The Alfa Romeo Giulia sports saloon hasn’t just been long-awaited by fans of the Italian company. Its brake by wire system, developed by Continental, is important for the future of braking on road cars. Here Nino Romano, vice president, research and development for Continental’s chassis and safety division, explains why.
“Brake by wire, where the physical link between the brake pedal and system is replaced by an electrical connection, has been used on cars for more than a decade. But the complexity of these systems meant they were expensive and made it difficult for the car manufacturers to reach the budget and price targets for the vehicles. Continental’s Mk C1 that features on the Alfa Romeo Giulia is a breakthrough because it fits within the business case for the car.
“With a traditional braking system, you have the vacuum pump, an actuation unit and the electronic systems such as the ESP and ABS. But with Mk C1 we’ve integrated these three usually separate systems into one. We’ve also removed the physical link between the driver and braking system. The result is a saving of 3kg which is a real help for car manufacturers where every gram counts in the battle to cut exhaust emissions.
“The safety benefits are also tangible. The booster within Mk C1 is much bigger than in a conventional braking system because it has to replicate pedal pressure from the driver too. Where a standard system would be able to increase the brake pressure from zero to locking in 300 milliseconds, the Mk C1 can do it in 100 milliseconds, an improvement of 300 per cent.
“In a situation where every millisecond can be the difference between life and death that is vitally important. In combination with our latest third generation ABS, Mk C1 can cut the stopping distance from 62mph to zero by up to 1 metre.
“The driver sees other benefits. For a start because there is no physical link to the braking system, you can reduce vibration through the brake pedal and limit any noise coming into the cabin from the brakes. It also gives the driver choices.
“Think about a regular car. The ratio of pedal force to deceleration is fixed throughout the life of the vehicle. You might be able to alter the various characteristics of the vehicle such as the accelerator and damping from sporty to comfort and so on. But you could never influence the ratio of brake pedal travel to deceleration. Now you can.
“You can give the braking system much more aggressive characteristics in race mode. You can make the pedal much stiffer so maybe you move the pedal a couple of millimetres and you go from braking deceleration down to locked wheel. It’s the freedom you have with decoupled systems.
“Ironically, it was difficult initially to convince car manufacturers that there wouldn’t be any negative characteristics to having a ‘synthetic’ pedal. After all, customers have certain expectations that the car makers have to meet. One of their doubts was that a brake by wire system on a sporty car could match what the driver was expecting. I think we settled that in the best way possible when the Alfa Romeo Giulia beat the four-door lap record around Germany’s Nurburgring race track. It demonstrated that the feeling is the same, if not better.
“But that wasn’t the biggest challenge. The hardest thing has been developing the brake by wire’s safety systems. When the master cylinder on a regular braking system has a leak or the booster isn’t performing correctly, the driver feels it through their leg. Now the system has to do that detection work so it is constantly checking itself and verifying that it’s working correctly. And if it does fail, there’s a lot of degradation between a fully functioning system and a loss of power – far more than on a conventional system. So in all respects, safety really is on a much higher level than existing braking systems.”