LU101416B1 - Vehicle rear structure - Google Patents

Abstract

A structure for the rear section of a vehicle is disclosed, together with a method of manufacturing a vehicle with same. The structure comprises an enclosure accessible through a latched body panel of the vehicle. The enclosure includes an inner bottom surface and an outer bottom surface in opposition to each other, wherein the inner bottom surface is optionally for supporting a load therein. A first portion of the outer bottom surface includes a first recess, dimensioned to accommodate a first propellant tank. A second recess may be provided optionally, dimensioned to accommodate at least a portion of a second propellant tank. At least the first portion of the outer bottom surface is located within a boundary defined by one or more peripheral sections of the vehicle chassis and the inner and outer and bottom surfaces jointly define a firewall.

Description

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VEHICLE REAR STRUCTURE A LU101416 \

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X co x : + © N Field of the invention \ © (011 The present invention relates fo 8 sfruclure for the rear section of a vehicle \ ; $ 4 | ; ; oo ; ÿ < More parficuiariy, the présent invention relates io à atructure for accommodating a \ © at al © propetant tank, \ © 3 3 S Background to the invention 7 3 1002} Vehinies which generale a seifpropaliing mothe foros through an internal © © . x x x x xx x x x x x N 1 pombusfion engine ars conventionally squinped with a propellant lank located \ : : © substantially undernesth and generally reanward of the vehicle, À recent fendeney, \ © x : . x . . AA aid ated TN A RS ; $ aided by Improvements in bath pre-programmed vehicle deformation and fire hazard \ © i : $ i 3 i $ 3 ve 3 ¥ ERS) 3 mitigation, has been fo locals the propellant lank directly undemsath the habilat \ © secfion, In order Io best adiust the gravity centre of the vehicle. \ ©

N 3 A an © £ oN gave è i 335, 5 rev ibang Pass = à 1903] Affermarkel techniques based upon aitbmatke propellants have been ; à ; : x x I $ . . x > N developed io help Improve vehicle autonomy and running costs, iypicaliy in cases à : I ng si ct ti fos ae u Pig © nf Ba 8 invoiving aas-fuelled vehicles with relatively poor fuel economy. A wel-known \ à 3 ; : è Tews gd tes N ~ FERRET ws = R aernarket development is based upon the use of liquid pelroteum gas (LPG) as an siternative to regular gas, with a requirement fo reirafit a distingd tank in the vehicle, ; à

N Oa FE 3 STE 3 © tri evi of an frre mad {evel S Hs} Nobwithstanding the promulgation of stringent safely standards for thelr design à and Sting, such affermarket solutions remain highly dangerous lo use, becauta the 7 LES stored in the dedicated tank is both Mighty pressurised and highly fammabie, and ) ; à 28 gush fanks are routinely retrofiitied ai the rear of a vehicle, typically within a reas ) ; à AL i EL 3 x an à i Fey x ; Tamed ae i 3 ad 34e 3 snclosurg, such as the turk of à oar, that is separaied from the vehicle habitat and is pooupants by relatively soft and Rammable partitioning Be rear car ssats or a carpeted à © panel, ;

S an [G8 In parallel to the above, complex exhaust purification Systems have aiso been \ : à sement ; rai A jeux affante of vahin Haiti RGSS Iman | 3 developed fo help miligats the delsterious effects of vehicle exhaust gases upon the à environment, moraover according to ever more restricted levels of exhausted particles ; à i 3 fond € X pri a "pois gies aa ana ÿ deemed harmiui Modern vehicles now routinely include colution-based exhaust ;

N purification systems based upon an aquEous Urea OT ammonia salullon, again requiring 7 a distinct solution tank to be mountad within the vehicle, 3 10081 Accordinoiy, there has been à proliferation of tanks to be mounted in modern \ : y, \ vehicles for à variety of economia and reguiniony reasons, and a corresponding need to \ \ \ $ 3

