CN111780866A - Diesel engine test base installation state natural frequency testing method and device - Google Patents
Diesel engine test base installation state natural frequency testing method and device Download PDFInfo
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- CN111780866A CN111780866A CN202010606654.4A CN202010606654A CN111780866A CN 111780866 A CN111780866 A CN 111780866A CN 202010606654 A CN202010606654 A CN 202010606654A CN 111780866 A CN111780866 A CN 111780866A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H17/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves, not provided for in the preceding groups
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
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- Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)
Abstract
In order to solve the problem of inaccurate test result of the natural frequency of the diesel engine test base in the prior art, the invention provides a method and a device for testing the natural frequency of the installation state of the diesel engine test base, which are characterized in that: the method comprises the following steps: s1, collecting a vibration time domain signal of a test base and the rotating speed of a diesel engine; s2, carrying out Fourier transform on the vibration time domain signal in the step S1, and converting the vibration time domain signal into a vibration frequency domain signal; s3, obtaining a frequency spectrum curve with the abscissa as frequency and the ordinate as vibration amplitude; and S4, sequentially analyzing the frequency spectrum curves obtained in the step S3 according to a spectrogram analysis method and an order slice image analysis method to obtain a certain order natural frequency of the test base. The natural frequency of the test base is measured in the installation state, the natural frequency of the diesel engine base is collected and analyzed through excitation generated by the diesel engine, and a certain order of natural frequency of the test base can be quickly and accurately obtained.
Description
Technical Field
The invention relates to the field of high-speed diesel engine tests, in particular to a method and a device for testing natural frequency of a diesel engine test base in a mounting state.
Background
According to a traditional testing means of the natural frequency of the oil engine test base in the installation state, such as a hammering method, because the base in the installation state is too solid, an effective frequency response curve is hardly excited, and the natural frequency is difficult to separate and capture.
The conventional process for testing the natural frequency of the existing diesel engine test base is as follows: firstly, carrying out free state modal test, and obtaining the natural frequency and the vibration mode of the base by a test means; then comparing the test result with the simulation calculation result, adjusting the model, and enabling the model state to be close to the actual measurement state as much as possible; and finally, establishing a boundary constraint state in simulation software, simulating a test installation state, and performing simulation calculation in the installation state. However, the simulation model often cannot be in the same boundary state as the actual installation, and the accuracy of the simulation result is not high.
Disclosure of Invention
In order to solve the problem that the natural frequency test result of the diesel engine test base in the prior art is inaccurate, the invention provides the method and the device for testing the natural frequency of the diesel engine test base in the installation state.
The natural frequency testing method for the mounting state of the diesel engine test base is characterized by comprising the following steps of: the method comprises the following steps:
s1, mounting a diesel engine on a test base, and collecting a vibration time domain signal of the test base and the rotating speed of the diesel engine;
s2, setting different rotating speed grades according to the rotating speed grade of the diesel engine, taking the rotating speed grades as a calculation period, and carrying out Fourier transform on the vibration time domain signal in the step S1 to convert the vibration time domain signal into a vibration frequency domain signal;
s3, placing the vibration frequency domain signal corresponding to each rotating speed gear in the step S2 into a coordinate system to obtain a frequency spectrum curve with the abscissa as frequency and the ordinate as vibration amplitude;
and S4, sequentially analyzing the frequency spectrum curves obtained in the step S3 according to a frequency spectrum graph analysis method and an order slice graph analysis method, and averaging the results to obtain a certain order natural frequency of the test base.
The utility model provides a diesel engine test base installation state natural frequency testing arrangement which characterized in that: the device comprises a PC end, a signal acquisition instrument, a vibration acceleration sensor arranged on a diesel engine test base and a rotating speed sensor used for detecting the rotating speed of the diesel engine; the PC end is electrically connected with the signal acquisition instrument and is used for acquiring data of the signal acquisition instrument; the signal acquisition instrument is respectively connected with the vibration acceleration sensor and the rotating speed sensor in an electric mode and is used for acquiring the vibration acceleration of the diesel engine test base and the rotating speed of the diesel engine.
