DEVICE FOR A VEHICLE INCORPORATING SUCH A VALVE

TECHNICAL FIELD

[0001] The invention relates to a non-return valve, to a cooling circuit and to a cooling device for a vehicle comprising such a valve.

BACKGROUND

[0002] Patent document FR-A1-2 913 374 describes a motor vehicle cooling circuit.

[0003] Conventionally, a vehicle cooling circuit is a closed circuit comprising various pipes extending from the engine and from the water pump of the vehicle, defining various loops. One loop for example extends near the passenger compartment of the vehicle in order to heat the latter. Other loops comprise a thermostat, a radiator, a gas purging tank etc.

[0004] A vehicle cooling device may comprise one or more cooling circuits. It may for example comprise a first cooling circuit known as a high-temperature cooling circuit, at at least 90°C for example, and a second cooling circuit known as a low-temperature cooling circuit, of the order of 60-70°C for example. This second circuit can be used to cool batteries of an electric vehicle for example.

[0005] There are a number of possible architectures for this device.

[0006] In a first scenario, the two circuits may be independent and may each comprise a gas purging tank. The device is then equipped with two independent gas purging tanks.

[0007] In another scenario, part of each the two circuits is common to both. It is advantageous to have the gas purging tank common so that the device comprises just one of these. This saves space and also makes it easier to fill the circuits with fluid because the feed port of the gas purging tank can be used to fill both circuits. However, in practice, the tank is actually used only for purging gas from the first circuit. The second circuit is connected by a loop to the fluid outlet of the tank. The tank acts as a gas-purging tank for the second circuit only while it is being filled. In operation, the tank is used only as an expansion tank for the second circuit if the temperature of the fluid contained in this circuit rises.

[0008] In yet another scenario, which is a preferred scenario, the gas-purging tank is connected to both circuits in such a way as to be able during operation to perform the gas- purging function for each of these circuits. In that case, the second circuit is connected by loops to the fluid inlet and outlet of the tank, the loop connected to the fluid outlet needing to be fitted on the one hand with a non-return or check valve so as to allow the filling of the second circuit and prevent the fluid contained in this second circuit from escaping into the first circuit and, on the other hand, with a shut-off valve (an "on/off valve) which is made to close when the temperature of the fluid in the second circuit reaches a predetermined threshold (for example 60-70°C).

[0009] However, juxtaposing two valves on the loop leads to problems particularly of bulk.

[0010] The present invention proposes a solution to this problem which is

straightforward, effective and economical.

SUMMARY OF THE INVENTION

[0011] The invention thus proposes a non-return valve, in particular for a motor vehicle, comprising a fixed casing comprising an internal duct extending between a fluid inlet and a fluid outlet and a member that is mobile between a first position of blocking of said duct and a second position of opening of said duct, said mobile member being configured to be displaced from said first position to said second position when a fluid flow rate above a predetermined threshold enters into said duct via said inlet, and to be displaced from said second position to said first position when said flow rate is below said threshold, characterized in that it further comprises means in particular controlled for immobilizing said member in said second position.

[0012] The invention thus proposes combining the functions of the non-return and shut- off valves of the current art into a single valve which thus has a dual function. It on the one hand acts as a conventional non-return valve and is also configured to perform a function of keeping the valve in the closed position. The invention is thus advantageous in terms of compactness and therefore of space saving.

[0013] The valve according to the invention may comprise one or more of the following features, considered in isolation from one another or in combination with one another:

- the immobilizing means are electric or pneumatic immobilizing means;

- said mobile member comprises a ferromagnetic body, said immobilizing means comprising at least one electric coil at least partly surrounding said body;

- said body has an elongate form and is mounted to slide along its axis of elongation inside said casing;

- said casing comprises at least one internal cylindrical surface for guiding said body along said axis of elongation;

- said casing comprises a first cylindrical wall comprising said internal cylindrical surface and an external cylindrical surface on which said at least one coil is mounted;

- said at least one coil is surrounded by a second cylindrical wall, which is formed of a single piece with said first cylindrical wall or added thereto;

- said at least one coil is mounted on a support sleeve, itself mounted on said first wall;

- said casing comprises a part equipped with electrical connection means for said at least one coil;

- said equipped part is formed of a single piece with said support sleeve or said second cylindrical wall;

- said body is solid cylindrical or tubular and externally or internally defines a flow path for said fluid;

