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附 錄
附錄A:
LOW ROLLING RESISTANCE TIRES
According to the report,80% or more of a car’s fuel energy is wasted by friction and other such losses. 1.5 to 4.5% of total gasoline use could be saved if allreplacement tires in use had low rolling resistance. About 237 million replacement tires are sold in the U.S. each year – none has rolling resistance labeling.
1. America’s Fuel Use, Its Impacts,and Opportunities for Savings
The environmental impacts of America’s gasoline use are profound. With over 160 million passenger cars and light trucks on the road, we burn about 126 billion gallons of gasoline per year. Our fuel use continues to rise about 3% annually, propelled by continued increases in total number of vehicles, rising average distance driven per car, and falling average fuel economy.
Today, light-duty vehicles (cars & light trucks) are responsible for about 20% of the nitrogen oxides, 27% of the volatile organic compounds, 51% of the carbon monoxide, and roughly 30% of all the carbon dioxide (the main greenhouse gas) emitted from human activities nationwide. Rising fuel use also has enormous implications for protection of wilderness and public lands (vulnerable to increased exploration), water resources (vulnerable to tanker and pipeline accidents), and national security. So the opportunity to save money and improve environmental quality through fuel use reductions is clear.
One of the most promising opportunities for fuel savings across the entire fleet of existing vehicles is to utilize low rolling resistance tires instead of standard replacement models. This change improves the inherent efficiency of the vehicle, automatically saving fuel over the typical 30,000 to 50,000 mile lifetime of a set of tires.
This report examines the opportunity for saving gasoline through use of improved tire technology and recommends particular tire models for which our initial test data suggest environmental advantages. Its findings are applicable to government and corporate fleet managers as well as individual tire buyers.
2. How Tires Can Reduce Fuel Consumption
According to the National Academy of Sciences, about 80 to 88% of the energy in a vehicle’s gasoline tank is wasted in various thermal, frictional, and standby losses in the engine and exhaust system. This leaves only about 12 to 20% of the potential energy actually converted to vehicle motion. One of the key ways to improve that efficiency is to reduce the rolling resistance of vehicle tires. This is not a measure of a tire’s traction or “grip” on the road surface, but rather simply indicates how easily a tire rolls down the road, minimizing the energy wasted as heat between the tire and the road, within the tire sidewall itself, and between the tire and the rim.
Detailed modeling conducted by the National Renewable Energy Laboratory concluded that a 10% reduction in tire rolling resistance should yield fuel savings of about 1 to 2%, depending on driving conditions and vehicle type. According to research for the California Energy Commission, about 1.5 to 4.5% of total gasoline use could be saved if all replacement tires in use had low rollingresistance. This translates roughly into average savings of up to 30 gallons of gasoline savings per vehicle per year, or from $2.5 to $7.5 billion worth of national average gasoline savings.
As part of their efforts to meet Federal fuel economy standards, automakers routinely specify low rolling resistance tires on their new vehicles. Between 1980 and 1994, the lowest rolling resistance tire models available achieved a 48% reduction in rolling resistance, and have likely continued to improve thereafter. These original equipment (OE) tire models are occasionally available in the replacement tire market, but often only by special order. In general, the tires marketed to the replacement tire market tend to place greater emphasis on longevity and low price, and therefore often have higher rolling resistance than OE tires.
Unfortunately both OE and replacement tires lack any sort of rolling resistance labeling currently, so fleet managers and consumers that wish to buy highly energy-efficient tires when their first set of OE tires wear out have been stymied. Even when tire makers claim that particular replacement models are more fuelefficient than others, they do not always use consistent test methods or independent laboratory data to back up those claims. About 237 million replacement tires are sold in the U.S. each year for cars and light trucks, and none of them provides rolling resistance labeling.
In 2002, the Energy Foundation funded Ecos Consulting to analyze the tire market, select representative models for rolling resistance testing, and work with Green Seal to recommend particular models that perform well while achieving low rolling resistance. Those findings are being published for the first time in this Choose Green Report. Additional background on Ecos Consulting’s key findings can be found in a separate report prepared for the California Energy Commission, available at www.energy.ca.gov/reports/2003- 01-31_600-03-001CRVOL2.PDF.
3. Balancing Tire Resistance and Other Considerations
The manufacture of tires, like other industrial processes, involves material extraction and production, as well as energy consumption and the emission of various pollutants. Each of these manufacturing stages impacts the environment in different ways. However, tires, like a number of other consumer products, are actually responsible for more environmental impacts in their use and ultimate disposition than in their manufacturing. They significantly impact the amount of fuel consumed by the vehicle to which they are attached, leading to global warming emissions as well as local and regional air pollution. They create particulate air pollution in the process of wearing, and they can be a significant solid waste problem if not properly recycled.
