FR3089880A1 - FLUID HEATING DEVICE FOR A MOTOR VEHICLE - Google Patents

Abstract

The invention relates to a device for heating a fluid (F) for a motor vehicle, comprising at least a first heating block (2) and a second heating block (3), each of the heating blocks (2 , 3) being disposed in an associated housing, a space between each heating block (2, 3) and an internal wall (12, 13) of the associated housing (5, 6) delimiting a fluid flow passage, each of heating blocks (2, 3) comprising a heating element provided with a thermal conductive coating.

Description

Description

Title of the invention: FLUID HEATING DEVICE FOR A MOTOR VEHICLE

The invention relates to a device for heating a fluid for a motor vehicle, of the type known as high electrical voltage.

In known manner, such a device comprises a heating block disposed in a housing, an external surface of the heating block being spaced from an internal wall of the housing so as to form a passage for the fluid, which is then heated in contact with the heating block.

The heating block is powered by an electrical voltage generally greater than 40V, which ensures efficient heating of the heat transfer fluid, itself preferably intended for a heating, ventilation and / or air conditioning system of a passenger compartment of a vehicle. automotive, or a thermal management system for a battery of an electric or hybrid vehicle.

However, such a known device has the drawback that the external surface of the heating block can reach temperatures above 200 ° C., which boils the layer of fluid in direct contact with the surface. The fluid which circulates in the device then comprises a liquid and gaseous mixture which can alter the operation of the associated heating system and which presents a risk of ignition of the gases, in particular of explosion, and of rise in pressure of the fluid.

The object of the invention is to remedy this drawback.

To this end, the invention relates to a device for heating a fluid for a motor vehicle, the device comprising at least a first heating block and a second heating block, each of the heating blocks being arranged. in an associated housing, called first housing and second housing, a space between each heating block and an internal wall of the associated housing delimiting a fluid flow passage, the first heating block comprising a fluid inlet in the device, the second heating block comprising a fluid outlet from the device, the device comprising a fluid communication channel between the first housing and the second housing, the device being configured so that the fluid flows from the inlet to the channel communication in a first main direction, in the communication channel in a third main direction, and from the communication channel to the exit in a d second main direction, the first and second directions of fluid flow being substantially orthogonal to the third direction of fluid flow, each of the heating blocks comprising a heating element provided with a thermally conductive coating.

Thanks to the coating, the external surface of the heating block is increased, which also increases the exchange surface between the fluid and the heating block. Then, the temperature of the fluid heated by the heating block is both reduced near and / or on the surface of the heating block and homogenized, thereby improving the operation of the associated system. In addition, the presence of a plurality of heating blocks in the heating device makes it possible to maximize the exchange surface between the coating and the fluid heated by the heating blocks. The presence of a plurality of heating blocks also allows continuity of operation of the device in the event of a failure of one of the heating blocks, and thus greater reliability of the device. A fluid heated by the device is for example water or a mixture of water and glycol or a refrigerant.

According to another characteristic of the invention, the inlet and the outlet are arranged opposite one another.

According to another characteristic of the invention, the device comprises a printed circuit board for controlling the heating blocks and means for connecting each heating block to said printed circuit board.

According to another characteristic of the invention, each passage between the heating block and the associated housing has a width of between 1mm and 2.5 mm.

According to another characteristic of the invention, each of the first and second heating blocks comprises a restriction part, in particular a cone-shaped restriction part, facing respectively the inlet and the outlet of the fluid. The restriction part makes it possible to limit the pressure drops on the fluid.

According to another characteristic of the invention, at least one temperature sensor is arranged in said restriction part. A heating block then makes it possible to position said at least one sensor as close as possible to the fluid inlet and / or outlet respectively. The shape of the restriction part is advantageously optimized to best position the temperature sensor.

According to another characteristic of the invention, the coating is an over-molding of metallic material or a ceramic layer.

According to another characteristic of the invention, each heating block comprises a heating element such as an armored resistor or a ceramic cartridge or a screen-printed track or one or more resistive elements with a positive temperature coefficient, called PTC elements.

According to another characteristic of the invention, each heating block includes reliefs on an external surface of the heating block.

The invention also relates to a heating, ventilation and / or air conditioning system for a motor vehicle, comprising a heating device as described above.

The invention also relates to a thermal management system of a battery for an electric motor vehicle, comprising a heating device as described above.

