Improved plate shield for probes

Abstract

The invention is a plate shield (100) of the passive type for probes, comprising a plurality of plates (120), wherein between at least two of said superimposed plates (200) there is a disc or annular surface (300) directly or indirectly joined to the plate (200) located above it, so as to define with the latter a toroidal chamber (310) surrounding a measurement cavity (140), and wherein said toroidal chamber (310) is closed towards said measurement cavity (140) and comprises an opening (330) facing outwards.

Description

[0001] IMPROVED PLATE SHIELD FOR PROBES

[0002] DESCRIPTION

[0003] The present patent concerns plate shields for environmental parameter measurement probes, and in particular it concerns to a new improved plate shield.

[0004] Thermometer shields of the type with plates, also referred to as “gill plate radiation shields”, are known. These shields consist of a plurality of horizontal superimposed plates spaced from one another, shaped and perforated in such a way that a measurement cavity, in which a probe, for example a temperature probe, is housed, can be defined within the plate stack. The plates make it possible to protect the probe from weather agents and direct radiation, while the distance between the plates ensures ventilation in the cavity, so as to avoid overheating that would affect measurements.

[0005] Plate shields are known in which the plates have various configurations intended to maximise ventilation, that is, the speed of the air which flows between the plates through the cavity and comes into contact with the probe. For example, plate shields are known which are provided with a lower opening to maximise internal ventilation, but which do not prevent heat and radiation from rising upwards from below, particularly when solar radiation is higher or in the presence of snow which reflects sunlight.

[0006] Shields are also known in which the plates, instead of being substantially circular in shape and of being arranged parallel to each other, are configured in such a way that a sort of ventilation channel arranged as a spiral around the measurement cavity is defined between them.

[0007] However, in all the plate shields of the known type ventilation is insufficient in the absence of wind, that is, with air speeds lower than 1 m / s. In these conditions, and especially in the presence of solar radiation, ventilation inside the shield is not sufficient to prevent the air in the measurement cavity from overheating, which leads to non-negligible errors in ambient temperature measurements.

[0008] It is known that, to solve the problem described above, ventilated shields are used, that is, shields equipped with a cooling fan suited to ensure proper ventilation inside the measurement cavity.

[0009] However, said systems, which also require devices to power the fan, are clearly more complex and need more maintenance than passive shields, that is, shields that do not require forced ventilation, involving higher overall costs.

[0010] In order to overcome all the above-mentioned drawbacks, a new passive plate shield for probes has been designed and manufactured, which is configured to maximise ventilation even when there is no wind.

[0011] The main object of the present invention is to maximise ventilation in the measurement cavity in the absence of wind, that is, with wind speeds even lower than 0.2-0.3 m / s.

[0012] Another object of the present invention is to provide a shield that does not require any forced ventilation device, which results in lower construction, installation, operation and maintenance costs.

[0013] These and other direct and complementary objects are achieved by the new plate shield for probes which comprises, in its main parts: a top unit, that is, an upper covering unit in turn made up of at least one plate and more preferably of at least two plates arranged on top of and spaced from each other in such a way as to define a ventilation gap between them; a plurality of plates arranged on top of and spaced from each other, under said top unit, each of said plates having substantially concave cross section and being arranged with their concave surface facing downwards, and a central opening that, together with the other plates, defines the measurement cavity where at least one probe will be positioned, wherein said probe can be a temperature probe, a temperature-humidity probe, a humidity probe or another type of probe suitable for the measurement of environmental parameters requiring the correct temperature in the measurement cavity.

[0014] The upper surface of each plate, that is, the surface intended to face upwards, is reflective, so that it can shield radiation from above, typically solar radiation.

[0015] The underside of each plate, that is, the surface intended to face downwards, is coated with or made of a material suited to absorb the light reflected by the underlying plate. Thanks to this configuration, the fraction of light that is reflected towards the inside of the shield is absorbed by the plate above, so that the absorbed heat is retained outside the central cavity.

[0016] Under at least one of said plates, in the gap between two superimposed plates, there is at least one annular surface, preferably substantially flat and provided with a central opening in a position corresponding to that of said central opening of the plates.

[0017] Said annular surface is thus positioned in such a way that, together with the underside of said plate, it defines a sort of toroidal chamber around said cavity for the probe, wherein said toroidal chamber is closed along its entire inner perimeter, meaning that it is not in communication with the inside of said cavity, while it is open along its outer perimeter, meaning that it is in communication with the external environment.

