Now and then, old habits have to make room for new vehicle technology. That is also the case for the electronic brake systems that are frequently used in hybrid vehicles. They may be more accurate than traditional brakes when it comes to dosing and developing their effect, but drivers lose that typical braking sensation when they press the brake pedal. The pedal still triggers the braking procedure, but the brakes are actuated by an electronic system. Mechanically, they are completely decoupled from the brake pedal. "But that also takes away the accumulating braking resistance that drivers feel in the pedal, which enables them to brake with all of the relevant senses at the same time," explained Frank Möllering, sales manager in the Sealing Systems Chassis segment at ContiTech Vibration Control.
Brake servo units work with underpressure that is also supplied by combustion engines. In hybrid vehicles on the contrary, a vacuum pump generates the underpressure - either because there is no longer a combustion engine or because it functions as a charging station for electric engines. If that is the case, it would always run at low speed and therefore produce too little underpressure. The brake pedals in hybrid vehicles have a triggering function only: braking resistance no longer builds up in the pedal.
ContiTech has developed the rubber spring used in a braking simulator to provide drivers with the resistance they are used to - and Ford USA is using this braking simulator in series production. The molded part shaped like a pyramid is slightly larger than a box of matches. The rubber spring is part of a small box with a circular opening that receives a shaft extending from the pedal at a right angle. A connecting rod that diverts the lever action of the brake pedal to the interior of the box is located on the shaft. The working chamber of the connecting rod is restricted by the rubber spring.
When the brake pedal is pressed, the end of the connecting rod moves toward the rubber spring and compresses it. That creates a braking sensation in the pedal foot. "Depending on the rubber spring's degree of hardness and the shape of its roof, we can simulate different types of braking effect: from sporty to comfortable," explained Möllering.
The rubber springs can have different roof shapes and, depending on the material mix, they respond to the mechanical pressure sharply or gradually. "We are able to provide vehicle manufacturers with rubber springs that are configured according to customer specifications," said Möllering. "In the braking simulator, the braking resistance of individual vehicle types can be simulated."
In addition, a special pedal stop developed by ContiTech cushions the rebound of the brake pedal when the braking procedure is completed. The molded part is also inside the box, opposite the rubber spring on the other side of the connecting rod. "The pedal stop is another area of comfort improvement," he said. "It prevents clicking noises that may interfere with the driving experience."
Brake servo units work with underpressure that is also supplied by combustion engines. In hybrid vehicles on the contrary, a vacuum pump generates the underpressure - either because there is no longer a combustion engine or because it functions as a charging station for electric engines. If that is the case, it would always run at low speed and therefore produce too little underpressure. The brake pedals in hybrid vehicles have a triggering function only: braking resistance no longer builds up in the pedal.
ContiTech has developed the rubber spring used in a braking simulator to provide drivers with the resistance they are used to - and Ford USA is using this braking simulator in series production. The molded part shaped like a pyramid is slightly larger than a box of matches. The rubber spring is part of a small box with a circular opening that receives a shaft extending from the pedal at a right angle. A connecting rod that diverts the lever action of the brake pedal to the interior of the box is located on the shaft. The working chamber of the connecting rod is restricted by the rubber spring.
When the brake pedal is pressed, the end of the connecting rod moves toward the rubber spring and compresses it. That creates a braking sensation in the pedal foot. "Depending on the rubber spring's degree of hardness and the shape of its roof, we can simulate different types of braking effect: from sporty to comfortable," explained Möllering.
The rubber springs can have different roof shapes and, depending on the material mix, they respond to the mechanical pressure sharply or gradually. "We are able to provide vehicle manufacturers with rubber springs that are configured according to customer specifications," said Möllering. "In the braking simulator, the braking resistance of individual vehicle types can be simulated."
In addition, a special pedal stop developed by ContiTech cushions the rebound of the brake pedal when the braking procedure is completed. The molded part is also inside the box, opposite the rubber spring on the other side of the connecting rod. "The pedal stop is another area of comfort improvement," he said. "It prevents clicking noises that may interfere with the driving experience."
