Technology: automatic

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Technology: automatic
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Technology: automatic

Technology: automatic
Automatic transmission

Our everyday life is becoming more and more complex, and at the same time the urge to simplify is growing. Various concepts therefore want to automate gear changes on the motorcycle. Progress, yes the beginning of a new era? MOTORRAD examines the technology.

Jorg Schuller

07/03/2008

Motorized fun on two wheels is definitely one of the most demanding forms of transportation. The switch shop alone: ​​Newbies laboriously learn the complicated interplay of one foot and two hands, which, in addition to changing gears on the gear lever, means finely dosed connecting and disconnecting of the engine and drive train using the clutch lever, as well as setting the right speed and power on the throttle grip. A job that demands concentration even from experienced pilots, even if the processes take place almost automatically thanks to thinking routines firmly anchored in the memory. But why not automatically, as is the case with almost every car or scooter today?

Various concepts are preparing the replacement of traditional gear changes: The automatic gearshift, which has long been established in racing, comes as a sporty gearshift assistant in the BMW HP2 and enables you to shift up to full throttle without pulling the clutch. Yamaha’s YCC-S (Yamaha Chip Controlled Shifting, electronically controlled shifting) takes over the coordination of clutch and shifting ?? a system that weighs four kilograms and is very similar to the tip circuit in sporty cars, the FJR 1300 AS stands out due to the missing clutch lever.

Both systems would be just as conceivable in confident tourers as in extreme athletes, using chip-controlled helpers to simplify the operation of conventional clutches and transmissions. In the latter, link-guided shift forks move the gearwheels mounted on shafts in such a way that the shifting claws on the side of the wheels connect the gearwheels that match the respective gear. The interlocked frictional connection activates the appropriate pair of wheels on the input and output shaft and thus sets the required difference in speed. Aprilia and Honda are abandoning this principle, replacing the classic gearbox with real automatics. The Aprilia Mana, outwardly a normal motorcycle without a clutch lever, uses an electronically controlled V-belt transmission with a variable drive diameter and centrifugal clutch, similar to scooters: CVT (continuously variable transmission) was the name of the principle in the blessed DAF and many machine tools, it is also found in almost all of them Scooters.

No more gearshifts?

The Honda DN-01 even has a hydraulic torque converter: The compact HFT (Human Friendly Transmission) has a fixed swashplate and a swashplate with variable angle ?? both do not tumble, but only seem to do it because of their angular arrangement to the axis of rotation ?? hydraulic resistance and thus the speed between an encoder motor and the output shaft. The DN-01 also starts up using a centrifugal clutch and dispenses with a conventional shift lever, but can, like the Mana, be switched manually using a finger tip switch if desired.

Completely new territory? Already in the sixties and seventies, Jawa, Honda and Moto Guzzi were relying on more comfortable shifting. Too early, because the zeitgeist ridiculed the concepts as unsporting energy guzzlers. More pragmatically designed scooters started their triumphant advance early thanks to their simple handling: thanks to the centrifugal clutch and belt drive, getting on, accelerating and driving already worked on DKW’s blissful hobby scooter in 1954 and now represents, as CVT, probably the most widespread drive technology in the world, easy to use and robust. Automatic motorcycles, on the other hand, were forgotten? until now. As ever larger and more powerful scooters penetrate the territory of classic motorcycles, the time seems ripe for the next attempt. Whether shift assistant, YCC-S, CVT or hydraulic transmission: They all rely on driver relief in favor of increased attention and unadulterated enjoyment.

Is this where a development begins that has long been completed in the car? Where different automatic concepts meet the different demands on comfort or sportiness depending on the area of ​​application? A spread that could bear fruit in the diverse motorcycle world. By the way: Today nobody speaks of the fact that the automatic in the car is unsporting. So how long will it be before big tourers adjust the gentle force of their engines with the throttle grip? Or do super athletes make torque-optimized speed jumps using an automatically sequencing gearbox? Even if some readers are now protesting: We will only miss the switchboard as long as it works better or faster than the automatic. After that, many will enjoy the new simplicity ?? and enjoy carefree driving pleasure. What the four concepts presented on the following pages lay the foundation for.

