There is a currently a well-known tendency in the automobile industry to opt for technological solutions which aim at reducing consumption.

The aim of the present invention is to use the electric fan group of the radiator to generate electrical energy during the phase in which the electric fan itself is not in use so, on the other hand, the fan is turned by the fluid dynamic energy of the air flow inducted by the engine of the vehicle.

Normally, the above-mentioned energy is not used; therefore the fan, when it is not supplied by the electric motor, turns at an extremely fast rate to reach the speed at which is dynamically in equilibrium with the speed of the air. This situation occurs whenever the airflow generated by the vehicle's engine is in itself sufficient to cool the radiator.

Even if the amount of energy recuperated is in

the order of a few dozen watts, it should be borne in mind that in the context of the overall amount of energy these watts must be multiplied by approximately two in that otherwise said energy will be supplied by the aboard alternator, with an efficiency rate equal to about 50%.

The present invention is particularly relevant and interesting when considered in the context of electric fans which are electronically controlled in speed, in that said invention can achieve the aim described above at practically no additional cost, the only addition necessary being to add a management logic function to the control logic function of the machine itself in such a way that it can be made to function as a generator.

Toward the attainment of these and additional objects and advantages, which will be better understood later, the invention provides a system for energy recovery in electric fans of radiators, the system comprising at least a power supply, which is connected to an electronic control device, operated by a pilot electronic-box and coupled to an electric machine, able to start at least one cooling fan; the system being characterised by the fact that a pilot circuit is placed between said electronic control

device and said electric machine so that the electric machine may be configure like a motor for the fan of like a controlled generator operated by the fan itself, said electric machine being controlled by an application program for computers able to conduct the electric machine in function of sizes or parameters inside the system and/or commands outside the system.

The system according to the present invention will now be describec in detail with reference to the attached drawings, in which: FIGURE 1 is s block diagram of an electric fan group for a car; FIGURES 2 - 6 are wiring diagrams and diagrams of the system according to the invention as applied to an electric fan group for a car.

Figure 1 illustrates a block diagram of the functional aspects of an electric fan group for a car radiator.

A indicates the air flow, V indicates the fan, M indicates the electric machine (motor/generator), CM indicates the electronic control for the latter, F indicates an electric filter placed between CM and <BR> <BR> <BR> <BR> <BR> <BR> <BR> the battery, which is indicated by B, so as to smooth the harmonics of the current, and CC indicates a <BR> <BR> <BR> <BR> control unic outside the motor which, according to

the variables imposed by different car manufacturers (such as air temperature, vehicle speed etc) sends input to CM to control the functions of the fan (ON, OFF, rotation speed etc).

The system configure in Figure 1, where the machine M is operated by CM as a motor only, is one o_ the well-known systems which is normally in use nowadays.

As has previously been explained, with regard to cost, the present invention does not substantially alter the functional blocks shown in Figure 1, but is applied only the form of the block CM which provides "bridge"commandstructure.fora The present invention provides for, in particular: a) integrating the system with an input logic <BR> <BR> <BR> <BR> <BR> which permits the transformation of the electric controlledmotortocontrolledmachinefrom generator; b management software for the machine as a generator in the block CM which can, ir. accordance with the needs of various clients, control the therequiredspeedandlimitcurrentgeneratorat flow either to maximum fixed levels or in accordance withofthebattery.voltage

It is possible to obtain, by means of this alternative, the automatic control management of the whole of the"braking phenomenon"exercised on the fan turned by the air flow, in such a way as to guarantee maximum energy transference from fluid dynamos to electricity (recharging of the battery).

In the interests of simplicity of description, let us now refer to a motor which functions by electronic switching, the simples form of which is a single-phase structure. This reference is made solely in the interests of describing the operating principe, taking into accourt that in reality these kinds of motors would in fact generally be two phase, three phase or five phase. The operating principle described according to the single-phase alternative, however, provides a full explanation of how other <BR> <BR> <BR> <BR> <BR> machines with more phases function according to techniques.currentwell-known <BR> <BR> <BR> <BR> <BR> The basic circuit usually starts from a bridge<BR> <BR> <BR> <BR> <BR> <BR> <BR> structure as indicated in Figure 2. The bridge structure provides, in a single phase structure, for four power switches P1, P2, P3, P4, which are fixed to the ends of the suoply wires which place a filter CF between the bridge itself and the battery B, in its simplest form the filter is just a condenser.

Inside the bridge is the winding of the machine which as an equivalent network can be expressed as an electromotive force E, a winding resistance Ra and a winding inductance La.

When the machine functions as a motor, the control unit CC, which controls the above-mentioned switches, operates according to well-known techniques by switching alternately between two half waves S1 and S2 (see Figure 2A) of the electromotive force E, in such a way that, as the voltage supply is unipolar, the sides of the bridge P1, P4 switch alternately by one half wave, or the sides of the <BR> <BR> <BR> <BR> <BR> bridge P2, P3 switch alternately when the other half wave is in operation so that one pair in the machine is always active.

These components, which in the embodiment in question are normally obtained with Mos, comprise a parasitic component in parallel which is traditionally a diode; in Figure 1 each diode is illustrated in association with a switch indicated by D1, D2, D3, D4- When this machine is used as a generator the switches P1 and P2 are no longer necessary and are in fact turned off by the control unit CC, so that the circuit becomes like the one shown in Figure 3, that

is to say that it is simplified into a structure of this kind. There are two upper diodes D1 and D2, two switches P3 and P4 and two other diodes D3 and D4 but as we shall see the latter two do not function normally for which reason they could even be omitted from the illustration as they do not take part in the overall operation of the machine.

