SAE J 2848-3-2012 Tire Pressure Systems - Management (CTIS) Type For Medium and Heavy Duty Highway Vehicles.pdf

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5、essure Systems - Management (CTIS) Type For Medium and Heavy Duty Highway Vehicles RATIONALEWithin the medium and heavy-duty vehicle industry, the equipment supplier community has responded to the need to manage inflation pressure for greater vehicle operational performance when transitioning from i

6、mproved roadways to unimproved roadways and back, by developing onboard adjustable tire pressure systems. The central tire inflation system (CTIS) is one such system. Through a CTIS, the vehicle driver from the cab position is capable of selecting a pressure level based on the ground flotation condi

7、tions, and the vehicle load, for uninterrupted operations. Because operators will expect these systems to provide the selected level of pressure and to maintain that level of pressure especially as the vehicle returns to highway operations, it is important that all marketed systems respond with a mi

8、nimum level of performance to assure continued in-service safety.In the “off-road“ or unimproved roadway environment, the driver typically will operate at a reduced vehicle speed and may choose a reduced tire inflation pressure. Under these conditions, it is important to maintain a balance between t

9、he tires flotation performance at high deflection and the tires durability. These characteristics are particular to each tire manufacturers product, and therefore it is not practical to define one universal set of operating criteria nor a singular limiting threshold for the off-road environment. At

10、the same time, when these vehicles return to highway operations, it is expected that tire pressure systems of this category, having survived the harsh environments to which they were exposed, will be able to bring the tires inflation pressure back to the specified highway pressure level, and maintai

11、n it. For both SAE document SAE J2848/1 and SAE J2848/2, the system performance and communications to the driver functions have been made coherent and consistent. Under this document, it is essential that the driver communications and performance thresholds, especially when operating to highways con

12、ditions, also be consistent with the document series. Each management system must still keep the driver informed of the status of the pressure level and make him aware when the system installed is no longer performing its intended function. This document captures the attributes of pressure managemen

13、t systems while retaining the alerts and warnings so vitally important to the driver.SAE J2848-3 Issued FEB2012 Page 2 of 16 TABLE OF CONTENTS 1. SCOPE 32. PURPOSE . 32.1 Purpose . 33. REFERENCES 43.1 Applicable Documents 43.1.1 SAE Publications . 43.1.2 ATA Publication . 43.1.3 FEDERAL PUBLICATIONS

14、 43.2 Related Publications . 53.2.1 SAE Publications . 53.2.2 ASTM International Publication . 53.2.3 Federal Publications . 53.2.4 Tire and Rim Association Publication . 63.2.5 ETRTO Publication . 63.2.6 JATMA Publication 63.2.7 ISO PUBLICATION . 64. DEFINITIONS . 65. SYMBOLS AND ABBREVIATIONS 86.

15、TIRE PRESSURE SYSTEMS MANAGEMENT (CTIS) TYPE . 86.1 Applications the necessary clearance must be available to install chains to each tire/wheel assembly.6.1.10 If used, the wired or wireless communication link between a power unit and trailer(s), should perform to the guidelines delineated in SAE J2

16、848-1. 6.1.11 If used, the link between a wireless pressure sensor and its receiving module should perform to the guidelines of SAE J2848-1.6.1.12 The vehicle SSP, or reference pressure, is determined in cooperation with the vehicle OEM or specialty manufacturer and the tire manufacturer, based on t

17、he vehicle capacity, the maximum applied axle or wheel position loads, and operating conditions. For reference purposes only, an industry accepted method for determining the appropriate specified service pressure has been documented in the American Trucking Associations TMC RP-235: Guidelines for Ti

18、re Inflation Pressure Maintenance.6.1.13 The minimum service pressure is determined in cooperation with the vehicle operator, the tire pressure system manufacturer, and the tire manufacturer, based on the tires and/or wheels capacity to perform under the reduced pressure conditions. Custom settings

