When the people of Xiang&Tan Motor Factory were shocked by Lin Zheng's wealth, Lin Zheng was also depressed: he needed to have a detailed understanding of electric drive technology.

If you want to know about electric drive technology, you have to talk to Andrey.

"The exhibition of electric drive technology has actually been many years, the earliest urban rail tram, which is an early electric drive technology, but if you talk about the early electric drive technology of mining vehicles, it has to be traced back to the early stage of World War II, well, it was in 1938 when Italy was building the Valtrina hydropower station, the first electric truck was used to transport concrete, when there were 16 three-axle trucks and 4 two-axle tractors on the construction site, but the capacity of the truck was there, but the power was still not good, Taking into account the high torque output characteristics of the electric motors, the construction party converted the 2o trucks to electric drives: a long collector pole was installed on the top of the cab and built on a 65o volt DC overhead line network to provide power to the vehicles, with a total length of 8o kilometers. In essence, it is similar to the current urban tram and trolleybus, which is the earliest mining truck, of course, more precisely, it should be said that it is the prototype of the electric drive mining car. ”

In 1938? This time is really a bit unexpected for Lin Zheng: Is it so early?

"But the prototype of the real electric drive mine car that is widely recognized by everyone appeared in the United States in 1939, when the American International Salt Company was building an underground mine in Michigan, and the mine could not be entered due to overhead wires. They converted a batch of 2O short tons of ukulele trucks into electrically powered trucks with batteries and DC motors mounted directly on the differentials. After more than 20 years of successful use, the trucks are truly electrically driven trucks – they are finally free from overhead cables and can drive freely. ”

"Understood," Lin Zheng, who had not had time to talk to Andre about this issue, finally nodded in understanding, but with Andre's explanation, a new question came again, "Andre." I want to know, since the electric drive technology has been used in mining vehicles for so long, why has passenger cars, commercial vehicles, and commercial buses not been used with electric drives? ”

Yes. This question is also one of the most puzzled questions since he knew that mining vehicles have long been using electric drive technology: since mining vehicles have been using electric drive technology for so long, why have passenger cars, commercial vehicles and commercial buses not used electricity as driving power?

Well, trams and trolleybuses powered by overhead cables don't count.

"This relates to another issue of the electric motor, the power density of the electric motor."

"Power density?" Lin Zheng was surprised: I have watched a lot of things during this time.

"Hmm. It is also called the power-to-weight ratio. It is a motor, and the maximum power of each kilogram of its own weight can be produced. Andre explained to Lin Zheng, "This is a relatively remote professional vocabulary in electrical engineering. ”

Understood, Lin Zheng nodded again and again, for example, a motor weighs 2o kg and has a power of 2.5 kilowatts, so the power-to-weight ratio. The comprehensive density of the lake is O.125. This power density of an electric motor is a certain range dù on and the liter power of an internal combustion engine is a meaning, the electric motor is the maximum amount of power per kilogram weight that can be output. The liter power of an internal combustion engine is the maximum amount of power that can be output per liter of displacement...... Of course, the internal combustion engine also involves a question of self-weight of motivation. However, it is not the main factor that affects the power output, and the biggest factor affecting the power of the internal combustion engine is the exhaust volume.

He was suddenly relieved: no wonder he didn't see this thing, for example, those car enthusiasts who talk about cars like a few treasures, and memorize the various cars made by various automobile giants, you ask him what is the power of the car motor, these guys are also at a loss: power liter? What is this?

In the same way, as a quasi-layman, and not a major in electrical engineering, my buddy has not heard of this electrical professional vocabulary with relatively remote and unpopular power density, and I can fully understand it.

Andre is a good subordinate, seeing that his boss nodded, he continued, "The efficiency of the motor is very high, even the efficiency of the most ordinary AC excitation motor can generally achieve more than 85%, and the efficiency of the DC motor can even achieve 92% to 95%, compared with the gasoline engine with only 36% of the theoretical upper limit of efficiency, this is the innate advantage of the motor, and the internal combustion engine such as gasoline engine and diesel engine cannot be compared in any case." ”

"What is the power density of a mining vehicle?"

