IT202100001271A1 - THERMAL PROTECTION DEVICE FOR A HYDRAULIC SYSTEM - Google Patents

Description

Description of industrial invention

Entitled: ?Thermal protection device for a hydraulic system?

Background of the invention

[0001] The invention relates to a thermal protection device arranged to protect a hydraulic system in which a heat transfer fluid circulates, in particular water, from extreme temperatures which jeopardize the operation of the hydraulic system itself and of its component parts, such as valves , pipes, heat exchangers, etc..

[0002] Specifically, but not exclusively, the protection device according to the invention can be applied to a thermal system, such as a heating apparatus, and/or to an energy conversion system, such as a solar or photovoltaic type system. In these applications, the hydraulic system (or parts of it) may be subject to significant temperature variations due to operation? of the system itself or to the climatic conditions of the external environment.

[0003] The invention can be applied both in the domestic and in the industrial field in all cases where ? provided that the heat transfer fluid of a hydraulic system is exposed to possible significant variations in temperature.

[0004] In fact, the heat transfer fluid, particularly in the case of water or a water-based liquid, at low temperatures (close to 0°C) undergoes an expansion when it freezes, i.e. it increases its specific volume, with the risk of cause damage and/or breakage of the hydraulic system components.

[0005] ? a thermal protection device is known for a hydraulic system in a building, comprising an anti-freeze valve. This antifreeze valve is installed in an area located outside the building so as to be sensitive to the outside temperature.

[0006] The operation of this antifreeze valve is based on an obturator group comprising a thermosensitive element, or antifreeze thermostat, for example in wax, capable of undergoing dimensional variations according to its temperature and an obturator element, which can be operated by the thermosensitive element to selectively open or close an opening which allows the drainage of the heat transfer fluid towards the external environment. In particular, the thermosensitive element respectively undergoes an expansion with an increase in temperature and a contraction with a decrease in temperature. The thermosensitive element? configured to pilot the shutter group in opening, in particular, when the temperature ? lower than a minimum threshold temperature in order to evacuate the water remaining in the hydraulic system, for example in a pipe, draining it towards the outside or towards a tank. There? allows to avoid freezing, and therefore, the expansion of the heat transfer fluid - due to the low temperatures - inside the hydraulic system and the consequent damage of the latter.

[0007] A limitation of the aforementioned hydraulic systems? given by the difficulty? to preserve them from possible damage caused by high temperatures. Pi? precisely, the antifreeze valve described above, although able to operate effectively at low temperatures, is itself subject to possible damage in the event of excessively high temperatures. In particular, the heat-sensitive element placed inside the antifreeze valve is easily perishable at high temperatures, especially during colder seasons. hot.

[0008] The deterioration of the thermosensitive element therefore compromises the operation, the duration and the reliability? of? unit? antifreeze valve thus exposing the hydraulic system to possible risks of breakage due to the expansion of ice inside the pipes.

[0009] In the light of the foregoing, it would therefore be desirable to have a thermal protection device capable of overcoming all the limits set forth above and which is also capable of operating effectively at different temperature levels, in particular at high temperatures.

Purposes of the invention

[0010] A purpose of the invention? to obviate the limitations and drawbacks of the prior art set forth above.

[0011] Another purpose? to provide a solution that allows you to preserve the optimal operation of a unit? antifreeze valve, effectively protecting it from the risk of damage caused by high temperatures.

Brief description of the invention

[0012] These aims, and others still, are achieved thanks to a thermal protection device for a hydraulic system in which a heat transfer fluid circulates, in particular water, as defined in the attached claims.

[0013] In one version, the thermal protection device suitable for a hydraulic system comprises a unit? antifreeze valve which includes: an antifreeze valve body provided with an inlet connection and a? end? outlet for a heat transfer fluid circulating in the hydraulic system; a thermosensitive shutter group configured to evacuate the heat transfer fluid from the extremity? output when a minimum threshold temperature is reached cos? to avoid damage to the hydraulic system due to freezing of the heat transfer fluid; the thermal protection device further comprises a cooling device arranged to cool the heat transfer fluid and keep it below a maximum threshold temperature so? to preserve the thermosensitive shutter group from damage, the cooling device being defined by a tubular duct, extending along a longitudinal axis and able to be crossed internally by the heat transfer fluid and equipped with one end? coupling configured to couple with the input attack of the unit? antifreeze valve, on the tubular duct being obtained one or more? elements protruding outwards for the heat exchange of the heat transfer fluid with the external environment.

