle opening, respectively determining the difference between the engine speed and the throttle opening corresponding to the previous step length, and performing corresponding time integration processing to obtain the time integral of the speed difference and the time integral of the throttle opening difference, and when both of them exceed the corresponding calibration threshold, the engine enters the load mutation condition; when the engine enters the load mutation condition from the low load condition, the opening pressure of the piston cooling nozzle is increased by a set value.

2. The control method of claim 1, wherein The empirical formula is determined according to the bench test or vehicle test of the engine.

3. The control method of claim 1, wherein the control method is characterized by: If the engine is not currently within the speed threshold range and the throttle threshold range, continue to acquire the running data.

4. The control method of claim 1, wherein If the engine is within the speed threshold range and the throttle threshold range, and the duration does not exceed the set threshold, the low load condition is not met, and the running data is continuously acquired.

5. The control method of claim 1, wherein the control method is characterized by: The calibration threshold is an empirical formula determined according to the bench test or vehicle test of the engine, which calibrates the threshold of the speed difference integral and the throttle opening difference integral between adjacent step lengths.

6. The control method of claim 1, wherein Taking the current engine speed and throttle opening, respectively determining the difference between the engine speed and the throttle opening corresponding to the previous step length, and performing corresponding time integration, specifically: Taking the current engine speed and the engine speed of the previous step length, subtracting the speed difference, and performing time integration on the obtained speed difference to obtain the time integral of the speed difference; Taking the current throttle opening and the throttle opening of the previous step length, subtracting the throttle opening difference, and performing time integration on the obtained throttle opening difference to obtain the time integral of the throttle opening difference.

7. The control method of claim 1, wherein the control method is a method of reducing the amount of PN generated by a gas machine, characterized by If the engine only meets the low load condition or only meets the load mutation condition, the opening pressure of the piston cooling nozzle remains unchanged.

8. Control device for implementing the method according to any one of claims 1 to 7, characterized in that, It comprises: a data collector for acquiring the running state data of the engine and extracting the running speed and the throttle opening; a controller configured to determine the control instruction of "increasing the opening pressure" to the piston cooling nozzle when the engine enters the load mutation condition from the low load condition according to the empirical formula, the running speed and the throttle opening.

9. An engine characterized by, The control device for reducing the PN generation amount of the gas machine according to claim 8 is installed.

10. The engine of claim 9, wherein, The piston cooling nozzle of the engine performs oil injection at the set opening pressure according to the instruction issued by the controller.

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