From a scientific point of view, "addition is easier than subtraction" is indeed logically supported. The logic recognized by most people is that addition is the simplest combination, and there is no need to compare the relationship between addend and addend. However, subtraction needs to compare the two groups of numbers of the minuend and subtree in a systematic dimension, which involves the relationship between the three groups of numbers of the minuend, subtree and difference. So subtraction is obviously difficult to add.
The same logic is not limited to mathematics. In actual production and life, especially in the field of technical application, "addition is easier than subtraction". For example, we can give an example of a new energy hybrid vehicle.
Two-gear DHT is used to insert and mix the second generation of Haval Dog.
When PHEV plug-in hybrid power was first developed, its basic definition was "short-distance electricity consumption in cities and oil consumption for long-distance travel", so its initial configuration was a hybrid power system with a single P2/ P3 motor in parallel outside the transmission system of internal combustion engine, relying on urban charging piles and batteries to meet the demand of pure electric/hybrid drive.
At this time, the hybrid system has only one motor and can only choose between power generation and discharge. It is easy to say that there is electricity. Once fed, the problem comes out, because the hybrid system and battery take up more weight, making the fuel consumption of the whole vehicle even higher than that of the traditional fuel vehicle, which is not worth the candle.
In order to solve this problem, clever engineers began to do addition for the first time.
If one motor can't work, then add another motor, one is responsible for power generation and the other is responsible for discharge, and then cooperate with an efficient series-parallel scheme that can meet the needs of various working conditions. For a while, hybrid power systems began to blossom everywhere, such as Toyota THS, Honda i-MMD, BYD DM-i, and Geely, Chery and Great Wall's own multi-gear DHT. Although the specific technical patents of the two are very different, they are essentially the product of addition, that is, the series-parallel hybrid configuration of two motors; And all the hardware is integrated on the front axle to realize the spatial optimal solution of the two drives.
Haval H6 interpolation using two-speed DHT
Compared with the traditional single-motor hybrid power, the dual-motor series-parallel hybrid power configuration obviously performs better in fuel consumption; But the only problem is that because there are more motors, the cost will be higher and the car will become more expensive.
That's not all. Does the fuel truck have a four-wheel drive? Of course, a hybrid car can't have only two-wheel drive, so how to do four-wheel drive on this two-wheel drive?
The second addition came again. In order to make the rear axle meet the hybrid demand, the hybrid four-wheel drive can be realized by adding the third motor P4 to drive the motor or directly adding the mechanical four-wheel drive shaft.
For example, Toyota's hybrid four-wheel drive E-Four, Honda's i-MMD Sharp hybrid four-wheel drive, BYD's four-wheel drive DM-i, DM-p, and even the four-wheel drive DHT-PHEV used by Great Wall Wei brand did the same.
The problem is that the four-wheel drive is indeed realized, but there is a high-power motor, a lot of accessories such as electric control, cables and cooling pipes, and it is still a mechanical transmission system, which increases the cost. Consumers think cars are more expensive and can't afford them.
Moka's four-wheel drive DHT-PHEV
Can you do subtraction? For example, it is still a two-wheel drive hybrid motor, but if you separate them, there is a front axle and a rear axle. As long as the battery is charging, can't it be a four-wheel drive?
It is feasible in theory, but technically it is definitely more difficult to do "subtraction" than "addition". Before Great Wall Motor released the "Hi4" intelligent four-wheel drive electric hybrid technology on March 10, no other manufacturer had set foot in this brand-new field.
Therefore, the Great Wall "Hi4" intelligent four-wheel drive electric hybrid technology is also the "first time in the world" for China people in the field of new energy hybrid technology.
Specifically, the idea of the Great Wall is actually very simple. Still based on the familiar two-speed DHT series-parallel deep hybrid configuration. There is no need to increase the cost. Just remove the traditional TM drive motor of the front axle at P3 position and put it at P4 position of the rear axle. At this point, the rear axle will have power and four-wheel drive will be available.
At the same time, this system is essentially a deep hybrid of two motors in series and parallel, with no new increase in weight and low fuel consumption.
