Safety tire, which is "Run-Flat tire" in English, means that after the tire is punctured by foreign objects, it will not leak or leak very slowly for a period of time, and it can keep running for a period of time. The tire industry literally translates as "run-flat tire", also known as "run-flat tire". Since 1934, Goodyear obtained the first patent for safe tires, the tire industry has gone through more than 70 years of research and development of safe tires.
1. Early stage of safety tire development: technical exploration, let a hundred flowers blossom.
"Stab resistance, explosion resistance and walking after pressure loss" are the three basic requirements for safe tires. For "can walk after losing pressure", its measurement indexes include driving speed and driving distance after losing pressure. As far as safe tires are concerned, the current standard in the automobile industry is to drive at a speed of 50-55 mph (80-88 km/h) 100 mile (160 km). In order to achieve this goal, people have tried many methods in the past 70 years, especially in the first 60 years. These methods are various and have their own advantages and disadvantages. Representative safety tire technologies in the early stage of development are:
(1) Increasing the tread thickness to prevent foreign bodies from penetrating the tread has a simple structure but poor lateral stability.
(2) The structure of embedding small metal pieces in tread rubber to stop foreign bodies is simple, but the lateral stability and shock absorption are poor.
(3) The small capsules filled with viscous liquid are placed in the inner cavity of the tire in advance or stuck on the inner wall of the tire, or an adhesive layer is preset in the carcass, and sometimes a small amount of synthetic microporous fiber flocs with low specific gravity are placed in the inner cavity of the tire. When the tire is punctured, viscous liquid escapes to the perforation and blocks the hole together with the synthetic microporous fiber floc; A safety tire with this structure is usually called a self-sealing tire. Viscous liquid can reduce the heat generated by friction on the inner wall of flat tire, but viscous liquid or viscose is easy to fail; Because the small capsules and fiber flocs move freely in the tire cavity, the balance performance of the tire is affected.
(4) A large tire covers a small tire, that is, a smaller tread-free tire (inner tube) with a common inner tube is placed in the inner cavity of the tubeless tire (outer tire), and an inflation space (outer air chamber) is left between the inner tube and the outer tire, and when the outer tire loses pressure, the inner tube works; The inner and outer air chambers are respectively provided with a set of independent valve cores and nozzles; The safety tire with this structure is usually called multi-cavity tire, which has complex structure, obvious increase in tire weight and high manufacturing cost.
(5) Install a reinforced inner tube with a cord reinforcement at the radial top of the tire cavity. This kind of structure is usually called explosion-proof inner tube tire, which is simple in structure and does not affect the ride comfort.
(6) The inner cavity of the tire is filled with sponge and not inflated. A safety tire with this structure is usually called a sponge-filled tire. The carcass is hard, the ride comfort is poor, and the tire heats up greatly during driving, which is not suitable for high-speed vehicles.
(7) The inner sides of the side walls are made into air bags, and sponges are filled in the air bags, or reinforcing films with crescent cross sections are pasted on the inner surfaces of the two side walls. The safety tire with this structure is usually called sidewall reinforced tire, which has high sidewall rigidity, good lateral stability and low internal heat after pressure loss.
(8) Install a detachable elastic support ring in the inner cavity of the tire to support the tread and reinforce the sidewall after the tire loses pressure. The safety tire with this structure is usually called a tire with internal support. The inner wall of the tire is in contact with the elastic support ring and generates heat due to friction, which is easy to cause early damage.
(9) Glue the bead to the rim seat with epoxy resin, so that the tire will not fall off after losing pressure. This is the prototype of the special rim in the later period, and the rims of the tires are connected into a whole, which increases the difficulty of reusing the rims.
