Fan heater

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The invention concerns a fan heater for temporary heating of a building site, including a fan, for transporting air through the fan heater from an inlet to an outlet, and at least one heating element for heating the air passing through the fan heater.

PRIOR ART

[0002] Heating of spaces during building is often necessary, especially before the permanent arrangements for heating, such as radiators and the like, have been installed. The benefits of heating are several. The comfort and working conditions of the workers on the building site will improve. The necessary conditions for using certain building materials, such as paints, glues etc. will be ensured. The humidity in the recently cast concrete or recently applied mortar, cement or plaster will also be reduced by heating the space, thus preparing it for further steps in the building process or interior decoration.

[0003] There exist a vast number of heating arrangements of various types for building sites. Fan heaters are among the most common. In general the function thereof is as follows. Cool air is drawn into the heater by a fan. The air passes by heating elements, which are arranged downstream of the fan, and its temperature is thereby increased, before the air is expelled by the action of the fan.

[0004] In order to accomplish a high heating effect, both the fan and the heating elements must have a large capacity. However, this desired effect results in a bulky construction, especially in the axial direction of the fan, which coincides with the air stream through the fan heater, since both the size and number of heating elements arranged downstream of the fan are increased.

[0005] Another consideration is that the outside surface of the fan heater must not be too hot. A suitable temperature of the casing is determined by acceptable temperatures in order to avoid risks of burn injuries to humans and of fire hazards. The temperature restrictions also tend to make the fan heaters bulky, since the volume needs to be increased in proportion to the power increase in order to keep the outside surfaces at an acceptable temperature.

[0006] DE 4330878 discloses a fan heater with a fan and a heating element. The heating element is arranged close to the front outlet of heated air. The heating element comprises a number of PTC heaters. The number of PTC heaters in use may be varied. A thermosensor may be employed for regulation of the temperature.

[0007] While it would not be particularly difficult to make larger fan heaters, such heaters are difficult to handle and use. A fan heater which is too large and heavy to carry manually could be supplied with castors for rolling the heater, but it will still have to be able to pass through doorways and narrow passages, as well as be able to turn around corners where space is limited.

PROBLEM STRUCTURE

[0008] The present invention has for its object to attain a fan heater with a large power output, while its size and the temperature of its outer surfaces are limited.

SOLUTION

[0009] The object forming the basis of the present invention will be attained if the fan heater referred to initially is characterized by the features of the independent claim.

[0010] Further advantages will be apparent from the dependent claims.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0011] The present invention will now be described in greater detail hereinbelow, with reference to the accompanying drawings. In the accompanying drawings:

Fig 1 shows a perspective view of a fan heater according to the invention;

Fig 2 shows a perspective view of the fan heater from the opposite side;

Fig 3 is a schematic side view of the fan heater, where an outer side panel and an inner guiding plate have been removed; and

Fig 4 is a perspective view of heating elements and guiding plates included in the fan heater according to the invention.

PREFERRED EMBODIMENT

[0012] Figure 1 shows an overview of a fan heater 1 according to the invention. The fan heater 1 has an inlet 2 for cool air on its side turned away from the viewer and an outlet 3 for heated air arranged on top of the fan heater 1. The outlet 3 is designed to distribute the air in different directions, but it is not essential for the invention, and could be replaced by any other outlet known in the art, as long as it is able to withstand the temperature of the heated air.

[0013] For the ease of transporting the fan heater, it is provided with castor wheels 4 and a handle bar 5 so that it may be steered in any direction manually. For the ease of handling and using the fan heater 1, one or more of the castors 4 is lockable. Also, the handle bar 5 is preferably made in a material which has a high heat capacity, i. e. its temperature will remain reasonably low despite long-term use of the fan heater, so that it may be touched without the risk of burning.

[0014] Next to the handle bar 5 there is an electrical connection device 6, which may be connected to a suitable electrical outlet. The connection device 6 should conform to the standards which are applicable on the markets where the fan heater 1 is sold, and hence many variations thereof are possible. The fan heater 1 is designed for a considerable electrical power, yet its design is notably compact, in relation to the output power.

[0015] In figure 2, the fan heater 1 is viewed from its opposite side, with the air inlet 2 facing the viewer. An external filter of conventional design has been removed from the inlet side of the fan heater. The purpose of the external filter is to prevent dust and debris from being sucked into the fan heater 1, which could damage the internal parts of the fan heater 1, at least in large amounts. Another advantage is that the working environment on the building site will improve, since the filter will trap the dust and keep it from whirling around in the air.

