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1、INTERNATIONAL STANDARD IS0 107674 First edition 1996-04-01 Hydraulic fluid power - Determination of pressure ripple levels generated in systems and components - Part 1: Precision method for pumps Transmissions hydrauliques - D b) the source impedance amplitude, in newton sec- onds per metre to the p
2、ower of five (Ns)/m, and phase, in degrees, over ten individual har- monics of pumping frequency; c) the anechoic pressure ripple amplitude, in bars), over ten harmonics of pumping frequency; d) the overall r.m.s. anechoic pressure ripple, in bars; e) the blocked acoustic pressure ripple amplitude,
3、in bars, over ten harmonics of pumping frequency; f) the overall r.m.s. blocked acoustic pressure ripple, in bars. This part of IS0 10767 is applicable to all types of positive-displacement pump operating under steady- state conditions, irrespective of size, provided that the pumping frequency is in
4、 the range from 50 Hz to 400 Hz. 1) 1 bar=105Pa=105N/m2 2 Definitions For the purposes of this part of IS0 10767, the fol- lowing definitions apply. 2.1 source flow ripple: Fluctuating component of flowrate generated within the pump, which is inde- pendent of the characteristics of the connected cir
5、- cuit. 2.2 flow ripple: Fluctuating component of flowrate in the hydraulic fluid, caused by interaction of the source flow ripple with the system. 2.3 pressure ripple: Fluctuating component of pressure in the hydraulic fluid, caused by interaction of the source flow ripple with the system. 2.4 anec
6、hoic pressure ripple: Pressure ripple that would be generated at the pump discharge port when discharging into an infinitely long rigid pipe of the same internal diameter as the pump discharge port. 2.5 blocked acoustic pressure ripple: Pressure ripple that would be generated at the pump discharge p
7、ort when discharging into a circuit of infinite im- pedance. 2.6 impedance: Complex ratio of the pressure ripple to the flow ripple occurring at a given point in a hy- draulic system and at a given frequency. 1 Copyright International Organization for Standardization Provided by IHS under license wi
8、th ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/18/2007 19:39:06 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 10767-1:1996(E) 0 IS0 2.7 source impedance: Impedance of a pump at the discharge port. 2.8 harmonic: Sinusoidal component of the pre
9、ss- ure ripple or flow ripple occurring at an integral mul- tiple of the pumping frequency. NOTE 1 A harmonic may be represented by its amplitude and phase, or alternatively by its real and imaginary compo- nents. 2.9 pumping frequency: Frequency given by the product of shaft rotational frequency an
10、d the number of pumping elements on that shaft. It is expressed in hertz. 2.10 shaft rotational frequency: Frequency (in hertz) given by the shaft rotational speed (in r/min) divided by 60. 3.3 Frequency analysis of pressure ripple A suitable instrument shall be used to measure the amplitude and pha
11、se of the pressure ripple, for at least ten harmonics of the pumping frequency. The instrument shall be capable of measuring the pressure ripple from two or three pressure trans- ducers (6.7) such that, for a particular harmonic, the measurements from each transducer are synchro- nized in time with
12、respect to each other. This may be achieved by sampling the pressure ripple from each pressure transducer simultaneously, or by sampling each pressure transducer separately but with respect to a trigger signal obtained from a fixed reference on the pump shaft or secondary source drive, as appro- pri
13、ate. The instruments shall have an accuracy and resolution for harmonic measurements as follows, over the fre- quency range from 50 Hz to 4 000 Hz: a) amplitude within f 1 %; 3 Instrumentation b) phase within + 1”; 3.1 Static measurements The instruments used to measure a) mean fluid flow, b) mean f
14、luid pressure, c) shaft rotational speed, and d) fluid temperature shall meet the temperature for “industrial class” ac- curacy of measurement, i.e. class C given in annex A. 3.2 Dynamic measurements The instruments used to measure pressure ripple shall have the following characteristics: a) resonan
15、t frequency 2 30 kHz; b) linearity rt 1 %. The instruments need not respond to steady-state pressure, and it may be advantageous to filter out any steady-state signal component using a high-pass filter. This filter shall not introduce an additional amplitude or phase error exceeding 1 % or Z”, respe
16、ctively, at the pumping frequency. c) frequency within f 0,5 %. Compliance with the above tolerances will result in an uncertainty in the overall r.m.s. pressure ripple rating of within k 10 %. 4 Pump installation 4.1 General The pump shall be installed in the attitude recom- mended by the manufactu
