CN116181482A - System fault diagnosis method, electronic equipment and readable storage medium - Google Patents
System fault diagnosis method, electronic equipment and readable storage medium Download PDFInfo
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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Abstract
The invention provides a system fault diagnosis method, electronic equipment and a readable storage medium, wherein the fault diagnosis method comprises the steps of firstly obtaining the maximum value and/or the minimum value of an exhaust back pressure actual measurement value corresponding to the current lift of each cylinder; obtaining the maximum value and/or the minimum value of the expected exhaust back pressure value corresponding to the target lift of each cylinder; and giving out an initial diagnosis result of the exhaust back pressure of each cylinder according to the maximum value of the corresponding actual exhaust back pressure value and the maximum value of the expected exhaust back pressure value of each cylinder under the corresponding lift system and/or according to the minimum value of the corresponding actual exhaust back pressure value and the minimum value of the expected exhaust back pressure value of each cylinder under the corresponding lift system, and obtaining a single or multiple cylinder lift switching diagnosis result according to the system state fed back by the engine control system when the exhaust back pressure is abnormal. The system fault diagnosis method provided by the invention realizes the identification and diagnosis of whether the lift switching of a single cylinder or a plurality of cylinders in the engine is successful.
Description
Technical Field
The present invention relates to the field of vehicle system control technologies, and in particular, to a system fault diagnosis method, an electronic device, and a readable storage medium.
Background
With the rapid development of the automobile and internal combustion engine industries, energy demand and environmental protection problems become the problems faced by the countries in the world today, and therefore, energy conservation and emission reduction have become two major subjects of the development of the internal combustion engine industry. In the aspect of energy conservation, automobile manufacturers at home and abroad improve the combustion work-doing process of an engine, reduce pumping loss of small and medium loads and improve the fuel economy of a traditional gasoline engine by applying technologies such as Atkinson (Atkinson) circulation, miller (Miller) circulation, high/low pressure EGR, a high-efficiency turbocharging system represented by a variable-section turbocharger (variable geometric turbocharger) and the like. Wherein, miller (Miller) cycle engine realizes early closing (Early Intake Valve Closing) of intake valve by controlling intake VVT, thereby achieving the purpose of reducing pumping loss and improving combustion efficiency. However, because the intake camshaft with single lift cannot meet the requirements of fuel economy and dynamic performance of the engine under different working conditions, a two-step intake VVL system capable of realizing large/small lift switching is generated; the fuel economy is improved by using the large/small lift according to different working conditions of the engine, namely, realizing Miller (Miller) circulation by utilizing the small lift aiming at small and medium loads; the Otto (Otto) cycle is implemented with a large lift for medium and high loads, thereby ensuring engine dynamics.
At present, although the two-step intake VVL system can furthest meet the requirements of the engine on fuel economy and dynamic performance under different working conditions, in the process of realizing large/small lift switching, the condition of single-cylinder or even multi-cylinder intake cam shaft large/small lift switching failure can occur due to the failure of a mechanical structure, so that the combustion stability of the engine is reduced, and knocking and misfire of the engine can be caused under extreme conditions. Aiming at the large/small lift switching faults of the two-step intake VVL system, the existing rationality diagnosis strategy in the current EMS system can only carry out fault diagnosis under the condition that the switching of all cylinder lifts fails; aiming at the condition that the lift switching of a single cylinder or part of cylinders fails, the current diagnosis principle is limited, and the large/small lift switching failure can not be effectively identified and corresponding failure post-treatment can not be carried out.
Therefore, how to provide a new system fault diagnosis method to overcome the above-mentioned drawbacks in the prior art is becoming one of the technical problems to be solved by those skilled in the art.
Disclosure of Invention
The invention aims to provide a system fault diagnosis method, electronic equipment and a readable storage medium, which are used for solving the problem that the fault diagnosis cannot be carried out on single-cylinder or partial cylinder lift switching failure in the prior art.
In order to achieve the above object, the present invention provides a system failure diagnosis method, which is applicable to a two-stage intake VVL system based on an exhaust back pressure sensor, comprising:
judging whether the enabling condition of system fault diagnosis is met according to the system state fed back by the engine control system, and if so, executing the following steps:
according to the measured voltage signals of the exhaust back pressure sensor and the crankshaft rotating speed sensor, obtaining the maximum value and/or the minimum value of the corresponding exhaust back pressure measured value of each cylinder of the current lift of the engine in the exhaust stroke;
obtaining the maximum value and/or the minimum value of the expected exhaust back pressure value of each cylinder in the target lift according to the current exhaust flow of the engine;
obtaining a lift switching preliminary diagnosis result of each cylinder according to the maximum value of the exhaust back pressure measured value of each cylinder corresponding to the current lift and the maximum value of the exhaust back pressure expected value corresponding to the target lift, and/or obtaining an exhaust back pressure preliminary diagnosis result of each cylinder at the current lift according to the minimum value of the exhaust back pressure measured value of each cylinder corresponding to the current lift and the minimum value of the exhaust back pressure expected value corresponding to the target lift;
and if the preliminary diagnosis result of the exhaust back pressure is abnormal, obtaining a single or multiple cylinder lift switching diagnosis result according to the system state fed back by the engine control system.
