DRY HEATER WITH UNIFORMLY DISTRIBUTED THERMAL ENERGY

Abstract

 An electric radiator comprising: at least one profile made of aluminium or alloys thereof, shaped in an elongated form; said at least one profile having a hollow central part delimited by a surface; an electric resistance positioned in said hollow central part; characterized in that said at least one profile is an extruded profile; said electric resistance is an insulated electric resistance having a surface load ranging from 0.6 to 1 W/cm2; the interspace which is created between the resistance and said hollow central part has a width ranging from 0.1 to 0.33 mm, more preferably from 0.1 to 0.15 mm.

Description

[0001] The present invention refers to an electric radiator, in particular a dry heater with uniformly distributed thermal energy.

[0002] The search for greater thermal comfort and dimensional versatility than that obtained with electric convectors or radiators and the desire to obtain energy savings through a radiating surface suited to the room size are driving the development of various types of fluid and dry electric radiators.

[0003] Normally the radiators are composed of heating bodies designed to operate with water and converted to electric operation by fitting in the radiator cavities one or more electric resistances that transmit their thermal energy to the surface either via a fluid or via solid structures that fill the space between the resistances and the heat transmission surfaces.

[0004] If these cavities do not have a constant geometry, the resistances must be purposely produced to mirror the inner shape of the radiating element.

[0005] Furthermore, heating bodies designed for the passage of water or manufactured in plants that produce water radiators (in the case of aluminium radiators produced mainly by die-casting or extrusion) do not allow production flexibility in terms of either height or width.

[0006] The possibility of producing heating bodies with extruded elements fitted with resistances with heating cable or inserted and fixed electric resistances is also known.

[0007] These techniques can limit diffusion of the heat produced by the resistance, thus preventing optimization and reducing performance of the resulting system, or can cause high noise levels due to the significant thermal differences between the various components which are interlocked and not able to adapt to different thermal expansions.

[0008] The object of the present invention is to provide an electric radiator that overcomes the drawbacks of the known art.

[0009] A further object is to provide an electric radiator that offers dimensional flexibility during production.

[0010] A further object is to provide an electric radiator which is simple to produce.

[0011] A further object is to provide an electric radiator with non-fixed elements able to freely expand, guaranteeing heat transmission without causing noise.

[0012] A further object is to be able to replace the heating elements with extreme simplicity.

[0013] In accordance with the present invention, said objects and others still are achieved by an electric radiator comprising: at least one profile made of aluminium or alloys thereof in an elongated shape; said at least one profile having a hollow central part delimited by a surface; an electric resistance positioned in said hollow central part; characterized in that said at least one profile is an extruded profile; said electric resistance is an insulated electric resistance having a surface load ranging from 0.6 to 1 W/cm2; the interspace that is created between the resistance and said hollow central part has a width ranging from 0.1 to 0.33 mm, more preferably from 0.1 to 0.15 mm.

[0014] Further characteristics of the invention are described in the dependent claims.

[0015] This solution has various advantages compared to the solutions of the known art.

[0016] The peculiarity of this invention consists in the fact that the radiator uses extruded aluminium profiles with shapes suited to the desired dimensions and powers. The extruded profile is therefore one single piece comprising a hole appropriately calibrated to guarantee the coupling tolerances of the present invention. This allows several heights to be obtained with the same profile and the same resistance in a rapid inexpensive manner (cutting the profile to the desired height) and also several widths, thanks to the modularity, adapting to the available spaces and desired powers.

[0017] The advantage therefore consists in the fact that it is possible to rapidly insert the resistances in the cavity of the extruded profile after completion of the radiator consisting of profiles cut to the desired length in order to obtain a wide range of heights with the same very limited investment typical of extrusion dies.

[0018] The resistance, which by its very nature is perfectly cylindrical, is produced to be inserted in the circular cavity uniform throughout the length of the profile without any terminal part having diameter greater than the mean diameter throughout the length of the resistance in order to slide freely within the profile, ideally being able to pass from end to end of the length thereof without any interference.

[0019] Furthermore, in the circular cavity where the resistance is inserted, no material is inserted and the resistance is sized so that there is clearance for it to be inserted in the circular cavity of the radiator and slide freely inside said cavity.

[0020] The particular insulation of the resistance and the absence of interference or installation locking elements avoid the noise typical of radiators of the known art which have resistances integral with the containment structure.

[0021] The fact that the resistance has a specific power lower than that of the known art means that it does not require close contact with the radiator material, thus avoiding the creation of hot points.

