GB2160683A

GB2160683A - Automatic control of the temperature of air introduced into the passenger compartment of a vehicle

Info

Publication number: GB2160683A
Application number: GB08514484A
Authority: GB
Inventors: Antonio Nigra
Original assignee: Gilardini SpA
Current assignee: Marelli Europe SpA
Priority date: 1984-06-08
Filing date: 1985-06-07
Publication date: 1985-12-24
Also published as: GB2160683B; ES8607130A1; IT8467590A0; FR2565532A1; IT8467590A1; IT1179713B; DE3519466A1; GB8514484D0; ES543943A0

Abstract

A system for automatic control of the temperature of air introduced into the passenger compartment (8) of a vehicle with a heat engine has an auxiliary radiator (1) connected to a cooling water circuit (2,3) of the engine, and a fan (4) for making the air which is conveyed into the passenger compartment (8) pass through this radiator (1). The system includes a cock (11) controlled by an electric motor for regulating the quantity of water which passes through the radiator (1), and an electronic circuit (12) for detecting the air temperature in the compartment (8) with respect to a predetermined set value and consequently controlling the electric motor which opens and closes the cock (11). Sensor (16) is responsive to the temperature of ambient air in the vehicle, which a sensor (13) responds to the temperature of air in the duct (6). The sensor signals are proportionally combined. <IMAGE>

Description

SPECIFICATION A system for automatically controlling the air temperature introduced into the passage compartment of a vehicle having a heat engine The present invention relates to a system for automatically controlling the temperature of air introduced into the passenger compartment of a vehicle having a heat engine, conveniently a motor car, of the type comprising an auxiliary radiator connected in a cooling water circuit of the engine, and means, conveniently fans, for making air which is conveyed into the passenger compartment traverse this radiator through convenient diffusion apertures.

The quantity of coolant water which passes through this auxiliary radiator can conveniently be regulated by means of a cock, and similarly the quantity of air which is conveyed into the passenger compartment can be regulated both via a regulation of the fan means and by regulation of the cross sectional area of diffusion apertures for such air. However, because of the variable external temperature conditions and speed of the vehicle, temperature fluctuations can occur within the vehicle, which makes it necessary to effect continuous manual adjustment of the temperature within the passenger compartment.

The object of the present invention is that of providing a system for the automatic control of the temperature of air introduced into the passenger compartment of vehicles having heat engines, which overcomes the above indicated disadvantage, that is to say it allows a substantially constant temperature to be obtained within the passenger compartment, equal to a set temperature value and independently of variations in the speed of the engine, the speed of the vehicle and the external temperature.

Other objects and advantages obtained with the system of the present invention will become apparent from the following description.

According to the present invention there is provided a system for the automatic control of the temperature of air introduced into the passenger compartment of a vehicle having a heat engine, comprising an auxiliary radiator connected into a cooling water circuit of the said engine, and means for making the said air which is conveyed into the passenger compartment traverse through the said radiator, characterised by the fact that it includes a cock controlled by an electric motor for regulating the quantity of said water which passes through the said auxiliary radiator, and an electronic control circuit for detecting the temperature of the said air in the said passenger compartment with respect to a desired set value and consequently controlling the said electric motor.

For a better understanding of the present invention a particular embodiment is now described purely by way of non limitative example, with reference to the attached drawings, in which: Figure 1 is a schematic view of the main component elements of the system of the present invention; Figure 2 is an electric diagram of a motorised cock belonging to the system of the present invention; Figure 3 is a sectioned side view of the valve utilised in the system of Fig. 1; Figure 4 is a view from above of a printed circuit present in the control circuit of Fig. 2; and Figure 5 is an indicative illustration of the variation with time of some of the signals present at a certain point of the electric control circuit of Fig. 2.

With reference to Fig. 1, there is shown with the reference numeral 1 an auxiliary radiator of known type hydraulically connected to inlet ducts 2 and outlet ducts 3 in such a way as to be traversed by the water of the cooling circuit of a heat engine; opposite this auxiliary radiator 1 there is disposed a fan unit 4, conveniently one having different selectable speed of rotation, also of known type, whilst on the opposite side of this radiator 1 there is disposed a body 5 for collection of the heated air, which has ducts 6 and 7 for conveying the air to different regions of a passenger compartment 8 of a motor vehicle.

