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GB/T 7184-2008 English PDF (GBT7184-2008)

GB/T 7184-2008 English PDF (GBT7184-2008)

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GB/T 7184-2008: Small and medium power diesel engines -- Measurement and evaluation of vibration

This standard specifies the measurement methods and rating criteria for the vibration of the non-rotating and non-reciprocating parts of reciprocating diesel engines. Shaft vibrations (including torsional vibrations) are outside the scope of this standard. This standard is applicable to the reciprocating-piston diesel engines with rigid or flexible support. The typical applications are diesel engines for low-speed trucks, three-wheeled vehicles, tractors, irrigation pumps, marine main engines, marine auxiliary engines, generator sets, etc.
GB/T 7184-2008
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 27.020
J 90
Replacing GB/T 7184-1987, GB/T 10397-2003
Small and medium power diesel engines -
Measurement and evaluation of vibration
ISSUED ON. AUGUST 11, 2008
IMPLEMENTED ON. FEBRUARY 01, 2009
Issued by. General Administration of Quality Supervision, Inspection and Quarantine;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
Introduction ... 4
1 Scope ... 6
2 Normative references ... 6
3 Terms and definitions ... 7
4 Method for vibration measurement ... 7
5 Rating criteria for vibration ... 11
Appendix A (Normative) Rating of machine?€?s vibration ... 13
Appendix B (Informative) Record for measurement of vibration of reciprocating diesel engine ... 15
Appendix C (Informative) Nomogram of grade of vibration severity ... 17 Appendix D (Informative) Classification of machine?€?s vibration ... 19
References ... 21
Foreword
This standard is a revision of GB/T 7184-1987 ?€?Small and medium power diesel engines - Measurement and evaluation of vibration?€? and GB/T 10397-2003
?€?Small and medium power engines - Evaluation of vibration?€?.
The main differences between this standard and the revised standard are as follows.
- EXTEND the scope of application;
- IMPROVE the vibration measurement and rating scales;
- MODIFY the conditions of measurement;
- ADD Appendix D, to provide a reference table for the classification of vibration of reciprocating diesel engine.
Appendix A of this standard is normative. Appendix B, Appendix C and
Appendix D are informative.
This standard, from the date of implementation, replaces GB/T 7184-1987 and GB/T 10397-2003.
This standard was proposed by the China Machinery Industry Federation.
This standard shall be under the jurisdiction of the National Internal Combustion Engine Standardization Technical Committee (SAC/TC 177).
Drafting organizations of this standard. Shanghai Internal Combustion Engine Research Institute, Mianyang Xinchen Power Machinery Co., Ltd., Guangxi Yuchai Machinery Group Co., Ltd., Shanghai Automotive Group Co., Ltd.
Technology Center.
The main drafters of this standard. Yuan Weiping, Ye Huaihan, Cai Xiangru, Wang Liqiang, Wang Jianzhong, Wang Hongjian, Luo Zhijian, Chen Weifang. This standard replaces the standard previously issued as follows.
- GB/T 7184-1987;
- GB 10397-1989, GB/T 10397-2003.
Small and medium power diesel engines -
Measurement and evaluation of vibration
1 Scope
This standard specifies the measurement methods and rating criteria for the vibration of the non-rotating and non-reciprocating parts of reciprocating diesel engines. Shaft vibrations (including torsional vibrations) are outside the scope of this standard.
This standard is applicable to the reciprocating-piston diesel engines with rigid or flexible support. The typical applications are diesel engines for low-speed trucks, three-wheeled vehicles, tractors, irrigation pumps, marine main engines, marine auxiliary engines, generator sets, etc.
This standard also applies to matched machines that are driven by
reciprocating machines or that drive reciprocating machines. For the purposes of this, it shall follow the relevant criteria and rating for assessment. This standard does not apply to reciprocating diesel engines which have a power greater than 100 kW and is installed on road vehicles (such as industrial trucks).
The rating criteria as provided by this standard apply to operational monitoring and acceptance tests, to assess the adverse effects of mechanical vibration of diesel engines on equipment which is directly installed on diesel engines. The rating criteria as provided in this standard do not apply to the assessment of internal parts of diesel engines. For example, problems related to valves, pistons, piston rings, etc. may not be reflected in the measurement, the identification of these problems requires the use of research techniques. The same noise is also not within the scope of this standard.
2 Normative references
The provisions in following documents become the provisions of this standard through reference in this standard. For the dated references, the subsequent amendments (excluding corrections) or revisions do not apply to this standard; however, parties who reach an agreement based on this standard are
encouraged to study if the latest versions of these documents are applicable. For undated references, the latest edition of the referenced document applies. accuracy as required by the measuring system. For the reciprocating diesel engine which has a power of 100 kW or less, it only requires measure the root mean square of the velocity, which can also be obtained indirect measurement through signal processing.