19、may be required for each application due to differences in tire sizes, loading, absence/presence of “bead locks” (or similar), and sidewall flexibility. Bead locks or similar features are highly recommended, but not mandatory. SAE J2848-3 Issued FEB2012 Page 10 of 16 6.2 General System Requirements

20、6.2.1 Management Function 6.2.1.1 The CTIS is a vehicle installed system 1) which can be initialized and managed by the vehicle driver for its operational pressure set point in support of an array of off-highway operational conditions, vehicle stationary or rolling, and 2) which monitors and maintai

21、ns the tire inflation pressure to the pressure set point while operating off-highway and to the vehicle SSP while operating on-highway. The system is therefore one which has inflate and deflate capabilities, as well as maintenance capabilities.6.2.1.2 For CTIS, the management of the TPSP can be achi

22、eved using either mechanical or electronic controller(s).6.2.1.3 With the CTIS, different combinations of vehicle load, speed, and tire pressure can be realized outside the acceptable norms for the vehicle configuration under highway operations. Accordingly, the CTIS must be capable of automatically

23、 defaulting back to the appropriate TPSP whenever a service threshold has been exceeded (i.e., vehicle speed), and must be capable of defaulting back to the vehicles minimum TPSP should the operator erroneously call for a lower pressure value. 6.2.1.4 The CTIS should be capable of deflating or infla

24、ting each tire/wheel assembly by axle grouping steer, drive, lift, dolly, or trailer to the selected inflation pressure set point, without negative effects to any other air-powered systems or accessories on each vehicle so equipped.6.2.1.5 System safeguards must be included in the system design with

25、 regard to the controller and/or sensors to prevent the operator or unauthorized personnel from reducing pressure below the specified minimum pressure, or disengaging the systems ability to select and restore pressure to an appropriate pressure set point. Should the inflate/deflate function be alter

26、ed or the maintenance functions be disabled by error or through tampering, the CTIS should provide to the driver an indication that the system thresholds have been exceeded.6.2.1.6 The CTIS should contain a valve(s) - 1) which, by wheel position, are capable of isolating the CTIS function from a rap

27、id pressure loss assembly, and from a tire/wheel assembly during the action of tire/wheel change-out, 2) which can be cycled during the change of the TPSP to facilitate deflation, 3) which is capable of isolating the air brake system reservoir (where appropriate) from the CTIS function to meet the c

28、riteria of 49 CFR Part 393-Subpart C, 49 CFR Part 571.121, and 49 CFR Part 393.207(f), and 4) with sufficient safeguards to prevent back flow into the applicable truck or bus, prime mover (tractor), and/or trailer vehicle air system.6.2.2 Maintenance Function 6.2.2.1 The CTIS is a system, once the o

29、perational pressure set point has been established and the system enters the maintenance mode, which is sensor activated by a demand for compressed air, vehicle rolling or vehicle stationary.6.2.2.2 The CTIS automatically maintains the tires inflation pressure by axle set (steer, drive, lift, dolly,

30、 or trailer) without the intervention or input of the operator, to the selected inflation pressure set point, governed by the systems defined thresholds.6.2.2.3 The CTIS when functioning at the vehicle SSP level, will maintain the tire inflation pressure to the SSP defined for each axle set.6.2.2.4

31、The CTIS should be capable of maintaining the pressure level relative to the selected TPSP. 6.3 Advanced System Requirements Should the installed CTIS be a full featured electronic system (sensor within every wheel assembly initiating a re-inflation action, communication on the dashboard of the ongo

32、ing status of the monitoring system, wireless communications, etc.), refer to SAE J2848/1 for the associated system functions, measurement metrics, and testing methodologies. SAE J2848-3 Issued FEB2012 Page 11 of 16 6.4 Component Performance Requirements Valves, Sensors, Regulators, Control Modules,

33、 etc. 6.4.1 ENVIRONMENTAL It is the intent that electronic device(s) and mechanical components that are mounted in/on the tire/wheel components or on the vehicle should be sufficiently robust, with typical design safety factors, and hardened by design to be capable of successfully completing all the

