VEHICLE INCLUDING A THERMOCHEMICAL ENERGY STORAGE SYSTEM

Abstract

The invention relates to a motor vehicle comprising a passenger compartment, an electric traction machine, a battery pack, at least one power electronics unit, and a cooling radiator, a thermochemical system (10) comprising a first enclosure called a reservoir (1), containing gas in liquid phase and a second enclosure called a reactor (2) containing reactive salts, the two enclosures being configured to be selectively placed in fluid communication at least via a control solenoid valve (3), the reactor being able to be heated by supplying calories from the operation of the electric traction machine, and / or the battery pack, and / or the power electronics unit, and the reactor is capable of delivering calories, following an opening of the control solenoid valve, to the passenger compartment of the vehicle, and / or the battery pack, and / or the cooling radiator of the vehicle.

Description

Title of the invention: VEHICLE COMPRISING A THERMO-CHEMICAL ENERGY STORAGE SYSTEM

[0001] The present invention relates to a motor vehicle comprising a system for storing and transferring energy in thermal form, in particular by thermochemical means.

[0002] According to a similar formulation, the present invention relates to a system for storing and transferring energy in thermal form, in particular by thermochemical means, in a motor vehicle.

[0003]

[0004] There are currently several potential ways to reuse wasted thermal energy in electric or hybrid vehicles: - the heat lost by the electric motor is transported using a heat transfer fluid to be used to heat the battery and / or the passenger compartment, - the heat lost by the power electronics is transported using a heat transfer fluid to be used to heat the battery and / or the passenger compartment, - the heat lost by the battery is transported using a heat transfer fluid to be used to heat the passenger compartment.

[0005] The disadvantage of these solutions is their rare use due to the fact that a very specific circumstantial case is required to benefit from them, namely a need for cooling on one side (on the electric machine or the battery) and at the same time a need for heating on another part or the passenger compartment. When these conditions are not met, the energy is then lost because the above solutions are not applicable.

[0006] Furthermore, the rapid charging of electric vehicles involves a very significant energy flow entering the battery and the resulting heating must be evacuated by the vehicle's cooling system. It follows that the sizing of the vehicle's cooling system must be revised upwards to be compatible with the thermal management of the rapid charging phases.

[0007] The inventors sought to improve the flexibility of the vehicle's thermal management system and to propose a solution for optimizing the sizing of the cooling components, in particular by temporarily storing thermal energy to then evacuate it.

[0008] To this end, the present invention proposes a motor vehicle comprising a passenger compartment, at least one electric traction machine, at least one battery pack ... at least one power electronics unit, and at least one cooling radiator, the vehicle comprising a thermochemical system comprising a first enclosure called a reservoir, containing gas partly in liquid phase and at least one second enclosure called a reactor containing reactive salts, in liquid or solid form, the two enclosures being configured to be selectively placed in fluid communication at least via a control solenoid valve, the reactor can be heated by supplying calories from the operation of the electric traction machine, and / or the battery pack, and / or the power electronics unit, and / or a heating resistor, with gas desorption leading to an increase in the quantity of liquid in the reservoir, and in that the reactor is capable of delivering calories, following opening of the control solenoid valve, to the passenger compartment of the vehicle, and / or the battery pack,and / or the vehicle's cooling radiator, with absorption or adsorption of gas leading to a reduction in the quantity of liquid in the tank.

[0009] Thanks to the provisions promoted above, it is possible to store a significant quantity of energy in thermochemical form in the gas reservoir in liquid phase, with the aim of being able to reuse this energy in a deferred manner.

[0010] Advantageously, the triggering of the energy recovery is selectively controlled by one of the computers on board the vehicle, by opening the control solenoid valve. Thus the on-board electronic system can determine the appropriate moment to recover the calories in order to supply them to one of the vehicle's subsystems or in order to evacuate them to the outside via the radiator.

[0011] The energy storage process may correspond to a rolling phase of the vehicle. The energy storage process may alternatively correspond to a rapid charging phase of the vehicle (when stationary).

[0012] Such thermochemical systems exploit the properties of a reversible thermochemical reaction.

[0013] To store energy, a heat input to the reactor is used. In the reactor, heating the reactive salts causes gas desorption and the gas that was fixed in the reactive salts is then released, the heated gas is directed under pressure through a connecting pipe towards the reservoir and the gas then condenses in the reservoir which is colder. To conserve the energy stored in the reservoir, the connecting pipe must then be closed.

