Expansion valve, particularly for refrigerant

Abstract

The invention relates to a pressure relief valve (1) for a fluid, said valve comprising a body (2), an insert (5) housed within said body (2), a housing (18), and a movable member (11), the insert (5) defining a cavity (6) for the passage of the fluid, said body (2) comprising a first conduit (3) and a second conduit (4) for the circulation of the fluid, said insert (5) creating a communication for the passage of the fluid between the first conduit (3) and the second conduit (4), through said cavity (6), in the open position of the valve, said insert (5) and said movable member (11) being configured so as to operate a pressure relief of the fluid between said cavity (6) and the second conduit (4) in at least one open position of the valve (1), and such that a first end (13) of the movable member (11) is flush with said second conduit (4) in a closed position of the valve (1), the housing (18) receiving a portion, referred to as the upper portion (14), of the moving part (11),opposite said first end (13), said valve (1) being configured to ensure a seal between the cavity (6) and the enclosure (18), the insert (5) comprising a channel (27) connecting the enclosure (18) and the second conduit (4). Figure in the abstract: Figure 1,

Description

Title of the invention: Expansion valve, in particular for refrigerant fluid Technical field

[0001] The present invention relates to an expansion valve. It could, for example, be used within a thermal management device of a motor vehicle, with a refrigerant fluid. Prior art

[0002] Within thermal management devices, cooling and / or heat pump type circuits rely on the compression and expansion of a refrigerant fluid in order to cool or heat another element such as, for example, an air flow to the passenger compartment and / or the batteries if it is an electric or hybrid vehicle. These circuits thus comprise at least one compressor to compress the heat transfer fluid and at least one expansion valve to expand it. Electronic expansion valves are known whose opening is controlled by a controlled motor. The degree of opening conditions the level of expansion. It is known that these expansion valves have a closure in which the heat transfer fluid cannot pass through the expansion valve and isolates a part of the circuit.

[0003] It is important that the overall architecture of electric vehicles is optimized so that their range and environmental performance are maximized. As part of this optimization strategy, specific work is being carried out to optimize the air conditioning systems of motor vehicles, including electric vehicles, for example in terms of weight and energy consumption. Components of these systems need to be improved without loss of functionality, such as expansion and isolation valves. Such improvements are also necessary in terms of the use of environmentally compatible refrigerants such as, for example, R744 (carbon dioxide, CO2).

[0004] The use of a fluid operating at high pressure and capable of exhibiting high pressure differentials such as R744 requires the application of forces at the expansion and isolation valves which are greater than with a more conventional fluid such as R1234yf. In addition, it is often necessary for the expansion valves to be able to reach a maximum opening level sufficient to cancel or minimize any pressure losses across said valves. The forces to be applied are all the greater as said maximum opening level to be reached is large. The valves compatible with meeting these needs are thus heavier, more bulky and more energy-consuming.

[0005] To overcome these drawbacks, needle valves for R744 are known for reducing the force applied by means of a passage passing internally through the needle and allowing fluid communication between a lower end and an upper part of the needle, leading to fluid pressure balancing between these two zones, which minimizes the effort required to move the needle.

[0006] A disadvantage of such positioning of said passage is that particles from the circuit can enter the passage and introduce themselves into the environment of the upper part of the needle and damage the mechanism for moving said needle, accessible in said environment.

[0007] An objective of the present invention is to overcome at least in part such a drawback. Summary

[0008] One aspect of the invention relates to a pressure relief valve for a fluid, said valve comprising a body, an insert, housed in said body, an enclosure and a movable member, the insert defining a cavity for the passage of the fluid, said body comprising a first and a second fluid circulation conduit, said insert creating a communication for the passage of the fluid between the first and second conduits, through said cavity, in the open position of the valve, said insert and said movable member being configured so as to operate a pressure relief of the fluid between said cavity and the second conduit in at least one open position of the valve and so that a first end of the movable member is flush in said second conduit, in a closed position of the valve, the enclosure receiving a part, called the upper part, of the movable member, opposite said first end, said valve being configured to ensure a seal between the cavity and the enclosure,the insert and / or the body comprising a channel connecting the enclosure and the second conduit, without communication with said cavity.

