FIELD OF INVENTION
This invention relates to novel underbody structure of vehicle to resist vehicle
cabin deformation in head on collision.
PRIOR ART
The currently available compact passenger vehicles have very less deformable
zone in the front for absorbing the impact energy during collision due to the
compact layout. In case of accident particularly in head on collision, large
deformation of vehicle body has been observed. Also, the same is confirmed in
CAE as well as physical test. Thus, the conventional underbody structure of
vehicle is unable to sustain the impact load during the collision.
During the head on collision, the longitudinal structural member mounted
under the dash and floor is not able to effectively transfer the impact load past
the foot-well area.
Actually, the section under the joinery of the dash panel and main floor is
weak, which leads to large deformation of the entire cabin. Further, rupture of
Spotwelds has also been noticed under floor area due to large impact load
during collision which further deteriorates the foot well area deformation i.e.
crash performance of the vehicle.
Further drawbacks associated with the above are that, door can't be opened
after the collision together with severe leg injury to the occupant and difficulty
in occupant evacuation after collision.
Now, reference may be made to fig. 1, wherein the under body structure
comprising of a floor (F) provided between front and rear wheels. Two
longitudinal members (1 and 2) are provided under the floor spot welded to
.
cat- other at a point (5). The dash lower (D) is provided in connection with said
foor at a point (3). The first longitudinal mernbcr (1) is connected to both floor
'>Cd - ,A;i.., dash lower, in which thc member is spot welded with front longit-t~dinal
T. i.: <..'T T> i > ( ' ~ .._..d;zl I,,; of vehicle a? a point (4). The secorid rrierriber (2) is also spot welded to
iL & <~X ~ . ~ , ,,,:. ;~;~)jirg ). Further, there is sharp change in cross section of the mernbcr (1)
i1-1 proximity to the joining point (3) in transverse direction, which allows
dcf~z-mation from said point (3) in case of hcad on collision. Thcrc is also
7r r r \ r
. . ,,i.,~is~oonf beads in longitudinal direction in members (1, 2).
7 i y ; : ; ~ . -rcfc.r yr~-n- -. -. .. . ),,,, .ilay bc made to fig. :! indicating spot. ;;r::ia ; i ~ p t u, r(2~.i c.:4: z. :-. : -. *:r:t' >*
deforr:iatiori at dash and main floor joint (3) shown by high plastic strains (4).
". i a c.rcl , spot weld rupture can't be avoided even if by increasing spot weld density
and a t ~ d i ~::f~ ;pnat ch.
p:,:
i nt: sh::rt c::mings of the prior art can be summarized hcrcin below:-
During head on collision, the longitudinal structural member mounted
undcr t-c floor and dash is not able to effectively transfer the impact
i:T- . . inc j::lr:e,ry of main floor panel and dash pariel is weak which further
contributes to high foot-well intrusion and front door deformation.
Kupture of spot welds at the location where under floor longitudinal
I mcmbcr connccts with front longitudinal member duc to high amoxnt of
- - . . - i mpac:. load, which further deteriorates the fmt-wci: intrusion arlrl i r::z t
door dehrrnation.
I Large amount of foot-well area deformation results in the serious injury
I t.o !.he t:c:cupant's leg and also makes the t;ccupant cvac~lation
. . .- * i-qgossiblc.
I -. -. . .
+;+. , znz , ,l: ,?, PP c2b;i;l structure of thc compact car should be stiff so as to sustain the
I
-
Now, reference may be made to the following prior arts:-
A known art discloses an automobile floor longitudinal beam and an
automobile having the same. The automobile floor longitudinal beam comprises
a longitudinal beam body. A reinforcing board connected with an automobile
floor is arranged at the front end of the longitudinal beam body. The
automobile comprises the automobile floor, a left longitudinal beam and a right
longitudinal beam, wherein the left longitudinal beam and the right
longitudinal beam are arranged at the front end of the automobile floor, a left
reinforcing board and a right reinforcing board are arranged at the front ends
of the left longitudinal beam and the right longitudinal beam respectively, the
left longitudinal beam is connected with the automobile floor through the left
reinforcing board, and the right longitudinal beam is connected with the
autcmobile floor through the right reinforcing board.
