DESCRIPTION
Title of Invention: Front Body Structure
Technical Field
[OOOl] This invention relates to a front body
structure for improving the stiffness of an automobile
body.
Background Art
[0002] As is well known, to improve the fuel
efficiency or the driving performance of automobiles or
to absorb the increase in weight accompanying safety
measures or fuller options, reduction of the weight of
15 automobiles is being sought. For this reason, for
example, high strength steel plate is being used to
reduce the thickness of the body structure and thereby
lighten the weight of the body.
[ 0 0 0 3 ] For example, when using 590 MPa class high
20 strength steel plate to lighten the body, it is
considered possible to secure the body strength while
reducing the weight by about 40% compared with
conventional steel plate. Very great results have been
anticipated.
25 [0004] On the other hand, since an automobile receives
force from bumps on the road surface while driving,
impact when riding over road shoulders etc., and various
other forces, torsional stiffness is required in addition
to body strength. However, if using high strength steel
30 plate to reduce the thickness of the body structure, even
if the body strength is secured, the torsional stiffness
generally falls.
[OOOS] That is, in high strength steel plate, the
tensile strength of the steel plate is improved by the
35 temperature history, ingredients, etc., but the Young's
modulus of iron is constant and does not change. For this
reason, if the body structure is reduced in thickness,
the polar moment of inertia of area becomes smaller. As a
result, the torsional stiffness falls.
[0006] Therefore, when using high strength steel plate
etc. to maintain the body strength while reducing the
thickness of the body so as to lighten the weight, it is
also necessary to improve the torsional stiffness.
[0007] Regarding the improvement of the torsional
stiffness of the body, as art focusing on the front body
structure, for example, art such as shown in PLTs 1 to 4
is disclosed.
[ 0 0 0 8 ] Specifically, PLT 1 discloses to form an upper
part of a strut tower at one part of a wheel apron
reinforcing member which is provided at an upper edge of
a wheel apron panel which forms the wheel housing and
connects the wheel apron reinforcing member to a subframe
which extends in the engine compartment in the vehicle
width direction.
[0009] PLT 2 discloses a front body structure provided
with reinforcing frame members with front ends which are
connected to rear parts of front side frames and with
rear ends which are connected to side panels at rear
parts of strut towers and a dash cross member which is
connected to rear parts of the reinforcing frame member
sand which extends at the bottom of a cowl part in the
width direction.
[ 0 0 10 ] PLT 3 discloses provision of a dash member at a
dash panel which extends at the rear of the engine
compartment in the width direction.
[ 0 0 11 ] PLT 4 discloses to form strut housings as
single parts and to join side members, hood ridges, a
dash panel, and a cowl top panel to the strut housings to
integrally form them together.
Citations List
Patent Literature
[0012] PLT 1: Japanese Patent Publication No. 2-
293277A
PLT 2: Japanese Patent Publication No. 2009-40127A
PLT 3: Japanese Patent Publication No. 2001-130450A
PLT 4: Japanese Patent Publication No. 2009-078575A
Summary of Invention
Technical Problem
[0013] However, to promote the reduction of weight
through the reduction of the thickness of the body
structure, it cannot be said to be sufficient to improve
the torsional stiffness of the body by just the
reinforcement disclosed in the above PLTs 1 to 4 etc. For
this reason, there is a strong demand for art for more
effective improvement of the torsional stiffness eyeing
future improvements in strength of high strength steel
plate.
[0014] Further, to secure response at the time of
changing a lane or otherwise steering a vehicle which has
the above body structure, a front body structure requires
lateral (horizontal) bending stiffness. This lateral
bending stiffness, like this torsional stiffness,
generally falls if using high strength steel plate to
reduce the thickness of the body structure. Therefore, in
the same way as torsional stiffness, there is a strong
demand for art for improvement of the lateral bending
stiffness.
