1 Scope
This document establishes a test procedure for source flow pulsation and source impedance of displacement hydraulic pumps.
This document applies to all types and sizes of positive displacement pumps with pump excitation frequencies in the range of 50 Hz to 400 Hz under steady state conditions.
This document uses the calculation of high impedance pressure fluctuations as an example. An explanation of the method and the theoretical basis of the test procedure is given in Appendix A. The test procedure is called the dual pressure/dual system method. Ratings are given below :
2 Normative references
The contents of the following documents constitute essential provisions of this document through their in-text normative world3 use. Of these, dated references, only the version corresponding to that date applies to this document undated references, the latest version of which (including all revision sheets) applies to this document.
GB/T 17446 Fluid power transmission systems and components ﹑ Glossary (GB/T 17446-2012. ISO 5598.2008.1DT)
3 Terms and definitions
The terms defined in GB/T 17446 and the following terms and definitions apply to this document.
3.1
Source flow pulsationsource flow ripple
The component of flow pulsation generated in a pump (independent of the characteristics of the connection circuit).
Note 1: Since there are two definitions of source flow ripple, they need to be used differently:
--source flow ripple in the standard Norton model, Q. This is the source flow ripple assumed to be generated at the pump outlet, as shown in Figure 1a); --source flow ripple in the modified model, Q; this is the source flow ripple assumed to be generated inside the end glue of the outlet line, as shown in Figure 1b). ) shows that
Note 2: According to the size and structure of the pump, the physical properties of the fluid and operating conditions, the theoretical pump source flow pulsation calculated by computer simulation and the revised model of the dish flow pulsation Q: equivalent.
4 Instrumentation
4.1 Static measurements
The instrumentation is used to measure the following parameters
The test accuracy shall be as specified in Table 1.
Note: The percentage limit is the value of the measured value and not the maximum measured value or maximum reading of the instrument.
5 Installation of the pump
5.1 General rules
The pump should be installed in accordance with the manufacturer's recommendations and in such a way as to minimise the vibration response of the pump.
5.2 Drive vibration
The electric motor and associated drive coupling should not generate torsional vibrations in the pump shaft. If necessary, the pump and drive unit should be isolated from each other to eliminate the effects of motor vibration.
5.3 Reference signal
The reference signal is a signal related to the rotation of the pump shaft and as one of the basic elements of the measurement, the method of obtaining it is included in this document. The reference signal should be an electrical pulse that occurs at each revolution of the pump shaft and has clearly defined rising and falling edges. This signal can be used as an external trigger signal for the analysis of the logger as well as for the measurement of the shaft rotation speed.
6 Test conditions and settings
6.1 General rules
The pump shaft speed, the average outlet pressure and the fluid temperature are set to the values of the required test conditions. For each test, the test conditions shall be as specified in Table 2.
6.2 Average flow rate
The average flow rate is measured by means of a volumetric flow meter installed in the outlet line of the loading valve 2 (see Fig. 2 I 4).
6.3 Average outlet pressure
The average outlet pressure is measured by means of a pressure transducer installed in the transition fitting in front of the loading valve 1 (see Fig. 2 i Fig. 4).
6.4 Pump shaft speed
The pump shaft speed is measured by a speed sensor mounted on the pump shaft. 6.5 Fluid temperature
The temperature of the fluid should be the temperature measured at the pump inlet. 6.6 Fluid properties
The density, viscosity and bulk modulus of the test fluid should meet the accuracy specified in table 3. Note: The percentage limit is the error between the estimated value and the actual value.
7 Test rig
7.1 General rules
The general schematic of the test rig is shown in Figure 2 and should include all filters, coolers, tanks, loading valves and any auxiliary pumps required to meet the operating conditions of the hydraulic pump. Specific requirements are given in 7.2 I 7.10.
7.2 Pump to be tested
The test pump should be installed in the "as-delivered condition".
7.3 Fluid
The type and filter quality of the hydraulic fluid to be tested should be in accordance with the pump manufacturer's recommendations.