- said mobile member comprises a head configured to collaborate in bearing and sealing with an internal annular seat of said casing when said member is in its first position;

- said head at least partially has an spherical or ovoid shape;

- said mobile member is urged toward its second position by return means such as a compression spring, for example a helical compression spring; - the return means are configured to be deformed, for example by compression, by the application of a force of less than 1 N, and for example of between 0.1 and 0.5 N;

- the return means are configured to exert a return force of less than 1 N, and for example of between 0.1 and 0.5 N;

- said return means are mounted coaxially inside or outside said body;

- said casing comprises an internal chamber configured to be connected to air supply and/or air evacuation means;

- said mobile member comprises a first body of elongate form and mounted to slide along its axis of elongation inside said casing, at least one portion of said first body extending into said chamber;

- an elastically deformable membrane is mounted in said chamber and is fixed respectively to said casing and to said portion, said membrane being configured to be deformed following an activation of said supply and/or evacuation means to drive or follow said first body from its second position to its first position;

- said membrane has an annular shape and comprises an internal peripheral edge fixed to said portion and an external peripheral edge fixed to said casing;

- said portion comprises an annular surface against which the membrane can bear and be guided as it deforms;

- said mobile member comprises a second body that is independent of said first body and coaxial thereto, said second body being mounted to slide along said axis of elongation inside said casing between said first and second positions;

- said first and second bodies are stressed apart from one another by return means such as a compression spring;

- said threshold is zero or near-zero; and

- said inlets and outlets are substantially aligned or at right angles; as an alternative, they are inclined by a given angle.

[0014] The present invention also relates to a cooling circuit, in particular a low- temperature cooling circuit, for a vehicle, comprising at least one non-return valve as described hereinabove. [0015] The circuit may comprise a loop comprising said non-return valve, a water pump and a gas purging and expansion tank.

[0016] The present invention also relates to a cooling device for a vehicle, comprising a low-temperature cooling circuit as described hereinabove, a high-temperature cooling circuit, and a tank configured to ensure gas purging and expansion functions for said circuits.

[0017] Advantageously, said tank comprises a fluid outlet connected to said high- temperature cooling circuit, this outlet also being connected to said non-return valve of said low-temperature cooling circuit.

BRIEF DESCRIPTION OF THE FIGURES

[0018] The invention will be better understood and further details, features and advantages of the present invention will become more clearly apparent from reading the following description, given by way of nonlimiting example and with reference to the attached drawings, in which:

[0019] FIG. 1 is a highly schematic view of a cooling device particularly for a vehicle;

[0020] FIG. 2 is a schematic view in axial section of a first embodiment of a non-return valve according to the invention, here in the closed position;

[0021] FIG. 3 is a schematic view in axial section of the valve of FIG. 2, here in the open position;

[0022] FIG. 4 is a schematic view in section on the line IV-IV of FIG. 3;

[0023] FIG. 5 is a schematic view in axial section of a second embodiment of a nonreturn valve according to the invention, here in the closed position;

[0024] FIG. 6 is a schematic view in axial section of the valve of FIG. 5, here in the open position;

[0025] FIG. 7 is a schematic view in section on the line VII- VII of FIG. 6; [0026] FIG. 8 is a schematic view in axial section of a third embodiment of a non-return valve according to the invention, here in the closed position;

[0027] FIG. 9 is a schematic view in axial section of the valve of FIG. 8, here in the open position;

[0028] FIG. 10 is a schematic view in axial section of the valve of FIG. 8, here in the blocked position; and

[0029] FIG. 11 is another partial schematic view in axial section of the valve of FIG. 8 and shows an air intake duct.

DETAILED DESCRIPTION

[0030] FIG. 1 schematically depicts a cooling device 10 for a motor vehicle, this device 10 comprising two interconnected cooling circuits, a main cooling circuit 12 referred as the high-temperature cooling circuit (for example at at least 90°C) and a secondary cooling circuit 14, referred to as a low-temperature cooling circuit (for example of the order of 60- 70°C).

[0031] The main circuit 12 is well known to those skilled in the art and will not be described in detail. It is depicted schematically as a rectangle in dotted line and comprises a fluid inlet 16 connected to a fluid outlet 18 of a gas-purging tank 20, and a fluid outlet 22 connected to a fluid inlet 24 of the tank 20.

