Thermal block for heating liquids

Abstract

A thermal block (100) for heating a liquid, comprises: a tube (200) for the passage of liquid, provided with an inlet (3) and an outlet (4) and with at least one segment (200) with corrugated walls (6), a massive block (1) co-molded outside said pipe (200) so that the inlet (3) and the outlet (4) are outside the massive block (1), one resistive element (5) for heating the massive block (1).

Claims

1. A thermal block for heating water in a home appliance, comprising: a tube for the passage of said water, provided with a wall, an inlet and an outlet, a massive block consisting of a mass of heat-conducting material, at least one resistive element for heating said massive block, wherein the tube is arranged in the thermal block so that the wall thereof is immersed in and separate from said mass, and so that said inlet and outlet are outside the massive block, wherein the massive block is molded outside the tube, wherein the massive block is made of aluminum, wherein the tube is made of stainless steel, and wherein the tube has at least one corrugated segment with inner surface irregularities, whereby the heat exchange between the massive block and the water is increased, wherein said thermal block has parallelepiped dimensions with two end bases which are greater in size than the other dimensions of the parallelepiped, and wherein the tube comprises a meander serpentine, the path of which is mainly developed on two superimposed planes placed close to a respective end base of said two end bases.

2. The thermal block according to claim 1, wherein each inner surface irregularity of said inner surface irregularities extends over the whole perimeter of the orthogonal section of the tube or over at least one portion of said perimeter.

3. The thermal block according to claim 1, wherein said tube consists of a meander serpentine.

4. The thermal block according to claim 1, wherein the tube is corrugated over the whole length thereof.

5. The thermal block according to claim 1, wherein said thermal block and said tube have mainly cylindrical dimensions.

6. The thermal block according to claim 1, wherein said resistive element comprises a corrugated sheath so as to optimize the heat exchange between said massive block and said resistive element.

7. The thermal block according to claim 1, wherein the home appliance is a coffee maker.

8. A process for manufacturing a thermal block having the features set forth in claim 1, wherein there are provided a tube having at least one corrugated segment with inner surface irregularities, at least one resistive element, a mass of heat-conducting material, heating means adapted to melt said mass of heat-conducting material, injection means and a mold, said process comprising the steps of: arranging the tube inside the mold, arranging the at least one resistive element in the mold, melting the mass of heat-conducting material via the heating means so as to obtain a molten mass, injecting the molten mass into the mold via the injection means, so that the molten mass surrounds the tube and the at least one resistive element, cooling the molten mass to ambient temperature.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further features and advantages of the present invention will be more apparent in the light of the detailed description of preferred, but not exclusive, embodiments of a thermal block for heating liquids according to the present invention, shown by the way of non-limitative example, with the aid of the accompanying drawings, in which:

(2) FIG. 1 shows an axonometric view of a first embodiment of a thermal block according to the present invention;

(3) FIG. 2 shows an axonometric view of a component which can be used in the thermal block in FIG. 1;

(4) FIG. 2a shows a longitudinal section of a portion of the component in FIG. 1;

(5) FIG. 2b shows a longitudinal section of a portion of a component which can be used in a thermal block according to a variant of the invention;

(6) FIG. 3 shows an axonometric view of a component according to a variant of the first embodiment;

(7) FIG. 4 shows an axonometric view of a second embodiment of a thermal block according to the present invention;

(8) FIG. 5 shows an axonometric view of a component which can be used in the thermal block in FIG. 4;

(9) FIG. 5a shows a variant of the component in FIG. 5.

(10) The same reference numerals refer to the same components or to components having the same functional and/or structural features.

DETAILED DESCRIPTION OF THE INVENTION

(11) With reference to figures from 1 to 3, according to a first embodiment, a thermal block for heating a liquid, in particular water, in a home appliance is indicated as a whole by reference numeral 100.

(12) The thermal block is generally shaped as a parallelepiped. The thermal block 100 comprises a tube 200 for the passage of water to be heated. Tube 200 is provided with an inlet 3 for the water at low temperature to be heated and an outlet 4 for the heated water. Being crossed by water for human consumption, the tube 200 is made of stainless steel. The thermal block 100 comprises a massive block 1 co-molded outside tube 200, so that the inlet 3 and the outlet 4 of tube 200 are outside the massive block 1. The massive block 1 consists of a mass of material capable of ensuring high thermal capacity, so as to accumulate the thermal energy which must be transmitted to the water, and with high thermal conductivity so as to transfer the thermal energy accumulated in the massive block 1 to the water circulating in tube 200. The material for manufacturing the massive block 1 is aluminum also because this material is particularly adapted to be molded. However, any other material with similar features can be used for the purposes of the present invention for manufacturing the massive block and the tube. Since the thermal capacity also depends on mass, the massive block is also conveniently dimensioned to ensure the required thermal capacity.