[0009] Thus, according to the invention, the channel allows communication of the fluid between the second conduit and the enclosure, leading to a pressure balance between the two opposite ends of the mobile member, this while limiting the risks of introduction of particles within the enclosure in the immediate vicinity of said mobile member.

[0010] Indeed, the positioning of the channel at the insert makes it possible to avoid such an introduction of particles into the enclosure, said positioning being arranged outside the flow of fluid circulating between the second conduit and the cavity, when the prior art has one end of the balancing passage at the bottom of a needle located in the flow of fluid and risking the introduction of particles.

[0011] It is understood that the term “flush” used above does not necessarily mean that the first end of the movable member projects into said second conduit but rather that this second end is subjected to pressure. established in said second conduit, in the closed position of the valve.

[0012] According to particular embodiments, the expansion valve may comprise one or more of the following characteristics, taken in isolation or in all technically possible combinations, which form(s) as many embodiment(s) of the invention: - the valve is configured so that the fluid flows from the first conduit to the second conduit, in at least one open position of the valve; - the valve is configured so that the fluid flows from the second conduit to the first conduit, in at least one open position of the valve; - the valve is configured so that the fluid circulates bidirectionally, the first conduit and second conduits alternately acting as fluid inlet or fluid outlet depending on the direction of circulation of said fluid, in at least one open position of said valve; - the valve is configured so that the fluid circulates without relaxation within said valve in at least one open position of said valve; - the second conduit has a baffle, one end of the channel opening into said baffle; - the canal is straight; - the insert has a recess; - the valve is configured so that the moving member moves in the insert along a translation axis; - the channel is parallel to the translation axis of the moving member; - the insert comprises a ring provided with a plurality of first orifices allowing communication for the passage of fluid between the first conduit and the second conduit, through the cavity; - said first orifices of the ring are radial; - the valve comprises a fluid distribution corridor in the insert, said corridor communicating with the first conduit; - the insert comprises a groove defining said corridor; - the expansion valve comprises a capsule defining a wall of the enclosure; - said capsule is in contact with the body; - said capsule is in contact with the insert; - the moving part consists of a needle; - the first end of the needle has a conical shape; - the insert comprises a seat for receiving the first end of the movable member; - the seat is formed around a second orifice of the insert opening into said second conduit; - A minimum diameter of the second orifice 16 of the insert 5 is less than a diameter of the second conduit 4; - the seat has an annular surface, in particular a truncated cone, defining a space for receiving the first end of the movable member; - the diameter of the seat receiving space corresponds to a diameter of the conical part of the needle allowing a closed position of the valve when the first end of the needle is in contact with said seat; - the enclosure comprises an actuator allowing the translation of the movable member between at least one open position and the closed position of the valve; - said actuator further allows the translation of the movable member between at least two distinct opening positions of the valve; - said actuator comprises a rotor, located in the enclosure; - said rotor is equipped with a worm screw; - the moving part is fitted with a screw thread allowing interaction with the screw endless rotor for the translation of said moving member. - the valve includes a seal ensuring the seal between the cavity and the enclosure; - the valve includes an internal seal between the insert and the body ensuring the seal between the first conduit and the second conduit in the closed position of the expansion valve; - the valve includes an external seal between the insert and the body ensuring the seal between the first conduit and the exterior of the expansion valve; - the valve is configured to operate with an operating fluid pressure of up to at least 135 bar, said fluid being, for example, R744; - the valve is configured to work with automotive refrigerants such as R1234yf or R 134a.

