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

Abstract

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, and comprising a floor mat (40) covering the floor sheet (20), this vehicle comprising at least one duct (58) connected to an external air inlet, which opens directly into an intermediate safety space (46) formed between the floor mat (40) and the floor sheet (20). Figure 3

Description

Title of the invention: MOTOR VEHICLE WITH AIR INTAKE 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] For this purpose, 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, and comprising a floor mat covering the floor sheet, this vehicle being remarkable in that it comprises at least one conduit connected to an external air inlet, which opens directly into an intermediate safety space formed between the floor mat and the floor sheet.

[0019] An advantage of this motor vehicle is that in critical occasions including a high temperature rise of the floor sheet metal, during thermal runaway of the battery, by creating a depression on one side of the intermediate safety space, an introduction of a flow of fresh air from the duct which directly takes outside air through its air inlet is obtained from another side of this space.

[0020] The flow of fresh air in the intermediate safety space provides both cooling of this space which makes it possible to delay heating of the floor mat placed above and of materials such as paint and floor joints, and replacement of possible toxic gases which could begin to appear by decomposition of nearby components.

[0021] 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.

[0022] The motor vehicle according to the invention may further comprise one or more of the following characteristics, which may be combined with each other.

[0023] Advantageously, the vehicle comprises an air conditioning unit fan carrying out suction of the volume of air from the intermediate safety space which is renewed by outside air coming from the inlet ducts.

[0024] According to one embodiment, the vehicle comprises exterior air inlet ducts which constitute water evacuation ducts around a sunroof of the vehicle.

[0025] In this case, advantageously the outside air inlet ducts comprise three-way valves allowing communication between the outside air inlets and outlets under the vehicle for evacuating rainwater, and to interior outlets opening into the intermediate safety space.

[0026] In particular, the three-way valves may include air direction flaps which tilt automatically when there is a depression in the intermediate safety space.

[0027] According to another embodiment, the vehicle comprises an inlet duct opening into a housing of a roof antenna forming an exterior air inlet.

[0028] In this case, advantageously the antenna housing is connected to the body of the vehicle by a seal allowing air to enter without allowing external water to enter.

[0029] The invention also relates to a method for making a motor vehicle safe, comprising any one of the preceding characteristics, remarkable in that in the event of heating of the traction battery resulting from a failure, it controls a depression in the intermediate space causing external air to enter it through the inlet ducts.

[0030] The invention further relates to a method for operating a motor vehicle comprising any one of the preceding characteristics, remarkable in that during normal operation of the traction battery releasing heat energy, it generates a suction of air coming from the outside passing through the inlet ducts to heat this air by circulation in the intermediate space, then distribute it in the passenger compartment.

[0031] The invention further relates to a method of operating a motor vehicle comprising any one of the preceding characteristics, remarkable in that during normal operation of the traction battery it generates a suction of air coming from the outside passing through the inlet ducts to ventilate the intermediate space by removing humidity.

[0032] 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:

[0033] [Fig.l] is a vertical sectional diagram along the longitudinal axis of an electric vehicle according to the invention comprising a battery box cover forming the floor of the passenger compartment;

[0034] [Fig.2] is a top view of the floor of this vehicle;

[0035] [Fig.3] is a sectional view along a vertical plane of the floor of this vehicle with the battery underneath;

[0036] [Fig.4] shows an overall view of this vehicle and a detailed view of its entrance outside air through the sunroof; and

[0037] [Fig.5] alternatively presents an air intake via a vehicle roof antenna.

[0038] [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 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.

[0039] 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 in place of this floor a large opening with a flat contour 18 which extends over the entire base of this passenger compartment.

[0040] 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.

[0041] 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.

[0042] Figures 2 and 3 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.

[0043] A fan 32 of the air conditioning unit 30, inserted in a duct, draws fresh outside air taken from a canopy forming a box arranged at the bottom of the windshield, under the engine hood, between the passenger compartment and the engine compartment, to heat or cool it through heat exchangers, then send it into the passenger compartment, providing air conditioning.

[0044] For normal operation, the fan 32 of the air conditioning unit 30 sends the temperature control air into a central duct placed on the ground 34 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.

[0045] 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.

[0046] 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.

[0047] 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 end outlet 38, and in an activation position opens this bore by closing access to the outlet. The control of the flap 48 can comprise any type of motorization, including in particular an electric motor or an electromagnet.

[0048] Advantageously, the intermediate space E has a thickness of between 10 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.

[0049] In normal operation of the vehicle, the controlled flaps 48 are at rest, 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.

[0050] 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.

[0051] 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 via 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 via the awning.

[0052] 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.

[0053] 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.

[0054] As a variant, the shutters 48 may have automatic tilting, without the aid of a motor, by providing a particular geometry of the axis of rotation relative to the shutter in order to obtain systematic tilting, against a spring for example, in the event of depression coming from the air conditioning unit 30.

[0055] [Fig.4] shows an opening roof comprising an interior sheet 50 fixed under the roof sheet 66 of the vehicle body 16, and rails 52 placed on it receiving the sliding roof 54.

[0056] The inner sheet 50 comprises a gutter 56 going around the opening, comprising on each side of the vehicle a hole for evacuating the rainwater received by this gutter, which is extended by a descending evacuation conduit providing an air inlet 58, housed in the interior trim of the passenger compartment to open out through an outlet under the vehicle 60 allowing this water to flow towards the outside under normal conditions of use.