N PAEQOJELUL draft poland sperification 3

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X ; À : \ $ locate a suitable mounting volume far those, typically within the overall volume of a \ Co NE ; ; Cs ; © ; LU101416 3 veticis body shell ac as to mitigates both environmental wear and Impact fama in case \ | X of accidents. The prior art shows a relatively common approach, rendered conffictuel in \ = i sent 3 ; za Taam x mi Yes ory N view of the sing number of distinct tanks to mount, of repurposing à vehicle's spare \

X : x x x NN 3 “3 N ~ 5 x = 2 AA: N x 8 a wheel well, typicaily localed within and accessible from the trunk of the vehicle, Ic lodge \ y \ ee x vn an : x “> > PAT \ .. N . 2 i 34 > N an affermarket LPG tank (FR2777512, CNSO4INSSES) or & urea or ammonia solution \

X Cs sarpec À tank {JPF20082556808). \ : \ 07) Accordingly thers is à reguirement for an improved structure for the rear section \ ; i ; ; ; Do esfate of Sale à vohisis Sera no Hevzi 3 1 of a vehicle, apt to increase the operational safety of fusliing à vehicle from a Squid 3

X 3 * SEAT IN EN te agi ie « pad aie con ae Big se Fu S petroleum gas tank, without however sacrificing more Useful infernal volume relative to \ { \ kncan solutions,

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S \ KUN \ 15 GOED The present invention mitigates shortoomings associated with the prior art of \ Ini § \ Mn N § re 4: È 3 $ ci ae $ reference by madiiing the conventional configuration of à floor of à vehicle unk, \ > vin \ :

X \ [ml According to an aspect of the present invention therefore, thers is provided a \

PASS X 3 x 7 > ; : ay ne ini oy PN X S structure for the rear section of a vehicle, the structure comprising an anclosurs \ = . x ; Rx x TIQUE Ten Play ae peux Tennis sedans N 3 accessible Hough a latched body panel of the veticis | wherein the enclosure includes \

X ; . . 2 Las nd rebel fine . S inner and outer bation surfaces in opposition to each other | wherein a Ärst portion of \ x : ; ; X s i N N od NM NEN Fon SANS SVE en ey ny Tire N the outer bottom surface inoludes a first recess dimensioned to accommodate a first ; | Co = propallant tank ; wherein a second portion of the outer bottom surface imudes a \

X ; § ; A { € 4 AN x 8 second racass dimensions Io accommodate at least & portion of à second prapeliand \

X 235 tank wherein at least the first portion of the outer bottom surface à bounded by ong c \

X mors peripheral section(s} of a chassis of the vehicle ; and wherein the inner and outer | = rnd a I ÿ and bottom surfaces ininth define a frawai, 7 ÿ Peter ist à x : x . SN nu Tend x PA a aa ; ® [GIG M an embodiment of the structure, the oufer bottom surface substantially | | ; i x i Ir ; & ya RY AN > nieydtirens Le N 305 paras! to the inner bottom surface, and the inner bolton surface is congave relative IQ \

À : + . x Be IY: . N the enclosure, Advantageously, the Inner and outer bottom surfaces can than be we \

X Ç - ue 2 ; & 2 . ao antares ter pre 3 apposed faces of à same fireproof bulkhead, stamped or otherwise detormed to create \ | . ; ; ; X the first recess in à single operation, whilst preserving the material and structural = . : cs x N integrity of the bulkhead, |

N 28 S : 5 3 : $ Am amies = N D011 Embodiments of the structure are particulary weit sulted to accommodate a \ î } 3 iquefied petroleum gas (LPG) tank as the Tred propetiant tank, wherein the second \ = 7 ÿ

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Ÿ A $ + 3 ÿ 3 £003 3 SD ak AA 9 : NN rate nes 3 ; im N gropeliant tank ls 3 gas or diesel tank convenlionally located undernesth the vehicle ) in x ; ; LU101416 ; habitat partly or fully forward of the enclosure. \ à

