Title: Green tire
English: green tires
Explanation:
From the perspective of energy saving and emission reduction, tires are also a source of pollution.
Due to rolling resistance, the fuel consumption caused by tires accounts for about 20% of the total fuel consumption of cars, but in trucks, this proportion has increased to 1/3.
According to the data of the International Energy Agency, there are currently 830 million vehicles in the world, and their carbon dioxide emissions account for 18% of the total global carbon dioxide emissions. The World Business Council for Sustainable Development predicts that the carbon dioxide emitted by automobiles will double by 2030.
Such a high growth rate of carbon emissions obviously runs counter to the international trend of energy conservation and emission reduction. As a result, Europe has put forward new requirements for automobile emission reduction.
In the "Energy and Climate Plan from June 5438 to October 2007 10", Council of Europe reiterated its determination to "improve energy efficiency and reduce carbon dioxide emissions from automobiles". Council of Europe emphasized that "in order to achieve the goal of 120g of carbon dioxide emissions per kilometer by 20 12 years through comprehensive and consistent measures, further measures will be formulated to control the carbon dioxide emissions of automobiles". In mid-2008, the Council of Europe will submit the framework of legal bills to the Council and the European Parliament, so as to finally achieve this goal.
This is not an easy job.
The carbon emission target of 65,438+0.20 grams per kilometer means that in the next four years, automobile manufacturers must improve all their vehicles to achieve the average level of reducing carbon dioxide emissions by 20 grams per kilometer.
Michelin's green tire products have been on the market since 1992. The principle is that silicon is mixed into the tire tread as a partial substitute for carbon black, and silicon is helpful to reduce the rolling resistance without reducing the tire grip (especially the wet road surface) and wear resistance.
Undeniably, this innovative technology greatly reduces the energy consumption required for vehicle running, and the fuel consumption per 100 kilometers can be reduced by 0. 15 liter.
According to Michelin's statistics, every second, Michelin green tires rolling in every corner of the world can save fuel consumption by 43.9 1 liter/second and help reduce carbon dioxide emissions by more than 109.6438+04 kg.
Since 2006, Michelin has initiated the introduction of an index system similar to the automobile industry, that is, the energy-saving index, to classify tire fuel consumption and carbon dioxide emissions. The index is divided into Grade A (the tire with the best energy-saving performance) and Grade I (which has not been specifically defined) with the lowest efficiency. Tires below the lowest grade will not be sold in Europe.
This indicator system is planned to be implemented in Europe from 20 1 1. By then, car owners who are interested in buying tires can see the energy-saving indicators of the tires they are considering at a glance.
However, the implementation of this energy-saving index may be a precursor to reshuffle for the whole tire industry.
1 Advantages of green tires
Green tires have the advantages of good elasticity, low rolling resistance, low fuel consumption, low calorific value, wear resistance, puncture resistance, large bearing capacity and comfortable riding. Compared with traditional tires, it highlights the advantages of environmental protection, energy saving, new technology and new materials.
1. 1 high environmental protection
Due to the addition of carcinogenic rubber compounding ingredients, traditional tires are discharged into the air with tread wear, which seriously pollutes the environment. At the same time, hundreds of millions of tires are abandoned every year in the world. They not only occupy a lot of space, but also are difficult to decompose and pose a great threat to the environment, so they are called "black pollution". With the continuous improvement of people's awareness of environmental protection, while continuing to strive to reduce rolling resistance, people began to pay attention to the use of materials that do not pollute the environment to make tires, and strive to extend the driving mileage of tires to reduce the number of waste tires. After a large number of cars use green tires, it plays a great role in saving fuel and reducing pollution. The wide application of green tires will save millions of barrels of oil every year around the world and significantly reduce carbon monoxide emissions.
1.2 Low consumption
The black tires used are made of standard synthetic rubber and natural rubber. Under the condition of increasing the driving temperature of the car, the structure and performance of the protective material have changed, and the rolling resistance of the wheel has also increased. Compared with ordinary tires, green tires reduce the weight of tires and the energy consumption (hysteresis loss) of composites. Therefore, compared with the tires of the same specification, the rolling resistance of green tires can be reduced by 22%-35%, so that the fuel consumption of automobiles can be reduced by 3%-8%, thus reducing the CO emission of automobiles, and other properties such as wear resistance, low noise and wet and dry grip can also be maintained at a good level.
