WO2003081003A2

WO2003081003A2 - Electrically controlled valve for fluid circulation

Info

Publication number: WO2003081003A2
Application number: PCT/FR2003/000951
Authority: WO
Inventors: Matthieu Chanfreau; Gérard Gille
Original assignee: Valeo Thermique Moteur
Priority date: 2002-03-26
Filing date: 2003-03-25
Publication date: 2003-10-02
Also published as: JP2005520974A; WO2003081003A3; FR2837897A1; DE10392436T5; FR2837897B1; AU2003239655A1; AU2003239655A8

Abstract

The invention concerns a valve comprising a valve body or housing (1) closed with a lid (8). It comprises at least one fluid inlet (9) and several fluid outlet pipes (4, 5, 5a) as well as a mobile shutter (10) including at least one fluid passage opening (13). The shutter (10) is driven by the rotor of an electric motor (14) comprising a rotor (15) and a stator (16). The rotor (15) is placed inside the valve body (1) and the stator (15) is located outside the valve body (1). The rotor (15) is separated from the stator (16) so as to be impermeable to the fluid circulating in the valve body (1) by a material layer permeable to the magnetic field. The invention is applicable in particular to cooling circuits of heat engines of motor vehicles.

Description

AT

Electrically operated valve for fluid circulation circuit

The present invention relates to an electrically controlled valve for a fluid circulation circuit, as well as to circuits equipped with such a valve.

It applies in particular to the production of a cooling circuit for a thermal engine of a motor vehicle.

Such a cooling circuit is traversed by a cooling fluid, usually water with an antifreeze added, which circulates in a closed circuit under the action of a circulation pump.

Generally, such a cooling circuit comprises several branches, including a branch which contains a cooling radiator, a branch which constitutes a bypass of the cooling radiator and a branch which contains a radiator called "air heater", used for heating the passenger compartment. .

It is known to use a thermostatic valve which comprises a fluid inlet connected to the engine outlet and two fluid outlets which correspond respectively to the branch containing the cooling radiator and to the branch containing one air heater.

During the cold start of the engine, and as long as the temperature of the coolant does not reach a certain threshold, the valve circulates the coolant in a branch branch by shorting the cooler. As soon as the coolant temperature reaches and exceeds the above threshold, the coolant through the cooling radiator and bypasses the branch branch.

Generally, the cooling fluid circulates permanently in the branch which contains the heating radiator, the heating of the passenger compartment being then obtained by mixing a flow of cold air and a flow of hot air which has swept the heating radiator. It is also known to provide a separate valve on the heating radiator to regulate the flow of cooling fluid passing through it.

The valves generally used for this application are of the type with shutter rotating inside the valve body, as taught for example by US Pat. No. 5,950,576. In known valves of this type, the shutter is driven in its movement rotation by a shaft coupled to an actuator, such as an electric motor of the stepping or continuous type, located outside the valve body. Sealing with the outside of the valve is ensured by a rotary seal surrounding the shaft and pressed between the drive shaft and the valve body. However, repeated rotations of the shutter drive shaft cause, over time, a leakage of the coolant at the passage of the drive shaft in the valve body, which is due to wear of the friction seal on the surfaces with which it is in contact with both the shaft and the valve body. On the other hand, the assembly constituted by the valve body and the actuator has a large bulk.

One of the aims of the invention is to improve the tightness of the rotary shutter valves driven by electric motors in order to prevent any leakage of the coolant. More particularly, the invention aims to provide a control valve of reduced size and excellent robustness, intended for a fluid circulation circuit which, in a preferred embodiment of the invention, constitutes a cooling circuit d 'a motor vehicle heat engine.

In this particular application, it aims to provide a valve which makes it possible to independently manage the flow of cooling fluid in the different branches of the engine cooling circuit, in order to optimize the temperature of the heat engine and the heating of the passenger compartment. .

To this end, the subject of the invention is a control valve for a fluid circulation circuit comprising a valve body or housing closed by a cover, the valve comprising at least one fluid inlet and one or more outlet pipes fluid, as well as a movable shutter having at least one fluid passage opening, the shutter being driven by the rotor of an electric motor comprising a rotor and a stator.

According to a general characteristic of the invention, the rotor is placed inside the valve body and the stator is located outside the valve body. The rotor is separated from the stator in a sealed manner to the fluid circulating in the valve body by a layer of material permeable to the magnetic field.