[0032] The secondary circuit 14 comprises a water pump 26 a fluid inlet 28 of which is connected by a pipe 30 to the fluid outlet 18 of the tank 20. The fluid outlet 32 of the water pump 26 is connected to a number of parallel loops for cooling elements 34 of the vehicle, these loops being connected to the fluid inlet 24 of the tank 20. These loops are also connected to an inlet of a thermostat 36 which, according to the temperature of the fluid in the circuit 14, either allows the fluid to pass through a radiator 38 or bypasses this radiator and returns to the water pump 26. The outlet of the radiator is also connected to the inlet 28 of the water pump 26.

[0033] The pipe 30 here comprises two independent valves, a non-return valve 40 and a shut-off valve 42. The non-return valve 40 opens as soon as the force of the liquid exceeds that of the spring, for example during the phase of filling the circuits 12 and 14, which is done via the outlet 18 of the tank 20. This valve 40 isolates the circuit 14 and prevents fluid from passing from the circuit 12 toward the circuit 14. In the same way, a non-return valve 44 is provided at the outlet 22 of the circuit 12 to isolate this and prevent fluid from passing from the circuit 12 toward the circuit 14.

[0034] The shut-off valve 42 is opened when the circuit 14 increases in temperature so that, in combination with the valves 40 and 44, the tank 20 performs a gas-purging and expansion function, and is then closed when the fluid of the circuit 14 reaches a certain temperature. The circuit 14 is then shut off, the law of conservation of flow being such that, despite there being no valve in the pipe connecting the circuit 14 to the inlet 24 of the tank, the closing of the valve 42 is enough to isolate the circuit 14 from the rest of the device.

[0035] The invention proposes combining the functions of the valves 40, 42 into one and the same valve.

[0036] FIGS. 2 to 4 depict a first embodiment of a non-return valve 50 according to the invention.

[0037] The valve 50 comprises a casing 52, for example made of plastic, which defines an internal duct for the circulation of a fluid from a fluid inlet 54 to a fluid outlet 56.

[0038] In the example depicted, the internal duct has a rectilinear and elongate overall form, its inlet 54 being situated to the left in the drawing and its outlet 56 to the right. The axis of elongation of the duct and of the casing 52 is denoted A.

[0039] The casing 52 is fixed and intended to be fixed to an element of the vehicle. It comprises a member 58 that is mobile inside the duct, between a first position of shutting of the duct, depicted in FIG. 2, and a second position of opening of the duct, depicted in FIG. 3.

[0040] The member 58 is here mounted mobile in a substantially cylindrical cavity 60 of the duct, coaxial with the fluid inlet and outlet 54, 56. The casing 52 here is formed by two tubular portions 52a, 52b fixed coaxially to one another. Each portion 52a, 52b here comprises a first cylindrical wall 52aa, 52ba internally defining the fluid inlet or outlet 54, 56 and a second cylindrical wall 52ab, 52bb internally defining a portion of the cavity 60. [0041] In the example depicted, the second wall 52ab, 52bb of a section 52a, 52b has a larger diameter than the first wall 52aa, 52ba of this portion. Moreover, the second wall 52bb of the portion 52b has a diameter, particularly an inside diameter, slightly greater than that of the second wall 52ab of the other portion 52a.

[0042] The wall 52ab of the portion 52a comprises, at its opposite axial end to the wall 52aa, a radially external annular flange 52ac pressed axially against a similar external annular flange 52bc of the wall 52bb of the portion 52b. These flanges 52ac, 52bc may be joined together by welding.

[0043] The casing 52 comprises, inside the duct and, more specifically, the cavity 60, a coaxial finger 62. The finger 62 is connected by spacers 64 to the casing, and more specifically to the zone where the walls 52ba, 52bb of the portion 52b meet. The finger 62 extends axially from this zone as far as more or less half of the axial dimension or length of the wall 52bb of this portion 52b. The spacers 64 in this instance are three in number (FIG. 4). They extend substantially radially with respect to the axis A and are uniformly distributed about this axis A. The spacers 64, the finger 62 and the portion 52b may be produced as a single piece as in the example depicted.

[0044] The mobile member 58 here comprises two elements, a tubular body 58a and a head 58b. The body 58a is defined by a tubular cylindrical wall of axis A. The body 58a is mobile in sliding along the axis A and is centered and guided inside the cavity 60, through cooperation between its cylindrical external surface and the internal cylindrical surface of the wall 52bb of the portion 52b.

