MOTOR VEHICLE WITH AIR EXTRACTION BETWEEN FLOOR MAT AND FLOOR FORMING BATTERY BOX COVER

Abstract

An electric motor vehicle comprising a housing containing a traction battery for the vehicle, which is positioned flat under a floor plate (20) of the vehicle's passenger compartment forming the cover of this housing, a floor mat covering the floor plate (20), a vehicle passenger compartment air conditioning unit (30), and comprising an intermediate safety space formed between the floor mat and the floor plate (20), which, in the event of significant heating of the traction battery, is connected to the air conditioning unit (30) to draw in the volume of air present in this intermediate space. Figure 2

Description

Title of the invention: MOTOR VEHICLE WITH AIR EXTRACTION BETWEEN FLOOR MAT AND FLOOR FORMING A BATTERY BOX LID

[0001] The present invention relates to a motor vehicle equipped with a passenger compartment floor forming the cover of a traction battery box located below, as well as a method for securing such a vehicle.

[0002] The battery of electric traction motor vehicles is now often arranged flat under the floor of the passenger compartment in order to benefit from a large surface area allowing a large mass to be installed in the vehicle at a low height to maintain a low center of gravity.

[0003] The batteries are housed in a rigid, enclosed casing that provides mechanical protection for the internal components to protect and withstand various impacts that may occur to the vehicle during accidents. The casing generally comprises a flat lower tray forming the underside of the vehicle, containing a tray for receiving a cooling fluid, a frame with housings for the electrochemical cells, and the various electrical connection and electronic control components.

[0004] A cover closes the top of the box to ensure a seal preventing the entry of pollutants such as water or dust, and the exit of fluids during incidents, such as acid leaks or fumes which can be highly toxic.

[0005] The underside of the vehicle's underbody tray meets a minimum ground clearance requirement to allow driving on various terrains. The aim is to minimize the overall thickness between the underside of the tray and the floor of the passenger compartment, which includes the battery, to maintain a sufficiently low floor while preserving maximum available volume to accommodate a battery with the highest possible charging capacity.

[0006] According to a known embodiment, an independent box is formed to receive the battery and closed by its sealed cover, which is fixed under the floor of the passenger compartment including its stiffening cross members, preserving a space between the cover and the floor forming an air gap thermally insulating the battery from this floor.

[0007] In this case, the total thickness between the floor and the underside of the vehicle, including the thicknesses of the two floor and lid sheets and the intermediate air gap, is relatively significant. Furthermore, the floor and lid form two overlapping sheets that add mass to the vehicle.

[0008] According to another known embodiment of an electric vehicle, a body is constructed including floor stiffening cross members, without providing the sheet metal fixed beneath these cross members to form the floor. The battery box, including a flat cover, is then fixed beneath the vehicle body, resting under the cross members, this cover thus forming the floor sheet metal.

[0009] Alternatively, the battery box cover may include floor stiffening crossbeams, the bottom of the passenger compartment having a large opening which then receives the box fixed around this opening to simultaneously form the vehicle floor and the stiffening of the body.

[0010] In these last two cases, the same sheet metal forms both the floor of the passenger compartment and the lid of the box, the superposition of two sheets is avoided, which reduces the mass, and gives a minimum thickness between the floor and the underside of the vehicle.

[0011] In general, battery boxes include an internal cooling system to dissipate the heat generated by the normal operation of the battery.

[0012] Furthermore, a known type of electric vehicle, described in particular by document US-A1-2004062955, comprises two successive compartments arranged flat beneath the passenger compartment floor. The front compartment contains a fuel cell, and the rear floor comprises, after a vertical partition equipped with thermal insulation, a battery powering an electric traction motor for the vehicle. Above the battery compartment, the rear floor has air inlet and outlet holes equipped with a fan, allowing air from the passenger compartment to be circulated into this compartment to cool the battery, and then returned to the passenger compartment.

[0013] In this way, air is taken from the passenger compartment which can be cooled by the air conditioning system for passenger comfort, to manage the temperature of the traction battery in order to optimize its performance.