Has the advantages that: the invention uses the self-working exciting force of the diesel engine to excite the test base in a wider frequency range, when the frequency of the exciting force is close to a certain order natural frequency in the base installation state, the base can generate larger vibration, which reflects that a larger amplitude appears at a certain position on a vibration signal, thereby obtaining the certain order natural frequency of the test base.
The natural frequency of the test base is measured in the installation state, the natural frequency of the diesel engine base is collected and analyzed through excitation generated by the diesel engine, and a certain order of natural frequency of the test base can be quickly and accurately obtained.
Drawings
FIG. 1 is a flow chart of the method of the present invention.
FIG. 2 is a diagram of a test system according to the present invention.
Fig. 3 is a graph of a natural frequency test spectrum.
FIG. 4 is a 1.5 order slice.
Fig. 5 is a 2.0 order slice.
FIG. 6 is a 2.5 order slice.
FIG. 7 is a 3.5 order slice.
Wherein, 1 is the PC end, 2 is the communication net twine, 3 is signal acquisition appearance, 4 is a set of vibration acceleration sensor, 5 is experimental base, 6 is speed sensor, 7 is the signal line.
Detailed Description
The invention is described in further detail below with reference to the figures and the examples. It should be understood that the specific embodiments described herein are illustrative of the invention and are not limiting of the scope of the invention.
Specific example I: the PC terminal 1 may be a notebook computer.
As shown in figure 2, the natural frequency testing device for the installation state of the diesel engine test base comprises a notebook computer, and is in communication connection with a signal acquisition instrument 3 through a communication network cable 2, the signal acquisition instrument 3 is connected with a rotating speed sensor 6 and a set of vibration acceleration sensor 4 through a signal cable 7, the rotating speed sensor 6 is installed near a fluted disc for measuring the rotating speed of the diesel engine, the vibration acceleration sensor 4 is arranged on the diesel engine test base 5, and the rotating speed and vibration signals are displayed on the notebook computer 1 in real time.
As shown in fig. 1, the method for testing the natural frequency of the diesel engine test base in the installation state is characterized in that: the method comprises the following steps:
s1, under the no-load state of the diesel engine, in a working rotating speed range, such as a rotating speed range from idling to the highest rotating speed, through continuous rising/falling of the rotating speed, a vibration acceleration sensor 4 installed on a test base 5 records the vibration state of the test base 5 to a notebook computer through a signal acquisition instrument 3 in real time.
And S2, setting the rotating speed grade by taking the rotating speed measured by the rotating speed sensor 6 as a trigger signal, and performing Fourier transform on the vibration time domain signal acquired by the vibration acceleration sensor 4 by taking the specific rotating speed grade as a calculation period to convert the vibration time domain signal into a vibration signal in a frequency domain, namely a time domain signal.
And S3, in the working rotating speed range in the step S2, putting the vibration frequency domain signals acquired by each rotating speed gear and obtained by Fourier transform into a coordinate system, and uniformly displaying. In the spectrum curve, the abscissa is frequency, the ordinate is vibration amplitude, the amplitude of the curve represents the magnitude of the vibration velocity, and the larger the vibration velocity, the higher the amplitude.
S4, sequentially analyzing the spectrum curves in the step S3 according to a spectrogram analysis method and an order slice image analysis method: there are two methods for analyzing test data:
one is a spectrogram analysis method, as shown in fig. 3, when a significantly more concentrated peak appears near a certain frequency in a spectrogram, it is considered that a certain order natural frequency of the test base 5 exists there;
second, the order slice analysis method is, as shown in fig. 4 to 7, a plurality of order slices are taken, the peaks are collected, and when the frequencies corresponding to the peaks are concentrated near a certain frequency, the frequency is regarded as a certain order natural frequency of the test base 5, as shown in table I. Comparing the natural frequencies obtained by the two methods can more accurately obtain the natural frequency of the test base, as shown in Table II. Preferably, an averaging algorithm may be used to obtain a certain order natural frequency of the final test bed 5.
