The reason why maglev trains cannot be widely used

The maglev train is a high-tech means of transportation that uses the attraction and repulsion of magnetic poles. To put it simply, the repulsive force makes the train hang and the attraction makes the train move.

The maglev train is equipped with electromagnets, and the bottom of the railway is equipped with coils. After the power is applied, the polarity of the magnetic field generated by the ground coil and the polarity of the electromagnet on the train always remain the same, and the two are "repulsive", and the repulsive force makes the train levitate. The rails are also equipped with coils on both sides, and the alternating current turns the coils into electromagnets.

It interacts with the electromagnets on the train to make the train move forward. The electromagnet (n pole) of the locomotive head is attracted by the electromagnet (S pole) a little earlier on the track, and at the same time repelled by the electromagnet (n pole) a little later on the track, and the result is a "push" and a "pull". When the maglev train is running, it maintains a certain gap (generally 1 10cm) with the track, so it runs safely, smoothly and comfortably, without noise, and can realize fully automatic operation.

The service life of maglev trains can reach 35 years, while ordinary wheel-rail trains are only 20 to 25 years. The lifespan of the maglev train track is 80 years, and the ordinary rail is only 60 years. In addition, the maglev train reached its top speed within 39 seconds of starting, and the current top speed is 552 kilometers per hour.

According to German scientists**, by 2014, the maglev train will be able to reach speeds of up to 1,000 kilometers per hour after adopting the new technology. The maximum speed of a general wheel-rail train is 300 kilometers per hour.

Maglev trains are divided into two categories: normal and superconducting. The normal conductive type, also known as the normal conductive magnetic attraction type, is represented by the German high-speed constant conduction maglev train Transrapid, which uses the principle of electromagnetic attraction of ordinary DC electromagnets to suspend the train, and the suspended air gap is small, generally about 10 mm. The speed of the high-speed maglev train can reach 400 500 kilometers per hour, which is suitable for long-distance rapid transportation between cities.

The superconducting maglev train is also called the superconducting maglev type, which is represented by the Japanese maglev. It is the use of superconducting magnets to generate a strong magnetic field, the train interacts with the coil arranged on the ground when it is running, and produces an electric repulsion to suspend the train, and the suspension air gap is large, generally about 100 mm, and the speed can reach more than 500 kilometers per hour. These two kinds of maglev trains have their own advantages and disadvantages and different economic and technical indicators, Germany favors the former and concentrates on the development of high-speed maglev technology; Japan, on the other hand, is optimistic about the latter and is fully committed to high-speed superconducting maglev technology.

The cost is too high.

It is estimated that the operating costs are too high.

Advantages: fast, low consumption, environmental protection, safety;

Cons: technical problems, funding.

Constant conductive maglev trains can reach 400 to 500 km/h, and superconducting maglev trains can reach 500 to 600 km/h. Its high speed gives it an advantage over flying in distances between 1000 and 1500 km. Due to factors such as no wheels and no friction, it consumes 30% less electricity than the current state-of-the-art high-speed trains.

At a speed of 500 km/h, the energy consumption per seat-kilometer is only 1 3 to 1 2 of that of an airplane, which is 30 per cent less energy than a car. Because there is no wheel-rail contact, the vibration is small and the comfort is better, but the large bumps also require extremely high maintenance costs for vehicles and rails. The maglev train does not rub against the track when it is running, and the noise emitted is low.

Maglev trains are generally elevated by more than 5 meters through flat land or over hills, which inevitably causes damage to the ecological environment caused by digging mountains and trenches. Maglev trains run on rails and are configured according to the fire protection standards of aircraft.

Its classification: 1. Constant attraction type.

The normal conduction attraction maglev train is based on the constant conduction magnet and the guide rail as the magnet conductor, and the air gap sensor is used to adjust the suspension gap between the train and the line, in general, the suspension gap size is about 10 mm, and the running speed of this maglev train is usually in the range of 300-500 km h, which is suitable for intercity and suburban transportation.

2. Superconducting repulsive type.

The superconducting repulsive maglev train is the use of superconducting magnets and low-temperature technology to achieve suspension between the train and the line, the size of the suspension gap is generally about 100mm, this maglev train does not levitate at low speed, and only levitates when the speed reaches 100 km h. It can reach a maximum operating speed of 1000 km h, and of course its construction technology and cost are much higher than that of the normally conductive attraction maglev train.