"It's probably O.18 to O.25, mining cars pay more attention to torque, not so much to power, and the distribution ratio between power and torque in the early motors is very exaggerated," Speaking of which, Andre has to give an example, "Siemens is developing an electric motor for commercial buses, with a maximum power of only 16o kilowatts, The power density is only O.3, but the maximum torque is 25oo Nm, which is greater than the torque of many diesel engines with a power of 3oo kilowatts, and the ratio between power and torque is more than 1:15.6, and the maximum ratio between diesel engine power and torque is only 1:6. ”

What is the power-to-weight ratio of O.18 to O.25? Understood, Lin Zheng finally understood what the problem was: the mine body is wide and fat, the dead weight is often tens of hundreds of tons, and its use time is almost 7 * 24 hours in addition to maintenance, although it cannot be said that it does not care about the cost, but durability, reliability and economy are the first considerations they put in the first place, the power match of "diesel engine-motor-motor" greatly highlights the large torque output characteristics of the motor, which just meets their use requirements.

The weight of a motor of a mining car is calculated in tons, and the weight of the motor is a little more or less, but the passenger car is not like that, and the overall weight is only more than a ton...... In particular, the requirements for the power density of the motor are much more demanding than the mining car, the weight of the motor of a mining vehicle increases by one ton or two tons, but the motor used in a passenger car, the weight increases by 2oo kilograms?

It is no wonder that electric drive technology has been used in mining vehicles for so long, but it will take several years for ordinary civilian passenger cars to begin to appear gradually.

Knowing what the problem is, Lin Zheng is much more down-to-earth, yes, he is not afraid of complicated roads, he is afraid that he will go the wrong way, since he has not taken the wrong road, then there is no problem.

After pondering for a while, Lin Zheng spoke, "So, if you want to achieve electric drive in a passenger car, this power-to-weight ratio should be at least more than 2?" ”

"This is the least, if you can achieve a power-to-weight ratio of more than 3, it would be the best, under the premise that the cost is acceptable, it can reach 4, then the ideal can not be more ideal," Andre is worthy of being engaged in motors all his life, he has understood what the boss meant, and immediately nodded when he heard this, "And the output ratio of power and torque can not be too exaggerated, I think it is a relatively safe situation to fluctuate up and down in the ratio of 1:2, but this requires the rotation of the motor to reach a fairly high range dù, In the case of DC permanent magnet motors, the rotation must be more than 11ooo, even if it is an AC excitation motor, the rotation must be more than 85oo revolution. ”

1:2？ That is, the output power of 1oo kilowatts roughly requires 2oo newtons. meters of torque? Well, compared with the exaggerated ratio of power and torque output of more than 1:1o of the mining car motor that I learned some time ago, this ratio is really suitable for passenger cars.

In order to adapt to the requirements of the use of automobiles, the output ratio of power to torque of gasoline motors is more exaggerated, almost 1:1...... Although the focus of each family's consideration is different, and the ratio fluctuates slightly, it only fluctuates between 1:1 and 1:1.5.

"Since that's the case......"

Lin Zheng raised his head and looked at Andre, "Andre, the company is ready to launch the electric drive technology of passenger cars, well, the first to launch is the 'gasoline-electric' hybrid drive technology, which is similar to the theory of the concept car called 'Prius' that Toyota exhibited at the Tokyo Motor Show, but the slight difference is that what we want to do is more advanced, and it can be directly charged by external mains, what do you think?" ”

"Toyota Prius?" Andre frowned and thought for a long time, but finally didn't remember what this Toyota Prius was, so he had to smile wryly and said, "Boss, I'm sorry, what kind of hybrid drive concept is this Toyota Prius?" ”

It's understandable that Andrei doesn't know about the Prius, although the Prius was first unveiled at the Tokyo Motor Show in January 93, but at that time Belarus was in dire straits, who would have the time to care about such a hybrid car thousands of miles away? …… What kind of car is not a car, the main thing is to let me fill my stomach first.

Although Andrei had just gone to the United States at that time, he was thinking about gaining a foothold in the United States when he first went to the United States, so naturally it was impossible to pay attention to this little thing...... His profession and work are all mining trucks with a load capacity of hundreds of tons, Prius? It's basically out of line with his work.

Don't say Andre, even if it's Lin Zheng, isn't it that after collecting relevant information about Toyota's hybrid vehicles, he collected some information about Toyota's "Prius" hybrid car that was unveiled for the first time at the Tokyo Motor Show in 93? (To be continued......)

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