[0014] Conversely, to recover energy, that is to say to release energy, while the reactor is not subjected to a supply of calories, it is sufficient to reopen the passage of the pipe, by opening the control solenoid valve, then the gas stored in the tank vaporizes and goes towards the reactor. In the reactor then occurs a strongly exothermic reaction during which the product reactive, including reactive salts, absorbs the gas, and a significant amount of calories is delivered outside the reactor.

[0015] According to a typical example, the gas of the thermochemical system may be ammonia and the reactive salts may be, for example, calcium chloride or barium chloride.

[0016] In practice, at least one heat exchanger device is provided thermally coupled with the reactor described above and supporting circulation of a conventional heat transfer fluid.

[0017] In an auxiliary manner, it should be noted that when the two enclosures are put into communication, the liquid gas contained in the tank vaporizes, which absorbs a certain quantity of heat, so that the tank cools, and frigories can be recovered at this location.

[0018] According to one embodiment, the thermochemical system is capable of storing at least 5 kilowatt hours, preferably at least 10 kilowatt hours.

[0019] Advantageously, the system can store a substantial amount of energy which can correspond to the cumulative energy flow of the cooling requirement of the battery pack when the latter is subjected to rapid recharging, typically with a recharging flow of at least 50 kilowatts, often at least 75 kilowatts.

[0020] Such a recharging sequence can cause a thermal flux to be evacuated of the order of 15 kW for example for 20 minutes.

[0021] This allows the cooling system to be dimensioned as accurately as possible. The cooling radiator may be insufficient to overcome the thermal peak associated with rapid recharging, but temporary storage in the thermochemical system allows the heat removal to be spread out over time.

[0022] In one embodiment, the gas is ammonia and the reactive salts comprise barium chloride or calcium chloride. The physical properties of ammonia are suitable for use at the target temperatures of automotive applications, particularly in the range between 0 degrees Celsius and 80°C.

[0023] According to one embodiment, the thermochemical system may further comprise at least a first heat exchanger in thermal coupling with the reactor. In this first heat exchanger, calories are exchanged between the core of the reactor where the reversible chemical reaction mentioned above occurs, and a conventional heat transfer fluid which transports the calories to other systems or subsystems of the vehicle. It may be a tubular type exchanger, the tubes conveying the heat transfer fluid passing through the interior of the reactor, for example glycolated water.

[0024] According to one embodiment, the thermochemical system may further comprise a second heat exchanger in thermal coupling with the reservoir. The reservoir is formed as a bottle, the second heat exchanger may be formed such as a coil that wraps helically around the bottle or an exchanger positioned inside the bottle near the gas outlet to recover frigories when the bottle cools. A conventional heat transfer fluid, such as glycolated water, circulates in the coil.

[0025] According to one embodiment, the thermochemical system may further comprise a non-return valve mounted in parallel with the control solenoid valve. The non-return valve allows gas to pass from the reactor to the tank but blocks the passage of gas from the tank to the reactor.

[0026] As a result, an automatic storage function is obtained in passive mode without any particular control, when the first heat exchanger supplies calories to the reactor.

[0027] According to one embodiment, the vehicle comprises at least one on-board computer responsible for controlling the control solenoid valve, as a function of at least the operating circumstances of the vehicle, the outside temperature, the forward speed of the vehicle, the temperature of the battery, the temperature of the electric machine.

[0028] Cleverly, one can choose the best combinations to store thermal energy that would otherwise be lost, and to later reuse the stored energy as effectively as possible for the most relevant use. This strategy makes it possible to optimize the overall energy consumption of the vehicle.

[0029] Furthermore, according to one option, the control solenoid valve is of the normally closed type. It is therefore necessary for the on-board computer to supply energy to the solenoid valve to open the fluid communication passage in the pipe which connects the tank and the reactor. Since no energy is spent to keep the valve closed, the energy storage in the tank does not consume electricity and is not limited in duration.

[0030] The invention further relates to a method implemented in a motor vehicle as described above, characterized in that the method provides a first phase of energy storage coinciding with a rapid recharging sequence of the battery pack, and a second subsequent phase of energy destocking.

[0031] Thus, part of the cooling heat flow generated by the rapid recharging sequence can subsequently be released to the radiator, or to the passenger compartment if the temperature is low.

[0032] This can have a beneficial impact on the sizing of the cooling radiator, it does not absorb all the energy flow induced by the search for fast in real time.

[0033] The invention further relates to a method implemented in a motor vehicle. as previously described, characterized in that the method provides - a first phase of energy storage triggered during a rolling sequence for a duration at least equal to a predetermined duration, - a second phase of energy release, triggered later when the vehicle starts from cold, the release being directed towards the passenger compartment in order to warm it up.

