Automobile tire knowledge

Tire science knowledge: (I) history: The tire is one of the important parts of the car. It directly contacts the road surface and works with the car suspension to alleviate the impact of the car when driving, ensuring that the car has good seating comfort and driving smoothness; Ensure good adhesion between the wheels and the road surface, improve the traction, braking and passability of the car; bear the weight of the car, the important role of tires in automobiles has been paid more and more attention.

Long ago, tires were made of wood, iron and other materials. The first hollow wheel was Robert the British in 1845. Invented by Thomson, he proposed to use compressed air to fill the elastic bladder to ease the vibration and shock during movement. Although the tires at that time were made of leather and rubberized canvas, these tires already showed the advantage of low rolling resistance.

According to this principle, 1888 John. Dunlap made rubber hollow tires, and then Thomas made rubber hollow tires with valve switches. Unfortunately, because the inner layer did not have canvas, it could not maintain a certain cross-sectional shape and cross-sectional width. With the emergence of automobiles in 1895, pneumatic tires have been widely developed. The first sample of automobile tires appeared in France in 1895. This is a single-tube tire made of plain canvas, although it has tread rubber and no pattern.

It was not until 1908 to 1912 that the tires had significant changes, that is, the tread rubber had a pattern to improve the performance, which opened up the history of the tire tread pattern, and increased the cross-sectional width of the tire, allowing lower The internal pressure to ensure better cushioning performance. In 1892, Britain's Burley Mill invented the cord, 1910 for production, this achievement in addition to improving the quality of the tire, expand the tire variety, but also make the outer tire with the possibility of molding.

With the improvement of tire quality requirements, the quality of cord fabric has also been improved. Cotton cord fabric is replaced by rayon. At the end of the 1950 s, rayon was replaced by nylon and polyester cords with better strength and higher heat resistance. With the development of radial tires, steel cords have strong competitiveness. Matt created carbon black reinforced rubber in 1904. It was used on a large scale to strengthen the tread rubber after the tire was used with cord fabric. Before that, canvas was damaged faster than tread in tire use. The amount of carbon black in the rubber compound increased rapidly. In the 1930 s, the amount of carbon black used in every 100 parts of raw rubber was only about 20 parts. At this time, carbon black was mainly used on the tread, and the carcass was not used. Now it has reached more than 50 parts.

Before the tread was mixed with carbon black, the tire was polished only about 6000km. After mixing carbon black, the mileage of the tire was quickly improved significantly. Now a set of truck tires can travel about 100000km, on good roads, even up to 200000km.

From 1913 to 1926, the invention of cord and carbon black tire technology laid the foundation for the development of the tire industry. The standardization of the outer edge of the tire, the gradual improvement of the manufacturing process, the production speed is higher than before, and the output of the tire is increasing day by day.

With the development of the automobile industry, tire technology has been continuously improved and improved. For example, car tires transitioned from low-pressure tires to ultra-low-pressure tires from the early 1920 s to the mid-1930s; tires gradually transitioned to wide rims in the 1940 s; tubeless tires in the late 1940 s The emergence of low-profile tires in the late 1950 s and so on. The emergence of many new technologies is nothing more than the radial structure tire pioneered by the French company Misilin in 1948. This kind of tire is known as the tire industry due to the significant improvement in service life and performance, especially when driving. Revolution, here is a brief introduction to the main characteristics of today's development of tires.

Radial tire: The characteristic of this tire is that the direction of the cord arrangement is consistent with the radial section of the tire (that is, the crown angle is zero degrees). Due to the arrangement of the cord, the strength of the cord can be fully utilized. The number of ply layers of radial tires is generally reduced by about 40-50% compared with ordinary diagonal tires. The cord is connected in the circumferential direction only by rubber.

Compared with ordinary diagonal tires, radial tires have greater elasticity and good wear resistance, which can increase the service life of the tire by 30-50%, have low rolling resistance, can reduce automobile fuel consumption by about 8%, have good adhesion performance, and good cushioning performance., Large carrying capacity, not easy to puncture and other advantages. The disadvantages are: the sidewall is easy to crack, due to the large side deformation, the lateral stability of the car is poor, and the manufacturing technology requirements and cost are high.

Tubeless tires: Tubeless tires are different from ordinary tires in that there is no inner tube, and air is directly pressed into the outer tire, so there must be a good seal between the tire and the rim. Tubeless tires are similar in appearance and structure to tubeless tires. The difference is that a rubber sealing layer with a thickness of about 2-3mm is added to the inner wall of the tubeless tire to seal the air. It is vulcanized. The method adheres to it. When the tire is punctured, it is tightly wrapped with the puncture because it is in a compressed state, so it can not leak for a long time, even if the puncture is pulled out, it can also temporarily maintain the air pressure in the fetus.

Tubeless tires have concentric annular grooves on the bead. Under the action of air pressure in the tire, the grooves can reliably press the bead on the rim edge to ensure sealing. The rim on which the tubeless tire is installed is airtight, with a sloping bottom and a smooth paint layer.

The valve is directly pressed and fixed on the rim, and the rubber gasket is used for sealing. Tubeless tires have the advantages of good air tightness, good heat dissipation, simple structure and light weight.

The disadvantage is that it is more difficult to repair on the way. Wide-section tires: With the increase in vehicle speed, it is required to lower the center of gravity of the vehicle and improve the handling performance. This requires improving the lateral stability of the tires and the adhesion to the road surface to ensure driving safety at high speeds. The emergence of cross-section tires has become an inevitable trend.

The ratio (H/B) of the cross-sectional height (H) to the cross-sectional width (B) of the tire is an important parameter representing the structural characteristics of the tire. It is called the aspect ratio of the tire, and some people call it the aspect ratio. Since the 1920 s, the outer diameter of car tires has been reduced by 25%, the diameter of rims has been reduced by 35%, the width of tires and rims has nearly doubled, and the aspect ratio of tires has been continuously reduced, reaching 0.5 for cars. Up to 0.4, especially wide tires match high-end cars, which are more beautiful and generous.

The history of the development of automobile tire production shows that the first 50 years are mainly to solve the problem of how to improve the service life of tires. In recent years, due to the increasingly demanding requirements of automobile manufacturing and transportation departments on tires, the focus of tire research has changed.

4. How to maintain and check the wheels of trucks

The service life of tires is largely determined by the following factors:

1 Tire inflation pressure

Too low or too high tire inflation pressure will shorten the life of the tire and have a negative impact on the driving performance of the car. The inflation pressure should be checked twice a month, and it should also be checked before each long-distance driving. The spare tire should not be forgotten when checking. The inflation pressure is checked when the tire is cold.

2 The impact of driving style on tires

3 Rapid turns, sharp acceleration, violent braking, etc. will accelerate tire wear.

4 Vehicle balance

Wheel imbalance will increase the impact on the steering gear, suspension system and tire wear. Therefore, the wheels of the new car and the wheels after each repair should be balanced.