17、rer and mounted in such a manner that the response of the mounting-to-pump vibration is minimized. 4.2 Drive vibration The prime mover and associated drive couplings shall not generate torsional vibration in the pump shaft. If necessary, the pump and the driving unit shall be isolated from each othe
18、r to eliminate vibration gener- ated by the prime mover. 4.3 Reference signal A means of producing a reference signal relative to the pump shaft rotation shall be included. The signal shall be an electrical pulse occurring once per revol- ution, with sharply defined rising and falling edges. This si
19、gnal is used as a measure of the shaft rotational speed and may be used, if necessary, to provide a 2 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/18/2007 19:39:06 MDTNo reproduction
20、or networking permitted without license from IHS -,-,- 0 IS0 IS0 10767-1:1996(E) trigger signal and/or phase reference for the pressure ripple analysis instrument. 5 Test conditions 5.1 General The required operating conditions shall be maintained throughout each test within the limits specified. in
21、 table 1. 6 Test rig 6.1 General The test rig shall be installed generally as shown in figure 1. The test rig shall include all fluid filters, fluid coolers, reservoirs, loading valves and any ancillary pumps required to meet the pump hydraulic operating conditions. Specific features are described i
22、n 6.2 to 6.13. 5.2 Fluid temperature 6.2 Test fluid The temperature of the fluid shall be that measured at the pump inlet. 5.3 Fluid density and viscosity The density and viscosity of the fluid shall be known to an accuracy within the limits specified in table2. 5.4 Fluid bulk modulus The isentropic
23、 tangent bulk modulus of the fluidshall be known to an accuracy within the limits specified in table2. As this is not always feasible, 5.4.2 details a method by which the bulk modulus may be evai.uated with a sufficiently high accuracy. Table 1 - Permissible variations in test conditions Test parame
24、ter Permissible variath Mean flow + 2 % Mean pressure f 2 % Shaft rotational frequency f 1 % Temperature f 2 “C Table 2 - Required accuracy of fluid property data Isentropic tangent bulk modulus2) 1) See reference I 01. 2) See reference II. The type of test hydraulic fluid and the quality of fil- tr
25、ation shall be in accordance with the pump manu- facturers recommendations. 6.3 Pump The pump shall be installed in the “as-delivered” condition. 6.4 Inlet line The internal diameter of the inlet line to the pump shall be in accordance with the pump manufacturers recommendations. To prevent air leak
26、ing into the cir- cuit, care shall be exercised when assembling the in- let lines. The supply pressure shall be in accordance with the pump manufacturers recommendations and, if necessary, a boost pump shall be used. 6.5 Inlet pressure gauge The inlet pressure gauge shall be mounted at the same heig
27、ht as the inlet fitting or shall be calibrated for any height difference therefrom. 6.6 Pump discharge port connection The adaptor connecting the pump discharge port to the discharge pipe shall have an internal diameter which does not differ from the discharge pipe diam- eter by more than 10 % at an
28、y point. Any such vari- ations in internal diameter shall occur over a length not exceeding twice the internal diameter of the pipe. The adaptor shall be arranged in order to prevent the formation of air pockets in it. The discharge pipe shall be mounted in line with the pump discharge port without
29、any changes in direction. 3 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/18/2007 19:39:06 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 10767-1:1996(E)
30、 Torsional vibration Electric / isolation coupling (if required) Presguge mv Point “A” Secondary I I source Test pump jr-. I L-L 0 Temperature indicator Straight rigid pipe (see figure 2) Load valve Figure 1 - Circuit diagram for secondary-source test rig 6.7 Pump discharge line The discharge pipe s
31、hall be a uniform, rigid, straight metal pipe. Pressure transducers shall be mounted along its length, as shown in figure2. The internal di- ameter of the pipe shall be between 80 % and 120 % of the diameter of the pump discharge port. The pipe shall be supported in such a manner that pipe vibration
32、 is minimized. The pressure transducers shall be mounted such that their diaphragms are flush with the inner wall of the pipe to within * 0.5 mm. No valves, pressure gauges or flexible hoses shall be installed between the pump discharge port and point “A” as shown on figure 1. Two alternative specif
33、ications for the pump discharge line are given, depending on whether the isentropic tangent bulk modulus of the fluid is known within the limits specified in table2. These alternatives are henceforth known as “method 1” and “method 2”. Method 1 is acceptable for use in all situations. How- ever, if
