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 entirelyvoluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefro
2、m, 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.QUESTIONS REGARDING THIS DOCUMENT: (724) 772-8512 FAX: (724) 776-0243TO PLACE A DOCUMENT
3、 ORDER; (724) 776-4970 FAX: (724) 776-0790SAE WEB ADDRESS http:/www.sae.orgCopyright 1993 Society of Automotive Engineers, Inc.All rights reserved. Printed in U.S.A.SURFACEVEHICLE400 Commonwealth Drive, Warrendale, PA 15096-0001RECOMMENDEDPRACTICEAn American National StandardJ1253REV.JUN93Issued 197
4、9-02Revised 1993-06Superseding J1253 MAR86LOW-TEMPERATURE CRANKING LOAD REQUIREMENTS OF AN ENGINE1. ScopeThe electrical cranking system components, which include the battery, cables, and cranking motor,must be carefully selected to provide the necessary speed to start an engine under the most severe
5、 climaticconditions for which the system is intended. Engine cranking loads increase with cold temperatures, therefore,the initial selection of these components needs to consider low-temperature engine torque requirements. Toinsure an adequate electrical cranking system is obtained, it is important
6、that proper test procedures are usedfor obtaining the cranking load requirements of the engine.2. References2.1 Applicable PublicationsThe following publications form a part of this specification to the extent specifiedherein. The latest issue of SAE publications shall apply.2.1.1 SAE PUBLICATIONSAv
7、ailable from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.SAE J300Engine Oil Viscosity ClassificationSAE J544Electric Starting Motor Test Procedure3. ProcedureThe following test procedure is recommended for obtaining low-temperature cranking torquerequirements:3.1 Engine Preparation3.1.1 T
8、he engine to be tested should be equipped with all accessories that provide parasitic loads, such as powersteering pump, automatic transmission, etc.3.1.2 The engine, if new, should be run in to stabilize friction loadsequivalent to 1500 miles (2400 kilometers) or18 h at 2400 engine rpm.3.1.3 The en
9、gine is winterized with anti-freeze solution for the temperature at which the test will be run.3.1.4 The engine oil selected for the low temperature test should be representative of the high limit viscosity for theSAE grade recommended by the engine manufacturer for the operating temperature range (
10、refer to SAEJ300). Sufficient oil of the same viscosity should be obtained for the complete test program so variations intest results can be minimized.SAE J1253 Revised JUN93-2-3.1.5 Fuel dilution of the engine oil will reduce its viscosity, therefore, to avoid this possibility, the cranking test is
11、run without fuel in the carburetor, or with fuel system cut off.3.1.6 To prepare the engine for test, the engine is warmed up and oil drained hot. This procedure should berepeated two times to assure complete change of oil when oil grade change is made. The oil filter ischanged for the final fill. W
12、hen the same grade of oil is used for other test temperatures and/or additionaltest days, the engine warm up procedure is repeated and only one drain is required.3.1.7 Install a thermocouple in the center of the greatest mass of oil so soak temperatures can be monitored.3.1.8 Equip engine with neces
13、sary instrumentation to provide cranking speed, battery voltage, cranking motorvoltage, and current data. (The cranking speed can be determined from oscillographic current or voltagetraces by calculation of the time span between the current or voltage peaks caused by the cylindercompression loads. T
14、he mean cranking speed is obtained over two consecutive revolutions. The meantorque is obtained by measuring the mean cranking current over the same period and calculated asdescribed in 3.2.)3.1.9 Prior to starting the cold soak period, warm up the engine for approximately 5 to 10 min to circulate o
15、il, runcarburetor bowl dry and disable ignition or cut off fuel system, and adjust throttle plate to the idle position.3.1.10 The engine with the calibrated motor is soaked at the test temperature for a period of 16 to 24 h, which canbe monitored by the oil thermocouple.3.2 Cranking Motor Preparatio
16、nThe cranking motor is used to measure the engine cranking torque. Tominimize performance variances, a new cranking motor should be “run in“ until the motor performancebecomes stabilized prior to calibration which is determining the speed, torque, and current under load using astandard SAE terminal
17、voltage curve (Reference Table 1 of SAE J544) unless otherwise specified.After completion of the cranking load tests, a recalibration curve should be run to verify initial performance.NOTESince torque is proportional to cranking motor current, determination of engine torque can becalculated by obtai
18、ning the cranking motor running torque corresponding to the cranking motor currentmeasured at the test temperature from the performance characteristics of the calibrated crankingmotor and multiplying this value by the proper flywheel ring gear to cranking motor pinion gear ratio.3.3 Cranking Load Te
19、sts3.3.1 A sufficient number of cranking tests should be run to obtain a curve of average torque versus averageengine speed over an approximate range of 30 to 120 engine rpm for gasoline engines, 50 to 150 rpm fordirect injection diesel engines, and 120 to 220 rpm for small indirect injection diesel
20、 engines.3.3.2 To obtain the range of speeds required to plot the torque curve, various battery capacities or a regulated DCpower supply that can simulate desired battery conditions are used to supply the appropriate cranking motorterminal voltages. The batteries are not required to be cold soaked b
21、ut should be maintained at full charge.3.3.3 The cranking time for each test should be approximately 10 s with readings between 5 to 10 s used as theplotting points. Allow a minimum of 30 min additional soak time before performing the next cranking test.3.3.4 Using the test data, calibrated cranking
22、 motor performance characteristics and engine ring gear to crankingmotor pinion gear ratio, calculate the engine torque requirements for each test speed and plot an enginetorque requirement curve as shown in Figure 3 of SAE J544.SAE J1253 Revised JUN93-3-3.3.5 It should be noted that since gear effi
23、ciencies have been neglected, the torque measured is not true enginetorque but that as seen by the cranking motor. However, it provides suitable design and application data fordetermining cranking motor requirements.3.3.6 Once the engine torque requirement curve has been determined and the speed req
24、uired to start the engineis known, cranking motor performance requirements for the engine application can be determined.4. Notes4.1 Marginal IndiciaThe change bar (l) located in the left margin is for the convenience of the user in locatingareas where technical revisions have been made to the previo
25、us issue of the report. An (R) symbol to the leftof the document title indicates a complete revision of the report.PREPARED BY THE SAE CRANKING MOTOR STANDARDS COMMITTEESAE J1253 Revised JUN93RationaleNot applicable.Relationship of SAE Standard to ISO StandardNot applicable.ApplicationThe electrical
26、 cranking system components, which include the battery, cables, and crankingmotor, must be carefully selected to provide the necessary speed to start an engine under the mostsevere climatic conditions for which the system is intended. Engine cranking loads increase with coldtemperatures, therefore,
27、the initial selection of these components needs to consider low-temperatureengine torque requirements. To insure an adequate electrical cranking system is obtained, it is importantthat proper test procedures are used for obtaining the cranking load requirements of the engine.Reference SectionSAE J300Engine Oil Viscosity ClassificationSAE J544Electric Starting Motor Test ProcedureDeveloped by the SAE Cranking Motor Standards Committee
