CN112254970A - Rapid and accurate combustion noise separation method - Google Patents
Rapid and accurate combustion noise separation method Download PDFInfo
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- CN112254970A CN112254970A CN202011058716.9A CN202011058716A CN112254970A CN 112254970 A CN112254970 A CN 112254970A CN 202011058716 A CN202011058716 A CN 202011058716A CN 112254970 A CN112254970 A CN 112254970A
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- G—PHYSICS
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- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M15/00—Testing of engines
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- G—PHYSICS
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- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M15/00—Testing of engines
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Abstract
The invention discloses an accurate and rapid combustion noise separation method, which comprises the following steps: 1) according to the requirement of engine test, the engine is operated to a preset working condition, and the whole engine reaches a stable state; 2) after the whole engine reaches a stable state, monitoring the current temperature of the engine, controlling the engine to stop rotating and turning off the ignition function of the spark plug when the current temperature of the engine reaches the stable state; then making the engine suck a predetermined amount of mixture formed by air and gasoline under the non-ignition state; 3) after the step 2) is finished, the engine is in a heat engine state, single-cylinder ignition is carried out, and the transfer function of each single cylinder is measured in sequence; 4) and 3) obtaining the combustion noise under the real operation working condition according to the combustion noise transfer function and the cylinder pressure in the step 3). The method of the invention utilizes the combustible mixed gas introduced by the engine to carry out ignition, has longer duration and greatly improves the calculation precision of combustion noise.
Description
Technical Field
The invention relates to an engine test technology, in particular to a quick and accurate combustion noise separation method.
Background
In the engine radiation noise, a component related to the cylinder pressure is regarded as direct combustion noise, and the remaining noise not related to the cylinder pressure is regarded as mechanical noise. The mechanical noise can be further decomposed into anti-drag mechanical noise and load-related mechanical noise. The load-related mechanical noise is radiation noise caused by combustion pressure acting on the crank mechanism and transmitted to the engine to generate vibration and the like, such as piston knocking noise caused by a lateral knocking force of a piston against a cylinder liner.
In actual tests, the radiation noise contains combustion and mechanical sound at the same time, and the combustion noise cannot be completely separated from the radiation noise, namely, the combustion noise cannot be directly obtained through testing, so that the necessary separation method needs to be researched by combining means such as tests, and the combustion noise is quickly and accurately separated.
Disclosure of Invention
The invention aims to solve the technical problem of providing a quick and accurate combustion noise separation method aiming at the defects in the prior art.
The technical scheme adopted by the invention for solving the technical problems is as follows: a fast and accurate combustion noise separation method, comprising:
1) according to the requirement of engine test, the engine is operated to a preset working condition, and the whole engine reaches a stable state;
2) after the whole engine reaches a stable state, monitoring the current temperature of the engine, controlling the engine to stop rotating and turning off the ignition function of the spark plug when the current temperature of the engine reaches the stable state; then making the engine suck a predetermined amount of mixture formed by air and gasoline under the non-ignition state;
3) after the step 2) is finished, the engine is in a heat engine state, single-cylinder ignition is carried out, and the transfer function of each single cylinder is measured in sequence; the method comprises the following specific steps:
3.1) if the spark plug can not ignite the mixture gas by burning, returning to the step 2), and re-introducing the mixture gas in a non-ignition state;
3.2) sequentially finishing the ignition of each cylinder in turn, and synchronously measuring the cylinder pressure and the noise of the cylinder from the ignition moment to obtain a cylinder pressure curve and a noise curve of each single cylinder;
3.3) windowing the cylinder pressure obtained by testing to meet the resolution of the transfer function frequency; starting from the ignition moment, if tminAt time, P is greater than or equal to PminJudging that the data is valid, and entering the next step; otherwise, returning to the step 2);
wherein, tminFor intercepting the time period length of the cylinder pressure data, Pmin is the effective lower limit value of the cylinder pressure, and the cylinder pressure P is required to be more than PminTesting the effective cylinder pressure;
3.4) cylinder pressure and noise data without the influence of mechanical sound and load related noise are obtained, and accurate transfer functions H (f) of the cylinder pressure and the noise are obtained through calculation;
in the formula, Rv0pR is a cross-correlation function of cylinder pressure and noise signal, since the mechanical vibration transfer function is independent of cylinder pressurev0p＝Rvp,RvpAs a function of the cross-correlation of the cylinder pressure with the noise signal, RppIs an autocorrelation function of cylinder pressure;
4) according to the combustion noise transfer function and the cylinder pressure in the step 3), the combustion noise under the real operation working condition can be obtained; mechanical noise can be obtained according to the anti-drag noise, and the mechanical noise related to the load can be obtained by subtracting the combustion noise and the mechanical noise from the total noise; the anti-drag noise is generated when the engine is in an anti-drag state and is obtained through testing.