[0014] However, for a passenger compartment floor forming the battery cover, during operating accidents, in particular during a thermal runaway of electrochemical cells, very hot gases delivering a significant amount of thermal energy are produced in the compartment, strongly heating the floor.

[0015] The vehicle passenger compartment floor is generally carpeted to provide comfort through thermal and sound insulation, and supports various equipment attached to it. Significant heating of the floor sheet metal, particularly with temperatures reaching 150°C, leads to serious problems, including vaporization of the floor paint, its joints, and the organic components of the floor mat, releasing toxic gases that are harmful to passengers.

[0016] In particular after a vehicle collision, toxic gases can inconvenience passengers remaining confined in the passenger compartment by causing a reduction in their vigilance or a loss of consciousness with major risks to their safety.

[0017] The present invention aims in particular to avoid these problems of the prior art.

[0018] To this end, it proposes an electric motor vehicle comprising a box containing a traction battery for this vehicle, which is arranged flat under a floor plate of the vehicle's passenger compartment forming the cover of this box, a floor mat covering the floor plate, and comprising an air conditioning unit for the vehicle's passenger compartment, this vehicle being remarkable in that it includes an intermediate safety space formed between the floor mat and the floor plate, which in the event of significant heating of the traction battery is connected to the air conditioning unit to draw in the volume of air present in this intermediate space.

[0019] An advantage of this motor vehicle is that in critical situations including a high temperature rise of the floor sheet metal, during a thermal runaway of the battery, air is drawn into the intermediate safety space both to cool this space by bringing in fresh air which delays the heating of the floor mat placed above and of materials such as the paint and the floor joints, and to draw away any toxic gases which might begin to appear from a decomposition of nearby components.

[0020] This provides a delay before significant heating of the floor mat and other materials, resulting in critical temperatures that release toxic gases, ensuring protection for the passengers during this period, allowing them in particular to leave the vehicle more easily.

[0021] The motor vehicle according to the invention may further comprise one or more of the following characteristics, which may be combined with each other.

[0022] Advantageously, the aspiration of the air volume from the intermediate space uses a fan from the air conditioning unit intended to draw outside air from the passenger compartment.

[0023] In this case, advantageously the vehicle includes two lateral ducts placed on the floor mat, which are connected to the air conditioning unit by a central duct.

[0024] Moreover, advantageously the side ducts have ends which open out along the longitudinal direction of the vehicle substantially in the middle of the passenger compartment.

[0025] Advantageously, the vehicle includes movable flaps between the air conditioning unit and the intermediate space which, depending on their positions, connect the air conditioning unit with the vehicle's passenger compartment or with this intermediate space.

[0026] According to one embodiment, the movable shutters include motors which are controlled.

[0027] According to another embodiment, the movable flaps have a geometry comprising a pivot axis which automatically tilts them without motorization to connect the air conditioning unit with the intermediate space when this unit generates a depression.

[0028] Advantageously, the intermediate space has a thickness between 3 and 30mm.

[0029] The invention also relates to a method for securing a motor vehicle comprising any of the preceding characteristics, remarkable in that in the event of significant heating of the traction battery it controls a succession of suction sequences by the air conditioning unit.

[0030] The invention further relates to a method for securing a motor vehicle comprising any of the preceding characteristics, remarkable in that in the event of overheating of the traction battery due to a failure, water is introduced through the outside air intake of the air conditioning unit, while leaving open distribution flaps of this unit to conduct the water towards the intermediate space.

[0031] The invention will be better understood and other features and advantages will become more apparent upon reading the following description given by way of example, with reference to the accompanying drawings in which:

[0032] [Fig-1] is a vertical cross-sectional diagram along the longitudinal axis of a vehicle electric according to the invention comprising a battery box cover forming the floor of the passenger compartment;

[0033] [Fig.2] is a top view of the floor of this vehicle;

[0034] [Fig.3] is a cross-sectional view along a vertical plane of the floor of this vehicle with the battery underneath; and

[0035] [Fig.4] is a vertical cross-sectional view along the longitudinal axis of the canopy of this vehicle, showing the gas extraction and a water inlet.

