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5、evised 2016-01 Superseding J3047 OCT2015 Recommendation for Acceptable Operating Parameters of Heated Automobile Seats in Order to Mitigate Occupant Injury RATIONALE This is to fix a typographical error in equation 1. 1. SCOPE This recommended practice will promote a temperature and duration guideli
6、ne that mitigates the risk of thermal injuries to the heated seat user. In addition, recommendations are established to indicate to the user when the heater is operating, and warnings that should be included in the vehicle literature. 2. REFERENCES 2.1 Applicable Documents The following publications
7、 form a part of this recommended practice to the extent specified herein. Unless otherwise indicated, the latest issue shall apply. 2.1.1 ASTM Publications Available from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959, Tel: 610-832-9585, www.astm.org ASTM
8、C1055-03 American Society for Testing and Materials Standard Guide for Heated Surface Conditions that Produce Contact Burn Injuries 2.1.2 ISO Publications Copies of these documents are available online at http:/webstore.ansi.org/ ISO 13732-1 Ergonomics of the Thermal Environment - Methods for the As
9、sessment of Human Responses to Contact with Surfaces - Part 1: Hot Surfaces (Sep 1, 2006) SAE INTERNATIONAL J3047 JAN2016 Page 2 of 7 2.1.3 Other Publications Henriques F.C. Jr., 1947, Studies of Thermal Injury. V. The Predictability and the Significance of Thermally Induced Rate Processes Leading t
10、o Irreversible Epidermal Injury, Archives of Pathology 43, 489-502. Moritz, A.R, and Henriques, F.C, Jr., 1947: Studies of Thermal Injury II: The Relative Importance of Time and Surface Temperature in the Cutaneous Burns, American Journal of Pathology, Vol 23, 695-720. Kokate, J.Y., Leland, K.J., He
11、ld, A.M., Hansen, G.L., Kvenn, G.L., Johnson, B.A., Wilke, M.S., Sparrow, E.M., and Iaizzo, P.A.: Temperature-Modulated Pressure Ulcers: A Porcine Model, Arch Phys Med Rehabil, Vol 76, July 1995, 666-673 3. DEFINITIONS 3.1 HEATED SEAT SYSTEM A system consisting of a complete seat, heater source, hea
12、ter controls, which may contain an electronic control unit (ECU), relay, etc., which provide a heated seat option to the vehicle occupants. 3.2 MAXIMUM OPERATING TEMPERATURE The maximum temperature reached for either steady state operation or during heater ramp up, measured at the seat surface which
13、 is in full contact with an occupant or an equivalent test specimen. 4. ESTABLISHING MAXIMUM OPERATING TEMPERATURE AND DURATION 4.1 Maximum Operating Temperature Setting The maximum operating temperature for a seat heater measured at the seat surface over a given time should be set to operate below
14、the limit described in Equation 1: TB = 45.652 x t-0.0222 (Eq. 1) Where: t is time in hours Equation 1: Threshold temperature (C) for first degree burn This is based on the experimental data for a first degree burn as described in Appendix A. This equation is graphically illustrated in Figure 1: SAE
15、 INTERNATIONAL J3047 JAN2016 Page 3 of 7 Figure 1 - Time/temperature limit for first degree burn threshold, extrapolated for longer durations At long time exposures, this matches the ISO 13732-1 limit of setting 43 C as a maximum operating temperature setting. At shorter time exposures, this tempera
16、ture can be increased; for example, to improve customer comfort in a cold cabin at vehicle start up. This equation results in temperature limits that are slightly lower than the experimental data. This difference is larger in the first two minutes, leading to a conservative result compared to the ex
17、perimental data. Refer to Appendix A for a full comparison. Equation 1 defines a single maximum operating temperature exposure limit. If the limit as described by Equation 1 is reached, a heater should then reduce this temperature to 43 C or lower. Alternatively, extra margin may be specified to the
18、 limit of Equation 1, which would allow the heater to step down over time while mitigating the risk of an accumulated heat low temperature burn. If one elects to pursue this type of design, it needs to be conducted with an understanding of how to adjust the temperature over time to address the effec
19、ts of accumulated heat. 4.2 Temperature Setting Control There are several possible methods to limit the heater performance into this area under the limit curve. For example, an ECU within the heater system could receive temperature feedback via a thermostat or temperature sensor and limit the heater
20、 power. A simpler method is to set the maximum operating temperature to 43 C, controlled by a thermostat. Alternatively, the heater controller may have an auto adjustment feature that turns the heater down or off before it exceeds the limit curve threshold temperature. The maximum operating temperat
21、ure of the seat heater should account for variation within the performance of the heater. 5. INDICATION ALERT TO USER Each seating position equipped with a seat heater shall have a clear indication of the operating status of the seat heater that is visible to that seat occupant when the occupant is
22、in a normal seating position. SAE INTERNATIONAL J3047 JAN2016 Page 4 of 7 6. VEHICLE LITERATURE The vehicle owners manual or literature provided with the vehicle should describe heated seat operation and also include a warning for heated seat occupants with compromised senses, for example, paraplegi