It comprises additional component to reinforce connection strength by only
spot weld. However, the spots may fail during collision due to large impact
load. Further, additional component adds to weight and cost of vehicle with
increase in the assembly time.
CN202765094U:- The utility model provides a vehicle frame which comprises a
front vehicle frame and a rear vehicle frame, wherein the front vehicle frame is
in a trapezoidal structure and comprises two front longitudinal beams arranged
on two sides of the front vehicle frame. The rear vehicle frame is in a boxshaped
structure and comprises two rear longitudinal beams arranged on two
sides of the rear vehicle frame, and the two front longitudinal beams are f~edly
connected with the two rear longitudinal beams. The vehicle frame adopts a
composite structure with a trapezoidal front section and a box-shaped rear
section, wherein sections of the front longitudinal beams are changed from
groove-shaped (or I-shaped) sections to rectangular sections in a transition
mode.
Here, reinforcement is provided in the area, cross-section of which is becoming
smaller. However, it does not fulfill requirements of the proposed application.
Another prior art comprises a vehicle body floor structure for an automobile,
which includes a joint line extending in a vehicle width direction and
connecting a rear edge of a dashboard lower panel and a front edge of a front
floor panel. A side sill extending in a front-rear direction and connected to an
outer edge in the vehicle width direction of each of the dashboard lower panel
and the front floor panel. A floor frame member extending in the front-rear
direction and connected to the dashboard lower panel and an upper surface of
the front floor panel on a side inward of the side sill in the vehicle width
direction, and a floor gusset extending in the vehicle width direction,
connecting the side sill and the floor frame member and disposed on the upper
surface of the front floor panel along the joint line.
In this, increased stiffness is achieved by extending the floor reinforcement
onto the dash panel, connection between which is established by means of
adhesive. However, the efficiency of increase in stiffness is very low due to
presence of the adhesive as it can't be spot-welded.
KR 100501382Bl:- A lower body of a vehicle comprises a front side member; a
front side rear upper member installed longitudinally and overlapped partially
on the front side member. A front side outer rear extension panel overlapped
along the outer circumference of the front side rear upper member and a front
side rear lower member overlapped on the inner periphery of the front side rear
upper member. A dash lower member composed of a side reinforcing member
integrally arranged in parallel with the front side rear upper member, and
overlapped with the front side rear lower member. A dash panel and a center
floor panel installed from the front side outer rear extension panel to the dash
lower member to form the interior space; and a rear upper member
reinforcement installed between the front side rear upper member and the dash
pancl to form the double box.
Thus in this art, a rear upper member reinforcement is installed between the
front side rear upper member and the dash panel to form the double box
section. Also side reinforcing member is integrally provided in parallel with the
front side rear upper member in order to increase the rigidity and minimize
deformation of the dash lower member during front collision.
However, it includes more number of parts due to presence of reinforcements
as well as a new structural member. Hence, it is heavier in weight thus
undesirable for fuel economy of vehicle, time consuming during assembly and
expcnsive.
Further, the sheet metal parts are joined by spot weld only with no permanent
method of joining like arc weld, bolt or rivet. Spot weld is prone to rupture
during the collision due to high amount of impact load which subsequently
increases the deformation level of cabin area.
Hence, the present invention has been proposed so as to address the aforesaid
shortcomings.
BB3ECTS OF THE IBVENTION
Primary object of the present invention is to provide novel underbody structure
of vehicle to resist vehicle cabin deformation in head on collision which
overcomes disadvantages associated with the prior art.
Another object of the present invention is to provide novel underbody structure
of vehicle to resist vehicle cabin deformation in head on collision which is
efficient and reliable.
Still another object of the present invention is to provide novel underbody
structure of vehicle to resist vehicle cabin deformation in head on collision
which is simple in construction.
Further object of the present invention is to provide novel underbody structure
of vchicle to resist vehicle cabin deformation in head on collision which reduces
front door deformation and dash intrusion.