[0034] Thus, when the vehicle starts from cold, the vehicle's passenger compartment or even the battery pack can be heated with calories that were stored during the previous cycle.

[0035] We note in fact that the duration of energy storage in the bottle is not limited, there is no self-discharge, the quantity of energy retained does not decrease over time.

[0036] Expressed differently, in view of the use cases described above, the thermochemical system acts as a buffer storage of heat energy with very interesting convenience of use, in terms of quantity stored and storage duration.

[0037] The invention further relates to a method implemented in a motor vehicle as described above, characterized in that the method provides in an energy destocking phase, calories are recovered on the first exchanger coupled to the reactor, and frigories are simultaneously recovered on the second exchanger coupled to the tank. By means of an ad hoc hydraulic circuit, these frigories can contribute to the air conditioning function of the vehicle.

[0038] Beyond the three use cases presented above, the system has such flexibility that other use cases can be considered, without limitation.

[0039] 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] is a schematic side view of a motor vehicle according to the present invention; [Fig.2] shows an exemplary functional diagram of the thermochemical system implemented in the present invention; [Fig.3] schematically illustrates the organs and entities involved in thermal exchanges, according to initial circumstances of use [Fig.4] schematically illustrates the organs and entities involved in thermal exchanges, according to second circumstances of use [Fig.5] schematically illustrates the organs and entities involved in thermal exchanges, according to third circumstances of use.

[0040] In the various figures, the same references designate identical or similar elements.

[0041] In [Fig. 1], a vehicle 9 is shown schematically.

[0042] The vehicle in question 9 may be a passenger vehicle, a utility vehicle, a van, a truck, a bus, a recreational vehicle, etc.

[0043] The vehicle in question 9 comprises a powertrain 18. The powertrain may comprise an electric traction motor (electromotive group), and / or an internal combustion engine. Indeed, the vehicle 9 may be a 100% electric vehicle or a hybrid vehicle, without excluding a conventional vehicle with a thermal engine. In the case there is an electric powertrain, the vehicle 9 comprises a traction battery 5.

[0044] In the context of the present invention, the vehicle 9 is equipped with a thermochemical system 10 which will be described in detail later.

[0045] The vehicle 9 comprises a passenger compartment HAB of numerical reference 7, at least one electric traction machine MEL of numerical reference 6, at least one battery pack BATT of numerical reference 5, at least one power electronics unit, and at least one cooling radiator 8.

[0046] In addition, the vehicle comprises an on-board charger 11, called in the jargon of the trade OBC ('On Board Charger').

[0047] The battery pack 5 includes a battery management computer 12 called in the jargon of the trade BMS ('Battery Management System').

[0048] The vehicle 9 comprises a plurality of on-board computers, including in particular an on-board computer referenced 4 which will be of particular interest in what follows.

[0049] As illustrated in [Fig.2], the thermochemical system 10 comprises a first enclosure called reservoir 1, containing gas partly in liquid phase and a second enclosure called reactor 2 containing reactive salts, in liquid or solid form.

[0050] In tank 1, the gas is ammonia, in liquid IL and gaseous IG form, the quantity of gas molecules contained in the liquid being much greater than that contained in the gas part. In reactor 2, there are reactive salts which are based on calcium chloride or barium chloride.

[0051] In the general architecture of the vehicle, the tank 1 and the reactor 2 can be placed side by side, or close to each other to have a short pipe length. Optimizing the placement of the components can lead to installing the reactor and the tank at a distance, the operation is not substantially affected.

[0052] The two enclosures 1, 2 are configured to be selectively placed in fluid communication by means of a pipe 30 on which at least one control solenoid valve 3 is arranged. The pipe 30 can be equipped with a thermal insulation sheath if it has a certain length.

[0053] When the solenoid valve 3 is open, gas can flow between the two enclosures (namely the tank and the reactor) whereas when the solenoid valve is closed, it prevents any gas from flowing between the two enclosures.

[0054] The control solenoid valve 3 is controlled by the computer 4. For example, the control solenoid valve is of the normally closed type. Such a solenoid valve is known per se and is therefore not described in detail here.

[0055] The computer 4 controls the control solenoid valve, as a function of at least the operating circumstances of the vehicle, the outside temperature, the forward speed of the vehicle, the temperature of the battery, the temperature of the electric machine.

