1、_ SAE Technical Standards Board Rules SURYLGHWKDW7KLVUHSRUWLVSXEOLVKHGE6$(WRDGYDQFHWKHVWDWHRIWHFKQLFDODQGHQJLQHHULQJVFLHQFHV7KHXVHRIWKLVUHport is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising WKHUHIURPLVWKHVROHUHVSRQVLELOL
2、WRIWKHXVHU SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2014 SAE International All rights reserved. No part of this publication may be reproduced, stored
3、 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: +1 724-776-4970 (outside USA) Fax: 724-776-0790 Em
4、ail: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/J2985_201402 SURFACE VEHICLE RECOMMENDED PRACTICE J2985 FEB2014 Issued 2014-02 Definition and Measurement of Transfer
5、 Case Speed-Dependent Parasitic Loss RATIONALE New government regulations that raise automotive fuel economy requirements and change the methods by which vehicle level fuel economy is measured drive the need for improved methods to measure component level parasitic loss. The intent of this standard
6、is to provide the means to generate consistent component level parasitic loss data in support of modeling and analysis of vehicle-level emissions and fuel economy. 1. SCOPE This SAE Recommended Practice covers transfer cases used in passenger car and light truck applications. Transfer cases are of t
7、he chain, geared, manually and electronically shifted types although other configurations are possible. The operating points (speeds, temperatures, etc.) were chosen to mirror those of the United States Environmental Protection Agency Vehicle Chassis Dynamometer Driving Schedules (DDS). 1.1 Purpose
8、To provide a common means to consistently measure and quantify the speed-dependent parasitic loss (“spin loss“) characteristics of transfer cases. 2. REFERENCES 2.1 Related Publications The following publications are provided for information purposes only and are not a required part of this SAE Tech
9、nical Report. 2.1.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. SAE J1952 All Wheel Drive Systems Classification SAE J2059 All-Wheel-Drive Drivetrain Schema
10、tic Symbol Standards SAE J2263 Road Load Measurement Using Onboard Anamometry and Coastdown Techniques SAE INTERNATIONAL J2985 Issued FEB2014 Page 2 of 11 2.1.2 Other Publications United States Code of Federal Regulations, Title 40 - Protection of Environment 40 CFR, Part 86 - Control of Emissions f
11、rom New and In-Use Highway Vehicles and Engines 40 CFR 86 United States Environmental Protection Agency, Emission Standards Reference Guide 3. DEFINITIONS 3.1 Transfer Case In a longitudinal mounted drivetrain based vehicle, this term refers to the drive mechanism that distributes power to the front
12、 and rear axles. The transfer case may also contain torque management devices. Externally the transfer case is mechanically connected to the transmission, which provides its input power, and to the front and rear axles via drive shafts, which distribute its output power (as shown schematically in Fi
13、gure 1). Internally, the transfer case mechanically connects the front and rear outputs via chain or gears. Depending on the design, the transfer case may be electronically or manually shifted between two wheel drive (2WD) and all-wheel drive (AWD) modes or it may only have an AWD mode. Transfer cas
14、es may be single or multi-speed depending on the design and application. FIGURE 1 - TRANSFER CASE SCHEMATIC (SHOWN WITH REFERENCES TO VEHICLE POSITION) SAE INTERNATIONAL J2985 Issued FEB2014 Page 3 of 11 3.2 Unit Under Test (UUT) This term and its associated acronym is used to describe the test arti
15、cle (transfer case) undergoing the tests outlined herein. 3.3 Average Skin Temperature (AST) To accurately represent the temperature of the unit under test (UUT), a metric has been developed using the average of PXOWLSOH WKHUPRFRXSOHV 7KLV PHWKRG KDV EHHQ GHPRQVWUDWHG WR DFFXUDWHO UHSUHVHQW WKH LQWH
16、UQDO RYHUDOO FRUH temperature of the UUT and is based on a detailed study using an array of internal and external thermocouples. The thermocouples should EHVROGHUHGWLSWSH LHHSRVHGZLUHVWLS DQGDGKHUHGWRWKHXQLWXVLQJDWKHUPDOOFRQGXFWLYHadhesive to be most representative of the metal temperature. The AST
17、measurement is composed of the arithmetic average readings of seven (7) thermocouples located as follows: 1-4) As close to the outer race of the input and output shaft support bearings as possible (4 total thermocouples) 5) As close to the vent as possible, but not inside the vent 6) Top of transfer
18、 case housing (center/middle of main input shaft) 7) Top of transfer case above torque multiplying gear set (for multi-speed units; for single speed, as close as possible to WKHWUDQVIHUJHDU- belt/chain/gear - which drives the front output shaft) A pictorial example of sample locations is shown in Fi
19、gure 2. FIGURE 2 - AVERAGE SKIN TEMPERATURE SAMPLE LOCATIONS 1= Input Shaft; 2 = Prim. Shaft Rear; 3 = Sec. Shaft Front; 4 = Sec. Shaft Rear; 5 = Vent; 6 = Top/Mid, 7 = Ring Gear/Top SAE INTERNATIONAL J2985 Issued FEB2014 Page 4 of 11 3.4 Sump Temperature A thermocouple is installed in the drain plu
20、g (as shown in Figure 3) of the UUT to record the temperature of the oil within the test unit. This temperature is used in conjunction with the AST to establish the temperature state of the UUT. (NOTE: Sump temperature is not included in the AST calculation/definition defined above in Section 3.3.)
