MOTOR VEHICLE COMPRISING A COOLING SYSTEM EQUIPPED WITH A HEAT EXCHANGER CONNECTED TO A TURBINE COUPLED TO A CURRENT GENERATOR, AND METHOD BASED ON SUCH A VEHICLE

Abstract

The invention relates to a motor vehicle comprising a heat source (S) and a cooling system for cooling the heat source (S), the cooling system comprising:- a radiator (R);- at least one circulation pump (P);- at least one heat exchanger (HE);- at least one turbine (T) connected to a generator (G);- at least one first cooling circuit (C1) comprising a first fluid, connecting the radiator (R) to said pump (P), then to said heat exchanger (HE), then to said turbine (T); and- at least one second cooling circuit (C2) comprising a second fluid, connecting said heat exchanger (HE) to the source (S). The invention also relates to a method based on such a vehicle. Figure 2

Description

Title of the invention: MOTOR VEHICLE COMPRISING A COOLING SYSTEM EQUIPPED WITH A HEAT EXCHANGER CONNECTED TO A TURBINE COUPLED TO A CURRENT GENERATOR, AND METHOD BASED ON SUCH A VEHICLE

[0001] The invention relates to the field of engine and / or battery cooling systems, and frontal impact absorption systems for motor vehicles.

[0002] In the prior art, cooling systems are a largely standardized solution illustrated in [Fig.l]. They comprise a flat type exchanger (radiator R and condenser C) comprising a large number of fins of a defined width, contained longitudinally for space reasons, and compacted as much as possible laterally and vertically to increase the heat exchange surface.

[0003] The working fluid is water or a refrigerant fluid called “coolant”.

[0004] The radiator R is cooled by air A, in an open loop with a fan V which forces the air to achieve a forced air flow.

[0005] Furthermore, in the prior art, the shock absorber is structural and of the passive type. It may comprise a structure with fixed geometry, made of metal (or composite), in series solutions, largely standardized; or a structure with variable geometry, made of metal, specific, without series application.

[0006] The cooling systems of the prior art are thermally efficient, having a large exchange surface, fans to force the air and a cooling circuit which is developed for conventional working fluids (water, coolants).

[0007] They imply a strong architectural and style impact: the system needs to be in front of the vehicle with an air intake which penalizes the architectural performance, the performance in terms of repairability and high-speed shock.

[0008] They are very ineffective from a shock point of view: in the event of a shock, they constitute a rather rigid volume which penalizes the efficiency of the length of the front block, as well as the ratio between the space dedicated to energy absorption and the total length of the front block.

[0009] As structural shock absorbers, their passive structure implies bulk, their metallic constitution implies significant weight, while a composite constitution implies low operational robustness because energy absorption occurs through rupture of the material.

[0010] Document DE102017009453 proposes a cooling system comprising a honeycomb structure with longitudinally oriented parallel channels. The honeycomb structure of the motor vehicle is provided, in particular, with a latent heat accumulator in the form of a coating of a phase-change material. This coating provides a passive cooling system.

[0011] An objective of the present invention is to remedy the defects of the prior art, and in particular to propose a cooling and shock absorption solution where the cooling is active to be more effective than in the prior art, and where the shock absorption is substantially effective.

[0012] To achieve this objective, the invention provides a motor vehicle in a spatial reference frame comprising a longitudinal axis along a direction of movement of the motor vehicle; a lateral axis perpendicular to the longitudinal axis, and a vertical axis perpendicular to the longitudinal axis and to the lateral axis, the motor vehicle comprising a heat source and a cooling system for cooling the heat source, the cooling system comprising: - a radiator; - at least one circulation pump; - at least one heat exchanger; - at least one turbine connected to a generator; - at least a first cooling circuit comprising a first fluid, connecting the radiator to said pump, then to said heat exchanger, then to said turbine; and - at least one second cooling circuit comprising a second fluid, connecting said heat exchanger to the source.

[0013] Advantageously, the invention provides an active cooling system, based on a closed working cycle, with a working fluid which is preferably ammonia or bioethanol. The cooling circuit is more efficient and produces electricity. The heat exchanger maximizes heat exchanges, which makes it possible to reduce the mass and size of the exchanger.