Optionally, the enabling conditions of the system fault diagnosis include:
and the engine control system triggers the zone bit of the switching of the two-stage intake VVL system, the current engine rotating speed reaches the preset rotating speed, and the exhaust back pressure sensor is electrically normal.
Optionally, the obtaining, according to the measured voltage signals of the exhaust back pressure sensor and the crankshaft rotation speed sensor, a maximum value and/or a minimum value of an actual exhaust back pressure value of each cylinder of the current lift in the exhaust stroke of the engine includes:
obtaining an actual measurement value of the exhaust back pressure of the engine crank angle at the current lift; obtaining the maximum value and/or the minimum value of the measured value of the exhaust back pressure of the engine crank angle in each crank angle interval;
and obtaining the maximum value and/or the minimum value of the exhaust back pressure measured value of each cylinder in the current lift according to the cylinder corresponding to each crank angle interval and the maximum value and/or the minimum value of the exhaust back pressure measured value in each crank angle interval.
Optionally, the obtaining the preliminary diagnosis result of the exhaust back pressure of each cylinder at the current lift includes:
calculating a difference value between a maximum value of the exhaust back pressure measured value corresponding to the current lift and a maximum value of the exhaust back pressure expected value corresponding to the target lift of each cylinder, and/or calculating a difference value between a minimum value of the exhaust back pressure measured value corresponding to the current lift and a minimum value of the exhaust back pressure expected value corresponding to the target lift of each cylinder;
comparing the difference of the maximum values of each cylinder with a first preset threshold value, and/or comparing the difference of the minimum values of each cylinder with the first preset threshold value;
and when the difference value of the maximum value of the current lift of the cylinder is larger than a first preset threshold value, or the difference value of the minimum value of the current lift of the cylinder is larger than the first preset threshold value, judging that the exhaust back pressure of the cylinder is abnormal.
Optionally, the obtaining the preliminary diagnosis result of the exhaust back pressure of each cylinder at the current lift includes:
comparing the maximum value of the exhaust back pressure measured value of all the cylinders at the current lift with each other and/or comparing the minimum value of the exhaust back pressure measured value of all the cylinders at the current lift with each other;
and if the difference between the maximum value of the measured exhaust back pressure value of one cylinder at the current lift and the maximum value of the measured exhaust back pressure value of each other cylinder at the current lift is larger than a second preset threshold value, or if the difference between the minimum value of the measured exhaust back pressure value of one cylinder at the current lift and the minimum value of the measured exhaust back pressure value of each other cylinder at the current lift is larger than the second preset threshold value, judging that the exhaust back pressure of the cylinder is abnormal.
Optionally, if the preliminary diagnosis result of the exhaust back pressure is that the exhaust back pressure is abnormal, obtaining a single or multiple cylinder lift switching diagnosis result according to a system state fed back by the engine control system, including:
detecting whether an interference factor exists in the engine control system according to the system state fed back by the engine control system;
if the exhaust back pressure of the single or multiple cylinders is abnormal, judging that the interference factors cause the exhaust back pressure of the single or multiple cylinders;
if not, determining that the single or multiple cylinder lift switching failure causes the exhaust back pressure abnormality.
Optionally, the preset interference factors include: the cylinder is misfiring.
Optionally, the determining that the interference factor causes the exhaust back pressure of the single or multiple cylinders to be abnormal includes:
acquiring the current lift and a target lift of the engine;
if the current lift of the engine is a small lift and the target lift is a large lift: acquiring an engine air-fuel ratio, and judging that the single or multiple cylinders are in fire so as to cause abnormal exhaust back pressure of the single or multiple cylinders when the engine air-fuel ratio is smaller than a preset air-fuel ratio value;
if the current lift of the engine is a large lift and the target lift is a small lift: acquiring the air-fuel ratio of the engine, and if the air-fuel ratio of the engine is smaller than a preset air-fuel ratio value; and acquiring an engine knock sensor signal, and judging that the exhaust back pressure is abnormal due to failure of switching of single or multiple cylinder lifts of the engine when the engine knock sensor signal is larger than a preset signal value.