Aprilia E-CVT

Aprilia, manufacturer of numerous scooters, transfers an electronically controlled CVT drive unit (see below) to the NA 850 Mana. Mana is currently finding many friends in the MOTORRAD endurance test: clutch, upshift, downshift ?? all of this is omitted if necessary. If you want, you can still change the gear to your liking and choose between manual or, as usual, positioned foot control. Driving like on a scooter, only much faster, with a good chassis, pleasant ergonomics ?? and silky smooth gear changes.

In the ?? Fully Automatic Mode ?? the electronics control the driving status and automatically switch up or down. Depending on the mode, it keeps the engine running at speed with optimal torque.

The driver can choose the engine and gearshift characteristics from three options: The “Sport” mode uses lively engine speeds, ensures crisp connections and fixed acceleration. ?? Touring ?? stands for low fuel consumption and pleasant everyday behavior. ?? Rain ?? eventually reduces the load thrusts on greasy roads.

In the “Sequential Mode” the driver decides for himself when to change gears, commands the gear change with the tap of a finger or foot. The translation changes a servo motor in seven gear steps ?? which feels like normal, very smooth shifting. If you forget to downshift, do the electronics? it couldn’t be easier. This convenient technology is likely to be found in other Aprilias in the future. It’s easy to get used to.

Honda HFT

Honda’s HFT is the name of a compact drive unit for hydraulic torque transmission and speed adjustment. HFT means? Human Friendly Transmission ?? a gear for philanthropists?

In any case, not only classic motorcyclists will buy the HFT-powered DN-01. Despite its 270 kilograms, it is very easy to drive, like a huge, extremely stable scooter. Your driver thinks he is in a science fiction film from the 70s? Attention guaranteed.

How does HFT work? The driver can choose between fully automatic and manual tapping of gear steps. A centrifugal clutch gently applies torque for starting. This drives a hydraulic motor on the primary or input side. So what? A swash plate fixed at an angle on the primary shaft presses against axially aligned, hydraulically acting master pistons through its rotary movement and transmits hydraulic pressure to analog slave pistons via intermediate oil. These in turn press on a second swash plate, this time at a variable angle to the secondary shaft. And now it happens: force of the ramp effect, the second swash plate evades the pressure of the pistons and is set into rotation, which in turn drives the firmly connected secondary shaft. Which finally transfers the torque derived here to the rear wheel ?? we drive while the oil pressure drops valve-controlled after bottom dead center and the oil on the low-pressure side to the ?? engine ?? flows back from where the cycle begins again.

The angle of the second swash plate determines the gear ratio and is set electronically to suit the forward thrust or manual gear selection: the more pronounced, the higher. At top speed, the disc is perpendicular to the secondary shaft, so it no longer wobbles ?? and is mechanically fixed to relieve the system. The driver does not notice any of this, but rather enjoys smooth starting and the same power transmission.

A new technique? Already in 1991 the Honda RC 250 MA won the Japanese Motocross Championship with HFT, certainly not a coffee trip. It is a question of tolerances and setting whether the time saved when switching outweighs the converter losses. Who knows? Maybe HFT by HRC will come soon.

Yamaha YCC-S

YCC-S proves how busy the coupling is. See the comparison of the FJR 1300 with and without an electronically controlled switch in MOTORRAD 18/2006.

A hydraulic pressure transducer, electronically controlled by the servomotor and pump, disengages and engages the normal friction disc clutch. As with the scooter, the vehicle starts up automatically by simply accelerating, and it is stopped by simply braking, with the clutch automatically disengaging. If shifting is to take place, the encoder disengages finely tuned and thus reduces the load in the transmission Prerequisite for loosening the shift claws and shifting the gear wheels to the next gear ratio.

When switching itself? triggered by the pilot at the push of a button or on the foot lever? sensor signals report the switching request to an electronically controlled stepper motor. This shifts the gear wheels using a conventional shift drum with shift forks. The clutch then automatically restores the frictional connection. The process is controlled by an electronic control unit.

Automatic switch

With the automatic gearshift no one shifts automatically, but at full throttle and without pulling the clutch up? which can save several tenths of the time to top speed with every acceleration.

The BMW HP2 Sport brings technology into everyday life. When shifting under full throttle, a pressure sensor reports the shift request to the engine management. For the moment of shifting, this takes back the pre-ignition and / or injection quantity and thus the interlocking pull on the shift claws: whoosh, damage-free gear change.

A work relief that, in addition to an optimized switching time, ensures a suitable traction connection ?? Thanks to the upstream mixture, you can continue gently and vigorously after the control is removed.

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