[0018] Said toroidal chamber substantially serves as a storage chamber for the air that is heated by the light reflected and absorbed by the underside of the plate. In this way, the heated air does not reach the measurement cavity, but bypasses it and then flows towards the outside thanks to the natural ventilation between the plates.

[0019] Furthermore, the presence of the annular surface reduces the gap between two superimposed plates, thus maximising the air speed due to the Venturi effect and consequently ventilation in the measurement chamber.

[0020] Furthermore, according to the invention, the central part of each plate has a substantially S-shaped cross section, as better illustrated with the aid of the drawings, which facilitates the inflow, passage and outflow of air, again with the aim of improving ventilation in the measurement cavity.

[0021] Moreover, according to the invention, the new shield comprises a closing partition positioned at the base, so as to hinder the effects of radiation and the rise of heat from below towards the inside of the measurement cavity.

[0022] The solutions adopted, and described above, taken individually and combined with one another, help ensure proper ventilation in the shield, in such a way as to limit measurement errors in the measurement chamber, which are essentially due to radiation. In addition, these solutions help protect the inside of the cavity from the influence of external radiation, again with the aim of minimising measurement errors. To guarantee these results, the shield must be conveniently positioned, so that said plates and said annular surfaces are horizontal, which favours the passage of air from all directions.

[0023] The characteristics of the new shield for thermometers are better clarified in the following description, making reference to the drawings, which are attached by way of non-limiting example.

[0024] Figure 1 shows a vertical sectional view of the new shield (100), while Figure 2 shows a partial sectional view thereof. Figure 3 shows a detailed sectional view of two superimposed plates (200), each with an underlying annular surface (300).

[0025] The new shield (100) comprises a top unit (110) intended to be positioned facing upwards, said top unit (110) in turn comprising one or more covering plates (120) arranged on top of and spaced from one another, so as to form ventilation gaps (130).

[0026] Each covering plate (120) is substantially concave in shape, with its concave surface facing downwards and no opening, to ensure complete shielding against radiation from above.

[0027] Said covering plates (120) are made of or coated with a highly reflective material.

[0028] In the example shown in the figures, the shield (100) comprises three of said covering plates (120).

[0029] The shield (100) also comprises a plurality of plates (200) arranged on top of and spaced from each other, so as to define ventilation gaps (210) between them. Each of said plates (200) has a central opening (220), so that the stack of superimposed plates (200) defines a cavity (140), or measurement cavity, intended to contain at least one probe (150), for example a temperature probe. The plates (200) and the covering plates (120) are rigidly constrained to one another by means of a fixing structure comprising, for example, pins (160) inserted all through the plates (200, 120). The structure can also comprise a column (170) or another means suited to support said shield (100).

[0030] Each plate (200) comprises an upper surface (230), meaning a surface intended to face upwards, and an opposite underside (240).

[0031] Said upper surface (230) is made of or coated with a reflective material, that is, a material capable of maximizing the radiation reflection, while said opposite underside (240) is made of or coated with a material capable of maximizing the absorption of light and thus of the heat reflected by the underlying plate. For example, said underside (240) is made of a black opaque material.

[0032] The upper surface and the underside (230, 240) can be made of layers of materials fixed together, for example obtained through overmoulding.

[0033] The configuration of each plate (200) is thus constituted by a central opening (220) and a substantially S-shaped annular part (250), that is, a part comprising a concave annular portion (251) with its concave surface facing downwards and a central annular portion (252) substantially flattened and connected to said central opening (220). Said configuration favours the inflow, passage and outflow of air through the gaps (210), that is, better ventilation.

[0034] Under said underside (240) of at least one or preferably of each plate (200) there is an annular surface (300) comprising a substantially flat annular surface arranged facing said concave annular portion (251), so as to define with the latter a sort of toroidal chamber (310), open towards the outside of the shield.

[0035] The figures show how said annular surface (300) is joined to the plate (200) above it forming a single body, but it is not excluded that said annular surface (300) can in any way be constrained in the gap (210) between two superimposed plates (200).

[0036] The opening (330) of said toroidal chamber (310) is therefore defined between said annular surface (300) and said underside (240) of the plate (200) above it, and is recessed with respect to the perimeter (260) of the superimposed plates (200).