[0015] The present invention was made in consideration
of this situation and has as its object the provision of
a front body structure which enables efficient
improvement of the torsional stiffness and lateral
30 bending stiffness of the body of an automobile and in
turn a front body structure which uses high strength
steel plate to reduce the thickness and thereby enable
the weight of a body to be efficiently lightened.
Solution to Problem
[0016] To solve this problem, the inventors engaged in
in-depth studies and as a result obtained the following
finding.
- By providing reinforcing members joined to the top
parts of the strut towers and to the front side members
which face the strut towers and extending between these,
it is possible to disperse the load which is input to the
strut towers.
- Using the reinforcing members, it is possible to
transmit the load in the vehicle width direction which is
applied to the top parts of the strut towers to the front
side members which face these strut towers.
[0017] The present invention was made based on the
above finding, and has as its gist the following.
(1) A front body structure in a body which has a front
compartment which is arranged at a front side of a
15 passenger compartment, characterized in comprising: a
pair of front side members which are positioned at the
inside of the front chamber and extend in a front-rear
direction of the body; a pair of strut towers which are
arranged inside the front compartment at the both sides
of a width direction of the front compartment and at the
inside of which suspensions for front wheel are
arranged; and a reinforcing member which is connected to
the top part of the strut tower and a front side member
which faces the strut tower, and which extends between
these top part and front side member.
Note that "the top parts of the strut towers" mean
parts which are positioned at the top sides when dividing
strut towers which extend from the suspension setting
parts to the front side members equally into top and
30 bottom parts.
(2) The front body structure as set forth in the above
(1) characterized in that the reinforcing member extends
along a plane perpendicular to the front-rear direction
of the body.
(3) The front body structure as set forth in the above
(1) or (2) characterized in that the reinforcing member
comprises a first reinforcing member which is connected
to a top part of a strut tower of one side in the width
direction and a front side member of the other side in
the width direction and extends between these top part
and front side member and a second reinforcing member
which is connected to a top part of a strut tower of the
other side in the width direction and a front side member
of the one side in the width direction and extends
between these top part and front side member.
(4) The front body structure as set forth in any one of
the above (1) to (3) characterized in that the
reinforcing member is comprised of a solid rod member.
(5) The front body structure as set forth in the above
(1) or (2) characterized in that the reinforcing member
is a single member which is connected to the top parts of
15 both strut towers and the two front side members.
(6) The front body structure as set forth in the above
(5) characterized in that the reinforcing member is a
panel member and in that an edge of the panel member in
the width direction is connected across the entire length
to the strut towers and front side members.
(7) The front body structure as set forth in the above
(6) characterized in that the panel member is formed with
a reinforcing bead.
Advantageous Effects of Invention
25 [0018] The load which is input from the suspensions to
the strut towers is transmitted through the side panels
or upper members etc. which form the wheel housings to
the body structure as a whole. According to all of the
front body structures of the present invention,
reinforcing members which are joined to the top parts of
the strut towers and the front side members which face
the strut towers and extend between the same are
provided. By providing such reinforcing members, the load
which is input from the suspensions to the strut towers
35 is transmitted through the existing components (side
panels and upper members) and also the reinforcing
members to the body structure as a whole. For this
reason, it is possible to disperse the load which is
input to the strut towers to transmit it to the body
structure as a whole and as a result it is possible to
effectively improve the torsional stiffness of the body
of an automobile.
[0019] Further, in all of the front body structures
according to the present invention, the reinforcing
members are joined to the top parts of the strut towers
and the front side members which face the strut towers.
For this reason, it is possible to transmit the load in
the vehicle width direction which is applied to the top
parts of the strut towers to the front side members which
face the strut towers. As a result, it is possible to
effectively improve the lateral bending stiffness at the
front of the body.
Brief Description of Drawings
[0020] FIG. 1 is a view which shows an outline of the
overall structure of a body according to a first
embodiment of the present invention.
FIG. 2 is a perspective view which shows a front body
structure according to the first embodiment.
