一(yi)辆特(te)斯(si)拉Model S正(zheng)在(zai)TRC的湿滑地面(mian)车辆动力测试区域进行测试。(Sebastian Blanco)
TRP维修大楼(lou)内的亨特(te)对准升降机。(Sebastian Blanco)
Smithers的TRP跑道系统经理(li)Taylor Floyd(Sebastian Blanco)
TRC的湿滑地面车(che)辆动力测试区(qu)域(yu)是一个800*800英尺(244*244 米)的赛道,包括一个水(shui)深为1.75至(zhi)2.25毫米(0.07至(zhi)0.09 英寸)的公路赛道。(Discount Tire)
TRC的越野赛(sai)道全长超过4英里(li)(6公里(li)),由硬土、岩石、沙子(zi)和砾石铺(pu)成,设(she)有弯道、爬(pa)坡和其他障碍。(Discount Tire)
在湿滑条件下测(ce)试(shi)(shi)TRC的30度光滑混凝土斜坡。Discount Tire表示,这一(yi)特(te)性(xing)非常适合耐(nai)久(jiu)性(xing)和主观牵引力(li)测(ce)试(shi)(shi)。(Discount Tire)
如何将轮胎测试数据(ju)转(zhuan)化为非工程专(zhuan)业人士也能理(li)解的信(xin)息(xi)?
Discount Tire公司的首席产品与技术官John Baldwin告诉SAE,在Treadwell研究园(Treadwell Research Park)开展的所有工程工作中,有一种神奇的方法可将大量测试数据转化为非工程师也能理解的实用信息。
TRP是Discount Tire的数据(ju)(ju)生(sheng)(sheng)成中(zhong)心,该公司的Treadwell轮(lun)胎选购(gou)指(zhi)南背后的算法(fa),使(shi)用的正是这(zhei)里生(sheng)(sheng)成的数据(ju)(ju)。该工(gong)具采(cai)用五星制评(ping)分体系,可为轮(lun)胎选购(gou)者提供(gong)个性(xing)化且简明易懂的产(chan)品(pin)推(tui)荐,消费(fei)者可在应用程序、网站和线下门店使(shi)用该工(gong)具。Baldwin 表(biao)示,多年来(lai),Discount Tire及其合作伙伴测试了超过2万(wan)只(zhi)轮(lun)胎,涵盖500到1000种(zhong)不同(tong)类型,包(bao)括衍生(sheng)(sheng)和升级产(chan)品(pin)。
然(ran)而,测试一款轮(lun)(lun)胎(tai)并得出其滚动阻力系数(shu)为8.2是一回事,向店里的轮(lun)(lun)胎(tai)选购(gou)者解释这一数(shu)据(ju)则是另一回事。
“应该如何告知客户(hu),一只轮胎不(bu)错(cuo)但不(bu)够出色?我(wo)们(men)(men)的(de)方法(fa)(fa)是(shi)给它打三星(xing),或是(shi)三星(xing)半的(de)评分,”他说(shuo),“这只是(shi)借鉴(jian)了(le)一些行(xing)业中已(yi)有(you)的(de)做法(fa)(fa)。我(wo)们(men)(men)会在后(hou)台对数据进行(xing)分级。例如,X到Y是(shi)五星(xing),Y到Z是(shi)四(si)星(xing)半。我(wo)们(men)(men)的(de)算法(fa)(fa)使用真实数据,希望能(neng)让客户(hu)无需成为轮胎方面的(de)专(zhuan)家就可理解专(zhuan)业信息。”
据Baldwin介绍(shao),为了(le)实现这(zhei)一目(mu)标,本身(shen)不生产轮胎(tai)、只负责(ze)销售的(de)Discount Tire收购(gou)了(le)一家轮胎(tai)测(ce)试(shi)机构。这(zhei)个占地900英亩的(de)测(ce)试(shi)场地位于(yu)德克萨斯州(zhou)圣安(an)东尼奥附(fu)近,之(zhi)前由Cooper Tire & Rubber公司所有,2021年被固特异轮胎(tai)收购(gou)。由于(yu)固特异在德克萨斯州(zhou)已经(jing)有了(le)一个测(ce)试(shi)跑道,Discount Tire获得(de)了(le)收购(gou)TRP的(de)机会。
Discount Tire并不参与TRP的(de)日常(chang)运营,而是雇(gu)佣轮(lun)胎(tai)(tai)测(ce)试(shi)公(gong)司Smithers作(zuo)为独立(li)第(di)三方,每年(nian)使用该设施约120至(zhi)150天。此外,一些轮(lun)胎(tai)(tai)OEM在(zai)TRP的(de)三个附(fu)属(shu)建(jian)筑中长租(zu)了(le)固定空(kong)间。TRP的(de)主楼包(bao)含办公(gong)区和一个配有五个车辆升降机的(de)车库,而附(fu)近的(de)一座维修用楼则存(cun)放了(le)轮(lun)胎(tai)(tai)和Matteuzzi胎(tai)(tai)面打磨机等工具(ju)。
当我(wo)们乘坐的(de)Wrangler停(ting)留(liu)在(zai)30度(du)坡道上(shang)时(shi), Floyd解释道:“在(zai)测试三(san)种不同的(de)胶料时(shi),我(wo)们会感(gan)受(shou)到三(san)种不同的(de)‘抓(zhua)地感(gan)’。在(zai)进行这类测试时(shi),我(wo)们不希望依赖动能(neng),因(yin)为动能(neng)是(shi)一(yi)个很(hen)难(nan)控制的(de)变量。如果(guo)尽(jin)可(ke)(ke)能(neng)缓慢且稳(wen)定(ding)地爬坡,就(jiu)能(neng)使(shi)测试条件(jian)保持高度(du)一(yi)致。我(wo)们可(ke)(ke)以把不一(yi)致的(de)因(yin)素移除(chu),并尽(jin)可(ke)(ke)能(neng)添加一(yi)致的(de)因(yin)素。”