[0014] Thanks to the device according to the invention, ? Is it possible to safely operate a hydraulic system equipped with a?unit? antifreeze valve in particular in conditions of different operating temperatures of the heat transfer fluid without jeopardizing the correct operation of the unit? valve antifreeze and l?integrit? structural of the hydraulic system.

[0015] The device according to the invention allows to preserve the thermosensitive shutter group of the unit? antifreeze valve in particular from damage due to high temperatures.

[0016] Thanks to the solution according to the invention, ? is it possible to increase the duration and reliability? of a hydraulic system.

[0017] Thanks to the solution according to the invention, an economical and simple thermal protection device is provided from a constructive and functional point of view.

Brief description of the drawings

[0018] The invention can be better understood and implemented with reference to the attached drawings which illustrate a non-limiting example of implementation, in which:

figure 1 ? an exploded view of an embodiment of a thermal protection device in which components of the device are shown, in an open position. figure 2 ? a longitudinal section, taken along a median plane, of the thermal protection device of figure 1;

figure 3 ? a side view of the thermal protection device of figure 1.

Detailed description

[0019] The general characteristics of the present invention will be illustrated hereinafter through an embodiment.

[0020] Referring to the aforementioned figures 1, 2, and 3, with 10 ? A thermal protection device according to the present invention has been indicated. This thermal protection device 10 ? particularly suitable for being installed in a plumbing system (not shown), in particular in an industrial or domestic plumbing system arranged to operate with a heat transfer fluid, such as water.

[0021] The thermal protection device 10 according to the invention allows the correct functioning of the hydraulic system, protecting it from the risk of damage, even when the heat transfer fluid is ? subjected to high temperatures.

[0022] For example, a heat transfer fluid for domestic use (heating, domestic hot water) can reach temperatures over 50 ?C, while a heat transfer fluid used for industrial uses (energy production, industrial processes) can? assume temperatures even of the order of hundreds of degrees.

[0023] The thermal protection device 10, which can be installed outside a room or building, can be used advantageously in all those hydraulic systems which are exposed to rather severe climatic regimes and/or to sensitive temperature ranges. In particular, the thermal protection device 10, in addition to protecting the system from low temperatures (at which there is a risk of freezing of the heat transfer fluid), also successfully performs an effective function of protection against excessively high temperatures, typical of the summer season .

[0024] An example of this type of hydraulic system? that serving solar panels, in particular those of a solar thermal system. In fact, since Are the solar panels installed in the external environment (for example on a roof or on the ground) in order to effectively receive solar radiation, at least a part of this plumbing system? necessarily exposed to extreme temperatures.

[0025] With reference to figures 1, 2 and 3, the thermal protection device 10 comprises, in particular, a unit? antifreeze valve 20 arranged to protect the hydraulic system from damage due to freezing of the water present in the pipes of the hydraulic system. The unit The antifreeze valve 20 includes, in particular, an antifreeze valve body 21a, 21b provided with an inlet connection 22 arranged to receive at the inlet the heat transfer fluid circulating in the hydraulic system and an end outlet 23 arranged to evacuate the heat transfer fluid from the antifreeze valve body 21a, 21b.

[0026] The antifreeze valve body 21a, 21b defines within it a chamber, or cavity? of housing 21c of elongated shape, having in particular a shape of a cylinder which is arranged to house, in particular in a movable way, a shutter group 24 which will be described below. The cavity? housing 21c extends along a respective longitudinal axis M. The inlet connection 22 and the outlet connection 23 are in fluid communication with the cavity? of housing 21c. The antifreeze valve body 21a, 21b comprises, in particular, a first half shell 21a and a second half shell 21b connected to each other. In the specific example shown in the figures, the first half shell 21a and the second half shell 21b are configured to be connected via a threaded coupling; however, in another version not illustrated, you can? provide for a different connection or, alternatively, you can? make the antifreeze valve body in a single piece and have, for example, a cap, or closure, at one end? of the valve body, cos? to allow the insertion of the shutter group 24 inside the cavity? of housing 21c.

