FR2579302A1 - CATALYTIC HEATING APPARATUS, PARTICULARLY FOR THE COCKPIT OF MOTOR VEHICLES AND BOATS - Google Patents

Abstract

IN A CATALYTIC APPLIANCE, THE OVERALL DIMENSIONS ARE REDUCED AND THE HEAT DISSIPATED BY RADIATION RECOVERED, THANKS TO A MODIFICATION OF THE CATALYTIC PANEL AND AN EXTERNAL ENCLOSURE. BELOW THE SURFACE LAYER OF THE CATALYTIC PANEL 12 IS DIRECTLY ARRANGED THE WALL BOUNDARIES THE COMBUSTION CHAMBER 11. THE ENTIRE CHAMBER 11 IS CONTAINED IN THE HEAT CHAMBER 10.

Description

A 2579302

  Catalytic heating apparatus, in particular

  for the interior of motor vehicles and boats.

  The present invention relates to a catalytic heating device, in particular for passenger compartments of motor cars, truck cabs, boats

and similar uses.

  There are known catalytic type gas heaters in which combustion takes place in the presence of a catalytic panel, so that the

  combustion is complete and flameless.

  In particular, the applicant has already imagined and produced heating apparatuses, especially suitable for the cabs of motor vehicles, essentially comprising a combustion chamber containing a catalytic panel of a type known per se, a gas supply pipe to burn, preferably propane or liquefied petroleum gas, and a heat exchanger through which the air and / or water to be heated by forced circulation is heated by means of the

heat produced by combustion.

  In heaters of this type, there are provided in the heat exchanger, small holes for capillary and organized distribution, of combustion air in the combustion chamber, in particular on surface areas of the catalytic panel which by elsewhere is brought to operating temperature in regime, by an electrical resistance embedded in this panel. Consequently, during start-up, the electrical resistance brings the catalytic panel to the suitable and desired temperature, while in operation at minimum or on standby, it suffices to maintain combustion in a restricted area and

  circumscribed by the catalytic panel.

  To date, the operation of the aforementioned device has always been satisfactory. However, in the field of these heaters, it has always been required that the dimensions be reduced to a minimum, the space available in the cabin of motor vehicles, in particular heavy vehicles, being

very limited.

  Furthermore, even if as already said, the performance of this appliance is essentially satisfactory, a certain amount of heat produced by combustion is dissipated by convection and radiation through the external walls of the combustion chamber, as well as through the underlying wall

to the catalytic panel.

  It is precisely to remedy this last drawback that in known devices, there is provided, below the catalytic layer which consists of a substantially thin support on which the metal or the catalytic compound is deposited, a thick layer. large amount of thermal insulation material such as

Rockwool.

  This obviously results in smaller, non-negligible dimensions which can be further reduced, of the catalytic panel and starting from the assembly of

the heater.

  The main objective of the present invention is therefore to produce a heating device with a catalytic panel which, while retaining the same heating efficiency, has reduced dimensions and makes it possible to recover the heat dissipated by convection and by radiation through the walls of the combustion chamber. This object is achieved by means of a heating device of the type comprising a combustion chamber, one side or wall of which is constituted by a catalytic panel of known type; in this combustion chamber, there is mounted a heat exchanger, preferably with fins, the exterior of which is immersed in the products of combustion, while inside the fluid to be heated, in particular air under pressure, the first means for supplying gas to be burned and second means for supplying combustion air, characterized in that below the catalytic layer, the wall which delimits the combustion chamber is directly disposed, without any 'there is interposition of the thermal insulation layer, and in that the entire combustion chamber is enclosed in a thermal insulation envelope in which air is passed to be preheated under the effect of the heat irradiated by the

walls of the combustion chamber.

  According to a preferred embodiment of the heater according to the invention, the preheated air in the heat recovery envelope is the same as that which is sent to the heat exchanger.

  main heat contained in the combustion chamber.

  According to another aspect of the present invention, the combustion fumes which have ceased to give off heat to the main heat exchanger, are conveyed to the engine of the motor vehicle or of the boat, in particular to the parts of the engine which require

  preheating, to facilitate its cold start.

  According to yet another aspect of the present invention, the electrical preheating resistance of the catalytic panel is replaced by one or more incandescent plugs, of the type well known for igniting diesel engines, which shortens the time required.

  to bring the catalytic panel to ignition temperature

  lytic and therefore to activate the functioning of

the heater.