In order to achieve the above object, the present invention further provides an electronic device, including a processor and a memory, where the memory stores a computer program, and the computer program implements the system fault diagnosis method according to any one of the above when executed by the processor.
In order to achieve the above object, the present invention also provides a readable storage medium having stored therein a computer program which, when executed by a processor, implements the system fault diagnosis method of any one of the above.
Compared with the prior art, the system fault diagnosis method, the electronic equipment and the readable storage medium provided by the invention have the following beneficial effects:
the system fault diagnosis method provided by the invention is suitable for a two-stage intake VVL system based on an exhaust back pressure sensor, and is characterized in that whether the enabling condition of system fault diagnosis is met or not is judged according to the system state fed back by an engine control system, and if so, the maximum value and/or the minimum value of the corresponding actual exhaust back pressure value of each cylinder in the current lift of the engine in the exhaust stroke are obtained according to the measured voltage signals of the exhaust back pressure sensor and a crankshaft rotation speed sensor; then, according to the current exhaust flow of the engine, obtaining the maximum value and/or the minimum value of the expected exhaust back pressure value of each cylinder in the target lift; secondly, obtaining a lift switching preliminary diagnosis result of each cylinder according to the maximum value of the exhaust back pressure measured value of each cylinder corresponding to the current lift and the maximum value of the exhaust back pressure expected value corresponding to the target lift, and/or obtaining an exhaust back pressure preliminary diagnosis result of each cylinder at the current lift according to the minimum value of the exhaust back pressure measured value of each cylinder corresponding to the current lift and the minimum value of the exhaust back pressure expected value corresponding to the target lift; and if the preliminary diagnosis result of the exhaust back pressure is abnormal, obtaining a single or multiple cylinder lift switching diagnosis result according to the system state fed back by the engine control system. Therefore, the system fault diagnosis method provided by the invention obtains the maximum value and/or the minimum value of the exhaust back pressure actual measurement value corresponding to each cylinder in the current lift and the maximum value and/or the minimum value of the exhaust back pressure expected value corresponding to each cylinder in the target lift, and obtains the lift switching preliminary diagnosis result of each cylinder according to the maximum value and/or the minimum value of the exhaust back pressure actual measurement value and the minimum value of the exhaust back pressure expected value corresponding to each cylinder (for example, the maximum value and the maximum value of the exhaust back pressure expected value of each cylinder are compared), and when the lift switching fails, the maximum value and/or the minimum value of the exhaust back pressure expected value of the cylinder in the current lift can be different from the maximum value and/or the minimum value of the exhaust back pressure expected value of the cylinder in the target lift, so that whether the lift of each cylinder is abnormal or not can be judged according to the preliminary diagnosis result of each cylinder. Further, when the preliminary diagnosis result of the exhaust back pressure is that the exhaust back pressure is abnormal, the system fault diagnosis method provided by the invention can also obtain single or multiple cylinder lift switching diagnosis results (for example, the engine control system uses error lift switching information) according to the system state fed back by the engine control system, thereby laying a foundation for the subsequent timely switching to the corresponding fault post-treatment mode, and further guaranteeing the working stability of the engine.
Because the electronic device and the readable storage medium provided by the invention belong to the same inventive concept as the system fault diagnosis method provided by the invention, the electronic device and the readable storage medium have at least the same technical effects, and are not described in detail herein.
Drawings
FIG. 1 is a block diagram of a two-stage intake VVL system with an exhaust back pressure sensor according to one embodiment of the invention;
FIG. 2 is a flow chart of a system fault diagnosis method according to an embodiment of the present invention;
FIG. 3 is a graph showing the actual measurement of engine crank angle according to one embodiment of the present invention;
FIG. 4 is a partial measured graph of engine crank angle according to one embodiment of the present invention;
wherein, the reference numerals are as follows:
P 3 -an exhaust back pressure sensor.
Detailed Description
Specific embodiments of the present invention will be described in more detail below with reference to the drawings. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are in a very simplified form and are all to a non-precise scale, merely for convenience and clarity in aiding in the description of embodiments of the invention. It should be understood that the drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Specific design features of the invention disclosed herein, including for example, specific dimensions, orientations, positions, and configurations, will be determined in part by the specific intended application and use environment. In the embodiments described below, the same reference numerals are used in common between the drawings to denote the same parts or parts having the same functions, and the repetitive description thereof may be omitted. In this specification, like reference numerals and letters are used to designate like items, and thus once an item is defined in one drawing, no further discussion thereof is necessary in subsequent drawings.