FIG. 3 is a view of the front body structure according to
the first embodiment seen from the front.
FIG. 4 is a view which shows an outline of the overall
structure of a body according to a second embodiment of
the present invention.
FIG. 5 is a view of the front body structure, seen from
the front, according to the second embodiment.
FIG. 6 is a view of the front body structure according to
a modification of the second embodiment of the present
invention.
FIG. 7 is a view of the front body structure, seen from
the front, according to the second embodiment of the
35 present invention.
FIGS. 8 give schematic views which show one example of a
method of measurement of the torsional stiffness of a
body, wherein (A) shows a position of application of a
load in a longitudinal direction of the body structure,
while (B) is a view seen along a line X-X in (A) and
shows an outline of generation of a torque in a width
direction of the body.
FIG. 9 is a view which shows displacement and the
torsional angle of a body before and after application of
a torsional torque as seen from line X-X of FIG. 8(A).
FIG. 10 is a schematic view which shows one example of a
10 method of measurement and calculation of a lateral
bending stiffness of the body.
FIG. 11 is a view which shows displacement of the body
before and after application of the load in the width
direction as seen from the line Y-Y of FIG. 10.
Description of Embodiments
[0021] Below, referring to FIG. 1 to FIG. 3, a first
embodiment of the present invention will be explained.
FIG. 1 is a view which shows a body 1 which has a front
20 body structure 10 according to a first embodiment of the
present invention. The body 1 is provided with a
passenger compartment 2 which forms a space which a
driver and passengers ride in and a front compartment 3
which is arranged at the front side of the passenger
25 compartment 2 (left side in FIG. 1). In the present
embodiment, inside the front compartment 3, an engine or
motor or other power unit for driving the wheels is
mounted. Further, in the present embodiment, the main
material of the body 1 is high strength steel.
30 100221 The front body structure 10 according to the
present embodiment is provided with a pair of front side
members 11 which are positioned at the inside of the
front compartment 3 (in particular, in the present
embodiment, the bottom of the inside of the front chamber
35 3) and extend in a front-rear direction of the body 1 and
a pair of upper members 12 which extend at the top of the
two ends of the front compartment 3 in the width
direction in the front-rear direction of the body 1. The
front body structure 10 is further provided with a dash
panel 13 which extends in the width direction of the body
1 and separates the passenger compartment 2 and the front
compartment 3 and a pair of side panels 14 which extend
from the upper members 12 to the bottom.
100231 The side panels 14 are provided with front
wheel houses 15 and strut towers 16. The front wheel
houses 15 bulge inward in the width direction of the body
1 and are formed so as to be joined with the front side
members 11 at the bottom. The front wheel houses 15 are
structured opening outward. At the insides, front wheels
(not shown) are arranged.
[0024] Further, the strut towers 16 are formed by the
front wheel houses 15 and the side panels 17 at the top
thereof bulging out to the inside of the body 1 in the
width direction. Changing the way of viewing this, the
strut towers 16 can be said to be provided to stick out
to the top from ceiling parts of the front wheel houses
15. In particular, in the present embodiment, the heights
of the top parts of the strut towers 16 are
substantially the same as the heights of the upper
members 12. Whatever the case, the pair of strut towers
16 are arranged inside of the front compartment 3 at the
two sides of the front compartment 3 in the width
direction. Further, at the insides of the strut towers
16, suspensions for front wheels (not shown) are
arranged. At the suspension setting parts 17 of the strut
towers 16, top ends of the suspensions for front wheels
are fastened.
[0025] In addition, in the present embodiment,
reinforcing members 20 which are joined to the top parts
of the strut towers 16 and the front side members 11
which face the strut towers 16 and extend between the
same are provided. Here, "the top parts of strut towers
16" mean parts which are positioned at the top sides when
dividing strut towers which extend from the suspension
setting parts 17 to the front side members 11 equally
into top and bottom parts.