21、FIGURE 3 - SUMP TEMPERATURE VIA DRAIN PLUG 3.5 Temperature-Controlled Chamber In order to conduct the testing outlined in Section 4, a suitable temperature-controlled chamber must be used. The chamber should be capable of controlling the transfer case temperature without directly conditioning the oi
22、l inside the transfer case (i.e., via convection). The method used should minimize the creation of localized hot or cold spots on the transfer case (a heat gun blowing directly on the UUT, for example). The chamber should be capable of achieving an average skin temperature (AST) in the range of -7 C
23、 (20 F) to +65 C (150 F), 1 C. Note, to achieve this range it is likely the chamber will need to be capable of achieving temperatures slightly above and below these target temperatures. Specific design of the chamber is beyond the scope of this specification; however, during the development of this
24、specification, liquid nitrogen (LN2) was utilized to achieve the lower range (-7 C) of the specification. If liquid nitrogen is used, care should be taken to ensure no liquid nitrogen is spilled or splashed directly on the UUT as it could damage the unit. A schematic of the chamber used is shown bel
25、ow in Figure 4 and a photograph of the chamber used is shown in Figure 5. FIGURE 4 - SCHEMATIC OF TEMPERATURE-CONTROLLED CHAMBER Thermocouple extends 3 mm from plug endCirculation FanUpper LN2Cooling LoopLower LN2Cooling LoopForced Air Heat OpeningRelief VentUUT Input AccessSAE INTERNATIONAL J2985 I
26、ssued FEB2014 Page 5 of 11 FIGURE 5 - PHOTOGRAPH OF TEMPERATURE-CONTROLLED CHAMBER 3.6 Soak Time The soak time is defined as the minimum amount of time the UUT must be maintained at target average skin temperature in order to achieve repeatable results. An example of the temperature profile for the
27、temperatures included in the AST (defined above in Section 3.3) is shown below in Figure 6 (note that the offset in temperatures T1 and T5 represents standard measurement variation measurement error, temperature distribution within the cold box, etc. and is further justification for using an AST ins
28、tead of individual temperatures). As noted in the figure, an initial (pre) soak of four (4) hours was used followed by a 45 minute soak; the soak requirements are further outlined in Section 4.3.1.2. Should the available cooling system not be capable of reaching an AST of -7 C 1 C ZLWKLQKRXUVDGGLWLR
29、QDOSUH-VRDNWLPHZLOObe required prior to the 45 min additional soak (at target temperature). FIGURE 6 - 7 C INITIAL SOAK -15-10-50510152025012345Temperature CTime hT1 Input ShaftT2 Prim. ShaftT3 Sec. Shaft FrontT4 Sec. Shaft RearT5 VentT6 Case TopT7 Ring Gear Top4 hrs Cooling Period 45 minComponents
30、of Avg. Skin Temp (AST) -7C +/- 2.5CStarting Temperature = Room TemperatureXXSAE INTERNATIONAL J2985 Issued FEB2014 Page 6 of 11 Figure 7 shows a soak following a completed test run; the AST must be brought back within 1 C of the target test temperature and all components of the AST within 2.5 C, th
31、en an additional 45 minute soak needs to be performed prior to acquiring the next test run. FIGURE 7 - RUN TO RUN SOAK 3.7 Stabilization Time (Inertia Influence) The stabilization time is defined as the minimum amount of time required to hold the input speed constant in order to achieve a representa
32、tive input torque measurement and remove any dynamometer or UUT inertial influence. (Note: The control capability of the dynamometer will likely impact the severity of this influence.) It is important that enough stabilization time passes to remove the inertial influence, but it is equally important
33、 not to remain at any given input speed long enough to cause the AST and/or oil sump temperature to rise significantly as this will distort the measured input torque. Figure 8 shows an example of the influence motor controls and inertia may have on the input torque PHDVXUHPHQW$VQRWHGEHORZDVXLWDEOHZL