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X KENT In an embodiment of the structure, the Brat portion of the outer boftom surface ig \ ; . | X S preferabily localed between à reammost of the ons or more peripheral sections) of the Chassis and a rearmest axle of the vehicle, This configuration increases the safely of vehicle sosupsnts In cass of & rear-aspect impact, by repurposing the vehicle rear axie \

N as à physical barner infermediaie the first propellant fank and both the lower portion of \ ; N S the vehicle habitat and the second propefiant tank À present. \

NE S \ MN MY} & : , ms à nee 8 CE ; A dr A à 54 x, be È 3 190131 In another smbadiment of the structure, which may complement the previously $ introduced smhodiment, a depth of the first recess relative to the cular bottom surface, \

X . . : ; x . x LA N may be less than & maximum height of the one or more peripheral chassis sgectior(s) \ = \ fd a. : sisi nd og . Tile se : nd N relative lo à surface on which the vehicle reste or travels, This configuration again \

X 2e : Ala 5 ; wg © i == AM A ipa i 3 S iS increases he safely of vehicle pooupants In case of à rear-aspect Impact, by ensuring \

X that the first recess ts fully surroundsd by the vehicle chassis wharsby, sublect to the \ severity of the impact, the chassis absorbs all or most of Impact forces before they à x transfer io the frat recess and the first propellanı! tank housed therein. à

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S , . SNe 20 ar x Sons 2 _ Ts na 3 3 00141 In an embodiment of the airucture, the frat recess may be shaped as an \ affintical oylinder, ordenled Lansverse io a plans defined by the oder bollom surface. 3 3 : S : os Cs . scsi es re: ; S The first recess may for instance be embodied centrally of the esnclosure’s inner and \ outer bottom surfaces, effectively as arinverted spare whae! weil, This embodiment is \ : ; S 3 i Fon res fi ong aid x a. oz ge Ÿ i * ‘ ; X ~; Sas >. oy à S particulary weil sulted to accommacdaie substantially toroidal fret propetiant tanks. °

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Ÿ (00151 In an aitemative erbodiment of the structs, Ihe first recess may be shaped as \

X a rectangular prism, Oriented parallel io a plane defined by the outer bottom surface. \

X The first recess may for instance be embodied parallel to the rear axie and adjacent an °

N 3 ; n N N PRS J 7 à st FRE 3 E Fils en i 3 lang = N edge of the enclosure, either proximal or distal the adjacent habitat, This embodiment ° 3à & particulary weil sulted to accommodate substantially oylindrical first propellant tanks. \

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X 016] À removable panel adapted lo cover the first recess snd the fist propellant lank \ therein may ussiully be provided for any of the structure embodiments Intoduced \

X herein, in order to faciliiate access for inspection ard maintenance of the fret propellant \

X : à X tank 3

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À 4 3 100171 According fo another aspect of the present invention, there is also provided a \ = N nu [ LU101416 | method of manufacturing à vehicle, comprising steps of providing a floor for a rear \

X . ; x ; x ‘ > $ section of the vehicle, the floor having inner and outer boffom surfaces opposed to \

X ; x 23 : ss Eu ‘ ; NT of à S sach other and made of a material impervigus to fre : shaping a first portion of the 3 ; : a : ; is ie A Ed ÿ < guter bottom surface of the floor with à first recess dimensionad fo sccommodate à first

X ; : ; : © ; oS : Re $ propellant tank ; shaping à second portion of the outer bolton surface with a second ; 3 : : x ins Là : “Fo N or ivse $s + ÿ recess dimensioned io socommodate at least a portion of à second propellant tank : ; 3 $3 3 ied ; £ acd ends enn 44 Fr CN ay} mé Ama R providing a chassis for the vehicle and locating the Hour relate thereto, sc that ai least \

X im $ { £3 : $id dpm ae - "et 8 the first recess is bounded by one or more peripheral section(s) of Ihe chassis | and \

X 3 3 ç # SEE SR ie R 1 securing the first propellant tank in the first recessed porary, \