Advantages of maglev trains.

The maglev train has many advantages: the train runs suspended above the rails, the rails are not in contact with the vehicles, not only the running speed is fast, it can exceed 500 kilometers per hour, but also the operation is stable and comfortable, and it is easy to realize automatic control; No noise, no harmful exhaust gas, conducive to environmental protection; It can save construction costs; Low operation, maintenance and energy costs. It is an ideal super special express train in the 21st century, and countries around the world attach great importance to the development of maglev trains.

At present, China and Japan, Germany, the United Kingdom, the United States and other countries are actively studying this kind of car. Japan's superconducting maglev train has already undergone manned tests and is about to enter the practical stage, running at speeds of more than 500 kilometers.

So far, it can be said that the maglev train track technology is in China, and the maglev train technology is still in Germany, and the imported products cannot be introduced technology. China's wheel-rail railway technology has a history of nearly 100 years, forming an industrial army specializing in locomotive design, scientific research and innovation, and an industrial chain of more than 400,000 people with decades of design, manufacturing, operation and maintenance. Magnetic levitation technology is in the hands of a few experts and professors, and it does not have the conditions for application.

Maglev trains need to be elevated, and the winding of the elevated beams must be less than 1 mm, therefore, the viaduct span should generally be less than 25 meters, and the pier foundation should be more than 30 meters deep. Therefore, a retaining wall of more than 200 kilometers should be formed on the ground from Shanghai to Hangzhou. In addition, due to the influence of operational dynamics, no other buildings are allowed within 100 meters on each side of the track.

The construction of Shanghai-Hangzhou maglev covers a large area and has a relatively large impact on the environment.

Disadvantages of maglev trains.

In 2006, a German maglev control train collided with a maintenance vehicle during a test run, and it was reported that a total of 29 people on board were killed, 23 died on the spot, 25 actually died, and 4 were seriously injured. This shows that the braking ability of the maglev train in sudden situations is unreliable, and it is not as good as the wheel-rail train. It is dangerous to have no wheels in a vehicle on land.

Because the train has to descend from a lot of momentum to a standstill, it has to overcome a lot of inertia, and it can only be overcome by the braking force of the wheels and tracks. Maglev trains have no wheels, and if there is a sudden power outage, it is dangerous to rely on sliding friction. In addition, the maglev train is elevated, and it is difficult to rescue at a height of 5 meters in the event of an accident, and it is difficult to tow out of the accident scene without wheels; If there is a power outage in the section, it will be difficult for other vehicles and cranes to get close.

1.Merit.

1) Fast speed. Maglev trains are the only ground passenger transport vehicles that can reach operating speeds of up to 500 kilometers per hour. This means that for inter-city travel between cities with a distance of 500 km to more than 1,000 km, maglev trains are completely comparable to airplanes in terms of travel time and travel quality.

2) Low relative energy consumption. At a speed of 500 kilometers per hour, the energy consumption per seat kilometer of the maglev train is only 1 3 to 1 2 of that of an airplane, which is 3 percent less than that of a car.

3) Easy to turn, able to climb, flexible line selection, strong adaptability. The maglev high-speed line requires a much smaller turning radius than conventional railways and has a climbing capacity of up to 10. This allows the maglev line to be more flexible to adapt to the terrain, which can reduce the cost of construction.

4) Low noise. Due to the absence of friction between wheels and rails, the noise of maglev trains is lower than that of conventional railways at the same speed.

5) No pollution. Since the maglev train is powered by electricity, its development is not limited by the energy structure, especially the fuel **; At the same time, there is no exhaust gas along the track, and it is a veritable green means of transportation.

6) Safe, comfortable and less maintenance. The maglev train is not easy to derail in terms of structure, and the propulsion mode ensures that it is not easy to crash. The maglev train has no contact between the wheels and the rails, the vibration is small, the comfort is good, its work belongs to the wear-free operation, the maintenance is mainly focused on electronic technology, and does not require a lot of manual labor.