More particularly, the rotor is encapsulated inside the valve body over all or part of its length inside a cylindrical housing inside the valve body, of substantially constant wall thickness, projecting from the wall of the valve body outward from the valve body in a direction parallel to the axis of rotation rotor. The stator is housed outside the valve body in a second cylindrical housing, surrounding the cylindrical housing of the rotor included in the space formed between a partition concentrically surrounding the wall of the cylindrical housing of the rotor and the outside of the wall of the cylindrical housing of the rotor.

In order to ensure perfect sealing, the walls of the cylindrical housing receiving the rotor and the wall forming the valve body are advantageously molded together so as to form only one piece. Alternatively, the walls of the cylindrical housing are formed by a metal ring attached to the valve body.

According to a first embodiment of the invention, the shutter is constituted by a disc comprising a fluid passage opening allowing a controlled flow of the fluid between the inlet orifice and the fluid outlet pipes when the shutter disc is driven in rotation by the motor. The obturator disc is advantageously formed from a material with a low coefficient of friction and high mechanical resistance, for example ceramic.

According to a second embodiment of the invention, the obturator is constituted by a hollow cylinder comprising at least one fluid passage opening allowing a controlled flow of the fluid between the inlet orifice and the fluid outlet pipes when the shutter is controlled in rotation by the motor.

According to a third embodiment of the invention the shutter is constituted by a truncated solid cylinder. It is thus possible to manage the flow of fluid through the various outputs of the valve, and this as a function of the angular position given to the movable disc or to the cylindrical shutter of the valve.

In this way, the distribution of the fluid can be controlled according to a predefined law.

Such a valve can thus equip a fluid circulation circuit, and in particular a cooling circuit of a motor vehicle engine, to independently manage the coolant flow rates in the various pipes of the circuit.

According to a preferred application of the invention, the circuit is produced in the form of a cooling circuit of a heat engine of a motor vehicle which is traversed by a cooling fluid under the action of a circulation pump. In this application, the control valve is a three-way valve, the fluid inlet of which is connected to a coolant inlet from the engine, and the three fluid outlets of which are respectively connected to the fluid inlets an engine cooling radiator and an air heater for heating the passenger compartment as well as a bypass line for the cooling radiator facilitating the cold start of the engine.

Alternatively, the control valve comprises at least one fluid outlet pipe and at least one fluid inlet, one of the fluid outlets being connected to the inlet of the heat engine. In the detailed description which follows, given by way of example, reference is made to the appended drawings, in which:

- Figures 1 and 2 are perspective views of a first embodiment of a control valve according to the invention;

- Figures 3 and 4 are sectional views respectively in profile and below of the control valve shown in Figure 1;

- Figures 5 to 7 are views respectively from below in profile and from above of the control valve of Figure 1;

- Figure 8 is a perspective view of a second embodiment of a control valve according to the invention;

- Figures 9 and 10 are respectively top and side views of the control valve of Figure 8;

- Figure 11 shows a top view of an alternative embodiment without reducer of the valve produced according to the second embodiment;

- Figure 12 is a view. in section along line XII-XII of Figure 11;

- Figure 13 is a sectional view of a third embodiment of a control valve according to the invention;

- Figure 14 is a sectional view of an alternative embodiment of the control valve of Figure 13; and /

- Figure 15 shows a cooling circuit of a thermal engine of a motor vehicle equipped with a control valve or regulation according to the invention.

5 According to Figures 1 to 7 where the homologous elements have the same references, the control valve shown comprises a valve body 1 or box forming a plug, made of an electrically insulating and non-magnetic material, therefore permeable to the magnetic field, for example polyamide type or

10 polypropylene. The body 10 is internally limited by a bottom wall 2 and a lateral cylindrical wall 3 of axis of revolution XX '. The bottom wall 2 supports the pipes 4 and

5 of fluid outlet oriented respectively along a

- • first direction perpendicular and in a second 5 direction parallel to the bottom wall 2 and opening into the bottom wall by holes 6 and 7. The body 1 is closed by a cover or flange 8 pierced with an opening fluid inlet 9, centered on the axis XX '(Figure 3).

0 A shutter disc 10 movable in rotation about the axis XX ", rests by one of its surfaces on the bottom wall 2 between the bottom wall 2 and the cover 8. The cover 8 rests on bosses 11 and 12 of the shutter disc 10, projecting from the surface opposite that of the shutter disc 10 which rests on the bottom wall 2.