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X 3 = ; ; ; £ N Sn ng efor be ÿ HIS] fn an embodiment of the structure, wherein the ouler Doom Surnace \ substantially parallel to the Inner botlom surface, the step of shaping may further | © 3 comprise shaping the inner beltom surface to be concave relalive to the anclosurs. \ i Q \ x . x 5 x 3 of aa on sas 8 This embodiment advantageously provides the same benefit of single-operation \ ; S stamping, or othensise deforming, à unitary Freproof bulkhead sc as to create the first \ 3 3 : ; ; Londaneveting ond Sher dna dhe Frye 3 recess whilst prosendng the material and structural integrity of the bulkhead, \ 3 3 3 à x î 3 : mio CEE hed Ry ÿ HNHS] According to a further aspect of the present invention, there is also provided a \ I ) i lei 83 { ; fre HO A nm Pad og = 3 sn vehide comprising an embodiment of the structure introduned herainatowæ, or \ a \ manfactured accerding to an ambodiment of the method introduced hersinabove, An \ ambodimant of the vehicle may thus comprise à Iquefled petraleum gas tank located \ 3 \ 3 eu À dave a N weithin the fret or second recessed portion, \ ès = 3 N Sens + 3 Dee PATS SE ened N 28 (5020) According fo yet another aspect of the present invention, there is ala provided \ ; oe \ a propellant tank for use with embodiments of the structure, or of the method of vehicle \ \ Td it z X nam 8 rmenufacturing, or of the vehicle, all introduced NEreinabuve. \ 3 3 x . © Eee : ; toned Len fire a mari mimi 3 [I Other aspects of the present invention are as stated in the appended claims. \ An 38 > tal 2 3 Brief Description of the Drawings ‘ (0221 The invention will be more dearly underatood from the folowing description of ; an embodiment thereof, given by way of sxample only, with reference io the ; x x x N sooampanying drawings, in wbione ;

N ae ÿ 23 \ = Tad ; 3; X ; . 2 nf yn x av 3 Figure 1 is a perspective view of a vehicle underside, having à rear section structure ; { = x < N according to an embadiment of the invention : ; 8 : 2 Tel IN DON SR 3 Figure 2 is an arthagonal view of the vehicle underside of Figure 1; 3 3 3 PISONIBLU drall patent spacilicalion \ 3 3 3 ÿ

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X à © Figure 3 is à lateral view, partially in section, of the vehicle of Figures 1 and 2, having a es ; a erst LU101416 > rear section structure according to another embodiment of the invention; Figure 4 is a Iateral view, partially in section, of the vehicie of Figures 1 lo à, having a \ Q ; x x; Te cobb ng I $ à 3 mets . S rear section structure according lo à further embodiment of the invention | ) à x © x & + Re severed N 3 Figure § is a perspective cutaway view of the vehicle of Figure 4; and à ; tan ; ; +4 bl Bers ends 3 S Figure 8 is a interval view of yet another embodiment of the rear section struciure, ) à © à © à © : esd ; x Detailed Deserintion of the Drawings ) 19523] There will now be described by way of example à specific mode contemplated by the Inventors, in the following description numerous specific details are set forih in | 3 ; ; ; ; A resend Fnac is nom ok lod i 3 order te provide a thorough understanding. It will be apparent however, lo One skilled in \ © the art, that the present invention may De practiced without imitation fo these specife $ } 7 details. In other instances, well known methods and structures have nol been \

N described in detail so as not io unnecessary pbsoure the description, \ © 3 18 \ © es . À © (00241 À vehicle 10 is shown in Figures 1.16 § wherein ke teferencs numerals | designate Hho fsaivres. in Ihe example, the vehicle Is à personal automobile with a \ 8 \ body shelf of the sedan fype, having @ habitat section 80 located riermeciais @ fram \ > $ section 30 housing an internal combustion engine 32 atop à front axle 34, and a rear \ \ N . ; “ N 36 sechon 40 comprising an enclosure 42 alop a rear axie 44, wherein the enclosure is \ © . . - a : NP UN : 3 anvesainle through a leiched body panel 54 of the vehicle. The enciqaure 42 in this \ . 3 = + LL GA SL ass ; nn Cel S smbodiment defines a rear trunk of the vehicle 1, In which a user may place à Gad für \ \

