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An electronic clutch allowing Start-Stop coasting


Traffic congestion is bad enough at the best of times, but doubly irksome without automatic transmission. The reason is the constant switching between clutch, gas pedal, and brake. In stop-and-go traffic, the Bosch eClutch allows drivers using manual transmission to use first gear without using the clutch. They can simply use the brake and gas pedal, just like in an automatic transmission, without accidentally stalling the engine. This electronically controlled clutch closes the gap between automatic and manual transmission. In addition, the eClutch makes the coasting function possible, which saves fuel. Independently of the driver, the clutch decouples the engine from the transmission if the driver is no longer accelerating. The engine then stops. The result is a real fuel saving of 10 percent on average.

Bosch electronic clutch

In terms of price, the eClutch costs significantly less than a conventional automatic transmission, and is thus an attractive alternative in the compact car segment, where price competition is tough. Unlike a full-blown automatic transmission, the e-Clutch automates the clutch only, not the transmission. The clutch pedal transmits an electric signal to an actuator, which decouples the clutch.

The principle behind the start-stop coasting function is simple. The Bosch system detects the driver’s easing of pressure on the gas pedal, decouples the engine from the transmission, and thus prevents the engine from consuming fuel. Drivers can already manually simulate this effect by disengaging the clutch on a downhill stretch. In the future, the system will automatically assume this function, while stopping the engine at the same time. This is technically sophisticated, but worthwhile, leading to a 10 percent reduction in fuel consumption.


Helping prevent jerky gear shifts

As well as the stop-and-go function and the possibility of saving fuel, the eClutch offers a number of other functions. For example, it can be used to support gear shifts, making them smoother. A special sensor detects the start of a gear shift and adjusts engine speed.

And if the powertrain is electrified, the electronically controlled clutch means that a combination of hybrid powertrain and manual transmission is now possible for the first time. Up to now, it has only been possible to combine a hybrid powertrain with an automatic transmission, since it is not possible to coordinate a combustion engine and an electrical powertrain using a merely manual transmission. In this respect, the eClutch offers two advantages: manual transmission is still possible in hybrid vehicles, and the price of entry-level hybrids can be reduced, since a fully automatic transmission is no longer necessary.

Source: Bosch
Romain’s opinion:

This is a smart solution between the robotized gearbox and the manual gearbox. Then the quality and robustness of the component must be 100% verified. Do you think Bosch used ISO 26262 functional safety standard to assess safety of the system?

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