The shutter disc 10 has a fluid passage opening 13 allowing a controlled flow of fluid between the inlet orifice 9 and the fluid outlet pipes 4 and 0 5 when the shutter disc rotates around the axis XX '. According to a preferred embodiment of the invention the shutter disc 10 is made of a material with a low coefficient of friction and a high resistance to wear. Ceramic materials can be used for this, but the use other materials are also possible. The seal between the shutter disc 10 and the outlet orifices of the outlet pipes 4 and 5 is ensured, when the shutter disc 10 closes these orifices, by seals 6a, 6b, 7a surrounding each of the outlet orifices 6 and 7, arranged inside housings of the bottom wall 2.

The obturator disc 10 is rotated about the axis XX 'by an electric motor 14 comprising a rotor 15 and a stator 16 by means of a reduction gear composed of a first toothed wheel 17 driven by the rotor 15 and a second toothed wheel 18 centered around the axis XX 'and disposed on the shutter disc 10 at its periphery. The electric motor 14 is, for example, a stepping type motor or a DC brushless type. According to variant embodiments of the invention, the toothed wheel 18 can be produced either directly by molding the disc 10 or by machining.

The rotor 15 is encapsulated inside the valve body 1 over all or part of its length inside a blind cylindrical housing 19 inside the body 1, of substantially constant wall thickness, projecting from the wall 2 it extends to the outside of the body 1 in a direction parallel to the axis XX '. It is immobilized in translation in the housing 19 by the first toothed wheel 17 which is fixed at its end in an interior space to the valve body 1 comprised between the bottom wall 2, the cover 8 and the toothed wheel 18.

The stator 16 is housed outside the body 1 in a second cylindrical housing 20 surrounding the cylindrical housing 19 in the space between a partition 21 disposed concentrically with the cylindrical wall of the cylindrical housing 19 and the outside of the wall of the cylindrical housing 19. The cylindrical housing 20 is closed by a cover 22 which fits onto the free end edge of the cylindrical wall 21.

This embodiment seals between the stator 16 and the rotor 15, the latter being embedded in the liquid circulating in the valve body 1.

To obtain a perfect seal between the rotor 15 and the stator 16 it is preferable to mold in one piece the bottom 2, the wall 3 and the walls of the cylindrical housings 19 and 20. However, other alternative embodiments are still possible in having suitable seals between these elements.

Also for a good implementation of the invention, particular care will be taken to use a reasonable thickness of material to form the first cylindrical housing 19 so that the air gap between the rotor 15 and the stator 16 is as small as possible in order to obtain sufficient motor torque while consuming the least possible number of amps / revolution in the stator 16.

However, thanks to the reducer formed by the toothed wheels 17 and 18, the torque transmitted by the motor to the shutter disc 10 can be adjusted. Thus it is possible to choose, for example, a motor with low torque and therefore less bulky, by adopting a larger reduction ratio. Furthermore, the reducer makes it possible to reduce the opening resolution of the shutter disc 10 and to make the flow rates in the outlet pipes 4 and 5 more progressive upon opening. A compromise can be found to adapt the opening time and opening resolution of the shutter disc.

In the second embodiment of a flooded rotor valve according to the invention shown in Figures 8 to 12, where the elements homologous to those of Figures 1 to 7 are shown with the same references, the shutter 10 has the form d 'an elongated hollow cylinder movable in rotation about its longitudinal axis XX' inside a valve body 1 of generally cylindrical shape with axis XX 'and delimited by a bottom wall 2.

Unlike the previous embodiment, three fluid outlet pipes 4, 5, 5a open into the valve body 1 at axial heights and at selected angular positions relative to the axis XX '. In the example, the. outlet pipes open radially on the cylindrical wall of the valve body 1 and have different diameters. In Figure 9 two fluid outlet pipes 4 and 5a are arranged in two diametrically opposite directions and an outlet pipe 5 is arranged in a direction perpendicular to the other two.

A flange or cover 8 traversed by a fluid inlet pipe 9 directed into the. direction of the axis XX ′ is fixed to the open end of the cylindrical wall of the valve body 1 opposite the bottom 2. A seal 8a seals between the flange 8 and its part in contact with the body 1.