A transport ,

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[0024] The enclosure 42 extends over substantially the with of the vehicle rear axts \ \ 44 and comprises a floor 50 and peripheral walls 82.5 extending upwards from the \

N ; © U u 3 floor, respectively : one wall 82, rewrmost of the vehicle and another wall 88 \ ; ; | \ intermediate the enclosure volume and the habitat section 20, wherein Loin are 3 substantially parallel to sach other and to the rear axle 44 ; and two walls 8205 parallel } : : onan dls Feng srsrèle TO sina 3 io each other, perpendicular fo the rear axe 44 and interaiy bounding the enclosure ; volume. The enclosure 42 further comprises the latched panel 44, which is substantially ; narallel to the Hoor 50 and conventionally hinged about à top aspect of the wall 85 ; ı \ ys ; x 3 extending between the enclosure volume and the habitat section 20. ; . : x . J N {00261 The Aoor 50 of the enclosure 42 includes an inner bottom surface 50 for 7 > x gecermodating à load which the user may place Iherein for anspor, and an outer \ baton surface 70 opposed to ihe inner hoffom surface BO and facing the ground ; 3 underneath the vehicle 100 In the embodiment shown and described, the inner and \ 3 3 3 3 PESEEELU draft patand speciication 3 3 3 \

S \ \

À 2 3 3 Ce cr owe ; ; . 8 à ; . = oder bolfom surfaces 80, 70 are opposed faces of a unitary sheet, which is preferably \ Co KL . | ; . j LU101416 © made of 3 material subsiantiaiiy impervious to fire, whereby the inner and pulser and : I. N x ÿ bottom surfaces jointly define a frewai 50, \

N \ à X EET In this embodiment, = first portion 72 of the cuter bottom surface 70 includes a \ first recess dimensioned to accommodate a first propellant tank 80, In the example a \ = = x EN ve : : ond font 44 NY did mike ISO S toroidai LRG tank 80. Accordingly, the material of the finor still preferably sxhildis à x . Cs : “es : x ; x : 2 3 ; N siructural characteristics apt fo withstand an involuniary explosion of Ihe LPG tank 80 à x ; ; N . ~ adiacent to the outer bottom surface FU, \

X SAAN OY 4445 “ i; oy raed nnariinn FD nf th Nabe + . pra arden even EY De sabes S 15028] In this embodiment, the first portion 72 of the outer bottom surface 70 is located à

X ; Gi ES y VS ut Lee > à Cian N betwesn the reanmost wall 52, of the endoswrs 42 and the rear ade 44 of the vehicle \

X = © ; ; ; . rn . ; U RN

15. Alternative embodiments are contemplated, wherein the first portion 72 may be \

X « ; 3 is è nee ox tee SEN 3 : ~t Sora or +3 $ ene da 3 3 ÿ locales parfiaily or even fully atop the rear axle 44, in dependence an Ihe design of the \ x x : Es X 5 € + Synge on za en à aes Seal Her min A N 3 vehicle body shell, particularly in the case of hatohback types, typleally having wheel \ x . y ILE N axies located more proximals sach comer of the vehicle, \

S

X RE x x : x ps x i ios x : > N EHR In an embodiment shown in Figure à a removable and/or hinged pane! 78 is \ : provided fo cover the first recess 72 and the first propellant tank 80 therein, in order io \

N Ar Far a teams 4 a A sed ze a prier d > mers genie her FT. X 26 impode he ingress of dust, particles, moisivre and varidus other types of \ anvironmental projection and contaminants in and around the fank 80 The sanet 76 is : ’ S preferably made of the same material substantiaiiy imperviqus to fre as the ficor sheet A

S 59, and ds lsiching andor binging wachaniam{s) are preferably configured Lo \

N withatand, even if only partially, an invoiuntary explosion of the LPG tank 80 within the \