In the inlet duct 2 there is fitted, in series, as elements for regulating the flow of water, a unit 10 comprising a flow regulating cock 11 and an electronic monitoring and control unit 12 to which are connected: -a first temperature detecting sensor 1 3 disposed in the duct 6 upstream of a nozzle 14 about which is disposed a second duct 1 5 which leads into the passenger compartment 8;; -a second temperature detector sensor 1 6 mounted on a dashboard 1 7 of the vehicle, disposed within a hollow body 1 8 mounted on the dashboard 17, having a front cover 1 9 with holes in to allow the ingress of air, and having a lateral output tube 20 to which is connected a duct 21 which leads into an initial portion 22 of the duct 1 5 upstream of the nozzle 14; -and a potentiometer 24, conveniently having a cursor 25 for setting the desired temperature in the passenger compartment 8.

The electronic monitoring and regulation unit 12, illustrated in Fig. 2, has a first differential amplifier 27 which has a first input 28 to which is connected a terminal of the potentiometer 24, whilst the other terminal is connected to earth, and has a second input 29 to which is connected a terminal of the sensor 13, whilst the other terminal is connected to earth. Between a positive voltage supply terminal and earth there is connected a series of three resistors 31, 32 and 33 and the connection between the resistors 31 and 32 is also connected to the input 29 of the amplifier 27, whilst the connection between the resistors 32 and 33 is connected to a first terminal of the sensor 1 6 the other terminal of which is connected to earth.

The output of the differential amplifier 27 is connected to an input 34 of a differential amplifier 35 forming a frequency modulated oscillator, and having another input 36 which is connected to earth via a capacitor 37; between the input and output of the amplifier 35 there is connected a resistor 38, whilst the output of the amplifier 35 is connected to an input 39 of a differential amplifier 40 forming a decoupling circuit, and having another input 41 connected to earth; between the input and output of the amplifier 40 there is connected a resistor 42.

The terminals of the sensors 1 3 and 1 6 which are not connected to earth are connected, respectively, via resistors 43 and 44 to a first terminal of a capacitor 45, the other terminal of which is connected to earth through a resistor 46, and to an input 47 of a differential amplifier 48.

The terminal of the sensor 37 which is not connected to earth is also connected to one end of a resistor 50 the other end of which is connected to an input 51 of the amplifier 48, and to earth via a capacitor 52. The terminal of the sensor 1 6 which is not connected to earth is in turn also connected to a first end of a resistor 53 the other end of which is connected to the input 51 of the amplifier 48 and to the capacitor 52 which is connected to earth at its other terminal. The output of the differential amplifier 48 is connected, via a resistor 54, to the input 34 of the differential amplifier 35.

The output of the differential amplifier 40 is connected to the base of an NPN transistor 55 the emitter of which is connected to earth and the collector of which is connected to the cathode of two diodes 57 and 58. The anode of the diode 57 is electrically connected to two diametrically opposite and relatively short sectors 60 and 61 disposed on a first circular track 62. The anode of the diode 58 is on the other hand connected to a positive voltage supply terminal via a resistor 63 and to the base of an NPN transistor 64 the collector of which is connected to another two diametrically opposite relatively short sectors 65 and 66 equally spaced with respect to the sectors 60 and 61 of this track 62.The emitter of the transistor 64 is on the other hand connected both to earth and to four relatively long sectors 67 which are electrically connected together and interposed between but insulated from the various short sectors, 60,61, 65 and 66 on this track 62. Coaxial with this track 62 there is a second, continuous circular track 68 of smaller radius, which is connected to the first terminal of an electric motor 70 which controls the actuation of the cock 11 in a manner which will be described in more detail below, and the other terminal of which is connected to a positive voltage supply terminal. Coaxial with the tracks 62 and 68 there is a brush 71 (indicated in broken outline) having two wiper arms 72 and 73 of different length, the first of which is in contact with the track 68 whilst the second is in contact with the track 62.

The unit 10, structurally indicated in Fig. 3, includes two half shells 75 and 76 conveniently made of plastics material and connected together by means of a hermetic perimetral junction 77, for example by means of a hot blade, which form the cock 11 with the various internal component elements which will be described, and to the lower half shell 76 there is connected, also in a manner which will be described in more detail, a body 78 containing the monitoring and control unit 1 2. This container body 78, having regions of different depth and having an upper aperture of substantially rectangular form, is closed at the top by a cover 79, fixed for example by means of screws, not visible, which carries integral upper support columns 80 on which rest a plurality of positioning webs 81 integral with the lower half shell 76 and fixed on the columns 80 by means of screws 82.

