Technical Field

The present invention relates to a liquid-filled electric radiator having an upper distribution duct and a lower collection duct. The two ducts is in liquid communication with each other through on one hand a number of connecting ducts within the radiator body and on the other hand through a separate vessel connected to the radiator. The vessel is connected to the distribution and collection ducts at two diagonally opposing positions on the radiator and houses an electric immersion heating element for heating the liquid. The heating element is arranged in the part of the vessel going along the collecting duct. State of the- Art Liquid-filled electric radiators are coming more and more into use. The liquid in such radiators is usually transformer oil, which has, suitable properties for the purpose. The immersion heater used for heating the oil is arranged within the space in the radiator which is used for the oil flow, usually a collection duct situated downwards in the radiator. In such a case the heater is inserted in the collection duct from one short end of the radiator. The insertion opening then being closed by a liquid-sealing stub through which the electric supply lines to the heater ass out to the in¬ side of a casing for electric components. The casing is thus arranged as an extension of the lower end portion of the radiator. E.g. such a known radiator is described in French Patent No. 1 586 411. Such known liquid-filled electric radiators have a disadvantage in that the liquid is heated by the immersion heater, at the lowest point of the radiator to obtain circulation by convection. The heat-emitting

plates of the radiator will thus be warmer downwards than they are upwards, which has an unfavourable effect on the air intended to be heated by the radiator, since the air in the room where the radiator is placed. normally circulates from the floor and up to the ceil¬ ing- The known liquid-filled electric radiators, which emit more heat downwards near the floor than at their upper portion situated closer to the ceiling thus have poor efficiency. The cold air stream in the room first meets the highest temperature of the radiator and takes up heat, while the heat exchange further up along the radiator surface will be poor, since the air has already become well-heated at its previous contact with the lower portion of the radiator. A further disadvantage in the known liquid-filled electric radiators is that due to the greater heat in the downward portions, where the casing for the electric components is also situated, the casing has a high interior temperature. Measurements have shown that in a liquid-filled electric radiator with a surface temperature of 80 C the temperature inside the casing is approximately 40 C. This makes the casing unsuitable, if not impossible, as a location for mounting the radiator thermostat. To solve these disadvantage mentioned above it has been proposed to arrange the electric immersion heat¬ ing element in a separate vessel. Liquid-filled radiators of this type are known from e.g. French Patent No.922393. The radiators are of casted grill type having the separate vessel arranged under the radiator body. The vessel is connected to the end of the collection duct via a longer return tube and to the end of the distribution duct via a separate ascending tube for the liquid heated in the vessel. An inconvenient drawback of the radiator known from the French patent is the demand for a thermostat controlling the energy supply from the electric heating

element in dependence of the temperature of the return liquid. Another drawback is that the vessel as well as the tubes are arranged outside the boarder lines of the radiator body. Also electric radiators of panel type are previously known, e.g. from Norwegian Patent No. 61 522 and 59 936, where a vessel body having a circular cross section is arranged in a vertical position between two plane-parallel panel radiator bodies. The vertical vessel is connected to the collection and distribution ducts through transverse branch pipes and contains a concentric tube housing an electric heating element. Thus, there is only an indirect liquid heating which gives the radiator a poor efficiency. Contributing to the poor efficiency is also that no optimum self circulation of the liquid is obtained by a vertical heat¬ ing element. Disclosure of Invention

It is an object of the present invention to provide a liquid-filled electric radiator of the type mentioned above but having improved performance with respect to construction as well as to function. This is obtained through a radiator of panel type having the distribution, collection and connecting ducts shaped in a known manner between two press shaped and welded heat- emitting plates in combination with a separate vessel being in form of an angularly bent pipe -having mainly a uniform cross section area and forming two limbs of which one, the lower limb, is arranged parallel to and in level with the collection duct and at its free end it is connected to the collection duct via a short branch pipe while the other limb of the bent pipe is arranged to accompanying one short side of the radiator within the boarder line of the radiator body to have the free end thereof connected to the distribution duct, whereby the electric immersion heating element housed

in the lower limb has electric supply means arranged at the free end of the limb having a stub which liquid- tight terminates the pipe and through which pass electric lines for current supply to the element, said lines continuing to a casing for electrical components. By having a vessel designed as an angularly bent pipe with a simple pipe joint to the distribution duct as well as to the collection duct of the radiator a housing for the electric immersion heating element being well apt to the radiator area is obtained. The heater housing will then be well protected by the radiator body. The bent pipe as such is easy to assemble as well as the heating elemented introduced therein. The heating element is introduced in and separated from the bent pipe together with the stub. The uniform cross section area assists in obtaining optimum liquid flow through the radiator.

