Heating device for use thereof in a vehicle

Abstract

A heating device for heating fluids, such as water or a liquid coolant, for application in electric or hybrid vehicles, where the absence of an internal combustion engine or its shorter time of use requires using heating devices for heating either the passenger compartment or other parts of the vehicle that require it. The heating device is provided with a configuration which limits the temperature to the temperature at which heat exchange occurs between the heat generation source and the liquid to be heated, such that the liquid does not generate precipitates, prolonging the service life of the device.

Claims

1. A heating device for use thereof in a vehicle and configured for heating a thermal fluid, the heating device comprising: a chassis comprising a separating plate; an inlet port for the entry of the thermal fluid; an outlet port for the exit of the thermal fluid wherein the inlet port is in fluid communication with the outlet port through a chamber for the thermal fluid; and at least one heating plate fixed to the chassis comprising on a first side a heat generation region, and a second side, opposite the first side, wherein the heating plate has an essentially rectangular configuration with the inlet port and the outlet port in correspondence with one of the smaller sides of the rectangle, wherein the chamber for the thermal fluid is defined between the separating plate and the second side of the heating plate, wherein the heat generation region comprises at least one electric resistor, wherein the heating device further comprises three dissipating elements, with these dissipating elements being on the second side of the heating plate and positioned in correspondence and in thermal communication with at least one part of the heat generation region, wherein the three dissipating elements are made of aluminum, wherein each of the three dissipating elements is intended for being located on a portion of the second side of the heating plate, wherein each of the three dissipating elements comprises fins distributed according to a main direction, wherein the three dissipating elements are a first, a second, and a third dissipating element, wherein an attachment between the three dissipating elements and the heating plate is by means of brazing, and wherein the three dissipating elements determine a family of routes according to a broken straight path from the inlet port to the outlet port, wherein the broken straight path has a “U” shape, such that: the first and the third dissipating element extend along a direction established by a larger side of the rectangle, and the ends of the first and third dissipating elements located on the opposite side where the inlet port and the outlet port are located have a chamfered termination, leaving a free area occupied by the second dissipating element having an essentially triangular configuration.

2. The heating device according to claim 1, wherein the heat generation region comprises a sub-region formed by a plurality of electric resistors configured as a plurality of longitudinal bands distributed parallel and interconnected to one another either in series or in parallel, and wherein the sub-region is subdivided into a plurality of resistor sub-regions.

3. The heating device according to claim 2, wherein each resistor sub-region has an independent power supply.

4. The heating device according to claim 1, wherein the three dissipating elements with fins are configured by means of at least one corrugated folded sheet attached to the heating plate.

5. The heating device according to claim 1, wherein the heating plate comprises: a substrate configured as a flat plate, wherein on the first side where the heat generation region is located, the heating device comprises at least one layer of dielectric material, located on the substrate; one or more electric resistors arranged on the layer of dielectric material; and a protective layer located on the one or more electric resistors.

6. The heating device according to claim 1, wherein the substrate of the heating plate is made of stainless steel.

7. The heating device according to claim 1, wherein the second dissipating element extends along a transverse direction with respect to the direction of the first and the third dissipating elements.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other features and advantages of the invention will become more apparent from the following detailed description of a preferred embodiment given only by way of non-limiting illustrative example in reference to the attached drawings.

(2) FIG. 1 shows an exploded perspective view of an embodiment in which the set of elements forming the heating device is shown.

(3) FIG. 2 shows a perspective view of one of the sides of the heating plate, the side on which the heat dissipating elements are located.

(4) FIG. 3 shows a perspective view of the opposite side of the heating plate with respect to what is shown in FIG. 2, the side showing the set of resistors for heat generation.

(5) FIGS. 4A-4B: FIG. 4A shows a side front view of the heating device according to the preceding embodiments of the invention in which there is identified a cross-section B-B according to a broken plane, such that the lower part of the plane of section shown in this figure is oblique. FIG. 4B shows section B-B identified in FIG. 4A where the heating plate is cross-sectioned, and the lower part, due to the oblique plane of section, allows observing a perspective view of the resistors and their connectors.