Brief description of the drawings

Other features, details and advantages of the invention will appear on reading the detailed description below, and on analysis of the accompanying drawings, in which: Fig.l

[Fig.l] illustrates a perspective view of a heating device according to the present invention, a housing being partially omitted;

Fig. 2

[Fig.2] illustrates a longitudinal sectional view of the device of Figure 1;

Fig. 3

[Fig.3] illustrates a longitudinal sectional view of a heating block of the device of Figure 1 according to a first embodiment;

Fig. 4

[Fig.4] illustrates a longitudinal sectional view of a heating block of the device of Figure 1 according to a second embodiment;

Fig. 5

[Fig.5] illustrates a longitudinal sectional view of a heating block of the device of Figure 1 according to a third embodiment.

Description of the embodiments

As illustrated in the figures, the invention relates to a heating device, referenced 1 in the figures. The device 1 heats a liquid fluid, such as water, denoted L in FIG. 2.

The device 1 is preferably associated with a heating, ventilation and / or air conditioning system of a passenger compartment of a motor vehicle and / or with a thermal management system of a battery for an electric or hybrid vehicle.

The device 1 is of the high voltage type ("high voltage" in English) that is to say that it is supplied with a voltage greater than 40V, for example 48V, or 60V up to 800-1000V.

The device 1 comprises at least a first and a second heating block. In the illustrated embodiments, the device comprises first and second heating blocks, referenced 2 and 3 respectively in the figures.

The heating blocks 2, 3, include a heating element and a coating of the heating element, as will be detailed later.

As can be seen from the figures, the device 1 also comprises a housing 4, in particular an envelope, provided with a first housing 5 associated with the first heating block 2 and a second housing 6 associated with the second heating block 3.

The first housing 5 comprises an inlet 7 for the fluid F in the device 1 while the second housing 6 comprises an outlet 8 for the fluid F outside the device 1.

As can be seen in the figures, the inlet 7 and the outlet 8 are arranged opposite one another. This arrangement ensures simple accessibility of the device 1 on the vehicle, since the fluid connections of the inlet and the outlet are accessible by the same face.

The first heating block 2 is disposed in the first housing 5, an external surface 9 of the first heating block 2 being spaced from an internal wall 10 of the first housing 5 by a distance dl, so as to define a passage 11 of fluid F in the first housing 5 around the first heating block 2.

Likewise, the second heating block 3 is disposed in the second housing 6, an external surface 12 of the second heating block 3 being spaced from an internal wall 13 of the second housing 6 by a distance d2, so to define a passage 14 of the fluid F in the second housing 6 around the second heating block 3.

The distances dl and d2 are preferably between 1mm and 2.5mm, which ensures good efficiency of the device 1. A distance greater than 2.5mm would result in zero fluid speed against the surface outside of the heating block, while a distance shorter than 1mm could lead to early fouling of the passage.

As shown in the figures, the first heating block 2 and the first housing 5 extend along a longitudinal direction LL

Likewise, the second heating block 3 and the second housing 6 extend along a longitudinal direction L2.

The longitudinal directions L1 and L2 are parallel to each other.

As also visible in the figures, the housing 4 comprises a communication channel 15 between the first housing 5 and the second housing 6.

The device 1 is configured so that the fluid F flows from the inlet 7 to the communication channel 15 in a first main direction PI, then in the communication channel in a third main direction P3, and from the communication channel to the exit in a second main direction P2.

As is clear from Figure 2, the main direction PI of fluid flow coincides with the longitudinal direction L1 while the main direction P2 of fluid flow coincides with the longitudinal direction L2.

The main direction P3 is orthogonal to the directions of fluid flow PI and P2, so that the circulation of the fluid in the device 1 describes a path of a general shape according to the letter U.

When the device 1 is operating, the fluid P enters the device 1 through the inlet 7 and then circulates in the passage 11 substantially in the direction PI, where it is heated by the first heating block 2. Then, the fluid P flows in the communication channel 15 in the direction P3 then in the passage 14, in the direction P2, where it is heated by the second heating block 3. Finally, the fluid P, heated, leaves the device 1 via exit 8.

Note that the use of two heating blocks ensures the heating of the fluid even in the event of failure of one of the blocks.

As also visible in the figures, each of the first and second housings 5, 6 comprises a bottom 16, 17, of planar shape, and opposite respectively to the inlet 7 and to the outlet 8. The first heating block 2 rests on the bottom 16 while the second heating block 3 rests on the bottom 17.

The device 1 comprises a printed circuit board 18 for controlling the heating blocks 2 and 3. Connection means 19, 20 of the heating blocks to the card are illustrated in FIG. 2.

As shown in Figure 2, the funds 16, 17 are placed on a housing 21 for protecting the printed circuit board 18.

Preferably, the heating blocks 2 and 3 are identical.

