1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there
2、from, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2006 SAE International All rights reserved. No part of this publication m
3、ay be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA)
4、 Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org J2747 ISSUED NOV2006 SURFACE VEHICLE RECOMMENDED PRACTICE Issued 2006-11 Hydraulic Pump Airborne Noise Bench Test RATIONALE Not applicable. FOREWORD This document was created to set a standard test method for measure
5、ment of airborne noise from hydraulic pumps commonly used in motor vehicle power steering systems. TABLE OF CONTENTS 1. SCOPE 2 1.1 Purpose. 2 2. REFERENCES 2 3. DEFINITIONS . 2 4. TEST PROCEDURE. 2 4.1 Introduction . 2 4.2 Instrumentation . 2 4.3 Equipment and Facilities. 4 4.3.1 Test Facility . 4
6、4.3.2 Test Stand. 4 4.4 Sample Preparation 5 4.4.1 Pump Mount Fixture Design Guidelines . 5 4.4.2 FRF Measurement for Rigid Body Modes Determination. 6 4.4.3 Belt Drive Connection . 6 4.4.4 Hydraulic System Set-Up 7 4.5 Operation 8 4.5.1 Test System Warm-Up 8 4.5.2 De-aeration of the System 9 4.5.3
7、Test Conditions . 9 5. OUTPUT OF TEST . 12 6. NOTES 12 6.1 Key Words. 12 APPENDIX A 13 SAE J2747 Issued NOV2006 - 2 - 1. SCOPE Communicate the process of accurately measuring sound power levels of positive displacement hydraulic pumps commonly used in ground vehicle steering systems. This recommende
8、d practice defines the pump mounting (pulley, belt tension, isolation), operating conditions (fluid, speed, temperature, pressure), room acoustics, instrumentation, noise measurement technique and data acquisition setup to be used. Included are recommendations for test sample size, and format for da
9、ta presentation/reporting. 1.1 Purpose Record a common method to perform testing among vehicle manufacturer and pump suppliers. 2. REFERENCES 2.1 Applicable Publications The following publications form a part of this specification to the extent specified herein. Unless otherwise indicated, the lates
10、t version of SAE publications shall apply. 2.1.1 ISO Publication Available from ANSI, 25 West 43rd Street, New York, NY 10036-8002, Tel: 212-642-4900, www.ansi.org. ISO 3745:2003 AcousticsDetermination of sound power levels of noise sources using sound pressurePrecison methods for anechoic and hemi-
11、anechoic rooms 2.1.2 IEC Publication Available from International Electrotechnical Commission, 3, rue de Verambe, P.O. Box 131, 1211 Geneva 20, Switzerland, Tel: +41-22-919-02-11, www.iec.ch. IEC 61672-1 ElectroacousticsSound Level MetersPart 1: Specifications IEC 61672-2 ElectroacousticsSound Level
12、 MetersPart 2: Pattern Evaluation Tests 2.1.3 ANSI Publication Available from ANSI, 25 West 43rd Street, New York, NY 10036-8002, Tel: 212-642-4900, www.ansi.org. ANSI S1.11 Specification for Octave-Band and Fractional-Octave-Band Analog and Digital Filters 3. DEFINITIONS 4. PROCEDURE 4.1 Introducti
13、on This procedure is based on ISO Specification 3745 with sound power testing and a 19-microphone array. Details on further test parameters to standardize the measurement of hydraulic pump component airborne noise are provided. 4.2 Instrumentation Multi-channel data acquisition hardware capable of a
14、 sampling rate of 48 kHz. This hardware shall meet class 1 accuracy corresponding to IEC 61672 or be equivalent for the application (precision 0.7 dB or 8%). SAE J2747 Issued NOV2006 - 3 - A tachometer is used to monitor the speed of the component under test and provides a control signal as well as
15、a trigger for data acquisition in sweep modes. Two thermocouples are utilized to monitor the temperature of the component and fluid. Two static pressure transducers to measure pump outlet and inlet pressure. Two dynamic pressure transducers used in the pump outlet circuit are optional. Microphone Ar
16、ray: Microphone and array requirements are defined in ISO 3745 sound power standard. The preferred hemispherical array contains 19 microphones at a 1 meter radius over a reflecting plane as defined in Figure 1 and Table 1. A 0.5 meter array is acceptable if the lowest frequency of interest is met ac
17、cording to ISO 3745. FIGURE 1 - PREFERRED TEST STAND MICROPHONE ARRAY 23 4 5 678910 11 12131415161718XYZ(Up) Pulley 19Component 1 SAE J2747 Issued NOV2006 - 4 - TABLE 1 - PREFERRED MICROPHONE ARRAY COORDINATES Microphone Position X/r Y/r Z/r 1 -0.99 0.00 0.15 2 -0.50 -0.86 0.15 3 0.50 -0.86 0.15 4 0
18、.99 0.00 0.15 5 0.50 0.86 0.15 6 -0.50 0.86 0.15 7 -0.89 0.00 0.45 8 -0.45 -0.77 0.45 9 0.45 -0.77 0.45 10 0.89 0.00 0.45 11 0.45 0.77 0.45 12 -0.45 0.77 0.45 13 -0.66 0.00 0.75 14 -0.33 -0.57 0.75 15 0.33 -0.57 0.75 16 0.66 0.00 0.75 17 0.33 0.57 0.75 18 -0.33 0.57 0.75 19 0.00 0.00 1.00 4.3 Equipm