(6) FIG. 5 shows a perspective view of a schematic depiction of a portion of the heating plate according to one embodiment.

(7) FIG. 6 shows a section view of a schematic depiction of an embodiment of the heating plate where the heating plate is shown opposite to how it is shown in the preceding figure.

(8) FIG. 7 schematically shows a portion of the chamber with a cross-section of a dissipating element formed by fins and where the most relevant parameters which in this case allow defining the hydraulic diameter of the channels formed by said fins are identified.

DETAILED DESCRIPTION

(9) FIG. 1 shows an exploded perspective view of an embodiment of the heating device (1) wherein the main body is formed by a chassis (1.1) which, in this embodiment, is formed by molded aluminum. The chassis (1.1) is a structural body comprising an inlet port (I) for the entry of the thermal fluid and an outlet port (O) for the exit of the thermal fluid. In this example, both the inlet port (I) and the outlet port (O) are prolonged into a connection spigot. The configuration of the chassis (1.1) is that of a perimetral wall with a separating plate (1.1.1) which gives rise to two spaces, one space on each side of the separating plate (1.1.1).

(10) Above this separating plate (1.1.1) a first space forms a housing for a circuit board (1.5) intended for managing the power supply.

(11) Both the heat generation sources and the elements facilitating heat transfer from the heat generation sources to the thermal fluid are located on the other side of the separating plate (1.1.1), under same following the orientation shown in FIG. 1.

(12) The housing for the circuit board (1.5) is closed with a lid identified in this description as upper lid (1.6).

(13) The heating device (1) comprises a chamber (C) for the thermal fluid which is in communication with the inlet port (I) and with the outlet port (O). According to the invention, the separating plate (1.1.1) of the chassis (1.1) forms one of the walls of the chamber (C) for the thermal fluid, giving rise to a very compact design of the device.

(14) In the same FIG. 1, shown below the chassis (1.1) there is a sealing gasket which is housed in a perimetral groove which is not shown in this perspective view. The chamber (C) has a very small height compared to the area formed by the internal wall formed by the separating plate (1.1.1).

(15) In this embodiment, the walls (1.1.2) are an integral part of the chassis (1.1) configured, for example, during the injection of the main body of the chassis; nevertheless, it is possible to configure the walls (1.1.2) by means of a frame, in an independent part, later attached by means of brazing.

(16) The internal wall of the chamber (C) opposite the wall formed by the separating plate (1.1.1) is formed by a heating plate (1.2), the plate which is responsible for generating and transmitting heat to the thermal fluid.

(17) The heating plate (1.2) shown in the perspective view of FIG. 1 shows a smooth surface formed by the substrate (1.2.1) of the plate (1.2) and above same, also according to the orientation of FIG. 1, a block formed by a set of dissipating elements (1.3).

(18) In this embodiment, the block formed by the set of dissipating elements (1.3) is attached by brazing to the substrate (1.2.1) of the heating plate (1).

(19) This side of the heating plate (1.2) where the dissipating elements (1.3) are located is the side identified as side B.

(20) The opposite side of the heating plate (1.2), the side identified as side A, is the side containing the heat generation elements.

(21) In this embodiment, the heat generation elements are tracks made of resistive material which generate heat by the passage of current. These tracks made of resistive material intended for generating heat by the passage of current will be referred to hereinafter as resistors (1.2.2). According to another embodiment, the heat generation elements are Peltier plates which transfer heat to the substrate (1.2.1) of the heating plate (1.2).

(22) Finally, as shown in the lower part of FIG. 1, the device is closed by a lid referred to as lower lid (1.4).

(23) The separating plate (1.1.1) does not completely close the passage between the space forming the housing of the circuit board (1.5) and the space where the heating plate (1.2) is located, but rather there are openings (1.1.3) which are traversed by connectors (1.7) communicating the heating plate (1.2) with the circuit board (1.5) intended for electrically supplying the heating plate (1.2).

