1、BRITISH STANDARD BS 7275-3: 1995 ISO 4392-3: 1993 Determination of hydraulic fluid powermotor characteristics Part 3: Method at constant flow and at constant torque UDC 621.8.032:621.225.4BS7275-3:1995 This British Standard, having been prepared under the direction of the Engineering Sector Board (E
2、/-), was publishedunder the authority ofthe Standards Board and comes into effect on 15March1995 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference MCE/18 Draft for comment 92/78189 DC ISBN 0 580 23859 8 Committees responsible for this British Standard
3、The preparation of this British Standard was entrusted to Technical Committee MCE/18, Fluid power systems and components, upon which the following bodies were represented: Association of British Mining Equipment Companies British Compressed Air Society British Fluid Power Association British Hydrome
4、chanics Research Association British Steel Industry Department of Trade and Industry (National Engineering Laboratory) Ministry of Defence University of Bath Amendments issued since publication Amd. No. Date CommentsBS7275-3:1995 BSI 10-1999 i Contents Page Committees responsible Inside front cover
5、National foreword ii Introduction 1 1 Scope 1 2 Normative references 1 3 Definitions 1 4 Symbols 1 5 Test installation 2 6 Pretest data 4 7 Test conditions 4 8 Test procedure 5 9 Expression of results 5 10 Test report 7 Annex A (normative) Classes of measurement accuracy 8 Annex B (normative) Use of
6、 practical units 8 Figure 1 Typical hydraulic test circuit 3 Table 1 Symbols and units 2 Table A.1 Permissible systematic errors of measuring instruments asdetermined during calibration 8 Table B.1 Practical units 8 List of references Inside back coverBS7275-3:1995 ii BSI 10-1999 National foreword T
7、his Part of BS 7275 has been prepared by Technical Committee MCE/18. It is identical with ISO 4392-3:1993 Hydraulic fluid power Determination of characteristics of motors Part 3: At constant flow and at constant torque, published by the International Organization for Standardization (ISO). The Techn
8、ical Committee has reviewed the provisions of ISO 4391:1983 and ISO5598:1985 to which normative reference is made in the text, and has decided that they are acceptable for use. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are r
9、esponsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-references International Standard Corresponding British Standard ISO 1219-1:1991 BS 2917 Graphic symbols and circuit diagrams for fluid power systems and comp
10、onents Part 1:1993 Specification for graphic symbols (Identical) ISO 3448:1992 BS 4231:1992 Classification for viscosity grades of industrial liquid lubricants (Identical) ISO 4409:1986 BS 4617:1983 Methods for determining the performance of pumps and motors for hydraulic fluid power transmission (T
11、echnically equivalent) ISO 8426:1988 BS 7250:1989 Methods for determining the derived capacity of hydraulic fluid power positive displacement pumps and motors (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 8, an inside back cover
12、and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS7275-3:1995 BSI 10-1999 1 Introduction In hydraulic fluid power systems, power is transmitted and controlled throu
13、gh a fluid under pressure within an enclosed circuit. Hydraulic motors are units which transform hydraulic energy into mechanical energy, usually with a rotary output. 1 Scope This part of ISO 4392 describes a method of determining the low-speed characteristics of positive-displacement rotary fluid
14、power motors under constant flow and constant torque conditions. Motors may be of either the fixed or variable-displacement type. The method involves testing at slow speeds, which may generate frequencies having a significant influence upon the steady continuous torque output of the motor and affect
15、 the system to which the motor would be connected. The accuracy of measurement is divided into three classes, A, B and C, which are explained in Annex A. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this part of ISO
16、 4392. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of ISO 4392 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC an
17、d ISO maintain registers of currently valid International Standards. ISO 1219-1:1991, Fluid power systems and components Graphic symbols and circuit diagrams Part 1: Graphic symbols. ISO 3448:1992, Industrial liquid lubricants ISO viscosity classification. ISO 4391:1983, Hydraulic fluid power Pumps,
18、 motors and integral transmissions Parameter definitions and letter symbols. ISO 4409:1986, Hydraulic fluid power Positive displacement pumps, motors and integral transmissions Determination of steady-state performance. ISO 5598:1985, Fluid power systems and components Vocabulary. ISO 8426:1988, Hyd