[0045] The body 58a extends over 60 to 90% of the length of the cavity 60 in the example depicted. The free end of the body 58a, which end is situated on the side of the inlet 54 of the duct, is fixed to the head 58b.

[0046] The head 58b here has an ovoid overall shape and comprises a free end, situated on the side of the inlet 54, shaped as a portion of a sphere. This free end is intended to collaborate by bearing in a sealed manner with an internal annular seat 66 here situated in the zone where the walls 52aa, 52ab of the portion 52a meet. [0047] The opposite end of the head 58b, which is therefore situated on the side of the outlet 56, comprises a substantially cylindrical housing 68 aligned with the axis A and accepting one axial end of a return spring 70. The opposite axial end of the spring 70 is housed in a cylindrical housing 72 of the axial end of the finger 62 which is situated on the side of the inlet 54. The return spring 70 here is a compression helical spring of axis A.

[0048] The head 58b comprises radial protrusions 58bb for fixing to the body 58a. The external radial ends of the protrusions 58bb are situated on a circumference of a diameter substantially equal to the internal diameter of the wall 52ab of the portion 52a. The head 58b is thus centered and guided in translational movement along the axis A by

collaboration between its protrusions 58bb and the internal cylindrical surface of this wall 52ab.

[0049] As can be seen from the drawings, the member 58 is mobile:

- from the position of closure of the valve 50 of FIG. 2, in which position it is situated at one axial end, in this instance the left-hand axial end, of the cavity 60, the spring 70 axially urging the head 58b and the body 58a axially toward this end and the head 58b bearing sealingly against the seat 66,

- as far as the open position of FIG. 3, in which position the member 58 is situated at the opposite axial end, in this instance the right-hand axial end, of the cavity 60, the spring 70 being loaded axially and the head 58b being situated some distance from the seat 66.

[0050] In the absence of a flow of fluid in the duct, the valve 50 is closed. The compression spring 70 actually urges the head 58b against the seat 66. When a fluid enters the valve 50 via its inlet 54, it applies a force to the head 58b. When the fluid flow rate is above a certain threshold, the force applied to the head 58b is such that it exceeds the return force of the spring 70 which is axially compressed. The member 58 therefore moves from its first position into its second position. When the fluid flow rate drops below the threshold, the return force of the spring becomes higher than the force exerted by the fluid on the head, which moves from its second into its first position. When a fluid enters the valve via its outlet, it is blocked by the head 58b which is bearing sealingly against its seat 66. [0051] With the exception of its protrusions 58bb, the head 58b has a maximum outside diameter that is smaller than the inside diameter of the wall 52ab and of the cavity 60 so that fluid can flow into the cavity 60, between the head 58b and the casing 52 when the head is not bearing sealingly against the seat 66.

[0052] At the valve inlet 54, the flow path for the passage of fluid has a circular cross section. At the level of the head 58b of the member 58, the passage flow path upstream has an annular cross section, at the level of the protrusions 58bb a segmented cross section and then again an annular cross section downstream of these protrusions. Such is also the case at the level of the finger 62 where the flow path extends between the finger 62 and the tubular body 58a. This flow path is then segmented at the level of the spacers 64 into three angular segments (FIG. 4). Downstream of the spacers 64 the flow path once again is circular in cross-sectional shape.

[0053] The valve 50 further comprises means 80, in this instance electric means, for immobilizing the member 58 at least in its first position, namely its closed position.

[0054] The means 80 here comprise at least one electric coil 82 which is mounted coaxially on the wall 52bb of the portion 52b. In the example depicted, the coil 82 extends over substantially the entire length of this wall 52bb, between the flange 52bc of the portion 52b and its region where the walls 52ba, 52bb meet.

[0055] The coil 82 here is mounted on a tubular support sleeve 84, which is itself engaged on the wall 52bb. This sleeve 84 in longitudinal cross section is substantially U- shaped and may be used to prepare the coil and in particular for winding the conducting wire or wires thereof. The sleeve 84 comprises at one axial end, situated on the side of the inlet 54, an external radial flange 84a pressed against the flange 52bc of the portion 52b, and an external radial flange 84b at the opposite end.