[0057] The conduit 58 comprises a three-way valve 62 which, in a rest position, connects this conduit to the outlet under the vehicle 60, and in an activated position connects it to an interior outlet 64 opening onto the sides of the intermediate safety space 46, as shown [Fig.3].

[0058] 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, this system automatically causes a switching of the three-way valves 62 to connect the evacuation conduits 58 with the interior outlet 64, and controls by the air conditioning unit 30 a suction of the gases from this intermediate space 46 through the holes 44 in a central part of the floor mat 40.

[0059] By depressurizing the central part of the intermediate space 46, an air inlet is obtained from the interior outlets 64 directly connected by the air inlet ducts 58 carrying the outside air taken from above the vehicle. It will be noted that in the event of a fire in the traction battery 2 arranged under the vehicle, the outside air taken from above the roof has every chance of being less mixed with the fumes from this combustion.

[0060] Advantageously, the evacuation conduit 58 on each side of the vehicle is connected with its three-way valve 62 and its internal outlet 64 to the intermediate space 46. arranged on the same side of the vehicle so as to ensure a symmetrical supply of fresh outside air to the sides.

[0061] As a variant, the three-way valves 62 may include automatic control without motorization, comprising flaps which tilt in the event of depression of the intermediate space 46.

[0062] [Fig. 5] shows a roof antenna cover 70 fixed by means of a seal 72 and a base 74 on the roof sheet 66 of the vehicle body. The base 74 has a lower bore comprising a nozzle 76 passing through the roof sheet 66, which receives an air inlet duct 58 comprising at its end an internal outlet 64 arriving on the sides of the intermediate space 46 under the floor mat 40.

[0063] The seal 72 having a porosity allowing the entry of air into the antenna cover 70, but preventing the entry of water, constitutes an external air intake to direct it directly towards the intermediate ventilation space 46 under the floor mat 40, which is also taken from the vehicle far from the fumes resulting from combustion of the traction battery 2.

[0064] In addition, with the seal 72 allowing air to enter the cover 70, the roof antenna contained inside, releasing heat during its operation, is more easily ventilated and cooled.

[0065] In a variant not shown, the exterior air intake of the conduits 58 can be arranged in any other upper zone of the vehicle, such as a rear trunk flap hinge, or a connection with an upper rear spoiler of the vehicle body.

[0066] Generally speaking, during normal operation of the battery 2 its electrochemical cells 12 release calories, giving this battery a temperature of approximately 30°C.

[0067] According to another mode of operation of the invention, the air conditioning unit 30 is used to generate a suction of air coming from the outside via the air inlet ducts 58, which then circulate in the intermediate space 46 slightly heated by the battery 2 arranged under the floor plate 20, before distributing this hot air into the passenger compartment to ensure its heating.

[0068] According to another mode of operation of the invention, the air conditioning unit 30 is used to produce a circulation of air coming from the outside air inlet ducts 58, in the intermediate space 46 in order to dry this space by removing humidity and avoiding the formation of condensation on cold parts. In particular, the presence of a cooling plate 8 in the battery 2 can give a dew point bringing condensation above the passenger compartment floor sheet 20, this humidity is eliminated.

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, and comprising a floor mat (40) covering the floor sheet (20), characterized in that it comprises at least one conduit (58) connected to an external air inlet, which opens directly into an intermediate safety space (46) formed between the floor mat (40) and the floor sheet (20).

2. Motor vehicle according to claim 1, characterized in that it comprises a fan (32) of the air conditioning unit (30) carrying out a suction of the volume of air from the intermediate safety space (46) which is renewed by outside air coming from the inlet ducts (58).

3. Motor vehicle according to claim 1 or 2, characterized in that it comprises exterior air inlet ducts (58) which constitute water evacuation ducts around a sunroof of the vehicle.

4. Motor vehicle according to claim 3, characterized in that the exterior air inlet ducts (58) comprise three-way valves (62) allowing communication between exterior air inlets and outlets under the vehicle (60) for evacuating rainwater and to interior outlets (64) opening into the intermediate safety space (46).

5. Motor vehicle according to claim 4, characterized in that the three-way valves (62) comprise air direction flaps which tilt automatically when there is a depression in the intermediate safety space (46).

6. Motor vehicle according to any one of the preceding claims, characterized in that it comprises an inlet duct (58) opening into a housing of a roof antenna (70) forming an exterior air inlet.

7. Motor vehicle according to claim 6, characterized in that the antenna housing (70) is connected to the body of the vehicle by a seal (72) allowing air to enter without allowing external water to enter.

8. Method for securing a motor vehicle according to any one of the preceding claims, characterized in that in the event of heating of the traction battery (2) resulting from a fault, it controls a depression in the intermediate space (46) causing external air to enter it through the inlet ducts (58).

9. Method of operating a motor vehicle according to any one of claims 1 to 7, characterized in that during normal operation of the traction battery (2) releasing heat energy, it generates a suction of air coming from the outside passing through the inlet ducts (58) to heat this air by circulation in the intermediate space (46), then distribute it in the passenger compartment.

10. Method of operating a motor vehicle according to any one of claims 1 to 7, characterized in that during normal operation of the traction battery (2) it generates a suction of air coming from the outside passing through the inlet ducts (58) to ventilate the intermediate space (46) by removing humidity.

Images