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

Abstract

Electric motor vehicle comprising a box containing a traction battery of this vehicle, which is arranged flat under a floor sheet (20) of the passenger compartment of the vehicle forming the cover of this box, a floor mat covering the floor sheet (20), an air conditioning unit for the passenger compartment of the vehicle (30), and comprising an intermediate safety space formed between the floor mat and the floor sheet (20), which in the event of significant heating of the traction battery is connected to the air conditioning unit (30) to suck 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 BATTERY BOX COVER

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

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

[0003] The batteries are arranged in a rigid closed box which provides mechanical protection for the internal components to protect and withstand the various possible impacts on the vehicle during accidents. The box generally comprises a flat lower tray forming the underside of the vehicle, containing a tray receiving a cooling fluid, a frame having housings receiving 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 polluting elements 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 lower face of the box tray forming the underside of the vehicle meets a minimum distance requirement from the ground in order to allow driving on different terrains. The aim is to limit the total thickness between the lower face of the tray and the floor of the passenger compartment, including the battery, to keep the floor sufficiently low while preserving a maximum available volume in order to accommodate a battery with the greatest charge capacity.

[0006] According to a known embodiment, an independent box is formed receiving the battery and closed by its watertight cover, which is fixed under the floor of the passenger compartment including its stiffening crosspieces, while 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 sheets of the floor and the cover, and the intermediate air gap, is relatively large. In addition the floor and the cover form two superimposed sheets which add mass to the vehicle.

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

[0009] As a variant, the cover of the battery box may include the crosspieces for stiffening the floor, the bottom of the passenger compartment having a large opening which then receives the box fixed around this opening to form at the same time the floor of the vehicle 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 cover of the box, avoiding the superposition of two sheets which reduces the mass, and gives a minimum thickness between the floor and the underside of the vehicle.

[0011] Generally speaking, battery boxes include an internal cooling system for evacuating the calories generated by the normal operation of this battery.

[0012] Furthermore, a known type of electric vehicle, presented in particular by document US-A1-2004062955, comprises two successive compartments arranged flat under the floor of the passenger compartment, comprising at the front a fuel cell, then after a vertical partition equipped with thermal insulation a battery powering an electric traction machine of the vehicle. The rear floor comprises air inlet holes above the battery compartment, and air outlet holes equipped with a fan allowing the air contained in the passenger compartment to circulate inside this compartment to cool the battery, then return 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 the comfort of the passengers, 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 thermal runaway of electrochemical cells, very hot gases delivering a significant quantity of thermal energy are produced in the box, strongly heating the floor.

[0015] The passenger compartment floor of vehicles generally receives a carpet forming a floor mat ensuring comfort by thermal insulation and soundproofing, and supports various equipment which is fixed on it. Significant heating of the floor sheet metal, in particular with a temperature reaching 150°, causes serious problems, in particular vaporization of the paint of the floor, its joints and the organic components of the floor mat, thereby releasing toxic gases which are harmful to the passengers.

[0016] Particularly after a vehicle collision, toxic gases can inconvenience passengers remaining confined in the passenger compartment, causing a reduction in their alertness 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 of this vehicle, which is arranged flat under a floor sheet of the passenger compartment of the vehicle forming the cover of this box, a floor mat covering the floor sheet, and comprising an air conditioning unit for the passenger compartment of the vehicle, this vehicle being remarkable in that it comprises an intermediate safety space formed between the floor mat and the floor sheet, which in the event of significant heating of the traction battery is connected to the air conditioning unit to suck in the volume of air present in this intermediate space.

[0019] An advantage of this motor vehicle is that in critical occasions including a strong rise in temperature of the floor sheet metal, during thermal runaway of the battery, by suction of air into the intermediate safety space, this space is cooled by the supply of fresh air which makes it possible to delay the heating of the floor mat placed above and of materials such as the paint and the floor joints, and any toxic gases which could begin to appear due to decomposition of nearby components are sucked out.

[0020] This provides a delay before significant heating of the floor mat and other materials giving rise to critical temperatures which release toxic gases, ensuring protection for the passengers during this period, enabling 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 suction of the air volume from the intermediate space uses a fan of the air conditioning unit designed to draw outside air from the passenger compartment.

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

[0024] Furthermore, advantageously the lateral conduits have ends which open in the longitudinal direction of the vehicle substantially in the middle of the passenger compartment.

