The rapid development of electric cars has brought a negative impact on the transmission industry. However, as the development trend of multi-speed transmissions for electric cars gradually becomes clear, it is estimated that the value of electric car transmissions will increase substantially. For related parts and components companies, this is a "territory" that must be seized.
Multi-speed transmission of electric cars has become an inevitable trend
Since the birth of electric cars, the issue of whether electric cars need transmissions has caused many controversies in the industry. With the passage of time, the answer to this question gradually became clear. An electric car can have no transmission, but with the correct transmission, an electric car will add a lot of points.
As for traditional fuel cars, they cannot travel normally without a transmission. Specifically, because the reasonable speed of the engine is relatively narrow (usually around 1000-4000 rpm), the speed is too low to be unable to output torque, while the speed is too high to reduce power. Therefore, it is necessary to adjust the reduction ratio through the transmission to keep the speed within a reasonable working scale. Electric cars are different. They can operate as usual without a transmission. The primary reason is that the motor has a wide working scale (usually between 0-15000rpm), and can output large torque at low speed or even at zero speed.
At present, electric cars on the market mainly choose the structure of a single-stage reducer with a motor supporting. It is understood that the single-stage reducer does not require shifting organization, synchronizer and clutch, and has a relatively simple structure and is easy to implement, so it is widely used by car companies.
However, for electric cars, a single-stage reducer is not a good solution. The single-stage reducer has the following main disadvantages: First, the single-stage reducer cannot consider the efficient operation of the motor under the conditions of low-speed starting and high-speed travel. The low motor power affects the cruising range of electric cars; secondly, the torque is not available when traveling at high speeds. In the output scale, the acceleration is weak; in addition, compared with the two-speed transmission, the single-stage reducer has significantly higher requirements on the motor, which requires the motor to have higher power and higher speed.
Motor power curve: the blue area is the motor low power area (80%-90%), the red area is the high power area (90%-93%)
In comparison, multi-speed transmissions have many advantages. It can improve the working power of the motor and the dynamic functions of the car, while reducing the functional requirements of the motor. It only needs to be equipped with a motor with a smaller volume, weight and power to meet the demand. Put forward requirements for the power function of the car, thereby reducing the cost of the motor. In addition, the multi-speed transmission can also reduce the power consumption of electric cars and increase the cruising range. Experts in this field, Zhou Shijian, said in an interview with Gascoo that compared with a single-stage reducer, a two-speed transmission can save up to 13% of electricity. According to Schaeffler's research, the two-speed transmission can increase the mileage of the vehicle by 3%-5%, and shorten the speed of 0-100km/h by about 30%.
Based on this, with the increase in user demand for electric cars, the development trend of electric car multi-speed gearboxes has gradually become clear. The multi-speed transmission of electric cars will undoubtedly be a trend. "We need multi-speed transmissions to adapt and improve the overall functions of electric cars." Yang Lianghui, head of the electric drive business of the National New Energy Car Technology Innovation Center, pointed out that two-speed transmissions are the future An important direction.
Multi-component companies began to deploy, their advantages are different
At present, single-stage reducers are the first choice for electric cars, which has a negative impact on transmission companies. Although such enterprises have sufficient strength to supply single-stage reducer products for electric cars, the value of single-stage reducers to electric cars is far lower than that of traditional transmissions. According to calculations by related organizations, the current unit price of single-stage reducers used in pure electric and series hybrid power is mostly between 1,000 and 2,000 yuan, which is much lower than that of AT/DCT and often between 8,000 and 10,000 yuan.
Compared with a single-stage reducer, a multi-speed transmission has greater bicycle value. This means that as the development trend of electric car multi-speed gearboxes becomes more and more clear, it is estimated that the value of electric car gearboxes will be greatly increased, and gearbox companies will also benefit from it. This is also an important reason why many car and component companies are racing to release multi-speed transmission products for electric cars.
Specifically, because the energy consumption of the electric motor changes less than that of the engine, electric cars do not need to use 6 to 10 gears to match the operating conditions of the engine, just like a fuel car transmission. Taking into account the overall cost and functions, the current multi-speed transmission of electric cars is the first choice of two-speed transmission. In the medium and long term, some electric car transmissions may be developed in the direction of three-speed or four-speed transmissions. The primary reason is that adding the gears of the transmission can make the pure electric car have stronger climbing ability, lower energy consumption, and stronger endurance.
The layout of the transmission company is consistent with this, and currently the main focus is on two-speed transmission products. However, the two-speed transmission products of different companies choose different technical routes. It is understood that, from the structural point of view, there are currently four main routes for the two-speed transmission of pure electric cars: synchronizer shift structure, single clutch structure, double clutch structure, and planetary gear structure.
According to data from Great Wall Securities, the synchronizer shift structure is simple and compact, and the transmission power is high, but the power supply is interrupted when shifting, and it is used in cooperation with the rear axle engine drive system. The other three technical paths can deal with the problem of shifting and power failure. In the meantime, the advantages of the planetary gear structure are more prominent, and are more favored by the industry. The structure has the advantages of compact structure, strong impact resistance, large transmission ratio and high transmission power.
From another perspective, traditional transmissions are divided into manual transmissions and active transmissions. There are four types of active transmissions: AT, AMT, continuously variable transmission and DCT. For electric cars, there seem to be many solutions for multi-speed transmissions. From the perspective of the overall layout of the company in this field, it also includes AT, AMT, DCT, CVT and other directions.
