Starting late, the foundation is thin, and independent brand fuel vehicles have been lacking hard-core works in the three major fields, especially in the field of transmissions, the global market shipments & influence can be ranked with high-quality products, which are also a few in Germany ZF, Japan Aisin Seiki, South Korea's Paivotai, the United States BorgWarner and so on.
However, in today's era of electrification, the major autonomous car companies seem to have found a new way to "overtake in curves" in the field of transmission: since the transmission is not good, can the car not be a transmission? The answer is, yes!
Represented by the BYD DM-i series, a variety of domestic hybrid vehicles have sprung up in the past year, and they all have a common feature: on the basis of the hybrid special engine, the flexible control of vehicle power & speed is realized directly through the electromechanical coupling and power shunting of the engine and motor. This hybrid design idea and scheme not only has a lower fuel consumption compared with pure fuel vehicles, but also directly crosses the threshold of traditional fuel vehicle transmissions, which is of great significance to the future development of domestic vehicles.
Engine, why equipped with a transmission?
We all know that fuel vehicles need transmissions, but most people may not have thought about why this thing is needed, can't you directly control the engine speed through the throttle, and then control the speed?
Internal combustion engine: Stable output & high efficiency can only be achieved at relatively narrow speeds
The truth is no! Because the output power of the internal combustion engine is related to the speed, load, and fuel injection, its efficient operating conditions are very narrow for the actual car environment of the family car, which is 1500-3000rpm. At this time, the engine needs the cooperation of the transmission, and the torque amplification (low gear) and speed amplification (overspeed) functions are realized with different speed ratios in different environments. If there is no transmission directly connected to the semi-shaft through the reducer, the vehicle can only run within a very narrow working range, and the starting, acceleration, climbing and other working conditions cannot be fully taken care of, and the car cannot run at all.
It is balanced by gear speed ratio to balance speed and torque
When taking the manual transmission driver's license, everyone should have encountered poor oil separation or incorrect timing of the upshift, resulting in the car stalling, the core reason is that the engine speed /power/injection volume is not ready to cope with the high load, so it is directly stopped. The automatic car computer will automatically control the clutch, giving priority to the normal operation of the engine, so that it will not turn off.
Motor driven, why don't you need a transmission?
So the question is, why do pure electric cars not need transmissions? The reason is also very simple: because at zero load, the output power (speed/torque) of the motor can be completely controlled linearly by the input power given by the battery, and the conversion of speed & torque can be more freely controlled in the full speed range.
Electric drive: Power output is related to low speed
How does the fuel car start? The brakes are pressed, ignited, the engine speed is 600-700rpm, and the car starts successfully. How to start a pure electric vehicle? There is no need to step on the brakes, press a key to start, in principle, the drive motor is already on standby. At this time, how many "electric doors" you step on, the battery will give the motor the corresponding power input, as long as you reason, even zero speed can achieve the maximum power output on the wheel. On pure fuel vehicles, the owner needs to increase the speed through throttle control and a large amount of intake fuel injection to obtain greater power output.
Volkswagen ID.5: MEB electric drive platform, single motor rear drive
To put it bluntly, the motor drive has no concept of idle speed, "electric gate" is equal to power, not only because there is no clutch transmission work to make the power response more direct, more importantly, its output power and speed are low correlation (not zero correlation), but directly controlled by the "electric gate".
Porsche Taycan: Two-stage gear shifting, amplified torque
Of course, the function of the transmission as a torque or speed amplifier is actual, pure electric cars can naturally also be equipped with two to three levels of transmission mechanism, so that you can get a more powerful torque output by regulating the speed (small gear with large gear) when floor oil, and at the same time, when cruising at high speed, you can also further optimize the motor speed by speed regulation (large gear with small gear) to improve efficiency. Therefore, to be strict, pure electric cars are not "no transmission", but "can have no transmission".
How does a hybrid control power & speed?
So the question is, the hybrid also has an engine, less transmission, can the engine still work properly? Won't there be a stall problem? Not really!
On the left, the speedometer; on the right, the power input/output meter
Those who have learned a little about hybrids know that including Toyota Corolla Twin Engine, Honda Accord Rui Hybrid, BYD Qin PLUS DM-i, the dashboard of these cars only has a speedometer, no tachometer. Because the motor replaces the engine + transmission, the auxiliary power output and speed control work are done, and the engine is always in the highest thermal efficiency working range of about 2500rpm, showing the speed for the owner is meaningless.
At this time, if it is cruising, downhill or braking conditions, the engine finds that the power output brought by 2500rpm is excessive, and a part of the power will be diverted to the generator to charge the battery, that is, energy recovery; and if it is the starting floor oil, uphill or high-speed acceleration conditions, the engine finds that the power output of 2500rpm is not enough, and the engine will not actively pull up the speed, but let the drive motor "absorb" the electrical energy stored by the battery and provide additional power output. In this regard, Toyota Motor gave this idea a very vivid name "peak cutting and filling valley".
As a combination of internal combustion engine drive and motor drive, the hybrid vehicle is in a sense a combination of the advantages of the two. The application of the engine allows the motor to have a continuous source of power (charging the battery), while the application of the motor allows the engine to get rid of the transmission and operate under more stable speed/load conditions throughout.
●Summary:
Since 2021, BYD DM-i, Great Wall Lemon DHT, Geely Thor Hi · X, Chery Kunpeng DHT, GAC Trumpchi 2.0TM + THS are listed /released, although there are certain differences in engine electrification and dual motor layout, but they all have one thing in common: there is no independent transmission! This allows domestic fuel vehicles to solve the pain points that have been in the field of transmissions, and domestic cars finally do not need good transmissions, and can also make a well-known hard-core good car.