Table I: order section inherent frequency analysis results table.
Table II: natural frequency comparison table obtained by spectrogram analysis method and order slice image analysis method
| | Order | 1 natural frequency (Hz) | 2 order natural frequency (Hz) |
| Spectrogram of |
30 | 54 | |
| Order section | 31.5 | 54 |
The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily change or replace the present invention within the technical scope of the present invention. Therefore, the protection scope of the present invention is subject to the protection scope of the claims.
Claims (6)
1. A method for testing natural frequency of a diesel engine test base in a mounting state is characterized by comprising the following steps: the method comprises the following steps:
s1, mounting a diesel engine on a test base, and collecting a vibration time domain signal of the test base and the rotating speed of the diesel engine;
s2, setting different rotating speed grades according to the rotating speed grade of the diesel engine, taking the rotating speed grades as a calculation period, and carrying out Fourier transform on the vibration time domain signal in the step S1 to convert the vibration time domain signal into a vibration frequency domain signal;
s3, placing the vibration frequency domain signal corresponding to each rotating speed gear in the step S2 into a coordinate system to obtain a frequency spectrum curve with the abscissa as frequency and the ordinate as vibration amplitude;
and S4, sequentially analyzing the frequency spectrum curves obtained in the step S3 according to a frequency spectrum graph analysis method and an order slice graph analysis method, and averaging the results to obtain a certain order natural frequency of the test base.
2. The method for testing the natural frequency of the diesel engine test base in the mounting state according to claim 1, characterized in that: and in the step S1, the diesel engine is in an idling state and in a working speed range, and the continuous speed increasing/decreasing is carried out.
3. The method for testing the natural frequency of the diesel engine test base in the mounting state according to claim 1, characterized in that: the spectrum analysis method in the step S4 includes: when a concentrated peak appears in the vicinity of a certain frequency in the spectrum curve described in step S3, it is considered that a certain order natural frequency of the test base exists here.
4. The method for testing the natural frequency of the diesel engine test base in the mounting state according to claim 1, characterized in that: the analysis method of the slice image of the order in the step S4 includes: in the spectrum curve described in step S3, a plurality of order slice images are taken, and the peaks are collected, and when the peak-to-peak frequencies are concentrated at a certain frequency, the frequency is considered to be a certain order natural frequency of the test base.
5. The utility model provides a diesel engine test base installation state natural frequency testing arrangement which characterized in that: the device comprises a PC end, a signal acquisition instrument, a vibration acceleration sensor arranged on a diesel engine test base and a rotating speed sensor used for detecting the rotating speed of the diesel engine;
the PC end is electrically connected with the signal acquisition instrument and is used for acquiring data of the signal acquisition instrument; the signal acquisition instrument is respectively connected with the vibration acceleration sensor and the rotating speed sensor in an electric mode and is used for acquiring the vibration acceleration of the diesel engine test base and the rotating speed of the diesel engine.
6. The diesel engine test base installation state natural frequency testing device of claim 5, characterized in that: the rotating speed sensor is arranged on a fluted disc for measuring the rotating speed on the diesel engine.
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| CN113984392A (en) * | 2021-10-29 | 2022-01-28 | 深圳技术大学 | Online testing and evaluating method for vibration quality of electric drive assembly system |
| CN114413992A (en) * | 2021-12-24 | 2022-04-29 | 上海发电设备成套设计研究院有限责任公司 | Method, device and system for identifying chamber capacity through vibration measurement |
| CN114674417A (en) * | 2022-02-14 | 2022-06-28 | 华能(浙江)能源开发有限公司玉环分公司 | Method for monitoring natural dynamic frequency of each rotating part of complex shafting |
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