[0013] The invention also relates to an air conditioning system for a motor vehicle comprising the expansion valve as described above. Brief description of the drawings

[0014] Other characteristics, details and advantages of the invention will emerge more clearly on reading the description given below purely for illustrative purposes in relation to drawings in which: - [Fig.l] is a schematic view, along an axial section plane, of a valve according to the invention, in an open position; - [Fig.2] repeats [Fig.l], this time in a closed position of the valve; - [Fig.3] is a schematic view of an insert of said valve according to [Fig.l]; - [Fig.4] shows [Fig.l] in a first configuration of use according to the invention; - [Fig.5] reproduces [Fig.l] in a second configuration of use according to the invention. Description of the embodiments

[0015] It should first be noted that the figures set out the invention in detail for its implementation, said figures of course being able to serve to better define the invention, where appropriate.

[0016] In order to facilitate the reading of the figures, the different elements are not necessarily represented to scale. Certain elements or parameters may be indexed, that is to say designated for example by first element or second element, or even first parameter and second parameter, etc. This indexing is intended to differentiate similar, but not identical, elements or parameters. This indexing does not imply a priority of one element or parameter over another and the names may be interchanged.

[0017] In the following description, the term "a first element upstream of a second element" means that the first element is placed before the second element relative to the direction of circulation, or path, of a fluid. Similarly, the term "a first element downstream of a second element" means that the first element is placed after the second element relative to the direction of circulation, or path, of the fluid in question.

[0018] [Fig.l] illustrates an expansion valve 1 for a fluid which is the subject of the present invention according to one embodiment. Said valve 1 comprises a body 2.

[0019] Said body 2 is for example formed from a block of aluminum in the shape of a straight block machined to obtain the desired arrangements within said body 2.

[0020] The body 2 comprises a first conduit 3 and a second conduit 4 for circulating the fluid.

[0021] The first conduit 3 has a first end and a second end, said first end of said first conduit 3 opening towards the outside of the body 2.

[0022] The second conduit 4 has a first end and a second end, said second end of said second conduit 4 opening out towards the outside of the body 2.

[0023] As illustrated in [Fig.l] the first end of the first conduit 3 is positioned on a first face of the straight block defining the body 2 and the second end of the second conduit 4 is positioned on a second face of said straight block defining said body 2, said second face being perpendicular to the first face. first end of the conduit 3 is substantially centered in the first face of the straight block defining the body 2. The second end of the conduit 4 is substantially centered in the second face of the straight block defining the body 2

[0024] As illustrated in [Fig.4] in a first configuration of use of the valve 1, in an open position of said valve 1, the fluid, the circulation of which is represented by arrows A and A', enters the valve through the first conduit 3 and exits through the second conduit 4.

[0025] As illustrated in [Fig.5] in a second configuration of use of the valve 1, in an open position of said valve 1, the fluid, the circulation of which is represented by arrows B and B', enters the valve 1 through the second conduit 4 and exits through the first conduit 3.

[0026] In the embodiment of the valve 1 illustrated in [Fig.l], the first conduit 3 and the second conduit 4 have perpendicular directions. The first conduit 3 and the second conduit 4 have a circular cross-section, over at least part of their length, said part including respectively the first end of the first conduit 3 and the second end of the second conduit 4.

[0027] The valve further comprises an insert 5, housed in the body 2.

[0028] Said insert 5 is for example formed from a cylindrically shaped aluminum block machined to obtain the desired arrangements within said insert 5.

[0029] The insert 5 defines a cavity 6 for the passage of the fluid.

[0030] Said insert 5 creates a communication for the passage of the fluid between the first conduit 3 and the second conduit 4, through said cavity 6.

[0031] [Fig. 3] is a schematic view of the insert 5 according to an exemplary embodiment. Naturally, said valve 1 according to the invention may comprise an insert having another configuration. Similarly, the insert 5 according to said exemplary embodiment of [Fig. 3] may be used in a valve 1 having other configurations, while remaining within the scope of the invention.

