WO2020000913A1

WO2020000913A1 - Method and device for detecting engine misfire

Info

Publication number: WO2020000913A1
Application number: PCT/CN2018/120217
Authority: WO
Inventors: 宋国梁; 刘兴义; 曹石
Original assignee: 潍柴动力股份有限公司
Priority date: 2018-06-28
Filing date: 2018-12-11
Publication date: 2020-01-02
Also published as: CN109030009A

Abstract

A method and device for detecting an engine misfire, the method comprising: acquiring an original rotating speed signal of one work cycle of an engine in real time by means of a crankshaft signal sensor of the engine (S101); performing Fourier transform on the original rotating speed signal of one work cycle of the engine to obtain a primary harmonic amplitude and a primary harmonic phase (S102); and making a misfire determination by using the primary harmonic amplitude and the primary harmonic phase as characteristic signals (S103). By acquiring the original speed signal of the engine in real time, the engine is analyzed as a whole, and the phase and amplitude of the primary harmonic are used to determine whether a misfire occurs during engine operation, thereby avoiding damage to the engine and related components and worsening of emissions.

Description

Method and device for detecting engine misfire

This application claims priority from a domestic application filed with the Chinese Patent Office on June 28, 2018, with application number 201810686156.8, and the invention name is "A Method and Device for Engine Misfire Detection", the entire contents of which are incorporated herein by reference. Applying.

Technical field

The invention relates to the technical field of engine detection, and in particular, to a method and a device for detecting engine misfire.

Background technique

In the prior art, for engine misfire detection, the engine speed is collected to determine the rotational speed acceleration of each cylinder during the power stroke stage or the acceleration between the corresponding cylinders as the characteristic value of the misfire, and the characteristic value is compared with the threshold value to determine the engine corresponding. Whether the cylinder is misfired. When a cylinder misfires, the misfire cylinder is in the power stroke phase, the acceleration will be reduced compared to the cylinder without misfire, and the average speed of the power stroke phase corresponding to the misfire cylinder will also be smaller, resulting in the misfire cylinder and non-fire The acceleration between the cylinders becomes larger. Therefore, misfire detection is performed by judging the acceleration of the power stroke stage of each cylinder, which requires high engine speed and load. When the engine is operating normally, the fluctuation of the rotational speed is represented by the change of the angular momentum of the engine, and at low load, the change of the angular momentum caused by the combustion work is weak. Therefore, when the misfire occurs, the corresponding change in the engine speed is not obvious, and it is difficult to distinguish whether a misfire occurs; At the same time, as the rotational speed increases, the angular momentum of the engine increases quadratically with the rotational speed. With the same work done by each cylinder, the angular momentum fluctuations are relatively reduced, and the speed acceleration is not obvious when a misfire occurs.

Under the above circumstances, misfire detection is performed by using the acceleration of each cylinder in the power stroke stage, which is prone to misjudgment and cannot be accurately detected. Therefore, misfire detection needs to be performed in a limited load and speed range, that is, by determining the Acceleration for misfire diagnosis, there will be a large chance that the misfire cylinder will not be judged correctly. When no misfire occurs, the working consistency of each cylinder of the engine is high, and the acceleration between the cylinders is small. When a misfire occurs, the overall operating balance of the engine is broken because one or several cylinders do not work. As a result, the engine speed fluctuates in one working cycle, at which time the acceleration between the corresponding cylinders of the engine will increase. When the engine misfires under different speeds and loads, the speed fluctuations are inconsistent. The engine speed corresponding to the power stroke of the misfire cylinder may not be immediately reduced. Therefore, it is impossible to correctly determine which cylinder misfires.

Summary of the invention

The purpose of the present invention is to provide a method and a device for detecting a misfire in an engine, so as to accurately detect the occurrence rate of misfire in the engine and locate the specific misfire cylinder, thereby avoiding damage to the engine and related components due to the misfire of the engine and deterioration of emissions .

To achieve the above object, the present invention provides the following technical solutions:

A method for detecting a misfire in an engine includes:

The engine's crankshaft signal sensor collects the original speed signal of the engine in one working cycle in real time;

Fourier transform the original speed signal of one working cycle of the engine to obtain the first harmonic amplitude and the first harmonic phase;

Misfire determination is performed using the first harmonic amplitude and the first harmonic phase as characteristic signals.

Further, the step of determining a misfire using the first harmonic amplitude and the first harmonic phase as characteristic signals includes:

Determining whether there is a misfire and the number of misfire cylinders according to the amplitude of the first harmonic;

The misfire cylinder number is determined according to the first harmonic phase.

Further, the step of determining whether there is a misfire and the number of misfire cylinders according to the amplitude of the first harmonic includes:

Determining whether the amplitude of the first harmonic is within a preset threshold range;

If yes, it is determined to be misfired, and the number of misfired cylinders is determined according to the preset threshold range;

If not, it is determined that there is no fire.