[0026] The reinforcing members 20 will be explained
more specifically. Here, as explained above, the front
side members 11 and strut towers 16 are arranged at the
two sides of the vehicle in the width direction. The ones
which are arranged at one side in the width direction (in
FIG. 3, left side) are indicated as 11L and 16L, while
the ones which are arranged at the other side in the
width direction (opposite side in width direction from
above one side in width direction, in FIG. 3, the right
side) are indicated as 11R and 16R.
[0027] The reinforcing members 20 are provided with a
first reinforcing member 21 which is connected to a top
part of a strut tower 16L of one side in the width
direction and a front side member 11R of the other side
in the width direction and extends between the same and a
second reinforcing member 22 which is connected to a top
part of a strut tower 16R of the other side in the width
direction and a front side member 11L of the one side in
the width direction. In the present embodiment, the first
reinforcing member 21 and the second reinforcing member
22 both extend along planes perpendicular to the frontrear
direction of the body (vertical planes).
[0028] The first reinforcing member 21 and the second
reinforcing member 22 are formed by for example
substantially cylindrically shaped steel pipes. First
ends are joined to the top parts of the strut towers 16,
while the other ends are joined to the front side members
11 by welding.
[0029] Here, when viewed from the front of the body 1,
the first reinforcing member 21 and the second
reinforcing member 22 are arranged crossing each other.
The intersecting parts of the first reinforcing member 21
and the second reinforcing member 22 are not constrained
by each other.
[0030] According to the front body structure 10 of the
present embodiment which is configured in this way, since
the above-mentioned such reinforcing members 20 are
provided, the load which is input from the strut towers
16 can be dispersed to the front side members 11 by the
first reinforcing member 21 and second reinforcing member
22.
[0031] That is, the load which is input from the strut
tower 16L of one side in the width direction is
transmitted to not only the upper member 12 and the front
side member 11L at one side in the width direction, but
also through the first reinforcing member 21 to the front
side member 11R of the other side in the width direction.
Due to this, deformation of the strut tower 16L due to
the load is suppressed. In the same way, the load which
is input to the strut tower 16R of the other side in the
width direction is transmitted not only to the upper
member 12 and front side member 11R at the other side in
the width direction, but also through the second
reinforcing member 22 to the front side member 11L of the
one side in the width direction. Due to this, deformation
of the strut tower 16R due to the load is suppressed. Due
to this, it is possible to improve the torsional
stiffness of the body 1 as a whole.
[0032] Further, the suspension setting parts 17 of the
strut towers 16 are sometimes subjected to load in the
vehicle width direction along with turning of the vehicle
etc. According to the front body structure 10 of the
present embodiment, the load in the vehicle width
direction which is input from the strut tower 16L of one
side in the width direction is transmitted to not only to
the upper member 12 and the front side member 11L of the
one side in the width direction, but also through the
first reinforcing member 21 to the front side member 11R
at the other side in the width direction. Similarly, the
load in the vehicle width direction which is input from
the strut tower 16R of the other side in the width
direction is transmitted to not only to the upper member
12 and the front side member 11R of the other side in the
width direction, but also through the second reinforcing
member 22 to the front side member 11L at the one side in
the width direction. Due to this, it is possible to
5 improve the lateral bending stiffness of the front of the
body.
[0033] Furthermore, since the first reinforcing member
21 and the second reinforcing member 22 are arranged
along planes perpendicular to the front-rear direction of
10 the body 1 (vertical planes), it is possible to
efficiently transmit the load which is input from the
strut towers 16 to the front side members 11. Due to
this, it is possible to suppress the torsional
deformation of the front body structure 10 to a higher
15 extent and possible to improve the torsional stiffness of
the body 1 as a whole.
[0034] Next, referring to FIG. 4 and FIG. 5, a second
embodiment of the present invention will be explained.
FIG. 4 is a view which shows a body 51 which has a front
20 body structure 60 according to a second embodiment of the
present invention. Note that members the same as the
first embodiment are assigned the same reference
notations and detailed descriptions are omitted.