[0032] In said exemplary embodiment, the insert 5 comprises, or even consists of, a ring 7 provided with a plurality of first orifices 8 allowing the passage of fluid between the first conduit 3 and the cavity 6.

[0033] In said embodiment of the insert 5, the first orifices 8 of the ring 7 are radial. There are at least two of said first orifices 8. In said embodiment, there are eight of them. They are regularly spaced apart, angularly around a longitudinal axis 15 of the insert 5. They are cylindrical in shape and of the same diameter. They are substantially located at the same level along said longitudinal axis 15. The radial plane in which said first orifices 8 extend is substantially at the same distance from the upper and lower bases of the ring 7 constituting the insert 5.

[0034] In said embodiment, the insert 5, the cavity 6 is formed from a first cylinder whose axis of revolution corresponds to the longitudinal axis 15, into which the first orifices 8 open.

[0035] The valve 1 comprises a passage 9 for distributing the fluid in the insert 5, said passage 9 communicating with the second end of the first conduit 3, on the one hand, and / or said first orifices 8, on the other hand.

[0036] In said exemplary embodiment of the insert 5, the insert 5 comprises a groove 10 defining said corridor 9. Said groove has a first side, open, and a second side opposite the first side and forming a bottom of said groove 10. The first side of said groove 10 communicates with the second end of the first conduit 3 and the second side of said groove 10 communicates with the first orifices 8. The first side has a height substantially equal to a height of the second end of the first conduit 3. The second side of said groove 10 has a height at least equal to the diameter of said first orifices 8.

[0037] According to an exemplary embodiment not shown, the body 2 comprises the corridor 9 which then surrounds the insert 5.

[0038] In the illustrated embodiment of the valve 1, the insert 5 comprises a first base and a second base, connected by a lateral face having said orifices 8. The first base, called the lower base, of the insert 5 is parallel to the second face of the straight block defining the body 2, and the second base, called the upper base, of the insert 5 is parallel to a third face of the straight block defining the body 2, said third face being opposite the second face.

[0039] In the illustrated embodiment of the valve 1, the insert 5 has a privileged position. In particular, an external face of the upper base is located in the same plane as an external face of the body 2. Even more precisely, here, the lower base of the ring 7 is in a plane located below the first conduit 3 and above a first end of the second conduit 4 opposite the second end of said second conduit 4, and / or the upper base of said ring 7 is in a plane substantially coincident with the third face of the straight block defining the body 2 and in which the longitudinal axis 15 is centered in the body 2.

[0040] As illustrated in [Fig.2], the valve 1 comprises a movable member 11.

[0041] In the illustrated embodiment, the movable member 11 consists of a needle 12.

[0042] A first end 13 of said needle 12 is a so-called lower end of said needle 12.

[0043] A second, opposite end 14 of said needle 12 is a so-called upper end of said needle 12.

[0044] In this embodiment, the first end 13 has a conical shape, or even truncated.

[0045] The valve 1 is configured so that the movable member 11 moves in the insert 5 along a translation axis, corresponding here to said longitudinal axis 15 of the insert.

[0046] As illustrated in [Fig.l], the insert 5 has a recess 16, for example formed in the upper base.

[0047] In said embodiment of the insert 5, the recess 16 is formed by a second cylinder whose axis of revolution corresponds to the longitudinal axis 15. Said second cylinder is positioned in the upper extension of the first cylinder forming the cavity 6. Said second cylinder has a diameter smaller than the diameter of the first cylinder.

[0048] The insert 5 is configured so that the movement of the movable member 11 takes place in the recess 16 and / or the cavity 6.

[0049] In this embodiment, the translation axis 15 is parallel to the direction of the second conduit 4, said translation axis 15 extending into said second conduit.

[0050] As illustrated in [Fig.2], the insert 5 comprises a seat 17 for receiving the first end 13 of the movable member 11, said seat 17 being for example arranged in the lower base.