Further, the step of determining a misfire cylinder number according to the first harmonic phase includes:

Query a preset phase list according to the first harmonic phase to determine the misfire cylinder number, and the preset phase list includes a first harmonic phase, the number of misfire cylinders and the misfire cylinder number, and a corresponding relationship among the three.

A device for detecting a misfire in an engine includes:

A first processing unit, configured to collect, in real time, an original speed signal of a working cycle of an engine through a crankshaft signal sensor of the engine;

A second processing unit, configured to perform a Fourier transform on the original speed signal of one working cycle of the engine to obtain a first harmonic amplitude and a first harmonic phase;

A third processing unit is configured to perform misfire judgment by using the first harmonic amplitude and the first harmonic phase as characteristic signals.

Further, the third processing unit includes:

A first determining unit, configured to determine whether there is a misfire and the number of misfire cylinders according to the amplitude of the first harmonic;

A second determining unit is configured to determine a misfire cylinder number according to the first harmonic phase.

Further, the first determining unit is configured to:

If not, it is determined that there is no fire.

Further, the second determining unit is configured to:

It can be known from the foregoing technical solutions that compared with the prior art, the present invention discloses a method and a device for detecting a misfire in an engine. The method includes: collecting an engine's crankshaft signal sensor in real time to collect the original speed signal of a working cycle of the engine; Fourier transform the original speed signal of one working cycle of the engine to obtain the first harmonic amplitude and the first harmonic phase; and use the first harmonic amplitude and the first harmonic phase as the characteristic signals to perform misfire judgment . The invention collects the engine's original speed signal in real time, analyzes the engine as a whole, and determines whether there is a misfire in the operation of the engine through the phase and amplitude of the first harmonic, thereby avoiding damage to the engine and related components and deterioration of emissions.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly explain the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely It is an embodiment of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without paying creative labor.

FIG. 1 is a flowchart of a method for detecting a misfire in an engine according to an embodiment of the present invention;

2 is a flowchart of a specific implementation manner of step S103 provided by an embodiment of the present invention;

3 is a test verification result of a first harmonic amplitude in an engine misfire detection provided by an embodiment of the present invention;

4 is a test verification result of a first harmonic phase in an engine misfire detection provided by an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of an engine misfire detection device according to an embodiment of the present invention.

detailed description

In the following, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

As shown in FIG. 1, an embodiment of the present invention provides a method for detecting a misfire in an engine. The method specifically includes the following steps:

S101. The engine's crankshaft signal sensor collects the original speed signal of the engine in one working cycle in real time.

In the embodiment of the present invention, the engine is analyzed as a whole, and the original speed signal of the engine is collected in real time through the crankshaft signal sensor of the engine, and the original speed signal of one working cycle is collected.

It should be noted that if the speed signal is not processed, the time of each tooth detected by the original crankshaft sensor can also be processed. After the same subsequent processing, a misfire can be determined, and the engine speed signal is calculated by detecting the time of the tooth. Real-time engine speed.

S102. Fourier transform the original speed signal of one working cycle of the engine to obtain a first harmonic amplitude and a first harmonic phase.

In the embodiment of the present invention, the first harmonic amplitude and the first harmonic phase are obtained by performing a Fourier transform on the original rotation speed signal of one working cycle.

S103. Use the first harmonic amplitude and the first harmonic phase as characteristic signals to perform misfire judgment.

As shown in FIG. 2, a specific implementation manner of step S103 provided by an embodiment of the present invention. Specifically, the step of determining a misfire by using a sequential harmonic amplitude and a first harmonic phase as a characteristic signal may specifically include the following steps:

S201. Determine whether there is a misfire and the number of misfire cylinders according to the amplitude of the first harmonic.

Specifically, the step of determining whether there is a misfire and the number of misfire cylinders according to the amplitude of the first harmonic includes:

If not, it is determined that there is no fire.

It should be noted that, as shown in Fig. 3, the test results of the amplitude of the first harmonic are verified. When there is no misfire, the amplitude of the phase of the first harmonic is small. When the misfire occurs, the amplitude of the first harmonic becomes large. And the more the number of misfire cylinders, the larger the amplitude change under the same conditions.

S202. Determine a misfire cylinder number according to the first harmonic phase.

When it is determined that there is a misfire and the number of misfired cylinders is determined, the misfired cylinder number is determined according to the first harmonic phase. Specifically, the step of determining the misfired cylinder number according to the first harmonic phase includes:

It should be noted that, as shown in FIG. 4, in order to verify the results of the first harmonic phase test, the number of misfire cylinders is different and the first harmonic phase is different under the same working condition, and the misfire cylinder number can be indirectly known.