[0027] The cavity? housing 21c comprises, in particular, an inlet opening 22b for the heat transfer fluid. This entrance opening 22b can comprising, in particular, a through hole, in particular circular in shape, defined by an annular sealing element 29 configured to be crossed by the heat transfer fluid. The entrance opening 22b ? configured to put the inlet connection 22 in fluid communication with the inside of the cavity? housing 21c for the passage of the heat transfer fluid. This sealing element 29 ? inserted in an annular entrance seat 22c obtained in the cavity? housing 21c between the inlet connection 22 and the inside of the cavity? of housing 21c. The sealing element 29 ? equipped with an abutment surface 29a arranged to act as an abutment to a shutter element, to selectively open and close the inlet opening 22b as it will be? described below.

[0028] The cavity? housing 21c comprises, in particular, a support seat 23a arranged at the end? outlet 23 and shaped to receive the shutter group 24 in support. The support seat 23a ? provided with at least one outlet opening (not shown) arranged to allow the evacuation of the heat transfer fluid from inside the antifreeze valve body 21a, 21b towards the outside through the end? exit 23.

[0029] The unit? antifreeze valve 20 comprises, in particular, a thermosensitive obturator unit 24 configured to evacuate the heat transfer fluid from the end of the valve; output 23 upon reaching a minimum threshold temperature cos? to avoid damage to the hydraulic system due to freezing of the carrier fluid.

[0030] The minimum threshold temperature can? be set, in particular, to be close to, or slightly above, the freezing point of water.

[0031] For example, the minimum threshold temperature can? be equal to about 4-5 ?C.

[0032] The obturator group 24 comprises, in particular, a thermostatic actuator, or thermosensitive element 25, configured to contract according to a drop in temperature so as to allow the passage of the heat transfer fluid inside the valve body 20 and therefore to evacuate the heat transfer fluid through the? end? exit 23.

[0033] The thermosensitive element 25 can comprise, in particular, a cylinder body provided at one of its bases with a portion or a control rod 25a, which protrudes from the cylinder body along the longitudinal axis M. This control rod 25a ? configured to be movable axially - with respect to the longitudinal axis M - according to the temperature of the thermosensitive element 25 between a retracted position and an extended position, how will it be? explained below.

[0034] The thermosensitive element 25 can comprise, in particular, an annular portion provided with a support surface 25b facing the end? outlet 23 to contact the support seat 23a of the antifreeze valve body 21a, 21b so as to prevent an axial displacement (along the longitudinal axis M) of the thermosensitive element 25.

[0035] The thermosensitive element 25 comprises a thermosensitive material, susceptible to volume variations as a function of the temperature. The thermosensitive material can? include a solid material, such as wax, a liquid or a gas.

[0036] With reference to figure 2, when is the temperature of the thermosensitive element 25 ? low, in particular when ? below the minimum temperature threshold, the thermosensitive substance? contracted and the?rod of command 25a? in the retracted position. In this condition, the passage is freed and the evacuation of the fluid is enabled.

[0037] When is the temperature of the thermosensitive element 25 ? high, in particular when ? above the minimum temperature threshold, the thermosensitive substance? expanded and the command rod 25a ? in the extended position (not shown) which closes the passage to the fluid. The time interval between the thermal change and the corresponding volumetric change of the substance, i.e. the response time of the substance, can? vary according to the type of thermosensitive substance used for the thermosensitive element 25.

[0038] The obturator group 24 comprises, in particular, a cup-shaped obturator element 26 which can slide axially with respect to the longitudinal axis M inside the cavity. of housing 21c. The shutter element 26 ? operatively connected to the thermosensitive element 25 so that the control rod 25a moves the shutter element 26 towards and away from the inlet opening 29b, respectively to block and open the inlet opening 22b.

[0039] The shutter element 26 comprises, in particular, an end hollow 26a in particular of cylindrical shape arranged to house a portion of the control rod 25a, so that the obturator element 26 can undergo an axial thrust from the control rod 25a when the control rod 25a passes from the retracted position to the extended position. The end? quarry 26a ? equipped with one or more protrusions 26c which extend in a radial direction with respect to the longitudinal axis M for contacting a lateral surface of the cavity? of housing 21c. Are the protrusions 26c configured to slide on the lateral surface of the cavity? housing 21c and are spaced angularly so as to leave free one more? passages configured to allow the fluid to flow along a path which goes from the inlet opening 22b to the end? exit 23.

[0040] The shutter element 26 comprises, in particular, an end of? engagement 26b cylindrical opposite all? extremity? hollow 26a, arranged to contact the abutment surface 29a of the sealing element 29 so as to close the inlet opening 22b when the control rod 25a is in contact. in the extended position. In the specific example shown in the figures, a side wall of the end? of? commitment 26b ? configured to contact the at least one abutment surface 29a in a sealed manner when the control rod 25a ? in the extended position cos? to prevent the passage of the carrier fluid between the inlet connection 22 and the outlet connection 23 through the inlet opening 22b.