[0036] The [Fig.1] shows a battery 2 fixed in a tray 4 made of a resistant sheet metal, comprising successively from the bottom a lower flat sheet metal of the tray 6, a battery cooling plate 8 including a heat exchange fluid circuit, a rigid frame 10 for holding the electrochemical cells 12, and electrical and electronic equipment 14 for connecting and controlling the battery.

[0037] A battery cover 20 is fixed to the perimeter of the tray 4 by a series of screws ensuring a seal between the box formed by the tray and its cover, thus preparing a sub-assembly comprising the battery 2 enclosed in its box. The vehicle body 16, manufactured without the passenger compartment floor, has instead of This floor has a large opening with a flat contour 18 that extends over the entire base of this cabin.

[0038] On the vehicle assembly line, the closed box containing the battery 2 is lifted to fit under the body of the vehicle 16, by applying the rim 22 of the cover 20 under the contour of the opening 18, in order to tighten a series of screws 26 distributed on this contour with an intermediate seal making the lower seal of the passenger compartment.

[0039] Body stiffening cross members 24, arranged on top of the cover 20, have ends subsequently fixed to the body 16 to reinforce the floor and support the seats. Alternatively, the stiffening cross members 24 can be fixed beforehand to the vehicle body, the top of the cover 20 forming a plane beneath these cross members.

[0040] Figures 2, 3 and 4 show the battery 2 fixed in the casing, comprising a thermal insulation plate 42 which is disposed between the electrochemical cells 12 and the floor of the passenger compartment 20.

[0041] A fan 32 of air conditioning unit 30, inserted in a duct, draws fresh outside air taken from an awning 50 forming a box located at the bottom of the windshield 56, under the engine hood 58, between the passenger compartment 52 and the engine compartment 54, to heat or cool it through heat exchangers, then send it into the passenger compartment, thus providing air conditioning.

[0042] For normal operation, the fan 32 of the air conditioning unit 30 sends the temperature control air into a central duct 34 located in the center console between the two front seats of the passenger compartment, just above the floor 20, which supplies two lateral ducts 36 passing under each front seat. Each lateral duct 36 opens onto one side of the vehicle through an outlet at its end 38 arranged along the longitudinal direction substantially in the center of the passenger compartment.

[0043] A floor mat 40 is arranged above the entire floor of the passenger compartment 20 forming the cover of the battery box, with an intermediate safety space 46 having a substantially constant thickness E which is held between the two by intermediate wedges.

[0044] Each lateral conduit 36 ​​having a flat section placed on the floor mat 40, opens at least at one place onto a hole 44 substantially in the middle of this mat in order to put it in communication with the intermediate space 46 on this side of the vehicle.

[0045] A controlled flap 48, located between the perforation in the mat 44 and the end outlet of each lateral duct 38, allows, in a rest position during normal operation, the perforation to be closed to connect the air conditioning unit 30 to the outlet The end piece 38, in an activated position, opens this bore by closing off access to the exit. The control of the shutter 48 can include any type of motorization, including in particular an electric motor or an electromagnet.

[0046] Advantageously the intermediate space E has a thickness between 3 and 30mm which ensures both thermal insulation between the floor mat 40 and the floor 20, and the possibility of circulation of an air gap in this space.

[0047] In normal vehicle operation the controlled flaps 48 are at rest by closing the perforations 44 of the floor mat 40, the air conditioning unit 30 sends cooled or warmed air to the feet of the passengers through the end outlets 38 of the side ducts 36.

[0048] In the event of detection by the battery control system of a thermal runaway problem of its cells 12, which begins to strongly heat the passenger compartment floor 20 directly in contact with this battery, this system causes an automatic tilting of the flaps 48 which connect the intermediate space 46 under the floor mat 40 with the air conditioning unit 30, by closing the end outlets of the side ducts 38.

[0049] In addition, the various internal air distribution flaps of the air conditioning unit 30 are operated to connect the outside air intake of the vehicle with the central duct of the passenger compartment 34. The fan 32 is then operated in reverse so as to generate a vacuum in the central duct 34, and through the lateral ducts 36 a suction in the intermediate space 46 under the floor mat 40, at the very source of the toxic fumes which are returned to the outside through the canopy 50 following the arrow ASP.