[0016] Figure 2 reveals that an inner grille 7 is arranged in front of a fan 8 inside the fan heater 1. There is an approximately circular opening 9, through which the blades 10 of the fan 8 are visible. The fan 8 draws air into the fan heater 1, and transports it through the fan heater to the outlet 3.

[0017] The fan 8 is a cylindrical fan, the blades 10 of which rotate around a central axis 11. The air is drawn into the fan 8 from one end of the cylinder constituting the outer shape of the fan 8, in an axial direction, approximately parallel with the central axis 11 of rotation. The blades 10 of the fan 8 are angled so that they direct the air in a radial direction from the central axis 11. The air will be let out from the fan 8 through the envelope surface of the cylinder circumscribing the fan 8.

[0018] In the preferred embodiment, the diameter of the fan 8 is of the same magnitude as its axial length. The outlet of air is distributed over the axial length of the fan 8.

[0019] The schematic side view of figure 3 gives a better overview of the cylindrical fan 8, which is seen from the side in this view. The outer side plate of the casing and one inner guiding plate have been removed from the drawing for clarity. A number of heating elements 12 are also seen from the side, arranged around at least a part of the envelope of the cylindrical fan 8. As air is let out from the fan 8 radially, it will move past the heating elements, and will be heated to a high temperature. The heating elements 12 are distributed along the cylindrical fan 8, thus ensuring a reasonably even and efficient heating of the air. At the same time, the interior space of the fan heater 1 is used efficiently, and the heating elements 12 do not add to the axial length of the fan heater, as they are arranged on the outside of the cylindrical fan 8 in its radial direction.

[0020] The heating elements 12 according to the invention have the general shape of a U, with the shanks of the U electrically connected at the bottom. The rounded part of the U is arranged around the cylindrical fan 8 on its outside, so that the air expelled from the fan 8 has to pass the heating elements 12. Since the heating elements 12 follow the outer shape of the fan 8, the additional space needed for the heating elements 12 in the radial direction of the fan 8 is minimal.

[0021] Since there are several heating elements 12 arranged in the axial direction of the cylindrical fan 8, the space around the fan 8 is also used efficiently for heating the air coming out from the fan 8. The heating elements 12 are approximately uniformly arranged across the outer envelope surface of the cylindrical fan 8 in the axial direction.

[0022] Another aspect of the arrangement of the heating elements 12 is that there are several layers of heating elements 12 arranged in the radial direction of the cylindrical fan 8. This is difficult to see in figure 3, but will be apparent from figure 4. In this way the air from the fan 8 will pass by a number of heating elements 12, before it reaches the outlet 3. The increased number of heating elements 12 will further increase the turbulence in the airflow from the fan 8, thereby further increasing the contact of the air with the heating elements 12 an further increasing the efficiency of the heating of the air. In other words there will be an increased heating power.

[0023] To this effect, there is also arranged a diffusor 14 above the heating elements 12 and between the two guiding plates 13, whereof one plate is removed from the drawing for clarity.

[0024] Figure 4 shows a detail view of the heating elements 12 surrounding the cylindrical fan 8. In the figure two guiding plates 13 are arranged on either side of the heating elements 12. Between the two guiding plates 13 and above the heating elements 12, the diffusor 14 is clearly visible.

[0025] In figure 4 it is clear that the heating elements 12 are U-shaped and arranged in several rows in the axial direction and in several layers in the radial direction. The outermost heating elements 12 have a longer radius of curvature than the inner heating elements 12, and their radii of curvature are gradually less, with the innermost heating elements 12 having the least radius of curvature. The innermost heating elements 12 closely follow the curvature of at least half of the circumference of the cylindrical fan 8.

[0026] All the heating elements 12 have their electrical connections at the bottom, which means that the provision of electrical wires in the fan heater 1 will be simplified.

[0027] On both sides of the heating elements 12 there are guiding plates 13, as briefly mentioned above. The guiding plates 13 serve to guide the air flow from the fan 8 towards the outlet 3. The guiding plates 13 also deflect the air flow from the side plates of the casing, thereby keeping them as cool as possible. The material of the guiding plates 13 may in some embodiments be able to reflect the heat inwards. In some embodiments, a layer of insulation may also be provided between the guiding plates 13 and the outer side plates.

[0028] Although some of the air expelled from the cylindrical fan is initially not directed towards the outlet 3, the provision of the guiding plates 13 will make sure that the air flow is directed upwards eventually. Air which is deflected back towards the heating elements 12 by the guiding plates 13, will be heated further, and will thereby have an increased tendency to rise towards the outlet 3.

