De-icing/defogging device for electrically propelled vehicles

Abstract

A device and a method for defogging and/or defrosting a glazing unit of a motor vehicle with a partially or totally electric propulsion system is disclosed. The device comprises means (1) for cooling a coolant fluid, using at least one electric current source, and a thermal battery (2), the device being configured to allow, in certain phases, the cooling of the coolant fluid by the cooling means (1) and the storage of cold from the coolant fluid in the battery (2), and, in other phases, the release of cold from the battery (2) into the coolant fluid.

Claims

1. A device for defogging and/or defrosting a motor vehicle with a partially or totally electric propulsion system, wherein said device comprises means for cooling a coolant fluid using at least one electric current source, and a thermal battery, wherein the thermal battery comprises a phase change material whose phase change temperature is in the range from 0 to −5° C. and wherein the phase change material is encapsulated in tubes in the thermal battery, said device being configured to allow, in certain phases, the cooling of said coolant fluid by said cooling means and the storage of cold from said coolant fluid in said battery, and, in other phases, the release of cold from said battery into said coolant fluid, wherein said device further comprises a heat exchanger through which said coolant fluid and a flow of air for defrosting/defogging can pass, said exchanger enabling a heat exchange to be provided between said air flow and said coolant fluid, wherein said device comprises a first branch, which is further defined as a thermal source branch, comprises the cooling means and the thermal battery in series, and a second branch, which is further defined as a defrosting/defogging branch, comprises said heat exchanger, and wherein said device is configured for serial fluid communication in the thermal source branch and in the defrosting/defogging branch.

2. The device as claimed in claim 1, wherein the cooling means are thermoelectric cooling devices.

3. The device as claimed in claim 1, wherein the phase change material is a eutectic whose latent heat of phase change is greater than or equal to 300 kJ/kg.

4. The device as claimed in claim 1, comprising a third branch, which is further defined as a charging branch for said coolant fluid.

5. The device as claimed in claim 4, comprising means for controlling the circulation of the coolant fluid in each of said branches, for the selective provision of: serial fluid circulation in the thermal source branch and in the charging branch, and serial fluid circulation in the thermal source branch and in the defrosting/defogging branch.

6. The device as claimed in claim 5, wherein said control means are composed of a three-way valve, each of said branches being connected to one of the channels of the three-way valve at one of its ends.

7. A method for defogging and/or defrosting a glazing unit of a motor vehicle with a partially or totally electric propulsion system, wherein: means for cooling a coolant fluid, based on at least one electric current source, are provided, together with a thermal battery, arranged in series with said means for cooling, and a heat exchanger through which said coolant fluid and a flow of air for the defrosting/defogging of said vehicle can pass, said exchanger enabling a heat exchange to be provided between said air flow and said coolant fluid, in certain phases, cold from said coolant fluid is stored in said battery while said coolant fluid is cooled by said cooling means, in other phases, the coolant fluid is cooled by releasing cold from said battery and sending it to said coolant fluid and is circulated in series through said cooling means and through said exchanger, wherein the thermal battery comprises a phase change material whose phase change temperature is in the range from 0 to −5° C. and wherein the phase change material is encapsulated in tubes in the thermal battery.

8. The method as claimed in claim 7, wherein: in the phases in which said coolant fluid is cooled by the cooling means, the coolant fluid is made to circulate through said cooling means and through said exchanger, and in the phases in which cold is released from said thermal battery, the coolant fluid is made to circulate through said battery and said exchanger.

9. The method as claimed in claim 8, wherein: a mode in which the vehicle is connected to a domestic electricity supply, which is further defined as a stationary mode, and a mode in which the propulsion system of the vehicle is active, which is further defined as a drive mode, are detected, and if said stationary mode is detected, said cooling means are supplied with power from said domestic electricity supply.

10. The method as claimed in claim 9, wherein said cooling means are composed of a thermoelectric cooling device, and the following are provided: three branches for the circulation of said coolant fluid, wherein: a first branch, which is further defined as a thermal source branch, comprises said thermoelectric cooling device and the thermal battery in series, a second branch, which is further defined as a defrosting/defogging branch, comprises said heat exchanger, a third branch, which is further defined as a charging branch, an electric pump for circulating the coolant fluid in said branches, and an electric fan for forcing the circulation of the air flow through said heat exchanger.

11. The method as claimed in claim 10, wherein, in stationary mode, cold is stored in the thermal battery by making the fluid circulate in a serial manner through the charging branch and through the thermal source branch, while the power is supplied to the thermoelectric cooling device, and no power is supplied to the fan.

