What is hub motor technology?

Hub technology, also known as motor technology built into wheels, is characterized by integrating power, transmission and braking devices into the hub, so the mechanical part of electric vehicles is greatly simplified. Hub motor technology is not new. As early as 1900, electric vehicles with hub motors on the front wheels have been manufactured. In 1970s, this technology was applied to the field of mine transport vehicles. As for the hub motor used in passenger cars, Japanese manufacturers developed this technology earlier and are currently in a leading position, and international automobile giants including GM and Toyota are also involved in this technology. According to the rotor type of the motor, the hub drive system is mainly divided into two structural types: inner rotor type and outer rotor type. Among them, the outer rotor type adopts low-speed outer rotor motor, with the highest speed of 1000- 1500r/min, without reducer, and the wheel speed is the same as that of the motor; The inner rotor type adopts high-speed inner rotor motor and reducer with fixed transmission ratio. In order to obtain higher power density, the speed of the motor can be as high as 10000r/min. With the appearance of more compact planetary gear reducer, the inner rotor hub motor is more competitive than the low-speed outer rotor motor in power density. For traditional vehicles, clutches, gearboxes, transmission shafts, differentials and even transfer cases are basically indispensable. These components are not only light in weight, but also make the structure of the vehicle more complicated. At the same time, they also have problems of regular maintenance and failure rate. However, the hub motor solves this problem very well. In addition to the simpler structure, the vehicle driven by in-wheel motor can obtain better space utilization and the transmission speed must be much higher. Because the in-wheel motor is driven independently by a single wheel, whether it is front drive, rear drive or four-wheel drive, it can basically be easily realized, and it is very easy to realize full-time four-wheel drive in a vehicle driven by in-wheel motor. At the same time, the hub motor can realize differential steering or even reverse direction similar to that of a tracked vehicle through the different speeds of the upper and lower wheels, which greatly reduces the turning radius of the vehicle, and can almost realize in-situ steering under special circumstances (but the steering mechanism and tires of the vehicle are greatly worn at this time), which is very valuable for special vehicles. The following is the hub motor technology: 1. Modern cars drive wheels through engines, which leads to huge power loss. What if the wheels can generate electricity and drive directly? Just like human limbs, the strength of each limb will be relatively faster and the loss of strength will be small. In fact, this idea is feasible, and now it has been developed, that is, hub motor technology; 2. In short, the hub motor technology is very simple, that is, each hub generates electricity to drive the whole car forward. Because there is no need for differential, half axle or even two-stage transmission, the transmission efficiency and dynamic performance of the car are higher. And because it is a four-wheel drive, it has a very good performance in various terrains; 3. The advantage of in-wheel motor technology is that each wheel can be completely controlled independently, so the functions of wheel-to-wheel difference and torque vector control can be easily realized, which is very important in many off-road terrain. Moreover, because there is no need for reducer, transmission shaft and differential, the vehicle also has more flexible space design; 4. But the hub motor also has many disadvantages, because the hub motor needs to concentrate the equipment on the hub, which is a great test for the suspension of the chassis. At present, the lightest in-wheel motor has a unilateral mass of 34KG, which is a great challenge to the stability and comfort of the chassis and an urgent problem to be solved. Another disadvantage is that off-road performance is actually very worrying. The advantage of hub motor can be said to be off-road, but the disadvantage is also here. Because the hub motor and the hub are integrated, the extremely harsh working environment on off-road sections is a great challenge to the waterproof, corrosion resistance, cooling and heat dissipation of the hub motor. Therefore, this technology still needs to be developed, but it is optimistic because it is really useful.