Clutch-by-wire helps saving fuel

September 22, 2015 // By Christoph Hammerschmidt
Powertrains with manual transmission are typically already more power-efficient than their automatic counterparts. Transmission manufacturer ZF now has introduced an “electrified” clutch that makes manual powertrains even more efficient.

Clutch-by-wire (CBW) is an electromechanical actuator system that for the first time allows to control the clutch independently of the driver’s left foot and from a mechanical connection between clutch and pedal. This enables car designers to implement fuel-saving features, in particular soaring.

Though manual transmissions are losing market share in favour of automatic ones, the absolute number of manual transmissions - and thus, clutches – is expected to climb for a long time. Against the background of the increasingly tough emission regulation this results in the necessity to continue to increase the overall fuel efficiency. ZF says it believes that such a potential lies in the clutch-by-wire. In this system, the clutch is operated by an electric motor under electronic control. According to the company, the soaring function alone – which requires an automatic transmission or an automated form of clutch control – could generate as much as 10 percent less fuel consumption. The CBM enables car designers for the first time to combine soaring with manual transmission.

Beyond fuel efficiency, the device is an enabler for several comfort functions. For instance it makes it possible to start driving without activating the clutch and to implement an anti-stall protection. Likewise, car designers can implement a crawling function which facilitates manoeuvring and parking through controlled slippage. In addition, designers can shape the characteristics of the clutch almost without limits. For instance, they could achieve a “sporty” clutch behaviour without requiring much force to kick the pedal.

The CBW has a powerful brushless DC motor that assumes actuates the clutch without the usual wire rope or hydraulics. The system comes with an integrated electronic control unit.

More information: www.zf.com