[0029] Air moving upwards from the fan 8 will first pass and be heated by the heating elements 12, and its turbulence will be increased thereby. Some of the air will be deflected by the guiding plates 13, as described, and will be heated further. Air rising straight upwards, after passing the heating elements 12 at least once, will encounter the diffusor 14, and will be directed either back to the heating elements 12, directly or via the guiding plates 13, or to the sides, where it passes between the diffusor 14 and the guiding plates 13. In both cases its turbulence will increase, while its velocity of flow decreases.

[0030] The arrangement of the heating elements 12 around the fan 8 and the arrangement of the guiding plates 13 and the diffusor 14, to direct the air flow, cooperate to realize the compact fan heater 1 with a high heating power.

ALTERNATIVE EMBODIMENTS

[0031] While the embodiment shown in the drawings has a particular type of outlet 3, its shape is not essential for the invention. Any other type of outlet arrangement may be used, but an outlet arranged on the upper part of the fan heater will be preferred, in order to make the best use of the effects from heated air rising upwards.

[0032] In the preferred embodiment, U-shaped heating elements 12 have been used. They may be replaced by heating elements with other shapes, more or less circumscribing the cylindrical fan, ie. Ω-shaped elements, spirals, or loops.

[0033] Other arrangements of the heating elements 12, for covering the majority of the axial length of the cylindrical fan 8, are envisaged, such as arranging the heating elements 12 in a zig-zag pattern across the envelope surface.

[0034] The invention may be further modified within the scope of the appended claims.

Claims

1. Fan heater for temporary heating of a building site, including a fan (8), for transporting air through the fan heater (1) from an inlet (2) to an outlet (3), and at least one heating element (12) for heating the air passing through the fan heater (1), wherein the fan (8) is a cylindrical fan and each heating element (12) is arranged to envelop the cylindrical fan (8) at least partially, and the at least one heating element (12) is several heating elements arranged in the axial direction of the cylindrical fan (8) and in the heating elements (12) are approximately uniformly arranged across an outer envelope surface of the cylindrical fan (8) in the axial direction thereof, the several heating elements (12) being arranged so that they more or less circumscribe the cylindrical fan (8), characterized in that the heating elements (12) are U-shaped and arranged in several rows in the axial direction and in several layers in the radial direction, with the outermost heating elements (12) having a longer radius of curvature than the inner heating elements, and their radii of curvature are gradually less, with the innermost heating elements having the least radius of curvature, and wherein the innermost heating elements closely follow the curvature of at least half of the circumference of the cylindrical fan (8), and wherein all the heating elements (12) have their electrical connections at the bottom.

2. Fan heater according to claim 1 characterized in that the fan (8) expels air around its envelope surface.

3. Fan heater according to any of claims 1 to 2, characterized in that the fan (8) is arranged in an outer casing and that guiding plates (13) are arranged between the heating element (8) and the outer casing.

4. Fan heater according to claim 3, characterized in that the guiding plates (13) are arranged to direct the air towards an outlet (3) at the top of the fan heater (1), and the fan heater (1) has an inlet (2) for cool air on one of its sides.

5. Fan heater according to any of claims 1 to 3, characterized in that each heating element (12) extends along approximately half of the circumference of the cylindrical fan (8).

6. Fan heater according to claim 5, characterized in that each heating element (12) is arranged to follow the outer shape of the fan (8).

Ansprüche

1. Heizlüfter zum vorübergehenden Beheizen einer Baustelle, aufweisend einen Ventilator (8) zum Befördern von Luft durch den Heizlüfter (1) von einem Einlass (2) zu einem Auslass (3) und mindestens ein Heizelement (12) zum Beheizen der durch den Heizlüfter (1) strömenden Luft, wobei der Ventilator (8) ein zylindrischer Ventilator ist und jedes Heizelement (12) angeordnet ist, den zylindrischen Ventilator (8) zumindest teilweise zu umschließen, und das mindestens eine Heizelement (12) mehrere Heizelemente ist, die in der axialen Richtung des zylindrischen Ventilators (8) angeordnet sind, und die Heizelemente (12) in etwa einheitlich über eine äußere Hüllenfläche des zylindrischen Ventilators (8) in der axialen Richtung davon angeordnet sind, wobei die mehreren Heizelemente (12) derart angeordnet sind, dass sie den zylindrischen Ventilator (8) mehr oder weniger umgrenzen, dadurch gekennzeichnet, dass die Heizelemente (12) U-förmig und in mehreren Reihen in der axialen Richtung und in mehreren Ebenen in der radialen Richtung angeordnet sind, wobei die äußersten Heizelemente (12) einen längeren Krümmungsradius aufweisen als die inneren Heizelemente, und ihre Krümmungsradien allmählich abnehmen, wobei die innersten Heizelemente den kleinsten Krümmungsradius aufweisen, und wobei die innersten Heizelemente der Krümmung von mindestens einer Hälfte des Umfangs des zylindrischen Ventilators (8) genau folgen, und wobei alle Heizelemente (12) ihre elektrischen Anschlüsse auf der Unterseite haben.