An analysis conducted by Italian tire manufacturer Pirelli (Figure 1) revealed the dominance of tire use in overall life-cycle energy consumption. Fully 82% of the lifecycle energy use occurs from the tire’s contribution to vehicle fuel use, compared to roughly 18% associated with obtaining the raw materials and manufacturing the tire itself. Thus, a tire’s rolling resistance is likely to be a larger factor in its life-cycle environmental impact than its composition, longevity, or ultimate fate, though those factors merit consideration as well.
This report places greatest significance on the measured rolling resistance of tires, followed closely by consideration of the tire’s expected longevity and performance characteristics. A tire with high rolling resistance can cause profound environmental impact, even if it capably grips the road and lasts for 80,000 miles. By contrast, a very low rolling resistance tire may not be worth recommending if its lifetime is unusually short or test data indicate that it provides poor traction.
Every tire currently on the market represents a balance between a wide assortment of desired performance characteristics and price (we surveyed tires ranging from $25 to over $200 per tire). Careful balancing of these characteristics can yield not only a high-performing tire, but also one that is better for the environment than others currently available on the market.
4.Rating Tire Rolling Resistance and Related Factors
Rolling resistance has traditionally been measured through an official Society of Automotive Engineers (SAE) test procedure known as J1269. It measures the force required to roll a tire against a dynamometer at a fixed speed of 50 miles per hour. A newer procedure, SAE J2452, promises improved accuracy by assessing rolling resistance at a variety of speeds, but no independent laboratory currently has the capability to conduct such testing in-house. As a result, all of our testing was conducted at a single independent laboratory according to SAE J1269.
The highest and lowest rolling resistance tires we tested differed in efficiency by 60%, indicating that tire choice can have a bigger impact on fuel economy than most people realize. Rolling resistance differences of 20 to 30% are not uncommon among tires of an otherwise similar size, type, and level of performance. This means an individual vehicle could save up to 6% of its gasoline use if it were fitted with very efficient tires, paying for the modest additional cost of low rolling resistance tires in approximately a year of fuel savings. In other words, a typical compact car such as a Ford Focus can improve its mileage from 30 mpg to 32 mpg simply by using lower rolling resistance tires. For a car averaging 15,000 miles per year the fuel savings is about $50 (at $1.50 per gallon).
All tires have imprinted information on their sidewalls indicating size, type, load, and speed ratings, as described in Figure 2. The majority of tire models employ a “P” designation for passenger vehicle use, but some bear the “LT” designation for use with light trucks. In general, “P” tires appear to be gaining in popularity relative to “LT” tires of a given size.
In addition, the U.S. Department of Transportation requires each manufacturer to grade its tires under the Uniform Tire Quality Grading System (UTQGS) and establish ratings for the following characteristics: tread wear, traction, and temperature resistance. Unfortunately, the ultimate results published for each tire model are less “uniform” than they should be. The government specifies how each test should be conducted and prevents a manufacturer from claiming better performance than measured. However, it does not prevent manufacturers from claiming worse performance than measured. And, curiously enough, many do, primarily to amplify marketing distinctions among their tires at different price points and encourage buyers to move up from a “good” to a “better” or “best” model in a particular category.
Given the variability of ratings and the number of relevant factors, we have compiled our own composite metrics of performance for assessing tires, including the Federal ratings noted below and a variety of other published data.
5.Rolling On to the Future
Efforts to differentiate replacement tires on the basis of rolling resistance are still in their very early stages. Without data on the rolling resistance of all tire models across a range of sizes, it is impossible to say for sure if the models identified in this report represent the most efficient models or simply a subset of them. For now, consumers and fleet managers can start with the data shown here and request additional information directly from retailers and manufacturers.