[0037] Said toroidal chamber (310) has the function of collecting the heat absorbed by said underside (240) of the plate (200) and produced by the reflection of the sunlight incident on the upper surface (230) of the underlying plate (200). The heat is then collected in said toroidal chamber (310) and flows outwards, actually bypassing the measurement cavity (140) without affecting the temperature measurement.

[0038] The presence of said annular surfaces (300) also reduces the space (320) between the annular surface (300) and the underlying plate (200), resulting in aerodynamic compression of the air, whose speed inside the measurement cavity (140) is thus increased by the Venturi effect.

[0039] Said space (320) is preferably larger than the opening (330) between said annular surface (300) and the plate (200) above it, so as to achieve the synergistic effect of collecting heat in the toroidal chamber (310) without limiting the horizontal ventilation flow in the measurement chamber (140), but rather maximising its speed. In fact, it has been experimentally verified that the solution described above is particularly effective in conditions of low or no wind, in which the known shields with natural ventilation have important limitations. In any case, this solution makes it possible to maximise ventilation and reduce the influence of external radiation on the temperature in the measurement cavity (140).

[0040] Furthermore, according to the invention, the shield (100) comprises at least one bottom closing plate (400) arranged at the base of said stack of plates (200) in such a way as to prevent or, in any case, limit radiation from below and the upward flow of heat from below.

[0041] Said annular surface (300) can be made of a plastic or metallic material or combinations of plastic and metallic material, coupled in any way, and has a limited thickness, preferably of approximately 1 mm, if made of plastic or a composite material, or even less, if made of a metallic material.

[0042] According to the invention, for example, the annular surface can be provided with a partial or complete perimeter band, partially or completely metallic, characterized by high thermal conductivity. In this way, the portion exposed to the heating action produced by solar radiation, especially that reflected from below (both from the ground and from the underlying surface), can quickly transfer the absorbed heat to the opposite, cooler portion, favouring effective heat dissipation away from the measurement chamber. This makes it possible to improve the cooling of the heated annular area, minimising the influence of direct and reflected radiation on the temperature measured by the shield.

[0043] In the solution shown in Figures 1, 2 and 3 said annular surface (300) is intact, with no openings. In a useful alternative solution, said annular surface (300‘) is provided with one or more openings, for example distributed and configured as represented in Figure 4, which shows a three-dimensional view of the annular surface (300’) only.

[0044] The presence of one or more openings, which are described in greater detail below, helps improve the performance of the shield when used in particular environments or weather conditions or, more specifically, on snow-covered and / or icy surfaces, or in any case where there is significant reflection of sunlight from below and at such angles that the reflected radiation (R) reaches the space between the plates, hitting the underside (301) of the annular surface (300), as schematically shown in Figure 5.

[0045] In this situation, the heat absorbed by the annular surface (300) would be spread towards the inside of the shield, thus affecting the temperature measured inside the measurement cavity (140).

[0046] According to the invention, to limit the effect described above, said annular surface (300') comprises one or more openings (340), for example and preferably in the form of slits distributed along a circumference, which serve the function of interrupting the continuity of the annular surface (300) itself, thus hindering heat diffusion towards the inside of the measurement chamber (140).

[0047] More specifically, as shown schematically in Figure 6 and in detail in Figure 6a, the heat accumulated on the perimeter part (341) of the annular surface (300) can be dissipated through said slits (340), since the hot air (H) which comes into contact with said perimeter part (341) will tend to rise, entering said toroidal chamber (310) through said slits (340) and then flowing outwards as previously described. In this way, the influence of any reflected radiation (R) on the temperature inside the measurement chamber (140) is minimised.

[0048] In addition, as schematically shown in Figure 7, any reflected radiation (Rl) with an even greater angle, which could be incident on the annular surface (300) inwards, meets instead said openings (340), directly penetrating into said toroidal chamber (310), where the generated heat can be dissipated.

[0049] Figure 4 shows that said openings (340) are in the shape of slits distributed along a circumference, actually separating a perimeter part (341) of the annular surface (300) from an inner part (342), these being joined together by means of partitions (343). According to the invention, the number, distribution and dimensions of said openings (340) are established in such a way as to minimise heat transmission between said perimeter part (341) and said inner part (342). For this purpose, the dimensions of said joining partitions (343) can be kept to a minimum.