“每种胶(jiao)料、每种设计在(zai)(zai)这些极小的(de)接触面上弯曲(qu)方式(shi)都(dou)各不相同,”他说。“硅(gui)基胶(jiao)料可能在(zai)(zai)胶(jiao)料面的(de)边(bian)缘处含有硅(gui)颗粒(li),这有助于(yu)其抓(zhua)住(zhu)接触表(biao)面上的(de)微小粗糙点。胶(jiao)料在(zai)(zai)轮胎边(bian)缘0.1毫(hao)米(mi)范围(wei)内的(de)弯曲(qu)方式(shi),是(shi)最能体现(xian)胶(jiao)料性能之处。嵌在(zai)(zai)橡胶(jiao)表(biao)面的(de)硅(gui)颗粒(li)是(shi)否足够牢固(gu),能提供牵引力,还是(shi)会(hui)从橡胶(jiao)表(biao)面滑出?胶(jiao)料在(zai)(zai)开始撕裂之前能否保持(chi)自身结构?这些都(dou)是(shi)需(xu)要测试的(de)问(wen)题。”
“从技术上(shang)讲,轮胎不可能总是(shi)全新(xin)的(de)(de),”他说。“一旦(dan)上(shang)路,轮胎的(de)(de)磨损就(jiu)马上(shang)开始了。因此,轮胎性能存在一个逐渐(jian)改变(bian)的(de)(de)过程。我们已经让消费者意识到,应该考虑轮胎在整个生命(ming)周期(qi)中的(de)(de)性能,而这是(shi)以磨损程度来衡量的(de)(de)。”
For all the engineering that takes place at the Treadwell Research Park (TRP), Discount Tire’s chief product and technical officer John Baldwin told SAE Media that there’s actually something akin to magic in the way giga-reams of test data are converted into information non-engineers can usefully understand.
TRP is where Discount Tire generates data used by the algorithms behind its Treadwell tire shopping guide. The consumer-facing Treadwell tool, available in an app, a website and in stores, provides tire shoppers with personalized, simple-to-understand recommendations that are mostly based on a five-star scale. Discount Tire and its partners have tested over 20,000 SKUs, representing 500 to 1000 different types of tires over the years, Baldwin said, including variants and updates. Testing a tire to discover it has an 8.2 rolling resistance coefficient is one thing. The trick is finding a way to explain it to someone standing in a tire shop.
“How do I say that that’s an okay tire but not a great tire? Three. Or three and a half,” he said. “We just latched on to what the world’s already doing. Behind the scenes, we’ll have it, in that case, bucketed. X to Y is a five-star, Y to Z is four and a half, those kind of things. The algorithm actually does take the real data. The expectation is our customers are not going to become experts on tires.”
To do that, Discount Tire - which does not manufacture tires, it just sells them - bought itself a tire testing facility. The 900-acre site near San Antonio, Texas, was previously owned by Cooper Tire & Rubber Company before it was purchased by Goodyear in 2021. Since the company already has a test track in Texas, Goodyear offered Discount Tire the opportunity to buy the TRP, Baldwin said.