Both the frequency response and the measured vibration amplitude are related to the method of fixing the sensor. It is especially important to maintain a reliable fixation between the sensor and the diesel engine at high vibration values. For example, the GB/T 14412 has a guide on the installation of accelerometer. 4.2 Position of measuring point and direction of measurement
In order to ensure that the rating of vibration measurement is as uniform as possible, thus carrying out accurate comparison of different diesel engines, the recommended positions of measurement are as shown in Figures 1 ~ 4. Usually it must carry out measurement at these positions of measuring points along the three primary directions as related to the diesel engine.
The diesel engine as shown in Figures 1 ~ 4 is only an example. For different types of diesel engines (such as star-shaped engines), it may use the similar measuring points.
If, based on the experience of similar diesel engines, it can predict the position of the maximum vibration severity, it is not necessary to consider all the measuring points as specified in the Figure. However, it shall include the positions of the bearing that is easily accessible to the load. For the acceptance test, if the number of measuring points used is small, it shall be agreed otherwise between the manufacturer and the customer.
If it wants to study it more carefully or compare it, it shall give priority to using the measuring points in Figures 1 ~ 4.
When selecting the appropriate measuring points, it shall consider the structural arrangement and installation restrictions of the specific diesel engine under testing. All the selected measuring points shall be able to properly fix the vibration sensor on the main structure of the diesel engine.
Measuring the vibration of parts as installed in a diesel engine can provide useful information about the failure, but the guidelines as listed in this standard apply only to the position of the measuring points as given in Figures 1 ~ 4 on the main structure of the diesel engine.
Example
It is marked at the right edge of the rack, at the diesel engine?€?s coupling end, along the Y (horizontal) direction as follows.
the maximum vibration which occurs within the range of rated power and speed under normal operation.
4.4 Recording of measurement results
The records of measurement results shall include the basic data of the diesel engine and the use of the measurement system, which shall be included in Table B.1 and Table B.2 in of Appendix B which are used as the measurement record.
5 Rating criteria for vibration
The grade of vibration severity is as shown in Table 1 and are as shown graphically in Appendix C. For quantitative indication, for a reciprocating diesel engine with a power of 100 kW or less, it is only necessary to measure the (wideband) root mean square value of speed in the range of 2 Hz ~ 1000 Hz, calculate the grade of vibration severity at the maximum integrated root mean square value of the speed as measured on the main structure of the diesel engine, use this for rating. If the customer needs, it may measure the root mean square value of the displacement and the acceleration in this frequency band, the results are only for reference but not used for rating purposes. For the reciprocating diesel engine which has a power greater than 100 kW, it must measure the integrated (wideband) root mean square value of displacement, velocity, acceleration in the range of 2 Hz ~ 1000 Hz, calculate the grade of vibration severity at the maximum integrated root mean square of each
displacement, velocity, acceleration as measured on the main structure. The maximum value of these three grades is the scale for assessing the grade of vibration severity of the diesel engine.
Table 1 -- Grade of vibration severity (2 Hz ~ 1000 Hz)
Grade of vibration
severity
Integrated vibration limit as measured on the main structure of diesel engine Displacement /
??m (r.m.s)
Speed /
(mm/s) (r.m.s)
Acceleration /
(mm/s2) (r.m.s)
Appendix B
(Informative)
Record for measurement of vibration of reciprocating diesel engine
Table B.1 -- Record for measurement of vibration of reciprocating diesel engine
Overview
Record number.
Date.
Location of installation.
Measurement personnel.
Specification of reciprocating diesel engine
Type. Diesel engine / Compressor a
Identification number of machine. _____
Corresponding speed. _____ r/min
Support. rigid/flexible a; direct/on foundation
Function. Drive / Driven a
Structural layout. Single-row horizontal-type / in-line
type; V-shaped, opposite layout a
Working cycles. two/four stroke a; single/double
action a
Connection. Rigid/flexible a
Specification of measuring system
Whether the measuring system complies with the requirements of 4.1 of this standard, that is, whether the accuracy of the root mean square is ??10% in the range of 10 Hz ~ 1000 Hz, is ___ in the range of 2 Hz ~ 10 Hz? Yes / No a
Measurement results
The measurement sketch of diesel engine is as follows. Follow the requirements of Figures 1 ~ 4 in this standard to indicate the position of measuring point.
Measured values. Record them into Table B.2.
It shall be attached with the measurement records, spectrum, charts, etc. Meanwhile provide the direction of measuring points as well as the speed and power at the time of measurement, if applicable.
Measurement directions. As relative to the axis of crankshaft (see Figures 1 ~ 4 of this standard) X - Axial direction; Y - Horizontal lateral direction; Z - Perpendicular direction. a It may be deleted/supplemented if necessary.

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