Maglev trainsThe operation is based on the principle of electromagnetic induction, and the reason why it is not popularized is orHigh-speed railThe development has basically been able to meet the requirements of transportation capacity, and the research and development of maglev requires a lot of capital and new infrastructure.

Maglev train is a kind of linear motor that uses the principle of electromagnetic induction.

A technique that drives a vehicle so that the train overcomes its own gravity or levitates on tracks. with intercity railways.

The difference is that maglev trains begin to run inertly after reaching a certain speed, and always need power traction. Therefore, with the increase of transportation distance, the energy consumption of maglev trains decreases.

But this distance growth is very long, and usually, in the range of 500-600 meters, maglev trains cannot be suspended, which means that the cost of the technology will be much greater than the current running rail trains.

Although high-speed rail started late in China, the current development speed of high-speed rail in China is the fastest, and the mileage and high-speed rail trains have been built.

It is also the most, the country sends about 4,300 high-speed trains every day, which fully shows that China's high-speed rail technology has been relatively mature, and some scientific research institutions are trying to use different models to improve speed.

As far as the current situation is concerned, the development of high-speed railway has been able to meet our current transportation needs, so the research and development funds for maglev are relatively insufficient, due to limited funds, in the 10 years from 2001 to 2011, there is almost no major progress in the application of high-temperature superconducting maglev.

To break through the bottleneck of the current high-speed rail speed development, we must first solve two problems. First, it is necessary to change the restriction of the wheel-rail limit of the traditional wheel-rail train and the restriction of the limit speed and fluctuation speed of the public network operation. Second, it is necessary to overcome the air resistance caused by the higher the speed of the train.

The bigger the problem, so use magnetic levitation technology.

It is the direction of the future development of high-speed rail.

The principle adopted is that there will be attraction and mutual repulsion between the electromagnetic coils, because it is difficult to break through such a speed, and then the speed needs to be grasped at about 450 kilometers per hour, and there is no way to increase the speed of operation.

The principle of mutual repulsion and attraction of magnets is utilized. Because the cost of this kind of train is relatively high, the requirements for the region are relatively high when driving.

The principle of electromagnetic induction, because there will be a high difficulty in the process of promotion, and the cost is relatively high, basically a lot of money will be wasted.

A maglev train is a type of train that is propelled by the magnetic levitation force (i.e., the attraction and repulsion of magnetism). Since the magnetic force of its orbit makes it levitate in the air, it does not need to touch the ground when walking, so its resistance is only that of air.

The maglev train uses the principle of "the magnetic poles of the same name repel each other, and the magnetic poles of the different names attract each other", so that the magnet has the ability to resist gravity, so that the car body is completely off the track, suspended about 1 cm away from the track Qioak, and drives in the air, creating a miracle of space flight almost "zero quiet ridge next to the height". Because magnets have two forms, same-sex repulsion and opposite-sex attraction, there are also two corresponding forms of maglev trains: one is a maglev train designed by using the principle of magnet homogeneous repulsion, which uses the magnetic field formed by the superconductor electromagnet on the car and the magnetic field formed by the track coil to make the car body suspend the railway; The other is the magnetic levitation train designed by using the principle of magnet opposite-sex attraction, it is to install magnets at the bottom of the car body and the top of the reverse steering on both sides, and set up a reaction plate and an induction steel plate respectively above the T-shaped guide rail and below the outrigger part, control the current of the electromagnet, keep a gap of 10-15 mm between the electromagnet and the guide rail, and balance the repulsion force of the guide rail steel plate with the gravity of the vehicle, so that the car body is suspended on the guide rail surface of the lane to run.

In layman's terms, the alternating current flowing in the coils on both sides of the track turns the coils into electromagnets. Due to its interaction with the superconducting electromagnets on the train, the train is set in motion. The train advances because the electromagnet at the head of the train (n-pole) is attracted by the electromagnet (s-pole) on the track that is a little ahead of the field, and at the same time it is repelled by the electromagnet (n-pole) that is installed a little later on the track.

When the train advances, the direction of the current flowing in the ** circle is reversed. As a result, the original S-pole coil is now an N-pole coil, and vice versa. In this way, the train is able to continue to move forward due to the change of electromagnetic polarity.