[0035] In the front body structure 60 according to the
25 second embodiment, as the reinforcing members, a single
panel member 70 which is joined to the pair of front side
members 11 and the pair of strut towers 16 is arranged.
In particular, in the present embodiment, the edge of the
panel member 70 in the width direction is joined across
30 its entire length to the strut towers 16 and front side
members 11. Therefore, in the present embodiment, the
panel member 70 can be said to be joined to both the top
parts and the bottom parts of the strut towers 16.
[0036] In more detail, the edge 70L of one side of the
35 panel member 70 in the width direction is joined to the
top and bottom of the strut tower 16L of one side in the
width direction and to the front side member 11L.
Further, the edge 70R of the other side of the panel
member 70 in the width direction is joined to the top and
bottom of the strut tower 16R of the other side in the
width direction and to the front side member 11R. In the
present embodiment, the panel member 70 is arranged along
the plane perpendicular to the front-rear direction of
the body 51 (vertical plane).
[0037] The panel member 70 is formed from steel plate.
It is joined at its entire length in the width direction
edge by laser welding to the strut tower 16 and front
side member 11. Further, the panel member 70 is formed
with a reinforcing bead 75 for improving the strength of
the panel member 70 itself. In the present embodiment, as
shown in FIG. 5, a plurality of reinforcing beads 75 are
formed extending in the width direction. Further, in the
present embodiment, the reinforcing beads 75 are formed
by a press and are formed in rectangular cross-sectional
shapes with single open sides.
COO381 According to the front body structure 60 of the
20 present embodiment configured in this way, since the
above-mentioned panel member 70 is provided as the
reinforcing members, the load which is input from the
strut towers 16 can be dispersed by the panel member 70
to the front side members 11. Accordingly, it is possible
25 to suppress the deformation due the load which is input
from the strut towers 16 by the panel member 70. As a
result, it is possible to improve the torsional stiffness
of the body 51 as a whole. Further, in the same way as
the first embodiment, it is possible to improve the
30 lateral bending stiffness at the front of the body as
well.
[0039] Furthermore, in the present embodiment, since
the panel member 70 is arranged along a plane
perpendicular to the front-rear direction of the body 51
35 (vertical plane), the load which is input from the strut
towers 16 can be efficiently transmitted to the front
side members 11. Due to this, the torsional stiffness of
the body 51 as a whole can be further improved.
[ 0 0 4 0 ] Further, since the panel member 70 is formed
with reinforcing beads 75, the panel member 70 itself can
be improved in strength and deformation can be
5 suppressed. Therefore, torsional deformation of the front
body structure 60 can be suppressed by a higher extent.
[0041] Furthermore, in the present embodiment, the
panel member 70 is joined at the entire length of its
edge in the width direction by laser welding to the strut
10 towers 16 and front side members 11. For this reason, the
joined strength of the panel member 70 to the strut
towers 16 and front side members 11 is improved and
torsional deformation of the front body structure 60 can
be suppressed.
15 [0042] Further, according to the present embodiment,
at the time of impact, the parts which are housed in the
front chamber 53 can be kept from entering the passenger
compartment 52 by the panel member 70.
[ 0 0 4 3 ] Embodiments of the present invention were
20 explained, but the present invention is not limited to
the above embodiment. Various changes can be made within
a scope not deviating from the gist of the invention.
[ 0 0 4 4 ] For example, in the above embodiments, the case
where the main material of the body was high strength
25 steel was explained, but all or part of the body may also
be formed from aluminum, FRP, or another material which
can generally be used for a body. Further, high strength
steel was used for the reinforcing members, but aluminum,
FRP, and other materials may also be used. In addition,
30 the reinforcing beads do not necessarily have to be given
cross-sections of rectangular shapes open at one side.
They may also be made trapezoidal shapes open at one side
or semicircular shapes, semi-oval shapes, and various
other shapes.