Example 1
The present embodiment provides a tieReferring to fig. 1-2, fig. 1 schematically shows an exhaust back pressure sensor P according to the present embodiment 3 Fig. 2 schematically shows a flow of a system failure diagnosis method provided by the present embodiment. As can be seen from fig. 1 to fig. 2, the system fault diagnosis method provided in this embodiment is applicable to the exhaust back pressure sensor P 3 The two-stage intake VVL system of (2), the system failure diagnosis method includes:
s100: judging whether the enabling condition of system fault diagnosis is met according to the system state fed back by the engine control system, and if so, executing the following steps:
s200: according to exhaust back pressure sensor P 3 The measured voltage signal of the crankshaft rotation speed sensor is used for obtaining the maximum value and/or the minimum value of the corresponding measured exhaust back pressure value of each cylinder in the current lift in the exhaust stroke of the engine;
s300: obtaining the maximum value and/or the minimum value of the expected exhaust back pressure value of each cylinder in the target lift according to the current exhaust flow of the engine;
s400: obtaining a lift switching preliminary diagnosis result of each cylinder according to the maximum value of the exhaust back pressure measured value of each cylinder corresponding to the current lift and the maximum value of the exhaust back pressure expected value corresponding to the target lift, and/or obtaining an exhaust back pressure preliminary diagnosis result of each cylinder at the current lift according to the minimum value of the exhaust back pressure measured value of each cylinder corresponding to the current lift and the minimum value of the exhaust back pressure expected value corresponding to the target lift;
s500: and if the preliminary diagnosis result of the exhaust back pressure is abnormal, obtaining a single or multiple cylinder lift switching diagnosis result according to the system state fed back by the engine control system.
In this way, according to the system fault diagnosis method provided by the invention, the lift switching preliminary diagnosis result of each cylinder is obtained (for example, the maximum value and/or the minimum value of the corresponding actual exhaust back pressure value and the maximum value of the expected exhaust back pressure value of each cylinder are compared) by obtaining the maximum value and/or the minimum value of the corresponding actual exhaust back pressure value of each cylinder in the current lift and the maximum value and/or the minimum value of the corresponding expected exhaust back pressure value of each cylinder in the target lift, and as the maximum value and/or the minimum value of the corresponding actual exhaust back pressure value of each cylinder in the current lift are different from the maximum value and/or the minimum value of the expected exhaust back pressure value of each cylinder in the target lift, the abnormal back pressure of each cylinder corresponding to the preliminary diagnosis result of each cylinder can be determined according to the preliminary diagnosis result of each cylinder when the lift switching fails. Further, when the preliminary diagnosis result of the exhaust back pressure is that the exhaust back pressure is abnormal, the system fault diagnosis method provided by the invention can also obtain single or multiple cylinder lift switching diagnosis results (for example, the engine control system uses error lift switching information) according to the system state fed back by the engine control system, thereby laying a foundation for the subsequent timely switching to the corresponding fault post-treatment mode, and further guaranteeing the working stability of the engine.
Preferably, in step S100, the enabling conditions for system fault diagnosis include: the engine control system triggers the zone bit of the two-stage intake VVL system to switch, and the current engine speed reaches the preset speed and the exhaust back pressure sensor P 3 The electrical is normal. It should be noted that the enabling conditions include, but are not limited to: and the air inlet impulse corresponding to the current lift and the target lift reaches a preset condition, and the related detection signals in the engine control system are normal.
Referring to fig. 3 to 4, fig. 3 schematically shows an actual measurement diagram of the crank angle of the engine according to the present embodiment, and fig. 4 schematically shows a partial actual measurement diagram of the crank angle of the engine according to the present embodiment. As can be seen in connection with fig. 3-4, step S200 is described in terms of exhaustBack pressure sensor P 3 And the voltage signal measured by the crankshaft rotation speed sensor, the maximum value and/or the minimum value of the measured value of the exhaust back pressure corresponding to each cylinder in the current lift in the exhaust stroke of the engine are obtained, and the method comprises the following steps:
obtaining an actual measurement value of the exhaust back pressure of the engine crank angle at the current lift; obtaining the maximum value and/or the minimum value of the measured value of the exhaust back pressure of the engine crank angle in each crank angle interval;
and obtaining the maximum value and/or the minimum value of the exhaust back pressure measured value of each cylinder in the current lift according to the cylinder corresponding to each crank angle interval and the maximum value and/or the minimum value of the exhaust back pressure measured value in each crank angle interval.