7.4 Inlet piping
The internal diameter of the pump inlet line should be in accordance with the pump manufacturer's recommendations. The inlet line should be assembled in such a way as to prevent air leakage into the circuit. The suction pressure should be in accordance with the pump manufacturer's recommendations and, if necessary, a booster pump should be used. If a booster pump is used, the pressure and flow pulsations of the booster pump should be taken into account so that they do not affect the test results.
7.5 Inlet pressure gauge (static measurement)
Bolden tube gauges should be used. The pressure gauge should be installed at the same height as the inlet connection, otherwise the gauge should be calibrated for height difference.
7.6 Pump outlet line
7.6.1 General rules
The outlet line shall be as shown in Figure 3 and shall consist of a functional test section consisting of a reference pipe, a connection pipe, two loading valves, an extension pipe, a safety valve (direct acting relief valve) and a transition joint connection. The piping shall be secured with pipe clamps.
7.7 Pressure sensors
7.7.1 Dynamic pressure sensors
To measure pressure fluctuations, two dynamic pressure transducers are mounted on the transition fittings at the ends of the connecting reference tube. The sensors should be mounted so that their diaphragms are flush with the inner wall of the inner bore of the transition fitting. The dynamic pressure sensor should be able to accurately measure fluctuations in the pump drive shaft rate of at least 10 kHz. The part of the reference tube between the two dynamic pressure sensors forms the measuring section and is analysed for standing waves. In this test method, the section from the outlet end of the pump casing to the pressure sensor (length 10 mm - IB mm) is considered to be part of the internal pump passage.
7.7.2 Static pressure transducer
To measure the average outlet pressure, a static pressure transducer is fitted on the transition fitting before the loading valve 1.
7.8 Loading valve
Use a needle valve or a valve of similar effect to complete the loading of the pump. Valves with free moving parts (e.g. relief valves) should not be used for loading. 7.9 Back pressure valve
Install a needle valve type backpressure valve on the outlet line of the loading valve 2 to prevent cavitation at the loading valve orifice.
7.10 Safety valve
The test circuit should have a safety valve (especially a direct acting relief valve) to protect the test equipment and personnel from extreme line pressures. The safety valve should be installed as close as possible to the test line to minimise the interaction of branch circuits, preferably on the transition fitting before the loading valve 1, and set at a pressure at least 20% higher than the average test pressure.
A diagram of the hydraulic test circuit and measurement system for the dual pressure/dual system method is shown in Figure 4.
8 Test procedure
8.1 Overview
Before starting the test, the pump needs to be run with both loading valves open for a sufficient time to remove air from the system. Adjust the motor speed control, loading valve 1/loading valve and cooler respectively so that the pump speed, average outlet pressure and oil temperature meet the test conditions.
This method assumes that the velocity of sound in the fluid being measured in the reference tube is known. The velocity of sound in the reference tube is determined using the method in Appendix A.
8.2 Frequency analysis of pressure fluctuations
The frequency analysis of pressure fluctuations should be carried out in accordance with the following procedure.
9 Test report
9.1 General and test information
The generic and test information shall be recorded in accordance with the form of Table B.1 and Table Dead 2 in Appendix B.
10 Marking instructions (compliance with this document)
When choosing to comply with this document, it is appropriate to use the following statement in test reports, catalogues and sales literature:
"Pressure fluctuation test method in accordance with GB/T41980.1-2022 "Hydraulic drives: method for determining pressure fluctuations in systems and components Part 1; hydraulic pumps (precision method)".
Appendix A (informative) Dual pressure/dual system method
Appendix B (normative) test forms
Bibliography
1 Scope
2 Normative references
3 Terms and definitions
4 Instrumentation
5 Installation of the pump
6 Test conditions and settings
7 Test rig
8 Test procedure
9 Test report
10 Marking instructions (compliance with this document)
Appendix A (informative) Dual pressure/dual system method
Appendix B (normative) test forms
Bibliography