35 COO451 Further, the first embodiment was explained
assuming the first reinforcing member 21 and the second
reinforcing member 22 were formed by approximately
cylindrically shaped steel pipes, but the invention is
not limited to this. For example, the first reinforcing
member 21 and the second reinforcing member 22 may be rod
members of cross-sectional shapes different from
5 cylindrical shapes such as rectangular shapes. Further,
they may also be formed with thicker center sides or
formed flaring outward toward the ends.
[0046] Furthermore, in the first embodiment, the first
reinforcing member 21 and the second reinforcing member
10 22 are joined by welding to the top parts of the strut
towers 16 and the front side members 11, but the joining
method is not limited to this. Therefore, as the joining
method, it is also possible to employ a system using
bolts or rivets etc. for fastening or other methods.
15 100471 Further, in the first embodiment, the first
reinforcing member 21 and the second reinforcing member
22 may also be formed by solid rod members (wires or
steel rods etc.) In this case, the space occupied by the
first reinforcing member 21 and the second reinforcing
20 member 22 can be kept small. As a result, it is possible
effectively utilize the space while improving the
torsional stiffness. Here, for example, when a load
directed upward is input to one side in the width
direction, a tensile force acts on the first reinforcing
25 member 21 which connects the strut tower 16 of one side
in the width direction and the front side member 11 of
the other side in the width direction, but this tensile
force can be received by the first reinforcing member 21
comprised of steel wire and torsional deformation of the
30 body 1 is suppressed.
[ 0 0 4 8 ] Furthermore, in the first embodiment, as
explained above, the first reinforcing member 21 and the
second reinforcing member 22 both extend along planes
perpendicular to the front-rear direction of the body.
35 However, they do not necessarily have to extend along the
planes. They may also extend along planes inclined with
respect to these planes. Further, the planes along which
the first reinforcing member 21 and the second
reinforcing member 22 extend do not necessarily have to
be parallel. The members may also be formed so as to
extend on planes which are not parallel with each other.
5 However, these first reinforcing member 21 and second
reinforcing member 22 are preferably arranged
substantially symmetrically about a plane extending in
the front-rear direction of the body at the center of the
body in the width direction.
10 [0049] In addition, in the first embodiment, the
intersecting parts of the first reinforcing member 21 and
the second reinforcing member 22 are formed so as to not
be constrained by each other, but these first reinforcing
member 21 and second reinforcing member 22 may also be
15 formed so as to be joined and fastened to each other. In
this case, the first reinforcing member 21 and the second
reinforcing member 22 may be arranged on the same plane.
Due to this, the body can be further improved in
torsional stiffness.
20 [OOSO] Further, in the second embodiment, the
explanation was given assuming the panel member 70 was
provided with reinforcing beads 75 extending in the width
direction, but the shape of the reinforcing beads 75 is
not limited to the shape of FIGS. 4 and 5. Therefore,
25 instead of the panel method 70 which is shown in FIGS. 4
and 5, for example, as shown in FIG. 6, it is also
possible to use a panel member 80 which is provided with
a bead 85 which extends between the top part of the strut
tower 16L of one side in the width direction and the
30 front side member 11R at the other side in the width
direction and a bead 86 which extends between the top
part of the strut tower 16R of the other side in the
width direction and the front side member 11L at one side
in the width direction. Alternatively, as shown in FIG.
35 7, a panel member 90 which is provided with a plurality
of X-shaped beads 95 in the vehicle width direction may
also be used.
[0051] Furthermore, in the second embodiment, the
explanation was given assuming the panel member 70 was
laser welded along the entire length of the edge in the
width direction, but the method of joining the panel
5 member 70 is not limited to this. Therefore, as the
joining method, the method of using spot welding, the
method of using bolts, rivets, etc., and other methods
may also be employed.
[0052] In addition, in the second embodiment, as
10 explained above, the panel member 70 extends along a
plane perpendicular to the front-rear direction of the
body. However, it does not necessarily have to extend
along this plane. It may also extend along a plane
inclined with respect to this plane.