[0041] In the specific example shown in figure 2, the axial thrust of the control rod 25a is opposed by an elastic element 27, such as a pre-compressed spring.

The elastic element 27 ? arranged in particular to urge the shutter element 26 towards the end? d? exit 23, in order to remove the? extremity? of engagement 26b from the abutment surface 29a thus allowing? the passage of the heat transfer fluid through the inlet opening 22b. In fact, the thermosensitive element 25 undergoes a contraction - corresponding to a temperature lower than the minimum threshold temperature - along the cavity? of housing 21c, causing a disengagement and a moving away of the shutter element 26 from the inlet opening 22b to cause the evacuation of the heat transfer fluid through the end? exit 23.

[0042] The shutter group 24 can? comprise, in particular, an annular body 28 of hollow cylindrical shape, provided with an end? contact 28b arranged to contact and press a surface of the annular element 29 facing the end? outlet 23 so that the annular element 29 is retained in the inlet seat 22c. The annular body 28 comprises, in particular, a threaded outer lateral surface arranged for screwing the annular body to a corresponding threaded portion of the cavity. of housing 21c. The annular body 28 comprises, in particular, one end support 28c opposite to? of contact 28b of annular shape disposed to support a? end? of the elastic element 27.

[0043] The annular body 28 comprises, in particular, a hole 28d arranged to be crossed by the heat transfer fluid provided with longitudinal ribs, i.e. arranged according to the longitudinal axis M, able to guide the end of engagement 26b of the shutter element 26 in particular when the shutter element approaches the inlet opening 22b to engage the sealing element 28.

[0044] The protection device 10 comprises, in particular, a cooling device 30 arranged to cool the heat transfer fluid and keep it below a maximum threshold temperature so to protect the thermosensitive shutter unit 24 from damage.

[0045] The cooling device 30 ? defined, in particular, by a tubular duct 31, which extends along its own longitudinal axis L, capable of being traversed internally by the carrier fluid. Referring in particular to Figure 2, the tubular duct 31 has a hollow cylindrical shape. In particular, the tubular duct 31 extends for a length A comprised between 50 mm and 100 mm.

[0046] The cooling device 30 ? endowed, in particular, of a? Extremity? coupling 32 configured to couple with the input connection 22 so as to fluidly connect the cooling device 30 and the unit? antifreeze valve 20.

[0047] In the specific example shown in the figures, the end coupling 32 comprises a thread for coupling with a female screw obtained on the input attachment 22 of the unit? antifreeze ring 20. The end? d?coupling 32 pu? further comprise an annular seat for housing a sealing gasket 22a.

[0048] The tubular duct 31 and the end? coupling valves 32 are configured in such a way that the tubular duct 31, coupled to the antifreeze valve body 21a, 21b, is positioned with its own longitudinal axis L oriented transversally with respect to the longitudinal axis M of the unit? antifreeze valve 20. In other words, ? It is possible to provide that the cooling device 30 is shaped in such a way that the longitudinal axis L of the tubular duct 31 forms any desired angle with the longitudinal axis M of the unit? antifreeze valve 20. In particular, the desired angle between the longitudinal axes L and M pu? be in the range of 90? and 180?.

[0049] In the specific example shown in figures 2 and 3, the longitudinal axis L of the tubular duct 31 and the longitudinal axis M of the unit antifreeze valve 20 are mutually perpendicular.

[0050] In a further version not shown, the tubular duct 31 and the end coupling 32 can be configured in such a way that the tubular duct 31 is positioned with its own longitudinal axis L aligned, or parallel, to the longitudinal axis M of the unit? antifreeze valve 20.

[0051] On the tubular duct 31, in particular, one or more transversely oriented protruding elements 33, in particular perpendicular to the longitudinal axis L.

[0052] Each protruding element 33 comprises, in particular, a plate-like body, i.e. having two dimensions (for example length and width) prevailing with respect to a thickness, so as to increase the heat exchange surface of the tubular duct 31.

[0053] Such one or more? protruding elements 33 comprise respective mutually spaced annular portions distributed on the tubular duct 31 along the longitudinal axis L.