(24) FIG. 2 shows a perspective view of the heating plate (1.2) on the side where the dissipating elements (1.3) are located, side B, and FIG. 3 shows the opposite side of the same heating plate (1.2), side A, with a region (R) formed by electric resistors (1.2.2) for heat generation.

(25) According to this embodiment, the electric resistors (1.2.2) are configured in the form of flat tracks forming bands which are distributed parallel, forming sub-groups where each sub-group is supplied independently. The entire resistor sub-groups cover the resistor region (R), with this region (R) being the heat generation region and a region subjected to high temperatures.

(26) The heat generated by the electric resistors (1.2.2) is transferred to the other side of the plate through the substrate (1.2.1) of the heating plate (1.2) until reaching the surface of the opposite side.

(27) According to an example that does not belong to the invention, it has been verified that if the side of the heating plate (1.2) which is oriented towards the inside of the chamber (C) is left free, without dissipating elements (1.3), the elevated temperature of the plate corresponding to the position of the electric resistors (1.2.2) degrades the thermal fluid, giving rise to deposits which build up in the same elevated temperature sites. Over time, the solid deposits establish a thermal barrier which prevents dissipating the heat generated by the electric resistors (1.2.2) towards the thermal fluid. The heat that is not dissipated causes the temperature to increase further until reaching an excessive temperature, burning the electric resistors (1.2.2).

(28) Any protuberance in a solid deposit formation environment favors the precipitation of more solids. Nevertheless, contrary to what is expected, in this embodiment dissipating elements (1.3) in the form of projections configured as fins emerging from the surface of the heating plate (1.2) have been included, and as a result, it has been verified that contrary to what is expected the heating device (1) can operate under nominal conditions for long periods of time without solid deposits being formed.

(29) By carrying out experiments with embodiments of the invention where the temperature of the resistors has been raised above the nominal temperature, even reaching extreme values to cause precipitates, it has been verified that the device still operates correctly since heat exchange is maintained through the dissipating elements (1.3) even though the base has many deposits.

(30) In one embodiment, as is also shown in FIG. 4B, the height of the dissipating elements (1.3) is such that it reaches the opposite surface formed by the separating plate (1.1.1) save a tolerance that is sufficient so as not to make the contact or a contact with forces that may generate fatigue in the materials, due to the effect of expansion.

(31) The embodiment shown in FIGS. 1 to 4B comprises a plurality of dissipating elements (1.3) wherein: each of the dissipating elements (1.3) is intended for being located on a limited area of the second side (B) of the heating plate (1.2); each dissipating element (1.3) is configured according to a longitudinal direction; and wherein the set of dissipating elements (1.3) determine a family of routes according to a broken straight path from the inlet port (I) to the outlet port (O).

(32) In this embodiment, the dissipating elements (1.3) are configured according to a longitudinal direction given that they comprise a plurality of fins (1.3.1) having a straight configuration and distributed parallel to one another.

(33) According to another embodiment, the dissipating elements (1.3) are formed by fins with a wave form extending according to a sinusoidal path. The direction along which the sinusoid extends is the direction identified as longitudinal direction.

(34) In view of FIG. 2, the heating plate (1.2) comprises three dissipating elements (1.3) in turn formed by a plate from which there emerge fins (1.3.1) oriented in a given longitudinal direction. According to this embodiment, the heating plate (1.2) has an essentially rectangular configuration with the inlet port (I) and the outlet port (O) in correspondence with one of the smaller sides of the rectangle.

(35) The first dissipating element (1.3) covers approximately half of the rectangular area extending along the direction established by the larger side of the rectangle. The third dissipating element (1.3) covers approximately the other half of the rectangular area also extending along the direction established by the larger side of the rectangle. The ends of the first and third dissipating elements (1.3) located on the opposite side where the inlet port (I) and the outlet port (O) are located have a chamfered termination, leaving a free area occupied by the second dissipating element (1.3) having an essentially triangular configuration.

