美国交通部高速公路交通安全管理局(NHTSA)响应美国TREAD (交通召回提升，可查性及记录) 法令的强制要求，制定了要求机动车辆安装TPMS的新联邦机动车辆安全标准， 对TPMS从安装实施， 产品功能结构到性能指标都做了具体规定。此一针对TPMS的新的安全标准是在广泛征求整车厂，TPMS制造商，轮胎厂及各种行业协会意见的基础上， 经过多次修订而最后确立的。此法令几易其稿， 于2005年四月八号最后颁布生效。 法令要求从2005年十月五号开始新出厂的重量在一万磅以下的机动车辆， 即载客小轿车和轻型车(轴上有双轮的除外)要按进度分期逐步配备TPMS。 也即从2005年10月5号到2006年8月31号， 20%新下线的车必须配备TPMS， 从2006年9月1号到2007年8月31号要到达70%， 2008年9月1号前要保证100%全部安装。
● 此法令对TPMS的各项指标提出了具体要求， 并在此法令的附加说明中做了进一步论述， 其基本要求引述， 翻译如下：
S4.2 TPMS detection requirements. The tire pressure monitoring system must:
TPMS的检测功能的要求， 轮胎气压监测系统必须：
(a) Illuminate a low tire pressure warning telltale not more than 20 minutes after the inflation pressure in one or more of the vehicle's tires, up to a total of four tires, is equal to or less than either the pressure 25 percent below the vehicle manufacturer's recommended cold inflation pressure, or the pressure specified in the 3rd column of Table 1 of this standard for the corresponding type of tire, whichever is higher;
在当车辆的任何一个轮胎或多个以至四个轮胎的气压都比汽车制造商所规定的轮胎应充冷气压数值低25%或者更多时,在20分钟之内发出气压不足警示。
(b) Continue to illuminate the low tire pressure warning telltale as long as the pressure in any of the vehicle's tires is equal to or less than the pressure specified in S4.2(a), and the ignition locking system is in the "On" ("Run") position, whether or not the engine is running, or until manually reset in accordance with the vehicle manufacturer's instructions
维持此气压不足的警示状态， 只要汽车任何一个轮胎的气压值还处于上述气压不足的状况下，而且只要一将点火开关设于开启的位置， 不管发动机运行与否。
S4.3
(a) Except as provided in paragraph (b) of this section, each low tire pressure warning telltale must illuminate as a check of lamp function either when the ignition locking system is activated to the "On" ("Run") position when the engine is not running, or when the ignition locking system is in a position between "On" ("Run") and "Start" that is designated by the manufacturer as a check position.
当点火开关一被激活，发动机还没启动时，做为汽车启动前各功能部件指示灯巡检一项功能，低压警示装置必须能激活显示。，下述(b)除外。
(b) The low tire pressure warning telltale need not illuminate when a starter interlock is in operation.
发动机中的启动机装置处与锁止状态时，低压警示装置可不需激活显示。
● 为什么此法令将相关的功能指标定义为"低于轮胎应充冷气压值25%"和"20分钟之内发出气压不足警示"呢？
法令的附加说明对此做了如下解释：
Selecting an appropriate notification threshold level for the TPMS is one of the most fundamental matters to be resolved as part of this rulemaking. It involves balancing the safety benefits of alerting consumers to low tire pressure against the risks of over-alerting them to the point where the warning becomes a nuisance that may be ignored. We believe that the final rule's 25-percent under-inflation detection level strikes the proper balance in this regard.
This testing led the agency to conclude that warnings at less severe conditions will give drivers sufficient time to check and re-inflate their vehicles' tires before the tires experience appreciable damage.
选择适当的报警门限值是制定此标准的最根本的问题之一，在适当的时刻向驾驶者报警提醒无疑会提升行车的安全性；但过于频繁的报警会让使用者感到厌烦，以至麻木不仁，视而不见，最后反而引致更大的风险，所以在两者之间要有个平衡。我们认为25%气压不足的界限值的恰当的。
相关部门所做的试验表明，TPMS在上述气压不足不是很严重的情况下发出报警，驾驶者将会有足够的时间采取响应的矫正措施，避免可能发生的轮胎事故。
As noted in the agency's June 5, 2002 Federal Register notice, TPMSs were not developed to warn the driver of extremely rapid pressure losses that could accompany a vehicle encounter with a road hazard or a tire blowout. According to the tire industry, those types of events account for approximately 15 percent of pressure loss cases. Arguably, a driver would be well aware of the tire problem in those situations, and the TPMS would provide little added benefit. Instead, TPMSs' benefits lie in warning drivers when the pressure in the vehicle's tires is approaching a level at which permanent tire damage could be sustained as a result of heat buildup and tire failure is possible; this low level of inflation pressure generally results from a more measured pressure loss (produced over weeks or months) caused by a slow leak, defective valve, or diffusion. According to the tire industry, approximately 85 percent of all tire pressure losses are slow air losses that occur over hours, weeks, or months of vehicle use.In those cases, a detection time of 20 minutes is not likely to pose a safety risk to the driving public.
TPMS并不是用来监测急速漏气的，这种情况通常是由于轮胎在路面上遇到有害的物质及路况而瞬间破裂发生的。这种情况驾驶者是会马上感知到的，在这种情况下TPMS几乎不起什么作用。按照相关统计，这一类型的漏气方式大约占到轮胎总漏气数的15%。相反地，TPMS是当轮胎的气压下降到某一层面时向驾驶者报警提醒，而气压在下降到这一层面的过程中会因为产生累积很多热量而导致轮胎永久性的破坏和各类轮胎故障的发生，防范此类事故的发生，这便是TPMS的作用与意义所在。这一轮胎低压层面的出现通常是轮胎气压缓慢渗漏的结果，通常经过几个小时， 几礼拜，甚至几个月才出现，这是一个渐进的可感知测算的过程。这一类型的漏气方式大约占到轮胎漏气总数的85%，在这一情况下，在20分钟内向驾驶者发出气压不足的警示并不会带来安全方面的问题。
注: 此法令标准是基于技术中立的原则，在科学合理的基础上，对各项指标的最低要求。 |
