The significance of the existence of hydrogen energy vehicles is the same as that of electric vehicles, and it is the ultimate solution to the emission problem. Under the global theme of promoting low carbon and environmental protection, hydrogen-powered vehicles have the advantages of zero fuel consumption, zero emissions and low noise of pure electric vehicles, and the core part is fuel cells. We can understand Mirai as an electric car, but it uses fuel cells instead of bulky and inefficient lithium-ion batteries. Hydrogen fuel cell vehicle uses the charge transfer in the process of hydrogen-oxygen chemical reaction to form current, which makes the motor run, thus driving the vehicle.
As far as the core structural components are concerned, Mirai is obviously more complicated than hybrid electric vehicles and pure electric vehicles. The whole power system takes the fuel cell stack as the core, without the traditional gasoline engine, transmission, fuel tank and large-area lithium-ion battery. In the engine compartment is the motor and its control unit. A Ni-MH battery pack and two high-voltage hydrogen storage tanks are placed on the rear axle of the car body. In Mirai, there is no need to consider the problem of refueling or charging, and the only "fuel" consumed by driving is hydrogen.
Hydrogen is a gas at room temperature, with low density, not easy to liquefy and easy to burn. Therefore, how to store hydrogen safely has become the primary consideration of hydrogen-powered vehicles. Toyota Mirai installed two high-pressure hydrogen storage tanks, one large and one small, on the rear axle of the car body, and designed them into three layers of oval capsules made of different materials.
The tank body of the high-pressure hydrogen storage tank is lined with a plastic sealing liner, and the plastic sealing liner is wrapped with a carbon fiber reinforced plastic compression layer, and a shock absorption protective layer made of glass fiber material is arranged outside the compression layer. The fiber particles of each layer are additionally optimized according to the position of the tank, so that the fibers follow the direction of pressure distribution and improve the protective layer effect. The capacity of the two hydrogen storage tanks * * * is 122.4 liters (60 liters for the front tank and 62.4 liters for the rear tank). It is stored at 700 atmospheres and can hold about 5 kilograms of hydrogen at most.
However, in order for the fuel cell stack to react normally to generate electricity, it is necessary to add oxygen, and only by bringing in air can the effect be achieved. The air intake grille will form a channel. After air enters the fuel cell stack, hydrogen will combine with oxygen in the air to generate current, and the only "waste" in the whole process is pure water.
When the vehicle starts, the current generated by the fuel cell stack will not only be supplied to the motor-driven vehicle, but also be partially stored in the Ni-MH power battery located above the rear axle. This 1.6 kWh battery is exactly the same as the Camry hybrid, which plays the role of power and energy storage. When the vehicle load is low, the power supply can be used alone to drive the vehicle forward. If the vehicle has a large power demand, the motor and Ni-MH battery can be met by dual power supply. When the vehicle decelerates and brakes, the kinetic energy recovered by the motor will "charge" the Ni-MH battery pack.
Aside from the external factors of fewer hydrogen refueling stations, the charging speed of hydrogen fuel is much faster than that of electric vehicles. Taking Mirai as an example, it takes only 3 minutes to fill up with hydrogen fuel and can travel about 650km；; In contrast, the Tesla Model S has a cruising range of about 500km after being fully charged, but the charging time is 5 hours faster at the earliest.
Through this explanation, I believe everyone has a certain understanding of the working principle of Toyota hydrogen-powered vehicles. If we only look at energy efficiency and environmental protection, hydrogen power should be equally divided in the world, even if it cannot replace the status of electric vehicles. Obviously, this is not the case. Now the biggest threshold that hinders the popularization of hydrogen electric vehicles is cost. Here, I have to marvel at Toyota's cost reduction measures. In 2008, the cost of fuel cells for vehicles on the concept car FCV reached $654.38 million+$00,000, but now it can be reduced to $50,000 in Mirai, a drop of 95%. From threat to realization, less than a year. No wonder it is called "black technology" by netizens.
In fact, hydrogen power is not a new concept. In the early years, many manufacturers have done related research and development, and some of them are developing in the direction of fuel-fired internal combustion engines. However, in the end, Toyota was the first to dare mass production, and the rest was still trapped in the cost of the whole vehicle. However, we can see that the international attitude towards hydrogen fuel cells is quite positive. Britain will subsidize half of the construction and operation costs of hydrogen refueling stations; Germany and Japan plan to build 1000 hydrogen refueling stations; California plans to achieve 10000 hydrogen-powered vehicles in 20 15 years. In addition, major manufacturers adopt alliance cooperation mode. At present, Honda-GM, Toyota-BMW and Nissan-Ford-Daimler are representative combinations, all of which are aimed at accelerating the popularization of hydrogen fuel cells.
In this list, we also saw some domestic brands. By the way, the country actually pays special attention to hydrogen fuel cell technology. In 20 13, the State Council issued relevant policies, hoping that manufacturers can jointly research and develop with major scientific research institutions to form a fuel cell power system technology platform for passenger cars and commercial vehicles with independent intellectual property rights. At that time, SAIC's response plan was to realize the industrialization of fuel cell vehicles in 20 15 years and put them on the market in pilot cities such as Beijing, Shanghai and Dalian. The planned production capacity is 1000 vehicles, and the cost of the whole vehicle is reduced to less than 500,000.
Unfortunately, these seemingly ambitious plans can't compete with the cruelty of reality in the end. At present, the core technical level and related experience accumulation of local brands are still quite lacking, mainly in product reliability and life. However, this situation may be improved, because Toyota has opened more than 5,000 fuel cell patents, with the aim of globalizing technology, thus accelerating the construction of hydrogen refueling stations in various countries.
However, Toyota does not seem to regard China as a key market for hydrogen-powered vehicles. The reason may be that the production capacity of hydrogen-powered vehicles is not high. Faced with a market in short supply, priority will be given to countries or regions with strong policy support and enthusiasm for this technology. Although the China government has issued policies to promote the development of fuel cells, there are not many practical support actions. Both enterprises and consumers can only face it with a "wait-and-see" attitude, which ultimately delays time.
Finally, it is suggested that local car companies take seriously the opportunity of Toyota's patent opening, because this is not like the patent blockade of hybrid power in the past, which is conducive to further improving the product level by learning mature technologies. In addition, state subsidies have always been more inclined to local brand car companies, and whoever has reliable product quality will win the hearts of the people.