[0022] The small air gap that is created between the resistance and the radiator hole where it is inserted guarantees uniform heating.

[0023] The characteristics and advantages of the present invention will be evident from the following detailed description of a practical embodiment thereof, illustrated by way of non-limiting example in the attached drawings, in which:

figure 1 shows schematically a pair of profiles joined to each other, seen in section from above, in accordance with a first embodiment example of the present invention;

figure 2 shows schematically a profile, seen in perspective, in accordance with a first embodiment example of the present invention;

figure 3 shows schematically a profile, seen from the side and in section, in accordance with a first embodiment example of the present invention;

figure 4 shows schematically a plug of a profile, in accordance with a first embodiment example of the present invention;

figure 5 shows schematically a profile, seen in section from above, in accordance with a second embodiment example of the present invention;

figure 6 shows schematically a profile, seen in perspective, in accordance with a second embodiment example of the present invention;

figure 7 shows schematically a profile joining system, in accordance with a second embodiment example of the present invention;

figure 8 shows schematically a profile, seen in section from above, in accordance with a third embodiment example of the present invention;

figure 9 shows schematically a profile, seen in perspective, in accordance with a variation of a third embodiment example of the present invention;

figure 10 shows schematically a profile joining system, in accordance with a third embodiment example of the present invention;

figure 11 shows schematically a pair of profiles joined to each other, seen in section from above, in accordance with a fourth embodiment example of the present invention;

figure 12 shows schematically a pair of profiles joined to each other, seen in perspective, in accordance with a fourth embodiment example of the present invention;

figure 13 shows schematically a profile joining system, in accordance with a fourth embodiment example of the present invention;

figure 14 shows schematically a resistance, seen laterally, in accordance with the present invention.

[0024] Referring to the attached figures, a radiator, in accordance with the present invention, comprises a plurality of profiles joined to one another, of which those shown in the figures and described here are an example.

[0025] The profiles are joined to one another by means of threaded joining bars having appropriate length which, via suitable holes on the faces between the elements and spacers, allow the elements to be joined to form the radiator, or by means of appropriately shaped angle bars fixed to the rear face of the element via fixing systems including screws or rivets.

[0026] The profiles all have a circular hole throughout the length of the profile, vertical channels of various shapes to increase the convective motion and fins of various shapes and dimensions.

[0027] A cylindrical electric resistance is inserted inside the circular hole.

[0028] One characteristic of the present invention is that there is no interference between the resistance and the hole and that the resistance is able to slide freely in the profile within the upper limit formed by the cable outlet and the lower limit formed by either a screw or a rivet or a deformation of the profile or equivalent systems.

[0029] The fins and the vertical channels of the profiles and connection diaphragms with the front surface allow control of the high temperatures generated by the electric resistance and are able to partly dissipate the temperature generated and ensure, on the front face, an appropriate temperature for comfort.

[0030] The profiles are made of extruded aluminium with constant section, therefore in one single piece, allowing the production of radiators with different powers by varying the length of the profile and the number of profiles coupled.

[0031] In a first embodiment of an electric radiator, said radiator is formed of an extruded profile 10 which in this case is formed of a first vertical channel 11 with rectangular section. The first vertical channel 11 can have connection bridges between its rear wall and its front wall, in this case not present. At the rear and centrally to it there is a second vertical channel 12 with circular section from which some fins 13 branch off. At the rear and laterally to the first vertical channel 11 are spacers 14 which delimit the rear overall dimension. Any other fins 15 are positioned between the second vertical channel 12 and the spacers 14.

[0032] The profile 10 is also provided with a circular hole 20 positioned on the lateral walls of the first vertical channel 11, and an eyelet 21 also positioned on the lateral walls of the first vertical channel 11.

[0033] The second vertical channel 12 has, at one end, a hole 22 which establishes communication between the second vertical channel 12 and the first vertical channel 11.

[0034] For the union between the various profiles 10, a threaded bar 25 is used which is made to pass through the holes 20 of the various profiles. Between one profile and another, a spacer 26 is positioned, fixed by nuts 27.

[0035] A resistance 30 is positioned in the second vertical channel 12. The resistance 30 has the shape of a cylindrical tube terminating in two wires 31. Between the resistance 30 and the hole 12 there is no interference and therefore the resistance is able to slide freely in the profile within the upper limit formed by the cable outlet 22 and lower limit formed by a stop 84.