An embodiment of the present invention provides a method for detecting a misfire in an engine. The method includes: collecting, in real time, an original rotational speed signal of one working cycle of an engine through a crankshaft signal sensor of the engine; The leaf transformation obtains the first harmonic amplitude and the first harmonic phase; and uses the first harmonic amplitude and the first harmonic phase as characteristic signals to perform misfire judgment. The invention collects the engine's original speed signal in real time, analyzes the engine as a whole, and determines whether there is a misfire in the operation of the engine through the phase and amplitude of the first harmonic to avoid engine and related component damage and emissions deterioration.

The method is described in detail in the above-mentioned disclosed embodiments of the present invention, and the method of the present invention can be implemented by using various forms of devices. Therefore, the present invention also discloses a device, and specific examples are given below for detailed description.

As shown in FIG. 5, an embodiment of the present invention provides a device for detecting an engine misfire. The device specifically includes: a first processing unit 501, a second processing unit 502, and a third processing unit 503, where:

A first processing unit 501, configured to collect, in real time, an original speed signal of a working cycle of an engine through a crankshaft signal sensor of the engine;

A second processing unit 502, configured to perform a Fourier transform on the original speed signal of one working cycle of the engine to obtain a first harmonic amplitude and a first harmonic phase;

The third processing unit 503 is configured to perform misfire judgment by using the first harmonic amplitude and the first harmonic phase as characteristic signals.

Further, the third processing unit 503 may include:

A first determining unit 5031, configured to determine whether there is a misfire and the number of misfire cylinders according to the amplitude of the first harmonic;

A second determining unit 5032 is configured to determine a misfire cylinder number according to the first harmonic phase.

Further, the first determining unit 501 is configured to:

If not, it is determined that there is no fire.

Further, the second determining unit 502 is configured to:

An embodiment of the present invention provides a device for detecting a misfire in an engine. The present invention collects an engine's original speed signal in real time, analyzes the engine as a whole, and determines whether there is a misfire in the engine operation through the phase and amplitude of the first harmonic. Avoid damage to engines and related components and worsening emissions.

It should be noted that in this article, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that these entities or operations There is any such actual relationship or order among them. Moreover, the terms "including," "including," or any other variation thereof are intended to encompass non-exclusive inclusion, such that an item or device that includes a series of elements includes not only those elements, but also other elements that are not explicitly listed, Or it may include elements inherent to such an article or device. Without more restrictions, the elements defined by the sentence "including one ..." do not exclude the existence of other identical elements in articles or equipment including the above-mentioned elements.

The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but shall conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

A method for detecting a misfire in an engine, comprising:

The engine's crankshaft signal sensor collects the original speed signal of the engine in one working cycle in real time;

Fourier transform the original speed signal of one working cycle of the engine to obtain the first harmonic amplitude and the first harmonic phase;

Misfire determination is performed using the first harmonic amplitude and the first harmonic phase as characteristic signals.
The method according to claim 1, wherein the step of determining a misfire using the first harmonic amplitude and the first harmonic phase as characteristic signals comprises:

Determining whether there is a misfire and the number of misfire cylinders according to the amplitude of the first harmonic;

The misfire cylinder number is determined according to the first harmonic phase.
The method according to claim 2, wherein the step of determining whether there is a misfire and the number of misfire cylinders according to the amplitude of the first harmonic includes:

Determining whether the amplitude of the first harmonic is within a preset threshold range;

If yes, it is determined to be misfired, and the number of misfired cylinders is determined according to the preset threshold range;

If not, it is determined that there is no fire.
The method according to claim 2, wherein the step of determining the misfire cylinder number according to the first harmonic phase includes:

Query a preset phase list according to the first harmonic phase to determine the misfire cylinder number, and the preset phase list includes a first harmonic phase, the number of misfire cylinders and the misfire cylinder number, and a corresponding relationship among the three.
A device for detecting a misfire in an engine, comprising:

A first processing unit, configured to collect, in real time, an original speed signal of a working cycle of an engine through a crankshaft signal sensor of the engine;

A second processing unit, configured to perform a Fourier transform on the original speed signal of one working cycle of the engine to obtain a first harmonic amplitude and a first harmonic phase;

A third processing unit is configured to perform misfire judgment by using the first harmonic amplitude and the first harmonic phase as characteristic signals.
The apparatus according to claim 5, wherein the third processing unit comprises:

A first determining unit, configured to determine whether there is a misfire and the number of misfire cylinders according to the amplitude of the first harmonic;

A second determining unit is configured to determine a misfire cylinder number according to the first harmonic phase.
The apparatus according to claim 6, wherein the first determining unit is configured to:

Determining whether the amplitude of the first harmonic is within a preset threshold range;

If yes, it is determined to be misfired, and the number of misfired cylinders is determined according to the preset threshold range;

If not, it is determined that there is no fire.
The apparatus according to claim 6, wherein the second determining unit is configured to:

Query a preset phase list according to the first harmonic phase to determine the misfire cylinder number, and the preset phase list includes a first harmonic phase, the number of misfire cylinders and the misfire cylinder number, and a corresponding relationship among the three.