[0054] To obtain an efficient heat exchange between the heat transfer fluid and the external environment and at the same time a reduced size of the thermal protection device 10, the number n of the protruding elements 33 ? chosen to be included in the range between 1 and 4 per unit? length expressed in centimeters. With reference to the specific example of the figures, the cooling device 30 comprises 15 elements over a length of about 60 mm, which corresponds to a number of protruding elements 33 of about 3 per centimetre.

[0055] The one or more? protruding elements 33 comprise, in particular, respective heat exchange surfaces 33a, 33b adapted to be lapped by the air of the external environment to allow heat exchange between the vector fluid and the external environment itself.

[0056] In the specific example shown in figures 1, 2 and 3, the protruding elements 33 comprise annular or discoidal portions, mutually separated and distributed along the tubular duct 31. Each annular portion comprises an extremity connected to the tubular duct 31 and one end? free peripheral. Each annular portion defines, in particular, two heat exchange surfaces 33a, 33b, opposite each other, in particular in the shape of a circular crown. Each heat exchange surface 33a, 33b has an area between 100 mm<2> and 200 mm<2>.

[0057] In a non-illustrated version, the one or more? protruding elements 33 define a single helical portion which develops around the tubular duct 31 along the longitudinal axis L.

[0058] In a further version not illustrated, the one or more? protruding elements 33 can comprise, in particular, respective heat exchange fins. The heat exchange fins can have the shape of a rectangular plate, in particular rectangular or square.

[0059] The cooling device 30 ? equipped, in particular, with a further extremity? coupling 34 configured to mate with a connection fitting 40 arranged to fluidly connect the cooling device 30 (and the thermal protection device 10) to a branch of the hydraulic system. In the illustrated version, the connection fitting 40 internally comprises a nut thread for coupling to a corresponding thread formed at one end of the plumbing branch.

[0060] In the specific example shown in the figures, the further end? of coupling 34 comprises a flange portion configured to allow a rotation of the connection fitting 40 about the longitudinal axis L during the coupling by screwing of the fitting 40 with the branch of the hydraulic system.

[0061] The further end? coupling 34 ? arranged to receive a filter 41, in particular a dome filter, to protect the thermal protection device 10 from mechanical damage or unwanted clogging caused by debris, dirt and particles carried by the incoming heat transfer fluid.

[0062] The connection fitting 41 comprises, in particular, an annular locking element 42 arranged to prevent an axial displacement ? along the longitudinal axis L ? of the filter 41 and of the?further extremity? 34 with respect to the connection fitting 41.

[0063] In a version not illustrated, also the further end? coupling 34 pu? be threaded for screwing to a connection fitting 40 or directly to the branch of the hydraulic system. Alternatively, in another version not shown in the figures, the extremity? coupling 32 pu? include a flange portion like the one described for the? Further end? coupling 34. Alternatively, for the? extremity? of coupling 32 and for? the further extremity? of coupling 34 further types of connection known in the field of hydraulic connections can be used.

[0064] As can be seen from what has been described above, the thermal protection device 10 according to the present invention allows the limitations and drawbacks of the devices of the state of the art to be overcome, successfully achieving the set objects.

[0065] The device according to the invention ? particularly useful for plumbing systems subject to temperature changes, even large ones, such as for example plumbing systems serving solar panels. In fact, the thermal protection device described protects a hydraulic system from damage due to freezing of the heat transfer fluid, allowing it to function correctly in low temperature conditions. There? thanks to the shutter group which allows the evacuation of the water from the hydraulic system when the water is about to freeze. Others? the thermal protection device allows the shutter group to be preserved from possible damage due to the high temperatures that can occur in hot seasons or caused in general by possible overheating of the system.

Claims (15)