Specifically, as it is not difficult to find out in fig. 3 and 4, since each of the cylinders is sequentially switched, the switching time is different, and the switching time of each of the cylinders corresponds to a crank angle interval. For convenience of explanation, a four-cylinder engine is taken as an example, and the crank angle of the engine is 720 ° and includes four crank angle intervals, wherein each 180 ° corresponds to one cylinder. Therefore, the maximum value and/or the minimum value of the exhaust back pressure measured value of each cylinder are obtained by obtaining the maximum value and/or the minimum value of the exhaust back pressure measured value of each crank angle of the engine in each crank angle interval.
In one preferred embodiment, the obtaining the preliminary diagnosis of the exhaust back pressure of each cylinder at the current lift includes:
calculating a difference value between a maximum value of the exhaust back pressure measured value corresponding to the current lift and a maximum value of the exhaust back pressure expected value corresponding to the target lift of each cylinder, and/or calculating a difference value between a minimum value of the exhaust back pressure measured value corresponding to the current lift and a minimum value of the exhaust back pressure expected value corresponding to the target lift of each cylinder;
comparing the difference of the maximum values of each cylinder with a first preset threshold value, and/or comparing the difference of the minimum values of each cylinder with the first preset threshold value;
and when the difference value of the maximum value of the current lift of the cylinder is larger than a first preset threshold value, or the difference value of the minimum value of the current lift of the cylinder is larger than the first preset threshold value, judging that the exhaust back pressure of the cylinder is abnormal.
Thus, the present embodiment compares the difference of the maximum value of each of the cylinders with a first preset threshold value, and/or compares the difference of the minimum value of each of the cylinders with the first preset threshold value; thereby determining whether the cylinder to which the comparison is made is abnormal in exhaust back pressure. Meanwhile, the difference value of each cylinder can be compared with the preset threshold value, so that the system fault diagnosis method provided by the embodiment realizes the exhaust back pressure diagnosis of a single cylinder or a part of cylinders in the engine.
In another preferred embodiment, the obtaining the preliminary diagnosis of the exhaust back pressure of each cylinder at the current lift includes:
comparing the maximum value of the measured exhaust back pressure values of all the cylinders at the current lift with each other and/or comparing the minimum value of the measured exhaust back pressure values of all the cylinders at the current lift with each other:
and if the difference between the maximum value of the measured exhaust back pressure value of one cylinder at the current lift and the maximum value of the measured exhaust back pressure value of each other cylinder at the current lift is larger than a second preset threshold value, or if the difference between the minimum value of the measured exhaust back pressure value of one cylinder at the current lift and the minimum value of the measured exhaust back pressure value of each other cylinder at the current lift is larger than the second preset threshold value, judging that the exhaust back pressure of the cylinder is abnormal.
Thus, the present embodiment further determines whether there is a problem of abnormality in the exhaust back pressure of a single or partial cylinder by comparing the maximum or minimum value of the actual exhaust back pressure value of each cylinder at the current lift with each other.
Preferably, if the preliminary diagnosis result of the exhaust back pressure is that the exhaust back pressure is abnormal, obtaining a single or multiple cylinder lift switching diagnosis result according to a system state fed back by the engine control system, including:
detecting whether an interference factor exists in the engine control system according to the system state fed back by the engine control system:
if so, judging that the exhaust back pressure of the cylinder is abnormal due to the interference factors;
if not, determining that the single or multiple cylinder lift switching failure causes the exhaust back pressure abnormality.
In one preferred embodiment, the preset interference factor includes: the cylinder is misfiring.
Thus, when a disturbance factor exists, the exhaust back pressure is considered to be abnormal due to the disturbance factor, and is not caused by lift switching failure; if no interference factor exists, it may be determined that the exhaust back pressure is abnormal due to failure of single or multiple cylinder lift switching, thereby determining the failure of single or multiple cylinder lift switching.
In one preferred embodiment, the determining that the disturbance factor causes the exhaust back pressure of the single or multiple cylinders to be abnormal includes:
acquiring the current lift and a target lift of the engine;
if the current lift of the engine is a small lift and the target lift is a large lift: acquiring an engine air-fuel ratio, and judging that the single or multiple cylinders are in fire so as to cause abnormal exhaust back pressure of the single or multiple cylinders when the engine air-fuel ratio is smaller than a preset air-fuel ratio value;
if the current lift of the engine is a large lift and the target lift is a small lift: acquiring the air-fuel ratio of the engine, and if the air-fuel ratio of the engine is smaller than a preset air-fuel ratio value; and acquiring an engine knock sensor signal, and judging that the exhaust back pressure is abnormal due to failure of switching of single or multiple cylinder lifts of the engine when the engine knock sensor signal is larger than a preset signal value.