附錄B:
低滾動阻力輪胎
根據(jù)報告80%的或更多的汽車的燃料是由摩擦和其他類似的損失所消耗的。翻新輪胎具有較低滾動阻力可節(jié)省1.5%至4.5%燃料。每年約2.37億美元的翻新輪胎在銷往美國。
1. 美國的燃料使用、影響和機遇儲蓄
美國的汽油使用對環(huán)境的影響是深遠的。擁有超過1.6億轎車和輕型卡車的道路上,每一年燃燒約126億加侖汽油。我們的燃料使用以約3%的速度繼續(xù)增長,在推動整體車輛數(shù)目持續(xù)增加和每輛汽車的平均距離上升帶動下,平均燃油經(jīng)濟性下降。
今天,輕型車(汽車和輕型卡車)的約20%的氮氧化物,27%的揮發(fā)性有機化合物,一氧化碳的51%,大約30%的二氧化碳(主溫室氣體)全部是由全國人類活動排放的。不斷上漲的燃料的使用也有保護荒野和(容易增加探索)公共土地,水資源(油輪和管道事故),國家安全產(chǎn)生巨大影響。因此,機會節(jié)省資金,提高燃料的使用,通過減少環(huán)境質量是明確的。
為橫跨整個車隊現(xiàn)有車輛節(jié)油最有希望的機會之一是利用而不是標準低滾動阻力輪胎置換模式。這一變化提高了車輛的固有效率,自動節(jié)省了典型的3萬至5萬英里的一套輪胎壽命燃料。
該報告審查了通過改進輪胎的節(jié)能技術的使用汽油的機會,特別是輪胎型號的建議而我們的初步測試數(shù)據(jù)表明,環(huán)境優(yōu)勢。其結果是適用于政府和企業(yè)車隊經(jīng)理以及個人輪胎買家。
2.輪胎如何能降低油耗
據(jù)美國國家科學院,約80%至88%在汽車的油箱的能源被浪費在各種熱,摩擦和備用的發(fā)動機和排氣系統(tǒng)損失。只留下約12%至20%轉換為實際車輛運動的勢能。減少車輛輪胎的滾動阻力是提高工作效率的主要途徑之一。這是不是一個輪胎的牽引或“握”在路面的措施,而是簡單地說明如何輕松地輪胎在道路上卷,盡量減少在輪胎側壁本身之間的輪胎與路面之間的輪胎和輪輞的熱量浪費的能源。
詳細的建模由國家可再生能源實驗室進行的結論是:根據(jù)駕駛條件和車輛類型,在輪胎滾動阻力減少10%應產(chǎn)生約1%至2%的燃油節(jié)省。據(jù)在美國加州能源委員會的研究,如果使用的所有更換輪胎具有低1.5%至4.滾動阻力,約5%汽油的使用總量可節(jié)省。這相當于大約為平均節(jié)省高達30汽油每車每年節(jié)約,或由$ 2.5至750億美元的全國平均汽油節(jié)約價值加侖。
由于他們的努力,以滿足聯(lián)邦燃油經(jīng)濟性標準的一部分,汽車制造商通常指定其新車低滾動阻力輪胎。 1980年至1994年,最低的滾動阻力輪胎型號實現(xiàn)了滾動阻力減少48%,并有可能以后繼續(xù)提高。這些原始設備(OE)的輪胎模型,偶爾會在替換輪胎市場,但往往只能通過特殊訂貨。一般來說,輪胎銷售給更換輪胎市場往往把對長壽和低價格更加重視,因此往往有較高的OE輪胎的滾動阻力比。
不幸的是兩個OE和更換輪胎的滾動阻力沒有任何標簽,目前,使車隊經(jīng)理和消費者愿意購買高能源效率的輪胎時,他們的第一套OE輪胎磨損已經(jīng)陷入困境。即使輪胎制造商聲稱,特別是更換車型比其他人更好的燃油經(jīng)濟性,他們并不總是一致的測試方法或使用獨立的實驗室數(shù)據(jù)支持這些說法。每年,約2.37億沒有提供滾動阻力的標簽的更換輪胎銷往美國的汽車和輕型卡車。
2002年,能源基金會資助的ecos咨詢,分析輪胎市場,選擇滾動阻力測試代表車型,并與綠色標記的工作建議,表現(xiàn)良好的同時實現(xiàn)低滾動阻力特別車型。這些發(fā)現(xiàn)第一次被發(fā)表在此選擇綠色的報告。的ecos咨詢的主要發(fā)現(xiàn)其他背景中可以找到為加州能源委員會編寫的另一份報告,在www.energy.ca.gov/reports/2003- 01 - 31_600 - 03 - 001CRVOL2.PDF可查。
3. 輪胎平衡性及其它注意事項