After long-term exploration and repeated experiments, by the middle and late 1990s, some of the above methods have been eliminated, such as simply embedding small metal pieces, explosion-proof inner tubes and multi-cavities. Although some methods are still in use, their products have no market or the original market has obviously shrunk, such as liquid self-sealing, and some methods have been improved and gradually become mainstream technologies, such as sidewall reinforcement, internal support and special rims. During this period, there is a new trend, which is to combine, integrate and optimize various methods that were originally used alone, and evolve into new technologies that can manufacture safety tires with better comprehensive performance and more competitiveness, such as sidewall reinforcement+inner support, special rim+sidewall reinforcement, special rim+inner support, etc. It can be said that in the 60 years from the 1930s to the mid-1990s, safety tires changed from technical exploration and blooming to relatively centralized and basically stereotyped, completing the historical process of technical method screening and process route determination, and entering the middle stage from the initial stage of development.
2. Mid-term development of safety tires: technical optimization, gradually becoming a genre.
Since the mid-to-late 1990s, the focus of safety tires has shifted to making technology more pure, technology more mature and products more effective. On the basis of initial development, through integration and optimization, the current safety tire technology has formed two categories divided by tire structure and two categories divided by matching rim.
According to the tire structure, there are two kinds of safety tire technologies: (1) Self-sealing safety tires are filled with enough sealant in the tire cavity or sealing layer in advance. After the tire is punctured by a foreign body, the sealant automatically flows to the perforation to block the hole, so as to prevent the tire internal pressure from falling, thus maintaining the normal driving state; (2) Rigid support safety tires can be subdivided into self-supporting type and additional supporting type. Compared with ordinary tires, the former does not add any parts, but only through the special design or enhancement of an original part, so that the tire can still maintain the driving contour after losing pressure, a typical example is the sidewall reinforcement type; The latter achieves the purpose of maintaining the driving contour after tire pressure loss by introducing parts that ordinary tires do not have. A typical example is the internal support type.
According to the matching rims, there are two kinds of safety tire technologies: (1) ordinary (standard) rim type; (2) Special (non-standard) rim type. According to the purpose, there are two types: (1) safety tires to ensure the temporary smooth running of the car; (2) Safety tires that run continuously for a long time.
In fact, the above two classification conditions can also be understood as the technical means of manufacturing safety tires, namely ((1) self-sealing technology; (2) Rigid support technology; (3) Special (non-standard) rim technology. As mentioned above, most safety tires can be classified into a single category in the early stage of development, that is to say, due to the limitation of conditions, it is more inclined to use a single technical means to manufacture safety tires. The more developed countries are, the more difficult it is to classify them into a certain category, because the existing safety tires are already a combination of various technologies.
The new safety tire products commercialized in recent years 10 mainly include:
Gen* Seal of Continental A.G and Tiger Claw NailGard of French Michelin are all products that were all the rage in the 1990s. Continental A.G' s Gen* Seal is a self-sealing tubeless safety tire, which was successfully developed by Continental in the late 1980s. Seen from the tire cross-section, the part between the two shoulders in the Gen* sealing cavity is provided with a special stab-resistant layer, which is filled with a flowable soft sealant. When the Gen* Seal is punctured or the punctured substance is pulled out, the soft sealant will automatically flow to the puncture under the internal pressure of tire inflation, blocking the hole, and even if the hole injury is as deep as 3/ 16 inches, the tire will not leak. Mainland China suggested that Gen* Seal should be used in conjunction with tire inflation internal pressure monitoring system (TPMS), which will give an alarm signal according to the decrease of tire rolling radius.
TigerPaw NailGard of French Michelin Group, like Gen* Seal, is a self-sealing tubeless safety tire, which was successfully developed by French Michelin Group at 1998. Its structure and technical indicators are basically the same as mainland Gen* Seal. From the brand name of this tire as Uniroyal, it is not difficult to judge that it belongs to the mid-range product in Michelin tire product series.