In order to understand what happens, it is sufficient to consider that on the half wave Sl, where, for example, the battery voltage is positive, the switch P3 remains closed during the entire period in which the electromotive force E is positive; during this half period, the node J being earthed, (see Figures 2 and 3), the diode D1 is not in operation, so that it seems that it does not exist.

In order to further simplify the functioning on one half wave (it is useless to explain the functioning on the other because it is exactly the same as in this case), the circuit can be further simplified, we can make reference here to the circuit shown in Figure 4, which provides an immediate visual explanation of what happens.

The motor is now shown with the electromotive force E, the inductance La, the resistance Ra, the diode D2 (the diode D1 is not shown because it is no

longer of any use) and with the switch P3 closed (it is shown completely closed, because it remains completely closed throughout the functioning of the half wave).

What happens instead is that the other switch P4 works by impulse modulation, that is to say that it opens and closes according to a certain duty cycle. The diode D2 acts first on the condenser CF which, in turn, acts on the battery B.

What in fact happens during this impulse modulation? The point of the question is how, in fact, the battery B can be charged even though the general electromotive force E of the machine is lower than the battery voltage; for example, at the speed at which the fan is turning, let us assume that the voltage generated inside the electric machine is three volts lower than that of the battery.

If the voltage is three times lower, what <BR> <BR> <BR> <BR> <BR> happens is that when the switch P4 is closed the voltage will make a current pass into the motor, in its inductance La and its resistance Ra, and this current will charge the inductance with a certain amount of energy which corresponds to the impulse at the level of the current. Figures 5 and Sa

illustrate the form of this current 1, according to variations of the charge CB of the battery B, during the ON period T1 and the OFF period T2 respectively.

When the switch P4 is opened, the current that has accumulated energy equivalent to % Lai2 in the inductance La of the machine continues to try and maintain its flow.

When the switch P4 is opened, during the OFF period, the current from the circuit of the switches is set to zero (because it can no longer circulate in this circuit) but it continues to flow during the OFF phase of the circuit regarding the battery.

During the period that P4 is OFF the current which has reached this level suddenly appears via the diode D2, according to the well-known function diagram of a step up, and will then appear in the battery circuit.

It is obvious that this inductance, over a certain period of time, will tend to reduce the current towards the battery, but at a certain point <BR> <BR> <BR> <BR> <BR> the switch P4 will close again; the current in the battery will be reset at zero and from this point the current will reappear in this circuit, which will continue to recharge it.

What happens next is that, notwithstanding the

fact that there is voltage at the beginning of the generator, a certain average current"levelled"by the condenser of the filter CF is supplied to the battery B. Starting from the loss in the circuit, in principle, the product E1 at the input, that is to say the average value of the current which is circulating in the generator at four volts, multiplied four times, will be equal to the value of the voltage of the battery multiplied by the average voltage of the current supplied by the battery, less inthecircuit.theloss In order that this transferred current t can reach maximum level, there is a shunt resistance Rs (a current sensor) in the ba.. ery's return circuit towards the control system, from where the value of the current is taken and integrated via a circuit RC to give the average value IB. Practically, the average value of the current in the battery is obtained, this average value goes to the micro switch which calculates, moment by moment, the average value or the current going to charge the battery in function of the condition of the fan.

Figure 4 illustrates, purely as an example, an electrical circuit R1, C1 of the type RC, via which the values of the currents are integrated over time

with the aim of obtaining an average value 1B, which is then transferred as input to said electronic control device CM.

When the first half wave is finished the Hall sensor, or any other type of. Rs sensor which can transmit to the machine that the other half wave is beginning, moves the function to the other half of the machine, which is to say that on the other half <BR> <BR> <BR> <BR> <BR> <BR> wave it will be P4 which remains closed and P3 which functions in Pwm, while D2 will not function any more and D1, instead, will be active in the circuit.

As can be seen from the embodiment, the bridge structure is absolutely fundamental so that the machine may effectively function as a generator as well as an electric motor using exactly the same components.

In fact, thanks to this structure, no additional power components are added and nothing has been done other than to change the piloting logic of the electric switches. A different software management is, therefore, sufficient so that it can carry out the management of the switching of the machine in such a way that it looks to either the speed of the machine, or the value of the current, and limits it; that is to say, it applies a logic

which causes the machine to function as a generator.

The machine, instead of being of the single- phase type, can also be a two-phase bridge structure, a three-phase bridge structure, or a five- phase bridge structure.

In the case of permanent magnet electronically controlled direct current brush motors (not brushless motors, as have been dealt with up till now), the same considerations hold good as for the single phase brushless structure with circuit simplification which, being without an alternated F. E. M., only need a semi-bridge structure to achieve the above- mentioned aims. (see Figure 6).

In this case when the machine is functioning as a motor P1 is impulse controlled while P2 is OFF, when the machine is functioning as a generator P1 is OFF and P2 is impulse controlled.

In both cases the loss of voltage on Rf transmits information to the control motor CM concerning the current in the motor for the same reasons as those mentioned above.

It should also be mentioned, in conclusion, that the functions of the diodes (D1, D2) can also be carried out by the same switches (P1, P2) being set to the ON position during the time in which it is foreseen that they will act as conductors for the diodes.