[0036] The wires 31 are made to pass inside the hole 22, also acting as upper limit to sliding of the resistance, and the connections between the various resistances of the radiator are inside the first vertical channel 11; the electric connections, between the various profiles 10, are made to pass inside the eyelets 21.

[0037] A plug 35 is positioned, preferably interlocked, at the upper end of the first vertical channel 11 to ensure containment and user safety with respect to the electric connections present inside. The plug 35 has a surface lower than that of the section of the first vertical channel 11 to leave space for the convective motion.

[0038] In a second embodiment of an electric radiator, said radiator is formed of an extruded profile 40 which is very similar to that of the first embodiment.

[0039] It comprises a third vertical channel 41 with rectangular section, with connection bridges 42 between its rear wall and its front wall, and a fourth vertical channel 43 with circular section from which some fins 44 branch off. At the rear and laterally to the third vertical channel 41 are the spacers 45, and any other fins 46 are positioned between the fourth vertical channel and the spacers.

[0040] The fourth vertical channel 43 comprises an eyelet 49 and the third vertical channel 41 has further connection holes 52 at the rear.

[0041] The profile 40 differs from the profile 10 mainly due to the connection system of the profiles and management of the electric connections.

[0042] The various profiles 40 are joined by means of C-section connection angle bars 50, which contain the connection cables and are fixed to the profile 40 by means of brackets 51 with screws tightened in the holes 52. The angle bars 50 must be positioned at a height such as to cover the holes 47.

[0043] The cables 31 run out of the holes 47 and the connections are made inside the angle bars 50.

[0044] In a third embodiment of an electric radiator, said radiator is formed of an extruded profile 60 which comprises a fifth vertical channel 61 with oval section, with connection bridges 62 between its rear wall and its front wall, and a sixth vertical channel 63 with circular section from which some fins 64 branch off.

[0045] The sixth vertical channel 63 comprises a hole 65 and the fifth vertical channel 61 has at the rear an eyelet 66 and other connection holes 67.

[0046] In a variation of the third embodiment, alternatively to the sixth vertical external channel 63 with the fins 64, a channel 94 is provided with relative fins, inside the channel 61.

[0047] The various profiles 60 are joined by means of connection angle bars 68 having C-shaped section, which contain the connection cables and are fixed to the profile 40 by means of holes 69 arranged in the area of the holes 67. The angle bars 67 have grooves for the passage of the resistance cables 31, and the connections are made inside the angle bars 68.

[0048] In a fourth embodiment of an electric radiator, said radiator is formed of an intermediate extruded profile 70 and a terminal extruded profile 71.

[0049] The profile 70 comprises a front wall 72 and a rear wall 73. At the back of the rear wall 73 is a seventh vertical circular channel 74 for positioning the resistance 30. Between the seventh vertical channel 74 and the front wall 72 is an eighth vertical channel 75 with triangular/trapezoidal section.

[0050] On the rear wall 73 is an eyelet 76 for passage of the resistance cables 31 and other connection holes 77.

[0051] The terminal extruded profile 71 differs from the intermediate extruded profile 70 in that it has a lateral closing wall 78 and an eyelet 79 on the rear wall 73 providing a grommet for passage of the cables into the profile.

[0052] The various profiles 70 are joined by means of connection angle bars 80 with C-shaped section, which contain the connection cables and are fixed to the profile 70 by means of holes 81 arranged in the area of the holes 77. The angle bars 80 have holes 82 and 83 in the area of the holes 76 and 79.

[0053] The electric resistance 30 has a diameter slightly smaller than the diameter of the holes 12, 43, 63, 74, so that the resistance 30 can be easily inserted in the holes.

[0054] The holes 12, 43, 63, 74 are through holes and can be closed after insertion of the resistance 30 by means of plugs or other.

[0055] The resistance 30 is produced in the required lengths and powers and with the necessary diameter, so that it can adapt perfectly to the length of the radiating element.

[0056] Furthermore, in order to guarantee an electric insulation suited to requirements, the resistance 30 is made with one single insulation or a double electric insulation; in this way the radiator can be adapted to the various market requirements by varying the resistance only.

[0057] The resistance comprises the power supply cables 31 which, according to requirements, can have single or double insulation compatible with the design temperatures (typically ranging from 80 to 200°C) which carry the electric power supply to the resistance 30.