(2) Special rims+self-supporting safety tires
As the name implies, this kind of safety tire must be installed on a non-standard rim, and a part of the tire should be thickened or lined with a special reinforcing layer. The most common safety tire belonging to this category is the special rim+sidewall reinforced safety tire. The special rim can effectively prevent the tire from falling off after the tire loses pressure. Representative products are Expedia tire-rim assembly of Bridgestone Company in Japan and MXV4 tire of Michelin Group Company in France.
Japan Bridgestone Company successfully developed Expedia tire rim assembly in March 1992, and sold it in the European market early next year. The assembly consists of three parts: (1) safety tire-the sidewall is lined with special ribs, which can support the weight of the car when the tire loses pressure; At the same time, the heat resistance of the rubber compound is very good, and it remains elastic after the tire loses pressure, so as to ensure that the tire will not lose its basic running function, and there is no need to worry about tire damage caused by internal friction; (2) Wedge rim-This is a special kind of rim, similar to the CTS reverse rim in mainland Germany. On the basis of ordinary rims, a hump flange is added to each of the two bead seats. After the tire leaks, the hump flange plays a role in preventing the tire from falling off; (3)TPMS consists of a pressure sensor fixed on the rim seat and a buzzer or indicator light installed in the car; When the tire inflation pressure drops to the set value, the buzzer sounds or the indicator light flashes. Expedia assembly can drive out of 150 miles (240 kilometers) at a speed of 55 miles per hour (88 kilometers per hour) without internal pressure.
Michelin Group of France successfully developed MXV4 tires in 1994, and sold them in the North American replacement parts market in 1997. MXV4 tires are characterized by good handling performance after losing pressure. TPMS consists of a sensor embedded in the rim seat and a programmable digital display installed on the dashboard of the cab. 1998 MXV4 has developed into a series of products with various specifications and models, among which MXV4ZP can travel 50 miles (80km) at a speed of 55mph (88km/h) with zero internal pressure. At that time, the price of MXV4 ZP was 40-50 dollars higher than that of ordinary tires, and the price of TPMS for matching was 300-400 dollars.
(3) Special rim+additional support type safety tire
This kind of safety tire not only needs to be used with special rims, but also has a feature that there are some parts inside the tire that ordinary tires don't have, such as inner supports. The most representative products are PAX of Michelin Group in France, CWS system of Continental Company in Germany and EMI (Integral Foamed Tire) of Pirelli SpA in Italy.
1At the beginning of 997, Michelin Group of France solemnly announced to the media that it had successfully developed a unique safety tire-PAV (Vertical Fixed Pneumatic Tire). /kloc-in the summer of 0/998, PAV was supplied to European automobile manufacturers as original parts. 1999 Michelin upgraded PAV technology and changed its name to PAX.
As a safety tire with the lowest cross-section in the world (Series 60), PAX was able to drive 65,438+025 miles (200 kilometers) at a speed of 50 miles/hour (80 kilometers/hour) after losing pressure. Its structural features are as follows: (1) The widest tire section is at the bead, and the diameter of the bead is greater than or equal to the diameter of the tire outer edge; (2) The tire sidewall is nearly vertical, instead of bulging like ordinary tires, and the sidewall height is only1/2 of ordinary tires of the same specification; (3) Specially-made flat-bottom rim with built-in rubber ring plays the role of locking the bead and supporting the tread.
Michelin requires that PAX must be used with TPMS, because PAX's performance is so good. Without TPMS, drivers can't distinguish between inflated driving state and depressurized driving state by feeling, and as a result, they find that they have been driving without pressure for a long time when they arrive at their destination. Driving under pressure and load causes great burden to tires, so both ordinary tires and safe tires are in an abnormal state. The purpose of TPMS is to shorten the time that Parks is in an abnormal state as much as possible and prolong the life of Parks. This is also the reason why almost all safety tire manufacturers suggest or require TPMS.