The various internal componets of the container body 78 are further positioned by a conveniently shaped internal diaphragm 83 which moreover has positioning walls 84 and small feet 85 for insertion into respective cavities 86 of the body 78. Between the inner diaphragm 83 and the bottom of the body 78, conveniently supported by projections 87, the electric motor 70 is positioned, surrounded by a convenient sheath 88 of rubber and having an output shaft 89 on which is secured a toothed wheel 90 which meshes with another toothed wheel 91 which is coaxial with and fixed for rotation to a toothed wheel 92 (toothed wheels 91 and 92 are positioned between the inner diaphragm 83 and the cover 89) and the toothed wheel 92 meshes with a toothed wheel 93 rigidly connected to a hub 94 which is positioned between the inner diaphragm 83 and the cover 79 and which in its interior carries, secured thereto, a spindle 95 which projects above the cover 79 and passes through the cock 11 to control it in a manner which will be described.

On the lower end of the spindle 95 there is fixed the brush 71 which slides on the tracks 62 and 68 formed as printed circuits on a plate 96 which is supported in position by the container body 78 by means of columns 97 having upper pins 98 which enter into corresponding holes 99 of the plate 96 (as seen better in Fig. 4); this plate 96 is further supported by projections 100 of the container body 78 and between this plate 96 and the inner diaphragm 83, in correspondence with the upper pins 98, there are interposed resilient cylinders 101.

The other circuit element of the monitoring and control unit 12 illustrated in Fig. 2 are housed in this container body 78.

The lower half shell 76 has an upper chamber in which is positioned a disc 102 conveniently made of ceramic material, which is fixed against rotation to the half shell 76 by coupling to a radial projection of the respective cavity, and which has an outer perimetral sealing ring 103. This disc 102 has two diametrically oppositely positioned circular through holes 105 which open into an annular chamber 106 formed in the lower region of the half shell 76, and which is in communication with the outside through a radial tube 107 which is connected to the duct 2 of Fig.

1. On the disc 102 rests another disc 108, conveniently made of similar material and urged by a spring 109 which at the other end engages on an inner annular web 110 of the upper half shell 75. This disc 108 has a pair of through holes 111 of shaped section better visible in Fig. 4, which open out at the top in communication with a half annular chamber 11 2 which is in communication with the outside through a radial tube 11 3 which is connected to the duct 2 of Fig. 1 to receive the incoming water.The spindle 95 which passes through the half shells 75 and 76, traverses an axial circular hole 11 5 of the disc 102 and has a portion 11 7 of greater section and of non circular profile which is positioned in a corresponding aperture 11 6 of non circular section in the disc 108 to fix them together for rotation. This spindle 95 which has an upper notch 118, then passes axially through the inner annular web 110 and projects from the upper half shells 75 through a sealing unit 11 9 substantially of known type and locked from above by a small cover 1 20 fixed by means of screws (not visible onto an outer upper flange 121 of the upper half shell 75.An hydraulic sealing unit 122 similar to the unit 11 9 is disposed about the spindle 95 in the lower region of the lower half shell 76 and is locked from below by a small cover 1 25 which is fixed by means of screws 1 25 onto the bottom of the lower half shell 76.

With reference to Fig. 4, there is illustrated on an enlarged scale the plate 96 on which are formed, as printed circuits, the inner circular track 68 having a radial section 1 26 with terminals 1 27 for connection to terminals of the electric motor 70 in accordance with the diagram of Fig. 2, the sectors 60,61,65 and 66 with the respective terminals 60',61' for connection to the anode of the diode 57, and 65',66' for connection to the collector of the transistor 64, and the four interconnected intermediate sectors 67 of the track to a terminal 67' for connection to earth, and to the emitter of the transistor 64, as in the diagram of Fig. 2.As is easily seen in Fig. 4 in which the fixed and rotating discs 102, 108 are shown in broken outline, the apertures 105 of the fixed disc 102 are disposed angularly in correspondence with the sectors 60 and 61 of the first circular track 62, whilst the through holes 111 of the rotating disc 108 can obviously assume a variable angular configuration with respect to these apertures 105, and in Fig. 4 are illustrated in correspondence with the sectors 65 and 66 so that the cock 11 is substantially closed.

The operation of the system of the present invention described above, as well as the cock and the electronic monitoring control unit are as follows.

With reference to Fig. 1, the air which is to be introduced into the passenger compartment 8 is made to traverse the auxiliary radiator 1 by means of the fan unit 4 and then is conveyed through the ducts 6 and 7.