[0056] The coil 82 is surrounded by a cylindrical wall 86 of an annular cover 88 connected to the casing 52. The end of the wall 86, situated on the side of the inlet 54 of the valve, is pressed against the flange 52bc of the portion 52b and fixed to this flange, for example by welding or by bonding. The opposite end of the wall 86 is connected to the external periphery of an internal annular flange 90 of the cover 88, the internal periphery of which bears against and can be fixed to the casing 52, for example by welding or bonding. The support sleeve 84 may be held clamped axially between the flange 52bc of the portion 52b and the flange 90 of the cover 88.

[0057] The cover 88 comprises means of electrically connecting the coil 82 to electrical supply and control means (not depicted). As mentioned in the foregoing, when the temperature of the fluid in the circuit 14 comprising the valve 50 reaches a predetermined threshold, for example 60 or 70°C, the coil 82 is electrically powered and generates a magnetic field inside the duct. The body 58a, which in this instance is made of a ferromagnetic material, is then urged by the magnetic field into the position of closure of the valve (FIG. 2). The member 58 is therefore blocked in this closed position as long as the coil 82 is powered.

[0058] FIGS. 5 to 7 depict a second embodiment of a non-return valve 150 according to the invention.

[0059] The valve 150 comprises a casing 152, for example made of plastic, which defines an internal duct for the circulation of a fluid from a fluid inlet 154 as far as a fluid outlet 156.

[0060] In the example depicted, the internal duct has the overall form of an L. The inlet 154 has an axis A and the outlet has an axis B. These axes A, B are substantially perpendicular.

[0061] The casing 152 is fixed and intended to be fixed to an element of the vehicle. It comprises a member 158 that is mobile inside the duct, between a first position of blocking of the duct, depicted in FIG. 5, and a second position of opening of the duct, depicted in FIG. 6.

[0062] The member 158 is in this instance mounted mobile in a substantially cylindrical cavity 160 of the duct, coaxial with the inlet 154. The casing 152 is formed here by two tubular sections 152a, 152b fixed to one another.

[0063] The section 152a comprises a first cylindrical wall 152aa of axis A and internally defining the fluid inlet 154, and a second cylindrical wall 152bb of axis A and internally defining a portion of the cavity 160. [0064] The section 152b comprises a first cylindrical wall 152ba of axis B and internally defining the fluid outlet 154, and connected at right angles to a second substantially cylindrical wall 152bb of axis A. This second wall 152bb comprises a front or upstream first part 152bba partially forming the cavity 160 and an elbow 15bbb connecting this cavity 160 to the outlet 156. The second wall 152bb further comprises a rear or

downstream second part 152bbc of axis A and comprising two coaxial cylindrical walls, these respectively being a radially internal wall 152bbcl and a radially external wall 152bbc2.

[0065] In the example depicted, the second wall 152ab of the section 152a has a larger diameter than the first wall 152aa of this section. Moreover, the wall 152aa and the part 152bbc have substantially the same diameter and the upstream end of the part 152bba has an internal diameter substantially equal to that of the wall 152ab.

[0066] The wall 152ab of the section 152a comprises, at its opposite axial end to the wall 152aa, a radially external annular flange 152ac pressed axially against a similar external annular flange 152bc of the wall 152bb of the section 152b. These flanges 152ac, 152bc may be fixed together by welding.

[0067] The mobile member 158 here comprises two elements, a cylindrical body 158a and a head 158b. The body 158a is mobile in sliding along the axis A and is centered and guided inside the cavity 160 through collaboration between its external cylindrical surface and the internal cylindrical surface of the wall 152bbcl . This wall 152bbcl here defines a cylindrical housing for guiding the body 158, which is closed at its opposite axial end to the inlet 154 by a radial wall 161. The free end of the body 158a, situated on the same side as the inlet 154 of the duct, is fixed to the head 158b.

[0068] The head 158b here is of ovoid overall form and comprises a free end, situated on the same side as the inlet 154, shaped as a portion of a sphere. This free end is intended to collaborate with an internal annular seat 166 by pressing sealingly against this seat which is here situated in the zone where the walls 152aa, 152ab of the section 152a meet.

[0069] The opposite end of the head 158b, which is therefore situated on the same side as the outlet 156, comprises a substantially cylindrical housing 168 of axis A in which one axial end of the body 158a is housed. A return spring 170 is mounted around the body 158a and bears axially against this end of the head 158b. The other end of the spring 170 bears axially against a radial end face of the wall 152bbcl . The return spring 170 here is a helical compression spring of axis A.