34、QGRZVKRXOGEHFKRVHQWREHFHUWDLQWorque is measured/averaged only while the input speed is constant (i.e., not while transitioning). In addition to eliminating the inertial influence, it is important to have the test stand controls configured to minimize the overall time required to complHWHWKHIXOOVWHSS
35、HGVZHHS GHILQHGEHORZLQ6HFWLRQ3.9) data run to minimize the warming of the lubricant and test unit. FIGURE 8 - INERTIA INFLUENCE -12-10-8-6-4-200 102030405060Temperature CTime mT1 Input ShaftT2 Prim. ShaftT3 Sec. Shaft FrontT4 Sec. Shaft RearT5 VentT6 Case TopT7 Ring Gear TopOut of Range 45 minCompon
36、ents of Avg. Skin Temp (AST) -7C +/- 2.5CXX5 10 15Torque TraceSpeed Trace,QHUWLDLQIOXHQFHUHPRYHGEWULPPLQJLQSXWWRUTXHVHFbefore and after speed change and averaging over 5 secondsUtilize Data Without Inertial Influence5 s0.2 s 0.2 sTime sSpeed rpmTorque N-mSAE INTERNATIONAL J2985 Issued FEB2014 Page 7
37、 of 11 3.8 Run-to-Run Repeatability In order to verify representative results are being achieved, it is important to establish reasonable run-to-run repeatability. For a given UUT the run-to-run repeatability under the same temperature/input speed conditions should be within 0.5 N-m. 3.9 Stepped Swe
38、ep Test Series In order to maximize run-to-run repeatability, data is acquired DVDVWHSSHGVZHHSWHVWVHULHVDVVKRZQLQ Figure 9. The stepped sweep test series is defined as a procedure whereby the dynamometer input motor is ramped to the target input speed over a maximum of 2.5 seconds, data is recorded/
39、averaged over 5 seconds (excluding trimming of inertial influence), and the input motor is ramped to the next target input speed (again, over a maximum of 2.5 seconds). It is recommended this process be automated in the test cell control system in order to minimize the total time for the sweep test
40、(which can cause the unit to heat up beyond the target temperature if the sweep takes too long): The total time for each sweep test (including 8 set speeds, 5 seconds of data collection per set speed, 2.5 second ramp times, and 0.2 seconds of data trimming before and after the ramp) should be a maxi
41、mum of 63 seconds. During development of this procedure, utilizing a single stepped sweep test series with automated programming was shown to significantly improve repeatability verses methods that required stopping data acquisition to re-soak the UUT to a target temperature. This was particularly t
42、rue for the -7 C condition, but soak interruptions were also shown to affect the 21 C and 65 C conditions. FIGURE 9 - STEPPED SWEEP TEST SERIES 4. PROCEDURES 4.1 Equipment Requirements Measurements are to be performed on a standard horizontal axis test stand with a motor driving the transfer case in
43、put and a precision torque measurement device mounted between the motor and UUT as shown schematically in Figure 10. (NOTE: If a linkshaft or gear box are utilized, they should be located between the drive motor and input torque meter). The tests outlined in this procedure focus on the 2WD/RWD opera
44、tion mode only and the front/rear outputs should be unloaded and unconstrained (not connected, except during break-in, if required). Ideally, the test bench should have tilt capability in order to conduct the testing with the unit mounted in the as-installed vehicle position/angle (typically 5-7 deg
45、rees off horizontal with the rear output of the transfer case lower than the input; this will more accurately replicate the in-vehicle oil level and flow behavior). Regardless of which method used, the installation angle should be documented in the test report. Temperature control must be via extern
46、al (environmental) conditioning rather than direct conditioning of the oil within the test unit (as described earlier in Section 3.5). Torque and speed capabilities of the test stand are to be appropriately sized for the UUT. A sampling rate greater than or equal to 10 Hz is recommended for data acquisition. The torque meter should be appropriately sized in consideration of the low drag torques (10 N-m) expected and a 012345010002000