  Other aspects and advantages of this

  invention will emerge more clearly from the description

  detailed below made with reference to the accompanying drawing in which: Figure 1 is a schematic view from above and in longitudinal section, of the heating apparatus according to the invention, and Figure 2 is a schematic view, in cross section of the appliance of FIG. 1. With reference to the drawing, the heating appliance according to the invention comprises a casing 10 inside which the combustion chamber 11 is mounted, one wall of which is formed by the catalytic panel designated

  as a whole by reference 12.

  The catalytic panel 12 is indeed of the traditional type, for example like that produced and marketed under the name of Termcat from the company Industrie Engerbhard SpA, and comprises a support, for example made of non-woven glass fibers or of another similar material, impregnated with metal or catalytic compound. The support is in turn mounted on a support panel which in this specific case forms a wall

  side of the combustion chamber.

  Unlike traditional construction, however, there is no heat-insulating layer, for example of rock wool, between the support of the catalyst and the panel, which means that the thickness is reduced to values of the order of one fifth. relative to

  traditional catalytic panels.

  In the combustion chamber 11 is mounted a heat exchanger 13 comprising external fins 14 and a bundle of internal tubes 15 through which the air to be heated passes. This air is blown inside the bundle of tubes by a fan 16 and reaches the downstream end of the exchanger 13 in a head manifold 17 which communicates by a pipe 18 for evacuating the hot air in the middle

  to be heated, under the control of a valve 19.

  The evacuation of the combustion fumes produced in the combustion chamber 11 is carried out through an exhaust manifold 20, the downstream end of which can be extended (for example by a flexible pipe) to the engine housing, to preheating it. As is clear from FIG. 1, the air enters the envelope 10 through the peripheral opening 21, moving in the direction of the arrows 22, and therefore licks the external walls of the combustion chamber while heating up by in the heat

irradiated by these walls.

  At the other end of the envelope 10, the preheated air is sucked in by the fan 16 and pulsed in the bundle of tubes of the exchanger 13 where it heats up to the desired temperature, thanks to the

  heat given off by combustion.

  One can however imagine, and this is possible, to use otherwise the preheated air in the space included

  between the casing 10 and the combustion chamber.

  On the other hand, as regards the combustion fumes which are evacuated through the collector, it is possible to increase the speed and the pressure by taking part of the hot air and under pressure leaving the exchanger 13, for example by providing an ejector at the inlet of the collector

evacuation 20.

  It is interesting to note that the air which is reheated is always at a higher pressure than that of the combustion fumes, and that therefore, it is impossible that the latter will flow back and mix with the hot air discharged through the driving

Evacuation 18.

  With regard to the last characteristic,

  above-mentioned tick, namely the replacement of the pre-ignition resistance of the catalytic panel by incandescent candles, we will simply indicate that this replacement is carried out without further details or a detailed graphic representation being necessary. The invention has been described for a preferred embodiment; the fact remains that modifications and variants, equivalent in their design and construction, are possible and can be envisaged without however departing from the scope of

the invention.

Claims (5)

  1. A catalytic heating device of the type comprising a combustion chamber (11) one side or wall of which is constituted by a catalytic panel (12) known per se, a heat exchanger (13) with external fins (14) mounted in said combustion chamber (11) so as to be surrounded by the products of combustion, while inside passes the fluid to be heated, first means for supplying combustion gases, second means for supplying combustion air, characterized in that below the surface catalytic layer of said catalytic panel is directly disposed the wall which delimits the combustion chamber, without the usual layer of heat-insulating material being interposed, and in that the entire chamber of combustion (11) is contained in a heat-insulating envelope (10), forming a space in which the air is passed which will be preheated by the irradiated heat   through the walls of the combustion chamber.   2. Catalytic heating device according to claim 1, characterized in that said fluid to be heated in the exchanger (13) is air and in that in the casing (10) is mounted a fan (16) d air supply inside the exchanger, the suction of this fan being designed so   sucking the preheated air into said space.   3. Catalytic heating device according to claim 1, characterized in that the chamber   combustion chamber (11) communicates with an exhaust manifold   tion (20) of combustion fumes, the downstream end of said manifold communicating with the engine housing vehicle or boat.   4. Catalytic heating device - according to claim 3, characterized in that the exhaust flue collector (20) communicates with the outlet of an ejector supplied by a part   hot air leaving the exchanger (13).   5. Catalytic heating device according to claim 1, characterized in that the panel   catalytic (12) is equipped as preheating means   fage of the panel itself, of at least one incandescent candle   electrically powered descents.