[0025] Advantageously, the vehicle comprises between the air conditioning unit and the intermediate space movable flaps which, depending on their positions, put the air conditioning unit in communication with the passenger compartment of the vehicle or with this intermediate space.

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

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

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

[0029] The invention also relates to a method for securing a motor vehicle comprising any one 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 one of the preceding characteristics, remarkable in that in the event of heating of the traction battery resulting from a failure, water is introduced through the outside air inlet of the air conditioning unit, while leaving open the distribution flaps of this unit to conduct the water towards the intermediate space.

[0031] The invention will be better understood and other characteristics and advantages will appear more clearly on reading the description below given by way of example, with reference to the appended drawings in which:

[0032] [Fig-1] is a vertical 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 sectional view along a vertical plane of the floor of this vehicle with the battery underneath; and

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

[0036] [Fig.l] shows a battery 2 fixed in a tray 4 made of a resistant sheet metal, comprising successively starting from the bottom a lower flat sheet metal of the tray 6, a battery cooling plate 8 comprising 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 contour of the tray 4 by a series of screws ensuring a seal of the box formed by the tray with its cover, which makes it possible to prepare a subassembly comprising the battery 2 enclosed in its box. The body of the vehicle 16 manufactured without the floor of the passenger compartment, has instead of this floor a large opening with a flat contour 18 which extends over the entire base of this cabin.

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

[0039] Body stiffening crosspieces 24 arranged on top of the cover 20 have ends then fixed to the body 16 to reinforce the floor and receive the seats. Alternatively, the stiffening crosspieces 24 can be fixed beforehand to the body of the vehicle, the top of the cover 20 forming a plane coming under these crosspieces.

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

[0041] A fan 32 of the air conditioning unit 30, inserted in a duct, draws fresh outside air taken from a cowl 50 forming a box arranged 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, providing air conditioning.

[0042] For normal operation, the fan 32 of the air conditioning unit 30 sends the temperature-regulating air into a central duct 34 placed on the floor located in the console between the two front seats of the passenger compartment, just above the floor 20, which feeds two lateral ducts 36 passing under each front seat. Each lateral duct 36 opens onto one side of the vehicle via an outlet at its end 38 arranged in 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 maintained between the two by intermediate wedges.

[0044] Each lateral conduit 36 having a flat section placed on the floor mat 40, opens at least in 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 arranged between the bore of the belt 44 and the end outlet of each lateral duct 38, allows in a rest position during normal operation to close this bore to connect the air conditioning unit 30 to the outlet end 38, and in an activated position opens this hole by closing access to the outlet. 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 of between 3 and 30 mm which ensures both thermal insulation between the floor mat 40 and the floor 20, and the possibility of circulation of an air blade in this space.

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

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

[0049] In addition, the various internal air distribution flaps of the air conditioning unit 30 are operated to connect the exterior 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 depression in the central duct 34, and by 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 sent back to the outside by passing through the awning 50 according to the arrow ASP.

[0050] Both cooling of the intermediate space 46 is obtained by the supply of fresh air replacing that sucked in, which prevents heating of the floor mat 40, and suction of toxic gases which may begin to be emitted, in particular by degradation of the paint of the floor 20, the flexible sealing joints of this floor, or the floor mat. The hot gases comprising volatile organic compounds and other toxic components are evacuated to the outside of the vehicle, taking the opposite path to the normal entry of fresh outside air into the passenger compartment.

[0051] Advantageously, a succession of short suction sequences is controlled 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 place where they appear, and avoid their diffusion into the passenger compartment.

[0052] As a variant, the shutters 48 can have an automatic tilt, without the aid of a motor, by providing a particular geometry of the axis of rotation by in relation to the shutter in order to obtain a systematic tilting, against a spring for example, in the event of depression coming from the air conditioning group 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 awning 50, following the arrow WATER, 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, the rescuers watering a specific part of the vehicle are assured of introducing the water to the place necessary 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

Claims

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

2. Motor vehicle according to claim 1, characterized in that the suction of the air volume from the intermediate space (46) uses a fan of the air conditioning unit (32) provided 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 lateral conduits (36) have ends (38) which open in 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) in 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 shutters (48) comprise motors 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 tilts them automatically 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 of between 3 and 30 mm.

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

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

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