Behind each silky acceleration was a mechanical symphony of milliseconds of precision. When you press down on the accelerator and feel the gears turning silently without any jerking, you might not think the gearbox is experiencing the triple magic of gear meshing, hydraulic surging and electronic calculation. What secrets are hidden in this maze of steel?
The first trick: Gears "tacit speed coordination
The nature of gearshift is to change the transmission ratio-allowing a combination of gears of different sizes to appear, which determines the speed at which how fast the output shaft rotates and the torque produced. But gears can't be replaced at will. If two gears mesh at different speeds, forcing a bite into them makes a metallic clang.
The solution to manual transmission is "synchronicity." This seemingly inconspicuous conical friction ring, through the friction of shifting gears, powerfully smooths the speed gap between the gears, allowing them to "shake hands" before completing meshing. The Volkswagen MQ200 manual transmission has a unique synchronous ring structure, and the gearbox shifts like a moving stream with strong suction. The AT gearbox is even more complex - it doesn 't require forced detachment or meshing of gears at all, relying instead on the alignment and combination of planetary gear sets. With the hydraulic system controlling the engagement and detachment of different clutches and brakes, the three components of the solar gear, planetary carrier and ring gear can be switched between six transmission ratios. The six-speed AT gearbox contains three or four sets of planetary gears that act like mechanical Rubik's Cubes, completing silent gear transitions between combinations.
Second Magic: The "Flexible Transmission" of liquids
If gears are the driving force of hard bridges and horses, hydraulic torque converters are masters of using softness to overcome hardness in Tai Chi. AT Gearbox eliminated the manual clutch and replaced it with a hydraulic torque converter made up of pump wheels, turbine and guide wheels. The engine drives the pump wheel to rotate, drains hydraulic fluid, the hydraulic fluid shocks the turbine to transmit power. This kind transmission method oil film isolation, naturally has the characteristics of cushioning and damping, can effectively isolate the vibration and impact of the engine.
Even better, when the gear shift is complete, the locking clutch inside the hydraulic torque converter completely locks the engine and gearbox together, making transmission much more efficient. When a gearshift is required, the clutch is locked out and the hydraulic torque converter becomes a "shock absorber pad" to absorb the shock of a sudden load change. The key to smoothness is the ability to switch between softness and rigidity.
Magic # 3: Electron Millisecond Prediction
Modern gearbox is no longer a mechanical device, but an electromechanical integrated system with an ``intelligent brain ''. Electronic control unit capture dozens of parameters, such as speed, engine speed and throttle opening, in real time, calculate optimal shift times in milliseconds, and then push the clutch and gear through a hydraulic system or electric actuator with precision.
The dual clutch transmission pushes the magic to the limit. It's basically a combination of two manual transmissions: the outer shaft for second, fourth and sixth gears, and the inner shaft for first, third and fifth gears. When you put it in first gear, second gear is ready. When shifting gears, the first clutch disengages and the second almost synchronized, the entire process taking less than 0.2 seconds, with almost zero power interruption. The electronic system can even pre-engage the second gear before the first is completely detached to allow seamless connection. The Volkswagen DQ381 wet dual clutch transmission features a separate cooling circuit and an electro-hydraulic control module for transmission efficiency up to 94%, with shift smoothness comparable to AT.
The CVT gearbox adopts two variable diameter cone wheels and high strength steel belt to realize continuous and stepless changes transmission ratio. The steel strip slides over cone wheel, almost imperceptibly, like walking on a smooth slope rather than up a flight of stairs.
From the frictional wisdom of the synchronizer, to the flexibility of hydraulic torque converters, to the precision of electronic system - the steady shifting of the transmission - it is a combination of mechanical precision, hydrodynamics and intelligent control. Every upshift you get the impression that "nothing happened" is the driving magic woven by countless engineers with gears that measure up to 0.01mm in accuracy and milliseconds in computation time.
