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 theref
2、rom, 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 2009 SAE International All rights reserved. No part of this publication ma
3、y 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.orgSURFACEVEHICLERECOMMENDEDPRACTICEJ381 JAN2009 Issued 1968-02Revised 2009-01 Superseding J381 SEP2000 (R) Windshield Defrosting Systems Test Procedure and Performance RequirementsTrucks, Buses, and Multipurpose Vehicles
5、 RATIONALEThe current SAE J381 test procedure provides two separate means of heating the coolant during testing, but these two approaches can provide very different results. If the engine is used to heat the coolant, the engine rpm and engine load criteria are neither clear nor consistent. There are
6、 two distinct reasons to test a defrost system: a. To compare two or more alternative defroster systems during the design process. b. To compare the defroster performance of a specific vehicle and engine configuration to an established standard. This revision recognizes these differences in the reas
7、ons for testing, and provides specific test conditions depending on the test intent. Variations of the test between gasoline and diesel engines are eliminated with the rationale that how well the window clears should not be a function of the engine fuel source. Diesel and gasoline engines in the pas
8、t ran at very different rpms, but today most truck gasoline engines run high idle rpms at similar speeds when compared to their diesel counterparts. The chamber wind condition was increased to up to 5 mph because this is easier for all chambers to meet and this should not significantly affect the re
9、sults Updated the test report template to match the procedure References to the type of cameras that could be used were removed because such specific recommendations do not keep pace with advancements in technology. 1. SCOPE This SAE Recommended Practice establishes uniform test procedures and perfo
10、rmance requirements for the defrosting system of enclosed cab trucks, buses, and multipurpose vehicles. It is limited to a test that can be conducted on uniform test equipment in commercially available laboratory facilities. Current engineering practice prescribes that for laboratory evaluation of d
11、efroster systems, an ice coating of known thickness be applied to the windshield and left- and right-hand side windows to provide more uniform and repeatable test results, even though under actual conditions such a coating would necessarily be scraped off before driving. The test condition, therefor
12、e, represents a more severe condition than the actual condition, where the defroster system must merely be capable of maintaining a cleared viewing area. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,
13、-,-SAE J381 Revised JAN2009 Page 2 of 10Because of the special nature of the operation of most of these vehicles (where vehicles are generally kept in a garage or warmed up before driving) and since defrosting under steady-state over-the-road operations is the main concern, test conditions have been
14、 adopted which assume that the engine is warm before the vehicle is driven. There are two options for producing hot coolant in this recommended practice. Testing using these two approaches on the same vehicle will not necessarily provide identical results. Many vehicle models are offered with option
15、al engines, and each engine has varying coolant temperatures and flow rates. If the test is being conducted to compare the performance of one defroster design to another defroster design, then the external coolant source approach (Test A) will yield the most comparable results. If the test is being
16、conducted to validate the defroster installation on a specific vehiclemodel with a specific engine, then using the engine to heat the coolant (Test B) will be more appropriate.This document will be reviewed and revised as technological progress in vehicle defroster test procedure requires. 2. REFERE
17、NCES 2.1 Applicable Publications The following publications form a part of the specification to the extent specified herein. Unless otherwise indicated, the latest revision of SAE publications shall apply. 2.1.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, P
18、A 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org.SAE J941 Motor Vehicle Drivers Eye Locations 3. DEFINITIONS 3.1 Defrost To remove ice or frost from the surface of automotive glass surfaces. 3.2 Windshield Defroster System A heating device designed t