The shutter cylinder 10 is produced in the form of a hollow cylinder capable of rotating around the axis of rotation XX '. It is crossed in its cylindrical part by orifices 13, 13a of determined dimensions to allow a controlled flow of fluid between the inlet pipe 9 and the outlet pipes 4, 5, 5a.

Similarly to the first embodiment, the shutter cylinder 10 is rotated about the axis XX 'by an electric motor, for example of the stepping type or of the brushless DC type, comprising ^' a rotor 15 and a stator 16. A reduction gear composed of a first toothed wheel 17 and a second toothed wheel 18 centered on the axis XX 'and produced by molding or machining in the thickness of the bottom wall of the shutter cylinder 10, is coupled between the rotor 15 and the shutter cylinder 10.

To seal between the rotor 15 and the stator 16, the rotor 15 is housed, similar to the embodiment of the disc valve described above, inside the valve body 1 over all or part of its length inside a cylindrical housing 19 inside the body 1, of substantially constant wall thickness, projecting from the wall 2 which it extends towards the outside of the body 1 in a direction parallel to the axis XX '. It is immobilized in translation in the housing 19 by the first toothed wheel 17 which is fixed at its end in an interior space to the valve body 1 comprised between the bottom wall 2 of the valve body, the bottom wall of the shutter 10 and the toothed wheel 18.

The stator 16 is housed outside the body 1 in a second cylindrical housing 20 surrounding the cylindrical housing 19 and determined by the space between a partition 21 concentrically surrounding the wall of the cylindrical housing 19 and the outside of the wall of the cylindrical housing 19. The cylindrical housing 20 is closed by a cover 22 which fits on the free end edge of the cylindrical wall 21. As in the previous embodiment, particular care will be taken to use a reasonable thickness of material to form the first cylindrical housing 19 so that the air gap between the rotor 15 and the stator 16 is as small as possible, in order to obtain sufficient engine torque while using as few amps / turn as possible in the stator 16.

Also thanks to the reducer formed by the toothed wheels 17 and 18, the torque transmitted by the motor 14 to the shutter disc 10 can be adjusted. This makes it possible to choose, for example, a motor with low torque and therefore less bulky, by adopting a greater reduction ratio. Furthermore, the reducer makes it possible to reduce the opening resolution of the cylindrical shutter 10 and to make the flow rates in the outlet pipes 4, 5 and 5a more progressive upon opening. As in the example of. previous achievement a compromise can be found to adapt the opening times and the opening resolution of the shutter disc.

It is also possible to carry out the rotation of the cylindrical shutter 10 of the valve described above without reducer in the manner shown in Figures 12 and 13. Of course this embodiment requires the use of a higher engine torque. This requires in this case to offset the motor 14 so as to confuse the axis of rotation of the rotor 15 with the axis XX 'of rotation of the cylindrical shutter 10. In this configuration the bottom wall of the cylindrical shutter 10 comes directly into contact with the bottom wall 2 since the molding of the toothed wheel 18 is eliminated.

In the third embodiment of a flooded rotor valve according to the invention shown in Figure 13, where the elements homologous to those of FIGS. 1 to 12 are represented with the same references, the shutter 10 has the shape of a solid and truncated cylinder, mounted movable in rotation around its longitudinal axis XX 'inside a body of valve 1 of generally cylindrical shape, of axis XX '. and delimited by a bottom wall 2.

As in the previous embodiment, three fluid outlet pipes 4, 5, 5a open into the valve body 1 at axial heights and at selected angular positions relative to the axis XX '. In the example, the outlet pipes open radially on the cylindrical wall 3 of the valve body 1 and have different diameters. In Figure 13 two fluid outlet pipes 4 and 5a are arranged in two diametrically opposite directions, while the outlet pipe 5 (not visible in Figure 12) is arranged in a direction perpendicular to the other two.

A flange or cover 8 traversed by a fluid inlet pipe 9 directed in the direction of the axis XX 'is fixed to the open end of the cylindrical wall of the valve body 1 opposite the bottom 2.

The shutter cylinder 10 has a cut plane 23 forming an acute angle with a plane perpendicular to the axis XX 'and it is surrounded by a sealing ring 24 of generally cylindrical shape which is attached externally.