[0070] The head 158b comprises radial projections 158bb. The external radial ends of the projections 158bb are situated on a circumference of diameter substantially equal to the internal diameter of the wall 152ab of the section 152a. The head 158b is thus centered and translationally guided along the axis A through collaboration between its projections 158bb and the internal cylindrical surface of this wall 152ab.

[0071] As can be seen in the drawings, the member 158 is mobile:

- from the position of closure of the valve 150 in FIG. 5, in which position it is situated at one axial end, in this instance the left-hand end, of the cavity 160, the spring 170 axially urging the head 158b and the body 158a axially toward this end and the head 158b bearing sealingly against the seat 166,

- as far as the position of opening of FIG. 6, in which position the member 158 is situated at the opposite axial end, in this instance the right-hand end, of the cavity 160, the spring 170 being stressed axially and the head 158b being situated some distance from the seat 166.

[0072] In the absence of circulation of fluid in the duct, the valve 150 is closed. The compression spring 170 effectively urges the head 158b against the seat 166. When a fluid enters the valve 150 via the inlet 154 thereof, it applies a force to the head 158b. When the fluid flow rate exceeds a certain threshold, the force applied to the head 158b is such that it is greater than the return force of the spring 170 which is axially compressed. The member 158 therefore moves from its first into its second position. When the fluid flow rate drops below the threshold, the return force of the spring becomes greater than the force exerted by the fluid on the head, which moves from its second into its first position. When a fluid enters the valve via its outlet, it is blocked by the head 158b which is pressing sealingly against its seat 166.

[0073] With the exception of its protrusions 158bb, the head 158b has a maximum external diameter that is smaller than the internal diameter of the wall 152ab and of the cavity 160 so that fluid can flow inside the cavity 160, between the head 158b and the casing 152 when the head 158b is not pressed sealingly against the seat 166.

[0074] At the valve inlet 154, the fluid passage flow path has a circular cross section. At the head 158b of the member 158, the passage flow path has an annular cross section upstream, a sectorized cross section in the region of the protrusions 158bb, and then an annular cross section again downstream of these protrusions. Each sector of flow path extends between two protrusions of the head 158b. Downstream of the spacers, the flow path once again has a circular cross-sectional form.

[0075] The valve 150 further comprises means 180, in this instance electric means, of immobilizing the member 158 at least in its first position, which is to say its closed position.

[0076] The means 180 here comprise at least one electric coil 182 which is mounted coaxially on the wall 152bbcl and more precisely in the annular space extending between the walls 152bbcl and 152bbc2. In the example depicted, the coil 182 extends over substantially the entire length of the wall 152bbcl .

[0077] The coil 182 here is mounted on a tubular support sleeve 184, which is itself engaged on the wall 152bbcl . This sleeve 184 in longitudinal cross section is substantially U-shaped and can be used for preparing the coil and in particular for winding its conducting wire or wires. The sleeve 184 at one axial end, situated on the same side as the inlet 154, comprises an external radial flange 184a pressed against a cylindrical bearing surface 185 of the wall 152bbcl, and an external radial flange 184b at the opposite end.

[0078] The coil 182 is surrounded by the cylindrical wall 152bbc2 which may bear against the flanges 184a, 184b of the sleeve 184. In the example depicted, the sleeve 184 is formed as a single piece with an annular cover 188 attached to the casing 152. The cover 188 comprises a radial wall, which in this instance coincides with the flange 184b, and which is engaged in the free end of the wall 152bbc2. This radial wall comprises a central orifice 192 through which there passes a finger 194 projecting from the casing, extending in the downstream direction along the axis A from the radial wall 161. This finger 194 is crimped to immobilize the cover 188 on the casing 152. The support sleeve 184 is thus kept clamped axially between the bearing surface 185 and the crimped finger 194. [0079] The cover 188 comprises means of electrically connecting the coil 182 to electrical control and power supply means (not depicted). As mentioned in the foregoing, when the temperature of the fluid in the circuit 14 comprising the valve 150 reaches a predetermined threshold, for example 160 or 170°C, the coil 182 is electrically powered and generates a magnetic field inside the duct. The body 158a, which in this instance is made of a ferromagnetic material, is then urged by the magnetic field into the position of closure of the valve (FIG. 6). The member 158 is then blocked in this closed position as long as the coil 182 is powered.

