EP0047996A2

EP0047996A2 - Protective device for the glass pane of an open hearth fireplace

Info

Publication number: EP0047996A2
Application number: EP81107185A
Authority: EP
Inventors: Hans Georg Fauser
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-09-16
Filing date: 1981-09-11
Publication date: 1982-03-24
Also published as: IT1132960B; IT8024689A0; EP0047996A3

Abstract

The invention relates to a device intended for protecting from the flame action a glass pane mounted on the hearth of a fireplace for the purpose of restricting the flow of air being drawn from the surroundings through the flue under natural draft conditions. The technical problem to be solved is that of providing a simple and economically convenient device which can prevent the glass pane from overheating and blackening over its clear portion owing to the tarry residues of combustion. The solution to the problem is provided by a protective device, which comprises air conveying shaped interspaces adapted to convey air parallel to and in close contact with the glass pane (2) surface facing the fireplace (1) interior, and to create, by virtue of the draft action applied by the flue, laminar airflows which creep along the inner side of the glass pane (2).

Description

This invention relates to a protective device for the glass pane of an open hearth fireplace, and more particularly, to a protective device capable of screening said glass pane from the action of the fire in the fireplace.
As is known, open hearth fireplaces, i.e. fireplaces wherein the flame is fully exposed to view and even directly under reach, serve an unreplaceable function, both from a practical and psychological standpoint, owing to the warm feeling or atmosphere that they create.
However, it has been found that the capacity of such fireplaces to heat the rooms in which they are installed is, lacking special technical expedients, almost non-existent relatively to the amount of heat which they generate. In fact, it may be seen that even though the radiated heat is quite considerable as far as its total amount is concerned, the heating effect is to a large extent wasted to the flue, which draws up a very large volume of heated air from the room where the fireplace is installed; and this hot, or ambient temperature,..air is of necessity replaced by cold air penetrating the building from the outside.
That occurrence is specially substantial in a quantitative sense, to the point that it can be shown that the volume of air drawn from a room through the flue is over twenty times as large as the volume of air required to maintain a correct combustion of wood placed in the fireplace.
Accordingly, in an attempt at improving the heating efficiency of fireplaces, which acquires special importance in times of energy shortage, and at retaining at the same time the fire in full view and fully accessible, which is much appreciated psychologically, glass panes or clear closures have been proposed which can be placed on the hearth of the fireplace such as to hinder the flow of air from the room into the flue without impairing the view and access to the fire itself. In practice, these glass panes comprise one or more plates of tempered glass, which are perfectly clear and heat resistant, connected to the masonry portion of the fireplace such as to be readily raisable, rotatable and removable whenever wood is to be added or adjusted for combustion.
However, the actual use of such glass panes has revealed that while they do achieve the object of preventing heat losses due to air flowing from the room into the flue, they remain unsatisfactory for two different reasons. First of all because very often the glass, even if tempered, cannot withstand the prolonged and high thermal stresses to which it is subjected, so that after a while it breaks. The second reason, and a no less important one, is that the smoke and soot generated by the combustion of wood or the like create within a short time an appreciable tarry deposit on the inner surface of the glass pane, thus reducing, to an at least substantial extent, the possibility of viewing the flame. Thus, one of the most appreciated features of fireplaces is lost, while the user is compelled to perform frequent and laborious cleaning operations.
It is evident that on account of the drawbacks listed hereinabove, the application of such glass panes can only enjoy a limited success, so that much of a fireplace capacity to heat the interiors where it is installed goes lost.
In view of the above situation, and of the objective importance thereof, the task of this invention is to provide a protective device for fireplace glass panes, which can obviate the shortcomings mentioned hereinabove.
Within this task it is an object of this invention to provide a protective device as indicated, which has an extremely simple and economical construction, such that it allows a widespread application of such glass panes to either existing fireplaces or under construction ones.
The aforesaid task and object are achieved according to the invention in that a protective device for the glass pane of an open hearth fireplace, which comprises at least one clear plate removably engaged with the fireplace aperture, also comprises means effective to convey air parallel to and in close contact with the surface of said plate facing the fireplace interior.
Advantageously, said means comprise interspaces shaped as to direct laminar airflows closely along the inner surface of said plate, the air flowing through said shaped interspaces being delivered to the space or room where the fireplace is installed owing to the draft effect of the flue.
Further features and advantages of the invention will be more clearly apparent from the following description of a preferred, though not limitative, embodiment of the inventive device, with reference to the accompanying exemplary drawings, where:

Figure 1 is a front schematic view of a fireplace the hearth whereof is provided with a glass pane incorporating the protective device of this invention;
Figure 2 is a fragmentary sectional view of Figure 1, taken along the line II-II of Figure 1; and
Figure 3 is a sectional view similar to that of Figure 2, showing some constructional modifications of the device.

The protective device according to this invention can be applied to any types of glass panes and fireplace since it is characterized in that means are provided for conveying air in close contact with, or sweeping, the clear surfaces to be protected, and it will be appreciated that such means may be variously constructed, with either natural or forced air circulation, and can be installed directly at the glass pane, or internally, or on the fireplace masonry work. However, the preferred embodiment is that shown in the drawing figures, and contemplates that the air conveying means utilizes the flue natural draft, and that the device is incorporated to the glass pane, without involving the fireplace masonry.
More specifically, a fireplace 1 has a glass pane 2 spanning the entire fireplace width and arranged to be movable relatively to the fireplace 1 by means of control means known per se and adapted, for example, to rotate the glass pane and lift it upwards.
According to the invention, means are provided effective to convey air in close contact with the clear plate 3 of the glass pane, made for example from tempered glass or the like, said means comprising shaped interspaces 4 which extend parallel to the edges of the plate 3 and are so configured as to direct laminar flows of air along said plate 3. In practice, the plate 3 is surrounded and supported by a framework 5, whereat the interspaces 4 are formed, as shown particularly in Figures 2 and 3.
The framework 5 comprises, in fact, and as shown in Figure 2, a first frame 5a and second frame 5b; the first frame 5a can be engaged in substantially airtight relationship with the walls la of the fireplace 1 which border the hearth, and embraces the second frame 5b, in turn surrounding the plate 3. Between the first and second frames, 5a and 5b, there are inserted spacer elements 6 which define the width of the shaped interspaces 4.
The first frame 5a extends prevailingly within the fireplace, thus directing the airflow admitted into the interspace 4 parallel to the plate 3.
Moreover, the first frame 5a may have a folded . edge 7 facing the inner surface of the plate 3 to the fireplace 1. This folded edge defines in practice an air guiding region forming a nozzle-like member convergent toward the plate 3.
The framework 5 shown in Figure 3 is largely similar to the one shown in Figure 2, except that the second frame 5b is missing; in this case, the first frame 5a directly supports the plate 3, through the spacer elements 6.
The plate 3_.is shown in the drawings as being a single piece construction, but it will be appreciated that several coplanar elements may also be provided to make up the plate 3, and each of these elements may also be removable separately from the adjacent ones. In this case, i.e. with a composite construction plate 3, it may be advisable, according to the invention, to provide shaped interspaces also between each plate 3 portions, such as by interposing between contiguous plates T-like elements slightly spaced apart from the plates and arranged to convey air from the surroundings toward the inner surface of each plate portion.
The protective device of this invention operates as follows.
As indicated in Figures 2 and 3 in dotted lines, air from the room or enclosed space where the fireplace 1 is installed is drawn up through the flue and thus forced to flow through the shaped interspaces 4. The latter will be made relatively thin but suitable to establish a somewhat intensified airflow of the laminar type which sweeps across the inner surface of the plate 3, thus cooling it and at the same time preventing the plate to become fouled. In fact, the air being thus conveyed is clean air from the surroundings, and this laminar flow of clean air can also be maintained, if correctly directed, by means of the folded edges 7 in close proximity to the plate 3.
The invention achieves its objects.
A protective device has been in fact provided which also lends itself for extremely simplified and economical applications, such as the ones illustrated, and may be incorporated to any types of existing fireplaces. Moreover, the protective device of this invention is highly effective in operation because its action becomes more powerful the higher grows the flame on the hearth and the stronger the draft through the flue, that is the more its protective action becomes useful.
It should be noted that the device according to the invention provides an airflow which has exactly the opposite effect to those obtainable from a turbulent airflow led into the flue through an aperture having no specific shape.
In fact, any draft induced in the room and directed to flow air toward the flame and flue, would create in the region of the fireplace eddies which also entrain an amount of air mixed with ash particles from the hearth, which results in the formation of tarry deposits at the very areas where turbulent air is admitted, which deposits would quickly affect the plate 3 clearness and blacken it, thus interfering with the radiation of heat as well as with the viewing of the flame.
By contrast, the streamlined airflows created by the device according to this invention flow in close contact with the plate 3 and protect it against the action of heat and tarry deposits by preventing any turbulence.
The invention as described and illustrated is susceptible to many modifications and variations without departing from the scope of the instant inventive concept. As an example, the shaped interspace may be provided at various locations in the fireplace, and the means for conveying the air parallel to the plate may be based upon the principle of air being drawn naturally into the flue under the draft action of the latter and/or provide for a forced draft, e.g. by means of blowers.
Moreover, all of the details may be replaced with other technically equivalent elements.
In practicing the invention, the materials used and the dimensions may be any suitable ones for a specifically selected application.

