Recuperation, what a difficult word. The necessary information behind it is just as difficult. The generator, which is regulated by the engine management is relatively simple. You can read about this here. Some manufacturers even sell this as a complete system. As long as one zealously downshifts, it functions very well. Indeed, taking a look at the normal traffic situatuion, shows that a decrease in speed very often is the result of braking.
In this case, the energy from the brake, which is converted into heat, is not available for the recuperation. It would be far better if the energy was fed to the generator through only lightly applying the brakes, so gently in fact, that the brake pads would not even touch the discs. Such a system has been developed, e.g., by Honda. It is however, complicated and expensive because it acts on the main brake-cylinder. Thus, it is no longer a mass- produced and supplied component, which makes it expensive in the case of a repair.
In our described system, only the ABS/ESP controller is replaced. Through it's, also altered, control device, the course of the braking-action is observed. As long as the braking is caused by the engine, there are hardly any problems. The moment the vehicle is to be brought to a standstill by a slight pressure on the pedal, the running motor can't handle it. The brake must take over the action again. This means, that the electric ESP/ABS-pump is needed in the normal course of events and not only in the case of an emergency.
Systems like the one in Honda are so complicated because, in addition, the driver should not be aware of what's going on. Should the pedal-pressure in any situation, feel any different than usual, it could lead to a dangerous situation as far as traffic safety is concerned. This is why this type of system, e.g., the SBC in Mercedes (Sensotronic Brake Control) feign such a pedal pressure and apply the brakes, except in case of an emergency, only with the help of a pump.
This system allows the connection to the front wheels to be maintained and has thus, a high amount of pressure stability. However, at the moment, this is only possible with a strictly defined allocation. Thus, recuperation takes place together with the braking effect on the front wheels, although it is, at least, activated by the braking system. The driver must not deliberately ease off the pressure on the gas pedal. The fine adjustment takes place through the brakes on the rear axle.
It would be interesting to know, just how much energy would remain for the generator, because the front brakes, particularly during partial braking, do a great deal more for the energy absorption than do the rear brakes. Here one can also see, just how careful the manufacturers are when it comes to changes in the customary braking system. They are far too afraid that it it could, once again, cause another campaign like the one which took place in the USA against Audi and Toyota.
Oh yes, the above shown valve-block is not necessarily thicker because of the greater amount of valves. The electric pump here, works with six pistons instead of only two, making it distinctly quieter. After all, it is now used during normal driving operation where louder noises would diminish the comfort. Try out your 'normal' ABS-
function on a snow-covered side road (making sure that no-one is behind you), then you'll be able to hear the 'normal' pump noises. 09/12
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