15 [0053] Further, the present embodiments were explained
assuming the front compartment mounted a motor or engine
or other power unit, but the invention is not limited to
this. It may also be used as a luggage compartment etc.
[0054] Further, the front body structure according to
20 the present invention can of course be applied to not
only an automobile which mounts an internal combustion
engine, but also a hybrid vehicle or an electric vehicle
in which motors are provided at the wheels etc. Note
that, in the above-mentioned electric vehicle etc., since
25 there is no need to mount a large sized engine in the
front chamber, the first reinforcing member and the
second reinforcing member can be reliably arranged.
[0055] Further, the shape of the body as a whole is
not limited to the one disclosed in FIG. 1 and FIG. 4. It
30 may also be made a station wagon type, minivan type, SUV
type, or other shape.
Examples
[0056] Here, to confirm the effect on the present
35 embodiment, for example, the technique which is shown in
FIG. 8 and FIG. 9 was used to calculate the torsional
stiffness, while the technique which is shown in FIG. 10
was used to calculate the lateral bending stiffness.
COO571 Below, first, referring to FIG. 8 and FIG. 9,
the method of measurement and calculation of the
torsional stiffness will be explained. FIG. 8 is a
5 conceptual view which shows the method of measurement and
calculation of the torsional stiffness of the body-inwhite
(body) 100, while FIG. 9 is a view for explaining
the torsional stiffness based on the torsion of the front
axle position lOOF (position in front-rear direction of
10 body at which front shaft is arranged) based on the rear
axle position lOOR (position in front-rear direction of
body at which rear shaft is arranged).
[0058] To measure the torsional stiffness, for
example, as shown in FIG. 8(A), the body-in-white 100 is
15 fastened at the rear axle position lOOR and the average
specific torsional stiffness GJ which is obtained by
application of the torsional torque at the front axle
position lOOF is used for evaluation (G: modulus of
rigidity, J: polar moment of inertia of area).
20 COO591 Specifically, at the rear axle position 100R,
the body-in-white 100 is fastened (for example, the
suspension setting parts RL and RR of the rear strut
towers are fastened) and the top ends of dummy bars 101
are attached to the suspension setting parts FL and FR of
25 the front strut towers. In this state, a seesaw table 102
to which the bottom ends of the dummy bars 101 are
attached is turned about the axis 0. Due to this, a
torsional torque T is applied to the suspension setting
parts FL and FR of the front strut towers (see FIG. 8 (B)) .
30 [0060] FIG. 9 is a view which shows the body crosssection
at the front axle position 100F seen from the
line X-X of FIG. 8(A). The specific torsional stiffness
GJ is calculated based on the left and right
displacements 6L and 6R of the body which occur at the
35 front axle position 100F at the time of application of
the above torsional torque T. Note that, in FIG. 9, lOOC
which is shown by the two-dot chain line and lOOD which
is shown by the solid line show the body (outside shape)
before and after application of the torsional torque T.
[0061] Here, since the torsion angle B(rad) due to the
torsional torque T is small, it can be approximated as
5 B%tanB=( (6L+6R/)B ) ; (B is body width dimension relating to
application of torsional torque T at front axle position
100F).
Specific Torsional stiffness G~=(~/(B/wheelbaslee ngth L))
= (T .B .wheelbase length L) / (6,+6,)
10 (For example, see "Strength of Automobiles", Sankaido,
October 30, 1990, second edition)
[0062] Next, referring to FIG. 10 and FIG. 11, the
method of measurement and calculation of the lateral
bending stiffness will be explained. FIG. 10 is a
15 conceptual view which shows the method of measurement of
the lateral bending stiffness of the body-in-white 100,
while FIG. 11 is a view for explaining the lateral
bending stiffness based on displacement in the width
direction at the front axle position 100F. As shown in
20 FIG. 10, when measuring the lateral bending stiffness,
instead of the rear axle position 100R, the body is
fastened at the side sill intermediate parts 105.