[0051] The first end 13 of the movable member 11 is in contact with the seat 17 in a closed position of the valve 1, as illustrated in [Fig.2].

[0052] The seat 17 is formed around a second orifice 16 of the insert 5 opening into said second conduit 4.

[0053] A minimum diameter of the second orifice 16 of the insert 5 is, for example, less than the diameter of the part of the second conduit 4 having a right circular section.

[0054] In this embodiment, the seat 17 has an annular surface, in particular a frustoconical one, defining a space for receiving the first end 13 of the movable member 11.

[0055] In this embodiment, the truncated cone of the first end of the movable member 11 and the truncated cone defining the seat 17 are complementary: a diameter of the truncated cone of the seat 17 corresponds to a diameter of the conical part of the needle 12.

[0056] The closed position of the valve 1 illustrated in [Fig.2] makes it possible to isolate the fluid occupying the cavity 6 from the fluid occupying the second conduit 4, the first end 13 of the needle 12 in contact with said seat 17 preventing any flow of fluid between the cavity 6 and the second conduit 4, and guaranteeing the seal between these two zones.

[0057] As illustrated in [Fig.2], the valve 1 comprises an enclosure 18.

[0058] In this embodiment, the enclosure 18 is positioned on the outer side of the third face of the right block defining the body 2. The enclosure 18 is substantially centered relative to said third face.

[0059] The expansion valve 1 comprises a capsule 19 defining a wall of the enclosure 18.

[0060] In the embodiment of the valve 1 illustrated in [Fig.l], the upper base of the ring 7 constituting the insert 5 is at least partly in contact with the enclosure 18.

[0061] In the embodiment of the valve 1 illustrated in [Fig.l], the capsule 19 is in contact with the insert 5 to close said enclosure 18 in a sealed manner with respect to the outside.

[0062] According to an embodiment of the valve 1 not shown, the capsule 19 is in contact with the body 2.

[0063] The enclosure 18 comprises at least in part an actuator 20 allowing the translation of the movable member 11 between at least one open position and one closed position.

[0064] The actuator 20 makes it possible to obtain several opening positions by translation of the movable member 11.

[0065] In the embodiment of the valve 1 illustrated in [Fig.l], the actuator 20 comprises a rotor 21 provided with a worm screw 22.

[0066] The movable member 11 is provided with a screw thread allowing interaction with the worm screw 22 of the rotor 21 for the translation of said movable member 11. The movable member 11 has a key, not visible in the figures, embedded in a groove of the insert 5, preventing any rotational movement of said movable member 11 around the translation axis 15. According to an embodiment not shown, the valve 1 comprises a fixed nut. The screw of the rotor 21 rotates in said fixed nut, the rotor 21 and its screw 22 thus moving in translation along the translation axis 15 with each rotational movement. A lower end of said screw 22 is in contact with an upper part of a spring whose winding axis is substantially coincident with the translation axis 15 of said screw 22. A lower part of said spring is in contact with the movable member 11. The position of the movable member 11 along the translation axis 15 then depends on the axial position of the screw 22 and the forces exerted on either side on said spring.

[0067] The second end 14 of the movable member 11 is housed in the enclosure 18 inside which it moves between a high position corresponding to the position of greatest opening of the valve and a low position corresponding to the closed position of the valve.

[0068] In the embodiment of the valve 1 illustrated in [Fig.l], the so-called upper part of the movable member 5 is provided with a bore 23 provided with the screw thread allowing interaction with the worm screw 22 of the rotor 21 for the translation of said member mobile 11 along the translation axis 15.

[0069] As illustrated in [Fig.l], said valve 1 comprises a first seal 24 ensuring sealing between the cavity 6 and the enclosure 18.

[0070] As illustrated in [Fig.2], said valve 1 comprises a second internal seal 25 between the insert 5 and the body 2 ensuring sealing between the first conduit 3 and the second conduit 4 in the closed position of the expansion valve 1.

