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Honda electronically controlled clutches


Perhaps the main difference between modern motorcycles and those we drove 20 years ago is not LED light, not touch-sensitive dashboards, and not even on-board assistants, but electronic gas, thanks to which these very assistants have appeared in large numbers and are actively developing.

The era of onboard assistants

The first production motorcycle with e-throttle was the 2006 Yamaha YZF-R6, which eliminated the direct mechanical link between the throttle stick and throttle valves, replacing it with a simulated servo-based one. The main advantage of that system was a surprisingly accurate imitation of the feel of the throttle: not knowing that it is electronic, you cannot imagine this in your life. Then similar technologies appeared in the arsenal of almost every manufacturer, and they became so widespread that it is now difficult to find a new motorcycle with a conventional cable choke drive.

At first, e-gas became a boon for designers who were in a difficult situation due to environmental requirements. It made it possible to implement the most accurate fuel maps, when, for each angle of opening of the throttle grip, it is possible to calculate in advance the amount of air entering the engine per unit of time, and to it – the amount of gasoline, the duration of its injection, the ignition moment and some other aspects of the engine operation, and thus create a motor with smooth, linear throttle response and green exhaust, even if actual physical throttle bodies are not fully synchronized with the rider’s hand movements. Thus, the traction characteristics of the motorcycles were artificially extended without any loss in peak power and traction, simply by more accurately distributing the torque shelf over the travel range of the right grip.

And soon manufacturers really appreciated the possibilities of electronic throttle control – the era of on-board assistants began. The first, of course, was traction control: if earlier, in order to prevent or stop the rear wheel stall, it was necessary to create a misfire or interrupt the fuel supply, now the ECU assisting the rider only needs to cover the throttles a little and thereby smoothly reduce the traction. And with the advent of inertia measuring devices on motorcycles, wheelie control, launch control and cornering stability control have joined traction control – that is, all those algorithms that require no engine interruption for reliable and safe operation (albeit for a short time), and surgically accurate dosing of traction. But what’s next? Did the development of motorcycles stop there?

Electronic clutch

Honda believes it has found the next motorcycle component that needs some work. This time it’s about the clutch, and Honda has already filed several patent applications for an electronically controlled clutch.

Honda’s idea is a hydraulic clutch operated by a lever on the steering wheel. However, unlike existing designs, there is no direct hydraulic line between the arm and the slave cylinder. The position of the clutch lever is monitored by an electronic sensor, and based on this data, the control unit commands the hydraulic controller to change the pressure in the line of the clutch slave cylinder. In addition, the control unit monitors the position of the throttle stick, the gear engaged, the engine speed and the movement of the gear lever.

Unlike a conventional clutch, which in its “usual” state connects the engine and transmission, and disconnects them only when the lever is depressed, the Honda electronically controlled clutch is disconnected by default. When the system lever is released, the electric motor of the hydraulic controller moves the piston of the master cylinder, builds up pressure in the slave cylinder and compresses the clutch discs, so that the thrust from the engine is transferred to the gearbox. This is done for safety reasons: in the event of a complete failure of the system, traction will simply cease to flow to the transmission.

Use cases

Additional data monitored by the electronic clutch control unit allows for a wide variety of functionalities: in some modes, the clutch will work fully automatically, simulating, for example, the operation of a quickshifter, only instead of interrupting the ignition or adding gas, the load from the gearbox shaft will be removed by disengaging the clutch, and the synchronization of the engine and wheel speed will occur in the most natural way, without any jerks at all. Here, additional options for launch control, wheelie control, traction control are possible – to the arsenal of traction controls, such as throttle valves, ignition and fuel delivery, the most efficient clutch will also be added.

Of course, Honda has made sure the clutch lever is squeezed out with a familiar feel, even if it’s completely digital. The company’s patent describes “reactive force generating device”, working in tandem with the lever and giving feedback despite the absence of a direct connection between the lever and the position of the discs in the clutch basket.

When riding with the lever released, the motorcycle will monitor and hold the clutch pressure. so that the grip always remains in “working” condition by transmitting traction. In addition, the system will be able to detect the start of movement or braking and smoothly “let off” or “squeeze” clutch.

So the new idea of ​​Honda will allow at least to forget about the engine stalled due to inept work with the lever.

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