19、o defrost the windshield and specified portions of the front right and front left side windows. 3.3 Defrosted Area That area of the glass surface that is free of frozen ice or frost. 3.4 Coolant Liquid used for heat transfer composed of 50% ethylene glycol/50% water or other liquids specified by veh
20、icle manufacturer for use in the heat transfer system. 3.5 Daylight Opening (DLO) The maximum opening of any glass aperture which is unobstructed by moldings, masking, or framing. 3.6 High Idle A feature provided by the vehicle OEM to run the engine above the normal idling speed, typically used to p
21、rovide additional power during operation of power take-off equipment or for warming up the engine. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J381 Revised JAN2009 Page 3 of 104. DEFROSTING T
22、EST 4.1 General Purpose Requirements The windshield area to be defrosted was developed to be compatible with vision requirements necessary to operate trucks, buses, and multipurpose vehicles. The area is based on SAE J941 with certain modifications to accommodate the wide variety of conditions encou
23、ntered in these vehicles. For the purpose of this document, the head turn consideration in SAE J941 will not be used. 4.2 Test Equipment 4.2.1 Environmental chamber sufficiently large to contain the basic vehicle or basic vehicle body or partial body with provision for circulating air. 4.2.2 Means f
24、or recording the boundaries of the windshield areas defrosted (markers or photographic equipment). 4.2.3 Engine tachometer with an accuracy of 2% of observed values. 4.2.4 Stopwatch or other timing device. 4.2.5 Thermometers, thermocouples, or other temperature measuring devices with an accuracy of
25、0.5 C. 4.2.6 Throttle control device (if desired). 4.2.7 Spray gun for applying distilled water to the windshield and side windows with the following characteristics: FluidWaterLiquid nozzle size diameter1.7 mm (0.070 in) Operating gun gauge pressure345 kPa (50 psig) Airflow rate0.34 m3/min 0.03 m3/
26、min (12 ft3/min 1 ft3/min)Pattern at 200 mm (8 in) from surface250 mm 50 mm (10 in 2 in) wide 4.2.8 Device for measuring the quantity of water applied to the windshield and side windows. 4.2.9 Auxiliary power supply for powering the defroster blower motor. 4.2.10 Anemometer to measure air velocity w
27、ith a measuring accuracy of 1.6 km/h (1 mph). 4.2.11 Independent coolant supply to provide coolant flow to the heater-defroster system under test. 4.2.12 Instrument for measuring voltage and amperage. 4.3 Test Conditions 4.3.1 Coolant Source TEST A: Independent coolant supply.TEST B: Engine running
28、at 1500 rpm 50 rpm in neutral gear or the high idle RPM set by the vehicle OEM, whichever is higher. An auxiliary means for preheating the engine is permissible to provide easier engine starting. Engine speed shall be maintained with no load (normal engine parasitic loads only) throughout the test.
29、4.3.2 Heater Defroster System Coolant Flow TEST A: 11.4 kg/min 2.3 kg/min (25 lb/min 5 lb/min) TEST B: With engineThat flow resulting from engine operation as prescribed in 4.3.2. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted
30、without license from IHS-,-,-SAE J381 Revised JAN2009 Page 4 of 104.3.3 Heater Defroster System Coolant Temperatures TEST A: To be maintained at 65 C + 3 C/0 C (150 F + 5 F/0 F) for the entire test period TEST B: To be at 65 C 3 C (150 F 5 F) at the start of the test, or the maximum temperature that
31、 the engine can produce at the test conditions if it cannot reach this value. Coolant temperature after the start of the test is to be a function of the engine temperature control characteristics at the test conditions.4.3.4 Environmental Chamber Temperature 18 C 2 C (0 F 4 F). 4.3.5 Environmental C
32、hamber Air Velocity The maximum wind speed measured 915 mm (36 in.) in front of the windshield shall not exceed 8 km/h (5 mph). 4.3.6 Environmental Chamber Air Temperature The ambient air temperature shall be measured at a point that is located at the midpoint of the windshield 915 mm (3 ft) ahead o
33、f the windshield surface. As the test proceeds, this temperature shall not exceed 12 C (+10 F). 4.3.7 Number of Vehicle Occupants During the Test Two maximum. 4.3.8 Windshield Wipers Wiper blades and arms are to be off the windshield glazing surface during the ice application. Windshield wipers are
