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What is China's development of new energy vehicle technology route? Has been controversial. Finally, under the direct participation of senior leaders in the country, clear the "pure electric drive" for the new energy vehicles in China's technical route, the hybrid technology line is drawn to the scope of energy-saving cars. Next, the beginning of the discussion is focused on the drive? Or distributed driver? The discussion must be divergent thinking, which is a necessary process. But in the end still want to converge. I point of view is that the current focus on the main drive, the future is distributed driven. The following discussion is for reference.

What is pure electric drive?

Driving the power of the car must be mechanical force, the current drive the mechanical force from the engine output of the mechanical force and the motor output of the two mechanical force. Other forms of mechanical force (flywheel, hydraulic, etc.) to drive the car forward, it is estimated that the product has not become a possibility.

"Pure" the basic meaning of the word is to drive the mechanical force of the car, is a single from the motor output of the mechanical force; another layer means that even if the car has an internal combustion engine in the work, not the engine used.

Hyundai has been developed for more than 140 years, and a car is equipped with only one engine. And today made pure electric drive the car, the motor can be equipped with the number of? One is necessary, up to every wheel with a drive motor.

Second, pure electric way basic classification

Engine layout by the different positions, can be divided into front, center, rear three categories. And then you can subdivide the front drive, front drive, the rear drive, rear drive and so on. If it is a drive motor, can also be divided into front, center, rear and so on. At present, the motor drive mode is further derived from a number of motor drive mode, so there is a centralized drive mode and distributed drive mode.

1) centralized drive and then subdivided into single motor and dual motor program two categories

A) Three modes of single motor drive

Figure 1 single motor drive three modes

B) Dual motor driven four modes

Figure 2 two motor-driven four modes

2) Distributed drive is divided into three kinds of wheel motor and wheel motor

A) rear wheels with two wheels;

B) Two wheels on the rear wheel motor

C) round wheel motor

Third, direct drive large-scale bus was respected the basic reasons for analysis

GB standard stipulates that the maximum speed of large buses is ≦ 79 km / h, the first-tier cities use the machine to remind the driver not to run more than ≦ 50 km / h, the bus company is currently operating at an average speed of 30 km up and down, the city is not allowed on the large bus City elevated road.

The basic meaning of the direct drive program is that it does not match the gearbox. The basic function of the gearbox, in the gearbox input to accept the motor input power, and in the gearbox output torque and speed between the change ratio of the switch.

The maximum speed of a large bus is ≦ 79 km / h has been lower, but the torque requirements are high. This situation is bound to require large torque and low speed motor, obviously using multi-gear gearbox, it is somewhat rich. Plus the current domestic 3 files below the gearbox, technical maturity from the bus company's request, there is a distance.

The author's point of view is that large-scale bus was under the direct drive program is also a temporary measure. But after a long period of practice has proved that the use of direct drive program is not the best, but still in line with the actual conditions of China's bus, follow-up to improve the basic idea is,

A) improve the efficiency of high speed on the basis of large torque motors;

B) on the basis of large torque motor, with the performance of stable AMT;

C) When the motor is arranged in the middle position, if the AMT performance is unstable, it is not appropriate.

Fourth, the current commuter pure electric bus with AMT is appropriate

AMT Chinese meaning automatic clutch gearbox, popular understanding, in the manual transmission on the basis of a set of computer-controlled system, you can achieve automatic shift. The actual product has a technical requirement, if directly in the traditional manual gearbox, load a computer-controlled system to achieve automatic shift, the effect is not ideal.

The development of a set of suitable for pure electric buses supporting the AMT difficult, not in the computer control system, and in the implementation of components and manual gearbox with the mechanical interface.

Has not been there, the traditional engine does not deserve the gearbox of the car. China's car in the traditional car more than foreign brands of cars, we discuss more of the cutting-edge technology in the engine technology abroad. People in the industry know that the gearbox along the technology is also abroad. China has developed a pure electric vehicle, the bus has been a direct drive program of electric buses. If the direct drive program can be optimized, the direct drive program appears in other categories of electric vehicles is also possible.