12. The method as claimed in claim 10, wherein, in drive mode, the air passing through the heat exchanger is cooled by making the coolant fluid circulate in a serial manner through a thermal source branch and through a defrosting/defogging branch, while power is supplied to the fan and no power is supplied to the thermoelectric cooling device.

13. The method as claimed in claim 10, wherein, in drive mode, a discharged condition of the thermal battery is detected, and the air passing through the heat exchanger is cooled by making the coolant fluid circulate in a serial manner through a thermal source branch and through a defrosting/defogging branch, while power is supplied to the fan and to the thermoelectric cooling device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be more readily understood on consideration of the following description which is provided for guidance only and without limiting intent, accompanied by the appended drawings, in which:

(2) FIG. 1 is a schematic illustration of an embodiment of the device according to the invention, in a first operating mode,

(3) FIG. 2 is a schematic illustration of the device of FIG. 1 in a second operating mode, and

(4) FIG. 3 is a schematic illustration of the device of FIG. 1 in a third operating mode.

DETAILED DESCRIPTION

(5) As shown in FIGS. 1 to 3, the defrosting/defogging device according to the invention comprises means 1 for cooling a coolant fluid, for example water with added glycol, using at least one electric current source (not shown), and a thermal battery 2 forming a means for storing cold.

(6) Additionally, said device is configured to allow, on the one hand, in certain phases, the cooling of said coolant fluid by said means 1 for cooling the coolant fluid and the extraction of cold from said coolant fluid for storage in said thermal battery, as shown in FIG. 1, and, on the other hand, in other phases, a return of heat (in this case, a release of cold) from said thermal battery into said coolant fluid, as shown in FIGS. 2 and 3.

(7) The cooling means 1 are, for example, a thermoelectric cooling device, operating by the Peltier effect, which uses electrical energy to create temperature differences between two elements, one of which is heated while the other is cooled. A system of this type is markedly more economical in terms of size and energy consumption than a conventional system for producing cold using an on-board cooling machine comprising a compressor, a condenser and an evaporator. It is more suitable for the function of drying the defrosting/defogging air, which it is desirable to provide in response to the stated technical problem.

(8) As regards the thermal battery 2, this may be a latent heat battery. A battery of this type is configured so that the coolant fluid can pass through it. It is also provided with a phase change material (PCM) encapsulated in the battery so that a heat exchange can take place between the PCM and the coolant fluid. The PCM is chosen in such a way that, when the coolant liquid passes through the battery, and this liquid is provided in a sufficiently cold state, that is to say at a temperature below the PCM solidification temperature, the PCM solidifies and therefore surrenders heat by a phase change from liquid to solid, which is equivalent to storing cold. The latent energy of phase change can also be used to cool the coolant fluid by making the latter circulate in the battery when it is at a temperature higher than the melting point of the PCM and the battery has stored sufficient cold.

(9) In order to be most suitable for the defrosting/defogging function, the phase change material, which is encapsulated in tubes in the thermal battery, is chosen so as to have a phase change temperature in the range from 0 to −5° C., and preferably close to −3.7° C., so as to provide a temperature in the heat exchanger within the range from 0 to 8° C. The PCM must also have the highest possible latent heat of phase change in order to provide a high storage density. For this purpose, the material preferred for use is a eutectic having a latent heat of 312 kJ/kg.

(10) The device may further comprise a heat exchanger 3, through which said coolant fluid and the flow of air to be dehumidified can pass, said exchanger enabling a heat exchange to be provided between the defrosting/defogging air and said coolant fluid. The exchanger may be, for example, a cold exchanger of the tube and spacer type, that is to say one comprising a bundle of parallel tubes through which said coolant fluid flows, said tubes being connected at their ends to manifolds which each have an inlet and an outlet for the coolant fluid. Spacers, through which the air flow passes, are provided between the tubes. Said tubes and spacers are configured to cool the air flow which contacts the spacers, using the cold circulating in the tubes.

(11) Said device can be placed in a housing of an air conditioning system (not shown), with a fan or blower 9, enabling an air flow to be forced through said exchanger for use in defrosting/defogging.

(12) According to the illustrated exemplary embodiment, said device according to the invention comprises three branches for the circulation of said coolant fluid.

(13) The first branch 4, called the thermal source branch, comprises the means 1 for cooling the coolant fluid and the thermal battery 2 in series. It may also comprise a pump 5 for the circulation of said coolant fluid, for example a pump fitted in series with the thermal battery 2 and the cooling means 1, notably in this order.

(14) The second branch 6, called the defrosting/defogging branch, comprises said heat exchanger 3.

(15) Said device further comprises means 7 for controlling the circulation of the coolant fluid in each of said branches, for the selective provision of: serial fluid circulation through the third branch 8, called the charging branch, and through the thermal source branch 4, serial circulation through the thermal source branch 4 and through the defrosting/defogging branch 6.