[0080] FIGS. 8 to 11 depict a third embodiment of a non-return valve 250 according to the invention.

[0081] The valve 250 comprises a casing 252, for example made of plastic material, which defines an internal duct for the circulation of a fluid from a fluid inlet 254 as far as a fluid outlet 256.

[0082] In the example depicted, the internal duct has the overall form of an L. The inlet 254 has an axis A and the outlet has an axis B. These axes A, B are substantially perpendicular.

[0083] The casing 252 is fixed and intended to be fixed to an element of the vehicle. It comprises a member 258 mobile inside the duct between a first position of blocking of the duct, depicted in FIG. 5, and a second position of opening of the duct, depicted in FIG. 6.

[0084] The member 258 here is mounted mobile in a substantially cylindrical cavity 260 of the duct, coaxial with the inlet 254. The casing 252 here is formed of two tubular sections 252a, 252b fixed to one another.

[0085] The section 252a comprises a first cylindrical wall 252aa of axis A and internally defining the fluid inlet 254, and a second cylindrical wall 252ab of axis A and internally defining a portion of the cavity 260.

[0086] The section 252b comprises a first cylindrical wall 252ba of axis B and internally defining the fluid outlet 254, and connected at right angles to a substantially cylindrical second wall 252bb of axis A. This second wall 252bb comprises a forward or upstream first part 252bba partially forming the cavity 260, and an elbow 252bb connecting this cavity 260 to the outlet 256.

[0087] In the example depicted, the second wall 252ab of the section 252a has a larger diameter than the first wall 252aa of this section. Moreover, the wall 252aa and the wall 252bb have substantially the same diameter and the upstream end of the part 252bba has an internal diameter substantially equal to that of the wall 252ab.

[0088] The wall 252ab of the section 252a comprises at its opposite axial end to the wall 252aa a radially external annular flange 252ac pressed axially against a similar external annular flange 252bc of the wall 252bb of the section 252b. These flanges 252ac, 252bc may be fixed together by welding.

[0089] The mobile member 258 here comprises three elements, a cylindrical body 258a made in two parts 258al, 258a2, and a head 258b. The body 258a is mobile in sliding along the axis A and is centered and guided inside the cavity 260 by collaboration between its external cylindrical surface and an internal cylindrical surface of axis A of the wall 252bb.

[0090] The head 252b here is of ovoid overall shape and comprises a free end, situated on the same side as the inlet 254, shaped as a portion of a sphere. This free end is intended to collaborate with an internal annular seat 266 by pressing sealingly against this seat which is here situated in the zone where the walls 252aa, 252ab of the section 252a meet.

[0091] The parts 258al, 258a2 of the body are coaxial and arranged one behind the other along the axis A. They each have a portion engaged slidingly in the wall 252bb.

[0092] The part 258al of the body is fixed to the head 258b and formed as a single piece with the head 258b in the example depicted. This part 258al at its opposite end from the head 258b comprises a substantially cylindrical housing 268 to house an axial end of a return spring 270 of axis A. The other end of the spring 270 is housed in a cylindrical housing 272 opposite the other part 258a2 of the body. The return spring 270 here is a helical compression spring of axis A.

[0093] The head 258b comprises radial projections 258bb. The external radial ends of the projections 258bb are situated on a circumference of diameter substantially equal to the internal diameter of the wall 252ab of the section 252a. The head 258b is thus centered and translationally guided along the axis A by collaboration between its protrusions 258bb and the internal cylindrical surface of this wall 252ab.

[0094] As can be seen from the drawings, the member 258 is mobile:

- from the position of closure of the valve 250 in FIG. 5, in which position it is situated at one axial end, in this case the right-hand end, of the cavity 260, the spring 270 axially urging the head 258b and the body 258a axially toward this end and the head 258b bearing sealingly against the seat 266,

- as far as the position of opening in FIG. 6, in which position the member 258 is situated at the opposite axial end, in this case the left-hand end, of the cavity 260, the spring 270 being stressed axially and the head 258b being situated some distance away from the seat 266.

[0095] In the absence of circulation of fluid in the duct, the valve 250 is closed. The compression spring 270 in fact urges the head 258b against the seat. When a fluid enters the valve 250 via the inlet 254 thereof it applies a force to the head 258b. When the fluid flow rate is greater than a certain threshold, the force applied to the head 258b is such that it is greater than the return force of the spring 270 which is axially compressed. The member 258 then moves from its first into its second position. When the fluid flow rate drops below the threshold, the return force of the spring becomes higher than the force exerted by the fluid on the head, which moves from its second into its first position. When a fluid enters the valve via its outlet, it is blocked by the head 258b which is bearing sealingly against its seat 266.