The sensor 1 3 disposed in the duct 6 consequently provides an electrical signal in dependence on the temperature of the air heated more or less, which is introduced into the passenger compartment 8, whilst the sensor 1 6 disposed on the dashboard 1 7 provides an electrical signal proportional to the temperature of the ambient air in the passenger compartment 8; in particular, the presence of the duct 21 and its outlet arrangement upstream of the nozzle 1 4 ensures that there is a circulation of air which from the passenger compartment 8 enters into the hollow body 1 8 in which the sensor 1 6 is contained, thus flowing over this and, through the tube 20 of the duct 21 discharges towards the duct 15 leading back to the passenger compartment 8, so as to make the sensor 1 6 sensitive to a more homogeneous value of the temperature of the air in the passenger compartment 8.

The two electrical signals provided by the sensors 1 3 and 1 6 are compared in the monitoring and control unit 12, in a manner which will be explained in more detail below, with the reference temperature signal preselected by a user by means of the cursor 25 of the potentiometer 24, such that, in dependence on the differences with respect to the set temperature value, there is obtained a proportional regulation of the rate of flow through the cock 11, and therefore a proportional regulation of the quantity of heat provided to the auxiliary radiator 1, which in turn yields it to the air collected in the body 5 and then conveyed to the passenger compartment 8.

With reference to Fig. 2, the electrical signals provided by the sensors 1 3 and 16, conveniently proportioned among themselves by means of the network formed by the resistors 31,32 and 33 in dependence on the characteristics of the various elements of which the system is composed, and on the vehicle on which this is fitted, are supplied to the input 29 of the differential amplifier 27 and are compared with the signal provided at the input 28 and set by means of the potentiometer 24. The signal at the output of the amplifier 27 is a function of the difference between the temperature within the passenger compartment and the desired temperature, and is passed to the differential amplifier 35 acting as a frequency modulated oscillator with variable duty cycle, which provides at its output a signal of the type illustrated in Fig.

5a in which, within constant periods of a duration of about five seconds, and delimited by vertical lines, the duration of the positive square wave varies. The output of the amplifier 35, through the de-coupling unit comprising the differential amplifier 40 provides a control signal, illustrated in Fig. 5a, for the transducer 55.In particular, with the signal of Fig. 5 at the zero level, the transistor 55 is switched off, whilst the transistor 64 is in conduction; in these conditions the sectors 60 and 61 of the outer track 62 are at a substantially positive voltage at a higher level, whilst the sectors 65 and 66 are substantially earthed; consequently, supposing that the brush 71 (which at rest always remains positioned in correspondence with one of the two pairs of sectors) were positioned in correspondence with the sectors 65 and 66 so that, as illustrated in Fig. 4, the cock is substantially closed, the electric motor 70 is fed with current so that, through the toothed wheels 90, 91,92 and 93 (Fig. 3) it makes the spindle 95 and the brush 71 and movable disc 108 rigidly connected thereto rotate so that the supply to the electric motor 70 continues for the angular sector in which the arm 73 slides on the sector 67 of the track 62, and when this arm 73 reaches the sector 60 or 61, these being subjected to a positive voltage, the motor 70 stops thus achieving conditions of opening of the cock in that the apertures 111 are disposed in correspondence with the apertures 105 of the fixed disc 102.

This condition of opening of the valve 11 remains for the whole of the time from to to t (Fig. 5a) in which the said conditions of polarisation to the sectors 60,61,65 and 66 remain. On the other hand, if the brush 71 were already in correspondence with the sectors 60 and 61 corresponding to the condition of the cock 11 being open, this condition would remain without any movement of the electric motor 70.

At the instant t, in which the signal of Fig.

5a becomes positive, the transistor 55 is put into conduction whilst the transistor 65 is switched off so that the sectors 60 and 61 are now earthed, whilst the sectors 65 and 66 are supplied with a positive voltage. Consequently, the brush 71 being in correspondence with the sectors 60 and 61, current is supplied to the electric motor 70 which then turns until the brush 71 is positioned in correspondence with the sectors 65 and 66, and with the corresponding rotation of the movable disc 108 the cock 11 closes and remains in this closed condition for the time from t, to t2 In the subsequent period, in dependence on the different signals provided by the differential amplifier 27, the interval (t2-t3) varies with respect to the the interval (to-t,) in which the cock 11 remains open, and thus similarly for subsequent periods, in this way obtaining a regulation, for each period, of opening time for the cock (in dependence on the difference encountered between the effective value of the temperature of the air in the passenger compartment 8 and the desired set value) and consequently obtains a variation in the rate of flow of water through the cock 11 and a variation of the quantity of heat which traverses the auxiliary radiator 1 is provided to the air conveyed towards the passenger compartment 8.

