Recientemente la noticia de los coches que se quedan acelerados a tope ha provocado un enorme revuelo en todo el mundo y principalmente en EEUU. Comprobamos en video que la mayoría de los coches normales pueden frenar incluso con el acelerador apretado a fondo a cualquier velocidad.
http://www.youtube.com/watch?v=QUq8COcQRcc
To begin with, I will make it clear that an issue that has caused at least one fatal accident is not a joke nor is it the intention of this article.
Memory my student days in which, among other things, I calculated brakes and gadgets of that style. The usual in most cars is that lThe brakes are dimensioned in such a way that they can dissipate several times the power of the motor, at least for a short period of time. With this basic approach I launched myself onto a deserted road with a camera in my hand find out if really an engine is capable of overcoming the brakes…in the video it is clear that it is not.
Some control units can stop accelerating if the brake pedal is pressed. To avoid this I tried three different cars, two modern (with instantaneous consumption indicator and turbo pressure gauge) and another without an old one without any type of electronics.
The old car is powered by carburetor, throttle-by-wire and breaker ignition... come on, without a control unit of any kind, so it is certain that the engine was going at maximum power. During the test in modern cars, the instantaneous consumption did not drop, as did the turbo pressure, so presumably the engine continues to deliver maximum power even so. In addition, it is the basis for driving braking with the left foot 🙂
In all of them, the brakes stopped the car until stalled from 3rd gear to full revs, that is, at about 130 km/h and about 14 hp of engine power..
I have no idea how that fatal accident could have occurred in which they claimed the car burned the brakes. The truth is that the Lexus in the accident possibly has more than 200 hp but seeing how quickly 140 hp cars can stop, I doubt that a 200 hp can't stop. Also I didn't hit the brakes too hard to avoid unnecessarily mistreating the cars, so it could even brake faster.
I don't know...someone shed some light on this.
PS: if the car is manual... all this is unnecessary, just step on the clutch, logically.
The problem is that the Prius, as well as other hybrids such as some Lexus, is that the brake is controlled by the control unit, not by the pedal, since the first thing that acts is the motor to generate electricity for the batteries. Then when the control unit detects that you want to brake hard, the normal brake circuit acts.
If there are contradictory or impossible orders, of sensor failure, that is where the strange behavior appears.
The problem with stopping an accelerating car is when the brake does not go by direct command of the foot, that also happens with other devices such as the ASR if you use chains, since it is not capable of handling the car compartment with chains, since the wheel grab and skid depending on whether you are stepping on the wheel or the chain, you really want the wheel to skid to work the chains. On the other hand, with ice and without chains, it works well.
Well, that's a different problem, associated with the campaign to review the ABS software and regenerative braking management. In the event that the accelerator gets stuck or the regenerative braking fails, pressing hard on the brake would act directly on the hydraulic system, as in traditional cars.
regards