(13) Any molding technique can be used, such as die-casting, low-pressure shell molding, earth/sand casting, loss-wax casting or other.

(14) The thermal block 100 comprises a resistive element 5 for heating the massive block 1 due to the passage of current. The resistive element 5 is also joined to the massive block 1 by co-molding and is provided with two ends 5a, 5b protruding with respect to massive block 1. The resistive element 5 comprises a lining sheath 7. According to a variant of the present invention (not shown), such a lining is corrugated so as to increase the heat exchange surface per length unit, thus improving the heat exchange between the resistive element 5 and the massive block 1.

(15) Tube 200 is folded on itself and comprises a portion having a plurality of straight segments and a plurality of curved segments. In other words, the tube comprises a meander serpentine, the path of which is developed on two superimposed planes. More in detail, tube 200 comprises a first meander portion 200a including inlet 3 and a second meander portion 200b including outlet 4 and arranged in series with respect to said first portion 200a. The straight segments 6 are corrugated with inward protrusions. In particular, each protrusion is circular and extends over the whole perimeter of the section orthogonal to the tube, i.e. the section orthogonal to the flowing direction of the liquid. Irregularities of the outer surface of the tube correspond to the inner protrusions. By virtue of the inner protrusions, a turbulence is generated in the liquid flow, so as to cause a remixing of the liquid itself and thus increase the heat exchange between the massive block 1 and tube 200 and between the latter and the water which flows therein. The curved segments instead are substantially smooth, as well as the two segments of tube close to inlet 3 and outlet 4. FIG. 2b shows a variant of corrugation of the tube according to the invention, in which segment 15 has a part 16 in which each protrusion is substantially shaped as a circumferential arc, extending over a portion of the perimeter of the orthogonal section of the tube, i.e. the section orthogonal to the flowing direction of the liquid, while another part 17 of segment 15 is smooth.

(16) The massive block 1 is substantially shaped as a parallelepiped with two opposite and parallel end bases 11, 12, upper and lower ends respectively, more extended than the other faces of the parallelepiped. The two meander portions 200a, 200b lay on two respective superimposed planes placed close to the lower base 12 and close to the upper base 11 of the massive block 1, respectively, and an inclined transition portion is present therebetween. Inlet 3 and outlet 4 are placed, with respect to the massive block 1, at two respective faces which are mutually opposite and substantially orthogonal to the bases. Such a pattern of tube 200 makes a considerable development in length possible in addition to supplying a heating chamber with the desired volume capacity and high heat exchange surface.

(17) According to a variant of the first embodiment, shown in FIG. 3, alternatively to that shown in FIG. 2, tube 201 is of the meander type, lying on a single plane also comprising inlet 3 and outlet 4, in which a single rectlinear segment 8 has smooth walls, while the other straight segments 6 have a corrugated surface. Also in this case, the two segments of tube close to inlet 3 and outlet 4 have smooth walls.

(18) With reference to FIGS. 4 and 5, in the second embodiment, a thermal block for heating a liquid, in particular water, in a home appliance is shown as a whole by reference numeral 101 and has the same features as the thermal block 100 of the first embodiment except for those described below.

(19) The massive block 1 is substantially cylindrical in shape with two circular bases 13, 14, upper and lower bases, respectively. A portion of tube 202 is folded on itself according to a cylindrical spiral with inlet 3 and outlet 4 placed at opposite ends of the spiral.

(20) Tube 202 is completely corrugated with inner protrusions except for two portions close to inlet 3 and outlet 4. Each protrusion extends over a portion of the perimeter of the section orthogonal to the longitudinal axis of the tube, i.e. in orthogonal direction with respect to the flowing direction of the liquid. According to a variant of the second embodiment, shown in FIG. 5a, tube 203 is completely corrugated with surface irregularities over the whole perimeter of the tube section orthogonal to the flowing direction of the fluid. When tube 203 is inserted into the massive block, the inlet 3 and outlet 4 are outside the massive block. According to a further variant of the second embodiment (not shown), a spiral segment is provided with mutually alternating corrugated segments and smooth segments, so as to conveniently modulate the thermal power exchanged as a function of the specific application.

(21) The invention thus achieved the object illustrated above while obtaining a plurality of advantages. In particular, the surface corrugation of the tube with respect to the traditional smooth pipe solution allows to: increase the turbulence of the fluid within the pipe itself and thus increase the convective heat exchange coefficient as well; shorten the length of the pipe, thus simplifying its shape and decreasing the overall sizes and thus the cost of the thermal block due to the increase of the heat exchange power per length unit; accept a higher amount of lime scaleper length unit of the tubedue to the presence of inner pockets caused by the corrugation; reduce the deposit of lime scale due to the turbulence increase inside the pipe.