[0014] According to one variant, the generator is connected to a battery.

[0015] This makes it possible to store the energy generated by the first cooling circuit.

[0016] According to one variant, the battery is a traction battery.

[0017] This makes it possible to increase the autonomy of a traction battery vehicle.

[0018] According to one variant, the radiator has a honeycomb or parallel tube structure with orifices arranged longitudinally along the longitudinal axis.

[0019] This makes it possible to reinforce the rigidity of the radiator so that it can absorb frontal impacts.

[0020] According to one variant, the heat exchanger has a honeycomb or parallel tube structure with orifices arranged longitudinally along the longitudinal axis.

[0021] This makes it possible to reinforce the rigidity of the heat exchanger so that it can absorb frontal impacts.

[0022] According to one variant, the first fluid comprises ammonia or bioethanol.

[0023] Ammonia helps improve cooling efficiency. Bioethanol allows the use of an ecological fluid.

[0024] According to a variant, the second fluid comprises a coolant.

[0025] This allows the use of a standard fluid.

[0026] According to one variant, the motor vehicle comprises: - two first cooling circuits each connecting said radiator to a respective pump, then to a respective heat exchanger, then to a respective turbine; - two second cooling circuits each connecting said respective heat exchanger to the source.

[0027] This makes it possible to cool, at several points, one or more heat sources.

[0028] According to one variant, the heat source comprises an internal combustion engine and / or an electric machine.

[0029] This makes it possible to cool a heat engine or an electric machine.

[0030] The invention further relates to a method for cooling a heat source of a motor vehicle according to the invention, comprising the following steps: - setting up at least a first cooling circuit comprising a first fluid, connecting the radiator to said pump, then to said heat exchanger, then to said turbine; and at least a second cooling circuit comprising a second fluid, connecting said heat exchanger to the source; and - operate said pump so as to cool the heat source.

[0031] The invention will be further detailed by the description of non-limiting embodiments, and on the basis of the appended figures illustrating variants of the invention, in which: - [Fig.l] schematically illustrates a cooling system according to the prior art; - [Fig.2] schematically illustrates a cooling system according to a first embodiment of the invention; - [Fig.3] schematically illustrates a cooling system according to a second embodiment; and - [Fig.4] schematically illustrates a honeycomb structure of a heat exchanger or radiator.

[0032] The present invention presents a high performance cooling system which is compact and allows to restructure the space in the front block of the vehicle, giving a lot of freedom, while acting as structural elements to prevent and protect the vehicle from frontal impacts.

[0033] The invention applies to cooling an internal combustion engine, an electric machine or a storage system, such as for example a battery pack.

[0034] The invention proposes an active cooling system, based on a closed working cycle, with a working fluid which is for example ammonia or bioethanol.

[0035] A cooling circuit with one or two cooling loops is proposed. It is more efficient and produces electricity, unlike the heat exchange circuit shown in [Fig.l].

[0036] The heat exchanger can be of the flat type, or of the tube type with a working fluid with an increased calorific coefficient, in order to maximize heat exchanges and thus reduce the mass and size of this exchanger.

[0037] The working fluid with increased calorific coefficient is suitable to be ammonia or bioethanol.

[0038] The cooling circuit also produces electricity, following the expansion of the working fluid in a turbine T, the shaft of which is connected to a current generator G. The generator G produces electricity which is subsequently stored in the high-voltage battery B of the vehicle.

[0039] One or two exchangers (figures 2 and 3), with honeycomb structures or tubes are arranged lengthwise on the Y axis and can be either parallel to the vehicle stretchers or replace them.

[0040] The radiator R is part of the cooling system where the surface area necessary for the heat exchange is obtained with a series of large slats in X and stacked but without being compacted in Z, on the contrary they have a laterally undulating shape in such a way as to form a honeycomb type system (or a laterally sinusoidal system); the geometry thus obtained makes it possible to maintain the same thermal efficiency and to become efficient also in frontal impact.