(36) The channels formed between the dissipating fins (1.3.1) form a family of routes according to a broken straight path in three segments, a longitudinal segment extending from the inlet port to the opposite end along the first dissipating element (1.3), a second transverse line along the second dissipating element (1.3), and a final longitudinal line along the third dissipating element (1.3) extending to the outlet port (O), the three lines configuring a “U”. According to another embodiment, the heating plate (1.2) comprises a single block with the three dissipating elements (1.3) giving rise to continuously extending fins for configuring the “U”, for example, by means of stamping in a single part.

(37) Each of the plates with fins (1.3.1) forming each of the dissipating elements is attached by brazing to the substrate (1.2.1) of the heating plate (1.2).

(38) According to another embodiment, as indicated above, one or more dissipating elements (1.3) is formed by a corrugated sheet also attached by brazing to the substrate (1.2.1) of the heating plate (1.2).

(39) FIG. 2 also shows the connectors (1.7) which place the connection terminals (1.2.5) of the electric resistors shown in FIG. 3 in electric communication with respective supply terminals located on the circuit board (1.5) which allows managing the current passing through each of the resistors (1.2.2) from the circuit board, whereas the circuit board (1.5) is separated from the space where the heat is being generated.

(40) FIG. 3 shows heat generation sub-regions formed by groups of resistive tracks distributed in parallel. There are shown on the larger sides of the heat generation region (R) tracks running parallel to the edge for directly supplying each of the groups of resistors directly from an independent terminal. This independence allows separately managing the supply of each of the sub-regions for example if the heat requirements are different in areas of the heating plate (1.2) which are also different.

(41) FIG. 4A shows a side front view of the device which mainly shows the side walls of the chassis (1.1), the upper lid (1.6), the inlet of the thermal fluid to be heated, and the sockets (1.8) for the supply and control of the device, which sockets (1.8) are in communication with the circuit board (1.5), as is also shown in FIG. 1.

(42) FIG. 4A shows the broken line B-B which defines a transverse plane of section which is oblique in its lower part for generating a perspective view of the resistors of the heating plate (1.2).

(43) FIG. 4B shows a section view of the device according to the plane of section B-B shown in FIG. 4A. This section shows the separating plate (1.1.1) which it leaves in the upper part the circuit board (1.5), which is shown in this embodiment with supports separating it from the separating plate (1.1.1) on which it is fixed.

(44) Following the orientation used in FIG. 4B, below the separating plate (1.1.1) there is configured the chamber (C), limited by an upper internal wall and the side walls (1.1.2) integrally formed with the separating plate (1.1.1), and in the lower part, limited by the heating plate (1.2) which is fixed in this embodiment by means of screws (1.2.6). This same section shows a sealing gasket (1.9) assuring the leak-tight closure between the heating plate (1.2) and the chassis (1.1) for configuring the chamber (C).

(45) The inside of the chamber (C) shows the plurality of dissipating elements (1.3) formed by a plate attached by brazing to the heating plate (1.2) and the fins (1.3.1) emerging towards the separating plate (1.1.1), covering the entire height of the chamber (C) and filling in all the available space.

(46) The oblique view of section B-B allows having visual access to the set of resistors extending along the heat generation region (R) in correspondence with the dissipating elements (1.3) located on the other side of the heating plate (1.2).

(47) The resistors (1.2.2) are supplied from the connection terminals (1.2.5) for the supply of the heating plate (1.2), with these connection terminals (1.2.5) being connected to the circuit board (1.5) through the connectors (1.7).

(48) FIG. 5 shows a perspective view of a schematic detail of a portion of the heating plate (1.2) with a first lower side A with a heating region (R) identified by a discontinuous line covered by the resistors (1.2.2) which generate the heat which is transferred through the heating plate (1.2) to the second side B, the side shown in the upper part in this figure.