[0050] In alternative solutions that are not illustrated herein, said openings (340) can, however, have different shapes, sizes and distributions, always with the aim of minimising heat transmission towards the inside of the measurement chamber (140), favouring instead the rise of hot air towards the inside of the toroidal chamber (310).

[0051] For example, said openings can be in the form of small holes, for example holes with a characteristic diameter of a few millimetres, distributed over the entirety or part of said annular surface (300), even on its perimeter part (341). The presence of said openings (340) on said annular surface (300) reduces the compression of the air flowing between an annular surface (300) and the underlying plate (200), but this effect is nevertheless largely offset by the advantages deriving from heat dissipation towards the toroidal chamber (310), especially on highly reflective surfaces (such as light-coloured, sandy, snow-covered surfaces, etc.) and in the presence of highly inclined radiation. In any case, it has been found that even in the presence of grassy or moderately reflective surfaces, or in any case with relatively little radiation from below, the presence of the slits has no appreciable negative effect on the performance of the shield.

[0052] Therefore, with reference to the above description and the attached drawings, the following claims are made.

Claims

CLAIMS1. Plate shield (100) of the passive type for probes, comprising a plurality of plates (120) arranged on top of one another and spaced apart in such a way as to define ventilation gaps (210) between them, each of said plates (200) being provided with a central opening (220) so that the stack of superimposed plates (200) identifies a measurement cavity (140) intended to contain at least one probe (150), characterized in that between at least two of said superimposed plates (200) there is an annular surface (300) directly or indirectly joined to the plate (200) located above it, so as to define with the latter a toroidal chamber (310) surrounding said measurement cavity (140), and wherein said toroidal chamber (310) is closed towards said measurement cavity (140) and has an opening (330) facing outwards.

2. Shield (100) according to claim 1, characterized in that at least one of said plates (200) comprises an upper surface (230), that is, a surface intended to be facing upwards, made of or coated with a reflective material, that is, a material capable of maximizing the radiation reflection, and an opposite underside (240) made of or coated with a material capable of maximizing the absorption of light and thus of the heat reflected by the underlying plate, and more preferably said lower surface (240) is made of a black opaque material.

3. Shield (100) according to claim 1, characterized in that the configuration of one or more of said plates (200) is constituted by a central opening (220) and a substantially S-shaped annular part (250), that is, a part comprising a concave annular portion (251) with its concave surface facing downwards, and a central annular portion (252) substantially flattened and connected to said central opening (220).

4. Shield (100) according to one or more of the preceding claims, characterized in that said annular surface (300) faces said concave annular portion (251) of the plate (200) located above it, and wherein said opening (330) of said toroidal chamber (310) is defined between said annular surface (300) and said underside (240) of the plate (200) located above it, and is recessed with respect to the perimeter (260) of said superimposed plates (200).

5. Shield (100) according to one or more of the preceding claims, characterized in that the space (320) through which air flows, between an annular surface (300) and the underlying plate (200), is reduced compared to the gap (210) between two superimposed plates (200) and is preferably larger than said opening (330) of the toroidal chamber (310).

6. Shield (100) according to one or more of the preceding claims, characterized in that it also comprises a top unit (110) positioned on top of said plurality of plates (200) and in turn comprising one or more covering plates (120) arranged on top of one another and spaced apart in such a way as to define ventilation gaps (130), said covering plates (120) being made of or coated with a highly reflective material.

7. Shield (100) according to one or more of the preceding claims, characterized in that it comprises at least one bottom closing plate (400) arranged at the base of said stack of plates (200) in such a way as to prevent or, in any case, limit radiation from below and the upward flow of heat from below.

8. Shield (100) according to one or more of the preceding claims, characterized in that said annular surface (300‘) comprises one or moreopenings (340) distributed in any way on the entirety or part of said annular surface (300’).

9. Shield (100) according to claim 8, characterized in that said one or more openings (340) are in the shape of slits distributed along a circumference that separates a perimeter part (341) of said annular surface (300') from an inner part (342) of the same.

10. Shield (100) according to claim 8, characterized in that said one or more openings (340) are in the shape of holes distributed on the entirety or part of said annular surface (300'), also on the perimeter part (341) of the latter.

11. Shield (100) according to one or more of the preceding claims, characterized in that said annular surface (300) is provided with a partial or complete perimeter band, partially or completely metallic, characterized by high thermal conductivity.

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