As illustrated in Fig. 5b, in the case that the temperature in the passenger compartment 8 is substantially greater than that set, the cock 11 remains closed continuously, whilst in the case that the temperature in the passenger compartment 8 is substantially less than the set value, the cock 11 remains open for a longer or shorter time equal, in different periods, as illustrated in Fig. 5c, to the control signal to the transistor 55.

The circuit unit comprising the differential amplifier 48 further provides a correction signal to the input 34 of the amplifier 35 in dependence on the speed of variation in time of the signals provided by the sensors 1 3 and 16, and which is introduced at the inputs 51 and 47 respectively by means of integrating and differentiating networks.

As illustrated in Fig. 2, parallel with the transistor 55 there can be disposed a switch 1 30 indicated in broken outline, which can be actuated to close in the case of failure of the electronic control circuit of the transistor 55 to determine connection to earth of the cathodes of the diodes 57 and 58, and therefore connection to earth of the sectors 60 and 61 whilst the sectors 65 and 66 are supplied with positive voltage in that the transistor 64 is switched off and therefore the conditions obtain of supply to the motor 70 such that the cock is disposed in a closure position.

A mechanical positioning of the movable disc 108 can further be obtained by means of a rotation from the exterior of the spindle 95 by inserting, for example, a screwdriver into the upper notch 118.

The advantages obtained with the described system of the present invention are apparent, in that in the passenger compartment 8 the desired temperature set by means of the potentiometer 25 is obtained constantly independently of the speed of rotation of the zone of the said duct leading from the said auxiliary radiator to the said passenger compartment.

1 3. A system according to any of Claims from 8 to 12, characterised by the fact that the said third circuit means comprise comparator means for comparing the said first electrical signal and a second electrical signal provided by the said second means and operable to provide a third electrical signal to frequency modulator means which, via successive circuit means provides a fourth electrical signal at two levels for the control of the said electric motor.

14. A system according to Claim 13, characterised by the fact that to the input of the said frequency modulator means, as well as the said third electrical signal, there is provided a fifth electrical signal coming from detector means sensitive to the variation in time of the signals from the said second means.

1 5. A system according to Claim 1 3 or Claim 14 when dependent on Claim 5 or any of Claims from 6 to 1 2 when dependent on Claim 5, characterised by the fact that the output of the said circuit means is connected to the said second spaced sections of the said second track so that the said fourth electrical signal, in correspondence with the said two levels, controls the rotation and stopping of the said electric motor for positioning the cock in the said open and closed conditions respectively.

1 6. A cock and/or an electronic monitoring circuit utilised in a system for the automatic control of the air temperature introduced into the passenger compartment of a motor vehicle having a heat engine, according to any preceding Claim, 1 7. A system for the automatic control of the temperature of air introduced into the passenger compartment of a vehicle having a heat engine, a cock, and/or an electronic monitoring circuit utilised in the said system, as described with reference to the attached drawings.

1 8. A system substantially as herein described and shown in the accompanying drawings.