SUMMARY OF THE INVENTION
According to this invention, there is provided novel underbody structure of
vehicle to resist vehicle cabin deformation in head on collision comprising of a
floor between front and rear wheels provided with atleast two longitudinal
members thereunder spot welded to each other wherein first longitudinal
member is spot welded to front longitudinal member of vehicle in which
reinforcement is provided on and under the floor together with a means for
reinforcing connection strength.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Further objects and advantages of this invention will be more apparent from
the ensuing description when read in conjunction with the accompanying
drawings and wherein:
Fig. 1 shows: conventional underbody structure.
Fig. 2 shows: location of rupture, deformation and high plastic strains in
known underbody structure.
57; .- -
. .. ..>,i. - i 4 shows: cbscrvation regarding rupture, deformation a:nd plastic strain in
;;r::s::nt invention.
I . : g . .. a:iows: load path during the frontal crash. c. n+-.
1:.. .7...::.F ..- > . G shows: c:?imparison of plastic strain a ~ fdi-iz gc icvc,'.c., .
F7-7
:: :;..< ,, ,;:<:sent: invcnticn is directed to novel underbody strl.icture of vchiclc to
- . - - . - . - - - . . i.csik: ychiclc cab;n dcrormation in :ricad on c.:;[iis!ofi.
I Wow, rcfcrcncc may be made to fig. 3, wherein the undcr body structure
. .
i:.::::r;::::.ising cf a floor (F) provided between front and rear wheels. Two
i.c;rig;eiidi:ial niernt-;ers (1 arid 2) are provided =rider If-I;: noor spot Weided t<;
........-..- . :-: ..-::+?.<,?- < > < *> ~.<);qi ;q\ 5-b
--,%.-A; ....Lzz.,A GL 52 &,, LA ,uj. i,ie dash lower {f EI;-is. !pr::> vidcd in c:lnnection wit.h said
.- i:i;,:,.,q,r, , ,,;.. - a point j3).-The first longitudinal member (1) is ccnnected to both floor
,, ".: .-. 7 <:r ash lowcr, in which the member is spot welded with front longitudinal
............ ......A.,...........>., ....-.. ...:/ .iI. 2. .: .7 '. . 24 <\:
, 7 - -D. ,I vehicle at a point (4).
1.:.: . ;.:;:; ;;rcs::nt ifivcntion, sharp change in cross scctio:: of the longitudinal
TF:<>T?;::{lT [ 7 1 . ..... z-AAAL.- A ,,; i:i tra~isversed irection (Trarisvers:: t:, the dirt.ctiorl of ir;;pacl load;I
: s < it.; av:r:l-tied. ilowever, anti bending beads in members {!,2) are provided in
i. ;*. j;.-i p ..-- i.. i- .. - L -: f.i- .. I .? ? - : - -. , dlrcctior, ( in line with directior, of impact load) so as to p~cvidc
;--.. i,-r ,r::--i?. n. r,. -. t, ho ctrsr.-i~.ro I ,::.: <,::z-,:... c,; :.-.<, . ? L C LA, ,...- > < A .
i
??,?
I I nc samc can be provided in atleast one longitudinal member to rcsist
Further, the first longitudinal member (1) is arc welded (A) alongwith spot
welds to the front longitudinal member (L, Fig. 2A) of the vehicle. This prevents
spot weld rupture at the point (4).
Further, the main floor and underbody structure are required to be
strengthened so as to avoid deformation at the point (3) in case of frontal
collision.
As shown in fig. 3 the first member (1) is provided with reinforcement (1')
thereunder, which covers a section of the member together with the joint (3) i.e
the reinforcement (1') partially overlaps the member (1) and extends beyond the
joint (3). Further, another reinforcement (2') is provided on the main floor in
parallel with the longitudinal member covering the joint (3) i.e. extending
beyond the joint (3).
Now, reference may be made to fig. 4 in which it can be observed that almost
no deformation takes place at the joint (A) of floor and dash lower showed by
very less plastic strains (C). Further, deformation location shifts from floor and
dash joinery to rear part (a Non critical zone) (B) with no spot weld rupture (R).