(49) In the upper part, the second side B is where the dissipating element (1.3) is welded, which element in this schematic example is shown in the form of a corrugated sheet which gives rise to fins (1.3.1) connected in twos through a flat surface in the form of a ridge.

(50) FIG. 6 shows a section of the same heating plate (1.2), now shown with the first side A upwards and the second side B downwards. The dissipating element (1.3) is now oriented downwards and attached by brazing to the substrate (1.2.1). Above the substrate (1.2.1), according to one embodiment, there is a dielectric layer (1.2.3) on which the resistors (1.2.2) are arranged and with a protective layer (1.2.4) covering the entire dielectric layer (1.2.3) and the resistors (1.2.2).

(51) That is, the structure of the heating plate (1.2) according to this embodiment comprises: a substrate (1.2.1) configured as a flat plate wherein on the first side (A) where the heat generation region (R) is located, it comprises at least one layer (1.2.3) of dielectric material, located on the substrate (1.2.1), one or more electric resistors (1.2.2) arranged on the layer (1.2.3) of dielectric material; and a protective layer (1.2.4) located on the one or more electric resistors (1.2.2).

(52) According to another embodiment, the heating plate (1.2) also comprises connection terminals, not shown in the figure, for the power supply of the electric resistor or resistors (1.2.2).

(53) Several experiments have been carried out and based on same, a set of configurations has been found in which there is a high degree of safety where, without resulting in a high pressure drop caused by the dissipating elements (1.3) and the channels that they form, conditions which prevent the formation of solid deposits due to the generation of precipitates are generated.

(54) It has been verified that said configurations are those in which the hydraulic diameter ϕ.sub.h of the channels formed by the protrusions or projections of the dissipating elements (1.3), the hydraulic diameter defined as the variable ϕ.sub.h=4A/p, with A being the transverse area of the channel and p the perimeter of said channel, are in the range of [1.5-5].

(55) Out of these configurations, a subset of configurations has been found in which, even though the thermal fluid boils, the temperature is kept below the limit at which the liquid generates precipitates. These configurations have a hydraulic diameter ϕ.sub.h in the range of [1.5-4].

(56) An even more specific subset of configurations has been found, where the pressure drop is especially low and where the amount of precipitates is considerably lower. Said set verifies that the hydraulic diameter ϕ.sub.h of the channels formed between the protrusions or projections is in the range of [2-4].

(57) The experiments performed indicate that these results are independent of the liquid coolant used as thermal fluid and are also independent of the material of the protrusions.

(58) FIG. 7 shows a specific case where the dissipating elements are fins having an essentially rectangular section emerging from a base plate and showing a small separation from the opposite surface. FIG. 7 depicts in its lower part the surface corresponding to the heating plate (1.2) and in its upper part the inner wall of the chamber (C) formed by the separating plate (1.1.1) of the chassis (1.1) which gives rise to the opposite inner wall of the chamber (C).

(59) Located on the surface of the heating plate (1.2) is the base plate of the dissipating element (1.3) and on the latter, the fins. FIG. 7 depicts the most relevant parameters of this configuration which allow establishing the hydraulic diameter as the following amount:

(60) ${\varnothing }_h=\frac{4\left[\left(H_C-t_b\right)d+t_f\left(H_C-H_f-t_b\right)\right]}{2\left[\left(H_C-t_b\right)+\left(d+t_f\right)\right]}$

(61) where

(62) H.sub.c is the separation height between internal surfaces of the chamber (C);

(63) H.sub.f is the height of the fin emerging from the base of the dissipating element (1.3);

(64) t.sub.b is the thickness of the base;

(65) d is the separation between facing surfaces between two consecutive fins; and,

(66) t.sub.f is the thickness of the fin.

(67) In other specific cases, it is necessary to refer to the general definition of hydraulic diameter.

(68) All the features described in this description (including the claims, description and drawings) can be combined in any combination, with the exception of combinations of such mutually exclusive features.