2. Heizlüfter nach Anspruch 1, dadurch gekennzeichnet, dass der Ventilator (8) um seine Hüllenfläche Luft abgibt.

3. Heizlüfter nach einem der Ansprüche 1 bis 2, dadurch gekennzeichnet, dass der Ventilator (8) in einem äußeren Gehäuse angeordnet ist und dass Führungsplatten (13) zwischen dem Heizelement (8) und dem äußeren Gehäuse angeordnet sind.

4. Heizlüfter nach Anspruch 3, dadurch gekennzeichnet, dass die Führungsplatten (13) angeordnet sind, die Luft hin zu einem Auslass (3) an der Oberseite des Heizlüfters (1) zu leiten, und der Heizlüfter (1) einen Einlass (2) für Kühlluft an einer seiner Seiten aufweist.

5. Heizlüfter nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass sich jedes Heizelement (12) entlang in etwa einer Hälfte des Umfangs des zylindrischen Ventilators (8) erstreckt.

6. Heizlüfter nach Anspruch 5, dadurch gekennzeichnet, dass jedes Heizelement (12) angeordnet ist, der äußeren Form des Ventilators (8) zu folgen.

Revendications

1. Chauffage soufflant pour chauffer temporairement un chantier de construction, comprenant un ventilateur (8), pour transporter l'air à travers le chauffage soufflant (1) depuis une entrée (2) vers une sortie (3), et au moins un élément chauffant (12) pour chauffer l'air traversant le chauffage soufflant (1), le ventilateur (8) étant un ventilateur cylindrique et chaque élément chauffant (12) étant conçu pour envelopper au moins partiellement le ventilateur cylindrique (8), et l'au moins un élément chauffant (12) étant plusieurs éléments chauffants disposés dans la direction axiale du ventilateur cylindrique (8) et les éléments chauffants (12) étant disposés de manière approximativement uniforme sur une surface d'enveloppe externe du ventilateur cylindrique (8) dans sa direction axiale, les plusieurs éléments chauffants (12) étant disposés de sorte à circonscrire plus ou moins le ventilateur cylindrique (8), caractérisé en ce que les éléments chauffants (12) sont en forme de U et disposés en plusieurs rangées dans la direction axiale et en plusieurs couches dans la direction radiale, les éléments chauffants (12) les plus à l'extérieur ayant un rayon de courbure plus long que les éléments chauffants les plus à l'intérieur, et leurs rayons de courbure étant progressivement plus petits, les éléments chauffants les plus à l'intérieur ayant le rayon de courbure le plus petit, et les éléments chauffants les plus à l'intérieur suivant étroitement la courbure d'au moins la moitié de la circonférence du ventilateur cylindrique (8), et tous les éléments chauffants (12) ayant leurs connexions électriques dans la partie inférieure.

2. Chauffage soufflant selon la revendication 1, caractérisé en ce que le ventilateur (8) expulse de l'air autour de sa surface d'enveloppe.

3. Chauffage soufflant selon la revendication 1 ou 2, caractérisé en ce que le ventilateur (8) est disposé dans un boîtier extérieur et en ce que des plaques de guidage (13) sont disposées entre l'élément chauffant (8) et le boîtier extérieur.

4. Chauffage soufflant selon la revendication 3, caractérisé en ce que les plaques de guidage (13) sont conçues pour diriger l'air vers une sortie (3) au niveau de la partie supérieure du chauffage soufflant (1), et le chauffage soufflant (1) a une entrée (2) pour l'air frais sur un de ses côtés.

5. Chauffage soufflant selon l'une quelconque des revendications 1 à 3, caractérisé en ce que chaque élément chauffant (12) s'étend sur environ la moitié de la circonférence du ventilateur cylindrique (8).

6. Chauffage soufflant selon la revendication 5, caractérisé en ce que chaque élément chauffant (12) est conçu pour suivre la forme extérieure du ventilateur (8).

Drawing