New energy vehicles has now become the automotive industry forward-looking, and the new energy-driven technology models and traditional internal combustion engine vehicles with no small differences, but there is a kind of drive technology has great prospects for development, this is the wheel motor technology.
-wheel motor Technical Overview
-wheel motor technology, also known as a wheel built motor technology, which is most characteristic of the power transmission and the brake device are integrated into the hub, so the electric vehicle mechanical parts greatly simplified. Wheel motor technology is not new, as early as 1900, Porsche produced the first front wheel motor equipped with an electric car in the 1970s, this technology has been used in mining trucks and other fields. For wheel motor passenger cars used, Japanese manufacturers to carry out research and development for the technology earlier, the current leader, international auto giants including General Motors, Toyota, are also all been involved in the technology. Currently there are own-brand car makers began the development of this technology, in 2011 Shanghai auto show Ruiqi X1 extended-range electric car on the use of in-wheel motor technology.
The in-wheel motor drive system of the motor rotor type divided into two main structural types: the inner rotor and the outer rotor type. Wherein an outer rotor type motor using the motor at maximum speed 1000-1500r / min, no reduction means, the wheel speed and the same low speed rumor promoter; and the inner rotor type is used within a high speed rotor motor, with a gear ratio of the gear unit , to obtain higher power density, the motor speed up to 10000r / min. With the advent of more compact planetary gear reducer, the inner rotor type in-wheel motor is more competitive than the outer rotor type in the low power density.
-wheel motor advantages
Advantage 1: omitting a large number of transmission components, so that the vehicle simpler structure
For conventional vehicles, clutch, transmission , drive shaft, differential and the splitter are essential, and these components will not only not a light weight, so that the vehicle structure is more complex, there are also issues that need regular maintenance and failure rates. But the wheel motor to a good solution to this problem. Addition to a simpler structure than using drive-wheel motor vehicle can get a better space utilization, but also much higher transmission efficiency.
2 advantages: to achieve moreComplex driving manner
Since the in-wheel motor includes a single wheel-drive characteristics, and therefore whether it is a precursor, rear wheel drive or four-wheel drive form, it can be relatively easy to implement, full-time four-wheel drive-wheel motor very easy to implement on the vehicle. Meanwhile wheel motor through different rotational speed of the left and right wheel differential steering even reverse rotation similar tracked vehicles, the turning radius of the vehicle is greatly reduced, can be almost achieved in special cases pivot turn (but this time the steering mechanism of the vehicle and tire wear larger), for special vehicles of great value.
3 advantages: ease of using a variety of technologies of new energy vehicles
Many new energy vehicles are driven by electric, so-wheel motor drive will come in great use. Either electric or fuel cell electric vehicle, or is extended Electric Vehicles, may be hub motor as a main driving force; even for a hybrid type, can also help when used as the starting or hard acceleration wheel motor employed can be described a multi-purpose machine. Meanwhile, many techniques of new energy vehicles, such as braking energy recovery (i.e., regenerative braking) can be easily driven on the hub motor vehicle is achieved.
drawbacks wheel motor
One disadvantage: increasing the unsprung inertia mass and the hub, have an impact on the vehicle’s handling
For normal civilian vehicle for, often with some relatively lightweight material such as aluminum to make the suspension member, to reduce the unsprung mass, to enhance the response speed of the suspension. But just more substantial in-wheel motor increases the unsprung mass, also increases the moment of inertia of the hub, which for handling the vehicle is disadvantageous. However, taking into electric cars are mostly limited to the means of transport rather than the pursuit of power performance, it is not the biggest flaw.
2 drawbacks: limited electrical braking performance, to maintain the braking system operation needs to consume a lot of power
Current commercial conventional power has a lot of equipment using the principle of eddy current brake (also i.e., resistance braking) the auxiliary reduction equipment, such as trucks used in many electric retarder. And because of the energy, electric vehicles using electric brake is preferred, however, for the motor-driven vehicle wheel, due to the smaller braking capacity electric wheel motor system, not meet the requirements of vehicle braking performance, requires an additional mechanical system dynamic system, but for the average electric passenger vehicles, there is noTraditional internal combustion engine driven pumps, electric vacuum pump is required to provide the brake booster, but it has meant a greater energy consumption, even if some of the energy regenerative braking energy recovery, if you want to ensure the effectiveness of the braking system, brake system consumes energy is also an important factor affecting the electric car’s mileage.
In addition, the harsh operating environment of the hub motor, faces many effects of water, dust, etc., also has a high sealing requirements while at the design needs to consider heat-wheel motor separately.