According to the embodiment, a single or multiple cylinder lift switching diagnosis result can be obtained according to the system state fed back by the engine control system, so that a foundation is laid for the subsequent timely switching to the corresponding fault post-treatment mode, and the working stability of the engine is further ensured.
For ease of understanding, the present embodiment is described with respect to cylinder misfire and the engine control system using erroneous lift switching information: when the maximum value and the minimum value of the measured exhaust back pressure value of the cylinder in the exhaust stroke are abnormal due to the fact that a single or multiple cylinders of the engine are in fire, the air-fuel ratio of the system is over lean; when the two-step intake VVL system is switched from the small lift system to the large lift, if there is a failure in switching of the cylinder lift or cylinders, the system air-fuel ratio appears to be excessively rich. Therefore, during switching of the two-stage intake VVL system, the problem of exhaust back pressure abnormality caused by a cylinder misfire can be eliminated by the engine air-fuel ratio behavior. In addition, when the two-step intake VVL system is switched from the large lift to the small lift, the air-fuel ratio of the system is lean when the switching failure of the lift of the single or multiple cylinders occurs, but the engine control system uses the erroneous lift information to perform the charge ignition calculation, and the knocking phenomenon occurs in the cylinder in which the switching failure of the lift occurs. Therefore, when the two-step intake VVL system is switched from the large lift to the small lift, the abnormality of the exhaust back pressure caused by the cylinder misfire can be eliminated in conjunction with the engine knock sensor signal behavior.
More specifically, it has been found that the maximum and minimum values of the actual exhaust back pressure values achievable during a single cylinder exhaust stroke of the engine are primarily affected by the current exhaust flow. Preferably, in one exemplary embodiment, the exhaust flow rate may be calculated using the following formula:
wherein:
for exhaust flow, n Eng For the current rotational speed of the engine,/->
Conversion coefficient of charging efficiency and intake air flow rate related to rotation speed, m cyl，in For engine intake charge, k air/fuel Is an air-fuel ratio that is directly related to the excess air ratio and the air-fuel ratio.
Further, in the above formula, the engine intake charge is based on an ideal gas equation by taking gas in a cylinder as a research object, and according to the intake manifold pressure, the partial pressure of residual exhaust gas in the cylinder and the current charging slope, the engine intake charge can be calculated by the following formula:
m cyl，in ＝fac chrg ·(p intk -p res )
in the above, m cyl，in For engine intake charge, fac chrg Is the current inflation slope; p is p intk Is intake manifold pressure; p is p res Partial pressure of residual exhaust gas for the cylinder.
Further, due to the current inflation slope fac chrg Depending on the intake valve closing time (ivc) corresponding to the current two-stage intake VVL system, the current charge slope fac is preferably chrg The following formula is adopted for obtaining:
fac chrg ＝f(ivc)，
ivc＝agIntk meas +offset (Large/Small Lift)
Wherein ivc is the closing time of the intake valve; aglintk meas For the measured phase of the two-step intake VVL system, offset is the intake VVT wrap angle corresponding to the large/small lift.
By combining the above formulas, a desired value of the exhaust flow rate of each of the cylinders in the target lift can be obtained. Preferably, the following formula can be used for the acquisition:
wherein, the liquid crystal display device comprises a liquid crystal display device,
is the expected value of the exhaust flow of the cylinder of the engine, n Eng K is the current rotation speed of the engine air/fuel Is the air fuel coefficient, p intk For intake manifold pressure, ivc is the intake valve closing time.
The maximum value of the expected exhaust back pressure value of each cylinder in the target lift range is obtained by adopting the following formula:
wherein, the liquid crystal display device comprises a liquid crystal display device,
h is the maximum value of the expected exhaust back pressure under the current working condition 1 Is a fitted function of the maximum value of the expected value of the exhaust back pressure of the engine cylinder.
The minimum value of the expected exhaust back pressure value of each cylinder in the target lift range is obtained by adopting the following formula:
wherein, the liquid crystal display device comprises a liquid crystal display device,
is the minimum value of the expected exhaust back pressure value under the current working condition, h 2 Is a fitting function of the minimum of the expected values of the exhaust back pressure of the engine cylinders.
It should be noted that, as will be understood by those skilled in the art, the method of obtaining the maximum value and the minimum value of the expected exhaust back pressure value of each cylinder at the target lift according to the above calculation method is merely illustrative, and not limiting to the present invention, and when the system fault diagnosis method provided in this embodiment is implemented, those skilled in the art may also use other methods than the calculation method to obtain the maximum value and the minimum value of the expected exhaust back pressure value of each cylinder at the target lift.
Example two
The embodiment provides an electronic device, including a processor and a memory, where the memory stores a computer program, and when the computer program is executed by the processor, the system fault diagnosis method described in any one of the foregoing embodiments is implemented.