[0071] As illustrated in [Fig.l], said valve 1 comprises a third external seal 26 between the insert 5 and the body 2 ensuring the seal between the first conduit 3 and the exterior of the valve 1.

[0072] [Fig.4] illustrates the valve 1 according to a first configuration of use of the valve 1. In said first configuration of use, said valve 1 is configured so that the fluid circulates from the first conduit 3 to the second conduit 4, in the open positions of the valve 1.

[0073] [Fig.5] illustrates valve 1 according to a second configuration of use of the valve 1. In said second configuration of use, said valve 1 is configured so that the fluid circulates from the second conduit 4 to the first conduit 3, in the open positions of the valve 1.

[0074] The insert 5 and the movable member 11 are configured so as to operate an expansion of the fluid between said cavity 6 and the second conduit 4.

[0075] More precisely, here, a fluid passage section between the first end 13 of the needle 12 and the seat 17 allows the expansion of the refrigerant fluid.

[0076] A translation of the needle 12 from a first opening position of the valve 1 to a second opening position of the valve 1 allows a modification of said passage section and causes a modification of the expansion level of the refrigerant fluid circulating in the valve 1.

[0077] An open position of the valve called maximum opening allows circulation of the fluid without expansion between the first conduit 3 and the second conduit 4.

[0078] In the first configuration of use illustrated in [Fig. 4], the fluid enters the valve 1 through the first conduit 3 and is then distributed into the cavity 6 through the first radial orifices 8 from the passage 9. This arrangement allows a homogeneous distribution of the fluid around the movable member 11 in the cavity 6. Said fluid then passes through the passage section between the needle 12 and the seat 17 before joining the second conduit 4 through the first end of said second conduit 4 and leaves the valve 1 through the second end of said second conduit 4.

[0079] In the second configuration of use illustrated in [Fig. 5], the fluid enters the valve 1 through the second end of the second conduit 4, leaves the second conduit 4 through the first end of said conduit 4, crosses the passage section between the first end 13 of the needle 12 and the seat 17, then is distributed around the movable member 11 in the cavity 6. Said fluid then passes through the first radial orifices 8 before joining the corridor 9 from which said fluid enters the first conduit 3 through the second end of said first conduit 3, then leaves the valve 1 through the first end of said first conduit 3.

[0080] The valve 1 is configured so that the fluid circulates bidirectionally, in open positions of said valve, the first conduit and second conduit acting alternately as fluid inlet or fluid outlet depending on the direction of circulation of said fluid as illustrated in Figures 4 and 5.

[0081] As illustrated in [Fig.3], according to the invention, the insert 5 and / or the body 2, here the insert 5 only, comprises a channel 27 connecting the enclosure 18 and the second conduit 4.

[0082] The channel 27 allows the fluid in the second conduit 4 to be at the same pressure as the fluid in the enclosure 18. The pressure exerted by the fluid on the upper part of the movable member 11 is then similar to the pressure exerted by the fluid on the first end 13 of said movable member 11, at least in the closed position of the valve, or even in the event of a transition between the closed position and the open position or one of the open positions, or in the event of a transition between two of the open positions. The force to be applied by the actuator 20 for the translation of the movable member 11 is thus reduced thanks to the presence of said channel 26. The valve 1 is particularly suitable for use with refrigerant fluids having operating pressures of up to at least 135 bar, such as R744.Preferably, valve 1 is also compatible with more conventional automotive refrigerants such as R1234yf or R 134a.

[0083] Furthermore, positioning the channel 27 in the insert allows the portion of fluid located near the end of the channel 27 opening into the second conduit 4 to be moved away from the portion of the fluid forming the flow passing through the second orifice and subjected to strong turbulence, in the open position of the valve.

[0084] In the embodiment of the insert 5 illustrated, the channel 27 is rectilinear.

