The use of reduction gears can save costs, and the benefits of using reduction gears are many. First, it can reduce costs, and secondly, it is easier to lay out. We know that electric vehicles have particularly good acceleration performance. Moreover, this is also a parameter that all manufacturers and consumers attach great importance to. Well, the easiest way to speed up acceleration is to use a high-power motor. However, in practice this is not allowed. Because the motor power is increased, it will not only increase its size, weight, cost, and it is not easy to layout. What's more, large motors will have more time to work in the inefficient range in daily operation. Just like you loaded the 6.0-liter engine of the W12 on the Chery QQ, there is power. But the idle fuel consumption of this engine is higher than the engine of chery's original car 3000 rpm, and your small fuel tank will be halved by stepping on the throttle of both feet. It can't be used at all. The efficiency of the entire electric motor is not bad, but for a car powered by a battery, it is necessary to consider the impact of such an efficiency difference on the endurance.
So, what about motors that want to speed up performance and don't want to use power too much? The answer is to achieve good acceleration by combining a small motor with another reduction gear. When driving a fuel car, we know that "there is not enough horsepower, and the speed will gather". That is to say, at low volumes, even at high speeds, better dynamics can be obtained. On the other hand, the use of reduction gears in electric vehicles is also this meaning. What's more, the most indispensable thing about the motor is the speed. At present, the maximum speed of the motor used in electric vehicles is generally about 15,000 rpm-20,000 rpm. If the engine of the fuel vehicle can reach 20,000 rpm, it can drive to 170 km / h in one gear. In addition, with smaller motors, it is easier for the motor to work in a more efficient range during daily operation, which also helps to increase the endurance.
Therefore, the current electric car is such a model, the power of the electric motor is distributed to the drive wheel through the reduction gear with a differential. In addition, not only electric vehicles, but also electric tricycles and electric small four-wheelers that are commonly found on the street are also the same structure. 2, the need to install a differential Because the car has different speeds of the left and right wheels when turning, the power of all cars is transferred to the two drive wheels after the differential is distributed. This ensures that the drive wheels are powered when cornering, and the two drive wheels rotate normally at different speeds. The car drove smoothly and flexibly.
When the motor is connected directly to the drive wheel, there are two options. One shown on the left side of the figure above, the motor drives the axle through a reduction gear, and the axle connects the two drive wheels. However, in this case, the speed of the two driving wheels is exactly the same, and the driving is unstable when turning. As shown on the right side of the figure above, there is also a method of using one motor for each drive wheel, and the different speeds of the two drive wheels are achieved by controlling the speed of the motor when rotating. But this control is very complicated, and the cost is high, and the control is difficult. Therefore, the best way is to transfer the power of the motor to the differential through the reduction gear, and then distribute it to the two wheels through the differential.