19、ent and Facilities 4.3.1 Test Facility The test stand is to be installed in a standard, flat-panel, semi-anechoic quiet room. The room shall have a low-frequency cut-off of 250 Hz, but due to the small size of the test components, measurements may be performed down to 200 Hz. The nominal background
20、level of the room is 25 dB(A) with airborne and seismic noise isolation of 20 dB down from outside noise influences. The ambient temperature should not fluctuate from 21 C more than 3 C. The airborne noise performance of the test room should be hemi-anechoic with minimum noise “reflections” per stan
21、dard ISO 3745. Reflective items or anything similar should be removed from the test cell prior to any noise testing. The back ground level of motor noise without belt must be at least 12 dB below the pump overall noise level for the whole speed range. If a test facility has a higher cut-off frequenc
22、y, no data should be reported for the 1/3 octave bands whose center frequencies fall below the cut-off frequency, unless it requested and clearly identified in the test results. 4.3.2 Test Stand The test stand (Figure 5) is comprised of a fully enclosed electric motor (40 HP typically sufficient for
23、 most applications), a silent driveline with journal bearings, and high precision idler pulleys. The motor controller powers the electric motor, and is connected to a control to run sweeps manually or as programmed by the user. A structurally isolated block (1.2 cm (1/2 in) minimum steel or aluminum
24、) serves as a base for the mounting the test component. The base and drive system are mounted on a concrete base with an isolated reflecting plane covering the test stand. A 19-microphone hemispherical array, built according to ISO 3745 specifications, is used for sound power measurements. The micro
25、phone array has a 0.5 m or 1 m radius centered on the accessory component and is positioned on a reflecting plane which may be removeable. The microphone array is to be oriented with the rear microphone behind the pump back cover as shown in Figure 1. SAE J2747 Issued NOV2006 - 5 - 4.4 Sample Prepar
26、ation 4.4.1 Pump Mount Fixture Design Guidelines The component under test is mounted on the test stand using isolators to duplicate a free-free condition above 300 Hz. Rigid body modes in all three mutually perpendicular axis shall be less than 300 Hz. Pump only, does not include belt and hydraulic
27、lines. In general, the line of sight between the microphones in the array and the pump body should not be blocked in any way by the fixture base. Exceptions to this rule include; Hydraulic lines, instrumentation cable, belts, pulley and isolators and brackets between pump and isolators. Fixture Base
28、 (portion below isolators, shown in Figure 2) Base fixture should be steel or aluminum 1.2 cm (1/2 in) thick or more. Base plate and supports should not exceed a vertical height as defined by the lowest microphone position in the array and a line of sight from the microphone to the pump shaft center
29、line. Minimize reflective surface outside the direction of the reflecting plane that can cause acoustic blocking. Isolators No specific brand is recommended. No restriction on the number of isolators. A sufficient number should be used to properly support pump under max belt tension used for testing
30、. Isolator material Natural rubber, HNBR, Neoprene or other suitable electrometric material. Fixtures/brackets between pump and isolators Fixture/bracket are used to couple test pump to isolators. Fixture/brackets should have low acoustic radiation properties (Stiff and high damping). Fixture/bracke
31、t should be machined from solid. Sheet metals of any kind should not be used. Should not exceed 20% to total pump mass. Fixture/brackets should attach to pump only at existing mount locations. Fixture/brackets shall not interconnect pump mounting points around the circumference of the pump to avoid
32、potential to add stiffness to pump housing. Mounting points may be interconnected with the same fixture/bracket as long as the mounting points are inline and are on the same mounting boss. (Minimal effect on pump housing stiffness) Pump Pulley Recommend that pulley intended for use with the pump be
33、used. No specific pulley is required. NOTE: The pulley has a significant influence on the airborne noise measurement and should be carefully chosen when testing to compare pump performance. SAE J2747 Issued NOV2006 - 6 - FIGURE 2 - PUMP MOUNTING AND ISOLATOR LOCATION 4.4.2 FRF Measurement for Rigid
34、Body Modes Determination NOTE: Consistent setup conditions will depend on the component location, belt tension, and choice of isolators. This consistency is a prerequisite to any testing, and repeatable FRF measurements are a validation of this consistency. As a testing requirement, the rigid body m
