Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60H—ARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
  • B60H1/00—Heating, cooling or ventilating [HVAC] devices
  • B60H1/34—Nozzles; Air-diffusers
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
  • F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
  • F24F13/02—Ducting arrangements
  • F24F13/06—Outlets for directing or distributing air into rooms or spaces, e.g. ceiling air diffuser

Definitions

• the invention relates to a device for partially closing the end of a hot air blowing pipe.
• This type of pipe is used in particular in vehicles or vehicles to carry hot air to ensure the heating compartment in which the driver and / or his passengers take place.
• the invention more specifically relates to a particular design of this type of partial closure device, also commonly called “grid”, intended to improve the safety of people operating in the driving compartment.
• the hot air blowing lines fitted to the vehicles are connected to a blowing or ventilation system which, in connection with a source of heat, makes it possible to blow air at a temperature sufficient to ensure the comfort of the driver and the passenger.
• JP 61 94 250 discloses a grid structure whose fins are orientable, so as to deflect the hot air flow in the desired direction.
• a problem that the invention seeks to solve is that for high air-blowing temperatures, typically greater than 100 ° C., the grid disposed at the mouth of the pipe rapidly reaches the temperature of the air which the crossing. This temperature can therefore be a danger for people likely to touch the grid.
• the heating of the cabin is provided by blowing air at a temperature typically between 110 and 120 ° C.
• the hot air blowing duct generally opens into the rear of the cab, behind the driver's seat.
• additional protections are generally provided to form obstacles and prevent direct access to the grid.
• the installation of these obstacles increases the overall size of the heating device, and is therefore not really satisfactory.
• JP 61-161 358 discloses an outlet grille of a vehicle air conditioning duct, which is equipped with a liquid crystal-based film whose color changes with the temperature. This film is placed on the visible side of the scale, and adopts a color that corresponds to the temperature of the grid, which is itself the temperature of the air passing through it.
• the object of the invention is therefore to prevent any risk of burns, by exposure of an apparent surface of the grid to a high temperature, of the order of the temperature of the hot air blown .
• the invention therefore relates to a partial shutter device of an end of a hot air blowing duct. In known manner, this device comprises a plurality of through openings pierced in its thickness.
• the device has arrangements capable of generating a temperature drop greater than a predetermined threshold between its face facing the inside of the pipe and its exposed face outside the pipe, and this when the driving is traversed by a flow of air at a temperature greater than a predetermined value relative to the ambient temperature.
• the invention consists in designing the grid so that its accessible outer surface remains at a temperature that does not present a danger for people likely to touch it. This arrangement therefore makes it possible to benefit from a large heating power, with a blown air at a very high temperature, and this while reducing the bulk of the blowing device, since it is therefore not necessary to provide a device. specific protection preventing access to the grid.
• the grid according to the invention has a thermal behavior which substantially reduces the temperature of the accessible surfaces, while allowing blowing at a high air temperature.
• the determination of the geometry of the grid, and the choice of the thermal conductivity of the material constituting it make it possible to define the temperature difference between the internal face of the grid, which is at the temperature of the blown air. , and its outer face, which is in contact with an atmosphere at room temperature.
• This thickness corresponds substantially to the length of the through openings in which the flow of air will pass.
• the temperature on the apparent face of the grid may not be totally homogeneous. It is therefore possible to play on the distance separating the adjacent through openings to prevent the appearance of hot spots on the outer surface of the grid.
• the openings are sufficiently distant from each other.
• the gate surface in contact with the outside serves to dissipate the heat towards the outside.
• Distance between the openings means the smallest distance between two points of two adjacent openings, in the case where these openings are not rectilinear and parallel.
• S is the surface of the portions separating the adjacent openings
• the surface of the portions separating the openings is determined according to their geometry.
• the desired temperature drop is a function of the temperature of the supply air, the ambient temperature, and the temperature considered acceptable for safety reasons.
• the blown air is frequently at a temperature greater than 80 ° C. with respect to the ambient temperature, namely at a temperature of the order of 110 to 120 ° C.
• the through openings may advantageously flare outward, for example by having a connecting bevel with the face of the grid exposed outside the pipe.
• the channels forming the through openings are slightly wider at their outlet, so that the flow of hot air does not lick the end of the channel.
