PORT PERRY, ON – In 1904, Frederick George Heath developed the first hydraulic brake system which used a handlebar lever to create pressure in a water-glycerin solution to actuate a piston. He patented this design (patent GB190403651A) for “Improvements in Hydraulic Brakes for Cycles and Motor Vehicles.” The concept of this design is the foundation for the hydraulic brake system in use today: a lever generates a force, a master cylinder converts the force into a pressure, tubular lines or hoses transfer the pressure to a caliper, one or more pistons at the caliper convert the pressure into a force and applies it to the friction surfaces.
Cars have changed considerably since their origin, evolving from open cabins and wooden wheels to the high-tech Electric Vehicles (EV). The difference is so vast that it’s hard to describe in words yet the newest of EVs still use brakes with the same hydraulic principles of actuation as brakes from 1904. It is time to reconsider this technology.
The brakes on a vehicle can take on a different role by changing the way they actuate and by digitizing them thereby eliminating all analogue subsystems (brake fluid). Enter the Remmen NEMB System: a Nonlinear Electro-Mechanical Brake system that makes use of a nonlinear transmission to effectively and efficiently convert electric energy into brake force.
How the NEMB Works
The NEMB System is comprised of one or more NEMB calipers. In an automotive application, each wheel of the vehicle has an NEMB caliper. Each caliper uses a Brushless Direct Current (BLDC) motor to drive Remmen’s proprietary nonlinear transmission and create clamping force. The system uses minimal energy and actuates in a fraction of the time of existing brake systems.
In a Smart Actuator configuration, each BLDC motor in a caliper has an integrated control module where Remmen’s intelligent brake control software, Irene, resides and creates a network of communication between each caliper. In a Remote Controller configuration, one Remote Controller installed on the vehicle is able to control two non-Smart NEMB Calipers. Irene is also installed on the Remote Controller. All calipers are connected to each other, and can communicate with each other, through CAN and through Irene, creating a transparent braking ecosystem.
The Vehicle Controls Module receives brake command inputs from the driver and other on-board systems. It then provides the brake command to the respective NEMB caliper based on the status of the vehicle.
Benefits
- Safety: Each wheel is a completely independent subsystem that can operate on its own or as part of a vehicle-wide system. This leads to a fully redundant system (mechanically and electrically) by design: there is no single point of failure that will result in the vehicle losing brakes; unlike hydraulic systems. As a final backup, each caliper can be mechanically actuator (if needed) by using a simple lever.
- Cost and Weight Savings: The estimated cost is lower due mainly to the elimination of hydraulic components that are typically needed to operate today’s electro-hydraulic brake systems. Also, due to the same reason, the NEMB System as a whole is lighter.
- Faster and More Precise: The proprietary transmission allows for actuation times that are faster, by far than hydraulic systems. However, in addition to faster actuation times, each caliper can be precisely controlled to actuate to a given torque. This leads to better dynamic system responses, shorter stopping distances, and overall better vehicular control.
- More Efficient Actuation: For energy-sensitive vehicles (i.e., battery electric vehicles), the NEMB System actuates at a fraction of the power required to actuate competing electro-mechanical systems. In addition, the system can be back-driven which provides two benefits: (1) the system will automatically release if no power is provided and (2) the system can regenerate the energy used to actuate and feed it back to the vehicle.
- Zero Brake Drag: The Remmen Zero-Drag (RZDTM) mechanism allows each brake caliper to fully lift the pads off the brake rotor. This essentially eliminates brake drag and can provide up to a 10% savings on fuel consumption in Internal Combustion Engine vehicles or 10% improvement on range in Battery Electric Vehicles. In addition, brake particulate emissions are reduced as the pads are only in contact with the rotor when braking is commanded.
- Integrated Parking Brakes: There is no need for a separate parking brake function as the parking brake can be integrated within each NEMB caliper. The parking brake mechanically locks the calipers in the parking position without the need for additional electrical inputs.
Comparing Braking Performance
The faster actuation times and faster ramp-up profile lead to not only shorter stopping distances but also far better control. Because the brake caliper, at each wheel, can be controlled precisely, the vehicle will no longer experience the pulsing sensations inherent in today’s electro-hydraulic systems during Anti-lock Braking System or Electronic Stability Control activation. Instead, the brake system can pinpoint the torque that it needs to achieve in order to prevent wheel lock and move to that position in a fraction of a second. Doing so will transform the way vehicle dynamics can be looked at and will immensely simplify the controls of vehicle safety systems.
Current Status
The NEMB has undergone an extensive program of testing and has been embedded on a test mule for real-world application testing. The Remmen team is working on integrating the system on a Canadian, government funded project to be completed within the coming years.
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