1. Thermal protection device (10) suitable for a hydraulic system, comprising a unit? antifreeze valve (20) which includes: to. an antifreeze valve body (21a, 21b) provided with an inlet connection (22) and an? outlet (23) for a heat transfer fluid circulating in said hydraulic system; b. a thermosensitive shutter unit (24) configured to evacuate said heat transfer fluid from said end? outlet (23) upon reaching a minimum threshold temperature cos? to avoid damage to said hydraulic system due to freezing of said heat transfer fluid; characterized in that said thermal protection device (10) also comprises a cooling device (30) arranged to cool said heat transfer fluid and keep it below a maximum threshold temperature so? to protect said heat-sensitive obturator unit (24) from damage, said cooling device (30) being defined by a tubular duct (31), extending along a longitudinal axis (L) and able to be traversed internally by said heat transfer fluid and equipped with one end? coupling (32) configured to couple with said input connection (22) of said unit? antifreeze valve (20), on said tubular duct (31) one or more? elements (33) protruding outwards for the heat exchange of said heat transfer fluid with the external environment. 2. Thermal protection device (10) according to claim 1, wherein said tubular duct (31) and said end? coupling valves (32) are configured in such a way that said tubular duct (31), coupled to said antifreeze valve body (21a, 21b), is positioned with said longitudinal axis (L) oriented transversally with respect to a further longitudinal axis (M) of that unit? antifreeze valve (20). 3. Thermal protection device (10) according to claim 1, wherein said tubular duct (31) and said end? coupling valves (32) are configured in such a way that said tubular duct (31), coupled to said antifreeze valve body (21a, 21b), is positioned with said longitudinal axis (L) aligned, or parallel, to a further longitudinal axis ( M) of that unit? antifreeze valve (20). 4. Thermal protection device (10) according to any one of claims 1 to 3, wherein said tubular duct (31) is hollow cylindrical in shape and extends along said longitudinal axis (L) for a length (A) of between 50 and 100 mm. 5. Thermal protection device (10) according to any one of the preceding claims, wherein said one or more? protruding elements (33) are oriented transversally with respect to said longitudinal axis (L). 6. Thermal protection device (10) according to any one of the preceding claims, wherein said one plus? protruding elements (33) comprise respective annular portions mutually separated and distributed along said tubular duct (31). 7. Thermal protection device (10) according to any one of the preceding claims, wherein the number (n) of said one or more? protruding elements (33) per unit? of length ? between 1 and 4 (n/cm). 8. Thermal protection device (10) according to any one of claims 1 to 5, wherein said one or more? protruding elements (33) define a single helical portion which develops around said tubular duct (31), along said longitudinal axis (L). 9. Thermal protection device (10) according to one of the preceding claims, wherein said one or more? protruding elements (33) comprise respective heat exchange fins. 10. Thermal protection device (10) according to any one of the preceding claims, wherein said one or more? protruding elements (33) are mutually spaced along said longitudinal axis (L) and comprise respective heat exchange surfaces (33a, 33b) capable of being lapped by the air of the external environment to allow heat exchange between said heat transfer fluid and the environment external. The thermal protection device (10) according to claim 10, wherein each heat exchange surface (33a, 33b) has an area of between 100 and 200 mm<2>. 12. Thermal protection device (10) according to any one of the preceding claims, comprising a fitting (40) for the fluid connection of said thermal protection device (10) with a branch of said hydraulic system, said tubular duct (31) comprising an?further extremity? coupling (34) arranged to mate with said fitting (40) so as to receive a domed filter (41) to protect the thermal protection device (10) from mechanical damage and unwanted clogging due to debris, dirt and particles transported by said heat transfer fluid. 13. Thermal protection device (10) according to any one of the preceding claims, wherein said shutter unit (24) comprises a thermosensitive element (25) configured to contract as a function of a drop in temperature so as to allow the passage of said fluid heat transfer fluid inside said valve body (20) and therefore to be evacuated said heat transfer fluid through said end? exit (23). 14. Thermal protection device (10) according to any one of the preceding claims, wherein said shutter group (24) comprises a shutter element (26) provided with one end? hollow (26a) and a? extremity? engagement ring (26b), and an annular sealing element (29) configured to be crossed by said heat transfer fluid, a control portion (25a) of said thermosensitive element (25) being inserted in said end? groove (26a) of said shutter element (26) to make contact with said end? engagement ring (26b) with an abutment surface (29a) of said sealing element (29) to prevent the evacuation of said heat transfer fluid from said end? outlet (23) when a temperature of said thermosensitive element (25) is ? higher than this minimum threshold temperature. 15. Thermal protection device (10) according to any one of the preceding claims, wherein said unit? antifreeze valve (20) includes a cavity? housing (21c) in the shape of a hollow cylinder arranged to house said shutter unit (24) and an inlet opening (22b) for said heat transfer fluid, said shutter unit (24) comprising an elastic element (27) arranged to stress said shutter element (26) towards said end? outlet (23), a contraction of said thermosensitive element (25) - along said cavity? of housing (21c) ? corresponding to a temperature lower than said minimum threshold temperature, causing a disengagement and removal of said shutter element (26) from said inlet opening (22b) to cause the evacuation of said heat transfer fluid through said extremity? exit (23).