34、allowed to be used during the test. If windshield wipers are used, the number of wiper cycles and times are to be listed in the report. 4.3.9 Defroster and Heater System Settings Defroster Blower Fan(s): Max Speed Selection Mode: Defrost Recirc Mode: Fresh Air Temp Control: Max Heat 4.3.10 Test Volt
35、age 15% over the nominal system rating at the blower motor (for example, 13.8 V on 12 V system) or the supply end of motor dropping resistor. NOTE: Blower motor voltage and current are to be measured as close to the motor as possible and the distance documented.4.3.11 Test Components All engine, hea
36、ter, and defroster units shall be standard production parts or equivalent, adjusted to the manufacturers specified limits. 4.3.12 Cab Configuration Engine hood, doors, windows, and controllable vents shall be closed. Operation of the side windows is not permitted during the test. Use of the bunk cur
37、tain should be consistent, whether closed or open, throughout the test series. Bunk blower off, if applicable. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J381 Revised JAN2009 Page 5 of 104.3
38、.13 Auxiliary Heaters If an auxiliary heater (or heaters) is part of the standard heater and defroster system, it may be operated. 4.3.14 For systems using an electrically conductive heating medium integral with glazing material and if a coolant heater defroster means is not used the references to c
39、oolant control does not apply.4.3.15 For systems that include an electrically conductive heating medium integral with the glazing material, set the control to its maximum setting. 4.4 Test Instrumentation 4.4.1 Coolant Temperature The temperature of the engine coolant or the independent supply coola
40、nt shall be measured as near to the inlet line of the heater unit as possible, but not farther than 152 mm (6 in) from the heater inlet and outlet tubes. For those systems using more than one heater, it shall be measured at the inlet line of the heater unit getting the first coolant flow. 4.4.2 Cool
41、ant Flow The coolant flow may be measured at any convenient point in the independent coolant supply system. 4.4.3 Glass Temperature The windshields interior surface temperature(s) shall be measured at a point located on the vertical and horizontal centerline(s) of the windshield(s). 4.4.4 Defrost Pa
42、ttern Marking Photographic Method: Mount the cameras so that they are positioned perpendicular to the surface of the glass. Use a sufficient number of cameras so that each section of glass (windshield and side windows) can be photographed without distortion.Marker Method: Use dry-erase type marker o
43、r wax pencil to mark the lines on the glass as the test proceeds. The line of the receding ice is determined by identifying the edge where the ice ends (if the windshield wipers are running), or the transition between the wet ice and the grey ice, see Figure 1. 4.5 Test Procedure 4.5.1 Vehicle Soak
44、Period Soak time in the environmental chamber prior to ice application shall be a minimum of 4 hours unless instrumentation is available to assure that the windshield, cab, and HVAC system with ductwork are stabilized at the test temperature. 4.5.2 Ice Application Following the vehicle soak period,
45、a coating of ice shall be formed on the windshield(s) as follows: The windshield(s) shall be sprayed with 0.05 mL of water per square centimeter of glass area (0.05 mL/cm2= 0.01 oz/in2) applied by means of a spray gun with 345 kPa 35 kPa (50 psi 5 psi) air pressure at the device, measured while spra
46、ying to form an even coating of ice over the entire glass surface. The spray nozzle (adjusted to full fan pattern and maximum flow) is held perpendicular to and 200 to 250 mm (8 to 10 in) from the glass, and stroked back and forth evenly in horizontal overlapping layers until the specified quantity
47、of liquid is applied. Upon completion of the icing process, an additional soak period of not less than 30 min and not more than 40 min shall have elapsed before start of the test. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted
48、without license from IHS-,-,-SAE J381 Revised JAN2009 Page 6 of 104.5.3 Coolant Temperature Control Prior to the start of the test period, while the engine or independent coolant supply is being warmed up, the temperature at locations specified in 4.4.2 and 4.4.3 shall not exceed 12 C (+10 F).4.5.4 Start Test The test period begins when the conditions are met as specified in 4.3.3. Turn on the blower(s) and begin timing.4.5.5 Record Data Record results every 5 min for a total of 30 min: All in-cab temperatures per Table in Figure 2. The