[0096] With the exception of its projections 258bb, the head 258b has a maximum external diameter smaller than the internal diameter of the wall 252ab and of the cavity 260 so that fluid can flow inside the cavity 260 between the head 258b and the casing 252 when the head 258b is not pressing sealingly against the seat 266.

[0097] At the inlet 254 of the valve, the fluid passage flow path has a circular cross section. In the region of the head 258b of the member 258 the passage flow path has an annular cross section upstream, a sectorized cross section in the region of the protrusions 258bb, then once again an annular cross section downstream of these protrusions. Each flow path sector extends between two protrusions of the head 258b. Downstream of the spacers, the flow path is once again circular in cross section.

[0098] The valve 250 further comprises means 280, in this instance pneumatic means, of immobilizing the member 258 at least in its first position, which means to say its closed position.

[0099] The means 280 here comprise at least one elastically deformable membrane 282, which is mounted in an internal chamber 296 of the casing 252.

[0100] In the example depicted, the chamber 296 is delimited by the rear or downstream end of the wall 252bb, and in particular by a radial face 252bbl of this wall, and an annular cover 288 attached and fixed to this wall. The cover 288 in axial cross section is substantially U-shaped and comprises a cylindrical wall 288a of axis A of which one axial end situated on the same side as the inlet 254 is fixed to the wall 252bb and of which the opposite axial end is connected to a radial wall 288b. More specifically, the cover 288 comprises, at the free end of its wall 288a, a cylindrical centering and fixing flange 288aa intended to be engaged and fixed, for example by welding, on a cylindrical flange 252bbl of the wall.

[0101] The membrane 282 is annular or disk-shaped in its unstressed position. Its external periphery is fixed by clamping between the flanges 288aa, 252bbl . Its internal periphery is mounted clamped on the axial end of the opposite part 258a2 of the body to the head 258b. This part 258a2 of the body comprises a radial collar 259 on which the membrane 282 bears axially. This radial collar 259 extends radially outward as far as its external periphery which is bent over and oriented toward the inlet 254 of the valve. The membrane 282 espouses the shape of this collar, as is visible in FIGS. 9 and 10.

[0102] The membrane 282 divides the chamber 296 into two parts which are sealed from one another, these respectively being an upstream and a downstream part. The collar 259 is situated in the downstream part of the chamber 296. The wall 252bb of the casing 252 comprises at least one internal port 298 for drawing air into the downstream part of the chamber, in which part the radial collar 259 is situated (FIG. 11). This port 298 here opens onto the radial face 252bbl . [0103] When the immobilizing means 280 are not activated, the compression spring 270 urges the membrane 282 into a natural or unstressed position depicted in FIGS. 8 and 9, regardless of the position of the member 258 in the duct. In this position, the free end of the part 258a2 of the body presses axially against the radial wall 288b of the cover 288. The membrane 282 maintains this position as long as the immobilizing means 280 are not activated. When they are activated, the air contained in the downstream part of the chamber into which this port 298 opens is drawn in by the port 298 (arrow 300 in FIG. 11), which leads to a depression in this part, which has a tendency to reduce its volume. The reduction in its volume is obtained by the moving of the part 252a2 of the body until its collar 259 comes to bear axially against the radial face 252bbl of the wall 252bb, and by deformation of the membrane 282 (FIG. 10). The membrane 282 then adopts a stressed deformed shape. The head 258b is then kept pressed against its seat 266 by the return force exerted by the spring 270 in the stressed position, and/or by the free end of the part 258a2 of the body bearing axially against the free end facing the part 258al of the body, as can be seen in FIG. 10.

[0104] At least one of the parts 258al, 258a2 may be fitted with a seal intended to collaborate with the internal surface of the wall 252bb. A seal may for example be fitted in an external annular groove 302 of the part 258al, as in the example depicted (FIG. 9).

[0105] The chamber 296 may comprise return means, such as a compression spring 304, to urge the membrane 282 into its unstressed position. This spring may be aligned on the axis A, and bear axially on the upstream face of the collar 259 and on the downstream radial face 252bbl of the wall 252bb, respectively.