34、the isentropic tangent bulk modulus is known within the limits specified in table2, economies can be made by using method 2. If method 1 is used, set up the pump discharge line as specified in 6.7.1. If method 2 is used, set it up as specified in 6.7.2. 6.7.1 Method 1 Three pressure transducers are
35、required for this method, set up as shown in figure2. The dimensions of the discharge pipe shall be selected according to the pumping frequency. When the series of tests in- cludes a range of pump speeds, the dimensions shall be selected in relation to the minimum pumping fre- quency, fo,-,-,i, in t
36、hat series. The overall length of the discharge pipe, I. and the distance of the pressure transducers from the pump, x, x2 and +, are specified in table3. Table 3 - Pipe length and transducer positions: Method 1 Pipe length and transducer Minimum pumping frequency, Hz positions 5oaf,m,“d 100 100 ,fb
37、,min d 400 Xl x2 x3 1 0,15 m * 1 % 0.85 m k 1 % I,85 m k 1 % at least 2 m 0.1 m f 1 % 0,43 m ? 1 % 0.9 m f 1 % at least 1 m 6.7.2 Method 2 Two pressure transducers are required for this method, set up as shown in figure 2. The length of the discharge pipe and the positions of the pressure transducer
38、s shall be selected according to the pump- ing frequency. When the series of tests includes a range of pumping frequencies, the dimensions shall be selected in relation to the maximum pumping fre- quency in that series. The ratio of maximum to mini- mum speed for a selected transducer spacing shall
39、not exceed 4:l. If the speed range of a test series exceeds this limit, different transducer spacings will be required. 4 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/18/2007 19:39:06
40、 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 10767-1:1996(E) Pressuretransducer Pump k/! Pressure transducers Mounting block for loading valve,reLief valvtzpressuregaugeandsecondary source Figure 2 - Arrangement of discharge pipe The distance between the pressure tr
41、ansducers shall be as given by the following equation, to within 1 %: I 4 (4?ff x Ia?) X2 - ” = (67 x fo, ,.J where f O,max is the maximum pumping frequency, in hertz; B eff is the effective bulk modulus, in bars (see 8.3); e is the density, in kilograms per cubic metre. The first pressure transduce
42、r shall be located as close as possible to the pump flange and no more than (12 -x,) m away. The length 1 shall be at least (x2 + IOd) m, where d is the internal diameter of the pipe. 6.7.3 Calibration of pressure transducers Calibration of the pressure transducers and signal conditioning is necessa
43、ry. Relative calibration shall be performed by mounting the pressure transducers in a common block such that they measure the same pressure ripple. This common block shall be such that the pressure transducers are at the same axial pos- ition and not more than 20 mm apart. Use the secondary source (
44、6.11) to generate pressure ripple. Measure the amplitude and phase relationship between the pressure transducers for a range of fre- quencies spanning the complete range of interest (7.3.2) with one transducer used as a reference. For piezo-resistive transducers, the reference transducer can be cali
45、brated statically using, for example, a dead-weight testing machine. If piezo-electric trans- ducers and charge amplifiers are employed, a cali- brated piezo-resistive transducer may be used as a reference for dynamic calibration purposes. The am- plitude and phase differences at each frequency shal
46、l be known to an accuracy of within 3 % and 2” for method 1, or 3 % and 0,5” for method 2. These dif- ferences shall be corrected in the tests (see clause 7). 6.8 Load valve Loading of the pump shall be effected using a needle valve or equivalent. A valve with freely moving parts, such as a pressure
47、-relief valve, shall not be used for loading purposes. 6.9 Relief valve A relief valve may be fitted for safety purposes. The valve shall be set to relieve at a pressure at least 20 % greater than the mean test pressure. 5 Copyright International Organization for Standardization Provided by IHS unde
48、r license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/18/2007 19:39:06 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 10767-1:1996(E) 0 IS0 6.10 Pressure gauge A pressure gauge shall be fitted as shown in figure 1, together with a throttl
49、ing valve to reduce gauge os- cillation. Alternatively, a pressure transducer may be used. 6.11 Secondary source 6.11.1 A device capable of generating pressure ripple shall be fitted as shown in figure 1. 6.11.2 The pressure ripple from the secondary source shall span the frequency range from the pumping frequency of the test pump to at least ten times the p