Even though in our country (the Czech Republic) we don't have sand dunes, almost everywhere is accessible via paved roads, and we only experience heavy snowfalls a few times a year, I have preferred vehicles with 4x4 drive for many years. I simply like the assurance that if I happen to find myself on a muddy country road or if a bit more snow falls, I won't have to get out of the cockpit to put on chains or place something under the wheels to climb a hill. However, there was a time when I used a car with only front-wheel drive, and then I started to consider whether a car made as a front-wheel drive could somehow be upgraded to at least a temporary four-wheel drive. I immediately dismissed the idea of mechanically transferring driving force directly from the engine, but I was inspired by cars that have been appearing for some time and are even becoming more common, where the front axle is driven by a conventional combustion engine, while the rear wheels are powered by an electric motor - thus making it a hybrid drive, which also turns the car into a four-wheel drive, even though reviews of these systems are not always flattering. But how to fit another power unit into a car that has a relatively simple rear axle without drive shafts and space for an engine? That is precisely the subject of my idea, which may never be realized, but seems quite interesting to me. The thought is that two electric motors, each for one wheel, would somehow have to be integrated directly into the wheel. If you look at what is inside a rim today, the significant space in most cars is occupied by the brake, usually disc brakes in larger passenger cars, and drum brakes in smaller ones. Each such brake consists of a part that rotates with the wheel, the "rotor," and then we have brake pads, which are instead fixedly connected to the rest of the vehicle, which is essentially the "stator." Rotor and stator, these are common components of an electric motor. If we could produce a brake disc or drum that, in addition to its normal braking function, integrated sufficiently strong permanent magnets and was made of a non-magnetic material (e.g., carbon composite combined with ceramics) and at the same time we could integrate electrical windings into the brake pads, we could essentially create a synchronous electric motor and a mechanical brake in one. Through conductors run along with the brake hoses, the electrical winding could be connected to a control unit with a battery in the form of a box placed in the trunk of the vehicle, and through the CAN communication bus, this box would connect to the car's control electronics - from there, it would then receive, for example, information about the position of the accelerator pedal, the demand for braking force would then be given by the brake lining itself. With these means, we could then generate electrical energy with the synchronous electric motor when activating the brakes (or also during normal driving if necessary) and store it in the accumulator of the control box, on the other hand, when pressing the accelerator pedal and releasing the brakes, we would use electricity from the accumulator to rotate the synchronous motor, thus aiding the vehicle's acceleration, and thus the powered rear axle would make a vehicle with originally only front-wheel drive into a four-wheel drive and simultaneously a hybrid, which could even reduce fuel consumption.
If it were possible to construct the described "hybrid/active" brake discs or drums and pads with electrical windings in such a way that these new components could directly replace the original "passive" components, then they could be manufactured for almost any brand and type of vehicle. Any auto service could handle the installation, with the only more complex task being the routing of cables from the windings in the pads to the control box in the trunk of the vehicle. The connection to the accelerator pedal or other systems in the car could then be facilitated by a wireless communication adapter to simplify installation.
So, does your company manufacture brake discs or pads, and would it be interesting for you to try making them into electric motors as well?
Do you have an older front-wheel drive car and would like to turn it into a reasonably priced hybrid four-wheel drive?
Is this idea just a technical nonsense, or is it a feasible concept worth pursuing?
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