Discount Tire is not involved in TRP's day-to-day operations. Instead, tire testing company Smithers acts as an independent third party that uses the facility around 120-150 days a year. Some tire OEMs – Discount Tire would not name them – rent permanent space at TRP in the three outbuildings. The main building houses offices and a garage with five vehicle lifts, while a nearby maintenance building holds stacks of tires and a Matteuzzi tire buffer, among other tools.
Test for yourself
During a recent media day, Discount Tire opened TRP to SAE Media and other outlets. We were able to participate in tests similar to what the Smithers engineers do there. That meant feeling the way Goodyear Assurance Max Life All-seasons pulled differently from Michelin Pilot Sport S summer tires around the curve of the 2-mile oval at 65 mph (105 km/h). We tested those same EVs and two BMW M5s on the 15-acre wet track with a one-degree slope and a Lotus Emira Turbo First Edition through some cones before running a Jeep Wrangler Rubicon through the off-road course. While we were stopped on the polished concrete hill, Smithers’ TRP track systems manager, Taylor Floyd, told SAE Media why this is a great way to test tire compounds.
“If you’re testing three different compounds, you’re gonna have three different ‘feels’ of how easy it is,” he said as we sat in the Wrangler angled at 30 degrees. “When you’re doing this type of testing, you don’t want the momentum because that’s already a variable that is really hard to control. If you go up there as slowly and as steadily as possible, you can be the most consistent. You can take something inconsistent and try to add whatever consistency is possible.”
The polished concrete hill test is where drivers evaluate how much throttle they can add before the vehicle starts up again if the vehicle loses traction at any corner, and if the driver needs to engage a differential lock or something similar to complete the climb. Floyd said the usual expectation is that 2WD will get the vehicle up the slope but will not be able to restart forward momentum once it comes to a complete stop. Restarting up the hill is the moment of truth. What the drivers are trying to feel with this test, he said, is how well the roughnesses of the rubber surface and the polished concrete surface play together at the tiniest of scales to either stick or slip.
“Each compound, each design is going to have a different way it flexes at that really small interaction face,” he said. “A silica-based compound may have silica pieces at the edge of the compound face, and that helps grab onto the small roughness of the surface itself. How the compound flexes in that 10th-of-a-millimeter range at the edge of the tire, that’s where the compound is having the most effect. Is the little piece of silica stuck in the rubber surface well enough to provide traction, or is it going to slip out? How is the compound holding on to itself before it starts to tear apart?”
Subjective/objective
Baldwin, a polymer scientist who previously worked at Ford, said the Smithers test drivers use the SAE J1060 10-point subjective rating test to turn feelings into numbers.
“The drivers all follow the SAE rules for that,” he said. “A difference of one means a professional driver may notice the difference, but your average driver wouldn’t. Two is normal people, and three is a huge difference, which translates into half, one and one and a half stars. Let’s say out on the wet, they might have ten categories that they’re rating. There’s the lap time, which I consider objective, but then there’s breaking, which is subjective out there, cornering, steering, response, linearity, transition, all of those things that then they’re putting ratings on. Then they add it up, and they come up with [a score] out of 10 points, and we turn that into the five stars. We might be stylizing it when we show it, but the actual number behind the scenes is whatever the driver comes up with. That’s the number we use.”
Baldwin said the automotive industry has been dealing with these sorts of subjective reviews for a century, and one of Treadwell’s solutions is the use of control tires to help drivers find the baseline each time. These are usually represented by a standard Michelin tire for the application at hand, but “it doesn’t mean they’re the best,” Baldwin said; they’re just the most consistent. These control tires are usually so reliable that Smithers’ drivers have been able to identify manufacturing problems that Discount Tire has then reported back to the tire OEM.
“We re-audit tires too,” he said, to make sure nothing’s changed. “Usually, we would know, but not always. So when we get different numbers than we did a year ago, we would call the manufacturer and go, ‘Hey, what’s up?’ What will happen is we’ll report that in Treadwell. This isn’t about history. This is about today. Someone’s buying tires today. So we want to help them make their decision. We want Treadwell to rank with what the product is today, not what it was a year ago.”
Treadwell also tests worn tires, using that Matteuzzi tire buffer with diamond-encrusted blades and other surfaces to wear them down to 4/32nds before sending them on a trailer test that’s similar to the European R117 wet testing protocol. This test requires only one buffed tire, but Baldwin said that when the engineers were developing the test, they had to correlate between the on-vehicle tires and the machine, but the results are now solid. Reliable data means Treadwell is itself reliable, Baldwin said.
“If you think about it, technically, nobody drives on new tires,” he said. “They’re wearing right away. So there’s this whole gradient of change. We’ve driven an awareness that we should be thinking about the performance of your tire through its life and its life as being defined as wear.”
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