[0050] This system simultaneously cools the intermediate space 46 by supplying fresh air, replacing the extracted air, thus preventing the floor mat 40 from overheating. It also extracts toxic gases that may begin to be emitted, particularly through the degradation of the floor paint 20, the flexible seals of this floor, or the floor mat. The hot gases, including volatile organic compounds and other toxic components, are expelled from the vehicle, following the reverse path of the normal intake of fresh outside air into the passenger compartment.

[0051] Advantageously, a succession of short suction sequences is ordered by the fan 32, according to a profile determined beforehand by tests, in order not to generate too strong a depression in the intermediate space 46, but sufficient to capture the gases present at the point of their appearance, and prevent their diffusion in the passenger compartment.

[0052] Alternatively, the shutters 48 can have an automatic tilting mechanism, without the aid of a motor, by providing a particular geometry of the axis of rotation by relation to the flap in order to obtain a systematic tilting, against a spring for example, in case of depressurization coming from the air conditioning unit 30.

[0053] Furthermore, during a thermal runaway of the battery of the electric vehicle 2, the rescuers informed of this accident can, with a fire hose 60, spray the base of the windshield 56 to introduce a volume of water into the air intake canopy 50, following the WATER arrow, which passes through the air conditioning unit 30, to then reach the intermediate space 46 under the floor mat 40, passing through the central channel 34 and the lateral channels 36. The ventilation 32 of the air conditioning unit 30 is not necessarily activated, the water descending by gravity into the lower part of the passenger compartment.

[0054] In this way, rescuers spraying a specific part of the vehicle are assured of introducing water to the necessary location to cool the floor of the passenger compartment 20, without hindering the work of operators who are taking care of the passengers remaining inside.

Claims

Demands

1. Electric motor vehicle comprising a box containing a traction battery (2) of this vehicle, which is arranged flat under a floor plate (20) of the vehicle's passenger compartment forming the cover of this box, a floor mat (40) covering the floor plate (20), and comprising an air conditioning unit of the vehicle's passenger compartment (30), characterized in that it comprises an intermediate safety space (46) formed between the floor mat (40) and the floor plate (20), which in the event of significant heating of the traction battery (2) is connected to the air conditioning unit (30) to draw in the volume of air present in this intermediate space (46).

2. Motor vehicle according to claim 1, characterized in that the aspiration of the air volume from the intermediate space (46) uses a fan from the air conditioning unit (32) intended to draw outside air from the passenger compartment.

3. Motor vehicle according to claim 2, characterized in that it comprises two lateral ducts (36) placed on the floor mat (40), which are connected to the air conditioning unit (30) by a central duct (34).

4. Motor vehicle according to claim 3, characterized in that the side ducts (36) have ends (38) which open out along the longitudinal direction of the vehicle substantially in the middle of the passenger compartment.

5. Motor vehicle according to any one of the preceding claims, characterized in that it comprises between the air conditioning unit (30) and the intermediate space (46) movable flaps (48) which, depending on their positions, put the air conditioning unit (30) into communication with the passenger compartment of the vehicle or with this intermediate space (46).

6. Motor vehicle according to claim 5, characterized in that the movable flaps (48) have motorizations which are controlled.

7. Motor vehicle according to claim 5, characterized in that the movable flaps (48) have a geometry comprising a pivot axis which automatically tilts them without motorization to connect the air conditioning unit (30) with the intermediate space (46) when this group (30) generates a depression.

8. Motor vehicle according to any one of the preceding claims, characterized in that the intermediate space (46) has a thickness between 3 and 30mm.

9. A method for securing a motor vehicle according to any one of the preceding claims, characterized in that in the event of overheating of the traction battery (2) it controls a succession of suction sequences by the air conditioning unit (30).

10. A method for securing a motor vehicle according to any one of claims 1 to 8, characterized in that in the event of overheating of the traction battery (2) water is introduced through the outside air inlet (50) of the air conditioning unit (30), while leaving open distribution flaps of this unit to conduct the water towards the intermediate space (46).

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