1 9. A cock and/or circuit substantially as herein described and shown in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. zone of the said duct leading from the said auxiliary radiator to the said passenger compartment. 1 3. A system according to any of Claims from 8 to 12, characterised by the fact that the said third circuit means comprise comparator means for comparing the said first electrical signal and a second electrical signal provided by the said second means and operable to provide a third electrical signal to frequency modulator means which, via successive circuit means provides a fourth electrical signal at two levels for the control of the said electric motor. 14. A system according to Claim 13, characterised by the fact that to the input of the said frequency modulator means, as well as the said third electrical signal, there is provided a fifth electrical signal coming from detector means sensitive to the variation in time of the signals from the said second means. 1 5. A system according to Claim 1 3 or Claim 14 when dependent on Claim 5 or any of Claims from 6 to 1 2 when dependent on Claim 5, characterised by the fact that the output of the said circuit means is connected to the said second spaced sections of the said second track so that the said fourth electrical signal, in correspondence with the said two levels, controls the rotation and stopping of the said electric motor for positioning the cock in the said open and closed conditions respectively. 1 6. A cock and/or an electronic monitoring circuit utilised in a system for the automatic control of the air temperature introduced into the passenger compartment of a motor vehicle having a heat engine, according to any preceding Claim, 1 7. A system for the automatic control of the temperature of air introduced into the passenger compartment of a vehicle having a heat engine, a cock, and/or an electronic monitoring circuit utilised in the said system, as described with reference to the attached drawings. 1 8. A system substantially as herein described and shown in the accompanying drawings. 1 9. A cock and/or circuit substantially as herein described and shown in the accompanying drawings. engine, the speed of the vehicle and the external temperature (within predetermined limits such as for example - 18"C and + 15"C). Moreover, there is obtained a rapid warming of the passenger compartment of the vehicle starting from a cold starting condition and a rapid reaction to changes in temperature required by the means of the potentiometer 24. Thanks to the succession of phases of opening of the cock 11, each around five seconds, there is no perceptible fluctuation in the temperature in the space around the feet of the occupants of the vehicle.Moreoever, the provision of a motor controlled by an electronic control circuit for regulating the rate of flow of water to the auxiliary radiator presents various advantages such as silence such that this unit 10 can be disposed close to the passenger compartment, and relatively low actuating forces for intercepting the flow of water in the inlet duct 2 leading to the auxiliary radiator 1. Finally, it is clear that the embodiments of the system of the present invention described and illustrated for the cock and the electronic monitoring and control unit can be modified and varied without by this departing from the scope of the invention itself. Among other things, the duct 21 for providing circulation of air around the sensor 1 6 can be eliminated. CLAIMS

1. A system for automatically controlling the temperature of the air introduced into the passenger compartment of a vehicle having a heat engine and including an auxiliary radiator hydraulically connected to a cooling water circuit for the engine, and means for causing the said air which is conveyed into the passenger compartment to traverse the said radiator, characterised by the fact that it includes a cock controlled by an electric motor for regulating the quantity of said water which passes through the said auxiliary radiator, and an electronic monitoring circuit for detecting the temperature of the said air in the said passsenger compartment with respect to a desired set value and for consequently controlling the said electric motor.

2. A system according to Claim 1, characterised by the fact that the said cock is of the type actuated by rotation of the said electric motor.

3. A system according to Claim 2, characterised by the fact that the said cock includes a pair of discs facing one another and disposed transversely with respect to the flow of the said water, one of which is fixed and the other of which is actuatable by rotation of the said motor, each of the said discs being provided with at least one aperture passing therethrough.

4. A system according to Claim 3, characterised by the fact that means for controlling the rotation of the said disc are connected to means operable to stop the said motor and consequently the said disc in at least two positions substantially corresponding to opening and closure of the said cock respectively.

5. A system according to Claim 4, characterised by the fact that the said stop means includes a brush angularly fixed to the said rotation control means and having two arms of different lengths sliding on two printed circuit tracks of different diameters, a first of which is continuous and connected through the said electric motor to an electrical supply terminal at a first polarity, and a second of which is discontinuous and has first sections of relatively greater length connected to a supply terminal at a polarity opposite the said first, and second sections spaced from one another which correspond angularly to the said positions of opening and closure of the said cock and are electrically connected to the said electronic monitoring circuit

6.A system according to Claim 4 or Claim 5 characterised by the fact that it includes means for manually actuating the said means for controlling rotation of the said disc.

7. A system according to one of Claims from 4 to 6, characterised by the fact that the said rotation control means, the said electric motor and the said stop means are contained in a container body mechanically connected to an outer body of the said cock.

8. A system according to any preceding Claim, characterised by the fact that the said electronic monitoring circuit includes first means actuable by a user to generate a first electrical signal in dependence on the said desired set value of temperature for the air in the passenger compartment, second means for detecting the temperature of the air introduced into the passenger compartment; and third circuit means for providing a controlled signal for the said electric motor.

9. A system according to Claim 8, characterised by the fact that the said first means comprise a regulation potentiometer disposed on the dashboard of the said vehicle.

10. A system according to Claim 8 or Claim 9, characterised by the fact that the said second means comprise a first sensor operable to detect the value of the temperature in the passenger compartment, and a second sensor operable to detect the value of the temperature of the air in the conveying duct leading from the said auxiliary radiator to the said passenger compartment.

1 3. A system according to Claim 10, characterised by the fact that it comprises means operable to cause the air to circulate around the said first sensor.

1 2. A system according to Claim 11, characterised by the fact that the said means comprise a duct for withdrawing air from the said passenger compartment, and in the inlet zone of which the said first sensor is disposed, whilst the outlet thereof leads around a nozzle