[0041] The invention makes it possible to solve the following problems of the prior art: - the standard cooling system is open loop, has a fan, does not produce electricity and contains a stack of radiator, exchanger and a fan. The system of the invention improves the thermodynamic cooling efficiency, by making the system active (controllable by electricity), compact: the size of the exchangers is reduced, and producing electricity thanks to a generator G placed at the end of the shaft of a turbine T which rotates following the expansion of ammonia, the working fluid, in the cooling circuit; - moreover, the standard cooling system is not efficient in shock; the invention further proposes to make the HE heat exchanger shock efficient.

[0042] The inventors have removed the fan V of the prior art, reduced the size of the radiator R, in particular by putting the exchanger HE, by adding: - a closed-loop working circuit, consisting of an electric pump P, the HE exchanger, composed of honeycomb-type lamellae or tubes; - the expansion turbine T; - generator G connected to turbine T, which produces current when the working fluid (ammonia) expands; and - storage of electricity in a high-voltage battery B.

[0043] The working fluid is ammonia.

[0044] The inventors have further modified the system of slats (in the case of a flat type exchanger) to provide a larger longitudinal size (in X); a vertical geometry (in Z) that is undulating instead of flat; and a reduced number of slats in the vertical (in Z).

[0045] A variant illustrated in [Fig.3] comprises two cooling working circuits in parallel, with the same working fluid, as well as symmetrical loops, composed of two turbines T, two pumps P, two exchangers HE, and two generators G producing electric current. The exchanger (radiator R) is common, and is located in the middle of the front block of the motor vehicle.

[0046] In this case, the HE exchangers can replace the stretchers of the front block of the vehicle, and also fulfill the function of impact protection, at the same time as the cooling function.

[0047] Concerning the details of the invention, the cooling fluid of the converter (hot source S such as an internal combustion engine and / or an electric machine) or of the energy store (the battery B) circulates in a first cooling circuit C1, which passes through a first heat exchanger HE. The heat exchanger HE is arranged in the Y axis of the front block and can also have a structural function (replacing the stretcher for example).

[0048] The HE exchanger can be made of either honeycomb or tubes. It is crossed by two fluids - the fluid which cools the converter (source S) / stores energy, and the working fluid which is in the second working cycle - preferably ammonia. Inside the HE exchanger, a heat exchange therefore takes place between the (hot) cooling fluid of the converter and the (cold) ammonia.

[0049] The external ammonia working circuit has a dual function: to take the heat from the hot source S and to produce electricity, that is to say to convert the heat dissipated in the ammonia into work to produce electricity.

[0050] Once the ammonia is heated in contact with the walls of the HE exchanger by the fluid from the hot source S, the ammonia changes phase, thanks to these thermal properties modynamics, and becomes in supercritical phase and in vapor. Therefore, it has a high temperature and pressure. The ammonia in this supercritical state makes its expansion (pressure drop) by passing through a turbine T. The pressure drop and the flow of the fluid make the turbine T turn, thus a mechanical work is produced at the exit of the turbine shaft T. To convert this mechanical work and use it in a useful form, we propose to connect to the same rotating shaft an electric generator G, which by turning produces electricity. This electricity can then be stored in another battery B, or to be sent back to the network (if we have a high voltage rechargeable battery to cool).

[0051] Once the ammonia has passed through the turbine T, it loses pressure and temperature. In order to return it to its liquid state and condense it, a radiator R, acting as a condenser, is passed through. The ammonia is thus condensed at ambient air temperature. The exchange in the radiator R is between the ammonia and the air.

[0052] The structure of the radiator R can be a honeycomb or tubes.

[0053] The radiator R no longer needs to be positioned at a strong or forced airflow by a fan, so the R radiator can be moved and space in front of the front end of the vehicle can be freed up. This gives more freedom in the architecture and style of the vehicle.

[0054] Once the ammonia has returned to the liquid phase, it is pumped by an electric pump P, in a loop towards the heat exchanger HE to reproduce mechanical work in the turbine T, and therefore electricity.

[0055] A variant of the system can be imagined. It is presented in [Fig.3]. The inventors plan to make two cooling and working cycles, symmetrical on each side, and the HE heat exchangers can have the functions of exchangers, but also of constituting the two stretchers of the vehicle.

[0056] HE heat exchangers can be made of honeycomb or tubes.

[0057] The radiator R (heat exchanger or condenser) can be placed at the front of the vehicle, but also on the side or at the rear, if it is necessary to free up space for other components, within the front block.