1.3 Super safe
By optimizing the carcass design, the green tire improves the grip performance of the car on the smooth road with excellent elastic tread, which makes the driving more stable, the braking distance shorter, and greatly improves the driving safety. The research shows that the friction generated by green tires can reduce the braking distance of automobiles on slippery or icy roads by 65,438+05% and improve the driving performance of automobiles in winter by 65,438+00%-65,438+05%. This is of great significance to reduce the accident rate and casualties.
Two methods of designing green tires
Theoretically, the ways to reduce automobile fuel consumption are light weight, reducing tire rolling resistance and using lean mixture engine. In fact, only reducing tire rolling resistance is the most feasible way to design green tires. The results show that tire mold, pattern design, tire structure and material all have effects on tire rolling resistance. The fuel consumed to overcome the tire rolling resistance accounts for 14.4% of the total fuel consumption, while the rolling resistance generated by the tread alone accounts for 49% of the tire rolling resistance. The influence proportions of other components are: sidewall 14%, carcass 1 1%, bead 1 1%, and belt. The oil consumption directly caused by tread accounts for about 7. 1%. Reducing the rolling resistance of the tread and ensuring good wet skid resistance will be the most basic requirements of green tires.
Green tire technology mainly starts with selecting suitable rubber varieties and compounding agents, improving the tread compound formula, supplemented by structural design means such as thinning the carcass and optimizing the tire contour, so as to reduce the tire rolling resistance. It can be predicted that the involvement of computer-aided design technology and the introduction of polymer molecular orientation design results will undoubtedly accelerate the development process of green tires.
2. 1 structural design of green tire
2. 1. 1 radial of carcass structure
Tire structure can be roughly divided into two types, namely radial structure and oblique structure. The fundamental difference between meridian structure and skew structure lies in the carcass. The carcass is the foundation of the tire, and the tire is a layered structure composed of cords. The upper part of the carcass layer has a belt layer with cords arranged in the circumferential direction. This structure can make full use of cord strength, so the number of cord layers in radial tire is 40%-50% less than that in bias tire.
From the design point of view, bias tires have many limitations. Because of the high friction of cross cords of bias tire, the carcass is easy to heat up and accelerate the wear of tread pattern, and its cord arrangement can not provide excellent handling performance and ride comfort. The steel wire belt of radial tire has good flexibility and durability to adapt to the irregular impact of road surface. Its ply structure also means less friction during driving, thus obtaining longer tread life and better fuel economy.
The advantages of radial tire itself make tubeless tire possible. Tubeless tires have recognized advantages. When a tire is punctured, it will not burst like a tire with an inner tube (ordinary bias tire with an inner tube), but will maintain the air pressure for a period of time, thus improving safety.
Due to the special structure of radial tire carcass, the tire has great grip and good driving effect. Compared with cars equipped with bias tires, cars equipped with radial tires can improve wear resistance by 50%- 100%, reduce rolling resistance by 20%-30%, and save fuel consumption by about 6%-8%. Because of this, the same model uses radial tires, which have better handling and better driving comfort than bias tires.
To sum up, radial carcass structure is the first choice for green tire structure design.
When the tire section width increases, the rolling resistance decreases. This is because the increase of tire section width reduces sidewall stiffness, while sidewall deformation, which has little influence on rolling resistance, increases, while tread deformation, which has great influence on rolling resistance, decreases. In addition, with the widening of tire section width, the energy loss of main components such as tread and belt decreases. Therefore, increasing the tire section width is beneficial to reduce the rolling resistance.
If the height of the filler strip increases, the rolling resistance will also increase. Because with the increase of the height of the filled rubber strip, the volume of material causing hysteresis loss increases, and the energy loss at the lower part of the side wall also increases. In addition, the increase of filler height will reduce the deformation of sidewall due to the increase of sidewall stiffness, while the deformation of tread which has a great influence on rolling resistance will increase relatively, resulting in the increase of rolling resistance. At present, the design of carcass structure is developing towards low profile.