The CWS system of Continental Company was successfully developed at the end of 1999. Its basic structure is similar to Michelin PAX, which consists of four parts: (1) flexible bead without bead ring reinforcement; (2) steel wire reinforced rubber support ring (CSR(3) special rim; (4) The air leakage detection device (DDS )o of TPMS or CWS system has been installed in 200 1 car.
Italian Pirelli company EM worker 1994 introduced. Its basic structure is that butyl rubber foam ring made by special technology is preset in the tire cavity. When the tire is not deflated, the internal pressure will press the foam ring against the rim, which can reduce the stress concentration and adjust the inertia of the rim. Once the tire loses pressure, the foam ring immediately expands rapidly, filling the whole tire cavity and supporting the carcass to achieve the tire inflation effect and maintain the normal running state of the tire. EMI has matched the car.
(4) Self-supporting+additive supporting safety tire
This kind of safety tire can be used when it is installed on a common rim, but there are some extra supporting parts, such as the inner supporting ring, besides some parts thickened inside the tire. Self-supporting+additive support technology is especially suitable for high-profile tires and heavy vehicles, which ensures the support of tires after pressure loss and prevents the inner surfaces of tires from rubbing against each other and causing early damage. The most representative product is Engle EMTo of Goodyear Tire & Rubber Company.
Engle EMT of Goodyear Tire & Rubber Company in the United States was produced after further improving TPMS and improving tire structure (i.e. strengthening sidewall) on the basis of double Engle. The most attractive feature of Engle EMT is that it is installed on ordinary rims, which indicates that Goodyear has reached the leading level in the field of safety tire technology. Compared with other safety tires with special rims, EMT is undoubtedly more competitive in the market. Engle EMT tire can keep its original inflated shape under pressure loss, and the inner wall of tire cavity will not be worn and close to each other, thus maintaining the basic driving performance.
By the end of 1997, Engle EMT had eight specifications and models suitable for cars, off-road vehicles and multi-purpose sports cars, and the price was higher than that of ordinary tires 10%} 15. Goodyear suggested that English should be used with TPMS. Of course, if TPMS is not equipped, it will not affect the performance of Engle EMT. TPMS costs $ 250-300 per set. The performance index of Engle EMT is to drive 200 miles (320 kilometers) at a speed of 55 miles/hour (88 kilometers/hour) after losing pressure.
Engle EMT's parallel substitute product, Engleemt series, was established in 199 1, with four sub-series from 1994: A to D * *. Where GS-A is an asymmetric tread tire and GS-D is a directional tread tire. GS-C has two layers of steel wire belts wound by special methods, which are not only resistant to high temperature, but also have low calorific value, ensuring the original handling performance of 100% when driving without pressure.
(5) Self-supporting safety tires
This is also a kind of safety tire, which can be used on ordinary rims. By specially designing or strengthening a certain part of the tire carcass, the purpose of maintaining the running contour of the tire after pressure loss and having enough rigidity to bear the load of the vehicle and passengers can be achieved. It should be said that this is a kind of safety tire with the simplest structure and the simplest use. However, the self-supporting technology has two disadvantages: (1) the sidewall stiffness is too large, which affects the ride comfort; (2) It is more suitable for low-profile tires and lighter vehicles. The most representative products are Hawk series safety tires of Bridgestone Company in Japan, CCT of Sumitomo Rubber Industry Co., Ltd. in Japan and Pirelli EUFORI &; reg。
Hawk series safety tires produced by Bridgestone Company in Japan were listed in 1999. They have four characteristics: (1) suitable for ordinary rims; (2) No internal support; (3) It belongs to an ordinary road section; ; 4) The weight is lighter than that of similar Goodyear products. The above characteristics are obtained by thickening the tire sidewall and adopting a unique belt design. Among them, Eagle brand tires are different from other safety tires without special rims and internal supports, so they are more popular in the market than similar products. Hawk tires can travel 50 miles (80 kilometers) at a speed of 55 miles/hour (88 kilometers/hour) without pressure loss.