[0058] The cooling system may be integrated for structural functions in structures in the center of the front block, or on the lateral sides of the front block.

[0059] In the case of integration into the stretchers (lateral sides of the front block), the system is efficient in thermal and shock thanks to the internal definition of a tubular structure, having a conventional three-dimensional geometry (of the tubular network type) or optimized according to the characteristics of the TPMS type (for "triply periodic minimal surface" in English) with undulations in the direction of the flow in the pipes.

[0060] In the case of integration into a structure centered in the front block, the system of cooling object has a honeycomb-like geometry, as illustrated in [Fig.4].

[0061] In the case of realization by a honeycomb structure, each corrugated layer is in reality a conduit for circulating the refrigerant fluid.

[0062] The choice of fluid can also be optimized in order to optimize the surface area required for the thermal function.

[0063] The depth Tl, where Tl is in the X direction of the vehicle, can be of the order of 200 - 500 mm; this will be the result of the compromise between: - thermal requirement: depending on the temperature, the type of fluid and the surface; - impact resistance requirement: in relation to the level of energy to be absorbed; - depending on the volume available in the front block; for this, favorable architectures are: vehicles with a long front block, or engines at the rear or integrated into the wheels or in any case a small engine in the rear part of the front block.

[0064] This type of geometry is also effective in shock, by crushing the cells longitudinally; maintaining a quasi-constant force until the assembly is completely compacted; absorbing energy linked to the constant force on the crushing stroke.

[0065] The level of effort is adjustable according to the size of the cells (according to Tl) and the thicknesses. This type of structure is characteristic of all deformable barriers used for shock protocols.

Claims

Claims

1. A motor vehicle in a spatial reference frame comprising a longitudinal axis (X) along a direction of movement of the motor vehicle; a lateral axis (Y) perpendicular to the longitudinal axis (X), and a vertical axis (Z) perpendicular to the longitudinal axis (X) and to the lateral axis (Y), the motor vehicle comprising a heat source (S) and a cooling system for cooling the heat source (S), the cooling system comprising: - a radiator (R); - at least one circulation pump (P); - at least one heat exchanger (HE); - at least one turbine (T) connected to a generator (G); - at least one first cooling circuit (Cl) comprising a first fluid, connecting the radiator (R) to said pump (P), then to said heat exchanger (HE), then to said turbine (T);and - at least one second cooling circuit (C2) comprising a second fluid, connecting said heat exchanger (HE) to the source (S).;

2. Motor vehicle according to claim 1, characterized in that the generator (G) is connected to a battery (B).

3. Motor vehicle according to claim 2, wherein the battery (B) is a traction battery (B).

4. Motor vehicle according to any one of claims 1 to 3, characterized in that the radiator (R) has a honeycomb or parallel tube structure with orifices arranged longitudinally along the longitudinal axis (X).

5. Motor vehicle according to any one of claims 1 to 4, characterized in that the heat exchanger (HE) has a honeycomb or parallel tube structure with orifices arranged longitudinally along the longitudinal axis (X).

6. Motor vehicle according to any one of claims 1 to 5, characterized in that the first fluid comprises ammonia or bioethanol.

7. Motor vehicle according to any one of claims 1 to 6, characterized in that the second fluid comprises a coolant.

8. Motor vehicle according to any one of claims 1 to 7, characterized in that it comprises: - two first cooling circuits (Cl) each connecting said radiator (R) to a respective pump (P), then to a respective heat exchanger (HE), then to a respective turbine (T); - two second cooling circuits (C2) each connecting said respective heat exchanger (HE) to the source (S).

9. Motor vehicle according to any one of claims 1 to 8, characterized in that the heat source (S) comprises an internal combustion engine and / or an electric machine.

10. Method for cooling a heat source of a motor vehicle according to any one of claims 1 to 9, comprising the following steps: - setting up at least one first cooling circuit (Cl) comprising a first fluid, connecting the radiator (R) to said pump (P), then to said heat exchanger (HE), then to said turbine (T); and at least one second cooling circuit (C2) comprising a second fluid, connecting said heat exchanger (HE) to the source (S); and - actuating said pump (P) so as to cool the heat source (S).

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