2. 1.2 tread
When the tread radius increases, the rolling resistance of the tire can be reduced. This is because when the tread radius increases, the tire will buckle on the plane ground, thus reducing the strain energy generated by the buckling deformation in the tire section direction. That is to say, the rolling resistance decreases with the increase of tread radius, which is mainly due to the decrease of energy loss of crown and belt. In the future, the tread structure of green tires should develop in the following directions:
(1) Double tread
Double tread tire has the advantages of high speed, stability, wear resistance and low heat generation. Generally, it consists of tread and tread base. The tread and tread base rubber have different dynamic modulus and tanδ. Relevant literature indicates that the dynamic modulus of tread is greater than that of tread base (≥8.5 MPa), tanδ is greater than 0. 12, and the ratio of tread base thickness to tread thickness is 0.25-0.70.
(2) Foamed tread
The foamed tread is made of foamed rubber. In addition to the general components of tread compound, it also contains syndiotactic 1, 2- polybutadiene (powder with average particle size of 60 nm), foaming agent, antioxidant and other additives. The test shows that the tire made of foamed tread has good braking and traction performance on wet and dry roads, especially on ice, and can completely maintain driving stability, durability and low fuel consumption even in hot summer, which is the development direction of green tire tread compound.
When designing the tire structure, it must be able to reduce the rolling resistance without reducing other characteristics (wet skid, safety, vibration, etc.). ) contradicts the rolling resistance. As a concrete scheme to reduce rolling resistance, tire shape and rubber configuration must be considered comprehensively, especially the influence of belt and carcass ply composed of composite materials on rolling resistance. As a tire structure research, we should not only rely on past intuition and experience, but also use simulation technology to accelerate the development of low rolling resistance tires.
The finite element method has used the energy structure equation of rubber material for decades, and transformed it from linear elastic equation to Mooney-Rivlin equation, and recently introduced the nonlinear structure equation in the field of large deformation. Filler rubber, which is used as many industrial rubber materials such as tires, has nonlinear strain due to its viscoelastic properties such as storage modulus, loss modulus and tan8 in 0- 100% strain field, which is generally understood as Payne effect. In recent years, some people have proposed a nonlinear structural equation considering this point. When the wheel rotates normally, the strain also accounts for most of the tire deformation, so it is particularly important to control the viscoelasticity in this strain field to control the tire rolling resistance. In fact, by applying the nonlinear viscoelastic structural equation representing the viscoelastic characteristics of filled rubber in the strain range of 0- 100% to the finite element analysis, the prediction accuracy of tire rolling resistance tanδ is greatly improved compared with the traditional prediction. In this way, the accuracy and efficiency of tire structure design, new material development and formula design for reducing tire rolling resistance are improved accordingly. At present, a green tire design method has been formed by simulating tire rolling resistance by finite element method.
Bridgestone has successfully developed a tire design technology that can greatly reduce rolling resistance and improve wear resistance, which is called Bridgestone ecological tire design technology.
The purpose of Bridgestone's development and design technology is to focus on the eccentric deformation of tires in the process of developing tire fuel-saving technology. By developing a new tire shape and increasing this eccentric deformation, the tire rolling resistance which has a great influence on vehicle fuel can be greatly reduced, and the wear resistance can be further improved.
If the tire rotates under load, resistance will be generated due to the deformation of the tire contact surface and the tire itself, and then energy loss with heat energy as the king will occur. A tire will lose rolling resistance, which is called a tire. By reducing the rolling resistance of tires, the fuel consumption of vehicles can be reduced.
In the past, developing tread rubber with less energy loss can effectively reduce rolling resistance, mainly through developing rubber materials. However, the use of rubber with less energy loss will reduce the wear resistance, which makes it difficult to drive a tire with low rolling resistance.
The new technology developed by Bridgestone can restrain the decrease of rolling resistance caused by refueling (in order to reduce rolling resistance) by adopting a new tire shape that can greatly reduce tire energy loss.