Sumitomo Rubber Industry Corporation of Japan introduced CCT (Comprehensive Technical Tire) in June 2000. Although it is rigid and self-supporting, it is different from the traditional technology. At present, self-supporting technologies, such as Bridgestone Hawk, Michelin MXV4, etc., all use more rubber and fabric to thicken and strengthen the sidewall and improve the rigidity of the parts, so as to achieve the purpose of maintaining the inflated contour of the tire after losing pressure. Doing so will inevitably increase the weight of the tire (usually 20%-4 0% heavier than ordinary tires) and worsen the ride comfort. The CCT contour line from the tread to the sidewall has several continuously changing curvatures. Even if the sidewall is thinner, the tire with this contour still has good self-supporting ability, so it is also called lightweight safety tire.
Italian Pirelli Company launches EUFORI &；; Reg This is the first radial safety tire produced with MIRS (Modular Integrated Automation System) technology. It has intelligent self-supporting side walls, and can drive safely for 90 miles (150 km) at a speed of 50 mph (80 km/h) without pressure. Because it is publicly named online, it is also called e-fetus. Pirelli also recommends that you use Eufori &；; Reg better match TPMS.
M-worker RS is an innovative technology developed by Pirelli in the early 1990s. At present, the company has established several factories in Italy, the United States, Britain and Germany, using MIRS technology to produce tires. Products include passenger car tires, light truck tires and truck tires, but it is the first time to produce safety tires by using MIRS technology.
(6) Articulated tires
1993, Airboss Company of Malaysia Asia successfully developed an articulated industrial tire/rim system-AirBos: articulated joint, which consists of articulated tires and special rims, and is suitable for loaders and excavators. When the articulated tire is not equipped with a rim, it looks like a rubber crawler, consisting of 10 hollow rubber parts reinforced with thin steel plates, and its cross section is trapezoidal. There is a hole in the bottom of each rubber part, and bolts have been installed during the molding process. Align the bolt at the bottom of each rubber piece with the corresponding hole on the special rim and fix it with nuts to obtain the tire assembly. Articulated tires can be made by molding or pouring, and the material is natural rubber or styrene-butadiene rubber. Polyurethane vinegar cannot be widely used for the time being because of its high cost. The number of joints depends on the tire size. After these joints are damaged, they can be taken down separately for renovation or replacement.
According to the above classification of safety tires, articulated industrial tire/rim system should belong to special rim+multi-cavity type. Airbos: Articulated tires have the following excellent properties: (1) The service life is 4.5 times that of ordinary tires, and the tread thickness remains 75% after using 12 months; (2) Stiffness is 23. Compared with pneumatic tires and solid tires, it is 5% higher and 100% respectively, and the rolling resistance is reduced by 50%-58%; (3) Shock absorption 1. 85 times that of 52 1. pneumatic tire; (4) The traction is 37% greater than that of pneumatic tires.
Airbos: The sales of articulated industrial tire/rim system was 3 million dollars in the first year of production, and by the end of 1997, it had increased to more than 300 million dollars, and the specifications had also increased from 3 to 27. Excluding the sales in Europe and Asia, it once occupied 90% of the agricultural machinery tire market in North America, but the market has shrunk in recent years.
From the development and application of safety tires abroad, whether it is self-sealing or supporting, it is a complete change to the original tire structure. At present, the supporting safety tires commonly used in high-end cars are temporary solutions rather than permanent solutions. They can only ensure that the tire runs at a certain speed and within a certain range in the case of air leakage, but they have not fundamentally solved the problem of air leakage. They also need special tires and special rims to be used with TPMS, so it is difficult to apply them to existing vehicles and tires, and the use cost is very high. Gen* Seal of European A.G. and Tiger Claw NailGard of French Michelin have solved the problem of air leakage, but they also belong to special structure tires. Although it was once popular in the 1990s, it has gradually faded out of the market, and it is difficult to apply it to the existing ordinary tires.