34、 tests thermal cycling, thermal shock, humidity, altitude, mechanical shock, drop, mechanical vibration, and combinations of these conditions.The recommended test method for these conditions is defined in SAE J1455. The functionality of the device(s) under test (DUT) should be verified before and af

35、ter testing. Additionally, each DUT should be visually inspected for damage before and after testing. Unless otherwise specified, each DUT must be at ambient atmospheric pressure, relative humidity, and temperature for each test. As these systems are inflate/ deflate capable, that is expelling compr

36、essed air and drawing in atmospheric air for compression and transfer throughout the system, the quality of the air is critical to the longevity and reliability of a tire pressure management system. The quality of the air must be considered during both cycles during intake, moisture content, and sol

37、ids content are critical; during evacuation, the backwash of oils or lubricants, moisture, and desiccants must be eliminated. Therefore the following support systems must be included -a) Use of an air filter/separator is obligatory in that ambient air-borne and compressor oil blow-by contaminates mu

38、st be eliminated or at least minimized.b) Not only moisture/water and the “normal” airborne pollution must be presumed present, but considerations must be made for seasonal contaminates, such as anti-icing agents, pressurized vehicle washing solutions, as well as contaminates observed from roadside

39、and on-site construction activities.c) Position all vent port(s) above any anticipated water levels and avoid direct splashing. 6.4.2 CORROSION The identification of potential physical contaminates, and the mitigation/ elimination of their corrosive effects is critical toboth performance and longevi

40、ty of all tire pressure systems and related hardware. For inflate/ deflate systems, the introduction of these contaminates almost assures subsequent TPMS component and/or system failures due to corrosion and/or clogging of air lines, valves, and ports. Depending on system type, the design and perfor

41、mance of the system components must be addressed in regards to potential system contaminants: for example, power connections; sensing units; component attachment points/locations; inflation supply and source, and check valves. The recommended test methodology for physical contaminates is to apply th

42、e laboratory conditions for corrosive events and cycles, and the chemical mixtures (solutions) as defined in SAE J2721 - Recommended Corrosion Test Methods for Commercial Vehicle Components. 6.4.3 System Design Pressure Capacity The CTIS & components should be tested for proof pressures in accordanc

43、e with federal regulatory requirements and/or industry adopted standards, as appropriate. Testing of the system and components must be made without tires for safety reasons.SAE J2848-3 Issued FEB2012 Page 12 of 16 7. TIRE PRESSURE MANAGEMENT SYSTEM - HMI COMMUNICATIONS & PERFORMANCE THRESHOLDS Each

44、tire pressure management system should employ a design-for-use approach to make its operation self-directed. In other words, the human-machine-interface envelope should require as little operator inputs as may be economically viable within state-of-the-art technology, in order to mitigate or elimina

45、te the potential for intentional and unintentional errors and/or vehicle operator/maintainer-induced damage.7.1 System HMI Characteristics 7.1.1 TPSP communication: The CTIS must be capable of indicating to the driver the TPSP reference which the system is holding on a continuing basis, as well as a

46、n indication that the system is transitioning from one TPSP to another. These communications must be made on the dash board, in full view of the driver, visible both day and night.7.1.2 Low Pressure Warnings communication: The CTIS should be capable of communicating to the driver, andcontinue to com

47、municate this warning until the TPSP has been restored following a low pressure condition. 7.1.3 Malfunction Warning communication: The CTIS should be capable of communicating to the driver a warning that the system is no longer capable of responding to set point changes, nor able to restore lost in

48、flation gas in low pressure assemblies. 7.1.4 A single driver warning device is desirable for power unit and trailer(s), however, lacking such an arrangement, each additional unit (trailer or dolly) should have at least an external warning device visible to the driver.7.1.5 The minimum configuration

49、 of the device for communicating an indication to the driver or a warning to the driver should be a panel with optical telltale(s). The function, sequence, and position of these telltales on a display panel should be determined by the system manufacturer, and documented in the operators manual. Regardless of the design solution, the telltale must illuminate whenever the system is not at rest, i.e., flowing or attempti