[0056] According to one option, the solenoid valve 3 must be controlled to authorize an energy storage sequence. In addition, the solenoid valve 3 must be controlled to trigger an energy release sequence.

[0057] An energy storage sequence causes, in the pipe 30, a circulation of gas in the direction of the arrow FL. An energy release sequence causes, in the pipe 30, a circulation of gas in the direction of the arrow F2.

[0058] The thermochemical system 10 is associated with one or more heat exchangers.

[0059] More precisely, a first heat exchanger 51 is provided in thermal coupling with the reactor 2.

[0060] In this first heat exchanger, calories are exchanged between the core of the reactor where the reversible chemical reaction mentioned above occurs, and a conventional heat transfer fluid which transports the calories to other systems or subsystems of the vehicle.

[0061] According to one example, the first heat exchanger 51 may be a tubular type exchanger, the tubes conveying the heat transfer fluid passing through the interior of the reactor, for example glycolated water.

[0062] In addition, in the illustrated example, the thermochemical system may further comprise a second heat exchanger 52 in thermal coupling with the reservoir. Since the reservoir is formed as a bottle, the second heat exchanger is formed as a coil that winds helically around the bottle or an exchanger positioned inside the bottle close to the gas outlet to recover frigories when the bottle cools. A conventional heat transfer fluid, such as glycolated water, circulates in the coil.

[0063] It is possible to provide several reactors, such as for example a second reactor 21 coupled to another heat exchanger 53.

[0064] Optionally, a heating resistor 55 is also provided in thermal coupling with the reactor 2. This heating resistor can be supplied with current electrical by the electrical network when it has excess energy, for example in certain conditions of electrical regenerative braking.

[0065] Optionally, it can be provided as a non-return valve 34 arranged in parallel with the solenoid valve 3 in order to authorize an energy storage sequence in passive mode (without specific command to open the solenoid valve).

[0066] The non-return valve 34 allows the passage of gas from the reactor to the tank if the pressure increases on the reactor side. On the other hand, when the pressure in the tank drops, the non-return valve 34 closes and the gas cannot return from the tank to the reactor.

[0067] Turning to [Fig.3], a cruising driving configuration for an electric vehicle is illustrated.

[0068] The MEL 6 electric traction machine must be cooled and the cooling circuit extracts calories from the electric machine subsystem.

[0069] Similarly, the BATT 5 battery pack must be cooled and the cooling circuit extracts calories from the battery pack subsystem. It is noted that the battery pack can also benefit from cooling by means of a refrigerant loop, for example a heat pump circuit, which takes calories from the battery and rejects them to the radiator.

[0070] Pipes 14 transport the calories in the form of a circulation of conventional heat transfer fluid such as glycolated water. It is noted that the pipes 14 can be equipped with selection valves, single valve, three-way valve, four-way valve, as known per se, therefore not shown or described in detail here.

[0071] As known, the calories to be evacuated are directed towards the cooling radiator 8. Depending on the need and the outside temperature, the calories can also be directed in part towards the passenger compartment HAB 7 of the vehicle.

[0072] Advantageously, the calories to be evacuated can also be directed towards the thermochemical energy storage system 10 which has been described in the preceding paragraphs, according to circumstances, logic and adapted decision criteria.

[0073] It is noted that calories may also have to be evacuated concerning one or more power electronic modules, in particular for example the power electronics 13 which controls the electric machine.

[0074] The supply of calories to the reactor 2 can also be done in electrical form via the use of the aforementioned heating resistor 55. Under regenerative braking conditions, for the part which exceeds the current acceptance of the battery during recharging, the remaining current can be directed to the electrical heating resistor 55, which makes it possible to store this energy in thermochemical form instead of simply losing it.

[0075] Turning to [Fig.4], a cycle start configuration is illustrated of use of the electric vehicle in cool or cold temperatures. It is assumed that the previous driving cycle has allowed energy to be stored in the thermochemical system 10. Under these conditions, when the user gets into the vehicle, the on-board electronics, depending on the temperature of the passenger compartment and the temperature desired by the user, can decide to recover energy from the tank 1 and then opens the solenoid valve 3 to cause the exothermic reaction in the reactor 2. The first heat exchanger takes these calories and directs them to the passenger compartment 7. The supply of calories to the passenger compartment is rapid, a few seconds are enough.

[0076] A similar process can take place for the battery pack 5 which may need to be conditioned at medium temperature to operate optimally before it is necessary to cool it a little later. In a manner analogous to what has been explained for the passenger compartment, the thermochemical system can be used to provide calories to the battery pack in the very first moments of the operating cycle.