The shutter cylinder 10 is rotated about the axis XX 'by an electric motor 14, for example of the stepping type or of the brushless DC type, comprising a rotor 15 and a stator 16. The shaft of the motor is parallel to axis XX 'and the shutter is driven by a reducer 25. The reduction gear 25 is composed of a first toothed wheel 26 wedged on the motor shaft and meshing with a second toothed wheel 27 wedged on a shaft 28. This shaft carries a third toothed wheel 29 meshing with a fourth toothed wheel 30 wedged on a shaft 31 which carries the shutter cylinder 10. The reduction gear 25 is housed in a housing 32 formed in the valve body, attached to the bottom wall 2 and closed by a molded block 33 which integrates the motor 14. The molded block 33 also incorporates a printed circuit 34 used to control the motor and having connection pins 35 suitable for being connected to an appropriate supply circuit. A position sensor 36, of the non-contact type, is mounted on the shaft 31 to determine the angular position of the shutter cylinder 10.

To ensure the seal between the rotor 15 and the stator 16, the rotor 15 is housed, similarly to the previous embodiments, inside the valve body 1, and more specifically inside the molded block 33 .

The stator 16 is housed in a second cylindrical housing 20 surrounding the cylindrical housing 19. The walls of the cylindrical housing 19 and of the valve body, in particular of the molded block 33, are molded together to form a single piece.

The valve according to the alternative embodiment of FIG. 14 is very close to that of FIG. 13. It is distinguished by the fact that the walls of the cylindrical housing 19 separating the stator from the rotor are not molded together with the valve body . Indeed, the separation between the stator and the rotor is achieved by a ring 37 attached to the valve body. It is, for example, a thin metal ring, permeable to the magnetic field, and molded into the valve body. The advantage is to be able to further reduce the air gap. Indeed, for equivalent mechanical strength, the thickness of the metal layer may be less than the thickness of the plastic layer.

In the example of FIG. 15, which schematically represents the mounting of a control valve according to the invention in the cooling circuit of a heat engine 38 of a motor vehicle, a control valve 39 according to the invention ensures the distribution of the cooling fluid which circulates under the action of a pump 40. The fluid which is typically water with antifreeze added, is heated by the engine 38 and leaves the latter via an outlet 41 which is connected to the fluid inlet 9 of the valve 39. The outlet pipes 4 and 5 respectively supply via conduits 42 and 43 a cooling radiator 44 and an air heater 45 for heating, of the passenger compartment of the vehicle. After passing through the cooling radiator 44 and the air heater 45, the fluid returns to the pump 40 by return pipes 46 and 47. A pipe 48 directly connects the outlet 5a of the valve to the pump 40.

The valve makes it possible to independently manage the flow of fluid in the aforementioned conduits and thus makes it possible to optimize the temperature of the heat engine 38 and the heating of the passenger compartment.

In particular during the cold start of the engine, it makes it possible to circulate the fluid in the bypass duct 48 without passing through the radiator 44. During this start-up phase it is also possible to pass part of the fluid through the air heater 45, if heating is desired. When the temperature of the fluid has reached or exceeded a predetermined threshold, the connection with the bypass duct 48 is interrupted and the fluid is circulated in the radiator 44, a part of the fluid also being able to circulate through the air heater 45.

In a variant of the circuit of FIG. 15, the valve 39 can be located at the inlet of the heat engine 38. In this case, it comprises at least one fluid outlet pipe and one or more fluid inlet pipes. One of the valve outlet pipes is then connected to the engine inlet.

Of course, the valve of the invention is susceptible of numerous variant embodiments. It is of course not limited to a three-way valve as in the embodiment described above. It is also not limited to an application for the cooling circuit of a thermal engine of a motor vehicle and can be used for other uses in different fields.

Claims

claims

1. Control valve for a fluid circulation circuit comprising a valve body or housing (1) closed by a cover (8), the valve comprising at least one fluid inlet (9) and one or more outlet pipes from fluid (4, 5; 5a) as well as a movable shutter (10) comprising at least one fluid passage opening (13), the shutter (10) being driven around an axis (XX ') by the rotor an electric motor (14) comprising a rotor (15) and a stator (16),

characterized in that the rotor (15) is placed inside the valve body (1) and in that the stator (15) is located outside the valve body (1), the rotor (15) being separated from the stator (16) in a sealed manner to the fluid flowing in the valve body (1) by a layer of material permeable to the magnetic field.

2. Valve according to claim 1, characterized in that the rotor (15) is hooded inside the valve body (1) over all or part of its length inside a cylindrical housing (19) inside to the valve body (1), of substantially constant wall thickness, projecting from the wall (2) of the valve body which it extends towards the outside of the valve body (1) in a direction parallel to the axis (XX ') of rotation of the rotor (15).