N . x N 28 first recess. \

S S X

N (00301 In an embodiment shown in Figures 4 and 5, a depth D of the first recess 73 | } \ relative to the outer botiom surface 70, is loss than & maximum height of peripheral

X saotions 50 of the vehicle chassis, relative to the ground on which the vehicle 10 rests. \

X

N S \ (00311 With reference to Figure 5, when the vehicle engine 32 may be afternativeiy ° ) N x : set : x i i : > Bg ae cv Bacar - S fused with à gas or diesel propatiant, à second portion 74 of the outer bottom surface |

S ve © 3 3 > = à . Tevet oo > ~ a od av ° + N 70 of the floor 50 of the endosurs 42 Inoiudes a second recess dimsnsionsd © =

X A pvr anton des = oe ener ot ond ey SUR ed . tony TAN Baia dir am amet mnt ran? 3 accommadate af least part of a second propellant tank, typically an end portion thereof, = 38 in the example a rectanquier gas tank 88 as fiustratad In both Figures Sand 5. \

À X

X (00321 The first recess 72 is preferably implemented al the time of manufacturing the \ vehicle 10, by shaping the first portion 72 of the couter bottom surface 70 of the floor 50 \ inte à configuration wherein, regardless of the embodiment, à concave shape is \

N X X X X X

X an ar X PTSOQUELL draft patent specification \

N X X X X N S N \

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X i ; ¥ =, 3 ra] ; y SAN mi im, x 3 4 3 $ Iran ia N imparted to the first recess 72 relative fo the enclosure 48, Le. the first portion Infrudes ies : Lu , LU101416 } within the volume of the enclosure, rather than projecis underneath it \ x 10032) The shaped floor 50 can then be positioned and securen, by welding, sealing or \ & a similar securing technique, relative io one or more rear section(s} 80 of the vehicle \

À chassis, so that the first recess 72 is peripherally bounded by the peripheral sectionts) 3 3 ; : ; e 5 à ; fe OT 2: in on at ; S 0, ns Hustrated in Figure & of the chassis. The first propeliant tant 80 can then be 3 ï | semurad within the first recessed portion 72. \ = , VRAI OT Ier 8 Imre | mhewtiad Ihn cui S 100341 The shaping operation may for Insiance be embodied through pressing, 3 i 3 | ws ati x < . it Ent t paid one on $id std Nr S punching or à similar metabforming technique, the material pale constiiuting the foor \ ’ a of the enclosure 42, prior io mounting same within the vehicle chassis, Given the

S $ x < pa à as Etes , im 3x 3 Ps S apacific example of the foroidal LPG tank 80, the first recess 72 is given the shape of 3

S an slliptical oyfinder, crianted subsiantaily Tansverse fo à plane defined by the outer \

S nat heed ; sx far Bh Fret rennes S 33 botlony surface 70 The skilled person may consider ofher shapes for the fest recess 3 3 ; ¥ A 3 x = >, 3 end on dy res Fan an $Y pT = S 73, according to other hpes andlor shapes of propellant lanks, for example a \ rectanquisr orism orented paratfel to the plane defined by the outer bottom surface 746, | for sccommodating a oyfindricat tank 20 as Hustraied in Figure 6. |

S

N 3 [0033] Reverting to the possibifity of fuelling the vehicle angine 32 with à gas or diese! , propellant requiring a respective second tank 82, and thus the implementation of a | cree 75 ; + S second recess T4 in the outer bottom surface FÜ, then this second recess 74 may be ° imolemented Hkewise at the me of manufacturing the vehicle 10, by shaping the \ = bos: x “en © A A 3 - Aa zx S second sorfion T4 of the outer bottom surface 70 of the floor 50 compementarfiy with

X 33 the shape of the second fuel tank or an end portion theveol proximate the rear section | | = se : x . ~ N 40, as Hustrated in Figure 5. \

X S N

X ; x 5 : : x LE ; ces Bae Shen cen N {90351 Accordingly, the invention disclosed herein provides a structure for the ren: \ | 2 ; 344 y fon Abe salam y avants LA ee N section of a vehicle, together with a method of manufacturing 8 venicie with Same, \

