Steer-by-wire and shift-by-wire systems, which control steering and transmission through electronics instead of using mechanical and hydraulic means, have become increasingly popular in recent years, especially with the advent of software-defined vehicles (SDVs) and electric vehicles.
We may also soon add brake-by-wire technology to the list of electronics-driven vehicle functions if auto parts and tech supplier ZF convinces OEMs to adopt it. The company has unveiled a new purely electro-mechanical brake system that eliminates the need for brake fluid.
Instead of using the pressure of fluids in a hydraulic system, ZF's brake-by-wire system uses an electric motor to generate braking force at each wheel. Brake signals from the pedal to the electric motor are transmitted purely electrically, which is why it's called a 'dry brake-by-wire system.'
Developed for the global market at ZF's labs in China, the U.S., and Germany, the new brake system unveiled at the company's Next Generation Mobility Day in Shanghai targets software-defined vehicles (SDV) and electrically driven vehicles first and foremost.
ZF says this type of braking system has even more advantages on SDVs and EVs, opening up new freedom in design and development.
"Our purely electrically controlled braking system is a significant addition to our portfolio of networked chassis systems," said Dr. Holger Klein, CEO of ZF Group. "With such by-wire systems, we are opening the door to a new era of vehicle control."
So what are the advantages of using this system instead of a traditional one?
ZF claims the new brake-by-wire system enables shorter braking distances, better recovery of braking energy, and lower maintenance costs.
For example, during automatic emergency braking, the braking distance from 62 mph can be up to 29.5 feet shorter than with a conventional braking system. Another big advantage is that electric cars can recuperate braking energy more efficiently using a dry brake-by-wire system, and can therefore achieve 17 percent more range during regenerative braking.
"Compared with a conventional brake system (without recuperation), our system can extend the range up to 17% according to WLTP standard," a ZF spokeperson told InsideEVs.
Using such a braking system also results in almost zero residual drag torques that occur with conventional braking systems, on which there's minimal contact between the brake pads and the brake discs. The lower resistance during driving also leads to energy savings, increasing range.
There's also a reduced environmental impact of this technology as it produces fewer particulate emissions due to brake abrasion.
From a manufacturing standpoint, the advantages of using brake-by-wire without a hydraulic system include lower assembly and logistics costs, as there are fewer parts to put together. As for maintenance, the customer obviously no longer needs to change brake fluids, reducing the amount of servicing required.
For those of you who are worried that dispensing with the hydraulic system affects braking feel, ZF claims the driver feels no change with the dry brake-by-wire system compared to the hydraulic brake.
Interestingly, one of the photos accompanying the press release showcases a BYD Han electric sedan seemingly equipped with ZF's dry brake-by-wire system. ZF is one of BYD's main parts suppliers, but that doesn't necessarily mean that a production BYD car featuring the dry brake-by-wire system will enter production in the future.
"The BYD Han is one of our vehicles (of different OEMs) that we equipped with ZF dry brake-by-wire technology to demonstrate the abilities of our brake system – i.e. it's not a statement that BYD will equip its future series vehicles with our technology," ZF's spokesperson told us.
What do you think, will this technology make it to production and does it have the potential to render hydraulic braking systems obsolete?
Update Tuesday, November 14, 11:10 a.m.: This post has been updated with statements from a ZF spokesperson regarding the EV range increase offered by the dry brake-by-wire system and the BYD Han featured in the opening photo.