輪胎的生產(chǎn),像其他工業(yè)生產(chǎn)過程,涉及重大的開采和生產(chǎn),以及能源消耗和各種污染物的排放。這些制造每個階段以不同的方式影響環(huán)境。然而,輪胎,像其他消費產(chǎn)品的數(shù)量,實際上更多的環(huán)境影響在其使用和最終處置比他們負責制造。他們大大影響了車輛消耗的燃料量以它們所連接,導致全球變暖的排放以及當?shù)睾蛥^(qū)域空氣污染。他們創(chuàng)造微粒在穿著過程中的空氣污染,他們可以是一個重大的固體廢物問題,如果沒有妥善回收。
由意大利倍耐力輪胎制造商(圖1)所作的分析顯示,輪胎在整個生命周期能源消耗利用的主導地位。全生命周期的82%來自能源使用輪胎的貢獻,汽車燃料使用時,大約18%相比,與獲得的原料和生產(chǎn)的輪胎本身相關聯(lián)。因此,輪胎的滾動阻力很可能是在其生命周期比它的組成,壽命長,最終的命運或環(huán)境影響較大的因素,雖然這些因素也值得考慮。
這份報告的地方測得的輪胎滾動阻力的輪胎之后的預期壽命和性能特征的考慮密切合作,最大的意義。一個具有高可導致滾動阻力的輪胎對環(huán)境的影響深遠,即使它干練扎道路和八點零零零萬英里持續(xù)。與此相反,一個非常低滾動阻力輪胎可能不值得推薦,如果它的壽命是非常短或試驗數(shù)據(jù)表明,它提供了可憐的牽引力。
每一個輪胎目前市場上代表的期望之間的性能特點和價格各式各樣的平衡(我們調查的輪胎從25美元到200美元以上,每胎)。仔細地平衡這些特性不僅可以產(chǎn)生高效能的輪胎,而且是一個比目前市場上其他可用的環(huán)境更好。
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4. 輪胎滾動阻力評價和相關因素
滾動阻力歷來是通過測量汽車工程師學會(SAE)的測試程序為J1269稱為官方社會。它需要推出措施以每小時50英里的速度對一個固定的測功機輪胎的力。一個新的程序,SAE的J2452,承諾改善評估在不同的速度滾動阻力的準確性,但目前沒有獨立的實驗室有能力進行內部這類測試。因此,我們進行的所有測試均在一個單一的符合SAE J1269標準的獨立實驗室。
我們測試的最高和最低的滾動阻力在效率上相差60%,這表明輪胎的選擇有對燃油經(jīng)濟性有比大多數(shù)人意識到的更大的影響。 在類似的大小、類型和性能水平的輪胎中20%至30%的滾動阻力差距并不少見。這意味著如果配用合適的輪胎,為適度的低滾動阻力輪胎支付額外費,一輛私家車大約每年可節(jié)省燃料多達6%。換言之,一個典型的如福特福克斯小型汽車可以提高其從30英里到32英里的里程只需使用低滾動阻力輪胎。對于一個平均每年節(jié)省約15000英里的汽車的燃料約50美元(每加侖1.50美元)。
所有輪胎大小,類型,負載和速度等級都印在他們的側壁,如圖2所描述的信息。大多數(shù)型號的輪胎采用了“P”的客運車輛使用的名稱,但有些用“LT”的為輕型卡車使用的名稱。一般來說,“P”的輪胎似乎相對“LT”更受歡迎。
此外,美國運輸部要求各等級的輪胎制造商根據(jù)統(tǒng)一輪胎品質分級系(UTQGS),并為建立評級以下特點:胎面磨損,牽引和耐高溫性。不幸的是,每個輪胎型號公布的最終結果都比他們應該的要少。政府規(guī)定每個測試應該如何進行,并防止聲稱性能優(yōu)于衡量制造商。然而,它并不能阻止廠家聲稱比測量值差的性能。并且,奇怪的是,許多人,主要是為了擴大自己的輪胎營銷之間的區(qū)別在不同的價格點和鼓勵買家從一個“好” 移動到特定類別的“好”或“最佳”的模式。
由于收視率的變化及相關因素,我們已編制評估輪胎,包括聯(lián)邦額定值下文提到的和其他公布的我們自己的高性能復合指標各種數(shù)據(jù)。
5.滾動阻力的未來發(fā)展
努力在區(qū)分的基礎上更換輪胎滾動阻力仍處于非常初期的階段。如果沒有對整個的尺寸范圍內的所有型號的輪胎滾動阻力的數(shù)據(jù),就不可能肯定本報告確定的模式是否代表了最有效的模型或只是其中的一個子集?,F(xiàn)在,消費者和車隊經(jīng)理可以開始看在這里顯示的數(shù)據(jù),并直接要求零售商和制造商提供更多的信息。
10
SY-025-BY-5
畢業(yè)設計(論文)中期檢查表
填表日期
4月20日
迄今已進行 8 周剩余 8 周
學生姓名
吳 中
系部
汽車與交通工程學院
專業(yè)、班級
車輛工程07-1班
指導教師姓名
紀峻嶺
職稱
副教授
從事
專業(yè)