23、cs or diabetics. 7. TEST PROCEDURE Each manufacturer should determine the best test method for evaluation of their heated seat system. The test procedure should include the measurement of variation to ensure that the maximum operating temperature of the seat heater falls within the recommended limit
24、s of section 4.1. As the original experimental data was measured at the surface of the test subjects skin, manufacturers should take this into account when devising their test method (Moritz and Henriques, Studies of Thermal Injury II, pages 696-698). 8. NOTES 8.1 Revision Indicator A change bar (l)
25、 located in the left margin is for the convenience of the user in locating areas where technical revisions, not editorial changes, have been made to the previous issue of this document. An (R) symbol to the left of the document title indicates a complete revision of the document, including technical
26、 revisions. Change bars and (R) are not used in original publications, nor in documents that contain editorial changes only. PREPARED BY THE SAE HEATED SEATS STANDARDS COMMITTEE SAE INTERNATIONAL J3047 JAN2016 Page 5 of 7 APPENDIX A - ESTABLISHING MAXIMUM OPERATING TEMPERATURE AND DURATION. The medi
27、cal definition of a burn is: First degree burn A superficial burn in which damage is limited to the outer layer of skin in the epidermis and is marked by redness, tenderness, and mild pain. Blisters do not form, and the burn heals spontaneously without scar formation. Second degree burn A burn that
28、damages all of the epidermal and some superficial dermal tissues but does not damage the lower-lying hair follicles, sweat, or sebaceous glands. The burn is painful and red; local blood flow is maintained; blisters form; and wounds heal spontaneously but sometimes with a scar. Third degree burn A bu
29、rn that extends through the full thickness of the skin and subcutaneous tissues beneath the dermis. The burn leaves skin with a pale, brown, gray, or blackened appearance. Local blood flow is terminated. The burn is painless because it destroys nerves in the skin. Scar formation and contractures are
30、 likely complications that often require grafting. (adapted from Tabers Cyclopedic Medical Dictionary, F.A. Davis Co., Philadelphia) This committees recommendation deals with preventing first degree burns. By preventing this level of burn, more severe burns are also avoided. The fundamental research
31、 for the effect of hot temperatures on human skin was performed using human experiments and mathematical modeling by A.R. Moritz and F.C. Henriques. They established 44 C as the minimum temperature needed to cause a first degree contact burn on bare human skin. This data was tabulated in Henriquess
32、Studies of Thermal Injury V on page 494: Table A1 - Exposure time and skin surface temperature for first degree burn thresholds based on experimental research, compared to the recommended practices calculated results Henriques Experimental data Equation 1 Calculated Data delta Time (hr) Time (min) T
33、ime (s) Temp C 0.000 0.0 1.0 65 54.8 -10.2 0.001 0.0 2.6 60 53.6 -6.4 0.002 0.1 8.3 56 52.2 -3.8 0.005 0.3 18.0 54 51.4 -2.6 0.012 0.7 44.0 52 50.3 -1.7 0.021 1.3 75.0 51 49.7 -1.3 0.036 2.2 130.0 50 49.1 -0.9 0.072 4.3 260.0 49 48.4 -0.6 0.156 9.3 560.0 48 47.6 -0.4 0.361 21.7 1,300.0 47 46.7 -0.3
34、0.833 50.0 3,000.0 46 45.8 -0.2 2.000 120.0 7,200.0 45 45.0 0.0 5.000 300.0 18,000.0 44 44.0 0.0 6.944 416.7 25,000.0 43.7 n/a 8.000 480.0 28,800.0 43.6 n/a 10.000 600.0 36,000.0 43.4 n/a 12.000 720.0 43,200.0 43.2 n/a (Henriques, F.C., 1947, Studies of Thermal Injury V: The Predictability and the S
35、ignificance of Thermally Induced Rate Processes Leading to Irreversible Epidermal Injury, Arch Pathol 23, 489-502) SAE INTERNATIONAL J3047 JAN2016 Page 6 of 7 The equation 1 calculated data results in temperatures that are slightly lower than the Henriques experimental data. Equation 1 should not be
36、 used for exposure times of less than two minutes (orange shaded area), due to the large difference to the experimental data in this range. Note, however, that using Equation 1 will always give a conservative prediction of injury causation conditions. At temperatures less than or equal to 43 C, Mori
37、tz and Henriques found it is not possible to sustain a burn injury (Studies of Thermal Injury II, pages 712-713). Other burn research, such as that done by Alice Stoll, deals with radiation burns which are not directly applicable to automobile heated seats. SAE INTERNATIONAL J3047 JAN2016 Page 7 of
38、7 APPENDIX B - PRESSURE INJURIES COMPARED TO THERMAL BURNS At temperatures less than or equal to 43 C, it is not possible to sustain a burn injury. However, pressure injuries are possible at lower temperatures, and they may be difficult to distinguish from a burn injury in clinical manifestation. Pr
39、essure injuries occur by an entirely different physiological mechanism than do burn injuries, even though they may result in a similar outward appearance to a treating physician. Heat may also increase the occurrence of pressure injuries. (Kokate, et al, Temperature-Modulated Pressure Ulcers: A Porcine Model, p 673) This recommended practice only considers burn injuries, not pressure injuries.