• a similar effect can be achieved by making an internal groove inside the openings near the outlet of the openings. In this way, this lack of material at the end of the channel causes a disturbance in the propagation of heat, from the hot zone of the grid located on the inner side of the pipe, to the cold zone, located on the outer part.
• the openings with a certain directivity, to ensure a deflection phenomenon.
• This deflection can be made adjustable by making the portions separating the mobile and in particular pivoting openings according to conventional designs.
• FIG. 1 is a summary perspective view of a grid according to the invention.
• Figure 2 is a cross-sectional view of a grid shown mounted at the end of a hot air blowing duct.
• Figure 3 is a cross-sectional view of a grid made according to an alternative embodiment.
• Figures 4 to 7 are front grid views corresponding to different variants of shape and geometry of their openings.
• the grid (1) according to the invention is in the form of a pierced part of a plurality of through openings (2), connecting the face ( 3) of the grid oriented inside the blowing pipe (4), and the outer face (5), accessible from the outside.
• This grid (1) can be indifferently mounted directly at the outlet of the pipe (4), or be mounted on the support (7).
• the openings (2) have a width ()), and are
• the width (Jt) of the openings (2), and the number of the latter is determined so that the air passage area is sufficiently high, to avoid increasing too much the speed of air to the output of the grid.
• the width (Jt) of the openings is also chosen to provide the protection function and block the passage towards the inside of the pipe (4).
• the thickness (d) of the portions (8) separating the openings (2) is large enough to avoid creating hot spots on the outer face (5) of the grid.
• the air blown through the pipe (4) is at a high temperature, of the order of 120 °, and it is desirable, even imposed by certain regulations in force, that the outer surface (5) of the grid has a temperature in any point below 80 ° C.
• the temperature of the outer surface (5) is less than 70 ° C., because the feeling of burn is more noticeable on metals.
• the gate (1) is made of a material which has a thermal conductivity ( ⁇ ) which is low, and typically less than 0.2 W / mK. This value of thermal conductivity can be chosen as a function of the desired temperature difference between the blown air and the surface temperature.
• the grid may be made of a homogeneous material, or by stacking several elementary layers of different materials, depending on the direction of flow. It is also possible to include a layer of air between two elementary layers. In the case of such a sandwich structure, the thermal conductivity of the gate is calculated as being the overall conductivity of the set of elementary layers, calculated in the direction of flow of the airflow, according to the usual techniques. .
• 35 mm has openings with a width ()) of about 10 mm, separated by solid portions (8) of a thickness (d) of the order of 10 mm also. These openings have a height (h) of 90 mm.
• the material used has a thermal conductivity ( ⁇ ) of the order of 0.1 W / mK.
• the criterion (G) previously defined in this particular case is therefore calculated by taking into account the area of the portions or fins (8) separating the openings, equal to hxd is 9 cm 2 , and the thickness (e) of the grid .
• the criterion G is ⁇ xhxd / e, ie 2.57.10 "3 W / K.
• the surface temperature measured on the whole the outer face (5) of the grid does not exceed 80 ° C.
• the measurement can be done by thermocouples or PT100 type platinum probes, which are standard measurement systems.
• This temperature drop of 4O 0 C avoids any risk of burn, so that such a grid meets the requirements of the European Directive 2001/56 / EC on the heating systems of the passenger compartment of motor vehicles.
• the openings (20) may have, on the side of the outer face of the grid, an opening (23). flared, defined by chamfers (22) at the edges of the portions (21) separating the openings (20).
• the openings (30) may have near the outer surface (5), grooves (31) or more generally a whole recess of material which disturbs the propagation of the heat from the inner face (3) towards the outer face (5) of the grid.
• the grid (40) may be of a generally circular shape, intended to be placed at the end of a cylindrical pipe.
• the openings (41) may be either substantially longitudinal, as shown in FIG. 4, or else polygonal, and for example octagonal (51) or hexagonal (61) as illustrated respectively in FIGS. 5 and 6.
• the distance between the openings (51, 56) is defined as the shortest distance between two points of two openings.
• these profiles (72) can be hyperbolic, to optimize the propagation of heat according to the principles known in thermal calculations. This improves the homogeneity of the temperature of the outer face of the grid.
• blow pipe closure grids according to the invention have the major advantage of limiting the temperature of the surfaces exposed to a contact. The risk of burns are therefore canceled, or at least particularly reduced.
• the invention can find a very particular, but not exclusive, application in the equipment of heating devices installed on motor vehicles, in particular of public works machinery, and more generally in any compartment likely to receive people. and in which opens a hot air blowing pipe.

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• 2004
  • 2004-12-21 EP EP04816588A patent/EP1831041A1/de not_active Ceased
  • 2004-12-21 WO PCT/FR2004/050741 patent/WO2006067284A1/fr active Application Filing

Non-Patent Citations (1)

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