The Great Wall engineering team also made an additional question, which not only did not increase the cost, but also reduced the cost. By the way, the clutch of the second gear DHT was replaced by a smoother and cheaper 2AT.
Great Wall Motor brand-new Hi4 hybrid engine+transmission
This is the slogan shouted by the Great Wall at the press conference, "The experience of four-wheel drive, the price of two-wheel drive; The performance of four-wheel drive and the energy consumption of two-wheel drive. "
Of course, Hi4' s "subtraction" logic is technically flawed. At the beginning, we said that a motor can only choose one of the two main tasks of power generation and discharge driving, and to meet the demand of series-parallel deep mixing, it needs double motors to ensure the bottom.
After Hi4 moved the TM drive motor at P3 position from the front axle dual motors of the rear axle to P4 position, there was only one GM motor at the front axle, which was mainly responsible for power generation. What about the electric drive of the front axle?
Great Wall Motor brand-new Hi4 rear drive module assembly
At this time, it embodies the Great Wall, the "learning tyrant" who does subtraction. Great Wall's scheme is to put the general motor of the former second gear DHT at the position of P 1 on the front axle, and optimize the layout at the position of P2, which not only retains the power generation capacity, but also has the function of driving the front axle. Therefore, Hi4 can achieve 100% pure electric four-wheel drive with sufficient power, or when the power is sufficient, not only the front and rear double motors, but also the engine and motor can exert power on the front axle to realize three-machine four-wheel drive, and the performance is cracked.
However, the cost of moving the general motor from P 1 position to P2 position is that the power generation capacity will be relatively weakened; This leads to another new BUG. When the power is sufficient, Hi4 is very strong. If the power is insufficient, it is a problem to maintain the four-wheel drive.
In order to make up for the power generation problem under the feed condition, Great Wall has also prepared a successor, that is, the engine has two direct-drive gears. According to the official information provided by the Great Wall, through the optimization of the transmission ratio of two direct-drive gears, the Hi4 can be directly driven by the engine with a minimum speed of 20km/h.. At this time, even if the battery pack is fully charged, the power of the front axle is provided by the engine, and the excess power can be converted into electric energy for the driving motor of the rear axle, that is, as long as the vehicle speed reaches the threshold of 20 kilometers per hour, even if the battery pack.
Haval Xiaolong MAX
Therefore, after a series of technical optimization, the only problem of Hi4 is the four-wheel drive maintenance when the speed is less than 20 kilometers per hour under the condition of replenishment. Theoretically, if the power and speed are insufficient, Hi4 can only maintain the two-drive mode of single front drive or single rear drive at this time, depending on the working mode.
As far as the current structure is concerned, this problem is indeed unsolvable. However, in essence, because PHEV has the ability to maintain power, with the help of electronic control software algorithm, excess power generation during driving, in-situ idle power generation and kinetic energy recovery ability, Hi4 can actually maintain power at a higher position in advance according to the owner's demand, which can avoid the embarrassment of changing four-wheel drive to two-wheel drive due to insufficient power.
So finally, to sum up, Great Wall has created a historic four-wheel drive configuration with two motors in series and parallel at the front and rear axles through "subtraction" at the system level, which not only points out a new way for the development of human hybrid technology, but also provides the technical feasibility of the goal of "four-wheel drive experience and two-wheel drive price" for a large number of new models, and provides hard support for many brands of Great Wall Motor to gain greater competitiveness in the automobile market.
In addition, compared with the mainstream traditional dual-motor hybrid technology, the new Hi4 has a more perfect 50:50 axle load distribution because it moves the motor with large mass and large space from the front axle to the rear axle, and has achieved a complete transcendence over the traditional automobile in terms of comprehensive strength such as safe operation and road trafficability, and can bring consumers a "more economical, farther and safer" driving experience.
This article comes from Qi Pai, the author of Good Che Yi, and the copyright belongs to the author. Please contact the author for any form of reprint. The content only represents the author's point of view and has nothing to do with the car reform.