35、odes should always be below 300 Hz. The Frequency Response Function, FRF, is measured using an accelerometer, appropriate amplifiers, a suitable dynamic signal analyzer and impact hammer. Mount the accelerometer on one of the components mounts. Impact the component in the axis of measurement and acq
36、uire FRF data (acceleration/force) for each direction, from one accelerometer channel at a time a minimum of 3 times. Figure 3 shows an example of a measured FRF on a component and the corresponding rigid body modes below 240 Hz. FIGURE 3 - FRF OF PUMP AND THE CORRESPONDING RIGID BODY MODES BELOW 24
37、0 HZ 4.4.3 Belt Drive Connection With the belt attached, position the power steering pump so that the belt does not rub. Use spacers under the isolators when necessary to meet the height requirement or to achieve the required angle and belt tension. Insert closed-cell foam pieces into the opening of
38、 the reflective plane to reduce belt noise from beneath the plane. The foam should not make contact with the belt. This bracket not allowed as it violates the interconnection rules. These brackets allowed. Mounting points are in line and fall on the same mounting boss. SAE J2747 Issued NOV2006 - 7 -
39、 4.4.3.1 Tension The test is to be run with 300 N 45 N total hubload. The method to measure belt tension is not specified. Tension may be increased to the amount required to keep required to keep belt from slipping. 4.4.4 Hydraulic System Set-Up (Figure 4) This system is comprised of a baffled oil r
40、eservoir with temperature and aeration control, a discharge hydraulic circuit, and a return line feeds oil through a flow meter and returns the used oil back to the main reservoir. FIGURE 4 - HYDRAULIC CIRCUIT SETUP 4.4.4.1 Reservoir The hydraulic circuit feeding the intake side of the pump can util
41、ize either a large reservoir (0.19 m3(50 gallon) or a small reservoir (0.04 m3(10 gallon). A reservoir volume of 0.02 m3(4 gallon) or more is recommended to help maintain control of temperature and aeration. This reservoir maybe connected to a local or “stand by” reservoir. This reservoir is used to
42、 keep the conditioned oil in “standby” near the test components to control intake impedance and oil pressure to the test components. Where a small reservoir is used, a de-aeration procedure must be implemented as part of the test set up. 4.4.4.2 Discharge Circuit The hydraulic circuit on the dischar
43、ge side of the pump will involve a common steel braided line with a needle valve. The needle valve is to be located outside the microphone array. SAE J2747 Issued NOV2006 - 8 - 4.4.4.3 Hose Specification 0.7 Meter total length between pump discharge and needle valve Hose shall be constructed as foll
44、ows. Smooth bore hose constructed of Carbon Black Static Dissipative Teflon with 304 Stainless Steel Wire Braid Reinforcement ID = 1.2 cm nominal Teflon wall thickness = 0.762 mm nominal 20.7 MPa working pressure 0.15 m length of hard tube on both sides of hose section Temperature range 54 C to 232
45、C 4.4.4.4 Needle Valve Specification Stainless Steel Union-Bonnet Needle Valve 0.35 Cv, 0.25 FNPT fitting w/ Regulating Stem 4.4.4.5 Test Fluid Dexron or Mercon labled fluid. The test temperature will be specified at 77 C and 7 C. Record specific fluid used. Return linePressure LineBeltEncoderPressu
46、re Trans. FIGURE 5 - TYPICAL TEST SETUP 4.5 Operation 4.5.1 Test System Warm-Up Warm up the test system prior to data acquisition by operating the hydraulic power steering pump at 2000 pump rpm at 2.76 MPa for 20 minutes. Verify belt tension is per 4.4.3.1 after warm up. SAE J2747 Issued NOV2006 - 9
47、 - 4.5.2 De-aeration of the System NOTE: Greater than normal amounts of air trapped in the fluid can result in noise levels that are also greater than normal. To ensure that noise measurements are representative of a normal operating system, a de-aeration procedure should be performed on the system
48、after any component in the system is changed. Allow the fluid temperature to reach 77 C. Fully close the discharge pressure adjustment valve. Leave the valve closed for no more than 2 seconds, then re-open it. Repeat this step 3 to 5 times. Adjust the discharge pressure back to 2.76 MPa at 2000 pump
49、 rpm, and listen for air bubbles in the system. Air bubbles will cause an intermittent rattling from the pump, and it is usually very obvious when air is present in the system. Repeat these steps as needed until the air is removed from the system. 4.5.3 Test Conditions 4.5.3.1 Steady State Conditions TABLE 2 - CONDITIONS FOR STEADY STATE TESTS. Test Pump Speed (RPM) System Pressure