According to the scheme, the engine in the step 3) is in a heat engine state, single-cylinder ignition is carried out, and the method specifically comprises the following steps: and in the heat engine state, the crankshaft position is adjusted, and after each cylinder of the engine is respectively adjusted to 1 cylinder top dead center, the single cylinder is ignited.
According to the scheme, the preset working condition of the step 1) for operating the engine to the preset working condition is determined according to the required rotating speed and the required load.
The invention has the following beneficial effects:
1. the mixed gas entering the engine under the condition of non-ignition is used for ignition, so that a complex device for introducing combustible gas from the outside is avoided, and the operation is simple and easy.
2. The engine is tested when running to the concerned working condition, so that the accurate combustion noise transfer function under any working condition can be obtained, and great convenience and favorable conditions are provided for further researching the difference of the combustion noise transfer function under different working conditions.
3. The combustible mixed gas introduced by the engine is used for ignition, the duration is longer, more effective cylinder pressure and noise test data can be obtained, and the calculation precision of the transfer function is greatly improved.
4. When a certain cylinder runs to the top dead center of the piston, the mixed gas is ignited to carry out synchronous testing on the cylinder pressure and the noise. In this case, only the cylinder pressure acting force of combustion is generated, and there is no disturbance such as mechanical noise and piston knocking, and the combustion noise can be separated more accurately and purely than in the conventional method.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a flow chart of a method of an embodiment of the present invention;
FIG. 2 is a schematic representation of a cylinder pressure curve of an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
As shown in fig. 1, a fast and accurate combustion noise separation method includes the steps of:
(1) firstly, in the environment of an engine anechoic chamber, the engine is operated to a preset concerned working condition, such as a required rotating speed and a required load, and the whole engine is in a stable state. The parameters measured under the working condition can more truly represent the actual using working condition of the engine.
(2) After the engine reaches a stable state, the current temperature of the engine is relatively fixed, the engine is immediately controlled to stop running, the ignition function of the spark plug is closed, and a certain amount of air and gasoline are sucked into a mixed gas in a non-ignition state.
(3) In the heat engine state, the crankshaft position is adjusted, and after each cylinder of the engine is respectively adjusted to the upper dead point of 1 cylinder, the single cylinder is ignited; that is, after step (2) is completed, the engine is in a heat engine state, and the transfer function of each single cylinder needs to be measured in turn, so the test is performed from the first cylinder; the purpose of adjusting each single cylinder to the top dead center is only for convenient operation of an operator, and the crankshaft position is adjusted to be 30 degrees before and after the top dead center, so that the influence on the measurement effect is small.
(4) Generally, under the condition of forced ignition, the combustion duration is greatly prolonged, and the requirement of transfer function sampling precision is met. And after the ignition is successful, synchronously (simultaneously acquiring a cylinder pressure curve and a noise curve by a detection instrument) testing the cylinder pressure, the noise and the ignition signal.
(5) And (4) if the mixture cannot be ignited by the spark plug combustion, returning to the previous step, re-introducing the mixture under the non-ignition condition, and returning to the step (2).
(6) And (4) sequentially finishing ignition of top dead centers of the cylinders in turn from the step 4, and synchronously measuring the cylinder pressure and the noise of the cylinders to obtain cylinder pressure curves and noise curves of the single cylinders.
(7) Windowing the cylinder pressure obtained by testing, and if the interval is less than fs, t is required to ensure sufficient resolution of the transfer function frequencyminMore than 1/fs, cylinder pressure P is required to be more than P in order to ensure that the cylinder pressure meets certain excitationmin. Starting from the ignition moment, if tminAt time, P is greater than or equal to PminIf the data is valid, entering the next step; otherwise, returning to the step 2.
As shown in FIG. 2, tminAnd windowing the cylinder pressure obtained in the testing time period for intercepting the cylinder pressure data. In order to satisfy a certain excitation of the cylinder pressure, a lower limit value P is set for which the cylinder pressure is effectiveminCylinder pressure P > PminAnd the testing cylinder pressure is effective and can be used for intercepting section analysis.
(8) At the moment, pure cylinder pressure and noise data without the influence of mechanical sound, load-related noise and the like can be obtained, and accurate transfer functions of the cylinder pressure and the noise are obtained through calculation;
in the formula Rv0pIn which R is a cross-correlation function of cylinder pressure and noise signal, since the mechanical vibration transfer function is independent of cylinder pressurev0p＝ Rvp,RvpAs a function of the cross-correlation of cylinder pressure with noise signal, RppThe transfer function from detonation pressure to noise can be obtained as the autocorrelation function of the cylinder pressure.
Through the operation of single-cylinder ignition, the impact sound of the engine piston can be avoided; the spark plug is used for forced ignition, so that the combustion duration is greatly prolonged, the mixed gas can be fully combusted, the sampling precision is improved, and an accurate transfer function can be obtained.
(8) The engine normally runs under a specified working condition, and cylinder pressure and noise data (total noise) under the working condition are synchronously measured.