[0077] Turning to [Fig.5], a rapid charging configuration (solid lines) and a delayed discharge configuration of thermal energy that has been temporarily stored by means of the charging sequence (dotted lines) are illustrated on the one hand.

[0078] As already mentioned in the introductory section, rapid charging of an electric vehicle battery pack involves a significant power transfer. It is now common to find charging stations and vehicles compatible with charging powers of 75 kW, 100 kW, 150 kW, 200 kilowatts and this can even go up to 300 kilowatts.

[0079] The charging process is accompanied by a loss of energy by Joule effect, particularly inside the battery. This energy must be evacuated in order not to let the temperature of the battery pack rise too high. This energy can of course be evacuated by the cooling radiator 8.

[0080] Cleverly according to the present invention, the thermal energy to be evacuated is distributed towards two destinations: firstly the cooling radiator 8 of course, but also the thermochemical system 10 which will accept a significant supply of calories.

[0081] Whereby, provided that the thermochemical system is prepared for a rapid recharge sequence, that is to say in practice that the tank is rather empty, the distribution of calories both on the radiator and on the reactor of the thermochemical system makes it possible not to increase the size of the cooling radiator.

[0082] To prepare the thermochemical system for maximum acceptance of thermal energy, it may be provided that when the vehicle navigation system indicates a fast charging station destination, then the on-board computer 4 causes energy to be released into the thermochemical system in preparation for new storage in the short term.

[0083] The on-board electronic systems can also prepare the thermochemical system in this way when the vehicle takes a long motorway route.

[0084] It should be noted that it can be provided that, if it is impossible to store energy in the thermochemical system, then the on-board charger OBC 11 will have to limit the charging power acceptance.

Claims

Claims

1. Motor vehicle (9) comprising a passenger compartment (7), at least one electric traction machine (6), at least one battery pack (5), at least one power electronics unit, and at least one cooling radiator (8), characterized in that the vehicle comprises a thermochemical system (10) comprising a first enclosure called a reservoir (1), containing gas partly in liquid phase and at least one second enclosure called a reactor (2) containing reactive salts, in liquid or solid form, the two enclosures being configured to be selectively placed in fluid communication at least via a control solenoid valve (3), the reactor can be heated by supplying calories from the operation of the electric traction machine, and / or the battery pack, and / or the power electronics unit,and / or a heating resistor (55) with gas desorption leading to an increase in the quantity of liquid in the tank, and in that the reactor is capable of delivering calories, following opening of the control solenoid valve (3), to the passenger compartment of the vehicle, and / or the battery pack, and / or the cooling radiator of the vehicle, with absorption or adsorption of gas leading to a reduction in the quantity of liquid in the tank.,

2. Motor vehicle according to claim 1, characterized in that the thermochemical system is capable of storing at least 5 kilowatt hours, preferably at least 10 kilowatt hours.

3. A motor vehicle according to any one of claims 1 to 2, characterized in that the gas is ammonia and the reactive salts comprise barium chloride or calcium chloride.

4. Motor vehicle according to any one of claims 1 to 3, further comprising at least one first heat exchanger (51) in thermal coupling with the reactor (2).

5. Motor vehicle according to any one of claims 1 to 4, further comprising at least one second heat exchanger (52) in thermal coupling with the tank (1).

6. A motor vehicle according to any one of claims 1 to 5, further comprising a non-return valve (34) mounted in parallel with the control solenoid valve (3).

7. Motor vehicle according to any one of claims 1 to 6, comprising at least one on-board computer (4) responsible for controlling the control solenoid valve, as a function at least of the operating circumstances of the vehicle, the outside temperature, the forward speed of the vehicle, the temperature of the battery, the temperature of the electric machine.

8. Method implemented in a motor vehicle according to any one of claims 1 to 7, characterized in that the method provides a first phase of energy storage coinciding with a sequence of rapid recharging of the battery pack, and a second subsequent phase of energy de-storage.

9. Method implemented in a motor vehicle according to any one of claims 1 to 7, characterized in that the method provides - a first phase of energy storage triggered during a driving sequence for a duration at least equal to a predetermined duration, - a second phase of energy destocking, triggered subsequently when the vehicle starts from cold, the destocking being directed towards the passenger compartment in order to heat it.

10. Method implemented in a motor vehicle according to any one of claims 1 to 7, characterized in that in an energy destocking phase, calories are recovered on the first exchanger coupled to the reactor, and frigories are simultaneously recovered on the second exchanger coupled to the tank.

Images