[0085] In the embodiment of the insert 5 illustrated, the channel 27 is parallel to the axis of translation 15.

[0086] The channel 27 passes through the insert 5 between two of the first orifices 8, which are adjacent, at a distance from the longitudinal axis 15 between an internal radius of the insert 5 and a minimum radius of the corridor 9. It is here located, angularly, close to the second end of said first conduit, or even in the axis of said first conduit.

[0087] Advantageously, the second conduit 4 has a baffle 28 communicating with the end of the channel 27 opening into said second conduit 4.

[0088] The baffle 28 allows the portion of fluid located near the end of the channel 27 opening into the second conduit 4 to be protected from the turbulence generated at the second orifice. The arrangement of the baffle 28 allows reduce the risk of introduction into the channel 27 of particles coming from another part of the circuit in which the valve 1 is used. The introduction of said particles into the channel 27 would allow their introduction into the enclosure 18 in which at least part of the actuator 20 is housed, and could compromise the proper functioning of said actuator 20.

[0089] Said baffle 28 is formed by a flaring of the first end of the second conduit 4, delimited above by the insert 5 and delimited below and / or laterally by the body 2. In the embodiment of the valve 1, said flaring is delimited below by an internal face of the body 2 perpendicular to the translation axis 15, and delimited laterally by an internal face of the body 2 parallel to the translation axis 15. The flaring has a constant diameter.

Claims

Claims

1. A fluid-relieving valve (1), said valve comprising a body (2), an insert (5) housed in said body (2), an enclosure (18) and a movable member (11), the insert (5) defining a cavity (6) for the passage of the fluid, said body (2) comprising a first conduit (3) and a second conduit (4) for circulating the fluid, said insert (5) creating a communication for the passage of the fluid between the first conduit (3) and the second conduit (4), through said cavity (6), in the open position of the valve, said insert (5) and said movable member (11) being configured so as to operate a fluid-relieving valve between said cavity (6) and the second conduit (4) in at least one open position of the valve (1) and so that a first end (13) of the movable member (11) is flush with said second conduit (4) in a closed position of the valve (1), the enclosure (18) receiving a part, called the upper part (14), of the moving member (11),opposite said first end (13), said valve (1) being configured to ensure a seal between the cavity (6) and the enclosure (18), the insert (5) and / or the body (2) comprising a channel (27) connecting the enclosure (18) and the second conduit (4).,

2. Relief valve (1) for a fluid according to the preceding claim, in which the second conduit (4) has a baffle (28), one end of the channel (27) opening into said baffle (28).

3. A fluid relief valve (1) according to any preceding claim, wherein the channel (27) is rectilinear.

4. A fluid relief valve (1) according to any preceding claim, wherein the channel (27) is parallel to a translation axis (15) along which the movable member (11) moves in the insert (5).

5. A fluid relief valve (1) according to any preceding claim, wherein the insert (5) comprises a ring (5) provided with a plurality of first orifices (8) allowing communication for the passage of fluid between the first conduit (3) and the second conduit (4), through the cavity (6).

6. A fluid-relief valve (1) according to any one of the preceding claims, wherein the insert (5) comprises a seat (17) for receiving the first end (13) of the movable member (11), said seat (17) being formed around a second orifice (16) of the insert (5) opening into the second conduit (4). A diameter of the second orifice (16) is less than a diameter of the second conduit (4).

7. A fluid relief valve (1) according to any one of the preceding claims, comprising a capsule (19) defining a wall of the enclosure (18), said capsule (19) being in contact with the insert (5).

8. A fluid pressure relief valve according to any preceding claim, wherein the movable member (11) consists of a needle (12).

9. A fluid relief valve (1) according to any one of the preceding claims, comprising a seal (24) ensuring sealing between the cavity (6) and the enclosure (18).

10. Air conditioning system for a motor vehicle comprising the expansion valve (1) according to any one of the preceding claims.