S a © ; ; NT en meds nf $self m it S 38 embodiments of which all generally Increase the operational safety of fuelling a vehicle | 3} a x x a + ON a > ; N from Hopad petroleur gas tank. \

N \

S \ aation i : ; SRS à Saad and or TA S (00371 In the specification the farme “comprise, comprises, comprised and comprisiig 7 è i : | tout y x Bee Zelda Innliidad a ; retirant eng reste S or any variation thereof and the terme include, includes, included and including” or any \ x if 3 3 A $ = 33 45 \ ax € Le x nn N 3x variation theres! are considered to be totally interchangeables and they should all be afforded the widest possible interpretation and vice versa, The invention is not limited = to the embodiments hereinbefore described but may he varied in both sonstruntion and

N datad.

S , x ÿ x 3

N \ PTSCHISR Li dirait patent speaiiicadion , 3 3 3 3 x

Claims (13)

Claims LU101416

1. A structure for the rear section of a vehicle, comprising a chassis having a plurality of peripheral sections and an enclosure accessible through a latched body panel of the vehicle, wherein the enclosure includes inner and outer bottom surfaces in opposition to each other and jointly defining a firewall ; and wherein first and second portions of the outer bottom surface respectively include first and second recesses, with each recess dimensioned to accommodate a respective propellant tank ; characterised in that at least the first portion is bounded by one or more of the peripheral section(s) and located between a rearmost of the one or more peripheral section(s) of the chassis and a rearmost axle of the vehicle ; and a depth of the first recess relative to the outer bottom surface is less than a maximum height of the one or more bounding peripheral section(s) relative to a surface on which the vehicle rests or travels.

2. A structure according to claim 1, wherein the outer bottom surface is substantially parallel to the inner bottom surface, and wherein the inner bottom surface is concave relative to the enclosure.

3. A structure according to claim 1 or 2, wherein the first propellant tank is a liquefied petroleum gas (‘LPG’) tank.

4. A structure according to any of claim 1 to 3, wherein the first recess is shaped as an elliptical cylinder, oriented transverse to a plane defined by the outer bottom surface.

5. A structure according to claim 4, wherein the first propellant tank is substantially toroidal.

6. A structure according to any of claim 1 to 3, wherein the first recess is shaped as a rectangular prism, oriented parallel to a plane defined by the outer bottom surface.

7. A structure according to claim 6, wherein the first propellant tank is substantially cylindrical. P150936LU.02

8. A structure according to any of claim 1 to 7, further comprising a removable panel adapted to cover the first recess and the first propellant tank therein.

9. A method of manufacturing a vehicle, comprising steps of providing a chassis for the vehicle, the chassis having one or more peripheral section(s) ; providing a floor for a rear section of the vehicle, the floor having inner and outer bottom surfaces opposed to each other and made of a material impervious to fire; shaping first and second portions of the outer bottom surface respectively with first and second recesses, with each recess dimensioned to accommodate a respective propellant tank ; locating the floor relative to the chassis, so that at least the first recess is bounded by one or more of the peripheral section(s), located between a rearmost of the one or more peripheral chassis section(s) and a rearmost axle of the vehicle, and less than a maximum height of the bounding peripheral chassis section(s) relative to a surface on which the vehicle rests or travels ; and securing the first propellant tank in the first recess.

10. A method according to claim 9, wherein the outer bottom surface is substantially parallel to the inner bottom surface and wherein the step of shaping further comprises shaping the inner bottom surface to be concave relative to the enclosure.

11. A vehicle comprising a structure according to any of claims 1 to 8, or manufactured according to the method of claim 9 or 10.

12. A vehicle according to claim 11, comprising a liquefied petroleum gas tank located within the first or the second recessed portion.

13. A propellant tank for use with the structure according to any of claims 1 to 8, or with the method of claim 9 or 10, or with the vehicle according to claim 11 or 12. P150936LU.02