A further ^* advantage of the liquid-filled radiator according to the invention is that due to the low temperature of the radiator at the branch pipe connect¬ ing the collection duct to the lower limb of the bent ^' pipe the casing for electric components can be arranged in close connection to the branch pipe and accommodate a thejrmostat for detection of the air temperature, Th _* ³ thermostat detector in such a case is protected from direct heat radiation from the radiator by a wall protruding from the casing. Operation of the liquid- filled electric radiator in accordance with the invention has shown that the inside temperature of the casing is approximately 20° c for amaximum surface temperature (80° C) at the radiator. Preferred embodiment

The invention will now be described in detail in connection with the preferred embodiment summarily described above, and which is illustrated on the accompanying drawings, where

5 Figure 1 is a front elevation of the liquid- filled electric radiator in accordance with the invention,

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Figure 2 is the same radiator seen from the 5 rear

Figure 3 is a section along the line III - III in Figure 2 and

Figure 4 illustrates, partially in section, the lower part of the radiator at the connection end 10 of the electric heating element, with the casing for electrical components removed.

As will be seen from Figure 1 , the preferred embodiment of the liquid-filled electric radiator in accordance with the invention has a front surface 1 , 15 the appearance of which agrees with that of a conventional water radiator, apart from a casing 10 with associated thermostat 11 or other heat-detecting ^• regulating means, e.g. in the form of a semi-conductor. The front surface 1 , as well as the rear surface 2 of the 20 radiator (Figure 2), has an upper distribution duct 3 connected to a cwnward-collection duct4 v±»'connecting ducts 15 (Figure 4).

The thermostat 11 is arranged on the front side of the casing 10 at a distance from the radiator body. The casing 10 has a wall 14 to protect the thermostat 11 25 from direct heat radiation from the radiator.

A pipe 5 comprising two limbs 6, 7 is, shown in Figure 2 on the rear side 2 of the radiator. One limb 6 is disposed parallel to, and at the same height as, the collection duct 4 and is coupled to the latter at its 30 free end, which is terminated in the casing 10. The limb 7 is disposed parallel to the remote end wall of the radiator, as seen from the casing 10, and has its free end connected to the distribution duct 3. The pipe 5 is thus coupled to the internal liquid flow system 35 of the radiator at diagonally opposed points on the radiator.

Figure 4 is a longitudinal cross-section of the pipe limb 6. It will be seen from the figure that the pipe 5 is in liquid-conducting communication with the radiator collection duct 4 via the branch pipe 8. The branch pipe 8 is arranged in .the immediate vicinity of the pipe end, which is closed off liquid-tight by a stub 9. An electric immersion heating element 12 is inserted in the limb 6 of the pipe 5, the electrical supply lines of the element passing through, the stub 9 out to the connection means 13. The connection means 13 are electrically connected to the electrical components (not shown in Figure 4) disposed in the casing 10.

The limb 6 of the pipe 5 is also advantageously utilized for suspending the radiator on a wall fasten¬ ing. The wall fastening can thus be mounted for turning on the limb 6.

In operation, the radiator is filled with iquid, preferably transformer oil. The element 12 is supplied with current in response to the setting on the thermostat 11. On being supplied with current the element 12 heats the liquid in the limb 6 of the pipe 5. The heated liquid rises up through the other limb 7 and into the radiator distribution duct 3. The hot liquid is then propagated in the radiator, as is usual with a radiator included in a central heating installation, and down to the collection duct 4. From the collection duct 4 the liquid then migrates once again to the limb 6 via the branch pipe 8. Effective convection is thus obtained in the radiator, which has its highest temperature upwards at the input in the distribution duct 3. One of the cooler regions on the radiator is around the branch pipe 8, where the casing 10 for the thermostat 11 is also arranged. Although the embodiment of the -liquid-filled electric radiator in accordance with the invention

described above and in connection with the drawings is the one preferred, the invention can be modified in different ways without departing from its principle. The present invention may thus not be regarded as restricted to the described and illustrated embodiment, and the scope thereof is determined entirely by the following claims.