(16) The control means may be, for example, a three-way valve, each of said branches being connected to one of the channels of the three-way valve at one of its ends 4a, 6a, 8a. Said branches 4, 6, 8 are also interconnected at a common point 10 placed at their ends 4b, 6b, 8b.

(17) Said device is configured to allow the total or partial application of the method according to the invention, which is described below.

(18) According to this method, as mentioned above, in certain phases, cold from said coolant fluid is stored in said battery 2 while said coolant fluid is cooled by said cooling means 1, as shown in FIG. 1. In other phases, the coolant fluid is cooled by releasing cold from said battery 2, as shown in FIGS. 2 and 3. Regardless of the operating phase, the coolant fluid circulates through said cooling means 1. The thermal battery 2 is constantly connected to said cooling means 1 and can be positioned upstream of said cooling means 1, according to the direction of flow of the coolant fluid in the thermal source branch 4, as shown in FIGS. 1 to 3.

(19) In the phases in which cold is returned by said thermal battery 2, the air flow for defrosting/defogging can be cooled by making the coolant fluid circulate through said battery 2 and said exchanger 3, as shown in FIG. 2.

(20) It is also possible to cool the air flow passing through the heat exchanger by making the coolant fluid circulate through said means 1 for cooling the coolant fluid and through said exchanger 3, as shown in FIG. 3.

(21) Thus a mode for storing cold and two modes for cooling the air passing through the heat exchanger 3 are available.

(22) Additionally, a mode in which the vehicle is connected to a domestic electricity supply, called the stationary mode, and a mode in which the propulsion system of the vehicle is active, called the drive mode, are distinguished.

(23) If said stationary mode is detected, said cooling means 1 are supplied with power from said domestic electricity supply to cool said coolant fluid, as shown in FIG. 1.

(24) The term “domestic electricity supply” signifies, for example, the low-tension electric supply of a residence or charging station, such as a three-phase alternating electricity supply providing electric current at 220 V to 240 V and at 50 or 60 Hz between phase and neutral.

(25) On the other hand, in drive mode, said cooling means 1 can be supplied with power from a current source on the vehicle, notably a current source included in the vehicle propulsion system.

(26) This source may be a high-tension electricity system of the vehicle, for example a system providing power at 400 V d.c. and connecting the electric machine which propels the vehicle to batteries known as traction batteries. It may also be a low-tension electricity system of the vehicle, for example a system providing power at 12 V d.c. and serving to supply various electrical components of the vehicle from a low-tension battery.

(27) More generally, in stationary mode the various pieces of electrical equipment included in the defrosting/defogging device according to the invention, such as the pump 5 and/or the fan 9, may be supplied from said domestic current source, whereas in drive mode they are supplied from said vehicle current source.

(28) In greater detail, as shown in FIG. 1, in stationary mode, cold can initially be stored in the thermal battery 2 by making the fluid circulate in a serial manner through the charging branch 8 and through the thermal source branch 4, notably through the three-way valve 7, whose channels connected to said branches 4, 8 are set to be open, while the channel of said valve 7 connected to the defrosting/defogging branch 6 is closed. Additionally, the cooling means 1 are supplied with power from the domestic current source, whereas no power is supplied to the fan 3. The pump 5 is also supplied from the domestic current source.

(29) In drive mode, as shown in FIG. 2, the defrosting/defogging air can be cooled by cooling the air passing through the heat exchanger 3 by circulating the coolant fluid through the thermal source branch 4 and through the defrosting/defogging branch 6, notably through the three-way valve 7, whose channels connected to said branches 4, 6 are set to be open, while the channel of said valve 7 connected to the charging branch 8 is closed. Additionally, the pump 5 and, if necessary, the fan 9 are supplied with power, whereas no power is supplied to the cooling means 1. Thus the current drawn from the electric batteries is minimized, while the cold released from the thermal battery 2 is used.

(30) Also in drive mode, it is possible to detect partial or total discharged conditions of the thermal battery 2, while still cooling the air passing through the heat exchanger 3, by making the coolant fluid circulate in a serial manner through the thermal source branch 4 and through the defrosting/defogging branch 6, notably through the three-way valve 7, whose channels connected to said branches 4, 6 are set to be open, while the channel of said valve 7 connected to the charging branch 8 is closed. Additionally, the pump 5 and the thermoelectric cooling device 1 are supplied with power, together with the fan 9 if necessary. Thus, particularly if the demand for defrosting/defogging is prolonged and if the state of charge of the electric batteries of the vehicle permits, it is possible to prolong the cooling of the defrosting/defogging air, even if the thermal battery 2 has no more cold, or very little cold, to supply.