The basic reason for the commuter pure electric bus with AMT is:

A) With AMT, power performance is better, lower power consumption, especially in high-speed operation, power consumption is more obvious;

B) with AMT, the system weight is lower, the maximum weight loss of 40%;

C) requirements for motor and motor controllers can be reduced more;

D) AMT may have power interruption in the shift, but the commuter pure electric bus shift is not frequent.

Suzhou Green Control, Nanjing Bo more in the AMT research and development, the market pioneered a lot of work done on the Qijiang gear in the AMT to 3-4 gearbox, put a lot of manpower, financial research and development of new products, Made progress, it should be said to be remarkable, can be point.

In summary, the current commuter pure electric bus with AMT in power consumption, power, cost and other aspects of a certain advantage, but the premise is AMT performance must be stable.

V. Analysis of the advantages and disadvantages of the direct drive without conventional shaft

The previously mentioned direct drive program, or a drive shaft. At present in the special logistics vehicles have been no conventional shaft of the direct drive program, that is, the motor is concentrated on the drive axle, cancel the drive shaft and the traditional bevel gear or spiral bevel gear main reducer. Its intention is to improve the transmission efficiency, power is strong, the effect of reducing power consumption, but also reduce the quality. The current difficulty is that the unsprung mass is heavy, resulting in poor comfort of the vehicle. The author's point of view, this program if you want to use the bus, the reason is not very full.

Sixth, the advantages and disadvantages of centralized dual motor drive program analysis

On the dual motor drive program, the author has not understood the basic intention of its designers. Is to make up for the lack of single motor, better energy saving? Dual motor drive scheme for a high speed motor and the other is a low speed motor. Between each other must be a combination of work. But there must be two motor controllers, the vehicle controller to coordinate the two motor controllers. This program for outsiders, it is more and more complex, the cost is also increasingly high. Beijing precision motor in trying this program, how to market reaction? To be verified.

Seven, wheel (wheel) motor program or bright spot, far away from the hot spots

Engine cars can not be separated from the clutch, gearbox, pure electric bus to take a direct drive is not allowed to do so. No traditional axis of the direct drive program for the bus, how to overcome the heavy quality of non-sprint is difficult, but also do not see its feasibility.

What is the basic intention of developing a wheel (hub) motor solution?

A) is easy for energy recovery? How much energy can be recovered;

B) is it easy to move the car sideways? Horizontal movement to customers in terms of how much value added;

C) reduce the floor height of the bus bus? The current height of the bus floor can also drop much, how much value added to the customer.

(1) wheel edge drive program advantages and disadvantages analysis

Assuming that the wheel motor performance is stable, the following only from the car drive technology to be analyzed. The wheels are equipped with a motor on both sides of the vehicle, driving the wheel separately, which eliminates the main reducer and differential, with the intention of less power consumption. There are currently two problems:

A) high-speed turning and road surface bumps on the differential control, electronic differential performance can not be compared with the performance of mechanical differential. This is a serious technical security problem.

B) high non-reed mass, resulting in a serious decline in passenger comfort. Such products push the market, the customer will buy it?

(2) Analysis of Advantages and Disadvantages of Wheel Motor

Assuming that the wheel motor performance is stable, the following is only from the car drive technology to be analyzed.

The hub motor is mounted inside the hub. Eliminating the drive shaft, reducer, etc., its efficiency may be higher, more energy efficient. But a serious look at the wheel drive program, the wheel motor program has. There is a security risk, that is, the motor controller integrated into the wheel motor, how to protect the reliability?

8, research conclusions

The current focus on the main drive, the future is distributed driven. At present, the basic technical route of the pure electric bus product developed by the bus company is the single motor + AMT (gearbox (2-3) + drive shaft + traditional bridge. If it is product development (or the latter is Parts verification), it is another matter.