Thus, in the present invention sharp cross section changes of the longitudinal
members in transverse direction is avoided and location of bending is
reinforced by means of reinforcements of high tensile strength. Further, Arcweld
tugs are added at the location of spotweld rupture alongwith the
spotwelds in order to prevent spot weld rupture and sustain the large amount
of impact load.
Thus, the under floor structure is modified for maintaining integrity of vehicle
structure and also for reducing the intrusion of dash panel. Further, it enables
opening of door after collision and reduction in the leg injury to the occupant.
Again, it reduces front door deformation and intrusion of dash panel s as
compared to the existing under body structure.
Further, reference may be made to fig. 5 indicating load path during the head
on collision. Again, fig. 6 indicates comparison of plastic strain, from which it
can be concluded that, present invention develops negligible plastic strains and
hence no deformation.
It is to be noted that the present invention is susceptible to modifications,
adaptations and changes by those skilled in the art. Such variant
embodiments employing the concepts and features of this invention are
intended to be within the scope of the present invention, which is further set
forth under the following claims:-

. - .
1. sovci -riderbody structure of vehicle to resist vehicle cabirl deforIrlation
. <
:A?-A? A pcr:r< I ,GL <.,\iTi I collision comprising of a E:,:;r t;ctweer? ;";-:,nt and rear ?.+;bc:els
. : 1 P X ~ V I C Cw~ ith aticast two longitudinal mcmb(:rs thcr-cunder spot wcldcd
to each other wherein first longitudinal member is spot welded to front
: . , > Y > < ; ; $ :
:c,.i~ ,.L-GiAA-A xlcrrlber of vehicle in. which rcirihrcerrlcnt is provided on
,.d : >T1:?:,?
- a : L i i ~ L , , i thc floor together with a rneans k;r reinforcing conr;t:ction
: rcn:~-$ -.. .- r>-. -- -
2: Novel under body structure of vehicle as claimed in claim 1, whcrcin a
reinlc>rceiiient is provided on the first longitudinal member covering
"~\., P 1 .iillnery c;r tnc floor and dash lower.
,-. L .,
.,. .i.; .,<, \V...l .&..; ,? . .Y.\ <. I,,. *, 7 h..<..\ ,yA structure of vchiclc as c1aim::d in ::]aim 2, whcr::i~ the
rt;. r~'- ~orct:n:c;r-;~a rtially overlaps the first lc:ngi!udin2.1 ;nember.
4. Novci under body structure of vehicle as ciaimed in any of the preceding
- .
::ia~ms, whcrein znothcr reinforccmcnt is provided i:r! the main finor in
x z : . > >. > << <, f i r ! . : > > . : i.:.
i;"i'.'":',; "' A"' LA.., -.A- L. ..iiir, *\iiib"'"'.'.. .-.^ <""','"":-",' ' 7 : ",."j','. .,, ; . . .
joinery of the dash with said floor to prevent defornlation at said joint.
< NT,';ITC7'J7 n.+pr :;. . ... .. .-... I,,: body structure of vchiclc as claimcd in any of thc prcccding
c%;a. t ~~:<- Yv:v,l~i ,,iO, ,Y;Di i~ F ti:c first lcngitudinal m::mb::r is arc: weldc:! % wi.t.:-: .ti!
r. T. one iori;,: . - . s A tuc17, ' L A A L L ., i rrlerrlber of vc,.ii.ic - ic !oguc~;i:r .,i.;ir;. . spot weidirlg ..
, :
y-,- gic,v cni spot weld rupture at the joint thcrcof constituting said means.
6. Novel under body structure of vehicle as claimed any of the preceding
claims, wherein the under floor longitudinal member is provided with
beads in longitudinal direction to resist deformation with no provision of
sharp change in cross section of the first longitudinal member in
transverse direction.
7. Novel underbody structure of vehicle to resist vehicle cabin deformation
in head on collision substantially as herein described with reference to
the accompanying drawings.
Dated this 23rd day of December, 20 13 Q.
(SOMA RANI MISHRA)
OF L.S.DAVAR & CO.,
APPLICANT'S AGENT