3. Valve according to claim 2, characterized in that the walls of the cylindrical housing (19) and the valve body (1) are molded together to form a single piece.

4. Valve according to claim 2, characterized in that the walls of the cylindrical housing (19) are formed by a metal ring (37) attached to the valve body (1).

5. Valve according to one of claims 1 to 4, characterized in that the stator (16) is housed outside the valve body (1) in a second cylindrical housing (20) surrounding the cylindrical housing (19) of the rotor (15), included in the space formed between a partition (21) concentrically surrounding the wall of the cylindrical housing (19) of the rotor (15) and the outside of the wall of the cylindrical housing (19) of the rotor (15 ).

6. Valve according to one of claims 1 to 5, characterized in that the motor (14) is a stepper motor.

7. Valve according to one of claims 1 to 5, characterized in that the motor (14) is a brushless DC motor.

8. Valve according to one of claims 1 to 7, characterized in that the shutter (10) is driven by the motor through a reduction gear (17, 18; 25).

9. Valve according to one of claims 1 to 8, characterized in that the shutter is constituted by a disc (10) having an opening (13) for passage of fluid allowing a controlled flow of the fluid between the orifice of inlet (9) and fluid outlet pipes (4, 5) when the obturating disc is rotated by the motor (14), said disc (10) being coupled to the motor (14) by a reduction gear composed of a first toothed wheel (17) fixed to one end of the rotor (15) not covered by the wall of the housing (19) of the rotor (15) and of a second toothed wheel (18) located at the periphery of the shutter disc (10) and meshing on the first toothed wheel (17).

10. Valve according to claim 9, characterized in that the disc of the shutter (10) is made of a material with low coefficient of friction and high mechanical resistance.

11. Valve according to claim 10, characterized in that the disc of the shutter (10) is ceramic.

12. Valve according to one of claims 1 to 8, characterized in that the shutter (10) consists of a hollow cylinder comprising at least one fluid passage opening (13, 13a) allowing a controlled flow of fluid between the inlet orifice (9) and fluid outlet pipes (4, 5, 5a) when the shutter (10) is rotated by the motor (14), the said shutter (10) being coupled to the motor (14) by a reducer composed of a first toothed wheel (17) fixed to one end of the rotor (15) not covered by the wall of the housing (19) of the rotor (15), and of a second toothed wheel ( 18) located on the bottom wall of the cylindrical shutter (10) and meshing on the first toothed wheel (17).

13. Valve according to one of claims 1 to 8, characterized in that the shutter (10) consists of a hollow cylinder comprising at least one opening for passage of fluid (13, 13a) allowing a controlled flow of the fluid between the inlet orifice (9) and fluid outlet pipes (4, 5, 5a) when the shutter (10) is rotated by the motor (14), the said shutter (10) being coupled to the motor (14), said shutter being directly coupled to the rotor (15) of the motor (14).

14. Valve according to one of claims 1 to 8, characterized in that the shutter (10) consists of a solid truncated cylinder.

15. Fluid circulation circuit, characterized in that it comprises a control valve according to one of claims 1 to 14, whose fluid inlet (9) is connected to a source of fluid and whose outlets of fluid (4, 5, 5a) are respectively connected to conduits of the circuit.

16. The circuit as claimed in claim 15, characterized in that it is produced in the form of a cooling circuit of a heat engine (38) of a motor vehicle, which is traversed by a cooling fluid under the action of '' a circulation pump (40), and in that the control valve (39) is a three-way outlet valve, the fluid inlet (9) of which is connected to a coolant inlet (41) coming from the engine (38), and two of the fluid outlet pipes (4, 5) of which are connected respectively to a fluid inlet of a cooling radiator (44) and to a fluid inlet of an air heater ( 45) for heating the passenger compartment of the vehicle and whose third fluid outlet (5a) of the bypass circuit is connected to a bypass line (48) of the cooling radiator (44).

17. Circuit according to claim 15, characterized in that it is produced in the form of a cooling circuit of a heat engine (38) of a motor vehicle, which is traversed by a cooling fluid under the action of '' a circulation pump (25), and in that the control valve (39) comprises at least one fluid outlet pipe (4, 5, 5a) and at least one fluid inlet (9), one fluid outlets being connected to the inlet of the heat engine (38).