PROFESSIONAL TYRE MANUFACTORY

Before answering this question, first of all, we need to explain the "hub motor". To put it bluntly, the "hub motor" is a motor designed by integrating the "power system, transmission system and braking system" of the car.

Hub motor technology is not a new thing. As early as 1900, Porsche first manufactured electric vehicles equipped with hub motors on the front wheels. In the 1970s, this technology was applied in mining vehicles and other fields. For the hub motor used in passenger cars, Japanese manufacturers have developed this technology earlier and are in the leading position. International automobile giants including GM and Toyota have also set foot in this technology.

Advantages and disadvantages of hub motor

Advantage 1: omit a large number of transmission parts, make the vehicle structure more simple

For traditional vehicles, clutch, transmission, transmission shaft, differential and even transfer case are essential. These components are not only heavy, but also need regular maintenance and failure rate. But the hub motor is a good solution to this problem. In addition to the simpler structure, the vehicle driven by hub motor can get better space utilization, and the transmission efficiency is also much higher.

Advantage 2: a variety of complex driving modes can be realized

Because the wheel motor has the characteristics of independent driving of a single wheel, it can be easily realized in the form of front drive, rear drive or four-wheel drive. It is very easy to realize the full-time four-wheel drive in the vehicle driven by the wheel motor. At the same time, hub motor can realize differential steering similar to tracked vehicle through different rotational speeds of left and right wheels or even reverse rotation, greatly reducing the turning radius of the vehicle. In special cases, it can almost realize in-situ steering (but at this time, the wear of vehicle steering mechanism and tire is greater), which is very valuable for special vehicles.

Advantage 3: easy to use a variety of new energy vehicle technology

Many new energy vehicles are driven by electricity, so the wheel motor drive is in great use. Hub motor can be used as the main driving force for pure electric vehicles, fuel cell electric vehicles and extended range electric vehicles; Even for hybrid vehicles, the hub motor can be used as a starting or accelerating power, which can be described as a multi-purpose machine. At the same time, many new energy vehicle technologies, such as braking energy recovery (regenerative braking) can also be easily realized in the wheel motor-driven vehicle.

Why can't such excellent technology be popularized? In fact, for hub motors, the precise control of four-wheel speed that some people worry about is not a problem at all. It's just a function that can be realized by an ordinary electronic control system, and it's much easier to realize than traditional cars. Bosch, Daimler, GE and others abroad can provide reliable solutions, and there are several domestic ones, such as Asia Pacific motors. Secondly, in extreme cases, such as a motor failure, the system can easily adjust the speed of other hub motors, so that the vehicle will not lose control.

The real problem is:

1. Although the quality of the whole vehicle has been greatly reduced, the unsprung quality has been greatly improved, which will have a great impact on the control, comfort and suspension reliability of the whole vehicle!

2. Cost. The price of four-wheel hub motor with high conversion efficiency and lightweight remains high, which is not enough to attract manufacturers to carry out transformation.

3. Reliability. If you put the precise motor on the wheel hub, even if you don't consider the problems caused by long-term severe up and down vibration and bad working environment (water and dust), you should also consider that the wheel hub is the part that is easily damaged in the accident, and the maintenance cost is high.

4. The problem of braking heat and energy consumption. The motor itself is heating. Due to the increase of unsprung mass, the braking pressure is greater and the heating is greater. Such a concentrated heating has very high requirements on the braking performance. At present, we can only rely on water cooling and oil cooling. And the electric braking system will increase energy consumption, in the current situation that the battery is difficult to break through, this problem is more prominent.

Hub motor technology does have good advantages. It can not only save a lot of space, but also improve the transmission efficiency. It is a good direction for the development of new energy vehicles. But at present, there are still many problems in this technology, such as the working environment of the wheel is too complex, the durability is not guaranteed, the high-speed vibration, noise and the optimization of braking and suspension, etc. These are all problems that engineers need to solve step by step.