Claims

1. A protective device for the glass pane of an open hearth fireplace, which comprises at least one clear plate (3) removably engaged with the fireplace (1) aperture, characterized in that it comprises means effective to convey air parallel to and in close contact with the surface of said plate (3) facing the fireplace (1) interior.

2. A protective device according to Claim 1, characterized in that said conveying means comprises shaped interspaces (4) adapted for directing streams of laminar flow air to sweep across the inner surface of said plate (3) in close contact therewith.

3. A protective device according to Claim 2, characterized in that the air flowing through said shaped interspaces (4) is drawn in from the surrounding atmosphere of the room or enclosed space where the fireplace (1) is installed under the action of the flue natural draft.

4. A protective device according to Claim 3, characterized in that said shaped interspaces (4) extend parallel to the edges of said plate (3) and are constructed to direct the related laminar airflow toward the inner surface of that said plate (3).

5. A protective device according to Claim 4, characterized in that said shaped interspaces (4) are provided at the aperture of the fireplace (1) hearth at least between the edges of said plate (3) and the fireplace walls (1a) defining said hearth.

6. A protective device according to Claim 4, and intended for the glass pane of an open hearth fireplace (1) wherein at least one said clear plate (3) and a framework (5) supporting said plate (3) are provided, characterized in that said shaped interspaces (4) are provided at least at said frame.

7. A protective device according to Claim 6, characterized in that said framework (5) is defined by a first peripheral frame (5a) adapted for engagement in substantial airtight relationship with the fireplace walls (la) defining said hearth, and in that said first peripheral frame (5a) supports said plate (3) through spacer elements (6) adapted to promote said laminar airflow.

8. A protective device according to Claim 6, characterized in that said framework (5) is defined by a first peripheral frame (5a) adapted for engagement in substantial airtight relationship with the fireplace sidewalls (1a), and by a second frame (5b) encircling the edges of that said plate (3), and in that said first and second frames (5a - 5b) are held apart by spacer elements (6) and profiled to define said shaped interspaces (4) therebetween.

9. A protective device according to Claim 6 and characterized in that said shaped interspaces (4) provided at least at said framework (5) and spacer elements (6) have the profile thereof defined by said first frame (5a) extending along the surface of said plate (3) facing the fireplace (1) interior.

10. A protective device according to Claim 9, characterized in that said first frame (5a) is formed with an end edge (7) folded toward the inner surface of said plate (3), said folded edge (7) defining an airflow outlet region in the shape of a nozzle.