Bridgestone believes that tires developed with this technology can get twice the result with half the effort if they are matched with environmentally friendly vehicles, such as electric vehicles (EV).
Bridgestone has demonstrated the tire prototype developed by this technology at the 27th Tokyo Auto Show on October 24th, 2003/KLOC-0.
The loading test shows that (the tire size of the loading test is 235/35R 19, the number of passengers is 4, and the tire inflation pressure is 230 kPa), the wear resistance of the sample tire is 50% higher than that of the ordinary tire of the same specification.
2.2 Green tire materials
Generally speaking, there are two basic methods to reduce tire rolling resistance:
(1) Reduce tire quality
Reducing tire mass is the fastest and most effective way to reduce tire rolling resistance. In order to ensure the quality of small tires, the minimum component thickness must be adopted on the premise of ensuring tire performance. Tire manufacturers must strictly control the process to ensure the minimum thickness of parts, and never allow factories to increase the thickness of parts without authorization in order to solve production problems. Using lightweight materials is also an effective way to reduce the weight of tires. Using aramid tape instead of steel tape is an obvious example.
(2) Reducing energy consumption (hysteresis loss) of materials The second way to reduce tire rolling resistance is to reduce energy loss (hysteresis loss) of tire materials. The hysteresis loss of polyester cord is large, but after proper improvement, a variety with less hysteresis loss can be introduced.
2.2. 1 polymer system
2.2. 1. 1 natural rubber
Natural rubber is nonpolar rubber. Although it has excellent electrical properties, it is easy to swell in nonpolar solvents, so its oil resistance and organic solvent resistance are poor. NR molecule contains unsaturated double bonds, so its thermal oxidative aging resistance, ozone oxidation resistance and ultraviolet resistance are poor, which limits its application in some special occasions. And NR can greatly expand the application range of NR through modification.
(1) epoxidized natural rubber
Epoxidized natural rubber (ENR) is a special natural rubber chemically modified from natural rubber (NR). Compared with NR, ENR has completely different viscoelastic and thermodynamic properties, such as excellent air tightness, adhesion, wet skid resistance and good oil resistance. ENR can be firmly combined with polar fillers (such as silica), and ENR vulcanizate can still maintain the high modulus and tensile strength of NR without fillers. ENR 50 has good oil resistance and good adhesion. When it is used in tire tread compound, the strong interaction between ENR and silica is an important factor to improve the comprehensive performance of rolling resistance and wet grip without coupling agent. When ENR25 is mixed with silica/carbon black filler, the best wear resistance can be obtained.
(2) Grafting natural rubber
At present, methyl methacrylate (MMA) grafted NR is the most studied. MMA grafted NR has high elongation, high hardness, good impact resistance, bending crack resistance, dynamic fatigue performance, adhesion and good filling property. It is mainly used in manufacturing elastic products with good impact performance, such as the inner lining of tubeless tires. If it is used together with styrene-butadiene rubber, it can be used as bead triangle rubber compound, and its green rubber strength and adhesion to traveler are obviously improved, and the stiffness of traveler is increased, and the shape of traveler remains stable. 2.2. 1.2 polyisoprene rubber
The new development of isoprene is the synthesis of 3,4-polyisoprene rubber (high glass transition temperature). This kind of rubber can be used with natural rubber, styrene-butadiene rubber and polybutadiene rubber to improve the grip performance. Polymers of isoprene and butadiene have been successfully developed, and trimers of isoprene with styrene and butadiene have also been successfully studied. The tread rubber made of these rubbers has a good comprehensive balance between rolling resistance and wet road grip.
China patent ZL95 1 10352.0 introduces a new technology of directly synthesizing trans-1, 4- polyisoprene (TPI) powder by bulk precipitation polymerization of isoprene catalyzed by supported titanium. It is reported that 20-25 parts by weight of TPI is used to replace cars and light semi-steel radial tires made of styrene-butadiene rubber, which has achieved good comprehensive driving performance and reduced fuel consumption by about 2.5% in the fuel consumption test of 100 kilometers.
In fact, you will know under Baidu.