車輛工程
是否外聘
□是■否
題目名稱
彈性輪胎轉鼓試驗臺的設計
學
生
填
寫
畢業(yè)設計(論文)工作進度
已完成主要內容
待完成主要內容
1.確定試驗臺設計的總體方案
2.對試驗臺結構進行設計
3.對轉鼓結構和尺寸進行設計
4.確定液壓加載機構的系統(tǒng)原理結構
5.對液壓缸進行結構尺寸的設計
6.選擇控制閥,液壓泵等液壓裝置裝置
1進行電機和相關傳感器進行的選擇
2.對傳動機構進行設計
3.運動關系分析與運算
5.畫裝配圖和零件圖
6.書寫設計說明書
存在問題及努力方向
存在問題:在設計的過程中,對液壓缸的設計過程還是不太熟,結構形式可能還仍有待完善。對電機的認識還比較少。
努力方向:經(jīng)過一部分的計算,使我對液壓系統(tǒng)的設計有了一定的了解,我會在今后的努力中使其更加合理;同時,加緊對電機的研究選出合適的電機。
學生簽字:
指導教師
意 見
指導教師簽字: 年 月 日
教研室
意 見
教研室主任簽字: 年 月 日
SY-025-BY-2
畢業(yè)設計(論文)任務書
學生姓名
吳 中
系部
汽車與交通工程學院
專業(yè)、班級
車輛工程B07-1
指導教師姓名
紀峻嶺
職稱
副教授
從事
專業(yè)
車輛工程
是否外聘
□是■否
題目名稱
彈性輪胎轉鼓試驗臺的設計
一、設計(論文)目的、意義
設計目的:為模擬車輛實際行駛狀態(tài),準確測定車輛滾動阻力系數(shù),為確定滾動阻力系數(shù)的大小、分析滾動阻力系數(shù)的影響因素提供參考。
設計意義:汽車行駛阻力直接影響汽車的動力性、經(jīng)濟性和操縱穩(wěn)定性等幾大使用性能,而滾動阻力是汽車行駛阻力中的常有阻力的一種,其大小主要取決于滾動阻力系數(shù),而滾動阻力的大小與輪胎和道路有較大的關系,因此對與道路有密切關系的滾動阻力系數(shù)的測定具有十分重要的意義。
二、設計(論文)內容、技術要求(研究方法)
1、主要設計內容
根據(jù)車輪的實際工作狀態(tài),開發(fā)可以模擬汽車實際使用狀態(tài)的摩擦系數(shù)測定系統(tǒng),要求設計的系統(tǒng)采用測功機輸入動力,制動系消耗功率,并能準確測量輸入和輸出的轉矩參數(shù),進而通過運算得到滾動阻力系數(shù)的準確值。具體設計內容包括:滾動阻力系數(shù)測試系統(tǒng)的總體方案,驅動電機和制動電機的選擇,加載機構和傳動機構的設計,運動關系的分析及試驗結果的運算和處理。
2、主要技術指標、要求
1)確定汽車驅動車輪的輸入功率;
2)確定汽車驅動車輪的輸出功率;
3)驅動車輪的加載情況;
4)測試結果及數(shù)據(jù)分析的準確性。
三、設計(論文)完成后應提交的成果
1、設計說明書一份,1.5萬字以上;
2、試驗臺圖紙一套。
3、設計的電子稿件一份。
四、設計(論文)進度安排
1、進行文獻檢索查,查看相關資料。 第1-2周(2月28~3月13日)
2、初步確定設計的總體方案,對系統(tǒng)進行初步設計。 第3-6周(3月14~4月10日)
3、提交設計草稿,進行討論,修定。 第 7 周(4月11~4月17日)
4、對電機進行選取,對傳動系統(tǒng)進行設計,繪制圖紙。 第8-12周(4月18~5月22日)
5、提交設計,教師審核。 第13-14周(5月23~6月5日)
6、設計修改。 第 15 周(6月6~6月12日)
7、裝訂設計,準備答辯。 第 16 周(6月13~6月19日)
8、設計答辯。 第 17 周(6月20~6月24日)
五、主要參考資料
[1]張利平.測功機原理.北京:化學工業(yè)出版社,2005
[2]黃緯綱,王旭永,王顯正等.摩擦系數(shù)產(chǎn)生的機理研究.上海交通大學學報,1998,(12)
[3]付百學.汽車試驗學.北京;機械工業(yè)出版社,2008
[4]馮晉祥.機械設計.北京:人民交通出版社,
[5]汽車工程手冊編委會.汽車工程手冊.北京:人民交通出版社,2001
[6]黃聲顯.汽車試驗與檢測技術。北京:人民交通出版社,2005
[7]謝金元.輪胎摩擦理論的研究.,北京;機械工業(yè)出版社,2006(4)
六、備注
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