19、raulic fluid power Positive displacement pumps and motors Determination of derived capacity. 3 Definitions For the purposes of this part of ISO 4392, the definitions given in ISO 4391 and ISO 5598 and the following definition apply. 3.1 complete motor cycle the total angular movement of the motor ou
20、tput shaft needed to achieve a repetitive leakage and/or torque recording. In most motors this will be 360; however, in some, such as gear motors, it may be several shaft revolutions 4 Symbols 4.1 The physical quantity letter symbols and their suffixes used in this part of ISO 4392 are in accordance
21、 with ISO 4391. Units are given in Table 1. 4.2 The graphical symbols used in Figure 1 are in accordance with ISO 1219-1.BS7275-3:1995 2 BSI 10-1999 Table 1 Symbols and units 5 Test installation 5.1 Hydraulic test circuit 5.1.1 A hydraulic test circuit similar to that shown in Figure 1 shall be used
22、. WARNING The basic circuit shown in Figure 1 does not incorporate all the safety devices necessary to protect against damage in the event of component failure. It is important that those responsible for carrying out these tests give due consideration to safeguarding both staff and equipment. 5.1.2
23、A fluid-conditioning circuit (Figure 1) together with shut-off valve 5 and relief valve 7 shall be installed. Valve 5 may be opened to facilitate operation at high speed in order to reach the test operating temperature rapidly (see 8.2). Valve 5 shall be closed during the test. 5.1.3 A fluid-conditi
24、oning circuit shall be installed which provides the filtration necessary to protect the test motor and the other circuit components and which will maintain the fluid temperatures specified in clause 7. 5.1.4 A constant motor supply flowrate is obtained by a flow control valve with viscosity and pres
25、sure compensation. 5.1.5 Constant torque load can be obtained using a positive-displacement pump and a flow control valve with a torque signal electric feedback (or a magnetic power brake or any other suitable system). 5.2 Test apparatus 5.2.1 A test rig shall be set up which makes use of the test c
26、ircuit specified in 5.1 and which provides the equipment shown in Figure 1. 5.2.2 A positive-locking device shall be provided on continuously variable displacement motors to prevent the displacement inadvertently changing during the pertinent portion of each test. 5.3 Instrumentation 5.3.1 Measuring
27、 instruments shall be selected and installed to measure the following test motor data: a) inlet flow; b) inlet temperature (see ISO 4409 for guidance on location of the tapping point); c) inlet and outlet pressures (see ISO 4409 for guidance on location of tapping points); d) output torque; e) speed
28、 and angular position of the motor shaft. 5.3.2 The systematic errors of the measuring instruments shall be consistent with the chosen class of measurement accuracy (see Annex A). 5.3.3 Appropriate recording instruments shall be selected and installed which are capable of resolving signals at freque
29、ncies greater than10times the highest expected fundamental data frequency. Quantity Symbol Dimension a SI unit b Rotational speed n T 1 r/min Pressure, differential pressure p, %p ML 1 T 2 Pa Flowrate q L 3 T 1 m 3 /min Torque T ML 2 T 2 Nm Time t T s Swept volume V L 3 m 3 Temperature G C a M = mas
30、s; L = length; T = time; G = temperature. b The practical units which may be used for the presentation of results are given in Annex B.BS7275-3:1995 BSI 10-1999 3 Key 1 Motor under test 2 Constant torque load (positive-displacement pump) 3 Torque, rotational speed and rotational angle meter 4, 7 Rel
31、ief valves 5 Shut-off valve 6 Constant flow device 8, 9 Displacement pumps 10, 11, 12 Torque control devices 13 Flowmeter 14, 15 Pressure indicators 16 Temperature indicator Figure 1 Typical hydraulic test circuitBS7275-3:1995 4 BSI 10-1999 5.3.4 The test measurements should be taken at equal increm
32、ents of shaft angle, and their number should be a minimum of ten times the number of displacement pulses per revolution as obtained under6.1 b). 6 Pretest data 6.1 Using the motor manufacturers data and other known facts, gather the pretest data as follows. a) Calculate the rated (geometric or theor
33、etical) torque of the motor (T g,nor T i,n ) based upon its geometric or theoretical displacement at rated pressure, using the formula or where b) Determine the number of displacement pulses per revolution of the motor shaft, taking into account any gearing which would influence the frequency. c) Ca
34、lculate the fundamental data frequency, f e , in hertz, using the formula where n eis the test speed, in revolutions per minute (r/min). The number of displacement pulses is taken from 6.1 b). 6.2 Using the motor manufacturers recommended value for rated speed, n n , calculate the ideal (geometric o