Because the electronic equipment and the system fault diagnosis method provided by the invention belong to the same invention conception, at least the same technical effects are achieved, and the details are not repeated here.
Example III
The present embodiment provides a readable storage medium having stored therein a computer program which, when executed by a processor, implements the system fault diagnosis method of any one of the above.
The readable storage media of embodiments of the present invention may take the form of any combination of one or more computer-readable media. The readable medium may be a computer readable signal medium or a computer readable storage medium. The computer readable storage medium can be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or a combination of any of the foregoing. More specific examples (a non-exhaustive list) of the computer-readable storage medium would include the following: an electrical connection having one or more wires, a portable computer hard disk, a hard disk, random Access Memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.
The computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, either in baseband or as part of a carrier wave. Such a propagated data signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination of the foregoing. A computer readable signal medium may also be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.
Computer program code for carrying out operations of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, smalltalk, C ++ and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any kind of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or may be connected to an external computer (for example, through the Internet using an Internet service provider).
In addition, the systems and methods disclosed in the embodiments herein may be implemented in other manners. The apparatus embodiments described above are merely illustrative, for example, flow diagrams and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods and computer program products according to various embodiments herein. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions. In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example.
In summary, according to the system fault diagnosis method provided by the invention, by obtaining the maximum value and/or the minimum value of the actual exhaust back pressure value corresponding to each cylinder in the current lift and the maximum value and/or the minimum value of the exhaust back pressure expected value corresponding to each cylinder in the target lift, and according to the maximum value and the maximum value of the actual exhaust back pressure value corresponding to each cylinder and/or the minimum value of the corresponding actual exhaust back pressure value and the minimum value of the exhaust back pressure expected value of each cylinder, a preliminary diagnosis result of lift switching of each cylinder (for example, comparing the maximum value and the maximum value of the actual exhaust back pressure value corresponding to each cylinder with the maximum value of the exhaust back pressure expected value of each cylinder) is obtained, and when the lift switching of each cylinder fails, the maximum value and/or the minimum value of the actual exhaust back pressure value of the cylinder in the current lift and the maximum value and/or the minimum value of the exhaust back pressure expected value of the cylinder in the target lift are different, so that whether the corresponding exhaust back pressure of each cylinder is abnormal or not can be judged according to the preliminary diagnosis result of each cylinder. Further, when the preliminary diagnosis result of the exhaust back pressure is that the exhaust back pressure is abnormal, the system fault diagnosis method provided by the invention can also obtain single or multiple cylinder lift switching diagnosis results (for example, the engine control system uses error lift switching information) according to the system state fed back by the engine control system, thereby laying a foundation for the subsequent timely switching to the corresponding fault post-treatment mode, and further guaranteeing the working stability of the engine.
Because the electronic device and the readable storage medium provided by the invention belong to the same inventive concept as the system fault diagnosis method provided by the invention, the electronic device and the readable storage medium have at least the same technical effects, and are not described in detail herein.
The foregoing is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art will make any equivalent substitution or modification to the technical solution and technical content disclosed in the invention without departing from the scope of the technical solution of the invention, and the technical solution of the invention is not departing from the scope of the invention.
Claims (10)
1. A system failure diagnosis method, which is applicable to a two-stage intake VVL system based on an exhaust back pressure sensor, comprising:
judging whether the enabling condition of system fault diagnosis is met according to the system state fed back by the engine control system, and if so, executing the following steps:
according to the measured voltage signals of the exhaust back pressure sensor and the crankshaft rotating speed sensor, obtaining the maximum value and/or the minimum value of the corresponding exhaust back pressure measured value of each cylinder of the current lift of the engine in the exhaust stroke;
obtaining the maximum value and/or the minimum value of the expected exhaust back pressure value of each cylinder in the target lift according to the current exhaust flow of the engine;
obtaining a lift switching preliminary diagnosis result of each cylinder according to the maximum value of the exhaust back pressure measured value of each cylinder corresponding to the current lift and the maximum value of the exhaust back pressure expected value corresponding to the target lift, and/or obtaining an exhaust back pressure preliminary diagnosis result of each cylinder at the current lift according to the minimum value of the exhaust back pressure measured value of each cylinder corresponding to the current lift and the minimum value of the exhaust back pressure expected value corresponding to the target lift;
and if the preliminary diagnosis result of the exhaust back pressure is abnormal, obtaining a single or multiple cylinder lift switching diagnosis result according to the system state fed back by the engine control system.