[0058] The cables 31 are sealed with respect to the structure of the resistance 30 by means of bicomponent silicone rubber, also providing a centring function; internally one or more resistance wire spirals are kept centred by means of structures that can be made for example of ceramic, magnesium oxide etc. contained inside a tube which can also be made of AISI 304 stainless steel with external diameter of 14 mm.

[0059] To obtain a further insulation, the resistance with single insulation is inserted inside a tube which can be made of AISI 304 and have a diameter of 18 mm.

[0060] In one embodiment, the resistance 30 has a diameter of 16 mm with negative tolerance and the holes 12, 43, 63, 74 have a diameter of 16.2 mm with positive tolerance. Preferably, the difference between the diameter of the resistance 30 and the diameter of the holes 12, 43, 63, 74 is comprised between 0.2 and 0.65 mm, more preferably between 0.2 and 0.3 mm, and even more preferably 0.2 mm. Therefore, the air gap which is created between the resistance and the holes has a width comprised between 0.1 and 0.33 mm, more preferably between 0.1 and 0.15 mm, and even more preferably 0.1 mm.

[0061] The resistance 30 is inserted by sliding into the holes 12, 43, 63, 74 and its axial movement is left free between the upper limit formed by the cable outlet 22 and the lower limit formed by a stop 84.

[0062] In this way the resistance cannot move beyond the stroke ends but is allowed a certain amount of movement in order to minimize the noise caused by the different expansion coefficients between resistance and profile and facilitate the installation thereof.

[0063] In an alternative embodiment the holes 12, 43, 63, 74 could have another section, for example square.

[0064] The resistance 30 has a length substantially equal (insofar as allowed) to that of the profiles so as to guarantee the containment thereof and distribution of the heat over the majority of the length of the profile. By way of example, the length of the resistance can be 5-20% shorter than the length of the profile.

[0065] Both the length and the diameter can provide a resistance surface able to guarantee a low surface load which, for example, can be 0.6-1 W/cm2, thus obtaining a low specific power.

[0066] In particular, a resistance 1000 mm long with diameter of 16 mm and surface load of 1 W/cm2 has a power of 500W. The same power on a length of 1500 mm has a surface load of 0.66 W/cm2.

[0067] In this way it is possible to optimize the thermal efficiency of the system.

[0068] The length of the cables 31 coming out of the resistances 30 is such as to allow the external connections to the elements.

[0069] The electric connections between resistances 30 are made either inside the confined spaces of the profiles or inside the connection angle bars provided with appropriate protective closure.

[0070] The connection between the various cables is made by means of systems which can also be rapid installation systems such as compression clamps that allow the various components to be electrically connected in one single compression operation.

[0071] In the case of double insulation radiators equipped with double insulation resistances as described above, once the clamps have been assembled, they are covered by a sheath which provides electrical insulation.

[0072] The sheath can also be of heat-shrink type or silicone type with fibreglass core.

[0073] Within the spaces of the profiles or within the connection angle bars, adequately protected by closure, thermostats, thermal fuses or anything else necessary for safe operation of the radiators can be installed in series with the electric connection.

[0074] The radiator thus conceived is subject to numerous modifications and variations, all falling within the scope of the inventive concept; furthermore, all the details can be replaced by technically equivalent elements.

Claims

1. An electric radiator comprising: at least one profile made of aluminium or alloys thereof, shaped in an elongated form; said at least one profile having a hollow central part delimited by a surface; an electric resistance positioned in said hollow central part; characterized in that said at least one profile is an extruded profile; said electric resistance is an insulated electric resistance having a surface load ranging from 0.6 to 1 W/cm2; the interspace which is created between the resistance and said hollow central part has a width ranging from 0.1 to 0.33 mm, more preferably from 0.1 to 0.15 mm.

2. The radiator according to one of the preceding claims characterized in that said hollow central part has a circular section throughout its length.

3. The radiator according to one of the preceding claims characterized in that said resistance has a cylindrical shape.

4. The radiator according to claims 2 and 3 characterized in that the difference between the diameter of the resistance (30) and the diameter of the holes (12, 43, 63, 74) is comprised between 0.2 and 0.65 mm, preferably comprised between 0.2 and 0.3 mm.

5. The radiator according to one of the preceding claims characterized in that no material or fluid is interposed between said electric resistance and said surface.

6. The radiator according to one of the preceding claims characterized in that said electric resistance consists of a resistance wire surrounded by an insulating layer.

7. The radiator according to one of the preceding claims characterized in that said electric resistance consists of a resistance wire surrounded by two insulating layers.

Drawing