(9) The combustion noise under the real operation working condition can be obtained by multiplying the accurate combustion noise transfer function obtained by the calculation by the cylinder pressure, the mechanical noise can be obtained by the anti-dragging noise, and the mechanical noise related to the load can be obtained by subtracting the combustion noise and the mechanical noise from the total noise; the anti-drag noise is generated when the engine is in an anti-drag state and can be obtained through testing.
It will be understood that modifications and variations can be made by persons skilled in the art in light of the above teachings and all such modifications and variations are intended to be included within the scope of the invention as defined in the appended claims.
Claims (5)
1. A method for fast and accurate combustion noise separation, comprising:
1) according to the requirement of engine test, the engine is operated to a preset working condition, and the whole engine reaches a stable state;
2) after the whole engine reaches a stable state, monitoring the current temperature of the engine, controlling the engine to stop rotating and turning off the ignition function of the spark plug when the current temperature of the engine reaches the stable state; then making the engine suck a predetermined amount of mixture formed by air and gasoline under the non-ignition state;
3) after the step 2) is finished, the engine is in a heat engine state, single-cylinder ignition is carried out, and the transfer function of each single cylinder is measured in sequence;
4) according to the combustion noise transfer function and the cylinder pressure in the step 3), the combustion noise under the real operation working condition can be obtained; mechanical noise can be obtained according to the anti-drag noise, and the mechanical noise related to the load can be obtained by subtracting the combustion noise and the mechanical noise from the total noise; the anti-drag noise is generated when the engine is in an anti-drag state and is obtained through testing.
2. The combustion noise separation method as claimed in claim 1, wherein the step 3) measures the transfer function of each single cylinder in turn; the method comprises the following specific steps:
3.1) if the spark plug can not ignite the mixture gas by burning, returning to the step 2), and re-introducing the mixture gas in a non-ignition state;
3.2) sequentially finishing the ignition of each cylinder in turn, and synchronously measuring the cylinder pressure and the noise of the cylinder from the ignition moment to obtain a cylinder pressure curve and a noise curve of each single cylinder;
3.3) windowing the cylinder pressure obtained by testing to meet the resolution of the transfer function frequency; starting from the ignition moment, if tminAt time, P is greater than or equal to PminJudging that the data is valid, and entering the next step; otherwise, returning to the step 2);
wherein, tminFor intercepting the time period length of the cylinder pressure data, Pmin is the effective lower limit value of the cylinder pressure, and the cylinder pressure P is required to be more than PminTesting the effective cylinder pressure;
and 3.4) obtaining cylinder pressure and noise data under the condition of no mechanical sound and load related noise influence, and calculating to obtain a transfer function H (f) of the cylinder pressure and the noise.
3. The combustion noise separation method according to claim 2, wherein in step 3.4), the transfer function h (f) is calculated by using the following formula:
in the formula, Rv0pR is a cross-correlation function of cylinder pressure and noise signal, since the mechanical vibration transfer function is independent of cylinder pressurev0p＝Rvp,RvpAs a function of the cross-correlation of the cylinder pressure with the noise signal, RppIs an autocorrelation function of cylinder pressure.
4. The combustion noise separation method according to claim 1, wherein the engine in step 3) is in a heat engine state, and single-cylinder ignition is performed, specifically: and in the heat engine state, the crankshaft position is adjusted, and after each cylinder of the engine is respectively adjusted to 1 cylinder top dead center, the single cylinder is ignited.
5. The combustion noise separation method as claimed in claim 1, wherein the predetermined condition in the step 1) of operating the engine to the predetermined condition is determined based on the required speed and the required load.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113704879A (en) * | 2021-08-05 | 2021-11-26 | 重庆长安汽车股份有限公司 | Visualized correlation analysis method for engine radiation noise and combustion excitation |
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| CN110502824A (en) * | 2019-08-19 | 2019-11-26 | 武汉理工大学 | A kind of combustion noise fast separating process |
| CN211144657U (en) * | 2019-10-22 | 2020-07-31 | 南京林业大学 | Pulsation combustion engine capable of effectively reducing air intake noise |
| CN111487063A (en) * | 2020-03-20 | 2020-08-04 | 天津大学 | Parameter adaptive internal combustion engine noise source separation method |
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Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1233313A (en) * | 1996-08-23 | 1999-10-27 | 卡明斯发动机公司 | Premixed charge compression ignition engine with optimal combustion control |
| CN103670759A (en) * | 2012-08-29 | 2014-03-26 | 马自达汽车株式会社 | Spark-ignition direct injection engine |
| CN102901887A (en) * | 2012-09-04 | 2013-01-30 | 中国人民解放军济南军区军械雷达修理所 | Portable comprehensive detection diagnosis device and method for mobile power station |
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| CN111487063A (en) * | 2020-03-20 | 2020-08-04 | 天津大学 | Parameter adaptive internal combustion engine noise source separation method |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113704879A (en) * | 2021-08-05 | 2021-11-26 | 重庆长安汽车股份有限公司 | Visualized correlation analysis method for engine radiation noise and combustion excitation |
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