35、r theoretical) flow at rated speed, qv g,nor qv i,n , using the formula 6.3 Determine the fluid viscosity in accordance with ISO 3448. 6.4 Estimate the maximum output torque expected to be produced by the motor during the test using the rated torque, T g,nor T i,nas determined in 6.1 a). 6.5 The mom
36、ent of inertia of all the rotating components connected to the motorshaft and the volume between the flow-control valve and the motor inlet port should be kept to a minimum. 7 Test conditions The following test conditions shall apply: a) fluid temperature, , at motor inlet: either50 C or 80 C; b) us
37、e a hydraulic fluid of a type and viscosity approved by the hydraulic motor manufacturer, appropriate to the test temperature selected; c) carry out tests at 50 % and 100 % of the motor rated torque; d) for the two torque conditions given in clause7 c), establish the minimum inlet flow; the lowest p
38、ossible flow is that which causes the motor to stop rotating; e) for variable-displacement motors, select the minimum and maximum displacements recommended by the manufacturer; then test at these minimum and maximum displacements; f) for reversible motors, carry out the test in both directions of ro
39、tation. %p n is the rated differential pressure; V g is the geometric swept volume; V i is the derived swept volume (seeISO8426). qv g,n= n n V g or qv i,n= n n V i f e n e 60 - number of displacement pulses =BS7275-3:1995 BSI 10-1999 5 8 Test procedure 8.1 Connect the instrumentation and recording
40、apparatus to record the motor test data as listed in5.3.1 and shown in Figure 1. NOTE 1Before starting the test, fill the motor case with fluid, if necessary. 8.2 Operate the test circuit before taking measurements, in order to stabilize the system temperature. 8.3 Hold the torque as constant as pos
41、sible, while peak-to-peak torque variations should be at least within4 % of the mean value. The requirement specified in 5.3.3 shall be taken into consideration. 8.4 Hold the flow as constant as possible, and record it. Instantaneous flow variation shall be kept to within4 % of the mean value in acc
42、ordance with the specifications given in 5.3.3. 8.5 Maintain the measured inlet fluid temperature constant to within 2 C for the duration of a recording. 8.6 Make simultaneous recordings of the variables listed in 5.3.1 for the required test conditions. 8.7 Extend the recording to as many revolution
43、s as are necessary to achieve one complete motor cycle. 8.8 When using digital data acquisition techniques, select a sample interval which provides 95 % confidence that the maximum and minimum values of speed and pressure have been determined by pretesting. 9 Expression of results NOTE 2Refer to cla
44、use 4 for an explanation of symbols and suffixes. 9.1 Determine the speed n for equally distributed positions over one complete motor cycle. Calculate the mean speed over one complete motorcycle, n ma : where the suffixes 1, 2, 3 . . . z, are the respective selected shaft positions; z is the number
45、of readings per complete motor cycle, in compliance with 5.3.4. 9.2 Calculate the speed irregularity at each selected shaft position %n , using the following formula: 9.3 Calculate the mean speed irregularity over one complete motor cycle, %n ma : 9.4 Determine the speed irregularity index, Ir n , u
46、sing the following formula: 9.5 Calculate the average volumetric efficiency, v,ma , for at least one complete motor cycle using the following formula: where or V i,ma is the average derived swept volume (seeISO 8426:1988, B.2); n ma is the mean rotational speed;BS7275-3:1995 6 BSI 10-1999 9.6 Calcul
47、ate the relative peak-to-peak variation in speed n, using the following formula: 9.7 Determine the effective differential pressure, %pe e, , for the selected positions over one shaft revolution: where 9.8 Calculate the mean effective differential pressure, %p e,ma , over one complete motor cycle usi
48、ng the following formula: 9.9 Calculate the pressure irregularity, %(%p e ), for each selected shaft position using the following formula: 9.10 Calculate the mean differential pressure irregularity, %(%p e,ma ), over one complete motor cycle using the following formula: 9.11 Determine the differenti
49、al pressure irregularity index, Ir %p , using the following formula: or 9.12 Calculate the average hydraulic mechanical efficiency, hm,ma , using the following formula: 9.13 Calculate the relative peak-to-peak variations of differential pressure, %p, using the following formula: qv e is the volume flowrate. %pe e,= pe 1, pe 2, p 1 is the inlet pressure; p 2 is the outlet pressure. %p e,: ()%p e,ma %p e,: =BS7275-3:1995 BSI 10-1999 7 10 Test report 10.1 General The relevant test dat
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