In the illustrated embodiments, the external surface 9, 12, of each of the heating blocks 2, 3, has a cylindrical shape from a flat bottom 22, 23 to a cone-shaped top part 24, 25.

A top 26 of the first heating block 2 faces a middle of the inlet 7 of the device 1 while a top 27 of the second heating block 3 faces a middle of the outlet 8 of the device 1.

The divergent cone shape from the inlet 7 (respectively the outlet 8) of the heating block 2 (respectively 3) makes it possible to reduce the resistance of the block to the flow of the fluid P and to limit the pressure losses.

Advantageously, each of the cones is provided with a temperature sensor 28, 29 in order to locally obtain a temperature of the fluid entering and leaving the device 1. These measurements make it possible to control the power of the heating elements and detect any overheating that may occur in the heating elements.

As already indicated, each heating block comprises a coating of a thermally conductive material, such as ceramic or aluminum.

According to the variant illustrated in Figure 3, the illustrated heating block 2 is an armored resistor 30 topped with aluminum 31.

According to the variant illustrated in Figure 4.1e heating block 2 is a cartridge 32 with ceramic coating 33.

According to the variant illustrated in Figure 5.1e heating block 2 is a coil resistor 34, in particular a resistive coil, topped with aluminum 35.

The coating makes it possible to avoid the first direct contact between the heating element and the first fluid, and to increase the external surface 9, 12 of the heating block, which increases the exchange surface between your blocks. and the fluid, and thereby lowers the average temperature of the fluid on the surface of the heater blocks. Thus, your risk of the fluid boiling is greatly reduced.

It should be noted that the 1st heating block is either full or hollow as shown in FIGS. 3, 4 and 5, which makes it possible to reduce the mass of the device 1.

On illustrated embodiments, the outer surface 9, 12 is smooth. However, the invention is not limited to this configuration. Reliefs can be added, such as pins and / or grooves, in order to further increase the exchange surface between the fluid L and your heating blocks and to create turbulence. This increases the performance of the heat exchange between the 1st heater block and the fluid to be heated.

Claims (1)

Claims [Claim 1] Fluid heating device (F) for a motor vehicle, the heating device (1) comprising at least a first heating block (2) and a second heating block (3), each of the heating blocks (2 , 3) being arranged in an associated housing, called first housing (5) and second housing (6), a space between each heating block (2, 3) and an internal wall (12, 13) of the associated housing (5, 6) delimiting a fluid flow passage (11, 14), the first heating block (2) comprising an inlet (7) of fluid in the device (1), the second heating block (3) comprising an outlet (8) of fluid outside the device (1), the device (1) comprising a fluid communication channel (15) between the first housing (5) and the second housing (6), the device (1) being configured to that the fluid (F) flows from the inlet (7) to the communication channel (15) in a first main direction (PI), in the communication channel (15) along a t third main direction (P3), and from the communication channel (15) to the outlet (8) in a second main direction (P2), the first and second directions of fluid flow (Pl, P2) being substantially orthogonal to the third direction of fluid flow (P3), each of the heating blocks (2, 3) comprising a heating element (30, 32, 34) provided with a thermal conductive coating (31, 33, 35 ). [Claim 2] Device according to claim 1, in which the inlet (7) and the outlet (8) are arranged opposite one another. [Claim 3] Device according to one of the preceding claims, comprising a printed circuit board (18) for controlling the heating blocks (2, 3) and connection means (19, 20) of each heating block (2, 3) to said printed circuit board (18). [Claim 4] Device according to one of the preceding claims, in which each of the first and second heating blocks (2, 3) comprises a restriction part, in particular a cone-shaped restriction part facing respectively the inlet (7) and at the fluid outlet (8). [Claim 5] Device according to the preceding claim, comprising at least one temperature sensor (28, 29) disposed in said restriction part. [Claim 6] Device according to one of the preceding claims, in which the coating is an overmolding of metallic material or a ceramic layer. [Claim 7] Device according to one of the preceding claims, in which each heating block (2, 3) comprises a heating element such as an armored resistor or a ceramic cartridge or a screen-printed track or one or more resistive elements with a positive temperature coefficient, so-called PTC elements. [Claim 8] Device according to one of the preceding claims, in which each heating block (2, 3) comprises reliefs on an external surface of the heating block (2, 3). [Claim 9] Heating, ventilation and / or air conditioning system for a motor vehicle, comprising a heating device according to one of the preceding claims. [Claim 10] A thermal management system for a battery for an electric motor vehicle, comprising a heating device according to one of claims 1 to 8. 1/5