Delphi Corp. has developed what it describes as a revolutionary new technology that it believes will help solve many of the challenges currently faced by braking engineers. Based on a twin floating disc architecture with a single piston, the Delphi Maximum Torque Brake provides a high specific torque capability, with substantial improvements in thermal management that can lead to benefits in weight, packaging and NVH (Noise Vibration & Harshness / refinement).
“The traditional solution to coping with increasing vehicle weight and performance is to up-rate conventional braking systems, including larger discs (often forcing larger wheels) and advanced materials, but this is a costly solution that has a negative impact in many other areas of vehicle engineering,” explains Chris Baylis, director of engineering at Delphi’s Leamington innovation center. “Maximum Torque Brake solves these problems and is the first significant change in base braking technology since the first volume application of disc brakes more than 50 years ago.”
Maximum Torque Brake uses two discs floating on the outside diameter of the hub. A hydraulically actuated piston applies braking force via pads that operate on the outside and inside faces of each disc, providing four friction surfaces. The new technology can therefore provide up to 1.7 times the torque output of a conventional single disc system of the same effective diameter, or similar torque from a reduced diameter. Wear and serviceability are equivalent to today’s traditional product and the floating disc architecture eliminates problems with lateral run-out.
The twin disc design also provides four cooling surfaces, without the need for vanes or cooling channels, substantially reducing thermal stress on the brake and hub-mounted components.
Delphi says this improved thermal management provides engineers with many options for enhancing other aspects of the braking system. By greatly increasing opportunities to optimize the combination of disc size, pedal travel, booster size and friction material, Maximum Torque Brake allows the feel, cost and performance of the system to be precisely matched to market requirements.
Other benefits claimed for the system include reduced brake fade and, due to the reduced apply pressure, shorter stopping distances in the event of a vacuum failure — a homologation requirement that can be increasingly challenging to meet using conventional, highly-boosted systems. Delphi’s claims for the performance of the system are borne-out by testing to the independent AMS (Auto Motor und Sport) standards using a BMW X5 fitted with the system. In the 12-stop test, which is increasingly seen as a European standard, the vehicle demonstrated an exceptional “no fade” performance.
“Conventional brakes struggle to react against the torque of increasingly powerful engines, so stability programs have to be calibrated to shut the engine down early at the expense of refinement and driving pleasure,” explains Baylis. “Maximum Torque Brake will allow vehicle manufacturers to make the operation of these systems more transparent.”
“Maximum Torque Brake delivers an incredible range of benefits for both vehicle manufacturers and vehicle owners,” concludes Baylis. “With Maximum Torque Brake, we have a production-ready product that will allow Delphi’s customers to introduce a true 21st Century solution for vehicle braking.” Delphi says that discussions with vehicle manufacturers are progressing well and that the system could be in production by 2006.
For more braking system information, click here: A global market review for electronic braking systems – forecasts to 2006