2. The system fault diagnosis method according to claim 1, wherein the enabling conditions for system fault diagnosis include:
and the engine control system triggers the zone bit of the switching of the two-stage intake VVL system, the current engine rotating speed reaches the preset rotating speed, and the exhaust back pressure sensor is electrically normal.
3. The system fault diagnosis method according to claim 1, wherein the step of obtaining the maximum and/or minimum value of the measured exhaust back pressure value of each cylinder of the current lift of the engine in the exhaust stroke according to the measured voltage signals of the exhaust back pressure sensor and the crankshaft rotation speed sensor comprises the steps of:
obtaining an actual measurement value of the exhaust back pressure of the engine crank angle at the current lift; obtaining the maximum value and/or the minimum value of the measured value of the exhaust back pressure of the engine crank angle in each crank angle interval;
and obtaining the maximum value and/or the minimum value of the exhaust back pressure measured value of each cylinder in the current lift according to the cylinder corresponding to each crank angle interval and the maximum value and/or the minimum value of the exhaust back pressure measured value in each crank angle interval.
4. The system fault diagnosis method according to claim 1, wherein said obtaining an exhaust back pressure preliminary diagnosis result for each of the cylinders at the current lift includes:
calculating a difference value between a maximum value of the exhaust back pressure measured value corresponding to the current lift and a maximum value of the exhaust back pressure expected value corresponding to the target lift of each cylinder, and/or calculating a difference value between a minimum value of the exhaust back pressure measured value corresponding to the current lift and a minimum value of the exhaust back pressure expected value corresponding to the target lift of each cylinder;
comparing the difference of the maximum values of each cylinder with a first preset threshold value, and/or comparing the difference of the minimum values of each cylinder with the first preset threshold value;
and when the difference value of the maximum value of the current lift of the cylinder is larger than a first preset threshold value, or the difference value of the minimum value of the current lift of the cylinder is larger than the first preset threshold value, judging that the exhaust back pressure of the cylinder is abnormal.
5. The system fault diagnosis method according to claim 1, wherein said obtaining an exhaust back pressure preliminary diagnosis result for each of the cylinders at the current lift includes:
comparing the maximum value of the exhaust back pressure measured value of all the cylinders at the current lift with each other and/or comparing the minimum value of the exhaust back pressure measured value of all the cylinders at the current lift with each other;
and if the difference between the maximum value of the measured exhaust back pressure value of one cylinder at the current lift and the maximum value of the measured exhaust back pressure value of each other cylinder at the current lift is larger than a second preset threshold value, or if the difference between the minimum value of the measured exhaust back pressure value of one cylinder at the current lift and the minimum value of the measured exhaust back pressure value of each other cylinder at the current lift is larger than the second preset threshold value, judging that the exhaust back pressure of the cylinder is abnormal.
6. The system fault diagnosis method according to claim 1, wherein if the preliminary diagnosis result of exhaust back pressure is abnormal, obtaining a single or multiple cylinder lift switching diagnosis result according to a system state fed back by the engine control system, including:
detecting whether an interference factor exists in the engine control system according to the system state fed back by the engine control system;
if the exhaust back pressure of the single or multiple cylinders is abnormal, judging that the interference factors cause the exhaust back pressure of the single or multiple cylinders;
if not, determining that the single or multiple cylinder lift switching failure causes the exhaust back pressure abnormality.
7. The system fault diagnosis method as claimed in claim 6, wherein the preset interference factor comprises: the cylinder is misfiring.
8. The system fault diagnosis method according to claim 7, wherein the determining that the disturbance factor causes abnormality in the single or multiple cylinder exhaust back pressure includes:
acquiring the current lift and a target lift of the engine;
if the current lift of the engine is a small lift and the target lift is a large lift: acquiring an engine air-fuel ratio, and judging that the single or multiple cylinders are in fire so as to cause abnormal exhaust back pressure of the single or multiple cylinders when the engine air-fuel ratio is smaller than a preset air-fuel ratio value;
if the current lift of the engine is a large lift and the target lift is a small lift: acquiring the air-fuel ratio of the engine, and if the air-fuel ratio of the engine is smaller than a preset air-fuel ratio value; and acquiring an engine knock sensor signal, and judging that the exhaust back pressure is abnormal due to failure of switching of single or multiple cylinder lifts of the engine when the engine knock sensor signal is larger than a preset signal value.
9. An electronic device comprising a processor and a memory, the memory having stored thereon a computer program which, when executed by the processor, implements the system fault diagnosis method of any of claims 1-8.
10. A readable storage medium, characterized in that the readable storage medium has stored therein a computer program which, when executed by a processor, implements the system fault diagnosis method of any one of claims 1-8.
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