[0063] Further, in the same way as FIG. 8 (B), the top
ends of dummy bars 101 are attached to the suspension
25 setting parts FL and FR of the front strut towers. In this
state, a seesaw table 102 to which the bottom ends of the
dummy bars 101 and 101 are attached is moveed in the
vehicle width direction and due to this, a width
direction load L is applied to the suspension setting
30 parts FL and FR of the front strut towers.
[0064] FIG. 11 is a view which shows the body crosssection
at the front axle position 100F seen from the
line Y-Y of FIG. 10. The value of the lateral bending
stiffness is calculated based on the displacement 6w in
35 the width direction of the body occurring at the front
axle position lOOF when applying the load L in the width
direction. Note that, in FIG. 11, 100E which is shown by
the two-dot chain line and lOOF which is shown by the
solid line show the body (outside shape) before and after
application of the width direction load L. In this case,
5 the lateral bending stiffness is expressed as follows:
Lateral bending stiffness = Input load L/load point
displacement 6,
[0065] In this example, as the conventional example, a
model where the first reinforcing member and second
10 reinforcing member and the panel member were not arranged
was used. As an invention example, as shown in the first
embodiment, a model where a first reinforcing member and
second reinforcing member are arranged was used. Note
that the first reinforcing member and second reinforcing
15 member were steel pipes having outside diameter of 20 mrn
and thickness of 2 rnrn.
[0066] The above measurement and calculation method
was used to calculate the torsional stiffness and the
lateral bending stiffness. As a result, in the invention
20 example, it was confirmed that the torsional stiffness is
improved 5.49% and the lateral bending stiffness is
improved 26% compared with the conventional example.
Industrial Applicability
25 [0067] By improving the torsional stiffness and
lateral bending stiffness of the body structure of an
automobile, it is possible to improve the stability while
the automobile is being driven, so there is great
industrial applicability.
30
Reference Signs List
[0068] 1, 51 body
2, 52 passenger compartment
3, 53 front compartment
35 10, 60 front body structure
11 front side member
16 strut tower
20 reinforcing member
21 first reinforcing member
22 second reinforcing member
70 panel member
75 reinforcing bead

CLAIMS
Claim 1. A front body structure in a body which has a
front compartment which is arranged at a front side of a
passenger compartment, characterized in comprising:
a pair of front side members which are
positioned at the inside of said front chamber and extend
in a front-rear direction of said body;
a pair of strut towers which are arranged
inside said front compartment at the both sides of a
width direction of said front compartment and at the
inside of which suspensions for front wheel are arranged;
and
a reinforcing member which is connected to
the top part of said strut tower and a front side member
which faces said strut tower, and which extends between
these top part and front side member.
Claim 2. The front body structure as set forth in claim
1 characterized in that said reinforcing member extends
along a plane perpendicular to the front-rear direction
of the body.
Claim 3. The front body structure as set forth in claim
1 or 2 characterized in that said reinforcing member
comprises a first reinforcing member which is connected
to a top part of a strut tower of one side in the width
direction and a front side member of the other side in
the width direction and extends between these top part
and front side member and a second reinforcing member
which is connected to a top part of a strut tower of the
other side in the width direction and a front side member
of the one side in the width direction and extends
between these top part and front side member.
Claim 4. The front body structure as set forth in any
one of claims 1 to 3 characterized in that said
reinforcing member is comprised of a solid rod member.
Claim 5. The front body structure as set forth in claim
1 or 2 characterized in that said reinforcing member is a
single member which is connected to the top parts of both
strut towers and the two front side members.
Claim 6. The front body structure as set forth in claim
5 characterized in that said reinforcing member is a
panel member and in that an edge of the panel member in
5 the width direction is connected across the entire length
to the strut towers and front side members.
Claim 7. The front body structure as set forth in claim
6 characterized in that said panel member is formed with
a reinforcing bead.